Invasive plant species may significantly alter plant species community composition and structure thereby negatively impacting on ecosystem services. Their impacts on plant communities may be both direct and indirect. ...Invasive plant species may significantly alter plant species community composition and structure thereby negatively impacting on ecosystem services. Their impacts on plant communities may be both direct and indirect. The direct effects may include a reduction in the abundance and diversity of palatable plant species that constitute important forage for livestock, wildlife, and medicines for the local communities. Declines in ecosystem resilience are of the notable indirect effects of invasive species. The aim of this study was to assess the impacts of a plant species, copper leaf (<em>Acalypha fruticosa</em>) on floral diversity and abundance at Chemeron, Baringo County in Kenya. The study was guided by three questions: What is the plant composition in terms of grasses, herbs, shrubs, and trees in the study area? Are there any variations in plant abundance between the two sites (sites with and without <em>Acalypha fruticosa</em>)? Are there variations in plant species diversity between the two study sites? Two sites (one with <em>A. fruticosa</em> and another two without this invasive species) were selected within the Chemeron Research Centre. Two belt transects measuring 100 m × 20 m on each site were laid parallel to each other. Plant samples were collected from five 1 m × 1 m quadrats that were laid at intervals of 20 m. The plant species or specimens were identified to the species level using available taxonomic keys. Various indices including Shannon-Wiener (<em>H</em>’), Evenness Index, Richness Index and Simpson’s Index of Diversity Index (SDI) were calculated. All the diversity, richness and evenness indices were considerably higher in the site without <em>A. fruticosa</em> compared to that where this invasive species was present. Higher <em>H’</em> (3.14 to 3.21) and SDI (0.93 to 0.94) values were noted in sites without the invasive species compared to <em>H</em>’ (2.11 to 2.20) and SDI (0.77 to 0.85) in sites with <em>A. fruticosa</em> present. Out of the 47 plant species identified, 39 and 20 of them occurred in the site without and with <em>A. fruticosa</em>, respectively. Further, there were more grasses (<em>Aristida keniensis</em>, <em>Cynodon dactylon</em>, <em>Brachiaria lucrantha</em>, <em>Eragrostis racemosa</em>, and <em>Enteropogon macrostachyus</em>) in the site without <em>A. fruticosa</em> compared to that with the invasive plant. The plants were also more evenly distributed in the site without <em>A. fruticosa</em> compared to that where the invasive plant was present. We conclude that <em>A. fruticosa</em> has a significant effect on plant species abundance and diversity as well as distribution. Its removal created a favourable environment for the growth of a variety of grasses. We therefore recommend to the agro-pastoralists and rangeland managers that <em>A. fruticosa</em> be mechanically removed by uprooting from grazing lands so as to increase forage availability and quality in the rangelands of South-Baringo.展开更多
Semi-arid wooded-shrublands are important and critical habitats that provide breeding and feeding grounds for a variety of bird species, some of which are endangered, vulnerable or threatened with extinction. Habitat ...Semi-arid wooded-shrublands are important and critical habitats that provide breeding and feeding grounds for a variety of bird species, some of which are endangered, vulnerable or threatened with extinction. Habitat type and size influence abundance and diversity of birds globally and particularly in developing countries that are characterized by rapid human population growth and haphazard urban, agricultural and industrial development. The objective of this study was to assess avian and habitat diversity at Chemeron, a semi-arid land in the northern rangelands of Kenya. The study was guided by four questions: What kind of Habitat types are present at Chemeron study area? What kind of birds are found at Chemeron area? What is the conservation status of birds found at Chemeron area? What are the functional feeding guilds of birds that are found in the study area? How does the habitat type influence bird species abundance and diversity at Chemeron? Four 2-km long transects radiating from a central point within the study area were selected for a ground survey of birds that was conducted on foot. The surveys were conducted between 06:30 and 09:30 and 16:00 and 18:00 from October 2019 to April 2020. Bird species were observed and identified to the species level using high-resolution binoculars, field guidebooks and available taxonomic keys. Our surveys documented two main habitat types: <em>Acacia-Balanites-Boscia</em> woodlands dominated by <em>Acacia senegal</em>,<em> Acacia mellifera</em>, <em>Acacia nilotica</em>, <em>Boscia angustifolia</em>, and <em>Balanites aegyptica</em>. The second kind of habitat consisted of the invasive <em>Acalypha fruticosa</em> and <em>Indigofera arrecta</em> with <em>Acacia reficiens-Acacia brevispica</em> overstorey. A total of 53 bird species were sighted and identified the vulnerable Yellow necked spurfowl (<em>Francolinus leucoscepus</em>). Seventy-nine percent of the birds were sighted as singles or in pairs except for the gregarious white browed sparrow weaver (<em>Plocepasser mahali</em>), <em>Apus caffer</em>, <em>Numida meleagris</em>, <em>Streptopelia senegalensis</em>, <em>Dinemellia dinemelli</em> and <em>Corythaxoides leucogaster</em>. Significant differences in the various species diversity indices among the six transects were observed (p < 0.05). Approximately 60% of the birds belong to the insectivorous and omnivorous feeding guild. Charcoal burning and uncontrolled harvesting of wood are the major threats to the avian habitats in the study area. The high diversity of bird species in the study area can be attributed to the varied diversity of habitats that provide feeding, nesting, refuge and breeding grounds for the birds. From the foregoing findings, we can conclude that the ASALs of Baringo South offer ample habitat for a large number of bird species including the vulnerable Yellow necked spurfowl. The variations in various bird diversity indices can be attributed to the observed heterogeneity of habitats in the study area. We recommend wise use of rangeland resources and protection of critical avian habitats within the ASALs. Efforts should be geared towards livelihoods diversification and empowerment of the Lake Bogoria communities. This will reduce the pressure on the wooded shrublands that is widespread in the study area.展开更多
Hydrological dynamics affect water levels and thus affecting ecosystem structure and functions. Lake levels in tropical ecosystems affect phosphorous input through runoff from adjacent watersheds. The resultant biolog...Hydrological dynamics affect water levels and thus affecting ecosystem structure and functions. Lake levels in tropical ecosystems affect phosphorous input through runoff from adjacent watersheds. The resultant biological community, water and sediment quality of the lakes due to water level changes is a reflection of the geology of the area and the anthropogenic activities in the watershed. The study conducted between January 2018 and December 2019 was to explore relationships between the phosphorous input and Water Level Fluctuations (WLF) recorded by Water Resource Authority (WRA). Lake water samples were analyzed in the laboratory for phosphorous using molybdenum blue-ascorbic method and recorded using spectrophotometer. Chlorophyll-<em>a</em> was determined by extracting a filtered sample with 15 ml acetone and incubating overnight and thereafter read using a double beam spectrophotometer. Total Suspended Solids (TSS) was determined by filtering 200 ml of a water sample and dried overnight at 105<span style="white-space:nowrap;">°</span>C. The lowest and highest phosphorous concentrations recorded were 0.2 mg/l and 0.42 mg/l at NST7 and NST2, respectively. Measurements of Chlorophyll-<em>a</em> were 0.32 mg/l and 0.42 mg/l at NST9 and NST2, respectively. Secchi transparency measurements were 32.9 cm at NST3 and 84 cm at NST1. The highest and lowest TSS concentrations were 0.14 mg/l and 0.13 mg/l at NTS1 and NST8, respectively. The hydrodynamic regime in most tropical lakes plays a significant role in the re-reaction of phosphorous that consequently influences productivity. Tropical lakes have extreme lake level fluctuations which accelerate the production process. The influence of water level changes on aquatic productivity is crucial in most tropical lakes and should be taken into consideration when assessing the environmental impacts.展开更多
文摘Invasive plant species may significantly alter plant species community composition and structure thereby negatively impacting on ecosystem services. Their impacts on plant communities may be both direct and indirect. The direct effects may include a reduction in the abundance and diversity of palatable plant species that constitute important forage for livestock, wildlife, and medicines for the local communities. Declines in ecosystem resilience are of the notable indirect effects of invasive species. The aim of this study was to assess the impacts of a plant species, copper leaf (<em>Acalypha fruticosa</em>) on floral diversity and abundance at Chemeron, Baringo County in Kenya. The study was guided by three questions: What is the plant composition in terms of grasses, herbs, shrubs, and trees in the study area? Are there any variations in plant abundance between the two sites (sites with and without <em>Acalypha fruticosa</em>)? Are there variations in plant species diversity between the two study sites? Two sites (one with <em>A. fruticosa</em> and another two without this invasive species) were selected within the Chemeron Research Centre. Two belt transects measuring 100 m × 20 m on each site were laid parallel to each other. Plant samples were collected from five 1 m × 1 m quadrats that were laid at intervals of 20 m. The plant species or specimens were identified to the species level using available taxonomic keys. Various indices including Shannon-Wiener (<em>H</em>’), Evenness Index, Richness Index and Simpson’s Index of Diversity Index (SDI) were calculated. All the diversity, richness and evenness indices were considerably higher in the site without <em>A. fruticosa</em> compared to that where this invasive species was present. Higher <em>H’</em> (3.14 to 3.21) and SDI (0.93 to 0.94) values were noted in sites without the invasive species compared to <em>H</em>’ (2.11 to 2.20) and SDI (0.77 to 0.85) in sites with <em>A. fruticosa</em> present. Out of the 47 plant species identified, 39 and 20 of them occurred in the site without and with <em>A. fruticosa</em>, respectively. Further, there were more grasses (<em>Aristida keniensis</em>, <em>Cynodon dactylon</em>, <em>Brachiaria lucrantha</em>, <em>Eragrostis racemosa</em>, and <em>Enteropogon macrostachyus</em>) in the site without <em>A. fruticosa</em> compared to that with the invasive plant. The plants were also more evenly distributed in the site without <em>A. fruticosa</em> compared to that where the invasive plant was present. We conclude that <em>A. fruticosa</em> has a significant effect on plant species abundance and diversity as well as distribution. Its removal created a favourable environment for the growth of a variety of grasses. We therefore recommend to the agro-pastoralists and rangeland managers that <em>A. fruticosa</em> be mechanically removed by uprooting from grazing lands so as to increase forage availability and quality in the rangelands of South-Baringo.
文摘Semi-arid wooded-shrublands are important and critical habitats that provide breeding and feeding grounds for a variety of bird species, some of which are endangered, vulnerable or threatened with extinction. Habitat type and size influence abundance and diversity of birds globally and particularly in developing countries that are characterized by rapid human population growth and haphazard urban, agricultural and industrial development. The objective of this study was to assess avian and habitat diversity at Chemeron, a semi-arid land in the northern rangelands of Kenya. The study was guided by four questions: What kind of Habitat types are present at Chemeron study area? What kind of birds are found at Chemeron area? What is the conservation status of birds found at Chemeron area? What are the functional feeding guilds of birds that are found in the study area? How does the habitat type influence bird species abundance and diversity at Chemeron? Four 2-km long transects radiating from a central point within the study area were selected for a ground survey of birds that was conducted on foot. The surveys were conducted between 06:30 and 09:30 and 16:00 and 18:00 from October 2019 to April 2020. Bird species were observed and identified to the species level using high-resolution binoculars, field guidebooks and available taxonomic keys. Our surveys documented two main habitat types: <em>Acacia-Balanites-Boscia</em> woodlands dominated by <em>Acacia senegal</em>,<em> Acacia mellifera</em>, <em>Acacia nilotica</em>, <em>Boscia angustifolia</em>, and <em>Balanites aegyptica</em>. The second kind of habitat consisted of the invasive <em>Acalypha fruticosa</em> and <em>Indigofera arrecta</em> with <em>Acacia reficiens-Acacia brevispica</em> overstorey. A total of 53 bird species were sighted and identified the vulnerable Yellow necked spurfowl (<em>Francolinus leucoscepus</em>). Seventy-nine percent of the birds were sighted as singles or in pairs except for the gregarious white browed sparrow weaver (<em>Plocepasser mahali</em>), <em>Apus caffer</em>, <em>Numida meleagris</em>, <em>Streptopelia senegalensis</em>, <em>Dinemellia dinemelli</em> and <em>Corythaxoides leucogaster</em>. Significant differences in the various species diversity indices among the six transects were observed (p < 0.05). Approximately 60% of the birds belong to the insectivorous and omnivorous feeding guild. Charcoal burning and uncontrolled harvesting of wood are the major threats to the avian habitats in the study area. The high diversity of bird species in the study area can be attributed to the varied diversity of habitats that provide feeding, nesting, refuge and breeding grounds for the birds. From the foregoing findings, we can conclude that the ASALs of Baringo South offer ample habitat for a large number of bird species including the vulnerable Yellow necked spurfowl. The variations in various bird diversity indices can be attributed to the observed heterogeneity of habitats in the study area. We recommend wise use of rangeland resources and protection of critical avian habitats within the ASALs. Efforts should be geared towards livelihoods diversification and empowerment of the Lake Bogoria communities. This will reduce the pressure on the wooded shrublands that is widespread in the study area.
文摘Hydrological dynamics affect water levels and thus affecting ecosystem structure and functions. Lake levels in tropical ecosystems affect phosphorous input through runoff from adjacent watersheds. The resultant biological community, water and sediment quality of the lakes due to water level changes is a reflection of the geology of the area and the anthropogenic activities in the watershed. The study conducted between January 2018 and December 2019 was to explore relationships between the phosphorous input and Water Level Fluctuations (WLF) recorded by Water Resource Authority (WRA). Lake water samples were analyzed in the laboratory for phosphorous using molybdenum blue-ascorbic method and recorded using spectrophotometer. Chlorophyll-<em>a</em> was determined by extracting a filtered sample with 15 ml acetone and incubating overnight and thereafter read using a double beam spectrophotometer. Total Suspended Solids (TSS) was determined by filtering 200 ml of a water sample and dried overnight at 105<span style="white-space:nowrap;">°</span>C. The lowest and highest phosphorous concentrations recorded were 0.2 mg/l and 0.42 mg/l at NST7 and NST2, respectively. Measurements of Chlorophyll-<em>a</em> were 0.32 mg/l and 0.42 mg/l at NST9 and NST2, respectively. Secchi transparency measurements were 32.9 cm at NST3 and 84 cm at NST1. The highest and lowest TSS concentrations were 0.14 mg/l and 0.13 mg/l at NTS1 and NST8, respectively. The hydrodynamic regime in most tropical lakes plays a significant role in the re-reaction of phosphorous that consequently influences productivity. Tropical lakes have extreme lake level fluctuations which accelerate the production process. The influence of water level changes on aquatic productivity is crucial in most tropical lakes and should be taken into consideration when assessing the environmental impacts.
