The phenology of figs （Ficus spp. Moraceae） is being monitored in the dry forests of Mudumalai, southern India and individuals belonging to the genus are marked with unique tag numbers and their vegetative and repro...The phenology of figs （Ficus spp. Moraceae） is being monitored in the dry forests of Mudumalai, southern India and individuals belonging to the genus are marked with unique tag numbers and their vegetative and reproductive phenologies have been monitored since August 2000 on a monthly basis. The influence of abiotic factors on fig phenology and the differences between fig and non- fig phenologies are being examined. The seasonality of different phenophases of fig phenology is also being examined. The maximum intensity of leaf flush occurred in drier months. Fig and non-fig species showed significant differences with expansion and senescence phenophases of leafing. Flowering also occurred in drier months. There were significant differences between fig and non-fig species with reproductive phenophases. As with non-fig species, leafing was influenced by maximum temperatures. Both vegetative and reproductive phenophases were significantly seasonal.展开更多
Based on 120 stem discs collected during3 months of fieldwork along a 12 km route,the history of fires in the Wari Maro Forest（09 1000 N–02 1000E） over the past century in savanna woodland and dry forest was recons...Based on 120 stem discs collected during3 months of fieldwork along a 12 km route,the history of fires in the Wari Maro Forest（09 1000 N–02 1000E） over the past century in savanna woodland and dry forest was reconstituted.Three major ecological areas are characterized：one highly burnt zone located between two relative less burnt areas.By analyzing tree rings,246 fire scars were identified.The scars were caused by 51 fire years,occurring at a mean interval of 2.23 years.From 1890 to1965,only 6 years with fires were recorded from sampled trees.Since 1966,no year has passed without fire.The fire frequency point scale reached 14 years.This was the case of Burkea africana,which has been identified as a species tolerant to fire and could be planted to create a natural firewall.In contrast,Anogeissus leiocarpa is highly sensitive to fire,and in a dry forest ecosystem that burns seasonally,it requires a special conservation plan.Two new concepts are described：the rebarking of trees after fire and Mean Kilometer Fire Interval.The first concept was tested with Daniellia oliveri（Rolfe） Hutch ＆ Dalz trees,and the second concept was used to evaluate spatial fire distribution.We demonstrate that savanna woodland and dry forest were subject to a degradation process caused by destructive fires related to vegetation cover clearance and illegal logging.展开更多
We carried out this research at Abu-Gaddaf Natural Forest Reserve (ANFR) which is located east of Blue Nile River, in Blue Nile State, Sudan. It aims at exploring tree composition assessing their diversity indices, an...We carried out this research at Abu-Gaddaf Natural Forest Reserve (ANFR) which is located east of Blue Nile River, in Blue Nile State, Sudan. It aims at exploring tree composition assessing their diversity indices, and ecological importance values. For survey of types and estimation of density of tree species in the forest, we randomly distributed 97 circular sample plots (0.1 hectare (ha)). In each sample plot we identified all trees to the species level, recorded their frequencies and computed species diversity and importance value indices (IVI). A total of 13 tree species, which belong to 12 genera and nine families, were identified in the tree layer of the forest. Mean tree density in ANFR was 116 trees/ha, composed mainly of Boswellia papyrifera (Del.) Hochst. (48), followed by Combretum hartmannianu (19) and Lannea fruticosa (18). Fabaceae was the most common family followed by Combretaceae and Malvaceae. B. papyrifera Delile Hochst was the most abundant while Acacia seyal was the least abundant species. Species richness (R = 1.71), evenness (E = 0.69), dominance (0.24) indices and Simpson’s Index of Diversity (D' = 0.76) suggest a moderate diversity, moderate numbers of individuals in each species and a moderate community stability. The research provides empirical results on diversity and ecological importance value of species, signifies the urging need to safeguard threatened species and to prioritize them for conservation, as well as the need to promote management of abundant species to provide multiple forest ecosystem services.展开更多
Background:In tropical dry forests,variation in understory light availability due to season and canopy tree density could be a governing factor in establishment and growth of tree seedlings.Species with varying life h...Background:In tropical dry forests,variation in understory light availability due to season and canopy tree density could be a governing factor in establishment and growth of tree seedlings.Species with varying life history traits are expected to respond differentially to such heterogeneity.We investigated the response of seedlings of four tree species in a tropical day forest in relation to spatiotemporal variability of light.We attempt to explore the role of leaf attributes in explaining intra-and inter-specific variations in relative growth rate.Four study sites,each with three contrasting canopy conditions,were selected along a soil moisture gradient.Seedlings of four tree species(viz.,Acacia catechu,Bridelia retusa,Lagerstroemia parviflora,and Shorea robusta),varying in life history traits,were monitored for seasonal variations in growth traits across canopy condition and sites for 2 years.Results:We observed a larger variation in leaf attributes for pioneer species.A.catechu showed highest mean values for leaf dry matter content,leaf nitrogen concentration,leaf phosphorus concentration,net stomatal conductance,net photosynthetic rate,and relative growth rate in high light conditions.S.robusta and B.retusa demonstrated highest mean values for all the leaf attributes(except leaf dry matter content)in low light conditions.However,intermediate values for leaf attributes were observed in L.parviflora which preferred moderate light conditions.Conclusions:Seasonal variations in light availability at the forest floor appear to play an important role in the establishment and growth of tree seedlings in seasonal dry forests.Leaf attributes can be used to explain intra-and inter-specific variation in response to light availability.Leaf attributes in combinations can be used to predict relative growth rate of tree species in tropical dry environment,which apart from soil moisture is also determined by light availability due to seasonal changes and canopy tree density.展开更多
Aims Increasing anthropogenic nitrogen(N)deposition has been claimed to induce changes in species composition and community dynamics.A greenhouse experiment was conducted to examine the effect of increased N availabil...Aims Increasing anthropogenic nitrogen(N)deposition has been claimed to induce changes in species composition and community dynamics.A greenhouse experiment was conducted to examine the effect of increased N availability on growth and functional attributes of seedlings of five tree species with different life history characteristics under varying irradiances.The following questions have been addressed:(i)how do the pioneer and non-pioneer species respond in absolute growth and relative growth rate(RGR)to the interaction of light and nitrogen?(ii)how does the interaction between irradiance and nitrogen availability modulate growth attributes(i.e.functional attributes)?(iii)is there any variation in growth responses between leguminous and non-leguminous species along the light and nitrogen gradients?Methods Seedlings of five tree species(Acacia catechu,Bridelia retusa,Dalbergia sissoo,Lagerstroemia parviflora and Terminalia arjuna)were subjected to twelve combinations of irradiance and N levels.Various growth traits,including height(HT),basal area(BA),whole plant dry biomass(MD),leaf mass per unit area(LMA),leaf area ratio(LAR),net assimilation rate(NAR),RGR,biomass fractions,root-toshoot ratio(R:S)and leaf nitrogen content,were studied to analyse intra-and inter-specific responses to interacting light and N gradients.Important Findings Significant interactions for irradiance and N availability for majority of growth attributes indicates that growth and biomass allocation of seedlings were more responsive to N availability under high irradiance.However,species responded differentially to N addition and they did not follow successional status.Slow growers(B.retusa,a shade-tolerant species and L.parviflora,a light demander)exhibited greater response to N enrichment than the fast growers(A.catechu,D.sissoo and T.arjuna).However,N-mediated increment in growth traits was greater in non-legumes(B.retusa,L.parviflora and T.arjuna)compared with that of legumes(A.catechu and D.sissoo).Allocation of biomass to root was strongly suppressed at the highest N supply across species;however,at high irradiance and high N availability,a greater suppression in R:S ratio was observed for B.retusa.NAR was a stronger determinant of RGR relative to LAR,suggesting its prominent role in increased RGR along increasing irradiances.Overall,a higher growth response of slow-growing species to elevated N levels,particularly the non-pioneers(B.retusa and L.parviflora)suggests that future N deposition may lead to perturbations in competition hierarchies and species composition,ultimately affecting community dynamics in nutrient-poor tropical dry forests.展开更多
This review attempts to synthesize the available literature on tropical dry forests and their dynamics in the context of climate change and thereby identifies possible gaps and priority areas for further research and ...This review attempts to synthesize the available literature on tropical dry forests and their dynamics in the context of climate change and thereby identifies possible gaps and priority areas for further research and management endeavors.Tropical dry forests(TDFs)occur in dryland environments,which are characterized by prolonged periods of dry months.They experience distinct seasonality and high inter-annual variability in climatic variables,particularly rainfall.Despite the enormous ecological and livelihood importance of TDFs,these forests are highly threatened by global changes.So far,they have received far less attention from research and development interventions as compared to the humid tropical forests.Their significance is still overlooked in many countries’national policies.Current modeling frameworks show that drought,precipitation,and temperature are highlighted as strong drivers of tree growth and/or mortality in these forests.Well-valued and sustainably managed TDFs have the potential to contribute to climate change adaptation and mitigation,buffer against erosion and desertification,and contribute to economic development,food security,and poverty alleviation.TDFs suffer notable disregard from research and development strategies.Thus,greater awareness and appropriate policies and investments are needed at various levels to counteract the increasing vulnerability of people,forest ecosystems,and species living in these fragile ecosystems.Further research is also needed to generate knowledge on the status and significances of TDFs and their responses in the face of the changing climate so as to bring their sustainable management to the attention of policymakers and managers.展开更多
Aims Soil moisture content(SMC)influences establishment,survival and development of plant species and is considered as the most important limiting factor in tropical dry forest(TDF).In this study we attempt to establi...Aims Soil moisture content(SMC)influences establishment,survival and development of plant species and is considered as the most important limiting factor in tropical dry forest(TDF).In this study we attempt to establish the relationship between leaf attributes and of tree saplings in TDF and address the following questions:(i)how are the functional attributes of dominant tree saplings of TDF affected by seasonal changes in SMC at different habitats?,(ii)what is the relationship of functional attributes with each other?,(iii)how are the functional attributes and their plasticity affected by habitat con-ditions?and(iv)can the functional attributes in single or in com-bination predict the growth rate of tree saplings of TDF?The study was conducted on four sites(Hathinala,Gaighat,Harnakachar and Ranitali,listed in order of decreasing SMC)within the tropical dry deciduous forest in northern India.Methods We analysed eight leaf attributes,specific leaf area(SLA);leaf dry matter content(LDMC);leaf nitrogen concentration(leaf N);leaf phosphorus concentration(leaf P);chlorophyll concentration(Chl);mass-based photosynthetic rate(Amass);mass-based stomatal con-ductance(Gsmass);intrinsic water use efficiency(WUEi)and three growth attributes,relative diameter increment(RDI);relative height increment(RHI);relative growth rate(RGR)of the 10 dominant tree saplings(viz.,Acacia catechu,Anogeissus latifolia,Boswellia serrata,Buchanania lanzan,Diospyros melanoxylon,Hardwickia binata,Lagerstroemia parviflora,Lannea coromandelica,Shorea robusta and Terminalia tomentosa)of a TDF and observed the effects of site,season and species for a period of 2 years.Saplings were selected in gradients of deciduousness.Step-wise multiple regression was performed to predict RDI,RHI and RGR from mean values of SMC and leaf attributes.Important Findings All the 11 attributes were interrelated and differed significantly among the 10 saplings.Species response varied across sites and seasons.Across the SMC gradient,the attributes showed variable plasticity that differed across species.Among the 10 saplings,the highly deciduous Boswellia serrata showed the maximum plasticity in seven functional attributes.According to the step-wise multiple regressions,65%variability in RDI and 67%variability in RGR were due to Gsmass,and for RHI,61%variability was due to Amass.SMC and the other attributes,viz.,SLA,Chl,WUEi and LDMC in combination could contribute only for~2-6%of the variability in RDI,RHI and RGR,which indicates that other traits/factors,not accounted in this study are also important in modulating the growth of tree saplings in TDFs.In conclusion,growth of the tree saplings in the tropical dry environment is determined by soil moisture,whereas the response of saplings of different tree species is modulated by alterations in key functional attributes such as SLA,Chl,WUEi and LDMC.展开更多
A study was conducted to examine the natural regeneration of three dry forest species, Lysiloma divaricatum （Jacq.）, Tabebuia ochracea （Cham.） and Lonchocarpus minimiflorus （Donn. Sin.） over a three-year period ...A study was conducted to examine the natural regeneration of three dry forest species, Lysiloma divaricatum （Jacq.）, Tabebuia ochracea （Cham.） and Lonchocarpus minimiflorus （Donn. Sin.） over a three-year period and to analyze heterogeneity of regeneration in relationship to topographic slope and incidence of light in Chacocente Wildlife Reserve in Nicaragua. Permanent sample plots were established in 2001, and all individuals with height as low as 10 cm and diameter as large as 10 cm were recorded for three consecutive years from 2001 to 2003. The results show that the density of naturally regenerated individuals varied significantly among species, as well as over time. L. minimiflorus and T. ochracea had higher densities compared with L. divaricatum, and the net change in population density was slightly positive for T. ochracea only. Regeneration was more abundant in the gentle and steep slopes under partial exposure of the crown to sunlight, thus resulting in aggregated pattern of distribution, especially for L. minimiflorus and T. ochracea. We concluded that natural regeneration alone is not sufficient to maintain the desired number of stocks of these species, and an immediate restoration measure should be taken to assist the natural regeneration process.展开更多
Aims Seasonally tropical dry forests of the Yucatan Peninsula are typically found in sites with nutrient-poor soils because of the recent geologi-cal origin of the region.The landscape is dominated by extensive karsti...Aims Seasonally tropical dry forests of the Yucatan Peninsula are typically found in sites with nutrient-poor soils because of the recent geologi-cal origin of the region.The landscape is dominated by extensive karstic plates that shape environments where vegetation regenera-tion through seed germination may be limited by the availability of suitable microsites.In this study,we documented the survival and growth of seedlings from three dominant tree species(Bursera simaruba,Piscidia piscipula and Lysiloma latisiliquum)in seasonally tropical dry forests in Yucatan.Specifically,we evaluated the effect of nutrient addition(N and P,separately and in combination)on seedling survival and growth across three sites with differing levels of precipitation.Methods We conducted a nutrient addition experiment,whereby we estab-lished 12 plots of dimensions 10×10 m(100 m^(2))at each site,from which three plots were randomly selected to receive one of four treatments:N addition,P addition,N and P addition and no nutri-ent addition(controls).Prior to treatment application,in each plot,we planted 10 seedlings of each species in October 2010 and sub-sequently conducted surveys of plant growth and survival every 20 days from November 2010 to April 2011.Important Findings Overall,nutrient addition increased seedling survival and the mag-nitude of this effect was similar among sites.We did not observe an additive effect of the N+P treatment on survival.Similarly,we observed a positive effect of nutrient addition on seedling growth,but this effect was contingent upon site;regarding survival,the effects of N and P on seedling growth were not additive.These results suggest that seedling recruitment and growth in the three dominant species of trees in Yucatan are limited by nutrient avail-ability but that the magnitude of this effect,particularly on seedling growth,is specific for species and site.展开更多
Introduction:A fundamental challenge to the integrity of tropical dry forest ecosystems is the invasion of nonnative grass species.These grasses compete for resources and fuel anthropogenic wildfires.In 2012,a bulldo...Introduction:A fundamental challenge to the integrity of tropical dry forest ecosystems is the invasion of nonnative grass species.These grasses compete for resources and fuel anthropogenic wildfires.In 2012,a bulldozer from the Puerto Rico Electric Power Authority cleared a 570-m trail from a state road into a mature dry forest section of Guánica Forest to control a wildfire.We monitored colonization by a non-native invasive grass(Megathyrsus maximus),a highly invasive tree(Leucaena leucocephala),and a native grass(Uniola virgata),as well as natural regeneration,along the bulldozer trail.We determined whether bulldozing facilitated colonization by these species into the forest and the extent of spread.Results:Distance from propagule source and temporal variations strongly influenced colonization by our three focal species.Megathyrsus maximus invaded along the trail from source populations by the state road.The establishment of new colonies of M.maximus seedlings went as far as 570 m inside the forest(i.e.,at the end of the bulldozer trail),but we found most new colonies within 270 m of the road.Leucaena leucocephala exhibited a similar spreading pattern.Before disturbance,Uniola virgata was distributed widely across the forest,but the highest densities were found in areas near the latter portion(>401 m)of the bulldozer trail.Subsequently,the species formed new clumps along more than half of the trail(250 to 570 m),apparently colonizing from undisturbed patches nearby.Conclusions:Bulldozing facilitated the invasion of non-native vegetation.The projected community assemblage will be more fire-prone than before since M.maximus carries fire across the landscape better than U.virgata,emphasizing the capacity of invasive plant colonization to alter local ecological processes after only a single wildfire and bulldoze event.Our results provide a valuable baseline for short-term vegetation response to anthropogenic disturbances in tropical semi-deciduous dry forests.展开更多
Arbuscular mycorrhiza fungi(AMF) are vital in the regeneration of vegetation in disturbed ecosystems due to their numerous ecological advantages and therefore are good indicators of soil and ecosystem health at large....Arbuscular mycorrhiza fungi(AMF) are vital in the regeneration of vegetation in disturbed ecosystems due to their numerous ecological advantages and therefore are good indicators of soil and ecosystem health at large. This study was aimed at determining how the seasonal, vegetation cover density, edaphic and anthropogenic factors affect AMF root colonization(RC) and spore density(SD)in Desa’a dry Afromontane forest. AMF RC and SD in the rhizosphere of five dominant woody species, Juniperus procera, Olea europaea, Maytenus arbutifolia, Carissa spinarum and Dodonaea angustifolia growing in Desa’a forest were studied during the rainy and the dry seasons in three permanent study vegetation cover density plots(dense, medium, and poor). Each plot(160 x40 m2) has two management practices(fenced and unfenced plots) of area. A 100 g sample of rhizosphere soil from moisturefree composite soil was used to determine spore density.Spore density ranged from 50 to 4467 spores/100 g soil,and all species were colonized by AMF within a range of 4–95%. Glomus was the dominant genus in the rhizosphere of all species. Vegetation cover density strongly affected SD and RC. The SD was significantly higher(p < 0.05) in the poor vegetation cover density than in the other two and lowest in the dense cover; root colonization showed the reverse trend. Management practices significantly(p <0.05) influenced AMF SD and RC, with the fenced plots being more favoured. Seasons significantly(p < 0.05) affected RC and SD. More RC and SD were observed in the wet period than the dry period. Correlating AMF SD and RC with soil physical and chemical properties showed no significant difference(p> 0.05) except for total nitrogen. Disturbance, vegetation cover density, season and total nitrogen are significant factors that control the dynamics and management interventions to maintain the forest health of dry Afromontane forests.展开更多
The advent of modem forces and the changes in socio- economic patterns of forest dwellers have increased the pressures on the forests. In order to mitigate such pressures and also to protect the forests and wildlife t...The advent of modem forces and the changes in socio- economic patterns of forest dwellers have increased the pressures on the forests. In order to mitigate such pressures and also to protect the forests and wildlife the model of protected areas networks has shifted and en- hanced such pressures in the unprotected natural forests due to several reasons. Being a low profile category of protected status and continuous human settlements, the present study highlights the case of dry deciduous forests of Sarguja district of Chhattisgarh state of India. The major objec- tives of this study were to quantify the status of forests and wildlife and also to determine the extent of anthropogenic disturbances faced by the dry deciduous forests of central India. Transect and silent drive count methods were used for sampling wildlife and quadrat method was used for sampling vegetation. Besides, the local uses of various forest pro- duces were also studied in view of understanding the people dependency on forests. The forest vegetation, in the study area, was pre-dominated by Shorea robusta, which had Madhuca indica, Diospyrus melanoxylon and Buchnania lanzan as the major companion species. The forest had either the high girth class mature tree species or the saplings. The low vegeta- tion cover and density were due to the high anthropogenic pressures mainly in the form of heavy livestock grazing and collection of etlmo- botanically important species. The study though reveals that the area is not rich in wildlife and the forest is fragmented, the area still supports some important species, which include many rare and endangered plants and animals. The findings of this study have been discussed in view of the management and conservation of the forest and wildlife in the dry deciduous forests.展开更多
In 2013, we re-inventoried all lianas （≥1 cm diameter measured at 1.3 m from the rooting point） in four I-ha permanent plots distributed one each in four sites of inland tropical dry evergreen forest on the Coroman...In 2013, we re-inventoried all lianas （≥1 cm diameter measured at 1.3 m from the rooting point） in four I-ha permanent plots distributed one each in four sites of inland tropical dry evergreen forest on the Coromandel Coast （Pudukottai district） of peninsular India, established in 2003. Among the four sites, Shanmuganathapuram （SP） and Araiyapatti （AP） were much disturbed and the other two sites （Karisakkadu--KR and Maramadakki--MM） were moderately disturbed. We inventoried a total of 3425 lianas representing 37 species of 33 genera and 22 families. Over a decade （2003-2013） liana species richness increased at two sites （MM and SP） and no changes occurred at the other two sites. Liana abundance increased by 210, 211,164 and 162 individuals at sites AP, KR, MM and SP, respectively, and basal area increased （from 1.09 to 1.76 m2 at AP, 0.67 to 0.86 m2 at KR, 1.68 to 2.06 mz at MM, and from 0.44 to 1.06 m2 at SP）. Over a 10-year period, three species （Abrus precatorius, Canavalia virosa, and Cocculus hirsutus） were lost and five species （Gloriosa superba, Ampelocissus tomentosa, Capparis sepiaria, Aganosma cymosa and Tiliacora acuminata） were newly added. Total aboveground biomass increased by 18.5, 0.74, 3.6 and 9.5 Mg ha-1, respectively, at sites AP, KR, MM and SP.展开更多
Background: The effect of forest fire on soil is complex and relatively less understood than its above ground effect.Understanding the effect of fire on forest soils can allow improving management of valuable forest e...Background: The effect of forest fire on soil is complex and relatively less understood than its above ground effect.Understanding the effect of fire on forest soils can allow improving management of valuable forest ecosystems as adequate and proper information is very important for efficient management. We have studied the recovery of soil properties after fire, using a chronosequence approach(two, five and fifteen years after fire and control). Soil samples were collected from each plot of four fire patches(B0, B2, B5 & B15) from three different depths viz. 0–10(Top), 10–20(Middle), and 20–30 cm(Bottom).Results: Soil organic carbon was lower than unburned plots after the fire and could not recover to the level of unburned plot(B0) even in 15 years. Total N, available P, and extractable K were lower 2-years and 5-years after the fire but are higher than unburned plot after 15-years. Available nitrogen(NO_3^- and NH_4^+) remain unchanged or higher than B0 in burned patches. Soil pH, Bulk Density, Water Holding Capacity, and Electrical Conductivity was lower initially after the fire. Forest fires have affected soil properties considerably. The response of soil properties varied with years after fire and soil depth.Conclusion: Forest fires occur very frequently in the study area. Significant quantities of carbon and total nitrogen are lost to the atmosphere by burning of litter, duff, and soil OM. Because nitrogen is one of the most important soil nutrients, the recapture of N lost by volatilization during a fire must receive special attention. Long-term studies are required to better understand the recovery of soil nitrogen.展开更多
Background: Climate-induced challenge remains a growing concern in the dry tropics, threatening carbon sink potential of tropical dry forests. Hence, understanding their responses to the changing climate is of high pr...Background: Climate-induced challenge remains a growing concern in the dry tropics, threatening carbon sink potential of tropical dry forests. Hence, understanding their responses to the changing climate is of high priority to facilitate sustainable management of the remnant dry forests. In this study, we examined the long-term climate-growth relations of main tree species in the remnant dry Afromontane forests in northern Ethiopia. The aim of this study was to assess the dendrochronological potential of selected dry Afromontane tree species and to study the influence of climatic variables (temperature and rainfall) on radial growth. It was hypothesized that there are potential tree species with discernible annual growth rings owing to the uni-modality of rainfall in the region. Ring width measurements were based on increment core samples and stem discs collected from a total of 106 trees belonging to three tree species (Juniperus procera, Olea europaea p. cuspidate and Podocarpus falcatus). Thesubsp. collected samples were prepared, crossdated, and analyzed using standard dendrochronological methods. The formation of annual growth rings of the study species was verified based on successful crossdatability and by correlating tree-ring widths with rainfall. Results: The results showed that all the sampled tree species form distinct growth boundaries though differences in the distinctiveness were observed among the species. Positive and significant correlations were found between the tree-ring widths and rainfall, implying that rainfall plays a vital role in determining tree growth in the region. The study confirmed the formation of annual growth rings through successful crossdating, thus highlighted the potential applicability of dendroclimatic studies in the region. Conclusions: Overall, the results proved the strong linkage between tree-ring chronologies and climate variability in the study region, which further strengthens the potential of dendrochronological studies developing in Ethiopia, and also has great implications for further paleo-climatic reconstructions and in the restoration of degraded lands. Further knowledge on the growth characteristics of tree species from the region is required to improve the network of tree-ring data and quality of the chronology so as to successfully reconstruct historic environmental changes.展开更多
The distribution of many plant species has been shaped by climate changes,and their current phenotypic and genetic variability refect microclimatically suitable habitats.This study relates contemporary climate to vari...The distribution of many plant species has been shaped by climate changes,and their current phenotypic and genetic variability refect microclimatically suitable habitats.This study relates contemporary climate to variability patterns of phenotypic traits and molecular markers in the Argentinean distribution of Anadenanthera colubrina var.cebil,as well as to identify the most relevant phenotypic trait or molecular marker associated with those patterns.Individuals from four populations in both biogeographic provinces,Paranaense and Yungas,were investigated.Multivariate analyses and multiple linear regressions were carried out to determine relationships among phenotypic traits and nuclear microsatellites,respectively,to climatic variables,and to identify the phenotypic traits as well as nuclear microsatellite loci most sensitive to climate.Two and three clusters of individuals were detected based on genetic and phenotypic data,respectively.Only clusters based on genetic data refected the biogeographic origin of individuals.Reproductive traits were the most relevant indicators of climatic effects.One microsatellite locus Ac41.1 appeared to be non-neutral presenting a strong correlation with climate variable temperature seasonality.Our findings show complex patterns of genetic and phenotypic variability in the Argentinean distribution of A.colubrina var.cebil related to the present or contemporary climate,and provides an example for an integrative approach to better understand climate impact on contemporary genetic and phenotypic variability in light of global climate change.展开更多
The Litter nutrient concentrations of N, P, Ca, Mg, K and Na in mature leaves, twigs and reproductive parts and their relationship between senescent and young leaves were investigated in five forest species： Acacia n...The Litter nutrient concentrations of N, P, Ca, Mg, K and Na in mature leaves, twigs and reproductive parts and their relationship between senescent and young leaves were investigated in five forest species： Acacia nilotica, Acacia leucophloea. Tectona grandis, Miliusa tomentosa and Butea monosperma in Indian tropical dry deciduous forest in Western India.. Total dry matter of plant species was recorded and analyzed for N, P, Ca, Mg, K and Na. A. nilotica had the highest concentrations of N in leaf, while ,4. leucophloea had the highest concentrations of Ca and Mg in leaf. The highest concentrations of P in leaf were found in A. nilotica, A. leucophloea and B. monosperma where as lowest in T. grandis and M. tomentosa. No significant differences in K and Na were registered among the species. A marked seasonal variability was ob- served in the concentrations of N, P and K, except for Ca and Mg. Potas- sium is the single element that undergoes leaching and mobilization in all species. Resorped N and P can be used for the production of fresh leaf in the following annual cycle. Nutrient resorption and retranslocation from senescent leaves and litter supports the production of new foliage and increase the fertility of soil.展开更多
The aim of this study was to quantify the dynamics of herbaceous biomass and fine root productivity, and their relationship to stocks of carbon and nitrogen, in the Vertisols of two adjacent watersheds of a seasonally...The aim of this study was to quantify the dynamics of herbaceous biomass and fine root productivity, and their relationship to stocks of carbon and nitrogen, in the Vertisols of two adjacent watersheds of a seasonally dry tropical forest (SDTF) under two different types of ground cover. The two watersheds are located in the county of Iguatu in the State of Ceará, Brazil. The control watershed of 2.1 ha, has been under regeneration for 35 years (RC35), while the second watershed (1.1 ha) was subjected to thinning for a period of 5 years (TC5). The sampled variables were herbaceous shoot biomass, fine roots, gravimetric moisture, the isotope δ13C (‰), total soil carbon (TSC) and total nitrogen (TN) in the 0 - 20, 20 - 40 and 40 - 60 cm layers, between April 2013 and March 2014. To quantify herbaceous shoot biomass, samples were taken monthly. For TSC and TN, the campaigns were held every two months. The data underwent analysis of means and were compared by t-test (p < 0.05). Under TC5, there was an increase in the stocks of TSC and TN of 151 and 137% respectively in the 40 - 60 cm layer, in relation to RC35. The implementation of thinning in a SDFT is seen as a management alternative to be considered in sustainability programs in the semi-arid region, contributing to maximising the production of herbaceous forage for feeding large and small ruminants, and for bee pasture, in addition to increasing the stock of carbon in the soil of SDFT and reducing global warming.展开更多
DDF （dry dipterocarp forest） is importantly deciduous forest type in Thailand since it consists of important tree species for timber products and non-timber products. So, people would like to come to use these produ...DDF （dry dipterocarp forest） is importantly deciduous forest type in Thailand since it consists of important tree species for timber products and non-timber products. So, people would like to come to use these products for daily uses in this forest type. The main aim of this study is to evaluate significant biophysical factors for DDF distribution using factor analysis and to model DDF distribution using ENFA （ecological niche factor analysis）. In this study, 13 watersheds of Ping Basin in northern Thailand were selected as the study site based on availability of forest inventory data in 2007 from DNP （Department of National Parks, Wildlife and Plant Conservation）. Basic biophysical data for data analysis included forest inventory data （179 DDF plots）, 10 climatic data, three topographic data, and one soil data. For identification and evaluation of biophysical factors for DDF distribution using factor analysis, the first three factors, namely DDF-1, DDF-2 and DDF-3, had been extracted with 95.35% of total variance. These three components were used to predict DDF distribution based on HS （habitat suitability） with ENFA. In practice, the results were validated with AVI （absolute validation index） and CVI （contrast validation index） with validated forest inventory dataset. This evaluation shows that DDF-2 model is the best HS data consisting of four physical factors （mean annually temperature, mean monthly maximum temperature, mean monthly minimum temperature, and elevation）, which is able to effectively used for habitat suitability for DDF distribution prediction. It was found that habitat suitability for DDF distribution can be classified into four classes including high suitable habitat, moderate suitable habitat, low suitable habitat, and unsuitable habitat. As a result, DDF distributions with high suitable habitat are highly related with DDF forest inventory plots of DNP. Thus, the obtained output can be further used for DDF rehabilitation according to climate and topographic factors.展开更多
The purposes of this study were, 1) to study the variety of mushrooms grown in the Dry Dipterocarp forest during the year 2008-2009 by Releve method, 2) to study the relationship between ShoreasiamensisMiq. And Ectomy...The purposes of this study were, 1) to study the variety of mushrooms grown in the Dry Dipterocarp forest during the year 2008-2009 by Releve method, 2) to study the relationship between ShoreasiamensisMiq. And Ectomycorrhizal of the Amanitaceae and the Belotaceae families, and 3) study the sequencesof DNAsinsome types of mushrooms in the Amanitaceae and the Balotaceae families by the PCR method. The findings of the study were as thefollowings: First, they were totally 34 types of mush-rooms found in Dry Dipterocarp forest at the Phuphan National Park during the studying period, 2008- 2009. There were 26 types found in both years Amanita hemibapha subsp. javanica Corner & Bas, A. princeps Corner & Bas, A. umbrinolutea (Secr. ex Gillet) Bataille, Termi-tomycesmicro- carpus (Berk. & Br.) R. Heim, T. perforans Heim, T. striatus f. griseus Heim, Boletellusananas (M. A. Curtis) Murrill, B. grisei-purpureus Cor., B. edulis Bull. ex Fr., B. luridus Schaeffer ex Fr., AlpovatrappeiFogel, Can-tharelluscibarius Fries, Craterellusaureus Berk. & Curis, Astraeushygrometricus (Pers.) Morgan, Lactariusaquifluus Peck, L. glaucescens Crossl., L. piperatus (Scop. ex Fr.) S. F. Gray, L. vellereus (Fr.) Fr., L. virescens Fr., R. densifolia (Secr.) Gill, R. emetica (Schaeff. & Fr.) S.F. Gray., R. xelempelina (Schaeff.) Fr., R. foetens (Pers.) Fr., R. rosacea (Pers. ex Secr.) Fries, R. violeipes Quél., R. virescens (Schaeff.) Fries. and those found only in 2009 were Bo-letuscurtisii M. A. Curtis, B. nobilis Peck, RussulaalboareolataHongo, R. cyanoxantha (Schaeff. ex Secr.) Fr. The mushrooms that had been found had significantly relations to the surrounding physical conditions. Second, there was a relationship between the Shoreasiamensis Miq. and Amanita princeps Cor.& Bas., Amanita hemibapha (Berk. & Br.) Sacc. subsp.javanica. Cor. & Bas., Boletus chrysenteron Bull., Boletus griseipurpureus Cor. and Heimiellarestipora (Pat & Bek.) Boedijn. at the intensity of spores 500, 5000, 50000 per each. From the SPSS for ANOVA analysis, the Shoreasiamensis Miq. had no relations to Amanita princeps Cor. & Bas., Amanita hemibapha (Berk. & Br.) Sacc. subsp. javanica. Cor. & Bas., Boletus chrysenteron Bull., Boletus grisei-purpureus Cor. and Heimiellarestipora (Pat & Bek.) Boedijn. in height and circumference growths of Shoreasiamensis Miq. seedlings at the intensity of spores 500, 5000 and 50,000 per each Shoreasiamensis Miq. at 95% level of confidence. Finally, by using the BLASTN computer program toexamine, compare and separate the differences 4 types of mushrooms’ DNA in the Amanitaceae and the Boletaceae families subjected to the PCR method, there were 4 findings i.e. 1342 DNA sbp. of Amanita princeps, 880 DNAs pb. of Boletusnobitis Peck, 1381 DNAs pb. of Boletus edulis Bull. exFr and 758 DNAs bp. of Heimiellaresipora (Pat & Baker).展开更多
基金funded by the Ministry of Environment,Forests and Climate Change(MOEFCC)Government of India under an umbrella grant to Centre for Ecological Sciences,Indian Institute of Science
文摘The phenology of figs （Ficus spp. Moraceae） is being monitored in the dry forests of Mudumalai, southern India and individuals belonging to the genus are marked with unique tag numbers and their vegetative and reproductive phenologies have been monitored since August 2000 on a monthly basis. The influence of abiotic factors on fig phenology and the differences between fig and non- fig phenologies are being examined. The seasonality of different phenophases of fig phenology is also being examined. The maximum intensity of leaf flush occurred in drier months. Fig and non-fig species showed significant differences with expansion and senescence phenophases of leafing. Flowering also occurred in drier months. There were significant differences between fig and non-fig species with reproductive phenophases. As with non-fig species, leafing was influenced by maximum temperatures. Both vegetative and reproductive phenophases were significantly seasonal.
基金funded by Deutscher Akademisher Austausch Dienst(DAAD)Biodiversity Monitoring Transect Analysis(BIOTA)project
文摘Based on 120 stem discs collected during3 months of fieldwork along a 12 km route,the history of fires in the Wari Maro Forest（09 1000 N–02 1000E） over the past century in savanna woodland and dry forest was reconstituted.Three major ecological areas are characterized：one highly burnt zone located between two relative less burnt areas.By analyzing tree rings,246 fire scars were identified.The scars were caused by 51 fire years,occurring at a mean interval of 2.23 years.From 1890 to1965,only 6 years with fires were recorded from sampled trees.Since 1966,no year has passed without fire.The fire frequency point scale reached 14 years.This was the case of Burkea africana,which has been identified as a species tolerant to fire and could be planted to create a natural firewall.In contrast,Anogeissus leiocarpa is highly sensitive to fire,and in a dry forest ecosystem that burns seasonally,it requires a special conservation plan.Two new concepts are described：the rebarking of trees after fire and Mean Kilometer Fire Interval.The first concept was tested with Daniellia oliveri（Rolfe） Hutch ＆ Dalz trees,and the second concept was used to evaluate spatial fire distribution.We demonstrate that savanna woodland and dry forest were subject to a degradation process caused by destructive fires related to vegetation cover clearance and illegal logging.
文摘We carried out this research at Abu-Gaddaf Natural Forest Reserve (ANFR) which is located east of Blue Nile River, in Blue Nile State, Sudan. It aims at exploring tree composition assessing their diversity indices, and ecological importance values. For survey of types and estimation of density of tree species in the forest, we randomly distributed 97 circular sample plots (0.1 hectare (ha)). In each sample plot we identified all trees to the species level, recorded their frequencies and computed species diversity and importance value indices (IVI). A total of 13 tree species, which belong to 12 genera and nine families, were identified in the tree layer of the forest. Mean tree density in ANFR was 116 trees/ha, composed mainly of Boswellia papyrifera (Del.) Hochst. (48), followed by Combretum hartmannianu (19) and Lannea fruticosa (18). Fabaceae was the most common family followed by Combretaceae and Malvaceae. B. papyrifera Delile Hochst was the most abundant while Acacia seyal was the least abundant species. Species richness (R = 1.71), evenness (E = 0.69), dominance (0.24) indices and Simpson’s Index of Diversity (D' = 0.76) suggest a moderate diversity, moderate numbers of individuals in each species and a moderate community stability. The research provides empirical results on diversity and ecological importance value of species, signifies the urging need to safeguard threatened species and to prioritize them for conservation, as well as the need to promote management of abundant species to provide multiple forest ecosystem services.
文摘Background:In tropical dry forests,variation in understory light availability due to season and canopy tree density could be a governing factor in establishment and growth of tree seedlings.Species with varying life history traits are expected to respond differentially to such heterogeneity.We investigated the response of seedlings of four tree species in a tropical day forest in relation to spatiotemporal variability of light.We attempt to explore the role of leaf attributes in explaining intra-and inter-specific variations in relative growth rate.Four study sites,each with three contrasting canopy conditions,were selected along a soil moisture gradient.Seedlings of four tree species(viz.,Acacia catechu,Bridelia retusa,Lagerstroemia parviflora,and Shorea robusta),varying in life history traits,were monitored for seasonal variations in growth traits across canopy condition and sites for 2 years.Results:We observed a larger variation in leaf attributes for pioneer species.A.catechu showed highest mean values for leaf dry matter content,leaf nitrogen concentration,leaf phosphorus concentration,net stomatal conductance,net photosynthetic rate,and relative growth rate in high light conditions.S.robusta and B.retusa demonstrated highest mean values for all the leaf attributes(except leaf dry matter content)in low light conditions.However,intermediate values for leaf attributes were observed in L.parviflora which preferred moderate light conditions.Conclusions:Seasonal variations in light availability at the forest floor appear to play an important role in the establishment and growth of tree seedlings in seasonal dry forests.Leaf attributes can be used to explain intra-and inter-specific variation in response to light availability.Leaf attributes in combinations can be used to predict relative growth rate of tree species in tropical dry environment,which apart from soil moisture is also determined by light availability due to seasonal changes and canopy tree density.
基金Council of Scientific and Industrial Research(New Delhi,India)to S.N.T.Junior and Senior Research Fellowships.
文摘Aims Increasing anthropogenic nitrogen(N)deposition has been claimed to induce changes in species composition and community dynamics.A greenhouse experiment was conducted to examine the effect of increased N availability on growth and functional attributes of seedlings of five tree species with different life history characteristics under varying irradiances.The following questions have been addressed:(i)how do the pioneer and non-pioneer species respond in absolute growth and relative growth rate(RGR)to the interaction of light and nitrogen?(ii)how does the interaction between irradiance and nitrogen availability modulate growth attributes(i.e.functional attributes)?(iii)is there any variation in growth responses between leguminous and non-leguminous species along the light and nitrogen gradients?Methods Seedlings of five tree species(Acacia catechu,Bridelia retusa,Dalbergia sissoo,Lagerstroemia parviflora and Terminalia arjuna)were subjected to twelve combinations of irradiance and N levels.Various growth traits,including height(HT),basal area(BA),whole plant dry biomass(MD),leaf mass per unit area(LMA),leaf area ratio(LAR),net assimilation rate(NAR),RGR,biomass fractions,root-toshoot ratio(R:S)and leaf nitrogen content,were studied to analyse intra-and inter-specific responses to interacting light and N gradients.Important Findings Significant interactions for irradiance and N availability for majority of growth attributes indicates that growth and biomass allocation of seedlings were more responsive to N availability under high irradiance.However,species responded differentially to N addition and they did not follow successional status.Slow growers(B.retusa,a shade-tolerant species and L.parviflora,a light demander)exhibited greater response to N enrichment than the fast growers(A.catechu,D.sissoo and T.arjuna).However,N-mediated increment in growth traits was greater in non-legumes(B.retusa,L.parviflora and T.arjuna)compared with that of legumes(A.catechu and D.sissoo).Allocation of biomass to root was strongly suppressed at the highest N supply across species;however,at high irradiance and high N availability,a greater suppression in R:S ratio was observed for B.retusa.NAR was a stronger determinant of RGR relative to LAR,suggesting its prominent role in increased RGR along increasing irradiances.Overall,a higher growth response of slow-growing species to elevated N levels,particularly the non-pioneers(B.retusa and L.parviflora)suggests that future N deposition may lead to perturbations in competition hierarchies and species composition,ultimately affecting community dynamics in nutrient-poor tropical dry forests.
基金Financial support was obtained from the African Union Commission(through the Pan African University scholarship scheme).
文摘This review attempts to synthesize the available literature on tropical dry forests and their dynamics in the context of climate change and thereby identifies possible gaps and priority areas for further research and management endeavors.Tropical dry forests(TDFs)occur in dryland environments,which are characterized by prolonged periods of dry months.They experience distinct seasonality and high inter-annual variability in climatic variables,particularly rainfall.Despite the enormous ecological and livelihood importance of TDFs,these forests are highly threatened by global changes.So far,they have received far less attention from research and development interventions as compared to the humid tropical forests.Their significance is still overlooked in many countries’national policies.Current modeling frameworks show that drought,precipitation,and temperature are highlighted as strong drivers of tree growth and/or mortality in these forests.Well-valued and sustainably managed TDFs have the potential to contribute to climate change adaptation and mitigation,buffer against erosion and desertification,and contribute to economic development,food security,and poverty alleviation.TDFs suffer notable disregard from research and development strategies.Thus,greater awareness and appropriate policies and investments are needed at various levels to counteract the increasing vulnerability of people,forest ecosystems,and species living in these fragile ecosystems.Further research is also needed to generate knowledge on the status and significances of TDFs and their responses in the face of the changing climate so as to bring their sustainable management to the attention of policymakers and managers.
基金The Ministry of Environment and Forests,Govt.of India(project no.14/26/2005-ERS/RE)Senior Scientist scheme of National Academy of Sciences,India(ref.no.NAS/45/2/09+2 种基金to J.S.S.)Research Associate scheme of Council of Scientific and Industrial Research(award no.09/13(452)/2012-EMR-Ito R.K.C.).
文摘Aims Soil moisture content(SMC)influences establishment,survival and development of plant species and is considered as the most important limiting factor in tropical dry forest(TDF).In this study we attempt to establish the relationship between leaf attributes and of tree saplings in TDF and address the following questions:(i)how are the functional attributes of dominant tree saplings of TDF affected by seasonal changes in SMC at different habitats?,(ii)what is the relationship of functional attributes with each other?,(iii)how are the functional attributes and their plasticity affected by habitat con-ditions?and(iv)can the functional attributes in single or in com-bination predict the growth rate of tree saplings of TDF?The study was conducted on four sites(Hathinala,Gaighat,Harnakachar and Ranitali,listed in order of decreasing SMC)within the tropical dry deciduous forest in northern India.Methods We analysed eight leaf attributes,specific leaf area(SLA);leaf dry matter content(LDMC);leaf nitrogen concentration(leaf N);leaf phosphorus concentration(leaf P);chlorophyll concentration(Chl);mass-based photosynthetic rate(Amass);mass-based stomatal con-ductance(Gsmass);intrinsic water use efficiency(WUEi)and three growth attributes,relative diameter increment(RDI);relative height increment(RHI);relative growth rate(RGR)of the 10 dominant tree saplings(viz.,Acacia catechu,Anogeissus latifolia,Boswellia serrata,Buchanania lanzan,Diospyros melanoxylon,Hardwickia binata,Lagerstroemia parviflora,Lannea coromandelica,Shorea robusta and Terminalia tomentosa)of a TDF and observed the effects of site,season and species for a period of 2 years.Saplings were selected in gradients of deciduousness.Step-wise multiple regression was performed to predict RDI,RHI and RGR from mean values of SMC and leaf attributes.Important Findings All the 11 attributes were interrelated and differed significantly among the 10 saplings.Species response varied across sites and seasons.Across the SMC gradient,the attributes showed variable plasticity that differed across species.Among the 10 saplings,the highly deciduous Boswellia serrata showed the maximum plasticity in seven functional attributes.According to the step-wise multiple regressions,65%variability in RDI and 67%variability in RGR were due to Gsmass,and for RHI,61%variability was due to Amass.SMC and the other attributes,viz.,SLA,Chl,WUEi and LDMC in combination could contribute only for~2-6%of the variability in RDI,RHI and RGR,which indicates that other traits/factors,not accounted in this study are also important in modulating the growth of tree saplings in TDFs.In conclusion,growth of the tree saplings in the tropical dry environment is determined by soil moisture,whereas the response of saplings of different tree species is modulated by alterations in key functional attributes such as SLA,Chl,WUEi and LDMC.
基金supported by the Swedish International Development Agency (Sida)
文摘A study was conducted to examine the natural regeneration of three dry forest species, Lysiloma divaricatum （Jacq.）, Tabebuia ochracea （Cham.） and Lonchocarpus minimiflorus （Donn. Sin.） over a three-year period and to analyze heterogeneity of regeneration in relationship to topographic slope and incidence of light in Chacocente Wildlife Reserve in Nicaragua. Permanent sample plots were established in 2001, and all individuals with height as low as 10 cm and diameter as large as 10 cm were recorded for three consecutive years from 2001 to 2003. The results show that the density of naturally regenerated individuals varied significantly among species, as well as over time. L. minimiflorus and T. ochracea had higher densities compared with L. divaricatum, and the net change in population density was slightly positive for T. ochracea only. Regeneration was more abundant in the gentle and steep slopes under partial exposure of the crown to sunlight, thus resulting in aggregated pattern of distribution, especially for L. minimiflorus and T. ochracea. We concluded that natural regeneration alone is not sufficient to maintain the desired number of stocks of these species, and an immediate restoration measure should be taken to assist the natural regeneration process.
基金Consejo Nacional de Ciencia y Tecnología of México(PhD to L.S.P.,128856 to V.P.T.).
文摘Aims Seasonally tropical dry forests of the Yucatan Peninsula are typically found in sites with nutrient-poor soils because of the recent geologi-cal origin of the region.The landscape is dominated by extensive karstic plates that shape environments where vegetation regenera-tion through seed germination may be limited by the availability of suitable microsites.In this study,we documented the survival and growth of seedlings from three dominant tree species(Bursera simaruba,Piscidia piscipula and Lysiloma latisiliquum)in seasonally tropical dry forests in Yucatan.Specifically,we evaluated the effect of nutrient addition(N and P,separately and in combination)on seedling survival and growth across three sites with differing levels of precipitation.Methods We conducted a nutrient addition experiment,whereby we estab-lished 12 plots of dimensions 10×10 m(100 m^(2))at each site,from which three plots were randomly selected to receive one of four treatments:N addition,P addition,N and P addition and no nutri-ent addition(controls).Prior to treatment application,in each plot,we planted 10 seedlings of each species in October 2010 and sub-sequently conducted surveys of plant growth and survival every 20 days from November 2010 to April 2011.Important Findings Overall,nutrient addition increased seedling survival and the mag-nitude of this effect was similar among sites.We did not observe an additive effect of the N+P treatment on survival.Similarly,we observed a positive effect of nutrient addition on seedling growth,but this effect was contingent upon site;regarding survival,the effects of N and P on seedling growth were not additive.These results suggest that seedling recruitment and growth in the three dominant species of trees in Yucatan are limited by nutrient avail-ability but that the magnitude of this effect,particularly on seedling growth,is specific for species and site.
文摘Introduction:A fundamental challenge to the integrity of tropical dry forest ecosystems is the invasion of nonnative grass species.These grasses compete for resources and fuel anthropogenic wildfires.In 2012,a bulldozer from the Puerto Rico Electric Power Authority cleared a 570-m trail from a state road into a mature dry forest section of Guánica Forest to control a wildfire.We monitored colonization by a non-native invasive grass(Megathyrsus maximus),a highly invasive tree(Leucaena leucocephala),and a native grass(Uniola virgata),as well as natural regeneration,along the bulldozer trail.We determined whether bulldozing facilitated colonization by these species into the forest and the extent of spread.Results:Distance from propagule source and temporal variations strongly influenced colonization by our three focal species.Megathyrsus maximus invaded along the trail from source populations by the state road.The establishment of new colonies of M.maximus seedlings went as far as 570 m inside the forest(i.e.,at the end of the bulldozer trail),but we found most new colonies within 270 m of the road.Leucaena leucocephala exhibited a similar spreading pattern.Before disturbance,Uniola virgata was distributed widely across the forest,but the highest densities were found in areas near the latter portion(>401 m)of the bulldozer trail.Subsequently,the species formed new clumps along more than half of the trail(250 to 570 m),apparently colonizing from undisturbed patches nearby.Conclusions:Bulldozing facilitated the invasion of non-native vegetation.The projected community assemblage will be more fire-prone than before since M.maximus carries fire across the landscape better than U.virgata,emphasizing the capacity of invasive plant colonization to alter local ecological processes after only a single wildfire and bulldoze event.Our results provide a valuable baseline for short-term vegetation response to anthropogenic disturbances in tropical semi-deciduous dry forests.
基金supported by The Steps Towards Sustainable Forest management with the Local Communities in Tigray,Northern Ethiopia(ETH 13/0018)
文摘Arbuscular mycorrhiza fungi(AMF) are vital in the regeneration of vegetation in disturbed ecosystems due to their numerous ecological advantages and therefore are good indicators of soil and ecosystem health at large. This study was aimed at determining how the seasonal, vegetation cover density, edaphic and anthropogenic factors affect AMF root colonization(RC) and spore density(SD)in Desa’a dry Afromontane forest. AMF RC and SD in the rhizosphere of five dominant woody species, Juniperus procera, Olea europaea, Maytenus arbutifolia, Carissa spinarum and Dodonaea angustifolia growing in Desa’a forest were studied during the rainy and the dry seasons in three permanent study vegetation cover density plots(dense, medium, and poor). Each plot(160 x40 m2) has two management practices(fenced and unfenced plots) of area. A 100 g sample of rhizosphere soil from moisturefree composite soil was used to determine spore density.Spore density ranged from 50 to 4467 spores/100 g soil,and all species were colonized by AMF within a range of 4–95%. Glomus was the dominant genus in the rhizosphere of all species. Vegetation cover density strongly affected SD and RC. The SD was significantly higher(p < 0.05) in the poor vegetation cover density than in the other two and lowest in the dense cover; root colonization showed the reverse trend. Management practices significantly(p <0.05) influenced AMF SD and RC, with the fenced plots being more favoured. Seasons significantly(p < 0.05) affected RC and SD. More RC and SD were observed in the wet period than the dry period. Correlating AMF SD and RC with soil physical and chemical properties showed no significant difference(p> 0.05) except for total nitrogen. Disturbance, vegetation cover density, season and total nitrogen are significant factors that control the dynamics and management interventions to maintain the forest health of dry Afromontane forests.
文摘The advent of modem forces and the changes in socio- economic patterns of forest dwellers have increased the pressures on the forests. In order to mitigate such pressures and also to protect the forests and wildlife the model of protected areas networks has shifted and en- hanced such pressures in the unprotected natural forests due to several reasons. Being a low profile category of protected status and continuous human settlements, the present study highlights the case of dry deciduous forests of Sarguja district of Chhattisgarh state of India. The major objec- tives of this study were to quantify the status of forests and wildlife and also to determine the extent of anthropogenic disturbances faced by the dry deciduous forests of central India. Transect and silent drive count methods were used for sampling wildlife and quadrat method was used for sampling vegetation. Besides, the local uses of various forest pro- duces were also studied in view of understanding the people dependency on forests. The forest vegetation, in the study area, was pre-dominated by Shorea robusta, which had Madhuca indica, Diospyrus melanoxylon and Buchnania lanzan as the major companion species. The forest had either the high girth class mature tree species or the saplings. The low vegeta- tion cover and density were due to the high anthropogenic pressures mainly in the form of heavy livestock grazing and collection of etlmo- botanically important species. The study though reveals that the area is not rich in wildlife and the forest is fragmented, the area still supports some important species, which include many rare and endangered plants and animals. The findings of this study have been discussed in view of the management and conservation of the forest and wildlife in the dry deciduous forests.
基金Pondicherry University for financial support received through UGC University fellowship
文摘In 2013, we re-inventoried all lianas （≥1 cm diameter measured at 1.3 m from the rooting point） in four I-ha permanent plots distributed one each in four sites of inland tropical dry evergreen forest on the Coromandel Coast （Pudukottai district） of peninsular India, established in 2003. Among the four sites, Shanmuganathapuram （SP） and Araiyapatti （AP） were much disturbed and the other two sites （Karisakkadu--KR and Maramadakki--MM） were moderately disturbed. We inventoried a total of 3425 lianas representing 37 species of 33 genera and 22 families. Over a decade （2003-2013） liana species richness increased at two sites （MM and SP） and no changes occurred at the other two sites. Liana abundance increased by 210, 211,164 and 162 individuals at sites AP, KR, MM and SP, respectively, and basal area increased （from 1.09 to 1.76 m2 at AP, 0.67 to 0.86 m2 at KR, 1.68 to 2.06 mz at MM, and from 0.44 to 1.06 m2 at SP）. Over a 10-year period, three species （Abrus precatorius, Canavalia virosa, and Cocculus hirsutus） were lost and five species （Gloriosa superba, Ampelocissus tomentosa, Capparis sepiaria, Aganosma cymosa and Tiliacora acuminata） were newly added. Total aboveground biomass increased by 18.5, 0.74, 3.6 and 9.5 Mg ha-1, respectively, at sites AP, KR, MM and SP.
基金the University Grants Commission, New Delhi for providing the financial support for the Ph.D. research through Junior Research Fellowship (UGC letter No. F. 17-115/98 (SA-I) dated-11 June 2013)
文摘Background: The effect of forest fire on soil is complex and relatively less understood than its above ground effect.Understanding the effect of fire on forest soils can allow improving management of valuable forest ecosystems as adequate and proper information is very important for efficient management. We have studied the recovery of soil properties after fire, using a chronosequence approach(two, five and fifteen years after fire and control). Soil samples were collected from each plot of four fire patches(B0, B2, B5 & B15) from three different depths viz. 0–10(Top), 10–20(Middle), and 20–30 cm(Bottom).Results: Soil organic carbon was lower than unburned plots after the fire and could not recover to the level of unburned plot(B0) even in 15 years. Total N, available P, and extractable K were lower 2-years and 5-years after the fire but are higher than unburned plot after 15-years. Available nitrogen(NO_3^- and NH_4^+) remain unchanged or higher than B0 in burned patches. Soil pH, Bulk Density, Water Holding Capacity, and Electrical Conductivity was lower initially after the fire. Forest fires have affected soil properties considerably. The response of soil properties varied with years after fire and soil depth.Conclusion: Forest fires occur very frequently in the study area. Significant quantities of carbon and total nitrogen are lost to the atmosphere by burning of litter, duff, and soil OM. Because nitrogen is one of the most important soil nutrients, the recapture of N lost by volatilization during a fire must receive special attention. Long-term studies are required to better understand the recovery of soil nitrogen.
基金financial supports for this study were obtained from the Pan African University(PAU)African Union(AU)Addis Ababa,Ethiopia as part of its PhD scholarship scheme
文摘Background: Climate-induced challenge remains a growing concern in the dry tropics, threatening carbon sink potential of tropical dry forests. Hence, understanding their responses to the changing climate is of high priority to facilitate sustainable management of the remnant dry forests. In this study, we examined the long-term climate-growth relations of main tree species in the remnant dry Afromontane forests in northern Ethiopia. The aim of this study was to assess the dendrochronological potential of selected dry Afromontane tree species and to study the influence of climatic variables (temperature and rainfall) on radial growth. It was hypothesized that there are potential tree species with discernible annual growth rings owing to the uni-modality of rainfall in the region. Ring width measurements were based on increment core samples and stem discs collected from a total of 106 trees belonging to three tree species (Juniperus procera, Olea europaea p. cuspidate and Podocarpus falcatus). Thesubsp. collected samples were prepared, crossdated, and analyzed using standard dendrochronological methods. The formation of annual growth rings of the study species was verified based on successful crossdatability and by correlating tree-ring widths with rainfall. Results: The results showed that all the sampled tree species form distinct growth boundaries though differences in the distinctiveness were observed among the species. Positive and significant correlations were found between the tree-ring widths and rainfall, implying that rainfall plays a vital role in determining tree growth in the region. The study confirmed the formation of annual growth rings through successful crossdating, thus highlighted the potential applicability of dendroclimatic studies in the region. Conclusions: Overall, the results proved the strong linkage between tree-ring chronologies and climate variability in the study region, which further strengthens the potential of dendrochronological studies developing in Ethiopia, and also has great implications for further paleo-climatic reconstructions and in the restoration of degraded lands. Further knowledge on the growth characteristics of tree species from the region is required to improve the network of tree-ring data and quality of the chronology so as to successfully reconstruct historic environmental changes.
基金supported financially by the Agencia Nacional de Promoción Científica y Tecnológica(AGENCIA)undergrant PICT 2011 N°1795 to M.V.García。
文摘The distribution of many plant species has been shaped by climate changes,and their current phenotypic and genetic variability refect microclimatically suitable habitats.This study relates contemporary climate to variability patterns of phenotypic traits and molecular markers in the Argentinean distribution of Anadenanthera colubrina var.cebil,as well as to identify the most relevant phenotypic trait or molecular marker associated with those patterns.Individuals from four populations in both biogeographic provinces,Paranaense and Yungas,were investigated.Multivariate analyses and multiple linear regressions were carried out to determine relationships among phenotypic traits and nuclear microsatellites,respectively,to climatic variables,and to identify the phenotypic traits as well as nuclear microsatellite loci most sensitive to climate.Two and three clusters of individuals were detected based on genetic and phenotypic data,respectively.Only clusters based on genetic data refected the biogeographic origin of individuals.Reproductive traits were the most relevant indicators of climatic effects.One microsatellite locus Ac41.1 appeared to be non-neutral presenting a strong correlation with climate variable temperature seasonality.Our findings show complex patterns of genetic and phenotypic variability in the Argentinean distribution of A.colubrina var.cebil related to the present or contemporary climate,and provides an example for an integrative approach to better understand climate impact on contemporary genetic and phenotypic variability in light of global climate change.
基金Foundationfor Ecological Security,Anand,Gujarat for financial assistance of this research project
文摘The Litter nutrient concentrations of N, P, Ca, Mg, K and Na in mature leaves, twigs and reproductive parts and their relationship between senescent and young leaves were investigated in five forest species： Acacia nilotica, Acacia leucophloea. Tectona grandis, Miliusa tomentosa and Butea monosperma in Indian tropical dry deciduous forest in Western India.. Total dry matter of plant species was recorded and analyzed for N, P, Ca, Mg, K and Na. A. nilotica had the highest concentrations of N in leaf, while ,4. leucophloea had the highest concentrations of Ca and Mg in leaf. The highest concentrations of P in leaf were found in A. nilotica, A. leucophloea and B. monosperma where as lowest in T. grandis and M. tomentosa. No significant differences in K and Na were registered among the species. A marked seasonal variability was ob- served in the concentrations of N, P and K, except for Ca and Mg. Potas- sium is the single element that undergoes leaching and mobilization in all species. Resorped N and P can be used for the production of fresh leaf in the following annual cycle. Nutrient resorption and retranslocation from senescent leaves and litter supports the production of new foliage and increase the fertility of soil.
文摘The aim of this study was to quantify the dynamics of herbaceous biomass and fine root productivity, and their relationship to stocks of carbon and nitrogen, in the Vertisols of two adjacent watersheds of a seasonally dry tropical forest (SDTF) under two different types of ground cover. The two watersheds are located in the county of Iguatu in the State of Ceará, Brazil. The control watershed of 2.1 ha, has been under regeneration for 35 years (RC35), while the second watershed (1.1 ha) was subjected to thinning for a period of 5 years (TC5). The sampled variables were herbaceous shoot biomass, fine roots, gravimetric moisture, the isotope δ13C (‰), total soil carbon (TSC) and total nitrogen (TN) in the 0 - 20, 20 - 40 and 40 - 60 cm layers, between April 2013 and March 2014. To quantify herbaceous shoot biomass, samples were taken monthly. For TSC and TN, the campaigns were held every two months. The data underwent analysis of means and were compared by t-test (p < 0.05). Under TC5, there was an increase in the stocks of TSC and TN of 151 and 137% respectively in the 40 - 60 cm layer, in relation to RC35. The implementation of thinning in a SDFT is seen as a management alternative to be considered in sustainability programs in the semi-arid region, contributing to maximising the production of herbaceous forage for feeding large and small ruminants, and for bee pasture, in addition to increasing the stock of carbon in the soil of SDFT and reducing global warming.
文摘DDF （dry dipterocarp forest） is importantly deciduous forest type in Thailand since it consists of important tree species for timber products and non-timber products. So, people would like to come to use these products for daily uses in this forest type. The main aim of this study is to evaluate significant biophysical factors for DDF distribution using factor analysis and to model DDF distribution using ENFA （ecological niche factor analysis）. In this study, 13 watersheds of Ping Basin in northern Thailand were selected as the study site based on availability of forest inventory data in 2007 from DNP （Department of National Parks, Wildlife and Plant Conservation）. Basic biophysical data for data analysis included forest inventory data （179 DDF plots）, 10 climatic data, three topographic data, and one soil data. For identification and evaluation of biophysical factors for DDF distribution using factor analysis, the first three factors, namely DDF-1, DDF-2 and DDF-3, had been extracted with 95.35% of total variance. These three components were used to predict DDF distribution based on HS （habitat suitability） with ENFA. In practice, the results were validated with AVI （absolute validation index） and CVI （contrast validation index） with validated forest inventory dataset. This evaluation shows that DDF-2 model is the best HS data consisting of four physical factors （mean annually temperature, mean monthly maximum temperature, mean monthly minimum temperature, and elevation）, which is able to effectively used for habitat suitability for DDF distribution prediction. It was found that habitat suitability for DDF distribution can be classified into four classes including high suitable habitat, moderate suitable habitat, low suitable habitat, and unsuitable habitat. As a result, DDF distributions with high suitable habitat are highly related with DDF forest inventory plots of DNP. Thus, the obtained output can be further used for DDF rehabilitation according to climate and topographic factors.
文摘The purposes of this study were, 1) to study the variety of mushrooms grown in the Dry Dipterocarp forest during the year 2008-2009 by Releve method, 2) to study the relationship between ShoreasiamensisMiq. And Ectomycorrhizal of the Amanitaceae and the Belotaceae families, and 3) study the sequencesof DNAsinsome types of mushrooms in the Amanitaceae and the Balotaceae families by the PCR method. The findings of the study were as thefollowings: First, they were totally 34 types of mush-rooms found in Dry Dipterocarp forest at the Phuphan National Park during the studying period, 2008- 2009. There were 26 types found in both years Amanita hemibapha subsp. javanica Corner & Bas, A. princeps Corner & Bas, A. umbrinolutea (Secr. ex Gillet) Bataille, Termi-tomycesmicro- carpus (Berk. & Br.) R. Heim, T. perforans Heim, T. striatus f. griseus Heim, Boletellusananas (M. A. Curtis) Murrill, B. grisei-purpureus Cor., B. edulis Bull. ex Fr., B. luridus Schaeffer ex Fr., AlpovatrappeiFogel, Can-tharelluscibarius Fries, Craterellusaureus Berk. & Curis, Astraeushygrometricus (Pers.) Morgan, Lactariusaquifluus Peck, L. glaucescens Crossl., L. piperatus (Scop. ex Fr.) S. F. Gray, L. vellereus (Fr.) Fr., L. virescens Fr., R. densifolia (Secr.) Gill, R. emetica (Schaeff. & Fr.) S.F. Gray., R. xelempelina (Schaeff.) Fr., R. foetens (Pers.) Fr., R. rosacea (Pers. ex Secr.) Fries, R. violeipes Quél., R. virescens (Schaeff.) Fries. and those found only in 2009 were Bo-letuscurtisii M. A. Curtis, B. nobilis Peck, RussulaalboareolataHongo, R. cyanoxantha (Schaeff. ex Secr.) Fr. The mushrooms that had been found had significantly relations to the surrounding physical conditions. Second, there was a relationship between the Shoreasiamensis Miq. and Amanita princeps Cor.& Bas., Amanita hemibapha (Berk. & Br.) Sacc. subsp.javanica. Cor. & Bas., Boletus chrysenteron Bull., Boletus griseipurpureus Cor. and Heimiellarestipora (Pat & Bek.) Boedijn. at the intensity of spores 500, 5000, 50000 per each. From the SPSS for ANOVA analysis, the Shoreasiamensis Miq. had no relations to Amanita princeps Cor. & Bas., Amanita hemibapha (Berk. & Br.) Sacc. subsp. javanica. Cor. & Bas., Boletus chrysenteron Bull., Boletus grisei-purpureus Cor. and Heimiellarestipora (Pat & Bek.) Boedijn. in height and circumference growths of Shoreasiamensis Miq. seedlings at the intensity of spores 500, 5000 and 50,000 per each Shoreasiamensis Miq. at 95% level of confidence. Finally, by using the BLASTN computer program toexamine, compare and separate the differences 4 types of mushrooms’ DNA in the Amanitaceae and the Boletaceae families subjected to the PCR method, there were 4 findings i.e. 1342 DNA sbp. of Amanita princeps, 880 DNAs pb. of Boletusnobitis Peck, 1381 DNAs pb. of Boletus edulis Bull. exFr and 758 DNAs bp. of Heimiellaresipora (Pat & Baker).
