Influence Of Vegetation Structure Research Articles

Rewilding Europe's large grazer community: how functionally diverse are the diets of European bison, cattle, and horses?

Trophic rewilding is the introduction of species to restore top–down trophic interactions and associated trophic cascades to promote self‐regulating biodiverse ecosystems. A core example of trophic rewilding is the restoration of large mammalian grazer communities to restore or maintain biodiverse open to half‐open landscapes. Across Europe, cattle and horse breeds are being introduced as substitutes of the extinct aurochs (Bos primigenius) and tarpan (Equus ferus). More recently, European bison (Bison bonasus) is being introduced because it is supposed to fill a niche that pure grazers such as cattle and horses leave empty, especially in terms of reducing woody encroachment. But how functionally diverse are the diets of these three species? We investigated this question in the Kraansvlak pilot; a trophic rewilding project in the Netherlands where European bison, horses, and cattle have been introduced in spatially heterogeneous landscapes of forest, shrub land, and grassland. We present 4 years of data from direct observations on the diet use of all three species. Whereas cattle and bison included a significant proportion of woody plants in their diet throughout the year, horses strictly grazed. However, cattle and bison differed clearly in terms of the woody plant part they used (bark vs. twigs), and we discuss how this may affect the way they influence vegetation structure. Finally, we discuss the implications of our study for the increasing number of trophic rewilding initiatives in Europe.

Influences of spatial variation in vegetation on avian richness and abundance vary by season in the Chihuahuan Desert

Changes in the structure, composition, and distribution of desert vegetation have resulted in altered desert bird communities. One of the most well-known influences on bird diversity and abundance in these ecosystems is the degree of woody shrub dominance. While the influence of vegetation structure and composition gradients on Chihuahuan Desert bird communities of North America has received valuable attention, seasonal variation in these influences is poorly understood. Our goal was to understand how vegetation gradients across space influence bird communities over four seasonal periods. We employed three years of avian survey data and static, spatial vegetation data in generalized linear mixed-effects models, identifying effects of (1) shrub cover in predicting shrubland bird species richness and abundance, (2) grass cover in predicting grassland bird abundance, and (3) grass height in predicting grassland and shrubland species richness and abundance. Effect sizes varied by season, with grass heights exhibiting (1) greatest positive effects on grassland species in the breeding season and (2) greatest negative effects on shrubland species in the winter. In targeting management for birds of the Chihuahuan Desert and other arid regions, managers should consider both bird-habitat associations and the variation in these relationships between seasons.

The importance of vegetation density for tourists' wildlife viewing experience and satisfaction in African savannah ecosystems.

Southern African protected areas (PAs) harbour a great diversity of animals, which represent a large potential for wildlife tourism. In this region, global change is expected to result in vegetation changes, such as bush encroachment and increases in vegetation density. However, little is known on the influence of vegetation structure on wildlife tourists’ wildlife viewing experience and satisfaction. In this study, we collected data on vegetation structure and perceived mammal densities along 196 road transects (each 5 km long) and conducted a social survey with 651 questionnaires across four PAs in three Southern African countries. Our objectives were 1) to assess visitors’ attitude towards vegetation, 2) to test the influence of perceived mammal density and vegetation structure on the easiness to spot animals, and 3) on visitors’ satisfaction during their visit to PAs. Using a Boosted Regression Tree procedure, we found mostly negative non-linear relationships between vegetation density and wildlife tourists’ experience, and positive relationships between perceived mammal densities and wildlife tourists’ experience. In particular, wildlife tourists disliked road transects with high estimates of vegetation density. Similarly, the easiness to spot animals dropped at thresholds of high vegetation density and at perceived mammal densities lower than 46 individuals per road transect. Finally, tourists’ satisfaction declined linearly with vegetation density and dropped at mammal densities smaller than 26 individuals per transect. Our results suggest that vegetation density has important impacts on tourists’ wildlife viewing experience and satisfaction. Hence, the management of PAs in savannah landscapes should consider how tourists perceive these landscapes and their mammal diversity in order to maintain and develop a sustainable wildlife tourism.

How does vegetation structure influence woodpeckers and secondary cavity nesting birds in African cork oak forest?

The Great Spotted Woodpecker provides important information about the status of a forest in terms of structure and age. As a primary cavity creator, it provides small-medium size cavities for passerines. However, despite its interest as an ecosystem engineer, studies of this species in Africa are scarce. Here, spatially explicit predictive models were used to investigate how forest structural variables are related to both the Great Spotted Woodpecker and secondary cavity nesting birds in Maamora cork oak forest (northwest Morocco). A positive association between Great Spotted Woodpecker and both dead-tree density and large mature trees (>60 cm dbh) was found. This study area, Maamora, has an old-growth forest structure incorporating a broad range of size and condition of live and dead trees, favouring Great Spotted Woodpecker by providing high availability of foraging and excavating sites. Secondary cavity nesting birds, represented by Great Tit, African Blue Tit, and Hoopoe, were predicted by Great Spotted Woodpecker detections. The findings suggest that the conservation of the Maamora cork oak forest could be key to maintaining these hole-nesting birds. However, this forest is threatened by forestry practises and livestock overgrazing and the challenge is therefore to find sustainable management strategies that ensure conservation while allowing its exploitation.

Relationships among Vegetation Structure, Canopy Composition, and Avian Richness Patterns across an Aspen-Conifer Forest Gradient

ABSTRACTEcologists have a long-term interest in understanding the relative influence of vegetation composition and vegetation structure on avian diversity. LiDAR remote sensing is useful in studying local patterns of avian diversity because it characterizes fine-scale vegetation structure across broad extents. We used LiDAR, aerial and satellite imagery, and avian field data to investigate the relative influence of vegetation structure and canopy composition on avian richness across an aspen-conifer forest gradient. Aspen enhances forest avian biodiversity but has been declining across western North America. We conducted bird surveys between 2013 and 2014 in plots with a range of aspen-conifer canopy composition. We found aspen to support higher avian richness than conifer, especially among cavity nesters. In contrast to other studies, we found weak relationships between vegetation structure and avian richness. Although primary cavity excavator richness was negatively influenced by canopy density, canopy composition was the most important variable influencing total richness and nesting guild richness. This study adds to the body of literature utilizing LiDAR-derived metrics to better understand local patterns of avian diversity, and provides perspectives on how avian communities might respond to conifer encroachment into aspen.

Tree cover in Central Africa: determinants and sensitivity under contrasted scenarios of global change

Tree cover is a key variable for ecosystem functioning, and is widely used to study tropical ecosystems. But its determinants and their relative importance are still a matter of debate, especially because most regional and global analyses have not considered the influence of agricultural practices. More information is urgently needed regarding how human practices influence vegetation structure. Here we focused in Central Africa, a region still subjected to traditional agricultural practices with a clear vegetation gradient. Using remote sensing data and global databases, we calibrated a Random Forest model to correlatively link tree cover with climatic, edaphic, fire and agricultural practices data. We showed that annual rainfall and accumulated water deficit were the main drivers of the distribution of tree cover and vegetation classes (defined by the modes of tree cover density), but agricultural practices, especially pastoralism, were also important in determining tree cover. We simulated future tree cover with our model using different scenarios of climate and land-use (agriculture and population) changes. Our simulations suggest that tree cover may respond differently regarding the type of scenarios, but land-use change was an important driver of vegetation change even able to counterbalance the effect of climate change in Central Africa.

Habitat Structure Influences the Diversity, Richness and Composition of Bird Assemblages in Successional Atlantic Rain Forests

This study evaluated the influence of vegetation structure on bird diversity, guilds, and the richness and composition of species in different successional stages of the subtropical Atlantic rain forest. Much of the land that was formerly agricultural in the Brazilian Atlantic rain forest region is now given over to secondary forests. The habitat structure of these successional forests vary and are influenced by time, historical use and local variables, all of which affect bird assemblies. Sampling of bird species was carried out through audio-visual point counts conducted in forests varying from six years after abandonment to old-growth areas. Forests in which the point counts were conducted were further classified into initial, intermediate and advanced stages according to 11 vegetation structural variables, through cluster analyses. The study found that bird richness and diversity were similar between initial and intermediate stages, but higher in advanced areas. Bird species composition differed betwe...

Disentangling vegetation diversity from climate-energy and habitat heterogeneity for explaining animal geographic patterns.

Broad-scale animal diversity patterns have been traditionally explained by hypotheses focused on climate-energy and habitat heterogeneity, without considering the direct influence of vegetation structure and composition. However, integrating these factors when considering plant-animal correlates still poses a major challenge because plant communities are controlled by abiotic factors that may, at the same time, influence animal distributions. By testing whether the number and variation of plant community types in Europe explain country-level diversity in six animal groups, we propose a conceptual framework in which vegetation diversity represents a bridge between abiotic factors and animal diversity. We show that vegetation diversity explains variation in animal richness not accounted for by altitudinal range or potential evapotranspiration, being the best predictor for butterflies, beetles, and amphibians. Moreover, the dissimilarity of plant community types explains the highest proportion of variation in animal assemblages across the studied regions, an effect that outperforms the effect of climate and their shared contribution with pure spatial variation. Our results at the country level suggest that vegetation diversity, as estimated from broad-scale classifications of plant communities, may contribute to our understanding of animal richness and may be disentangled, at least to a degree, from climate-energy and abiotic habitat heterogeneity.

Modelling spectral reflectance of open cork oak woodland: a simulation analysis of the effects of vegetation structure and background

ABSTRACTThis study analyses the influence of vegetation structure (i.e. leaf area index and canopy cover) and seasonal background changes on moderate-resolution imaging spectrometer (MODIS)-simulated reflectance data in open woodland. Approximately monthly spectral reflectance and transmittance field measurements (May 2011 to October 2013) of cork oak tree leaves (Quercus suber) and of the herbaceous understorey were recorded in the region of Ribatejo, Portugal. The geometric-optical and radiative transfer (GORT) model was used to simulate MODIS response (red, near-infrared) and to calculate vegetation indices, investigating their response to changes in the structure of the overstorey vegetation and to seasonal changes in the understorey using scenarios corresponding to contrasting phenological status (dry season vs. wet season). The performance of normalized difference vegetation index (NDVI), soil-adjusted vegetation index (SAVI), and enhanced vegetation index (EVI) is discussed. Results showed that SAVI and EVI were very sensitive to the emergence of background vegetation in the wet season compared to NDVI and that shading effects lead to an opposing trend in the vegetation indices. The information provided by this research can be useful to improve our understanding of the temporal dynamic of vegetation, monitored by vegetation indices.

The influence of vegetation structure on spider species richness, diversity and community organization in the Apšuciems calcareous fen, Latvia

La influencia de la estructura de la vegetacion en la riqueza de especies, la diversidad y la organizacion de las comunidades de aranas en el pantano en terreno calcareo de Apsuciems, en Letonia Se considera que los pantanos en terrenos calcareos son uno de los ecosistemas mas amenazados de Europa. Asimismo, son uno de los habitats con mayor diversidad, puesto que albergan una variedad de especies de plantas y animales increiblemente rica y diversa. No obstante, a pesar de su diversidad, los pantanos en terrenos calcareos se han estudiado poco, especialmente por lo que hace a los invertebrados, como las aranas. Debido a que son buenos indicadores, es interesante conocer su ecologia en habitats singulares y amenazados. Este estudio tiene como finalidad documentar la composicion y diversidad de las especies, familias y gremios de alimentacion de aranas en los estratos edafico y herbaceo del pantano calcareo de Apsuciems, y evaluar la influencia de la estructura de la vegetacion en la organizacion de las comunidades de aranas. En verano de 2012, recogimos aranas que habitan en el suelo utilizando trampas de caida y aranas que habitan en la hierba con redes entomologicas. En total, en el pantano de Apsuciems se recogieron 2.937 aranas pertenecientes a 19 familias y 80 especies. Nuestros resultados indican que las especies y familias de aranas tienden a estratificarse a lo largo de la estructura vertical del habitat; la composicion de aranas en el estrato edafico diferia de la del estrato herbaceo. Por el contrario, la estructura de los gremios de alimentacion era parecida en el estrato edafico y el estrato herbaceo. Cada uno de los dos estratos estudiados presentaba gremios parecidos en proporciones similares. Nuestros resultados tambien pusieron de manifiesto que la composicion de aranas diferia considerablemente entre distintas partes del gremio y que gran parte de esta variabilidad se podia explicar por las propiedades arquitectonicas del habitat. En general, cuanto mas diversa era la vegetacion, mayor era el numero de aranas.

Germination of native and introduced plants from scats of Fallow Deer (Dama dama) and Eastern Grey Kangaroo (Macropus giganteus) in a south‐eastern Australian woodland landscape

SummaryIntroduced deer occur in many forests and woodlands in Australia and potentially play an important role in influencing the floristics and structure of these landscapes through eating plants and disseminating seeds. In a glasshouse trial, we tested whether field‐collected scats of Fallow Deer (Dama dama) contained viable plant seeds. Scats of deer obtained from a woodland study area in Kosciuszko National Park, New South Wales, produced seedlings from a range of native and introduced plant species. Forbs and herbs were dominant in these samples, confirming the grazing behaviour of deer at the time scats were collected. Samples of scats from Eastern Grey Kangaroos (Macropus giganteus), collected contemporaneously from the same sites as deer scats, also produced plant germinants. By volume, deer scats produced a greater diversity of plant germinants, including native and weed species, than did kangaroo scats. Although no weed species emanating from deer or kangaroo scats were of national significance, several species were of regional environmental significance, including Common Mullein (Verbascum thapsis), which was only found germinating out of deer scat, Stinkgrass (Eragrostis cilianensis) and Purpletop (Verbena bonariensis). In addition to dispersing viable seeds, Fallow Deer may also influence vegetation structure through their browsing. Further research is necessary to elucidate their respective role in dispersing native and introduced plants as well as any impacts that foraging behaviour might be having on woodland landscapes, to better inform management of the resident deer population.

Hydrogeological controls on post-fire moss recovery in peatlands

Summary Wildfire is the largest disturbance affecting boreal peatlands, however, little is known about the controls on post-fire peatland vegetation recovery. While small-scale variation in burn severity can reduce post-fire moss water availability, high water table (WT) positions following wildfire are also critical to enable the re-establishment of keystone peatland mosses ( i.e. Sphagnum ). Thus, post-fire moss water availability is also likely a function of landscape-scale controls on peatland WT dynamics, specifically, connectivity to groundwater flow systems ( i.e. hydrogeological setting). For this reason, we assessed the interacting controls of hydrogeological setting and burn severity on post-fire moss water availability in three burned, Sphagnum -dominated peatlands in Alberta’s Boreal Plains. At all sites, variation in burn severity resulted in a dichotomy between post-fire surface covers that: (1) exhibited low water availability, regardless of WT position, and had minimal ( i.e. lightly burned feather mosses and severely burned Sphagnum fuscum ) or (2) exhibited high water availability, depending on WT position, and had substantial (>50%) moss re-establishment ( i.e. lightly burned S. fuscum and where depth of burn was >0.05 m). Notably, hydrogeological setting influenced the spatial coverage of these post-fire surface covers by influencing pre-fire WTs and stand characteristics ( e.g. , shading). Because feather moss cover is controlled by tree shading, lightly burned feather mosses were ubiquitous (>25%) in drier peatlands (deeper pre-fire WTs) that were densely treed and had little connection to large groundwater flow systems. Moreover, hydrogeological setting also controlled post-fire WT positions, thereby affecting moss re-establishment in post-fire surface covers that were dependent on WT position ( e.g. , lightly burned S. fuscum ). Accordingly, higher recolonization rates were observed in a peatland located in a groundwater flow through system that had a shallow post-fire WT. Therefore, we argue that hydrogeological setting influences post-fire recovery in two ways: (1) by influencing vegetation structure prior to wildfire, thereby controlling the coverage of post-fire surface covers and (2) by influencing post-fire WT positions. These results suggest that post-fire moss recovery in peatlands isolated from groundwater flow systems may be particularly susceptible to droughts and future climate change.

A game of cat-and-mouse: microhabitat influences rodent foraging in recently burnt but not long unburnt shrublands

We investigated the influence of vegetation structure and fire history on the foraging behavior of small rodents (Notomys mitchellii, Pseudomys hermannsburgensis, and Mus musculus) by conducting giving-up density (GUD) experiments in recently burnt (9–13 years since last fire) and long unburnt shrublands (> 40 years), and open and sheltered microhabitats, in a semiarid region of Western Australia. We predicted that rodents would spend less time foraging in recently burnt shrublands and open microhabitat and that the influence of microhabitat would be weaker in long unburnt compared to more recently burnt vegetation. Our findings show that fire history and microhabitat structure influence the foraging behavior of the study species and that the influence of microhabitat varies between fire histories. GUDs were higher in long unburnt vegetation and in open microhabitats. There was a microhabitat effect in recently burnt vegetation, but not in long unburnt. Rodents foraged more in sheltered microhabitats probably because predator encounters are less likely to occur there and it provides them with greater refuge from predation. The presence of a microhabitat effect in recently burnt, but not long unburnt vegetation suggests that understory vegetation density is more important in mediating predation risk than canopy density. Future studies of small mammal responses to land management actions should include behavioral, as well as population-level responses to differing fire regimes.

Structure and diversity of phyllostomid bat assemblages on riparian corridors in a human-dominated tropical landscape.

Tropical forests around the world have been lost, mainly because of agricultural activities. Linear elements like riparian vegetation in fragmented tropical landscapes help maintain the native flora and fauna. Information about the role of riparian corridors as a reservoir of bat species, however, is scanty. We assessed the value of riparian corridors on the conservation of phyllostomid bat assemblage in an agricultural landscape of southern Mexico. For 2 years (2011–2013), mist-netting at ground level was carried out twice during the dry season (December to May) and twice during the wet season (June to November) in different habitats: (1) riparian corridors in mature forest, (2) riparian corridors in pasture, (3) continuous forest away from riparian vegetation, and (4) open pastures. Each habitat was replicated three times. To determine the influence of vegetation structure on bat assemblages, all trees (≥10 cm dbh) were sampled in all habitats. Overall, 1752 individuals belonging to 28 species of Phyllostomidae were captured with Sternodermatinae being the most rich and abundant subfamily. Riparian corridors in mature forest and pastures had the greatest species richness and shared 65% of all species. Open pastures had the lowest richness and abundance of bats with no Phyllostominae species recorded. Six of the 18 species recorded could be considered as habitat indicators. There was a positive relationship between bat species composition and tree basal area. Our findings suggest that contrary to our expectations, bats with generalist habits and naturally abundant could be useful detector taxa of habitat modification, rather than bats strongly associated with undisturbed forest. Also in human-dominated landscapes, the maintenance of habitat elements such as large trees in riparian corridors can serve as reservoirs for bat species, especially for those that are strongly associated with undisturbed forest.

城市公园植被特征对陆生鸟类集团的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 城市公园植被特征对陆生鸟类集团的影响 DOI: 10.5846/stxb201311042667 作者: 作者单位: 华东师范大学;上海市城市化过程与恢复重点实验室,华东师范大学;上海市城市化过程与恢复重点实验室,华东师范大学;上海市城市化过程与恢复重点实验室,华东师范大学;上海市城市化过程与恢复重点实验室,上海市野生动植物保护管理站,上海市野生动植物保护管理站,上海市野生动植物保护管理站,上海科技馆,华东师范大学;上海市城市化过程与恢复重点实验室 作者简介: 通讯作者: 中图分类号: 基金项目: 上海市绿化和市容管理局专项基金; 浦东新区科技发展基金(PKJ2011-N020); 上海市城市化生态过程与生态恢复重点实验室开放课题基金 The influence of vegetation structure on bird guilds in an urban park Author: Affiliation: East China Normal University,,,,,,,,East China Normal University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:城市公共绿地是城市生态系统中重要的鸟类栖息地,其植被特征对鸟类集团存在显著影响。在通过分析植被特征对陆生鸟类集团的作用,从而为公园合理配置植被来提高其作为野生动物栖息地的生态服务功能提供理论基础。2009 年10 月至2011 年10 月,采用样线法对上海滨江森林公园进行鸟类调查,利用主成分分析划分鸟类集团,用高度定义植被层次,用卡方检验分析鸟类行为在植被层次上的差异。结果表明,滨江森林公园陆生鸟类群落在乔木层的栖息行为和运动行为频次显著多于其在灌木层和地被层的行为频次,在地被层的取食行为频次显著多于其在乔木层和灌木层的行为频次。陆生鸟类可划分为8 个鸟类集团,鸟类集团之间存在栖息、运动和取食空间生态位的重叠。食虫拾取集团、杂食拾取集团、食肉飞取集团和植食拾取集团在栖息、运动和取食空间生态位上均存在较高的重叠度,其通过食性分离各自空间生态位。食虫探取集团和食虫飞取集团互为栖息空间生态位重叠度最高集团,其通过取食方式的不同来实现生态位的分离。根据公园植被特征对鸟类集团的影响结果对上海市公园绿地植被配置提出了建议。 Abstract:The acceleration of urbanization has led to a loss of biodiversity, which is a global ecological problem of great concern. Meanwhile, birds are useful indicators in monitoring environmental changes in urban ecosystem. Urban green areas have always been paid great attention because of their functions as natural habitats for many wildlife species. Bird guilds are groups of species that use environmental resources in similar ways. Therefore, we analyze the function of vegetation structure to bird community and bird guilds so that we make suggestions related to the design of urban green spaces in Shanghai. From October 2009 to October 2011, we set the line transect to survey the bird community in Shanghai Binjing Forest Park. According to the height of plant, we divided the habitat vegetation into three vertical levels including tree layer, shrub layer and ground layer. Chi-square test showed that there were significant differences among behaviors in three vegetation layers. The frequency of perching and moving in tree layer was more significant than that in other two layers and the frequency of feeding in ground layer was more significant than that in other two layers. According to the variables based on the location, feeding habits and foraging behavior pattern of birds, we classified 8 bird guilds including herbivorous collecting, herbivorous pecking, insectivorous collecting, insectivorous flying catching, insectivorous pecking, omnivorous collecting, omnivorous pecking and raptorial flying catching. There were differences and overlaps among the frequency of three behaviors of 8 bird guilds in three layers, so we considered there was niche overlap among 8 bird guilds. According to Morisita-Horn Index, the results indicated that insectivorous collecting guild, omnivorous collecting guild, flying catching guild and herbivorous collecting guild had high niche overlap of perching, and moving and feeding so these guilds reached niche separation by their diets. Insectivorous pecking guild and insectivorous flying catching guild had the most perching niche overlap with each other, and they reached niche separation by their foraging behavior patterns. Based on the results above, we concluded that trees were one of the most important vegetation components that enhance the bird species richness and diversity in urban green spaces because they provide roosting, nesting, hiding, and foraging sites. The shield function of shrub cover was confirmed to be an important habitat component and the ground layer provided food resources to bird community. The suggestion and recommendation in construction of urban parks was presented based on this study. The density and coverage of shrub layer should improve and large area of artificial lawn should be divided into several small pieces. We also discuss the conflicts between habitat for biodiversity maintenance and recreational function in urban parks. 参考文献 相似文献 引证文献

Does habitat heterogeneity in a multi-use landscape influence survival rates and density of a native mesocarnivore?

The relationships between predators, prey, and habitat have long been of interest to applied and basic ecologists. As a native Great Plains mesocarnivore of North America, swift foxes (Vulpes velox) depended on the historic disturbance regime to maintain open grassland habitat. With a decline in native grasslands and subsequent impacts to prairie specialists, notably the swift fox, understanding the influence of habitat on native predators is paramount to future management efforts. From 2001 to 2004, we investigated the influence of vegetation structure on swift fox population ecology (survival and density) on and around the Piñon Canyon Maneuver Site, southeastern Colorado, USA. We monitored 109 foxes on 6 study sites exposed to 3 different disturbance regimes (military training, grazing, unused). On each site we evaluated vegetation structure based on shrub density, basal coverage, vegetation height, and litter. Across all sites, annual fox survival rates ranged from 0.50 to 0.92 for adults and 0.27 to 0.78 for juveniles. Among sites, population estimates ranged from 1 to 7 foxes per 10 km transect. Fox density or survival was not related to the relative abundance of prey. A robust model estimating fox population size and incorporating both shrub density and percent basal cover as explanatory variables far outperformed all other models. Our results supported the idea that, in our region, swift foxes were shortgrass prairie specialists and also indicated a relationship between habitat quality and landscape heterogeneity. We suggest the regulation of swift fox populations may be based on habitat quality through landscape-mediated survival, and managers may effectively use disturbance regimes to create or maintain habitat for this native mesocarnivore.

A Comparison of Foraging Site Characteristics of Two African Resident Insectivorous Birds in a Burned Habitat

Detailed investigation of the foraging site utilised by avian species may reveal the habitat factors important in their conservation. This study compared the foraging sites of the Sunlark, Galerida modesta and Familiar Chart, Cercomela familiaris (both African resident insectivorous birds) a week after fire engulfed about one third of the 300 ha of the Amurum Forest Reserve, Nigeria. Foraging sites were compared based on proxies of food availability (ant, grasshopper and other insect abundance) and vegetation structure. Data on food availability and vegetation structures were obtained by quadrate sampling while foraging spots were determined from four stratified transects each surveyed four times during the study. Food availability was not a significant predictor of foraging site characteristics between the two bird species. However of the nine vegetation variables measured, grass height and proportion of burned grass cover per foraging site significantly distinguished the foraging sites of the two bird species; Sunlark foraged more at sites with shorter grasses and high proportion of burned grass cover as compared to the Familiar Chat. The characteristics of the foraging sites observed might have implications on the foraging success of the birds in line with literature on the Influences of vegetation structure on avian foraging behaviour. Key words: Foraging site, Insectivorous birds, Burn, Vegetation structure, Food availability

Winter Bird Habitat Use in a Heterogeneous Tallgrass Prairie

In the Flint Hills of Kansas and Oklahoma, U.S.A., grazing land is managed predominantly to promote homogeneous grassland structure. This potentially limits the diversity of habitats for grassland obligate songbirds with narrow habitat preferences during the breeding season, prompting ecologists and conservationists to call for managing rangelands for increased heterogeneity. The Flint Hills also hosts multiple species of conservation concern during winter, but avian habitat requirements are less well known during this period and seldom considered in management recommendations. We investigated the influence of vegetation structure on occurrence of songbirds overwintering at The Nature Conservancy's Tallgrass Prairie Preserve in Osage County, Oklahoma, where fire and grazing are used to increase structural and compositional heterogeneity. During the winters of 2008–2009 and 2009–2010, we used an area-search method to survey 149, 1 ha plots distributed among patches that represented a wide gradient in vegetation structure and 1–3 growing seasons since fire. We modeled occurrence of Le Conte's Sparrow (Ammodramus leconteii), Sedge Wren (Cistothorus platensis), Savannah Sparrow (Passerculus sandwichensis), and Smith's Longspur (Calcarius pictus) with a combination of fine-scale vegetation (e.g., litter depth in sampling plots), landscape-scale factors (e.g., distance to utility poles), and time since fire. Vegetation height was the most consistent predictor for three species, with Le Conte's Sparrow and Sedge Wren associated with tall structure and Smith's Longspur associated with shorter structure. Occurrence of Smith's Longspur was too low to adequately model effects of burn age, but fine-scale vegetation structure used by Le Conte's Sparrow and Sedge Wren was available in plots irrespective of time since fire. A variety of management techniques for creating habitat heterogeneity have the potential to promote grassland songbird diversity during winter, but further study is needed.

Experimental removal of woody vegetation does not increase nesting success or fledgling production in two grassland sparrows (Ammodramus) in Pennsylvania

The influence of vegetation structure on the probability of daily nest survival (DNS) for grassland passerines has received considerable attention. Some correlative studies suggest that the presence of woody vegetation lowers DNS. Over 3 years (2009–2011), we monitored 215 nests of the Grasshopper Sparrow (Ammodramus savannarum) and Henslow's Sparrow (A. henslowii) on 162 ha of reclaimed surface-mine grasslands in Pennsylvania. We removed shrubs from treatment plots with ≤36% areal coverage of woody vegetation in a before-after-control-impact-pairs (BACIP) design framework. Daily nest survival (95% CI: 0.94–0.96) was as high as previous studies have reported but was not associated with woody vegetative cover, proximity to woody vegetation, or woody stem density. Variation in DNS was best explained by increasing nonwoody-vegetation height. Grasshopper Sparrow fledgling production on treatment plots in 2010 (95% CI: 3.3–4.7) and 2011 (95% CI: 3.8–5.0) was similar to baseline conditions of treatment plots (95% CI: 3.4–4.9) and control plots (95% CI: 3.2–4.5) in 2009. Fledgling production was associated with thatch depth (β ± SE = 0.13 ± 0.09) and bare ground (β ± SE = -2.62 ± 1.29) adjacent to the nest and plot woody vegetative cover ( ± SE = -3.09 ± 1.02). Our experimental research suggests that overall reproductive success of Grasshopper and Henslow's sparrows on reclaimed surfacemine grasslands is driven by a suite of largely nonwoody—vegetation components, and both species can successfully nest and produce young in habitats with greater amounts of scattered woody vegetation than has generally been considered.

Implications of shifts in coffee production on tree species richness, composition and structure on small farms around Mount Kenya

Small coffee farms around Mount Kenya in Kenya contain many planted and remnant tree species but little is known in the region about the relationship between trees on farms and the methods and dynamics of coffee production. Shifts in production may alter tree diversity and potentially impact on future biodiversity conservation efforts by affecting niches available for indigenous trees on farms. Here, knowledge was gathered on how changes in coffee production on 180 small farms around Mount Kenya may affect tree diversity, categorizing farms according to coffee yield levels over a period of five years as increasing, decreasing or stable production. Tree species richness, abundance and composition were analyzed using species accumulation curves, Renyi diversity profiles, rank abundance and ecological distance ordinations, and the effects of coffee production examined using quasi-Poisson generalized linear regressions. Species richness were positively correlated with tree basal area but negatively related to coffee, banana and maize yields value. A difference in average tree species richness, abundance and basal area on increasing farms was observed compared to the decreasing and stable farms, even though formal tests on richness and densities differences were inconclusive. These dynamics do not significantly influence vegetation structure but seem to have a bearing on species composition on farms of different coffee production. The overall low abundance (23 % of trees) but high richness (78 % of species) of indigenous trees on coffee farms could change markedly if the dynamics observed in the current study persist, indicating the need for the development of intensified multi-species cropping systems.