呼伦贝尔草甸草原区主要植物种群生态位特征与物种多样性对封育年限响应

采用Levins生态位指数、Pianka生态位重叠指数和物种多样性指数,分析草甸草原区主要植物种群生态位对封育年限的响应特征。结果表明：退化草地实施封育措施后,群落中主要植物种群生态位宽度发生变化,未封育（对照区）样地以多年生草本植物蒲公英生态位宽度最大;封育年限为4和13年时,生态位宽度最大的物种均为展枝唐松草;封育年限为5、6、8和10年时,生态位宽度最高的物种依次是羊草、麻花头、囊花鸢尾和贝加尔针茅;退化草地实施封育后,物种间生态位重叠指数值集中在0.6~0.9,而未封育样地物种生态位重叠指数值在0.0~0.3;随着封育年限的增加,生态位重叠指数总平均值表现出先增加后降低的变化趋势,其中未封育（对照区）样地主要植物种群生态位重叠指数总平均值最低,封育5年时,主要植物种群生态位重叠指数总平均值最大,为0.68;封育草地的主要植物种群的生态位重叠指数平均值较未封育（对照区）样地增加了40.76%~93.68%;封育年限为5年时,Shannon-Wiener多样性指数、Simpson多样性指数和Margalef丰富度指数、Pielou均匀度指数最大,分别比未封育（对照区）增加了45.46%、16.51%、45.80%和23.38%。封育后,群落多样性、丰富度和均匀度显著增加,并且植物种间竞争加剧,但在封育5年后,随着封育年限的增加,多样性、丰富度以及均匀度逐渐降低,导致生态位分化,种间竞争减缓,群落趋于稳定。因此,从物种多样性角度出发,该区封育时间不宜过长,在封育5年后,可采取适当利用,保护群落多样性。     

藏中矿区植物种群生态位特征研究

本文采用样方法以藏中矿区的3种群落为研究对象,对样地的植物种群进行系统调查,并计算其主要植物的重要值、生态位宽度和生态位重叠值。结果表明,不同群落类型优势种非常明显,并且具有较高的生态位宽度和生态位重叠。高寒矿区各植物优势种群与其它种群之间竞争激烈,群落结构极不稳定,群落可能正处于正向演替和逆向演替的拐点。     

甘肃亚高山云杉人工林下植物种群生态位特征

根据野外110个样方的调查数据,应用Levins、Shannon-Wiener生态位宽度指数和Levins生态位重叠指数对甘肃亚高山云杉(Picea asperata)人工林下30个种(包括15种灌木和15种草本植物)的生态位特征进行定量分析。结果表明,灌木针刺悬钩子(Rubus pungens)、箭竹(Sinarundinaria nitida)、秀丽莓(Rubus amabilis)、草本东方草莓(Fragaria orientalis)、鸭茅(Dactylis glomerata)和紫花碎米荠(Cardamine tangutorum)的生态位宽度较大,表明这些物种适应能力强,分布范围广,倾向于泛化种。生态位宽的种群可能产生较小的生态位重叠,生态位较窄的种群间也会产生较大的生态位重叠,生态位宽度与生态位重叠程度无相关性。总体上看,亚高山云杉人工林下物种间生态位重叠程度均较小,种间竞争并不激烈。从生态响应来看,灌木层的红桦(Betula albo-sinensis)幼苗和草本层的老鹳草(Geranium wilfordii)发展性最强,今后可能会发展为云杉人工林下的优势种群。     

间作苜蓿棉田节肢动物群落生态位及时间格局

应用生态位理论对间作苜蓿棉田节肢动物群落进行了系统研究,探讨了棉苜间作棉田主要害虫和天敌的关系.间作苜蓿棉田天敌生态位宽度大于对照棉田,天敌群落在整个调查期内发生的时间长;而对照棉田主要害虫的生态位宽度大于间作苜蓿棉田,害虫对棉花的危害时间长、程度重.间作苜蓿棉田的主要天敌蜘蛛类、多异瓢虫与害虫生态位重叠度大于对照棉田,天敌能更有效地控制棉花害虫的危害.在时间变化过程中,节肢动物群落的时间格局分化明显,将间作苜蓿棉田节肢动物群落在时间动态中的变化分为4个阶段,并结合气候、物候变化,分析了各阶段内主要害虫和天敌的发生特点.     

不同退化梯度下大尤尔都斯高寒草原植物种群生态位特征

采用Levins生态位宽度指数(BL_i)和Pianka生态位重叠指数(Q_(ik)),测定不同退化梯度下巴音布鲁克大尤尔都斯高寒草原17种主要植物的生态位宽度及生态位重叠。结果表明,未退化阶段,优势种紫花针茅(Stipapurpurea)的生态位宽度较高,轻度退化与中度退化阶段其生态位宽度减小,重度退化阶段又上升,其它物种根据群落结构变化生态位宽度发生变化。在不同退化梯度下均出现生态位较窄的种群生态位重叠较大的现象,物种间生态位重叠的变化是由种间生态学特性差异与草地退化对种间关系影响共同造成的。研究显示,在巴音布鲁克大尤尔都斯高寒草原,过度放牧导致草地退化,物种生态位重叠总体相对较低。     

围栏封育对温性草甸草原植物群落构成及生态位特征的影响

为明确温性草甸草原群落构成和生态位对围栏封育的响应,运用了Levins生态位指数和Pianka生态位重叠指数以及物种多样性指数分析围栏内外植物种对资源的利用情况和种间竞争情况。结果表明:围栏封育显著促进退化草地植被恢复,植被地上生物量和地下生物量分别较对照提高255.06%,51.06%;物种多样性与丰富度分别增加了10.36%,10.34%。围封样地内生态位宽度排名前2位的植物为囊花鸢尾和羊草,生态位宽度值分别为0.921和0.873;自由放牧样地生态位宽度排在前2的植物为蒲公英和寸草苔,生态位宽度值依次为0.912和0.791。围栏封育可以显著提高草地生产力,并且对物种多样性也有一定的促进作用,是应对退化温性草甸草原恢复的有效措施;与自由放牧相比,围栏封育增加了群落植物种整体生态位重叠值和种间竞争。     

Population dynamics of three lizard species from the genus Sceloporus: short‐term changes in demographic parameters

Most demographic studies focus on numerical changes that occur within populations across years. However, typically studies at an interannual scale do not provide information on the particular times of the year (particular months or seasons) when rates of survival, recruitment, or migration increase or decrease due to physiological, behavioral or ecological processes. These monthly or seasonal changes in demographic parameters may lead to substantial variations in population abundance. In this study, we collected capture–mark–recapture data on 3 species of lizards of the genus Sceloporus (Sceloporus torquatus, Sceloporus grammicus and Sceloporus megalepidurus) found in ecologically similar habitats to examine potential changes in demographic rates among 3 different climatic seasons: rainy, cold‐dry and warm‐dry seasons. We tested different hypotheses about the effect of these seasons on survival, recruitment of new adults, and temporary emigration. We found that during the season with severe thermal constraints, the cold‐dry season, survival of S. torquatus decreased markedly. We also detected a considerable increase in the recruitment rate of S. grammicus during the rainy season, when these lizards are establishing territories and finding mates. In contrast, we found no evidence of intra‐annual changes in the rate of temporary emigration. In addition, we calculated abundance and population growth rates for each species and for each season. Our study represents a significant contribution to the understanding of intra‐annual demographic variation in lizards.     

Differences in diet between two rodent species,Mastomys natalensis and Gerbilliscus vicinus,in fallow land habitats in central Tanzania

Differences in the ecological niche requirements among rodent species competing in the same habitat may result from differences in the use of one to three resources: space, time and food or some combination of these. Alternatively, differences in resource use utilization among animal species may simply reflect availability of food, and when food is limited, different animal species compete. In this study, the diet of two rodent pest species, Mastomys natalensis and Gerbilliscus vicinus, coexisting in fallow land in central Tanzania were studied to assess the degree of diet differentiation among them. Dietary niche breadth of G. vicinus was greater than that of M. natalensis in all stages of the maize cropping seasons. The rodent species studied overlapped considerably in the food items consumed ranging from niche overlap (O_jk) of 0.77–0.89. Grains/seeds featured high in the diet of M. natalensis while plant material occurrence was high in G. vicinus. These two food categories may have contributed to differences in diet partitioning, which may, in turn, facilitate their coexistence in fallow land.     

Food habits and trophic resource partitioning among three mormyrid fishes from man-made Lake Ayame,Ivory Coast

Feeding habits and trophic relationships among three mormyrid species (Petrocephalus bovei, Marcusenius ussheri and Marcusenius furcidens) were assessed in the man-made Lake Ayame in Ivory Coast. The index of preponderance combining the occurrence and weight percentages of the identified prey items showed that these three mormyrid species mainly feed on invertebrates, especially aquatic insects. Petrocephalus bovei mainly feeds on chaoborid larvae, whereas both Marcusenius species preferentially feed on chironomid larvae. This segregation of food items associated with the relative abundance of chironomid larvae may reduce interspecific competition between these three fish species, and may therefore allow their coexistence. Horn’s food overlap index revealed highly significant similarities in the trophic spectrum between both Marcusenius species, and for the dry as well as the rainy season.     

Evaluation of habitat requirements of small rodents and effectiveness of an ecologically‐based management in a hantavirus‐endemic natural protected area in Argentina

Hantavirus pulmonary syndrome is a severe cardio pulmonary disease transmitted to humans by sylvan rodents found in natural and rural environments. Disease transmission is closely linked to the ecology of animal reservoirs and abiotic factors such as habitat characteristics, season or climatic conditions. The main goals of this research were: to determine the biotic and abiotic factors affecting richness and abundance of rodent species at different spatial scales, to evaluate different methodologies for studying population of small rodents, and to describe and analyze an ecologically‐based rodent management experience in a highly touristic area. A 4‐year study of small rodent ecology was conducted between April 2007 and August 2011 in the most relevant habitats of El Palmar National Park, Argentina. Management involved a wide range of control and prevention measures, including poisoning, culling and habitat modification. A total of 172 individuals of 5 species were captured with a trapping effort of 13 860 traps‐nights (1.24 individuals/100 traps‐nights). Five rodent species were captured, including 2 hantavirus‐host species, Oligoryzomys nigripes and Akodon azarae. Oligoryzomys nigripes, host of a hantavirus that is pathogenic in humans, was the most abundant species and the only one found in all the studied habitats. Our results are inconsistent with the dilution effect hypothesis. The present study demonstrates that sylvan rodent species, including the hantavirus‐host species, have distinct local habitat selection and temporal variation patterns in abundance, which may influence the risk of human exposure to hantavirus and may have practical implications for disease transmission as well as for reservoir management.     

Competitor densities,habitat, and weather: effects on interspecific interactions between wild deer species

There is a growing interest on the potential interplay between weather, habitat, and interspecific competition on population dynamics of wild herbivores. Favorable environmental conditions may buffer the negative effects of competition; conversely, competition may be expected to be stronger under harsh environmental conditions. We investigated relationships between competitor abundance, weather, and habitat cover on density and local distribution of a medium-sized herbivore, the roe deer Capreolus capreolus, as well as its spatial overlap with fallow deer Dama dama in a Mediterranean protected area. Over 11 years (2007–2017), roe deer density was not affected by spring–summer rainfall in the previous year and decreased with increasing density of fallow deer in the previous year. Hence, over the considered temporal scale, results supported a major role of competition over weather in influencing population trends of roe deer. At a finer spatial scale, roe deer occupancy was negatively affected by local abundance of fallow deer, especially in “poorer” habitats. We found a slight support for a positive effect of fallow deer density on interspecific spatial overlap. Moreover, fine-scale spatial overlap between deer species increased with decreasing rainfall in spring–summer. Fallow deer were introduced to our study area in historical times and their role as superior competitors over roe deer has been found also in other study areas. We suggest a potential role of harsh weather conditions during the growing season of vegetation (i.e. scarce rainfall) in triggering the potential for ecological overlap, emphasizing the negative effects of interspecific competition.     

Midsummer Trophic Overlap Between Guanaco and Sheep in Patagonian Rangelands

Diet overlap estimation among species is important to understand interspecific interactions. Through these interactions, one species may extinguish others through competition or adapt through mechanisms such as resource partitioning. The introduction of domestic herbivores in a native assemblage may introduce competition for resources with wild herbivores. In southern Patagonian steppes, guanaco (Lama guanicoe) populations are increasing after a drastic demise during the past century. This is occurring in protected areas and extensive ranching areas for sheep, and in the latter ranchers have rising concerns regarding competition. In this observational study, we measured diet overlap, food selection and preferences, and niche width for guanaco and sheep to compare use of food resources during the summer season. Feces were analyzed through microhistological technique to determine sheep and guanaco diets. Diets of guanaco and sheep were dominated by tussock grass (Festuca gracillima, sheep > 60%, guanaco > 50%), the most abundant plant species. Although food niche widths, measured through Levin’s Index, were narrow, guanaco presented the broadest niche (P < 0.001). Of the 17 identified plant species present in guanaco and sheep diets, 5 were always selected by both ungulates and 1 was always avoided at the four study sites. Overlap between diets was high (> 0.90), evidencing potential competition. In addition, diet overlap coupled with our results of small variation in use and selectivity of food resources suggest the absence of resource partitioning. Therefore, both species might share resources or coexist, possibly due to high availability or spatial distribution of food resources and guanaco resilience to cope with numerically dominant competition from sheep. These findings offer new insight into the understanding of these species’ interactions. It is also a management challenge to emerging wild and domestic herbivores interactions, as well as livestock production concerns at large.     

黄土丘陵区不同立地条件下植物种群生态位研究

运用改进的Levins生态位宽度指数和Pianka生态位重叠指数,通过对不同立地条件下样带的比较,分析了主要植物种群在不同立地条件下的生态位变化以及种间关系、群落结构对立地条件的响应。结果表明,草地群落建群种本氏针茅的生态位宽度在4种立地条件下都表现为最大值,非建群种的生态位宽度随环境条件的改变呈较大的波动性。生态位重叠指数表明,生态位较宽的物种与其它物种间存在较大的生态位重叠,但在一定的立地条件下,生态位较窄的物种之间也存在着较大的生态位重叠,这种现象是种群对有限环境资源激烈竞争的体现;不同种间生态位重叠随立地条件的变化格局存在较大差异,这种差异是由植物种间生物生态学特性和需求差异造成的;但同一种对在不同立地条件下生态位重叠的变化是立地条件对种间关系影响的结果。总体来说,在黄土丘陵沟壑区,由于环境条件的影响,物种生态位重叠相对较低。     

云雾山天然草地30年恢复演替过程中优势草种生态位动态

为探究云雾山天然草地30年恢复演替过程中优势草种的生态位动态,通过典型样方调查,运用Levins和Pianka公式分别对封育5年、9年、14年、18年和30年天然草地的主要物种生态位进行了分析。结果表明：不同封育年限草地的物种组成与群落类型具有明显差异,阿尔泰狗哇花（Heteropappus altaicus）、大针茅（Stipa grandis）、二裂委陵菜（Potentilla bifurca）和百里香（Thymus mongolicus）4个种群生态位总宽度较大,且在5个不同封育年限草地均有出现。云雾山原建群种长芒草（Stipa bungeana）生态位宽度也较大,但在封育30年样方中未发现其分布。不同封育年限各物种生态位宽度排序和其总宽度排序并不相同,封育5年、9年和14年的草地中生态位宽度最大的分别是长芒草、甘肃蒿（Artemisia gansuensis）和猪毛蒿（A.scoparia）,封育18年和30年草地大针茅最大。随着封育年限增加,优势物种的生态位宽度出现波动,大针茅的生态位宽度随封育年限增加呈现“升-降-升”的动态变化,封育5~18年,长芒草生态位宽度变化表现为先降后升,甘青针茅（S.przewalskyi）只在封育30年样地出现,但其生态位宽度仅次于大针茅。种群间生态位重叠与不同封育年限草地种群生态位宽度无线性关系,封育9年草地种群间的生态位重叠指数均值最大,封育14年和30年草地的生态位重叠指数均值呈递增趋势。随着封育年限的增加,草地生态系统逐渐得到恢复,种间竞争也随之增加。     

中新天津生态城夏季啮齿类的空间生态位

2008年夏季对中新天津生态城的啮齿动物进行调查,采用Shannon-Wiener生态位宽度指数和Pianka生态位重叠指数对啮齿动物空间生态位进行了研究。结果表明,在捕获的5种啮齿动物中,小家鼠和黑线姬鼠的空间生态位宽度指数最高,分别为0.97和0.78;褐家鼠(Bi=0.58)和黑线仓鼠(Bi=0.51)次之;大仓鼠(Bi=0.36)最低。除了黑线姬鼠与其他4种啮齿动物两两之间空间生态位重叠指数均较小(C_P<0.50)外,其他4种啮齿动物两两之间均较高(C_P>0.50)。黑线仓鼠与褐家鼠空间生态位几乎完全重叠(C_P=0.99),在10对啮齿动物中,共有7对之间的空间生态位重叠指数大于0.70。由此可见,生态城啮齿动物之间存在资源竞争,主要原因是生态城是典型的盐碱湿地,可利用资源不丰富,使得动物分布相对集中,增加种间竞争。     

甘肃景泰北部干旱荒漠区封育沙地植物生态位研究

利用Levins生态位宽度公式和Pianka生态位重叠公式,对甘肃省景泰县北部沙生植被主要植物种在不同恢复方式下的生态位宽度和生态位重叠进行计测分析。结果表明:在自然恢复沙地灌木层中,沙蒿的生态位宽度最大,BL值为0.966,其次是驴驴蒿,BL值为0.935。人工+自然恢复沙地灌木层中,仍是沙蒿的生态位宽度最大,BL值为0.962,其次是花棒和沙拐枣,BL值分别为0.900和0.897;在自然恢复沙地草被层中,禾草的生态位宽度最大,其次是五星蒿,BL值分别是0.989、0.959。人工+自然恢复沙地草本中,五星蒿的生态位宽度最大,其次是刺蓬,BL值分别是0.952、0.942;自然恢复沙地灌木种群间生态位重叠最大的是荒漠锦鸡儿与白沙蒿,NO值为1。人工+自然恢复沙地灌木种群间生态位重叠最大的是柠条与沙拐枣,NO值为0.980;具有较宽生态位的五星蒿、刺蓬、禾草、沙米等草本间均有较大的生态位重叠,生态位宽度和生态位重叠之间不是直接的线形关系。     

五台山蓝花棘豆群落优势种群生态位研究

采用Shannon-Wiener和Levins指数以及Petraitis特定重叠指数对五台山蓝花棘豆群落的18个优势种群的生态位宽度和生态位重叠进行了研究。结果表明,蓝花棘豆和小江菊的生态位最宽,这是由于它们对环境的广泛适应性。建群种如蓝花棘豆、地榆和披针苔草之间重叠值最大,且它们与其他15个种群的特定重叠值远小于15个种群与它们的特定重叠值。生态位宽度相似的物种之间特定重叠值较大,如蓝花棘豆与地榆;生态学特性相似的物种之间的特定重叠值较大,如细叶鸢尾与石竹。有8个种对之间存在完全特定重叠。18个优势种群之间不存在完全普遍重叠,这主要与它们对水分和光照的适应性不同有关。     

生态位理论在天然草场群落演替及健康状况评价中的应用

采用样方法对宁夏盐池不同年限天然草场进行调查,并计算该区植被Levins生态位宽度指数、生态位总宽度指数及Pianka生态位重叠指数,以期了解该区天然草场健康状态及植被群落的演替状况。结果表明:降雨的多少直接决定了半干旱区天然草场平均生态位宽度的大小,在研究初期生态位宽度值排在前列的主要是丝叶山苦荬(Lxeris chinensis var.graminifolia(Ledeb.)H.C.Fu)、猫头刺(Oxytropis aciphylla Ledeb)、赖草(Leymus secalinus(Georgi)Tzvel.);中期则为新疆猪毛菜(Salsola sinkiangensis A.J.Li)>猫头刺>老瓜头(Cynanchum komarovii Al.);末期生态位宽度值排在前列的依次是阿尔泰狗娃花(Heteropappus altaicus(Willd.)Novopokr.)>丝叶山苦荬>老瓜头。天然草场在群落演替过程中是以远志(Polygala tenuifolia Willd.)和老瓜头等主要物种为稳定演替物种,伴随着丝叶山苦荬和猫头刺等物种的衰落,以及达乌里胡枝子(Lespedeza davurica(Laxm.)Schindl.)和阿尔泰狗娃花的兴起。研究中期由于降雨量的减少导致天然草场自身状态最差,但随着年限的延长,天然草场植被群落在演替过程中生态位发生分化,草场逐渐实现自我优化。     

玛曲高寒沙化草地植物生态位特征研究

研究高寒沙化草地植物群落特征和演替状况,对恢复生态环境、提高草地生产力具有重要意义。本文采用样方法对玛曲高寒沙化草地20个样地的植物种群进行系统调查,并计算其主要植物的重要值、生态位宽度和生态位重叠值。结果表明:该草地当前的优势种为异针茅(Stipa aliena);生态位宽度最大的是亚优势种高山唐松草(Thalictrum alpinum)和乳浆大戟(Euphorbia esula),为0.974,而优势种异针茅仅0.941,说明优势种并不具有最强适应能力和竞争力,在群落中的地位也不稳定;生态位宽度大的物种之间具有大的生态位重叠值,其中高山唐松草和乳浆大戟生态位重叠值最大,达0.987,与其他种群之间的竞争也较强,表明高寒沙化草地的演替方向将是杂类草取代禾草的优势地位,如不及时治理,草地将进一步退化。     

山西浊漳河北源湿地草本植物群落优势种生态位与种间关系

以山西浊漳河北源湿地草本植物群落调查为基础,通过生态位指数测度、方差比率法、χ2检验、联结系数AC、Pearson相关系数检验对16个优势种群进行了生态位和种间关联的分析。结果表明,1)藨草(Scirpus triqueter)、头穗莎草(Cyperus glomeratus)、水蓼(Polygonum hydropiper)的生态位宽度值相对较大,在研究区域内具有泛化种倾向;2)120个种对间的生态位重叠指数低,55%的种对之间不存在重叠,种间竞争弱;3)群落内植物整体关联度为显著负相关(P0.05),χ2检验与Pearson相关系数检验的正负关联比(分别为0.52和0.15)均小于1,负关联的种对数多于正关联,且大多数种间关联程度不显著(P0.05),说明浊漳河北源湿地草本植物群落结构简单,物种间相互作用较弱,处于演替初期阶段;4)物种间的生态位重叠指数与联结系数AC、Pearson相关系数存在着显著的正相关关系(P0.05),且Pearson相关系数的拟合效果优于AC联结系数。本研究有利于更好地认识优势种种间的相互关系及群落的动态特征,了解浊漳河北源湿地利用现状,为湿地生态恢复提供理论依据。