Using multi-scale species distribution data to infer drivers of biological invasion in riparian wetlands

Aim Biological invasion is a major conservation problem that is of interest to ecological science. Understanding mechanisms of invasion is a high priority, heightened by the management imperative of acting quickly after species introduction. While information about invading species’ ecology is often unavailable, species distribution data can be collected near the onset of invasion. By examining distribution patterns of exotic and native plant species at multiple spatial scales, we aim to identify the scale (of those studied) that accounts for most variability in exotic species abundance, and infer likely drivers of invasion. Location River Murray wetlands, south‐eastern Australia. Methods A nested, crossed survey design was used to determine the extent of variation in wetland plant abundance, grazing intensity and water depth at four spatial scales (reaches, wetland clumps, wetlands, wetland sections), and among three Depth‐strata. We examined responses of exotic and native species groups (grouped into terrestrial and amphibious taxa), native weeds and 10 individual species using hierarchical ANOVA. Results As a group dominated by terrestrial taxa, exotic species cover varied at reach‐, wetland‐ and section‐scales. This likely reflects differences in abiotic characteristics and propagule pressure at these scales. Groups based on native species did not vary at any scale examined. Cover of 10 species mostly varied among and within wetlands (patterns unrelated to species’ origin or functional group), but species’ responses differed, despite individual plants being similar in size. While flora mostly varied among wetlands, exotic cover varied most among reaches (26%), which was attributed to hydrological modification and human activities. Main conclusions Multi‐scale surveys can rapidly identify factors likely to affect species’ distributions and can indicate where future research should be directed. By highlighting disproportionate variation in exotic cover among reaches, this study suggests that flow regulation and human‐mediated dispersal facilitate exotic plant invasion in River Murray wetlands.     

Consideration of Geography and Wetland Geomorphic Type in the Development of Great Lakes Coastal Wetland Bird Indicators

We examined how geographic distribution of birds and their affinities to three geomorphic wetland types would affect the scale at which we developed indicators based on breeding bird communities for Great Lakes coastal wetlands. We completed 385 breeding bird surveys on 222 wetlands in the US portion of the basin in 2002 and 2003. Analyses showed that wetlands within two ecoprovinces (Laurentian Mixed Forest and Eastern Broadleaf Forest) had different bird communities. Bird communities were also significantly different among five lakes (Superior, Michigan, Huron, Erie, and Ontario) and among three wetland types (lacustrine, riverine, barrier-protected). Indicator values illustrated bird species with high affinities for each group (ecoprovince, lake, wetland type). Species with restricted geographic ranges, such as Alder and Willow Flycatchers (Empidonax alnorum and E. traillii), had significant affinities for ecoprovince. Ten bird species had significant affinities for lacustrine wetlands. Analyses on avian guild metrics showed that Lake Ontario wetlands had fewer long-distant migrants and warblers than other lakes. Numbers of short-distant migrants and total individuals in wetlands were higher in the Eastern Broadleaf Forest ecoprovince. Number of flycatchers and wetland obligate birds were not different among provinces, lakes, or wetland type. One potential indicator for wetland condition in Great Lakes wetlands, proportion of obligate wetland birds, responded negatively to proportion of developed land within 1 km of the wetland. We conclude that, although a guild approach to indicator development ameliorates species-specific geographic differences in distribution, individual species responses to disturbance scale will need to be considered in future indicator development with this approach.     

Exotic vascular plant invasiveness and forest invasibility in urban boreal forest types

The riverine forests of the northern city of Edmonton, Alberta, Canada display strong resilience to disturbance and are similar in species composition to southern boreal mixedwood forest types. This study addressed questions such as, how easily do exotic species become established in urban boreal forests (species invasiveness) and do urban boreal forest structural characteristics such as, native species richness, abundance, and vertical vegetation layers, confer resistance to exotic species establishment and spread (community invasibility)? Eighty-four forest stands were sampled and species composition and mean percent cover analyzed using ordination methods. Results showed that exotic tree/shrub types were of the most concern for invasion to urban boreal forests and that exotic species type, native habitat and propagule supply may be good indicators of invasive potential. Native forest structure appeared to confer a level of resistance to exotic species and medium to high disturbance intensity was associated with exotic species growth and spread without a corresponding loss in native species richness. Results provided large-scale evidence that diverse communities are less vulnerable to exotic species invasion, and that intermediate disturbance intensity supports species coexistence. From a management perspective, the retention of native species and native forest structure in urban forests is favored to minimize the impact of exotic species introductions, protect natural succession patterns, and minimize the spread of exotic species.     

Development of community metrics to evaluate recovery of Minnesota wetlands

Monitoring wetland recovery requires assessment tools that efficiently and reliably discern ecosystem changes in response to changes in land use. The biological indicator approach pioneered for rivers and streams that uses changes in species assemblages to interpret degradation levels may be a promising monitoring approach for wetlands. We explored how well metrics based on species assemblages related to land use patterns for eight kinds of wetlands in Minnesota. We evaluated land use on site and within 500 m,1000 m, 2500 m and 5000 m of riverine, littoral, and depressional wetlands (n = 116) in three ecoregions. Proportion of agriculture, urban, grassland, forest,and water were correlated with metrics developed from plant, bird, fish, invertebrate, and amphibian community data collected from field surveys. We found79 metrics that relate to land use, including five that may be useful for many wetlands: proportion of wetland birds, wetland bird richness, proportion of insectivorous birds, importance of Carex, importance of invasive perennials. Since very few metrics were significant for even one-half of the wetland types surveyed, our data suggest that monitoring recovery in wetlands with community indicators will likely require different metrics,depending on type and ecoregion. In addition, wetlands within extensively degraded ecoregions may be most problematic for indicator development because biotic degradation is historic and severe. This revised version was published online in July 2006 with corrections to the Cover Date.     

Carbon storage dynamics of temperate freshwater wetlands in Pennsylvania

Healthy wetlands play a significant role in climate change mitigation by storing carbon that would otherwise contribute to global warming, leading to the reduction of water and food resources as well as more extreme weather phenomena. Investigating the magnitude of carbon storage potential of different freshwater wetland systems using multiple ecological indicators at varying spatial scales provides insight and justification for selective wetland restoration and conservation initiatives. We provide a holistic accounting of total carbon values for 193 wetland sites, integrating existing carbon algorithms to rapidly assess each of the following carbon pools: above-ground, below-ground, soil, woody debris, shrub cover, and herbaceous cover. Aspects of soil, vegetation, and ecosystem characteristics and stressors were measured to obtain an overall understanding of the ecosystems ability to store carbon (long-term) along a gradient of human disturbance. Based on a review of the literature, methods were prioritized based on the initial data available from field measurements as well as their practicality and ease in replicating the process in the future. Lacustrine human impounded (88.7?±?18.0 tC/ha), riverine beaver impounded (116.2?±?29.4 tC/ha), riverine upper perennial (163.3?±?11.8 tC/ha), riverine lower perennial (199.2?±?24.7 tC/ha), riverine headwater complex (159.5?±?22.2 tC/ha), perennial/seasonal depression (269.6?±?42.4 tC/ha), and slope (162.2?±?14.6 tC/ha) wetland types were compared. Overall results showed moderate variability (9.33–835.95 tC/ha) for total carbon storage values across the wetland types, with an average total carbon storage of 174.6?±?8.8 tC/ha for all wetlands. Results show that carbon storage was significantly higher (p?=?0.002) in least disturbed wetland sites. Apart from perennial/seasonal depression wetlands, all reference standard wetlands had greater carbon storage, less disturbance impact, and a greater extent of forest cover than non-reference wetlands. Carbon storage values calculated were comparable to published literature.     

The influence of urban land use on seed dispersal and wetland invasibility

Urban habitats are generally considered highly invaded by exotic species due to the frequency and extent of disturbance caused by human activities and development. Our previous study had demonstrated that forested wetlands within residential areas are more extensively invaded than wetlands within industrial–commercial areas. In this study, we investigate whether the structure of the forest edge and seed dispersal can explain the differential in the invasion of wetlands surrounded by industrial and residential land use. Our results indicate that edges of industrially bordered wetlands are denser, with vegetation concentrated at the boundary of tree growth, whereas the edges of residentially bordered wetlands are more open and diffuse. This difference influences the number of seeds and species capable of dispersing into the wetland. Less dense edges resulted in a higher number of seeds entering residential wetlands; however, there were no differences in the numbers of exotic seeds or exotic species in the seed rain residential and industrial wetlands. Although seed dispersal could not directly explain differences in the current extent of invasion of these sites, seed dispersal did follow corridor pathways, including ditches and trails that breach the edges and extend through the wetlands. These disturbances act as corridors for seed dispersal into both types wetlands and may play a role in introducing new species to the interior of the wetland, an outcome supported by a higher number of exotic species in the seed banks of residential sites. Our results suggest that both the type of adjoining land use and the provision of access to people on trails in urban wetlands can affect the composition of these communities.     

Spatial genetic analysis of two polyploid macrophytes reveals high connectivity in a modified wetland

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Plant invasions in arid areas: special problems and solutions: a South African perspective

Management of invasive alien plants in arid areas is complicated by the cryptic and stochastic nature of the invasion process, the low density of researchers, extension officers and farmers in these areas, the complex, delayed and sometimes, indirect, effects of alien invasive plants on these ecosystems, and by high and shifting values placed on goods and services derived from invasive alien plant species. Fluctuating vegetation cover together with convergent adaptations for dispersal and facilitation enables some desert aliens to invade intact vegetation. Invasive plants in arid areas are not all arid-adapted: the most problematic species globally are phreatic, wetland or oasis specialists that can colonise remote wetlands and springs through a combination of wind-dispersed seeds and vegetative reproduction. Their success is often linked to disturbance and facilitated by agricultural activities including water extraction, cropping and livestock management. Invasive alien plants in arid region wetlands have an impact on forage, water resources and biodiversity in these key resource areas, that is disproportionately great relative to the area they occupy. Management of arid region aliens could include pre-introduction biocontrol planning that makes it possible to use aliens while reducing invasion risks. An alternative is to replace the aliens with extralimital indigenous plants that can supply the rangeland services perceived to be absent from arid environments—but such interventions may carry even greater risks.     

气候变化与人类活动对青藏高原湿地的影响研究进展

青藏高原是中国湿地分布最多的区域,其独特的高寒湿地对区域生态环境安全有着不可或缺的作用。梳理了青藏高原湿地变化的时空特征,基于此,重点分析了气候变化与人类活动对不同类型湿地的影响和作用机制。研究发现：(1)主导不同类型湿地变化的气候因素有差异,影响存在区域异质性。湖泊湿地主要受降水量影响,湖泊湿地在北部扩张、南部缩小的趋势与降水量的空间差异存在较强的一致性;沼泽湿地主要受气温影响,气温升高导致水分蒸发、植被群落演替,沼泽湿地向草地转化,江河源区和若尔盖高原等主要分布区域呈现退化趋势;河流湿地主要受气温影响,气温升高加速河源冰川消融、同时也增大河流蒸散发量,共同作用下河流湿地呈现北部减少、南部增加的趋势。(2)过度放牧、泥炭开采、水利建设等是影响湿地变化的主要人类活动。若尔盖高原同时存在过度放牧、泥炭开采和沟渠建设多重人类活动影响,当地沼泽湿地退化明显;柴达木盆地的人工湿地由于盐业开采迅速扩张。(3)当前研究存在数据可对比性不足、大区域尺度和野外定点持续监测数据缺乏等问题,导致对气候变化与人类活动影响机制研究不够深入。未来应加强高寒湿地定期监测与风险评估,完善高寒湿地生态系统与环境变化和...     

Quantifying levels of biological invasion: towards the objective classification of invaded and invasible ecosystems

Biological invasions are a global phenomenon that threatens biodiversity, and few, if any, ecosystems are free from alien species. The outcome of human‐mediated introductions is affected by the invasiveness of species and invasibility of ecosystems, but research has primarily focused on defining, characterizing and identifying invasive species; ecosystem invasibility has received much less attention. A prerequisite for characterizing invasibility is the ability to compare levels of invasion across ecosystems. In this paper, we aim to identify the best way to quantify the level of invasion by nonnative animals and plants by reviewing the advantages and disadvantages of different metrics. We explore how interpretation and choice of these measures can depend on the objective of a study or management intervention. Based on our review, we recommend two invasion indices and illustrate their use by applying them to two case studies. Relative alien species richness and relative alien species abundance indicate the contribution that alien species make to a community. They are easy to measure, can be applied to various taxa, are independent of scale and are comparable across regions and ecosystems, and historical data are often available. The relationship between relative alien richness and abundance can indicate the presence of dominant alien species and the trajectory of invasion over time, and can highlight ecosystems and sites that are heavily invaded or especially susceptible to invasion. Splitting species into functional groups and examining invasion patterns of transformer species may be particularly instructive for gauging effects of alien invasion on ecosystem structure and function. Establishing standard, transparent ways to define and quantify invasion level will facilitate meaningful comparisons among studies, ecosystem types and regions. It is essential for progress in ecology and will help guide ecosystem restoration and management.     

Developing a wetland-type classification system in the Republic of Korea

Though there are wetlands listed by the IUCN and wetland protection areas designated by the government, it is presumed that there would be more wetlands in Korea when they are surveyed and classified according to international wetland criteria, but a considerable amount of area is yet to be identified. Therefore, in order to conduct a systematic status survey on the wetlands of Korea, a wetland classification system needs to be developed first. The objectives of this paper include reviewing international wetland classifications and mapping systems of the USA, Germany, the Netherlands, Japan and North Korea and developing a wetland classification and mapping system appropriate to Korea based on an understanding of the major case examples of wetland types. Then, the developed system was applied to the Phanmun field watershed located at the western DMZ in Korea to conduct a case study. The overall process of a wetland classification and mapping system developed in this study is undertaken as the following from step 1 to step 5. First, wetlands are identified based on three parameters: hydrology, hydrophytes and hydric soil. Second, wetland delineation distinguished wetland areas and non-wetland areas by identifying wetlands through a field survey. Third, an ecological survey is conducted in order to classify wetland characteristics and types for the target area. Ecological survey items include the topography, landscape, biota, pollutant sources and land use status. Fourth, a wetland classification is developed through a hybrid approach based on HGM (the hydrogeomorphic method). Level 1 is classified into inland, estuarine and costal areas. Level 2, the target area, is classified as an eco-region at a watershed level, and level 3 is classified into depression, riverine, slope, flat and fringe areas based on a HGM approach. Level 4 is classified into detailed wetland types based on specific characteristics of wetlands. Level 5 is classified into marsh and swamp based on grasslands and shrubs and forest trees. Level 6 indicates the dominant vegetation communities.

Development of a multimetric plant-based index of biotic integrity for assessing the ecological state of forested,urban and agricultural natural wetlands of Jimma Highlands,Ethiopia

Wetlands are vital natural resources thereby providing ecological and socio-economic benefits to the people. However, anthropogenic activities have seriously changed the ecological conditions of wetlands worldwide, especially in developing nations like Ethiopia. Predominantly, the absence of biomonitoring tool greatly hampers the protection and management of wetlands. Therefore, the objective of this research is to develop a plant-based index of biological integrity for facilitating the management of wetlands. Accordingly, 122 plant species belonging to 37 families were collected and identified from forested, urban and agricultural wetland types and included in the analysis of the plant metrics. Initially, we reviewed and screened 35 potential metrics. Then, we selected four core metrics (% cover of native species, sensitive plant species richness, tolerant plant species richness and% of shrub species richness) using the decrease or increase responses to human disturbances, Mann-Whitney U test and redundant metric test. A trisect-quartile range system using box plots of the reference or impaired sites of wetlands was established to provide values for each core metrics. Then after, we combined the core metrics to develop the plant-based index of biological integrity. Finally, we validated the index by comparing the index response to different wetland types. Additionally, the index was validated based on the measured environmental variables that characterize the human disturbance gradient of wetlands. We found that the plant-based index is robust to discriminate the reference wetlands from impaired wetlands and can also be used as an effective tool for evaluating the long term natural wetland conditions of the Eastern African wetlands in the future.     

Identifying wetland meadows in Grand Teton National Park using remote sensing and average wetland values

Six spectrally and ecologically distinct montane meadow community types were identified and mapped within Grand Teton National Park by analysis of Indian IRS-1B LISS-II imagery. A distinct to-xeric-hydric gradient among the meadow types was predicted by analysis of the satellite data. Thirty sites (five replicates for each of six meadow typ were selected for intensive field sampling. At each of the 30 sites, meadow vegetation was sampled in 20 m by 20 m square plots for canopy cover of all species. Using wetland indexes (on a scale of 1–5, where obligate wetland species = 1, facultative land = 2, facultative = 3, facultative upland = 4 and upland species = 5), average wetland values were calculated and ranged from 1.88 for A-type meadows and 2.86 for B meadows to 4.40, 4.49, 4.74, and 4.43 for C, D, E and F meadows, respectively. Because average wetland values of A and B meadows were < 3.00, they were determined to be indicative of wetlands. Eight out of ten obligate wetland plants had their greatest cover on A meadows (the wettest of the gradient) and had significant cover differe among meadow types using the non-parametric Kruskal-Wallis test. Average wetland values and plant species cover were used, in conjunction with remotely sensed data, to identify as wetlands 1,258 hectares of A meadows and 1,711 hectares of B meadows in Grand Teton National Park.     

Habitat and History Influence Abundance of Bog Turtles

Conservation of rare and endangered species requires assessment of factors that influence the current habitat associations of a species and the role of past habitat degradation in limiting occupancy or abundance. The objective of our 2011–2014 study was to determine how habitat characteristics and wetland history can predict occupancy and abundance patterns of bog turtles (Glyptemys muhlenbergii) at the fringe of their range in the southeastern United States. We used a hurdle model to examine occupancy and abundance patterns while addressing problems associated with zero-inflated data. Occupancy patterns were weakly related to percent of the wetland containing emergent vegetation, whereas abundance patterns were predicted by the percent silt in the wetland substrate, percent forest cover, amount of habitat degradation, and recovery time since past habitat degradation. The effect of historical habitat degradation on abundance rather than occupancy patterns has rarely been documented and its effect is rarely studied in vertebrate populations. Identification of predictors of occupancy and abundance patterns will aid discovery of new populations of bog turtles and improve management of occupied wetlands. © 2019 The Wildlife Society.     

Effects of Local and Landscape Variables on Wetland Bird Habitat Use During Migration Through the Rainwater Basin

ABSTRACT Staging areas and migratory stopovers of wetland birds can function as geographic bottlenecks; common dependence among migratory wetland bird species on these sites has major implications for wetland conservation. Although 90% of playa wetlands in the Rainwater Basin (RWB) region of Nebraska, USA, have been destroyed, the area still provides essential stopover habitat for up to 10 million waterfowl each spring. Our objectives were to determine local (within wetland and immediate watershed) and landscape-scale factors influencing wetland bird abundance and species richness during spring migration at RWB playas. We surveyed 36–40 playas twice weekly in the RWB and observed approximately 1.6 million individual migratory wetland birds representing 72 species during spring migrations 2002–2004. We tested a priori hypotheses about whether local and landscape variables influenced overall species richness and abundance of geese, dabbling ducks, diving ducks, and shorebirds. Wetland area had a positive influence on goose abundance in all years, whereas percent emergent vegetation and hunting pressure had negative influences. Models predicting dabbling duck abundance differed among years; however, individual wetland area and area of semipermanent wetlands within 10 km of the study wetland consistently had a positive influence on dabbling duck abundance. Percent emergent vegetation also was a positive predictor of dabbling duck abundance in all years, indicating that wetlands with intermediate (50%) vegetation coverage have the greatest dabbling duck abundance. Shorebird abundance was positively influenced by wetland area and number of wetlands within 10 km and negatively influenced by water depth. Wetland area, water depth, and area of wetlands within 10 km were all equally important in models predicting overall species richness. Total species richness was positively influenced by wetland area and negatively influenced by water depth and area of semipermanent wetlands within 10 km. Avian species richness also was greatest in wetlands with intermediate vegetation coverage. Restoring playa hydrology should promote intermediate percent cover of emergent vegetation, which will increase use by dabbling ducks and shorebirds, and decrease snow goose (Chen caerulescens) use of these wetlands. We observed a reduction in dabbling duck abundance on wetlands open to spring snow goose hunting and recommend further investigation of the effects of this conservation order on nontarget species. Our results indicate that wildlife managers at migration stopover areas should conserve wetlands in complexes to meet the continuing and future habitat requirements of migratory birds, especially dabbling ducks, during spring migration.     

Dispersal and local environment affect the spread of an invasive apple snail (<Emphasis Type="Italic">Pomacea maculata</Emphasis>) in Florida,USA

Dispersal and local environmental factors are major determinants of invasive species distribution. We examined how both dispersal-related geospatial characteristics and environmental factors influence an ongoing invasion of wetlands in a south-central Florida ranchland by non-native apple snails (Pomacea maculata, Ampullariidae). We found P. maculata in 73 (43%) of a random set of 171 wetlands in 2014. We used model selection to evaluate multiple hypotheses of predictors of P. maculata occurrence in 95 wetlands with standing water, including spatially-explicit distances in ditches from wetlands to the presumed entry point, Euclidean (overland) distances, presence/absence of ditches in wetlands, and environmental variables (e.g. pH). We also performed a 5-month field experiment in 20 wetlands to evaluate if snail absence was associated with conditions that limit survival and growth (i.e. unfavorable habitats). Snail occurrence was primarily associated with presence of ditches in wetlands and more neutral wetland pH. These variables more plausibly explained snail occurrence than did Euclidean (overland) distance and minimum ditch travel (rectilinear) distance from propagule sources (a major waterway). Wetland pH best explained survival and growth under the experimental conditions. We found no evidence that prior occupancy by conspecifics affected survival and growth, suggesting that dispersal limitation may contribute to lack of occupancy of wetlands, despite suitable pH. Our study supports man-made conduits as facilitators of dispersal by non-native species, where environmental characteristics (here pH) then also affect colonization within habitats. An understanding of both dispersal mechanisms and local environmental factors is necessary to better predict invasive species distribution.     

Invasibility of mature and 15-year-old deciduous forests by exotic plants

High species richness, resource availability and disturbance are community characteristics associated with forest invasibility. We categorized commonly measured community variables, including species composition, topography, and landscape features, within both mature and 15-year-old clearcuts in West Virginia, USA. We evaluated the importance of each variable for predicting the degree of forest invasion by early-establishing exotic invasive plants. Biotic variables, including overall richness (excluding exotic invasive species) and mutually exclusive native and exotic non-invasive species richness, were the strongest indicators of invasibility. Sites that were located on northeast-facing slopes, more mesic conditions, or in clearcuts were more likely to be invaded by exotic invasive plants. Invasion of clearcut sites was more dependent on available microsites (e.g., lower solar radiation, northeast-facing slopes, and lower elevations) within each site than on the condition of the surrounding landscape, whereas invasion into the mature forests was dependent more on the surrounding landscape (e.g., proximity to paved roads). Our results indicate that exotic invasive plant species in our study area respond similarly as other plant species to resource availability and that competitive interactions are relatively unimportant. Current invasion into this landscape is more likely to be a passive reaction to site conditions instead of a driver of change.     

Dynamics of sediment carbon stocks across intertidal wetland habitats of Moreton Bay,Australia

Coastal wetlands are known for high carbon storage within their sediments, but our understanding of the variation in carbon storage among intertidal habitats, particularly over geomorphological settings and along elevation gradients, is limited. Here, we collected 352 cores from 18 sites across Moreton Bay, Australia. We assessed variation in sediment organic carbon (OC) stocks among different geomorphological settings (wetlands within riverine settings along with those with reduced riverine influence located on tide‐dominated sand islands), across elevation gradients, with distance from shore and among habitat and vegetation types. We used mid‐infrared (MIR) spectroscopy combined with analytical data and partial least squares regression to quantify the carbon content of ~2500 sediment samples and provide fine‐scale spatial coverage of sediment OC stocks to 150 cm depth. We found sites in river deltas had larger OC stocks (175–504 Mg/ha) than those in nonriverine settings (44–271 Mg/ha). Variation in OC stocks among nonriverine sites was high in comparison with riverine and mixed geomorphic settings, with sites closer to riverine outflow from the east and south of Moreton Bay having higher stocks than those located on the sand islands in the northwest of the bay. Sediment OC stocks increased with elevation within nonriverine settings, but not in riverine geomorphic settings. Sediment OC stocks did not differ between mangrove and saltmarsh habitats. OC stocks did, however, differ between dominant species across the research area and within geomorphic settings. At the landscape scale, the coastal wetlands of the South East Queensland catchments (17,792 ha) are comprised of approximately 4,100,000–5,200,000 Mg of sediment OC. Comparatively high variation in OC storage between riverine and nonriverine geomorphic settings indicates that the availability of mineral sediments and terrestrial derived OC may exert a strong influence over OC storage potential across intertidal wetland systems.     

湿地自然保护区保护价值评价方法

提出了一套侧重水鸟保护的湿地自然保护区保护价值评价方法.该方法建立的指标体系经过专家咨询和会议讨论确定指标,采用层次分析法(AHP)建立了递阶层次结构模型.指标体系共分为目标层1项、系统层5项、准则层11项和指标层26项.将获取资料的湿地自然保护区按国家有关分类标准与原则归为3个类型(海洋与海岸生态系统类型、内陆湿地与水域生态系统类型和野生动物类型),每个类型内的自然保护区再结合自身湿地主体进一步划分为4个小类型(近海与海岸湿地、河流湿地、湖泊湿地、沼泽湿地).实例分析了海洋与海岸生态系统类型中的以近海及海岸湿地为主体的自然保护区,内陆湿地与水域生态系统类型中的以沼泽湿地为主体的自然保护区和野生动物类型中的以河流湿地为主体的自然保护区,并依照保护价值指数进行了等级划分.为湿地自然保护区的保护价值和发展地位,总体规划和改建变更提供了依据.     

Influence of area,habitat and water chemistry on richness and composition of macrophyte assemblages in southern Brazilian wetlands

Questions: Two hypotheses were tested: (1) physical features, such as wetland surface area and habitat diversity, together with water chemistry, are important determinants of species richness and composition of macrophyte assemblages and (2) species richness and composition of macrophyte assemblages differ between wetlands of different types (i.e., palustrine versus lacustrine) and between wetlands of different hydrologies (i.e. permanent versus intermittent). Location: A subtropical coastal plain segment (2500 km²) of southern Brazil. Methods: Quarterly collections were carried out in 15 wetlands (2004–2005) in southern Brazil. Differences in richness over time were tested using repeated measures ANOVA. Stepwise multiple regression was performed to investigate relationships between total richness and environmental variables. Significance of differences between wetland types and hydroperiods on species composition was verified by MRPP (Multi‐Response Permutation Procedure). The influence of the environmental variables on species composition was assessed using CCA (Canonical Correspondence Analysis). Results: Macrophyte species richness changed with time, was not significantly different between wetland types, but was higher in permanent wetlands than in intermittent ones. Area, habitat diversity and soluble reactive phosphorus concentration explained 76% of the variation in species richness. Species composition was different between permanent and intermittent wetlands, although it was not significantly different between wetland types. Area, habitat diversity and water chemistry explained 50.1% of species composition. Conclusions: Species richness and composition of wetland macrophytes were mainly determined by area, habitat diversity and hydroperiod. These results can be used for the development of conservation and management programs in southern Brazil.