Applied research of landscape ecology in desertification monitoring and assessment

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土地生态安全资源型关键地段识别——以长江三角洲无锡市为例

资源型关键地段对于维护和控制区域土地生态系统安全具有关键性作用。通过构建一套资源型关键地段识别的指标体系,在以次一级行政区为基本识别单元的基础上,识别出行政单元内地类斑块尺度的资源型关键地段。将无锡市划分为3级6类地段:关键地段、关键地段保护区、一般地段、干扰地段、干扰区以及交汇区,分别占全市总面积的19.70%、12.03%、39.62%、16.36%、12.28%和6.35%。关键地段斑块面积偏小、破碎化程度明显,空间分布不均匀,宜兴市境内关键地段占全市总量的85.26%;干扰地段斑块面积较大,空间分布不均,但相对集中,从面积和强度来看城区都较明显。干扰地段的形成受城镇空间发展影响明显;次一级行政区交汇区空间分布特征与形成原因不完全一致,空间分布也不均。城区50.48%、江阴40.91%、宜兴33.63%的关键地段保护区有被进一步破坏的可能。     

水资源生态足迹消费账户及其计算模型——以西安市为例

依据目前对水资源功能和水资源生态足迹理论的认识,把水污染消费纳入水资源消费账户,建立水资源生态足迹框架体系及其计算模型.应用模型对西安市2001-2007年的水资源生态足迹进行计算,并采用规模、结构和比较方法对计算结果进行分析.结果表明,西安市对废水污染较酸雨污染的治理力度大;废水污染、农业用水和酸雨污染在水资源生态足迹中所占比例较大,是各年的主要贡献者,而对水资源生态足迹整体下降量贡献最多的是废水污染(0.548 9 hm~2/人)和农业用水(0.031 9 hm~2/人);除个别年份外,水产品消费所占比例整体呈增大态势,生活用水、生产用水和其他用水所占比例变化较小.针对分析结果,提出了支持西安市可持续发展的水资源对策,包括调整水资源管理重点,拓宽和加大废水治理范围和深度,严格执行节能减排政策以及提高工农业用水效率等.     

城市植物叶面尘粒径和几种重金属(Cu、Zn、Cr、Cd、Pb、Ni)的分布特征

为研究城市植物叶面尘粒径及重金属元素(Cu、Zn、Cr、Cd、Pb、Ni)的分布规律和污染特征,以西安市不同功能区大叶女贞(Ligus-trum lucidum)和小叶女贞(Ligustrum quihoui)叶面尘为研究对象,用激光粒度分析仪测定叶面尘的粒径分布,用原子吸收分光光度计测定叶面尘重金属质量比,并探讨了叶面尘重金属的可能来源。结果表明,大叶女贞和小叶女贞叶面尘粒径小于50μm。前者叶面尘粒径累积曲线呈双峰分布,平均粒径和粒径峰值从大到小为相对清洁区、工业区、居住文教区、交通枢纽区、商业区;后者呈单峰分布,平均粒径和粒径峰值由大到小为工业区、居住文教区、交通枢纽区、商业区和相对清洁区。不同功能区叶面尘中Cu、Zn、Cr、Cd、Pb、Ni有明显的富集,其质量比分别为(325.5±72.6)mg/kg、(3 965.6±1 112.9)mg/kg、(349.2±149.3)mg/kg、(35.3±6.8)mg/kg、(1 182.0±355.1)mg/kg、(324.1±129.5)mg/kg,为陕西省土壤背景值的7.9～20.8、29.7～77.9、2.6～11.1、262.8～489.4、26.4～71.8和6.9～18.9倍。不同功能区2物种叶面尘各重金属质量比差异显著(p<0.001),物种间差异不显著(p>0.05)。叶面尘中Zn、Pb、Ni、Cr的质量比以工业区最高,Cu、Cd以交通枢纽区最高,其次为商业区,居住文教区和相对清洁区负荷最低。研究认为,叶面降尘中的重金属可能来自外源输入。     

Changes in vegetation persistence across global savanna landscapes, 1982–2010

We present a global analysis of the changing face of vegetation persistence in savanna ecosystems by boreal seasons. We utilized nearly 30 years of monthly normalized difference vegetation index data in an innovative time-series approach and developed associated statistical significance tests, making the application of continuous vegetation metrics both more rigorous and more useful to research. We found that 8,000,000–11,000,000 km² of savanna have experienced significant vegetation decline during each season, while 20,000,000–23,000,000 km² have experienced an increase in vegetation persistence during each season, relative to the baseline period (1982–1985). In addition, with the exception of the March–April–May season, which is mixed, the pattern of significant vegetation persistence in the Northern Hemisphere is almost exclusively positive, while it is negative in the Southern Hemisphere. This finding highlights the increasing vulnerability of the Southern Hemisphere savanna landscapes; either resulting from changing precipitation regimes (e.g., southern Africa) or agricultural pressures and conversions (e.g., South America).     

Assessing ecological correlates of marine bird declines to inform marine conservation

Identifying drivers of ecosystem change in large marine ecosystems is central for their effective management and conservation. This is a sizable challenge, particularly in ecosystems transcending international borders, where monitoring and conservation of long‐range migratory species and their habitats are logistically and financially problematic. Here, using tools borrowed from epidemiology, we elucidated common drivers underlying species declines within a marine ecosystem, much in the way epidemiological analyses evaluate risk factors for negative health outcomes to better inform decisions. Thus, we identified ecological traits and dietary specializations associated with species declines in a community of marine predators that could be reflective of ecosystem change. To do so, we integrated count data from winter surveys collected in long‐term marine bird monitoring programs conducted throughout the Salish Sea—a transboundary large marine ecosystem in North America's Pacific Northwest. We found that decadal declines in winter counts were most prevalent among pursuit divers such as alcids (Alcidae) and grebes (Podicipedidae) that have specialized diets based on forage fish, and that wide‐ranging species without local breeding colonies were more prone to these declines. Although a combination of factors is most likely driving declines of diving forage fish specialists, we propose that changes in the availability of low‐trophic prey may be forcing wintering range shifts of diving birds in the Salish Sea. Such a synthesis of long‐term trends in a marine predator community not only provides unique insights into the types of species that are at risk of extirpation and why, but may also inform proactive conservation measures to counteract threats—information that is paramount for species‐specific and ecosystem‐wide conservation. Evaluación de las Correlaciones Ecológicas de las Declinaciones de Aves Marinas para Informar a la Conservación Marina     

Evaluating mortality rates with a novel integrated framework for nonmonogamous species

The conservation of wildlife requires management based on quantitative evidence, and especially for large carnivores, unraveling cause‐specific mortalities and understanding their impact on population dynamics is crucial. Acquiring this knowledge is challenging because it is difficult to obtain robust long‐term data sets on endangered populations and, usually, data are collected through diverse sampling strategies. Integrated population models (IPMs) offer a way to integrate data generated through different processes. However, IPMs are female‐based models that cannot account for mate availability, and this feature limits their applicability to monogamous species only. We extended classical IPMs to a two‐sex framework that allows investigation of population dynamics and quantification of cause‐specific mortality rates in nonmonogamous species. We illustrated our approach by simultaneously modeling different types of data from a reintroduced, unhunted brown bear (Ursus arctos) population living in an area with a dense human population. In a population mainly driven by adult survival, we estimated that on average 11% of cubs and 61% of adults died from human‐related causes. Although the population is currently not at risk, adult survival and thus population dynamics are driven by anthropogenic mortality. Given the recent increase of human‐bear conflicts in the area, removal of individuals for management purposes and through poaching may increase, reversing the positive population growth rate. Our approach can be generalized to other species affected by cause‐specific mortality and will be useful to inform conservation decisions for other nonmonogamous species, such as most large carnivores, for which data are scarce and diverse and thus data integration is highly desirable.     

Using a common commensal bacterium in endangered Takahe as a model to explore pathogen dynamics in isolated wildlife populations

Predicting and preventing outbreaks of infectious disease in endangered wildlife is problematic without an understanding of the biotic and abiotic factors that influence pathogen transmission and the genetic variation of microorganisms within and between these highly modified host communities. We used a common commensal bacterium, Campylobacter spp., in endangered Takahe (Porphyrio hochstetteri) populations to develop a model with which to study pathogen dynamics in isolated wildlife populations connected through ongoing translocations. Takahe are endemic to New Zealand, where their total population is approximately 230 individuals. Takahe were translocated from a single remnant wild population to multiple offshore and mainland reserves. Several fragmented subpopulations are maintained and connected through regular translocations. We tested 118 Takahe from 8 locations for fecal Campylobacter spp. via culture and DNA extraction and used PCR for species assignment. Factors relating to population connectivity and host life history were explored using multivariate analytical methods to determine associations between host variables and bacterial prevalence. The apparent prevalence of Campylobacter spp. in Takahe was 99%, one of the highest reported in avian populations. Variation in prevalence was evident among Campylobacter species identified. C. sp. nova 1 (90%) colonized the majority of Takahe tested. Prevalence of C. jejuni (38%) and C. coli (24%) was different between Takahe subpopulations, and this difference was associated with factors related to population management, captivity, rearing environment, and the presence of agricultural practices in the location in which birds were sampled. Modeling results of Campylobacter spp. in Takahe metapopulations suggest that anthropogenic management of endangered species within altered environments may have unforeseen effects on microbial exposure, carriage, and disease risk. Translocation of wildlife between locations could have unpredictable consequences including the spread of novel microbes between isolated populations.     

Use of ecoacoustics to determine biodiversity patterns across ecological gradients

The variety of local animal sounds characterizes a landscape. We used ecoacoustics to noninvasively assess the species richness of various biotopes typical of an ecofriendly forest plantation with diverse ecological gradients and both nonnative and indigenous vegetation. The reference area was an adjacent large World Heritage Site protected area (PA). All sites were in a global biodiversity hotspot. Our results showed how taxa segregated into various biotopes. We identified 65 singing species, including birds, frogs, crickets, and katydids. Large, natural, protected grassland sites in the PA had the highest mean acoustic diversity (14.1 species/site). Areas covered in nonnative timber or grass species were devoid of acoustic species. Sites grazed by native and domestic megaherbivores were fairly rich (5.1) in acoustic species but none were unique to this habitat type, where acoustic diversity was greater than in intensively managed grassland sites (0.04). Natural vegetation patches inside the plantation mosaic supported high mean acoustic diversity (indigenous forests 7.6, grasslands 8.0, wetlands 9.1), which increased as plant heterogeneity and patch size increased. Indigenous forest patches within the plantation mosaic contained a highly characteristic acoustic species assemblage, emphasizing their complementary contribution to local biodiversity. Overall, acoustic signals determined spatial biodiversity patterns and can be a useful tool for guiding conservation.     

沈阳辉山水库污染源调查研究

对沈阳市重要水生态湿地辉山水库的工业、生活、农业、地面径流及明渠污染源进行了详细的调查。结果显示,污染源最大分担率分别是：COD。是明渠输入源,为95．34％;总氮、总磷和固废入河量是生活源,分别为99．73％,99．20％和95．87％;污水是工业源,为91．74％;粪尿是农业源,为94．79％。