Continental-scale interactions with temporary resources may explain the paradox of large populations of desert waterbirds in Australia

Arid Australia supports extraordinary numbers of waterbirds. We show that the solution to this seeming paradox lies in considering the availability of temporary wetland habitat in the context of the birds dispersal capability and fluctuations in the abundance of wetlands in time and space. For species with large dispersal capabilities, the Lake Eyre Basin of central Australia, amongst the driest regions on the continent, has the highest habitat availability for waterbirds. Analyses of landscape structure show that the wetlands of the Lake Eyre Basin are highly inter-connected and linked by broad pathways to wetter parts of south-eastern Australia. These analyses illustrate that organism traits and patch dynamics affect realised habitat availability and indicate that the processes that structure populations may operate at much larger spatial scales than those at which humans usually seek to manage the landscape.     

Changes to the landscape pattern of coastal North Carolina wetlands under the Clean Water Act, 1984–1992

Wetland management in the United States is organized through a permit process that requires a permit be filed with the U.S. Army Corps of Engineers prior to wetland alteration. A collection of these permits from 1984 through 1992 was analyzed in conjunction with classified Landsat Thematic Mapper data from 1984 and 1992 in order to quantify changes to wetland habitat in the study area in coastal North Carolina. The wetland management process in the U.S. focuses on a site-by-site review, possibly overlooking important changes to wetlands at the landscape-scale. These the two datasets were used to determine if wetland habitat loss was occurring at permit sites, but also to determine if landscape-scale wetland fragmentation and reorganization were occurring in the area surrounding each permit site under the wetland management process. The use of these two datasets attempted to span two scales: the site-specific scale often used in the management of wetlands, and the landscape-scale where effects of such management are evident. Important conclusions from the research include the following. First, while several sources imply that coastal wetlands are disproportionately protected as a result of the widespread recognition of their habitat value, estuarine wetlands were altered much more frequently in the study area than their inland counterparts. Second, despite federal level efforts that require compensatory mitigation when wetland habitat is lost, such mitigation was required in only three percent of permits, ensuring wetland loss. Third, correlation between estimates of wetland loss from the Permit Record and from the remotely sensed record was minimal, highlighting the problems inherent to wetland delineation and implying alterations to habitat not evidenced in the permit record. Finally, landscape-scale changes of loss, fragmentation and habitat reorganization have occurred in estuarine emergent wetland habitat in areas adjacent to several permit sites, implying unanticipated additional impacts to permitted actions. Wetland loss at the permit site occurred with additional fragmentation in 80 percent of the sites examined. The results highlight the lack of agreement between management and landscape-scale wetland structure, function and change, and imply the importance of examining the spatial context of permit sites in the permit review and evaluation procedure.     

Analysis of landscape patterns in coastal wetlands of Galveston Bay,Texas (USA)

High productivity and accessibility have made coastal wetlands attractive sites for human settlements. This study analyzed the patterns of wetland landscapes in Galveston Bay, Texas, USA. The first objective of the study was to describe the relationships between the fractal dimension of wetland boundaries and those factors which affect the wetland landscapes (e.g., land use, type of vegetation, size, location, and level of human disturbance). The second objective was to construct a historical database to contrast wetland areas which had experienced different levels of disturbance between 1956 and 1989. The fractal dimension, a measure of how much of the geographical space is filled by boundaries, was measured by the perimeter-area method. The fractal dimension of wetlands was significantly affected by land use, type of vegetation, size, and level of anthropogenic disturbance. In addition, increasing the size of buffers around roads did not significantly affect the fractal dimension of wetlands. Landscape indices, such as fractal dimension, dominance, and diversity, were used to characterize spatial heterogeneity in the historical database. Lake Stephenson, an area of low anthropogenic disturbance, experienced no changes in wetland composition and abundance over time. Anahuac, an area of medium disturbance, experienced changes in both wetland composition and abundance. Texas City, an area of high disturbance, experienced a change in wetland composition. These differences can be associated with the type and level of disturbance present; however, more evidence is needed to determine whether certain landscape patterns have stable, intrinsic properties which allow persistence in the face of disturbance. These results will be informative to resource managers determining how wetlands can be managed as natural resources and nature reserves.     

The use of wetlands (dambos) for micro-scale irrigation in Zimbabwe

Micro-scale irrigation on wetlands or dambos has been practised in Zimbabwe for over 100 years with, at present, an estimated 20,000 ha under cultivation in the communal areas. The results of recent research indicate that there is great potential for increasing the area and the intensity of such cultivation. The advantages of micro-scale irrigation are discussed and it is argued that this scale of irrigation should be considered when formulating policy and allocating resources for irrigation.Abbreviations Communal areas Areas in Zimbabwe historically reserved for blacks and distinguished from the commercial farming areas with better resources     

洞庭湖湿地杨树人工林对土壤理化性质的影响

近几十年来的杨树大面积种植引发了人们对洞庭湖湿地生态系统生态环境恶化的担忧。本研究以11龄与5龄杨树林为对象,以邻近的典型湿地植被南荻为对照,拟阐明杨树人工林对土壤理化性质的影响。结果表明,对土壤物理特性而言,杨树的种植加速了土壤水分的散失,对水分改变的趋势随林龄的增加而增大;杨树人工林改变了土壤粒径组成,致使粘粒与粉粒的降低、砂粒的增加,砂粒化趋势随林龄的增大而增强;对土壤化学特性而言,杨树人工林导致土壤中层(20-60 cm)电导率的降低,以及下层(60-100 cm)pH值的升高,对土壤全磷含量无明显影响,总体上降低了土壤全钾含量;引起土壤40-60 cm全氮含量的降低,降低趋势随林龄的增加而增大。此外,两种杨树林对土壤全碳的影响不同,低林龄能降低土壤全碳含量,而高林龄有利于碳的增加。可见,大规模种植杨树导致土壤特性的重要改变必将对湿地生态系统产生深远的影响。     

茂兰喀斯特森林湿地资源现状与保护建议

经调查,茂兰喀斯特森林湿地植物有369种,分属118科279属;脊椎动物124种,隶属5纲19目48科。通过对茂兰喀斯特森林湿地资源现状、潜在的威胁进行分析,提出了湿地保护建议,以期为森林湿地资源的保护提供参考。     

Linking vegetation patterns,wetlands conservation,and ecosystem services provision: From publication to application

1. Natural wetlands emerge as the best sites to preserve the diversity of aquatic and riparian vegetation; however, especially in the lowlands, pristine wetlands and aquatic ecosystems have almost completely disappeared through land reclamation and agricultural development. Actions are needed, therefore, to maintain and recreate a wide network of wetlands able to preserve adequate levels of vegetation diversity.
2. Focusing on a complex wetland system located in an overexploited plain, the article entitled ‘The importance of being natural in a human‐altered riverscape: Role of wetland type in supporting habitat heterogeneity and the functional diversity of vegetation’, published in 2016 in Aquatic Conservation: Marine and Freshwater Ecosystems (AQC) explored the role of wetland origin and hydrology as the main drivers of physical and vegetation functional diversity, following a hierarchical sampling approach.
3. The main results reinforced the key contribution of natural sites in maintaining vegetation diversity in heavily impaired riverine contexts, suggesting a direct effect of the interannual and seasonal dynamics of water‐level variations in the observed vegetation patterns.
4. The article offered an important contribution to our knowledge of vegetation patterns in wetlands, partly attributed to the innovative functional, hierarchical approach applied which is able to guarantee reliable data on the distribution patterns of physical heterogeneity and wetland vegetation.
5. The findings of the article have been applied and adopted in a series of technical handbooks designed, inter alia, to support the monitoring programmes of habitats of community interest or vegetation of relevance for aquatic biodiversity conservation. In addition, this article has helped to raise awareness of the essential roles played by wetlands in agricultural landscapes and has emphasized the need for a better synergy between the European Habitats Directive and the Water Framework Directive. Several ecological recovery projects have been funded in line with the results described in the AQC article.

     

Biodiversity value of agricultural drainage ditches: a comparative analysis of the aquatic invertebrate fauna of ditches and small lakes

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Drivers of biodiversity loss in freshwater environments: A bibliometric analysis of the recent literature

1. Species are disappearing at a rate comparable with previous mass extinctions. Freshwater environments are being particularly affected, with biodiversity losses occurring much faster in freshwater than in terrestrial or marine ecosystems.
2. This study assessed the research on drivers of biodiversity loss in freshwater environments as described in nearly 37,000 articles published in the last decade. Articles on biodiversity published between 2010 and 2019 were retrieved from the Web of Science to determine the number of articles that addressed a particular driver of biodiversity loss, by analysing the titles, abstracts, and keywords. The biodiversity and development status of a country was also investigated to see how it affects its scientific output (i.e. number of published articles).
3. Twenty per cent of the articles on biodiversity addressed freshwater biodiversity. Researchers devoted considerable effort to six drivers – climate change, water pollution, flow modification, expanding hydropower, species invasions, and habitat degradation – but practically ignored other threats, such as plastic and light pollution. It was also found that megadiverse countries, which for the most part were also developing countries, published substantially fewer articles than developed but less biodiverse countries.
4. We recommend a series of actions that could contribute to mitigate the biases found in this study.

     

Assessing the distribution pattern of otters in four rivers of the Indian Himalayan biodiversity hotspot

1. The Eurasian otter (Lutra lutra), smooth‐coated otter (Lutrogale perspicillata), and Asian small‐clawed otter (Aonyx cinereus) have all been reported previously from the Indian state of Uttarakhand. However, little information is available about their current distribution in a mountainous region that is subject to increasing human‐induced stressors (such as hydropower plants, pollution, sand and boulder mining, destructive fishing techniques, poaching).
2. Owing to important roles played by these otters in structuring riverine food webs (particularly taking account of their roles as top carnivores), it is critical that they receive suitable protection in the face of projected temperature rise, change in precipitation patterns, and associated river flows in this Himalayan biodiversity hotspot. This study assesses otter distribution in four rivers of Uttarakhand as a basis for informing future conservation actions.
3. Field surveys were conducted (October 2018–January 2019) in reaches of the Kosi, Ramganga, Khoh, and Song rivers, supported by semi‐structured interviews (N = 379) conducted with members of local communities to collect qualitative data on views and perceptions of otter species. In addition, community‐based otter awareness camps were organized for local youths (N = 105), adults (N = 115), and schoolchildren (N = 256 covering 10 schools).
4. Habitat suitability maps were created using remote‐sensing data, survey findings, and a geographic information system to provide information about priority reaches of river to be targeted for future conservation efforts.
5. This study provides critical interdisciplinary baseline information to guide decision‐makers towards developing a targeted, otter‐specific conservation programme for this important Himalayan biodiversity hotspot.
6. The otter conservation education programmes conducted during this study resulted in a proposal to set up a community‐based conservation initiative to monitor and report otter sightings from the area, potentially representing a way forward for achieving simultaneous otter conservation and associated ecosystem benefits for local communities.