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极端干旱与食草昆虫对草原群落的交互作用受干旱模式的影响
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作者 Ye Luo Yuguang Ke +8 位作者 Hongqiang Wang Chong Xu Qian Gu Qiang Yu melinda d.smith Rajabboy Madrimov Nuriddin Samatov Wei Yang Honghui Wu 《Journal of Plant Ecology》 SCIE CSCD 2024年第3期128-140,共13页
极端干旱和食草昆虫可以共同影响植物群落,并且它们的交互作用可能受到干旱模式的影响。然而,目前尚缺乏相关的观测证据。本研究以半干旱草原为研究对象,通过控制实验探讨了不同极端干旱模式与食草昆虫的交互作用对植物群落的影响。实... 极端干旱和食草昆虫可以共同影响植物群落,并且它们的交互作用可能受到干旱模式的影响。然而,目前尚缺乏相关的观测证据。本研究以半干旱草原为研究对象,通过控制实验探讨了不同极端干旱模式与食草昆虫的交互作用对植物群落的影响。实验设置了3种干旱处理,分别为对照(自然降雨量)、慢性干旱(生长季5–8月减少66%降雨量)和急性干旱(6–7月完全无降雨)。在各小区设置了两种食草昆虫处理,分别是有食草昆虫和无食草昆虫。结果表明,食草昆虫和极端干旱及二者的交互作用对物种丰富度无显著影响。食草昆虫缓解了慢性干旱对总盖度的负面影响,而这种缓解作用在急性干旱下较低。食草昆虫对慢性干旱带来的负面效应具有更强的缓解作用,这主要是因为食草昆虫导致慢性干旱下适口性较高的杂类草(具有较低叶片碳含量、叶片干物质含量,以及较低叶片淀粉、钙、镁、锰含量)的大幅降低,进而降低了禾草的负面效应。上述结果表明,干旱和食草昆虫的交互作用受干旱模式的影响。通过调节植物的适口性来控制食草昆虫的采食行为,可以减轻极端干旱对草原生态系统的影响。 展开更多
关键词 急性干旱 慢性干旱 半干旱草原 食草昆虫 极端气候
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内蒙古草原优势物种光合速率对极端干旱的响应
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作者 Yalong Shi Yuanbo Cao +8 位作者 Honghui Wu Chong Xu Qiang Yu Xiaoan Zuo Xingguo Han melinda d.smith Alan K.Knapp Chengjie Wang Guodong Han 《Journal of Plant Ecology》 SCIE CSCD 2024年第3期5-15,共11页
评估极端干旱对优势植物物种光合速率(Pn)的影响对于我们理解极端干旱影响生态系统功能的机制至关重要。极端干旱可能由降雨量减少或降雨频率减少造成。这两种不同模式的极端干旱可能造成不同的影响。此外,不同草原类型可能对这两种极... 评估极端干旱对优势植物物种光合速率(Pn)的影响对于我们理解极端干旱影响生态系统功能的机制至关重要。极端干旱可能由降雨量减少或降雨频率减少造成。这两种不同模式的极端干旱可能造成不同的影响。此外,不同草原类型可能对这两种极端干旱模式表现出不同的敏感性。然而,目前尚不清楚这两种极端干旱模式对草原优势植物物种Pn的影响有何差异,以及在不同草原类型这两种不同模式的极端干旱的效应是否改变。为此,我们于2014年在内蒙古草原两个不同类型的草原(荒漠草原vs.典型草原)站点各进行了一项多年的极端干旱(CHR:将生长季期间每次降雨事件的降雨量减少66%vs.INT:完全排除生长季内一段较短时间的降水)模拟实验。于2017年的7月和8月,我们在这两个草原站点各测量了两种优势物种的Pn。结果发现,CHR和INT均显著降低了优势物种的Pn。无论草原类型如何,INT对Pn造成的负面影响都更大。在荒漠草原,极端干旱对Pn的负面影响普遍大于典型草原,尤其是对于CHR处理下的羊草(Leymus chinensis)。这些结果表明,与降雨量减少相比,降雨频率减少所引起的极端干旱对Pn的负面影响更大。草地类型可能会改变极端干旱模式效应的程度,但不会改变其方向。这些发现强调了应对未来极端干旱的草原生态系统管理应考虑极端干旱模式和草地类型的影响。 展开更多
关键词 极端气候 荒漠草原 典型草原 极端干旱模式 季节性干旱
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Herbivores alleviate the negative effects of extreme drought on plant community by enhancing dominant species 被引量:2
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作者 Chong Xu Yuguang Ke +4 位作者 Honghui Wu melinda d.smith Nathan P.Lemoine Weiguo Zhang Qiang Yu 《Journal of Plant Ecology》 SCIE CSCD 2021年第6期1030-1036,共7页
Aims Both extreme drought and insect herbivores can suppress plant growth in grassland communities.However,most studies have examined extreme drought and insects in isolation,and there is reason to believe that insect... Aims Both extreme drought and insect herbivores can suppress plant growth in grassland communities.However,most studies have examined extreme drought and insects in isolation,and there is reason to believe that insects might alter the ability of grasslands to withstand drought.Unfortunately,few studies have tested the interactive effects of extreme drought and insect herbivores in grassland communities.Methods Here,we tested the drought–herbivore interactions using a manipulative experiment that factorially crossed extreme drought with the exclusion of insect herbivores in a temperate semiarid grassland in Inner Mongolia.Important Findings Our results demonstrated that both extreme drought and insect herbivores separately decreased total plant cover.When combined,insect herbivores reduced the impact of drought on total cover by increasing the relative abundance of drought-resistant dominant species.Our results highlight that the negative effect of extreme drought on total plant cover could be alleviated by maintaining robust insect herbivore communities. 展开更多
关键词 extreme drought insect herbivores pant community cover semiarid grassland dominant species
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Genotypic diversity of a dominant C_(4) grass across a long-term fire frequency gradient
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作者 Cynthia C.Chang melinda d.smith 《Journal of Plant Ecology》 SCIE 2013年第6期448-458,共11页
Aims and Methods Diversity-disturbance research has focused on community diversity,but disturbance frequency could impact diversity within species as well,with important consequences for community diversity and ecosys... Aims and Methods Diversity-disturbance research has focused on community diversity,but disturbance frequency could impact diversity within species as well,with important consequences for community diversity and ecosystem function.We examined patterns of genetic diversity of a dominant grass species,Andropogon gerardii,in native North American tallgrass prairie sites located in eastern Kansas that have been subjected to a gradient of fire frequency treatments(burned every 1,2,4 or 20 years)since the 1970s.In addition,we were able to assess the relationships between genetic diversity of A.gerardii,species diversity and productivity across this range of fire frequencies.Important Findings We found no significant relationships between genetic diversity of A.gerardii at the local scale(1 m^(2) plot level)and disturbance frequency(burned 2 to 32 times over a 38-year period).However,at the site level(i.e.across all plots sampled within a site,~100 m^(2))there were differences in genotype richness and composition,as well as genomic dissimilarity among individuals of A.gerardii.Genotype richness was greatest for the site burned at an intermediate(4-year)frequency and lowest for the infrequently(20-year)burned site.In addition,genotypes found in the frequently burned sites were more similar from each other than expected by random chance than those found in the infrequently burned sites.Genotype composition of A.gerardii was not significantly different between the frequently burned sites(annual vs.2 year)but did differ between frequently burned and infrequently burned sites(1 and 2 year vs.4 and 20 year,etc.).Together,these results suggest site-level ecological sorting of genotypes in intact prairie across a broad gradient of disturbance frequencies,likely driven by alterations in environmental conditions.Frequent fire promotes the abundance of dominant grass species,reduces plant community diversity and impacts ecosystem processes such as productivity.Our study suggests that genetic diversity within dominant grass species also may be affected by disturbance frequency,which could have important implications for how species are able to respond to disturbance. 展开更多
关键词 Andropogon gerardii disturbance frequency genetic relatedness genetic-species diversity relationship genotype richness intermediate disturbance hypothesis PRODUCTIVITY tallgrass prairie
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Long-term effects of fire frequency and season on herbaceous vegetation in savannas of the Kruger National Park,South Africa
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作者 melinda d.smith Brian Wvan Wilgen +6 位作者 Catherine E.Burns Navashni Govender Andre L.F.Potgieter Sandy Andelman Harry C.Biggs Judith Botha Winston S.W.Trollope 《Journal of Plant Ecology》 SCIE 2013年第1期71-83,共13页
Aims:The long-term effects of changing fire regimes on the herbaceous component of savannas are poorly understood but essential for understanding savanna dynamics.We present results from one of the longest running(>... Aims:The long-term effects of changing fire regimes on the herbaceous component of savannas are poorly understood but essential for understanding savanna dynamics.We present results from one of the longest running(>44 years)fire experiments in savannas,the experimental burn plots(EBPs),which is located in the Kruger National Park(South Africa)and encompasses four major savanna vegetation types that span broad spatial gradients of rainfall(450–700 mm)and soil fertility.Methods:Herbaceous vegetation was sampled twice in the EBPs using a modified step-point method,once prior to initiation of the experiment(1954)and again after 44–47 years.Different combinations of three fire frequency(1-,2-and 3-year return intervals)and five season(before the first spring rains,after the first spring rains,mid-summer,late summer and autumn)treatments,as well as a fire exclusion treatment,were applied at the plot level(;7 ha each),with each treatment(n=12 total)replicated four times at each of the four sites(n=192 plots total).The effects of long-term alterations to the fire regime on grass community structure and composition were analyzed separately for each site.Important Findings:Over the 44+years duration of the experiment,fires were consistently more intense on sites with higher mean annual rainfall(>570 mm),whereas fires were not as intense or consistent for sites with lower and more variable rainfall(<510 mm)and potentially higher herbivory due to greater soil fertility.Because the plots were open to grazing,the impacts of herbivory along with more variable rainfall regimes likely minimized the effects of fire for the more arid sites.As a consequence,fire effects on grass community structure and composition were most marked for the higher rainfall sites and generally not significant for the more arid sites.For the high-rainfall sites,frequent dry season fires(1-to 3-year return intervals)resulted in high grass richness,evenness and diversity,whereas fire exclusion and growing season fires had the lowest of these measures and diverged the most in composition as the result of increased abundance of a few key grasses.Overall,the long-term cumulative impacts of altered fire regimes varied across broad climatic and fertility gradients,with fire effects on the grass community decreasing in importance and herbivory and climatic variability likely having a greater influence on community structure and composition with increasing aridity and soil fertility. 展开更多
关键词 CLIMATE fire intensity GRASS HERBIVORY soil fertility
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