呼伦贝尔沙化草地人工固沙植物种间生态位关系研究   总被引：2，自引：1，他引：2  

张金鹏  高菲  卢欣石 《草地学报》2010,18(1):26-30

采用样方法对呼伦贝尔地区沙化草地不同恢复年限人工播种固沙区进行调查,并计算其主要植物的重要值、生态位体积及生态位重叠值,以研究呼伦贝尔沙化草地人工固沙植物群落特征及演替状况。结果表明:人工固沙植物冰草(Agropyron pectinatum(Bieb.)Beauv.)的平均生态位体积在时间尺度上,呈持续增加趋势,是改良沙化草地的优良草种;小麦(Triticum aestivum L.)与小叶锦鸡儿(Caragana microphylla Lam.)、冰草与羊柴(Hedysa-rum laeveMaxim)生态位重叠值为0.9213和0.7512,在演替过程中具较强的竞争作用。自然恢复植物与人工播种植物间,多数生态位重叠值不高。自然恢复多年生植物大针茅(Stipa grandis P.Smirn.)、糙隐子草(C1eistogenes squarrosa(Trin.)Keng)等逐渐出现,表明该地区植被群落结构向稳定共存的人工-天然植被群落结构方向发展。  相似文献   

Generalist feeding strategies in Arctic freshwater fish: A mechanism for dealing with extreme environments          下载免费PDF全文

Sarah M. Laske  Amanda E. Rosenberger  Mark S. Wipfli  Christian E. Zimmerman 《Ecology of Freshwater Fish》2018,27(3):767-784

Generalist feeding strategies are favoured in stressful or variable environments where flexibility in ecological traits is beneficial. Species that feed across multiple habitat types and trophic levels may impart stability on food webs through the use of readily available, alternative energy pools. In lakes, generalist fish species may take advantage of spatially and temporally variable prey by consuming both benthic and pelagic prey to meet their energy demands. Using stomach content and stable isotope analyses, we examined the feeding habits of fish species in Alaska's Arctic Coastal Plain (ACP) lakes to determine the prevalence of generalist feeding strategies as a mechanism for persistence in extreme environments (e.g. low productivity, extreme cold and short growing season). Generalist and flexible feeding strategies were evident in five common fish species. Fish fed on benthic and pelagic (or nektonic) prey and across trophic levels. Three species were clearly omnivorous, feeding on fish and their shared invertebrate prey. Dietary differences based on stomach content analysis often exceeded 70%, and overlap in dietary niches based on shared isotopic space varied from zero to 40%. Metrics of community‐wide trophic structure varied with the number and identity of species involved and on the dietary overlap and niche size of individual fishes. Accumulation of energy from shared carbon sources by Arctic fishes creates redundancy in food webs, increasing likely resistance to perturbations or stochastic events. Therefore, the generalist and omnivorous feeding strategies employed by ACP fish may maintain energy flow and food web stability in extreme environments.  相似文献   

河南卢氏油松种子园开花物候重叠指数     

张华新  卢国美  李占和 《河北林果研究》1995,(3)

应用Ａｓｋｅｗ和Ｂｌｕｓｈ的针叶树种子园开花物候重叠指数模型，在１９８７～１９８９年，对卢氏油松种子园３１个无性系的花期物候观侧数据，做了异交、自交的重叠指数和种子园重叠指数的计算，为新建种子园时亲本的优化组配和现有种子园的去劣疏伐提供了重要参数。  相似文献   

人工草地群落组成与土壤中速效氮磷的关系   总被引：15，自引：1，他引：14  

王刚  蒋文兰 《草地学报》1995,3(1):42-48

通过对白三叶和多年生黑麦草生物量在上壤速效磷氛比例梯度上变化模式的分析，验证了Tilman的群落组成变化的矿质营养比例学说。“以两种牧草生物量分别对土壤速效磷和速效氮二元线性回归的结果表明：磷和氮分别是白三叶和多年生黑麦草生长的限制因子。由此，二者可实现在土壤营养元素上的生态位分化而得以在人工草地群落中共存。  相似文献   

甘肃景泰北部干旱荒漠区封育沙地植物生态位研究     

冯宜明  杨萌萌  祁效杰 《草原与草坪》2016,(5):58-63

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。  相似文献   

Competitive effects between rainbow trout and Atlantic salmon in natural and artificial streams          下载免费PDF全文

Aimee Lee S. Houde  Andrew D. Smith  Chris C. Wilson  Pedro R. Peres‐Neto  Bryan D. Neff 《Ecology of Freshwater Fish》2016,25(2):248-260

Competition with non‐native species may impede the restoration of native species, but differences in competitive abilities among intraspecific native populations may make some populations more suitable for reintroduction than others. Here, juvenile Atlantic salmon (Salmo salar) from two allopatric populations (LaHave and Sebago) being used for reintroduction into Lake Ontario were placed into two natural stream sites differing in the presence of ecologically similar rainbow trout (Oncorhynchus mykiss). We assessed the effects of competition in the natural streams on fitness‐related traits and habitat use of the Atlantic salmon. We then compared these effects to those observed in artificial streams from a previous study. Atlantic salmon in natural streams had reduced fitness‐related traits that were associated with suboptimal microhabitats in the presence of rainbow trout, but utilised optimal microhabitats in their absence. In the presence of rainbow trout, the two Atlantic salmon populations exhibited comparable recapture proportions to each other, but the individuals from the Sebago population had better performance (body size and condition) than those from the LaHave population. Responses of both Atlantic salmon populations to competition with rainbow trout were generally similar in both direction and magnitude when compared to results from the artificial stream study. The combined results suggest that native species restoration efforts should be focused on candidate populations that are ecologically suitable to reintroduction environments, as well as on suitable habitats that do not contain exotic competitors. Moreover, this study highlights the value of controlled experiments in artificial environments for predicting fitness‐related performance in natural environments.  相似文献   

Food partitioning between sympatric gerbils (genus Meriones) in arid conditions of the western part of the Caspian Depression     

Magomedrasul Magomedov  Mamlakat Magomedova  Zalmo Magomedova 《Arid Land Research and Management》2017,31(4):472-484

There are many patterns of coexistence in communities, including partitioning based on spatial, temporal, or food niches. This study considered the partitioning of food between two ecologically similar and sympatric species, the tamarisk gerbil and the midday gerbil, in the Terek-Kuma Lowland of the Republic of Daghestan. The qualitative and quantitative characteristics of the diets of both gerbils were revealed. The species have relatively wide diets; the tamarisk gerbil’s diet consisted of forty-six plant species, and the midday gerbil’s diet consisted of fifty plant species within the study areas. Thirty plant species were present in the diets of the two gerbils. The dietary breadths of both gerbils were similar. The dietary overlap of the two gerbils ranged from low to moderate (average Pianka’s dietary overlap index, 0.476?±?0.08). Finally, under conditions in which food resources are sufficient, the moderate abundance of gerbils and the high diversity of habitats and microhabitats in the study areas allow these two species of gerbils to coexist in a common location.  相似文献   

基于旅游生态位理论的旅游竞争态势研究——以西双版纳为例     

陈娟 《绿色大世界》2013,(4):271-273

引用生态位态势理论和生态位扩充模型，以西双版纳为案例分析点，对西双版纳的游客量生态位和旅游收入生态位以及旅游生态位扩充率进行了测算，结果表明：西双版纳旅游目前的发展状况存在明显的旅游生态位扩充现象，为研究旅游地发展情况提供一个新的理论和分析视角。  相似文献   

Competitive interactions among multiple non‐native salmonids and two populations of Atlantic salmon          下载免费PDF全文

Aimee Lee S. Houde  Chris C. Wilson  Bryan D. Neff 《Ecology of Freshwater Fish》2015,24(1):44-55

Competitive interactions with non‐native species can have negative impacts on the conservation of native species, resulting in chronic stress and reduced survival. Here, juvenile Atlantic salmon (Salmo salar) from two allopatric populations (Sebago and LaHave) that are being used for reintroduction into Lake Ontario were placed into semi‐natural stream tanks with four non‐native salmonid competitors that are established in Ontario streams: brown trout (S. trutta), rainbow trout (Oncorhynchus mykiss), Chinook salmon (O. tshawytscha) and coho salmon (O. kisutch). Brown trout and rainbow trout reduced the survival and fitness‐related traits of Atlantic salmon, whereas Chinook salmon and coho salmon had no impact on these traits. These data support theories on ecological niche overlap and link differences in observed aggression levels with competitive outcomes. Measurements of circulating hormones indicated that the Atlantic salmon were not chronically stressed nor had a change in social status at the 10‐month time point in the semi‐natural stream tanks. Additionally, the Sebago population was better able to coexist with the non‐native salmonids than the LaHave population. Certain populations of Atlantic salmon may thus be more suitable for some environments of the juvenile stream phase for the reintroduction into Lake Ontario.  相似文献   

The morphology–diet relationship and its role in the coexistence of two species of annual fishes          下载免费PDF全文

Friedrich W. Keppeler  Luis Esteban K. Lanés  Ana S. Rolon  Cristina Stenert  Pablo Lehmann  Martin Reichard  Leonardo Maltchik 《Ecology of Freshwater Fish》2015,24(1):77-90

Annual fishes, which inhabit temporary pools with extremely limited habitat complexity and niche availability, display remarkable sexual dimorphism, rapid growth, and enormous investment into reproduction, all traits associated with high energy requirement. This study tests three hypotheses for two syntopic annual fishes (Austrolebias minuano and Cynopoecilus fulgens) found in six wetlands of southern Brazil: (i) considerable morphological differences result in low dietary overlap, (ii) sexual dimorphism in both species leads to intraspecific diet segregation, and (iii) dietary richness increases during ontogenetic development, and is narrower in C. fulgens than A. minuano due to morphological limitations imposed by reduced size. The diet of 82 A. minuano and 211 C. fulgens individuals was analyzed over two annual cycles. The morphology was characterized by 26 measurements covering the entire body of both species. There was no evidence of morphological specialization related to food competition and the diet of A. minuano and C. fulgens showed high overlap. High food availability, high predator abundance, and high connectivity of adjacent wetlands are likely the main mechanisms allowing coexistence of both species. Within species, sexual dimorphism did not result in a decrease in dietary overlap, which reinforces the idea that morphological differences between the sexes did not evolve as a mechanism to decrease food competition. Large A. minuano did not have a more diverse diet than the smaller C. fulgens; however, increase in body size allowed both species to ingest larger prey. Morphological variability in both species was mainly related to ontogenetic development and reproduction.  相似文献