南泥湾湿地退化与管理对土壤动物多样性的影响

为查明南泥湾湿地生态系统退化对土壤动物群落的影响,于2016年3、6、9和11月分别对南泥湾不同退化阶段湿地的土壤动物群落进行调查。共捕获土壤动物3 285头,隶属4门10纲26目。优势类群为蜱螨目(Acarina)、小杆目(Rhabditida)和弹尾纲(Collembola)。随着退化程度加重,土壤动物群落密度和类群数下降,重度退化和已垦湿地土壤动物密度和多样性指数均极显著低于其他退化阶段(P0. 01)。各样地相似性系数差异分析表明,退化、开垦和退耕均对南泥湾湿地土壤动物群落组成类群和优势类群个体数有较大影响。土壤动物群落密度和多样性的季节动态在不同退化阶段间存在差异,退化会影响土壤动物群落季节变化稳定性。土壤动物优势类群时空分布受退化程度的影响,且不同优势类群受影响程度存在差异。相关分析结果表明土壤动物密度与土壤有机质和全氮含量呈正相关,与pH呈负相关。研究结果表明南泥湾湿地退化会影响土壤动物群落组成和多样性的空间分布和季节动态,而人为开垦活动会降低土壤动物密度和多样性,退耕还湿措施可以使湿地土壤动物密度表现出明显季节变化规律。     

不同灌溉模式对广西蔗田大型土壤动物群落结构的影响

为了探讨不同灌溉模式对大型土壤动物群落结构的影响,在广西崇左市江州区糖料蔗节水灌溉试验区设置地埋滴灌、地表滴灌、管灌、喷灌、微喷5种灌溉处理以及无灌溉空白对照共6个样地,于2015年5—11月对大型土壤动物群落及土壤理化性质进行调查。共捕获大型土壤动物1 180只,隶属于2门10纲18目,优势类群为膜翅目(蚁科),占总数的71.44%;常见类群为蜘蛛目、等翅目(白蚁科)、革翅目、直翅目、鞘翅目、蜚蠊目、半翅目和等足目。不同灌溉模式各样地大型土壤动物类群数差异不显著。灌溉处理样地大型土壤动物密度、ShannonWiener多样性指数(H)、Pielou均匀度指数(E)和Margalef丰富度指数(D)均优于无灌溉样地,Simpson优势度指数(C)则相反,并且地埋滴灌、喷灌样地与无灌溉样地间上述指标均差异显著。不同灌溉模式对蔗田土壤理化性质产生显著影响,地埋滴灌、地表滴灌、管灌、喷灌和微喷样地土壤含水率、有机质含量、速效氮含量、速效磷含量及速效钾含量均高于无灌溉样地,且地埋滴灌与喷灌样地上述指标值较高。节水灌溉增强了土壤的储水能力,提高了土壤的营养条件,改善了蔗田土壤的微环境。大型土壤动物群落结构在不同灌溉模式下变化显著,主要表现在大型土壤动物密度与多样性增加,地埋滴灌和喷灌方式样地表现尤为突出。     

半干旱区草地生境中大型土壤动物群落季节动态

选择科尔沁沙地封育草地为研究对象,通过调查大型土壤动物个体数和类群数的季节变化特征及其与气候因子间的关系,分析大型土壤动物群落结构的季节变化规律。结果表明,伴随着气候因子(降雨量和气温)的季节变化,土壤含水量表现为春季>秋季>夏季,而土壤温度表现为夏季>春季>秋季。土壤温湿度的季节性变化显著影响了大型土壤动物群落结构(P<0.05)。大型土壤动物类群数和个体数以及Shannon指数均表现为夏季显著高于秋季(P<0.05),春季居中;而均匀度指数则与此相反(P<0.05),表现为夏季<春季<秋季。随着季节更替,不同大型土壤动物类群对气候因子变化产生了不同的响应和适应性,不同季节表现出了不同的大型土壤动物类群及其个体数分布,而且在夏季表现出较高的大型土壤动物多样性。     

汶川大地震后川西亚高山针叶林土壤动物群落变迁

对川西亚高山针叶林土壤动物群落汶川大地震前后的结构特征进行对比研究,旨在通过土壤动物对地震的响应了解地震对川西亚高山针叶林生态系统功能及过程的影响.结果显示,地震后大型土壤动物类群数、个体密度、DG指数均有小幅增长,但无显著差异;中小型土壤动物类群中,湿生土壤动物线虫的个体密度有一定增加,而干生土壤动物蜱螨目、弹尾目的个体密度有一定减少,但均无显著差异;土壤原生动物由7 083个/g鲜土降至625个/g鲜土,有极显著差异(P0.01).研究表明,受地震影响的林地内,不同体型的土壤动物响应不同,其中,大型土壤动物多样性有所增加,主要与微域生境趋于复杂化有关,而小型和微型土壤动物多样性有所减少,则与地下水位的变化有关.图1表2参16     

铜陵市铜尾矿土壤动物群落生态研究

对安徽省铜陵市铜尾矿地6种生境中土壤动物群落进行野外调查和室内分析，研究不同弃置堆放时间的铜尾矿地土壤的动物群落结构及其与尾矿基质理化性质、植被状况等生境条件之间的关系。结果表明，尾矿堆放时间、区位地貌和植被状况的不同，尾矿基质的理化性质发生变化，导致土壤动物的种类组成和数量分布具有明显差异。土壤动物在土体中的表聚性强，绝大部分集中分布于A层(0～5cm)；土壤的物理性质越稳定，土壤动物越丰富；土壤肥力越高，土壤动物越丰富多样。即尾矿地土壤的生境条件越优越，土壤动物群落的物种丰富度越大，个体数量分布越多，群落多样性越高。这些研究结论为尾矿区的生态修复和可持续利用提供了参考依据。     

放牧干扰后自然恢复沙质草地大型土壤动物功能群变化特征

通过调查科尔沁沙质退化草地不同强度放牧干扰（重度放牧,HGR;适度放牧,MGR）后自然恢复草地中大型土壤动物群落特征,分析了放牧干扰对大型土壤动物功能群的长期影响。结果共获得大型土壤动物1门2纲8目32个类群,优势类群为象甲科（鞘翅目）和蚁科（膜翅目）2类,共占捕获量的41．54％。大型土壤动物功能群包括植食性、肉食性和杂食性3类,分别具有16、15和1个类群,其个体数分别占总捕获数的64．08％、32．39％和3．52％。HGR有23个动物类群,分属于3个功能群;MGR有19个类群,但只有2个功能群（无杂食性）。HGR大型土壤动物个体数、类群数和多样性指数均略高于MGR,但HGR和MGR间无显著差异性（P〉0．05）。植食性和肉食性土壤动物个体数占总个体数比例HGR均略低于MGR,但植食性动物和肉食性动物个体数间的比例较稳定。与中度放牧干扰产生的影响相比,重度放牧干扰对大型土壤动物群落（包括功能群特征）产生的长期影响更为明显。重度放牧后沙质草地自然恢复过程中大型土壤动物群落的营养结构变得更为复杂,但12年恢复时间对大型土壤动物群落结构恢复的影响有限。     

左家自然保护区采伐迹地土壤动物群落特征

林地采伐后形成采伐迹地,其植被处于逐渐恢复阶段,改变了原有地上植物群落组成及土壤的生态环境.于2011年4月和7月研究了吉林左家自然保护区采伐13-14年迹地和未被采伐的相应生境的土壤动物群落结构,以期为森林生态系统恢复提供土壤动物学依据.采样生境分别是:蒙古栎+黑桦林采伐迹地,人工落叶松林采伐迹地,蒙古栎+黑桦林和人工落叶松林.结果显示:蒙古栎+黑桦林采伐迹地大型土壤动物个体密度为251.5只/m2,类群数22类,多样性指数为2.34,显著低于未经采伐蒙古栎+黑桦林的个体密度(309.5只/m2)、类群数(30类)、多样性指数(3.13);中小型土壤动物个体密度为0.97×104只/m2,类群数20类,多样性指数1.98,均低于未经采伐蒙古栎+黑桦林的个体密度(2.12×104只/m2)、类群数(22类)、多样性指数(2.05).人工落叶松林采伐迹地则相反.土壤动物群落与土壤有机质、全氮(P0.05)和pH(P0.05)有明显相关性,而与土壤全磷(P0.05)和含水率(P0.05)相关性不明显.总之,采伐在一定程度上改变了土壤动物的群落组结构,但由于采伐前林型不同使得采伐后植被恢复过程中土壤动物群落的变化也存在差异.     

模拟氮沉降对苗圃地土壤动物群落的影响

通过人工喷施氮H4NO3建立了一个模拟氮沉降增加梯度系列,在近18个月的试验处理期间,研究了2003年7月、10月和2004年2月、5月这几个不同季度苗圃试验样地土壤动物群落对氮沉降增加的响应。实验分为5个处理组:对照、低氮、中氮、高氮和倍高氮,分别接受0、5、10、15、30g/(m2·a)的氮沉降量。土壤细菌和真菌的数量总体上随氮处理的加强而持续显著地增长,土壤有机氮含量也持续升高,土壤酸度则不断下降。采样期对土壤动物的个体数量、类群丰度和多样性存在显著的影响,总的来说,土壤动物群落随试验处理期加长而持续增长。土壤动物群落具有显著的垂直分异特征,土壤I层土壤动物个体数量、类群丰度和多样性显著高于II和III层。氮沉降增加对土壤动物群落有明显的影响,表现为施氮处理明显有利于土壤动物群落的发展,但也具有明显的阀值效应。与对照样地相比,各施氮处理样地土壤动物群落水平整体为高,而且随试验处理时间的增加这种差异有加大的趋势;氮沉降增加处理与取样期之间存在显著的交互作用,除了2月取样,中氮处理土壤动物群落水平都处于最高水平,而对照处理一般处于最低水平,这种趋势在最后一次取样中最为明显;氮沉降处理与土壤动物的垂直分布之间也有明显的交互作用:在土壤I层,从对照至倍高氮处理,土壤动物群     

大兴安岭火烧迹地土壤动物的群落多样行

以大兴安岭地区不同年份火烧迹地土壤动物为研究对象,对火烧后不同恢复时间土壤动物群落多样性及相关指数的变化进行分析.结果表明,大型土壤动物的个体数、DIC指数、丰富度指数及优势度指数变化趋势均表现为火烧恢复初期迅速增加,然后缓慢增加并逐渐接近对比样地值;如果不考虑8 a迹地数据极大值的影响,中小型土壤动物的个体数、DIC指数、丰富度指数及优势度指数也大致呈现火烧恢复初期迅速增加,然后缓慢增长的趋势;在垂直方向上,大型土壤动物DIC指数、个体数及丰富度指数在0～5 cm最大,向上、向下减少,而中小型土壤动物的各项指数都是凋落物层最大,向下迅速减小;相关分析表明,大型和中小型土壤动物的个体数和丰富度指数与DIC指数都具有极高的相关性;群落相似性分析显示,各火烧迹地间土壤动物群落具有较高的相似性.图1表3参26     

长白山地不同地貌类型农田生态系统土壤动物群落特征及季节动态

土壤动物对改善农田生态系统土壤生态环境、修复退化的生态功能起着不可替代的作用.分别于2015年的春季、夏季和秋季对长白山地玄武岩台地、花岗岩低山区、花岗岩丘陵区玉米田的土壤动物进行研究.其中大型土壤动物的获取采用手捡法,中小型土壤动物采用Tullgren分离.结果表明:3次取样共获取土壤动物2 956只,计42类,隶属于3门7纲16目,甲螨亚目和等节跳虫科是各地貌类型共有的优势类群.各地貌类型土壤动物个体密度和类群数均为花岗岩低山区最低;玄武岩台地土壤动物个体密度夏季最高,花岗岩低山区和花岗岩丘陵区秋季最高.垂直分布上3个地貌类型土壤动物个体密度均具有表聚性,但花岗岩丘陵区表聚性不明显.土壤动物多样性表现为花岗岩丘陵区最高,花岗岩低山区最低;春季、夏季花岗岩丘陵区土壤动物多样性最高,秋季各地貌类型土壤动物多样性差异并不显著.本研究表明长白山地不同地貌类型农田生态系统土壤动物群落特征及季节动态存在显著差异.     

Rapid,recurring, structured survey versus bioblitz for generating biodiversity data and analysis with a multispecies abundance model

A bioblitz inexpensively and quickly generates biodiversity data, but bioblitzes are often conducted with haphazard, unreplicated sampling. Results tend to be taxonomically, geographically, or temporally biased, lack metadata, and consist of lists of observed taxa that do not enable further analyses or correction for imperfect detection. A rapid, recurring, structured survey (RRSS) uses a structured sampling design and temporal and spatial replication to survey randomly selected sites on a conservation property. We participated in a loosely structured bioblitz and a subsequent RRSS at Big Canoe Creek Nature Preserve in Springville (St. Clair County), Alabama (USA) to compare observed richness derived from the 2 survey approaches. The RRSS data structure enabled us to fit models that accounted for imperfect detection to estimate abundances, occupancy probabilities, and habitat associations. The loosely structured bioblitz data could not be used in such models. We present a new integrated multispecies abundance model that we applied to avian RRSS data. Our model extension enables estimation for the community, employs data augmentation to estimate the number of undetected species, and incorporates covariates. The RRSS generated a more comprehensive and less biased list of observed taxonomic richness than the loosely structured bioblitz (e.g., 73 vs. 45 bird species and 104 vs. 63 insect families from the RRSS vs. loosely structured bioblitz, respectively). Models fit to the RRSS data identified seasonal patterns in avian community composition and allowed for estimation of habitat–occupancy relationships for insect taxa. The RRSS protocol has potential for broad transferability as a standardized, quick, and inexpensive way to inventory biodiversity and estimate ecological parameters while providing an outreach opportunity.     

Compliance with and ecosystem function of biodiversity offsets in North American and European freshwaters

Land-use change via human development is a major driver of biodiversity loss. To reduce these impacts, billions of dollars are spent on biodiversity offsets. However, studies evaluating offset project effectiveness that examine components such as the overall compliance and function of projects remain rare. We reviewed 577 offsetting projects in freshwater ecosystems that included the metrics project size, type of aquatic system (e.g., wetland and creek), offsetting measure (e.g., enhancement, restoration, and creation), and an assessment of the projects’ compliance and functional success. Project information was obtained from scientific and government databases and gray literature. Despite considerable investment in offsetting projects, crucial problems persisted. Although compliance and function were related to each other, a high level of compliance did not guarantee a high degree of function. However, large projects relative to area had better function than small projects. Function improved when projects targeted productivity or specific ecosystem features and when multiple complementary management targets were in place. Restorative measures were more likely to achieve targets than creating entirely new ecosystems. Altogether the relationships we found highlight specific ecological processes that may help improve offsetting outcomes.     

A palaeo-hydrogeological model for arsenic contamination in southern and south-east Asia

An argument is presented in which areas of natural arsenic contamination of modern groundwaters throughout Asia have a common origin. Arsenic originally accumulated in oceanic ferro-manganoan sediments of the eastern Palaeo-Tethys. This was further concentrated through oceanic crustal extinction in what later became the south-east Chinese accreted mineralised terrain. Proto-Himalayan uplift of this area created the palaeo-drainage systems of the Ganges – Brahmaputra, Irrawaddy, Mekong, and Red Rivers, with consequent headwater erosion of arsenic-rich sediments. Their downstream deposition as immature and easily redistributed Neogene sandstones, silts, and iron-rich clays has created secondary and tertiary reservoirs of adsorbed and authigenic arsenic, from which the current arsenic-rich groundwaters have evolved. Considering river basins within the above palaeo-hydrogeological framework provides a basis for assessing the risk of arsenic in groundwater basins of south and south-eastern Asia.     

Cost‐effective conservation of an endangered frog under uncertainty

How should managers choose among conservation options when resources are scarce and there is uncertainty regarding the effectiveness of actions? Well‐developed tools exist for prioritizing areas for one‐time and binary actions (e.g., protect vs. not protect), but methods for prioritizing incremental or ongoing actions (such as habitat creation and maintenance) remain uncommon. We devised an approach that combines metapopulation viability and cost‐effectiveness analyses to select among alternative conservation actions while accounting for uncertainty. In our study, cost‐effectiveness is the ratio between the benefit of an action and its economic cost, where benefit is the change in metapopulation viability. We applied the approach to the case of the endangered growling grass frog (Litoria raniformis), which is threatened by urban development. We extended a Bayesian model to predict metapopulation viability under 9 urbanization and management scenarios and incorporated the full probability distribution of possible outcomes for each scenario into the cost‐effectiveness analysis. This allowed us to discern between cost‐effective alternatives that were robust to uncertainty and those with a relatively high risk of failure. We found a relatively high risk of extinction following urbanization if the only action was reservation of core habitat; habitat creation actions performed better than enhancement actions; and cost‐effectiveness ranking changed depending on the consideration of uncertainty. Our results suggest that creation and maintenance of wetlands dedicated to L. raniformis is the only cost‐effective action likely to result in a sufficiently low risk of extinction. To our knowledge we are the first study to use Bayesian metapopulation viability analysis to explicitly incorporate parametric and demographic uncertainty into a cost‐effective evaluation of conservation actions. The approach offers guidance to decision makers aiming to achieve cost‐effective conservation under uncertainty.     

Threats to intact tropical peatlands and opportunities for their conservation

Large, intact areas of tropical peatland are highly threatened at a global scale by the expansion of commercial agriculture and other forms of economic development. Conserving peatlands on a landscape scale, with their hydrology intact, is of international conservation importance to preserve their distinctive biodiversity and ecosystem services and maintain their resilience to future environmental change. We explored threats to and opportunities for conserving remaining intact tropical peatlands; thus, we excluded peatlands of Indonesia and Malaysia, where extensive deforestation, drainage, and conversion to plantations means conservation in this region can protect only small fragments of the original ecosystem. We focused on a case study, the Pastaza‐Marañón Foreland Basin (PMFB) in Peru, which is among the largest known intact tropical peatland landscapes in the world and is representative of peatland vulnerability. Maintenance of the hydrological conditions critical for carbon storage and ecosystem function of peatlands is, in the PMFB, primarily threatened by expansion of commercial agriculture linked to new transport infrastructure that is facilitating access to remote areas. There remain opportunities in the PMFB and elsewhere to develop alternative, more sustainable land‐use practices. Although some of the peatlands in the PMFB fall within existing legally protected areas, this protection does not include the most carbon‐dense (domed pole forest) areas. New carbon‐based conservation instruments (e.g., REDD+, Green Climate Fund), developing markets for sustainable peatland products, transferring land title to local communities, and expanding protected areas offer pathways to increased protection for intact tropical peatlands in Amazonia and elsewhere, such as those in New Guinea and Central Africa which remain, for the moment, broadly beyond the frontier of commercial development.     

Parasitic wasps orient to green leaf volatiles

Summary Undamaged plants emit low levels of green leaf volatiles (GLVs), while caterpillar-damaged and artificially damaged plants emit relatively higher levels of certain GLVs. Female braconid parasitoids,Microplitis croceipes, oriented to both damaged plants and to individual GLVs in no-choice tests in a wind tunnel, but seldom oriented to undamaged plants. Female ichneumonid parasitoids,Netelia heroica, also oriented to individual GLVs in a wind tunnel. Males of both wasp species failed to orient to the GLVs. These data show that leaf-feeding caterpillars can cause the release of GLVs, and that parasitic wasps can respond to these odors by flying upwind (chemoanemotactic response), which brings the wasps to their caterpillar hosts. This supports the hypothesis that plants communicate with members of the third trophic level,i.e., plants under herbivore attack emit chemical signals that guide natural enemies of herbivores to sites of plant damage. In this interaction, the GLVs serve as tritrophic plant-to-parasitoid synomones. That parasitoids from two different wasp families oriented to GLVs suggests that the response may be widespread among the Hymenoptera.Mention of a commercial or proprietary product does not constitute an endorsement by the U.S. Department of Agriculture     

Human Influence and Classical Biogeographic Predictors of Rare Species Occurrence

Biogeographic theory predicts that rare species occur more often in larger, less‐isolated habitat patches and suggests that patch size and connectivity are positive predictors of patch quality for conservation. However, in areas substantially modified by humans, rare species may be relegated to the most isolated patches. We used data from plant surveys of 81 meadow patches in the Georgia Basin of Canada and the United States to show that presence of threatened and endangered plants was positively predicted for patches that were isolated on small islands surrounded by ocean and for patches that were isolated by surrounding forest. Neither patch size nor connectivity were positive predictors of rare species occurrence. Thus, in our study area, human influence, presumably due to disturbance or introduction of competitive non‐native species, appears to have overwhelmed classical predictors of rare species distribution, such that greater patch isolation appeared to favor presence of rare species. We suggest conservation planners consider the potential advantages of protecting geographically isolated patches in human‐modified landscapes because such patches may represent the only habitats in which rare species are likely to persist. Influencia Humana y Predictores Biogeográficos Clásicos de la Ocurrencia de Especies Raras     

Seasonal dynamics of macro-algae in the South Lake of Tunis

The macro-algae communities observed in the south lake of Tunis are characterized by the predominance of nitrophilous algae which are in the order of biomass importance:Ulva, Cladophora andEnteromorpha. We have noted seasonal changes of alga distribution. The wind appears to be one of the most important factors influencing this distribution. The total biomass reaches a maximum in the spring. Rapid decomposition of the biomass leads to a severe ecological imbalance, resulting in crises of anoxia and fish death. A restoration project has already started. It aims at removal of contaminated muds and the introduction of a new circulation system. The main objectives of this work were to collect information on the distribution and biomass of the phytobenthic communities as a first step in the constitution of a database for further comparison.     

Patterns and biases of climate change threats in the IUCN Red List

International Union for Conservation of Nature (IUCN) Red List assessments rely on published data and expert inputs, and biases can be introduced where underlying definitions and concepts are ambiguous. Consideration of climate change threat is no exception, and recently numerous approaches to assessing the threat of climate change to species have been developed. We explored IUCN Red List assessments of amphibians and birds to determine whether species listed as threatened by climate change display distinct patterns in terms of habitat occupied and additional nonclimatic threats faced. We compared IUCN Red List data with a published data set of species’ biological and ecological traits believed to infer high vulnerability to climate change and determined whether distributions of climate change‐threatened species on the IUCN Red List concur with those of climate change‐threatened species identified with the trait‐based approach and whether species possessing these traits are more likely to have climate change listed as a threat on the IUCN Red List. Species in some ecosystems (e.g., grassland, shrubland) and subject to particular threats (e.g., invasive species) were more likely to have climate change as a listed threat. Geographical patterns of climate change‐threatened amphibians and birds on the IUCN Red List were incongruent with patterns of global species richness and patterns identified using trait‐based approaches. Certain traits were linked to increases or decreases in the likelihood of a species being threatened by climate change. Broad temperature tolerance of a species was consistently related to an increased likelihood of climate change threat, indicating counterintuitive relationships in IUCN assessments. To improve the robustness of species assessments of the vulnerability or extinction risk associated with climate change, we suggest IUCN adopt a more cohesive approach whereby specific traits highlighted by our results are considered in Red List assessments. To achieve this and to strengthen the climate change‐vulnerability assessments approach, it is necessary to identify and implement logical avenues for further research into traits that make species vulnerable to climate change (including population‐level threats).