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。     

贺兰山西坡森林主要种群关系及其动态研究

本文从种群的相关与生态位重叠研究入手,揭示了贺兰山西坡森林生态系统中主要种群的相互作用程度和性质,从而找到了该区森林群落发生发展的内在动力。为进一步合理利用贺兰山森林资源、充分发挥其以理水为主导的系统功能奠定了种群关系的研究基础,也提供了可能的调节途径。     

侧多食跗线螨天敌种类调查及其应用前景研究

据调查,侧多食跗线螨的天敌种类有16种,隶属于7个科,其优势种为塔六点蓟马和拟长毛钝绥螨。通过生态位研究,从理论上阐述了应用天敌昆虫控制侧多食跗线螨的可行性。通过天敌昆虫保护与应用技术研究,提出了增加天敌昆虫种群数量和有效控制侧多食跗线螨的技术途径。     

小麦生长中后期2种麦蚜垂直分布及生态位的研究

研究了小麦生长中后期麦长管蚜和禾谷缢管蚜的垂直分布及生态位,结果表明,2种麦蚜在麦田混合发生,种群动态相似,主要分布于小麦穗部和中上部叶片,时间生态位和空间生态位宽度值接近,生态位相似性比例分别高达0.8513和0.8418,禾谷缢管蚜的空间生态位重叠值大于麦长管蚜,麦长管蚜的时间生态位重叠值大于禾谷缢管蚜。     

Assessing sensitivity to climate change and drought variability of a sand dune endemic lizard

Bioclimatic models aimed assessing a species’ sensitivity to climate change incorporate mean shifts in climate variables; however the more acute threat to the persistence of species may result from increased frequency of extreme climatic events, including increased duration and severity of droughts. Here we assess climate-change sensitivity using niche modeling that unlike bioclimatic modeling incorporates both climate variables as well as other habitat features that constrain a species’ distribution. We analyzed the effects of potential increases in drought frequency for an endangered, sand dune-restricted lizard, a species restricted to a narrowly occurring substrate and so unable to move up-slope or pole-ward to track climate shifts. Our niche modeling results indicated only minor losses to the area of suitable niche space at lower levels of modeled climate change; at the most severe climate shifts we tested the area of suitable niche space reduced by slightly more than 50%. However, extrapolating the potential impacts of reduced rainfall on drought periodicity and intensity showed a more immediate and acute impact on the lizard’s populations. Drought duration projections coupled with landscape fragmentation resulted in rapid losses of suitable niche space, beginning in the more arid portion of the lizard’s range and extending into more moderate climate areas. Although there is greater uncertainty associated with the impacts of climate change on drought periodicity than with shifts in mean conditions, our results show a greater potential for droughts to negatively impact species’ resilience to such changes.     

Using ecological niche modelling to infer past, present and future environmental suitability for Leiopelma hochstetteri, an endangered New Zealand native frog

Leiopelma hochstetteri is an endangered New Zealand frog now confined to isolated populations scattered across the North Island. A better understanding of its past, current and predicted future environmental suitability will contribute to its conservation which is in jeopardy due to human activities, feral predators, disease and climate change. Here we use ecological niche modelling with all known occurrence data (N = 1708) and six determinant environmental variables to elucidate current, pre-human and future environmental suitability of this species. Comparison among independent runs, subfossil records and a clamping method allow validation of models. Many areas identified as currently suitable do not host any known populations. This apparent discrepancy could be explained by several non exclusive hypotheses: the areas have not been adequately surveyed and undiscovered populations still remain, the model is over simplistic; the species’ sensitivity to fragmentation and small population size; biotic interactions; historical events. An additional outcome is that apparently suitable, but frog-less areas could be targeted for future translocations. Surprisingly, pre-human conditions do not differ markedly highlighting the possibility that the range of the species was broadly fragmented before human arrival. Nevertheless, some populations, particularly on the west of the North Island may have disappeared as a result of human mediated habitat modification. Future conditions are marked with higher temperatures, which are predicted to be favourable to the species. However, such virtual gain in suitable range will probably not benefit the species given the highly fragmented nature of existing habitat and the low dispersal ability of this species.     

空间生态位法在小流域森林资源评价中的应用

利用空间生态位的原理与方法,对小流域森林资源各树种(组)的空间生态宽度进行定量测定,并通过测定结果对流域中森林资源的空间行为与空间决策等问题进行分析与探讨,这对小流域生态治理和修复具有现实意义。     

淮北棉田害虫与捕食性天敌群落动态变化研究

对淮北棉田害虫和捕食性天敌群落动态变化进行了研究。田间系统调查共发现害虫35种,捕食性天敌24种;害虫优势种为棉蚜、烟粉虱、棉叶螨、棉盲蝽;捕食性天敌优势种主要为四点亮腹蛛、龟纹瓢虫、T-纹豹蛛、草间小黑蛛、八斑球腹蛛、华姬猎蝽、小花蝽、青翅隐翅虫。该区棉田害虫与捕食性天敌在棉株上的分布特点为:四点亮腹蛛、T-纹豹蛛、草间小黑蛛、八斑球腹蛛、小花蝽、青翅隐翅虫为下部>中部>上部;烟粉虱、棉盲蝽为上部>中部>下部;华姬猎蝽7月30日前为上部>下部>中部,8月9日后为下部>上部>中部;棉蚜在6月20日前为上部>下部>中部,在6月30日后为下部>上部>中部;棉叶螨前期主要分布在下部,后期向上转移;龟纹瓢虫在7月10日前为上部>中部>下部,7月20日之后为下部>上部>中部。群落均匀度在棉花生长发育前期较低,中期逐渐上升,后期又逐渐下降;集中度的变化趋势与均匀度相反;多样性在棉花生育中期最高。以物种为单位和以功能团为单位的群落多样性指数和均匀度指数呈高度正相关,相关系数(r)为0.9904。     

龙洞河流域马尾松群落结构及改造技术的研究

对龙洞河流域马尾松群落结构研究结果表明 ,龙洞河流域马尾松群落结构简单且物种多样性低 ,病虫害严重 ,生产力低下。并提出马尾松群落改造的原则、措施和模式     

“Mugnoli”: a Neglected Race of <Emphasis Type="Italic">Brassica oleracea</Emphasis> L. from Salento (Italy)

“Mugnoli”, a neglected race of Brassica oleracea L., is described from Southern Italy (Salento, Apulia). In this race, the young inflorescences together with a few leaves are harvested for use as a cooking vegetable. “Mugnoli” might be considered as an early step in the evolution of broccoli (B. oleracea L. var. italica Plenck).