昆明动物园野生小白鹭营巢高度选择与营巢材料研究

对昆明动物园内干香柏树上营巢的野生小白鹭进行研究,测算其最低适宜营巢枝干和实际最低营巢枝干占树高的百分比,并检测两者的差异显著性.结果表明,实际营巢高度与适宜营巢高度占树高百分比存在显著差异,可能因为亲鸟为避免来自地面的干扰,选择离地较高的位置繁育后代.通过分析坠落鸟巢的构成材料,发现其由268根植物枝条构成,其中91...     

高山红景天的繁殖生态学研究 Ⅰ生态因子与植物学、物候学特性分析

本研究对生长在新疆天山１号冰川观测站附近的高山红景天，从生境土壤的理化性质、气象因子等方面进行了观测与统计，并对其植物学及物候学特性进行了较详细的观察，结果表明：高山红景天植株的形态特征、生长发育节律与其特殊的生态环境是相适应的。     

Salt marshes – present functioning and future change

Salt marshes are no longer viewed as intertidal wastelands of little value to anyone. They are now widely recognised as playing a major role in coastal defence, in wildlife conservation on the coast and as a key source of organic material and nutrients vitally important for a wide range of marine communities. This appreciation of the importance of salt marshes has been brought even more sharply into focus because of the threats posed by predicted rise in sea level as a result of global climatic change. Three decades ago the possibilities of exchanges of organic matter between salt marshes and the sea were already being recognised in certain areas but it is only in the past five years or so that this process has been studied in a wide range of different areas. Detailed studies have been made into the way that salt marsh fluxes change with the development of increasingly mature and, therefore, increasingly complex salt marsh communities. As well as being sources and sinks of mineral nutrients and organic matter, salt marshes can also function as a sink for pollutants that would otherwise be damaging to the environment. Salt marshes also act as a sink for sediment within coastal ecosystems. Through their various functions they can be seen to be acting as dynamic living filters for various ecologically important materials. With increasing threats to the survival of salt marshes as a result of man's activities in the coastal zone being augmented by the threats from predicted sea level rise, a new approach to salt marsh conservation has come to the fore and that is the actual creation of new salt marshes. For this process to be fully effective we have to make full use of our increased understanding of salt marsh structure and function. Following a review of the current state of the art in the field of salt marsh research, an assessment is made of specific future research needs. Despite the greatly increased effort which has been directed to salt marsh research over the past few years we still have to recognise that resources are limited and, therefore, critical evaluations of the various options regarding the direction of our future efforts need to be made.     

Population isolation exacerbates conservation genetic concerns in the endangered Amargosa vole, Microtus californicus scirpensis

The ability of a taxon to maintain adaptive flexibility in a stochastic environment is a function of the genetic diversity within the population. In small, fragmented populations, genetic variation can become depleted more quickly than in larger, more contiguous populations. Characterizing the patterns of genetic variation and differentiation associated with these processes is an important step in establishing conservation priorities. The Amargosa vole, Microtus californicus scirpensis, is an endangered rodent persisting in the small, fragmented marsh complex surrounding the Amargosa River near Death Valley, California. This naturally patchy system has existed since the end of the Pleistocene (approximately 10,000 y.b.p.), however, fragmentation has been exacerbated by recent anthropogenic changes. For this study, I used five nuclear microsatellite loci and the cytochrome-b region of the mitochondrial genome to quantify levels of genetic variation, population substructure, and patterns of gene flow in M.c. scirpensis. These data were compared to a broadly distributed subspecies, Microtus californicus sanctidiegi. Overall levels of nuclear genetic variation were significantly lower in M.c. scirpensis, whether measured in terms of diversity or heterozygosity, compared to more broadly distributed conspecifics. Moreover, only two haplotypes were recovered from the mitochondrial data with over 90% of the observed haplotypes being identical. Despite low genetic diversity, significant genetic subdivision among M.c. scirpensis populations was detected using both pairwise F_ST and Bayesian clustering methods. Furthermore, isolation by distance analyses reveal that an important landscape feature, ephemeral tributaries, is critical for dispersal among population clusters. Recommendations for conservation management are presented.     

Why conservation reserves should not always be concentrated in riparian areas: A study of ground-dwelling beetles in wet eucalypt forest

Reserve corridors in production forestry landscapes are frequently concentrated in riparian areas. This study describes the numerical response of ground-dwelling beetles to increasing distance from streams, with the aim of evaluating the effectiveness of such a bias in reserve allocation. Patterns in abundance and diversity of epigaeic beetles were quantified at four first order streams in wet eucalypt forest in Tasmania, Australia. The depth and pattern of beetles’ riparian response varied between streams. Commonly trapped beetles were less abundant near to three of the four streams, and the numerical response model differed in each case. Species richness of common beetles was also lower near one of the streams. Pooled abundance and richness of rare species did not vary in response to the riparian-upslope transition. No riparian or upslope specialist species were identified among the most commonly collected species. Compared to upslope habitat, the riparian-upslope transition encompassed greater variability in species composition without actually increasing overall richness. The study findings demonstrate the need for ecosystem-specific data to optimize reserve placement, since the results were not predicted from general vegetation patterns, ecological theory, or the widely held assumption that riparian areas support greater abundance and diversity of organisms than adjacent upslope areas. Reserves encompassing more upslope habitat are recommended to complement those located in riparian areas.