Seasonal Abundance and Species Richness of Birds in Common Reed Habitats in Lake Erie

Abstract: Common reed (Phragmites australis) forms dense stands with deep layers of residual organic matter that negatively affects plant diversity and possibly habitat use by wetland birds. We sought to determine whether seasonal relative abundance and species richness of birds varied among 3 habitat types in Great Lakes coastal wetland complexes recently invaded by common reed. We used fixed-distance point counts to determine species relative abundances and species richness in edge and interior locales within common reed, cattail (Typha spp.), and meadow marsh habitats of various sizes during 2 summers (2001 and 2002) and 1 autumn (2001) at Long Point, Lake Erie, Ontario, Canada. We found that total relative abundance and species richness of birds were greater in common reed habitat compared to cattail or meadow marsh habitats. However, we also found that relative abundance of marsh-nesting birds was greater in meadow marsh habitat than in cattail and common reed during summer. Lastly, we found that, irrespective of habitat type, habitat edges had higher total relative abundance and species richness of birds than did habitat interiors. Our results show that common reed provides suitable habitat for a diversity of landbirds during summer and autumn but only limited habitat for many marsh-nesting birds during summer. Based on these results, we recommend restoration of meadow marsh habitat through reduction of common reed in Great Lakes wetlands where providing habitat for breeding marsh-nesting birds is an objective. Managers also might consider reducing the size of nonnative common reed stands to increase edge effect and use by birds, possibly including wetland birds.     

The interacting effects of herbivore exclosures and seed addition in a wet meadow

Seed limitation may prevent successful restoration of native plant communities. Seed addition is a common restoration practice but the role of small mammals in affecting seedling recruitment is not well understood. The purpose of this investigation was to test the relative effect of seed introduction in combination with small mammal and bird exclosures in an Ohio wet meadow. We ask whether the ambient population of Microtus pennsylvanicus (1) alters species composition (e.g. forb/grass/sedge, invasive, non-native); (2) influences plant diversity; and (3) reduces the effect of increasing local plant richness through seed introductions. We established a 2×2 factorial design including a seed addition treatment (0 and 20 seed species added) and an exclosure treatment (open and fenced to exclude all mammalian and bird herbivores and granivores). Seeds from twenty native species were selected to represent a broad range of plant life forms typically found in temperate eastern North American wet meadow communities. All species were obligate or facultative wetland species with forbs, grasses and sedges represented. We found that forb species increased inside exclosures, especially in the seed addition treatment. We also found that relative biomass of invasive species was reduced in exclosures and with seed addition. Species richness increased with seed addition; however, exclosures significantly increased species richness and diversity, particularly of those species that were experimentally introduced by seed. Our results support the seed limitation hypotheses. It is also evident that seed and seedling predation are important factors that can control wet meadow community composition and diversity.     

Longitudinal evaluation of vegetation richness and cover at wetland compensation sites: implications for regulatory monitoring under the Clean Water Act

There has been regulatory concern over the appropriate length of time to monitor wetland sites restored or created as compensation for impacts permitted by a U.S. Clean Water Act permit. However there is very little longitudinal research on wetland compensation sites, and conclusions on compensation site development are usually drawn from the analysis of a chronosequence of sites of different ages. This approach has limitations, given the extent of changes in wetland compensation practices and performance standards over the past few decades. In this study we conducted vegetation surveys of 22 wetland compensation sites in a rapidly developing part of the Minneapolis-St. Paul metropolitan area in 1997 and 2010. We present data on changes over time in floristic richness and cover at the site level and at the level of wetland community type within each site. Our findings do not support the assumption that wetland compensation sites progress on a trajectory toward increasing diversity, floristic quality, or native cover over time. We find that, when data from all sites are considered together, emergent communities have suffered significant declines in both floristic quality and native plant cover, while wet meadow communities have gained species richness but not species diversity. There is some evidence that site richness and cover characteristics are converging toward a regional mean over time, as the species composition of wet meadows became significantly more similar over the survey period, and all community types have significant increases in woody cover. Our study suggests the importance of selecting appropriate compensation sites that avoid foreseeable hydrologic stresses, and does not support the position that 5 years of monitoring can assure the ongoing biotic integrity of wetland compensation sites.     

天津滨海滩涂湿地鸟类丰富度与环境因子的关系研究

由于湿地生态系统的重要性、脆弱性和复杂性,湿地生态系统的保护与修复是当今世界的热点与难点问题之一。本研究选取天津滨海新区的3处湿地生态系统作为参考场地,1处湿地生态系统作为验证场地,通过量化4处场地不同类型栖息地的7个环境因素,综合鸟类对各类型栖息地的使用情况,并采用逐步回归分析,结果表明植被覆盖率、植物水平斑块丰富度及人为干扰程度与鸟类物种丰富度呈显著相关,并建立模型1;植物香农－威纳指数、植物水平斑块丰富度及人为干扰程度与鸟类共位群丰富度呈显著相关关系,并建立模型2。最后,利用验证场地的数据进行模型验证,得出所建立的模型能够较为准确地对栖息地内的鸟类丰富度进行预测。该研究构架了1种利用栖息地类型预测场地鸟类丰富度的方法,以期供相关研究或实际规划设计工作参考。     

Effects of local and landscape-scale habitat variables on abundance and reproductive success of wetland birds

Both local and landscape-scale habitat variables influence the abundance of wetland breeding birds. Few studies, however, simultaneously assess the effects of habitat variables at multiple spatial scales or consider effects on reproductive success. Therefore, we examined the effects of wetland and landscape-scale habitat variables on the abundance of nine breeding bird species and the effects of nest, wetland, or landscape-scale habitat variables on the nest success, clutch size, or number of fledglings of four species at 15 cattail (Typha sp.)-dominated wetlands in an agricultural region around Peterborough, Ontario, Canada. The abundance of Least Bittern (Ixobrychus exilis), Common Moorhen (Gallinula chloropus), and Marsh Wren (Cistothorus palustris) increased as wetland water depth increased; the abundance of Common Moorhen and Marsh Wren increased as wetland size increased; and the abundance of Marsh Wren increased as the amount of wetland in the surrounding landscape increased. Red-winged Blackbird (Agelaius phoeniceus) nest success decreased as nest cover increased. Clutch sizes were uninfluenced by the habitat variables that we considered. The number of Red-winged Blackbird fledglings per successful nest increased as wetland size increased and as the amount of wetland in the surrounding landscape increased. We speculate that food limitation in small wetlands may be responsible for the pattern in Red-winged Blackbird fledging success. The abundance and nest success of Virginia Rail (Rallus limicola) and Sora (Porzana carolina) were uninfluenced by the habitat variables we considered. Future research should consider mate attraction and productivity in relation to local and landscape-scale habitat variables for these and other secretive species. Our study suggests that wetland conservation will be most effective if it considers habitat variables at multiple spatial scales.     

Habitat heterogeneity drives bird species richness,nestedness and habitat selection by individual species in fluvial wetlands of the Paraná River,Argentina

We assessed the relationship between habitat heterogeneity and bird species richness and composition within wetlands of the floodplain of the Middle Paraná River, Argentina. Given the high habitat heterogeneity in these wetland systems, we sought to determine whether (i) there was a positive relationship between bird species richness and habitat heterogeneity; (ii) whether bird species richness was associated with certain types of individual habitat types; (iii) whether there was a pattern of species nestedness and turnover between sites as a function of habitat heterogeneity and composition, respectively; and (iv) whether individual species exhibited associations with habitat heterogeneity. Point counts were used to survey birds at 60 sites. We estimated the area of eight habitat types found within a 200‐m radius from the centre of each site and calculated number and Pielou's evenness of habitat types. These indices, together with area proportion of each habitat type, were used as explanatory factors of bird species richness in linear regression models. Habitat heterogeneity per se rather than area of individual habitat types was a more important predictor of species richness in these fluvial wetlands. Sites with more habitat types supported more bird species. Results showed that individual bird species were associated with different habitat types and, therefore, sites that contained more habitat types contained more species. Number of habitat types accounted for species nestedness between sites whereas composition of habitat types accounted for species turnover between sites. Results suggest that selection of heterogeneous sites by individual species could help explain the positive heterogeneity–species richness relationship. Our findings highlight the importance of habitat heterogeneity per se resulting from flood disturbances in maintaining bird richness in fluvial systems.     

Invasive species removal increases species and phylogenetic diversity of wetland plant communities

Plant invasions result in biodiversity losses and altered ecological functions, though quantifying loss of multiple ecosystem functions presents a research challenge. Plant phylogenetic diversity correlates with a range of ecosystem functions and can be used as a proxy for ecosystem multifunctionality. Laurentian Great Lakes coastal wetlands are ideal systems for testing invasive species management effects because they support diverse biological communities, provide numerous ecosystem services, and are increasingly dominated by invasive macrophytes. Invasive cattails are among the most widespread and abundant of these taxa. We conducted a three‐year study in two Great Lakes wetlands, testing the effects of a gradient of cattail removal intensities (mowing, harvest, complete biomass removal) within two vegetation zones (emergent marsh and wet meadow) on plant taxonomic and phylogenetic diversity. To evaluate native plant recovery potential, we paired this with a seed bank emergence study that quantified diversity metrics in each zone under experimentally manipulated hydroperiods. Pretreatment, we found that wetland zones had distinct plant community composition. Wet meadow seed banks had greater taxonomic and phylogenetic diversity than emergent marsh seed banks, and high‐water treatments tended to inhibit diversity by reducing germination. Aboveground harvesting of cattails and their litter increased phylogenetic diversity and species richness in both zones, more than doubling richness compared to unmanipulated controls. In the wet meadow, harvesting shifted the community toward an early successional state, favoring seed bank germination from early seral species, whereas emergent marsh complete removal treatments shifted the community toward an aquatic condition, favoring floating‐leaved plants. Removing cattails and their litter increased taxonomic and phylogenetic diversity across water levels, a key environmental gradient, thereby potentially increasing the multifunctionality of these ecosystems. Killing invasive wetland macrophytes but leaving their biomass in situ does not address their underlying mechanism of dominance and is less effective than more intensive treatments that also remove their litter.     

扎龙湿地不同生境的昆虫多样性

为了探讨湿地不同生境对昆虫物种多样性的影响,对扎龙湿地8种生境的昆虫进行了系统调查.共捕获昆虫5822只,分属11目58科143种,其中直翅目、双翅目、蜻蜒目为扎龙湿地的优势类群.不同生境中,草原草甸昆虫多样性最高,湖边生境多样性指数和均匀度指数均较高,杂草甸均最低.聚类分析和主分量分析结果表明,不同生境的昆虫群落相似性与水资源状况和植被类型有关,捕食性类群种类数和个体数量对昆虫群落稳定性具有重要的调控作用.湖边生境昆虫群落稳定性最强,湿草甸稳定性最弱.湿地水资源状况能影响昆虫生存生境,进而影响昆虫群落的组成和分布格局.     

Cedar Infestation Impacts Avian Communities along the Niobrara River Valley,Nebraska

Habitat modification has the potential to cause changes in structure and composition of bird communities. Our goal was to determine the response of Songbird community composition to eastern red cedar (Juniperus virginiana) removal in The Nature Conservancy's Niobrara Valley Preserve, Nebraska. We used point counts to survey birds in the riparian matrix of grassland and forest habitats. More than 60 species were recorded on surveys during 2004–2005. We also use the program PRESENCE to determine the response of five species to various habitat components, including cedar density: House Wren (Troglodytes aedon), Spotted Towhee (Pipilo maculates), Ovenbird (Seiurus aurocapillus), Red‐eyed Vireo (Vireo olivaceus), and Indigo Bunting (Passerina cyanea). Species richness estimates were highest in open and mixed habitat patches. Local populations of Ovenbirds and Red‐eyed Vireos responded positively to cedar density, whereas House Wren numbers declined as cedar density increased. Cedar abundance explained the most variation in bird community similarity between survey points; species richness increased as cedar density decreased. Habitat structure and composition drove variation in community composition and population abundance at fine, local scales within the Preserve. Fine‐scale management to remove cedar from local areas should increase diversity of avian species by maintaining a matrix of habitat types. Cedar removal at any scale will affect the composition of bird communities, and we encourage a structured approach to management decisions.     

Relationship between the presence of House Sparrows (<Emphasis Type="Italic">Passer domesticus</Emphasis>) and Neotropical bird community structure and diversity

Invasive exotic species pose an important threat to biodiversity worldwide. However, there is little information on the effects that specific exotic bird species have on native biota. The House Sparrow is an excellent ecological model to evaluate the effect that an invasive exotic species has on native bird communities. Our study describes the relationship of the presence and abundance of House Sparrows with the structure, diversity, and composition of native bird communities in West Mexico. We used two approaches to compare House Sparrow invaded and non-invaded bird communities: (1) at a small geographic-scale that allowed us to evaluate shifts in avian communities with presence of the House Sparrow under similar environmental conditions; and (2) at the landscape-level to evaluate the effect of this species under a scenario of greater environmental heterogeneity. Results from both approaches show that areas invaded by House Sparrows have heavily-dominated avian communities with low species richness, while non-invaded areas exhibit highly-even and species-rich bird communities. Species turnover analysis indicates that the decrease in the number of bird species in House Sparrow invaded areas is caused by species loss, rather than a shift in species composition. Our results indicate that the invasion of an area by the House Sparrow, through synergistic interactions with human activities, determines the composition, structure, and diversity of native bird communities.     

Evaluating the realized niche and plant–water relations of wetland species using experimental transplants

Wet meadows are a common focus of wetland restoration efforts, and the species within them often exist within a restricted range of water levels. Unfortunately, many restored wetlands have higher water levels and more open water than naturally occurring reference wetlands, and many are invaded and dominated by species of Typha. Most studies evaluating the optimal water level for plant species use observational methods, yet experimental methods are required to understand the breadth of a species’ niche. We used experimental transplants of Carex pellita, a common wet meadow sedge used in restoration in the interior of the USA, and Typha latifolia, a species of cattail which invades many restored wetlands, to test whether higher water levels in a restored wetland were prohibitive to the target sedge species. Physiological and growth measurements were collected on both species. We found that C. pellita grew as well or better when transplanted into the ponded water levels, while T. latifolia had reduced growth when transplanted into the relatively drier meadow conditions. Interestingly, C. pellita was able to adjust its Turgor Loss Point in response to changing water levels. Only recently the assumption of a constant Turgor Loss Point for each species has been questioned. Our results provide evidence that wet meadow species have a broader hydrologic niche than previously thought, and their ability to make physiological adjustments in response to changing water levels may allow them to thrive in areas with widely varying water levels.

     

Comparison of mosquito (Diptera: Culicidae) populations by wetland type and year in the lower river Dal?lven region, Central Sweden

We studied adult mosquito assemblages in six wetlands, representing three types (wet meadow, alder swamp, and bog), in the lower part of the River Dal?lven in Central Sweden during three consecutive years (2000-2002) and evaluated the influence of wetland type and year. Mosquito abundance differed significantly between years but not between wetland types. Mosquito species richness showed no significant variation between years or wetland types. Cluster analysis based on percentage of similarity resulted in three clusters, with high similarity between all wetlands in 2000. Ordination analysis showed that mosquito assemblages were mainly correlated with wetland type and water level increase in the previous month. Hydrological conditions varied between the years and between the wetland types, and our collections also included a year (2000) with extreme flood situations. The floodwater mosquito species Ochlerotatus sticticus was the predominant species with a strong influence on the whole study due to its long-range dispersal ability. The entire region suffered from enormous numbers of Oc. sticticus in 2000. The data from this study provided the basis for the initiation of a mosquito control project in the region.     

Vegetation change in created emergent wetlands (1988–1996) in Connecticut (USA)

Changes in hydrology, water quality and vegetation were evaluated in four palustrine emergent wetland pairs, each including created and reference sites. Located along interstate highways, they were initially sampled in 1988 (Confer and Niering, 1992) and again in 1996. Overall, created sites showed significant decreases in open water and water depth between 1989 and 1996 compared to more stable conditions in reference sites. Total nitrogen was generally higher in created sites compared to reference sites, as was specific conductivity, with chloride levels exceeding 800 mg/L, apparently related to road salt. Emergent plant cover increased from 30 to 39% at three created sites, and decreased at a fourth, whereas reference sites remained relatively stable. Wetland species richness also increased from 31 to 39 species at created sites and 35 to 42 species at reference wetlands between the surveys. By 1996 there was an increase in invasive species, particularly Phragmites australis (common reed) and Lythrum salicaria (purple loosestrife). Phragmites increased from <1 to 15% at created sites, while Lythrum increased at one reference site from <1 to 16%. Typha latifolia (common cattail), dominant in the created wetlands in 1988, decreased from 16 to 5% while Typha angustifolia (narrow-leaved cattail) increased from 2 to 10%. At two created sites experiencing increased sedimentation, Phragmites is now dominant or co-dominant with Typha spp., whereas Carex stricta (tussock sedge) and T. latifolia continue to dominate at reference sites. At the one created, permanent flow-through-hydrology wetland, a three-fold decrease in T. latifolia and an eight-fold increase in Phragmites cover have occurred, the latter correlated with sedimentation from road culverts. Increases in alien or invasive species such as Phragmites and Lythrum can serve as indicators of wetland disturbance. Although these created wetlands provide the services of sediment retention, flood storage, and wildlife habitat, a greater range of wetland functions should be possible by constructing two-tiered systems that remove excess sediments and nutrients upstream of the wetland designed to compensate for wetland loss.     

太白山北坡夏秋季鸟类物种多样性

2006年5月～7月(夏季),9月～10月(秋季)在秦岭主峰太白山的北坡根据海拔和典型植被划分生境类型,在6种生境中选择典型样区划定样线并采用样线法对鸟类进行调查,根据鸟类的绝对数量和估算面积计算鸟类的绝对密度,并根据密度等级划分各生境类型中优势物种和常见物种。共观察到鸟类144种,其中留鸟102种,夏候鸟41种,冬候鸟1种。不同的海拔和不同生境类型中的鸟类物种丰富度和多度有较大差异,而且同一生境中鸟类多样性的季节性变化也很明显。无论是夏季还是秋季,低海拔农田带生境中鸟类的总密度最高,而高山灌丛草甸生境中的鸟类总密度最低。优势物种和常见物种在不同的生境类型组成也不相同,而且在不同季节也有变化。夏秋季的鸟类食性组成在农田带有显著差异,而其它生境类型中的鸟类食性夏秋季无明显差异,但是秋季植食性鸟类在各个生境类型中都有增多的趋势。物种丰富度和海拔梯度的关系显示在中海拔地区的鸟类丰富度最高。总体上,和20世纪80年代相比,太白山北坡的鸟类已经发生了明显的变化。     

澳门城市栖息地斑块中鸟类群落功能和谱系多样性

了解群落构建过程是生态学的核心和基本问题,这对于解释物种共存和物种多样性的维持,完善生物多样性保护政策至关重要。与传统的物种多样性相比,功能和谱系多样性能够提供更多的信息,特别是在群落构建过程方面提供深刻见解。2014年5月—2017年1月,采用样线法对澳门地区5个城市栖息地斑块中(生态一区、鹭鸟林、赛马场滩涂、关闸口岸滩涂和莲花桥侧红树林)的鸟类进行繁殖季和越冬季的调查,共调查14次。利用鸟类丰富度和多度来表征群落的物种多样性,其中多度以最大值保留法计;功能和谱系多样性分别采用功能丰富度(functional richness:FRic)和Faith'PD。同时,利用基于多度加权的平均成对功能距离(mean pairwise functional distance,MFD)和平均成对谱系距离(mean pairwise phylogenetic distance,MPD)来表征群落的功能和谱系结构。结果表明:共记录98种鸟类,隶属于14目32科,目、科、种中数量最多的依次为,雀形目鸟类最多为47种,鹭科物种数为11种,白鹭多度为849只;鸟类物种丰富度(68种)和PD在生态一区最高,多度在莲花桥侧红树林最高为2940只,MFD和FRic在赛马场滩涂最高,MPD在生态一区最高;斑块面积在鸟类丰富度、多度、FRic和PD中具有普遍重要性,植被面积和滩涂面积则分别强烈影响着MFD和MPD;关闸口岸滩涂和莲花桥侧红树林的鸟类群落SES.MFD显著低于随机值(P <0. 05),鹭鸟林和赛马场滩涂的鸟类群落SES. MPD显著低于随机值(P<0.05),表明关闸口岸滩涂和莲花桥侧红树林鸟类群落功能聚集(functional clustering),可能与生境过滤驱动群落构建有关。栖息地斑块的特征差异导致了鸟类群落构建机制的不同,这是仅仅考虑物种多样性难以提供的信息,说明了研究群落构建机制时考虑多维度多样性的必要性。     

Response of Plant Height,Species Richness and Aboveground Biomass to Flooding Gradient along Vegetation Zones in Floodplain Wetlands,Northeast China

Flooding regime changes resulting from natural and human activity have been projected to affect wetland plant community structures and functions. It is therefore important to conduct investigations across a range of flooding gradients to assess the impact of flooding depth on wetland vegetation. We conducted this study to identify the pattern of plant height, species richness and aboveground biomass variation along the flooding gradient in floodplain wetlands located in Northeast China. We found that the response of dominant species height to the flooding gradient depends on specific species, i.e., a quadratic response for Carex lasiocarpa, a negative correlation for Calamagrostis angustifolia, and no response for Carex appendiculata. Species richness showed an intermediate effect along the vegetation zone from marsh to wet meadow while aboveground biomass increased. When the communities were analysed separately, only the water table depth had significant impact on species richness for two Carex communities and no variable for C. angustifolia community, while height of dominant species influenced aboveground biomass. When the three above-mentioned communities were grouped together, variations in species richness were mainly determined by community type, water table depth and community mean height, while variations in aboveground biomass were driven by community type and the height of dominant species. These findings indicate that if habitat drying of these herbaceous wetlands in this region continues, then two Carex marshes would be replaced gradually by C. angustifolia wet meadow in the near future. This will lead to a reduction in biodiversity and an increase in productivity and carbon budget. Meanwhile, functional traits must be considered, and should be a focus of attention in future studies on the species diversity and ecosystem function in this region.     

陕西省黄河中游湿地冬季鸭科鸟类群落结构

2002～2007年冬季,对黄河中游湿地4种典型生境包括滩涂、人工渔塘、芦苇沼泽和莲池中的鸭科鸟类群落进行了调查.共记录到鸭科鸟类7属20种,采用频率指数法确定的优势种为斑嘴鸭、绿翅鸭、赤膀鸭、绿头鸭、普通秋沙鸭,其数量之和占总数量的65.6%.对4种不同生境的物种多样性、丰富度、均匀度、优势度进行分析,结果表明芦苇沼泽的多样性和丰富度指数最高,莲池的多样性和丰富度指数最低.人类活动引起的隐蔽场所和食物资源的变化是造成分布差异的主要原因.     

Avian Use of Wetlands in Reclaimed Minelands in Southwestern Indiana

We studied the use of mineland wetlands by birds and the relationship between avian communities and wetland characteristics. Data were collected from 20 wetlands in Pike County, Indiana, and included wetland size, depth, water conductivity and salinity, aquatic macroinvertebrate abundance, vegetation, and bird use. Principal component analysis showed that physical variables could be explained by two principal component scores and that wetlands could be grouped on the basis of size and conductivity. Principal component analysis could not reduce vegetation variables to fewer principal component scores, meaning that wetland vegetation characteristics were independent of one another and did not show any trend. Most wetlands had low invertebrate density, and wetlands with higher invertebrate density had low invertebrate diversity. Wetlands with similar habitat characteristics (physical, vegetative, and invertebrate) did not necessarily show similarities in bird assemblages. Bird similarity index values ranged from 0 to 59%, implying that each wetland has its own bird community. Stepwise multiple regression analysis (α= 0.05) relating bird use and habitat characteristics showed that bird species richness increased with the species richness of submergent vegetation and was correlated negatively with the species richness of emergent vegetation. There was no significant relationship between bird species richness or bird species diversity and wetland size. The number of species within different avian guilds correlated with different habitat characteristics. The species richness of submergent plants was a factor that correlated positively with the number of species of several guilds (dabblers, wading birds, and plunge divers). Wetland age was not a factor that determined bird use.     

Is consolidation drainage an indirect mechanism for increased abundance of cattail in northern prairie wetlands?

In the Prairie Pothole Region of North America, disturbances to wetlands that disrupt water-level fluctuations in response to wet–dry climatic conditions have the potential to alter natural vegetative communities in favor of species that proliferate in stable environments, such as cattail (Typha spp.). We evaluated the effect of water-level dynamics during a recent fluctuation in wet–dry conditions on cattail coverage within semipermanently and permanently ponded wetlands situated in watersheds with different land use and amounts of wetland drainage. We found that ponded water depth increase was significantly greater in wetlands where water levels were not near the spill point of the topographic basin, where banks were steeper, and in larger wetlands where past dry conditions had less influence on change in pond area. Proportion of the wetland covered by cattail was negatively correlated with increased water depth, bank slope and pond area. Our observations provide evidence that cattail coverage in prairie wetlands is regulated by water-level fluctuations and that land use surrounding the wetland might have an indirect effect on cattail coverage by altering water-level response to wet–dry climate conditions. For example, drainage of smaller wetlands into larger wetlands that are characterized by more permanent hydroperiods, leads to stabilized water levels near their spill point and is therefore a potential mechanism for increased cattail abundance in the northern prairie region.     

Validating bird diversity indicators on farmland in east-central Alberta,Canada

Birds can be used as indicators to monitor success of programs encouraging prairie landowners to increase biodiversity. Using a case study from Alberta, Canada, this paper compares bird diversity measures at the farm scale and examines their consistency across different habitat types to test for design, output, and end use validation. Based on 2005 point count data (two types) from 178 sites at 22 farms, we calculated bird species richness, abundance, Shannon index, and Inverse Simpson index.The 50 m radius data produced species richness and abundance measures about half the size as those produced by the unlimited radius data. The bird diversity measures were consistent across habitat types. The 50 m radius data showed differences among 3–5 habitat types, whereas the unlimited radius data showed differences between only two habitat types. Using any bird diversity measure, the wetland/riparian habitat scored highest, followed by homestead, upland forest, native prairie, tame pasture, and cultivated land habitats.Bird monitoring methods should favor fixed over unlimited radius point counts, because of the former's greater discriminating ability. Given that diversity measures are consistent across habitats and are highly correlated, the species richness measure, which is simple and easy to understand, can be used in conversations with landowners and policy-makers.