Habitat preferences of Helmeted Guineafowl Numida meleagris in the Krugersdorp Game Reserve,Gauteng province,South Africa

Field surveys were conducted in the Krugersdorp Game Reserve, Gauteng province, South Africa, during 1978–1981 to study the habitat preferences of Helmeted Guineafowl Numida meleagris. The study area was traversed with a vehicle in the late afternoons on a set route (12 km) and at least one observation was conducted each month during the three-year period. With the aid of binoculars all guineafowl that were sighted were counted and recorded on a map. The purposes were to (1) describe the habitat preferences of guineafowl and (2) to demonstrate that weeds attracted guineafowl during winter and can be retained in modified landscapes (e.g. farms) to provide important microhabitats. The highest mean monthly density across five habitat categories throughout the year was recorded in old vegetable gardens. The old vegetable gardens of c. 35 ha attracted more than 60% of the guineafowl population from April to October, which was mainly during winter when the birds scratched actively in weedy patches.     

The effects of agriculture on farmland bird assemblages on the Agulhas Plain, Western Cape, South Africa

Coastal Fynbos on the Agulhas Plain of the Western Cape, South Africa, has been transformed extensively by crop and pastoral agriculture. Many bird species, e.g. sunbirds, nightjars and mousebirds have consequently been affected negatively by the reduction of suitable habitat for daily requirements. However, populations of certain bird species, especially granivores and omnivores, such as sparrows, larks and pipits, as well as Egyptian Geese and Helmeted Guineafowl have proliferated on the Agulhas Plain. This study investigates the effects of agricultural development on overall bird diversity on the Agulhas Plain. In 1998, twice monthly transect counts at 13 farmland sites recorded 106 bird species. Fifteen species occurred at 75% or more of the sites. Highest avian diversity was recorded at the sites with a mixture of crops and Coastal Fynbos (Mixed regime). A small number of species, e.g. sunbirds, are reliant on the natural Coastal Fynbos for their survival. With the exception of the Mixed regime that gained 50 species, all the other agricultural regimes reflected a loss of diversity when compared with Fynbos. To provide more suitable habitat for a greater diversity of birds, mixed landscapes should be maintained, and further destruction of natural Fynbos habitat should be prevented.     

Waterbird assemblages and associated habitat characteristics of farm ponds in the Western Cape, South Africa

Natural freshwater wetlands are among the most threatened habitats on Earth. Effective wetland biodiversity conservation can not, however, be evaluated without fully understanding the roles of artificial waterbodies as refuges for water-dependent plants and animals. Waterbird assemblages were examined on 59 farm ponds in the Elgin and Caledon districts of the Western Cape, South Africa. This study examines the relationship between waterbird use and habitat characteristics of farm ponds. Patterns of temporal and spatial variation of waterbird species richness and abundance were quantified in relation to the habitat characteristics of each pond. Cluster analysis and multiple regression analyses identified surface area of the farm ponds as an important variable determining the presence and abundance of many waterbird species. Structural diversity in terms of vegetation in and around the ponds was especially important in determining their usage by waterbirds. These variables were evaluated in terms of creating a mosaic of habitat types (by varying vegetation structure and pond topography), which may be a useful way to enhance waterbird diversity at farm ponds. This study concludes that the high number of farm ponds in the transformed habitat matrix of the Western Cape plays an important role in conserving waterbirds.     

长江师范学院校园夏季鸟类群落与多样性分析

2008年3～7月采用样线法对长江师范学院李渡校园鸟类组成和种群数量进行了调查,共记录鸟类6目21科28种,数量1633只,物种多样性指数为3．9204,均匀性指数为1．1765,其中国家“三有”名录鸟类25种,CITES名录鸟类1种。鸟类区系以东洋界成分为主。对不同生境鸟类多样性的分析结果表明：（1）乔灌林鸟类多样性指数和均匀性指数最高,水域鸟类多样性指数最低,建筑区均匀性指数最低;（2）乔灌林与竹林的相似性指数最高,竹林与水域的相似性最低。     

Contrasting effects of habitat fragmentation,population density,and prey availability on body condition of two orb‐weaving spiders

1. Habitat fragmentation is a major threat to biodiversity because it disrupts movement between habitat patches. In addition, arthropod fitness may be reduced in fragmented habitats, e.g. due to reduced prey availability. 2. We studied the relationship of spider body condition with habitat fragmentation, population density, and prey availability. We expected that prey availability and population density of spiders would be affected by landscape composition and patch isolation. Body condition should be enhanced by high prey availability, but negatively affected by population density due to competition. 3. We sampled spiders on 30 groups of cherry trees that varied independently in the level of isolation from other woody habitats and in the percentage of woody habitat within 500 m radius. As a measure of body condition, we used residuals of the relationship between individual body mass/opisthosoma width and prosoma width of the two most common orb‐weaving spider species, Nuctenea umbratica Clerck and Araniella opisthographa Kulczynski. 4. Body condition of A. opisthographa was positively correlated with the abundance of flies, which increased with the percentage of forest in the landscape. In contrast, body condition of N. umbratica was reduced at high population densities, presumably due to intraspecific competition. In addition, body condition and population density of A. opisthographa was lower at isolated sites. 5. Our study suggests that effects of landscape fragmentation on body condition vary strongly between spider species, depending on the relative role of food limitation and intraspecific competition.     

The influence of landscape structure on occurrence, abundance and genetic diversity of the common frog, Rana temporaria

Human‐caused habitat destruction and modification constitute one of the largest threats to population persistence and biodiversity, and are also suspected to be the major cause behind the global decline of amphibian populations. We assessed the potential role of agriculture‐related habitat fragmentation on population size and genetic variability in the common frog (Rana temporaria) by recording the occurrence, population density and genetic diversity in three geographically disparate regions in Sweden – each containing landscapes of high and low agricultural activity – and related these to landscape variables extracted from digital maps. We found a highly significant region‐by‐landscape interaction in occurrence, population density and genetic diversity revealing a reversed response to agriculture from south to north: while the effects of agriculture on R. temporaria populations were negative in the south, there were no effects in the central region, whereas positive effects were observed in the north. Spatial autocorrelation analyses of genetic data revealed that populations in high agricultural activity areas were more isolated than populations in low activity areas both in the southern and central regions of Sweden. Landscape diversity showed a strong positive correlation with both density and occurrence of frogs in Sweden as a whole, as well as in the southern region. Also, negative effects of roads and positive effects of ditches on genetic diversity were found in the south. Overall, these results suggest clear but regionally opposite effects of habitat structure on the population size and genetic diversity of amphibian populations. This means that the management strategy aiming to maximize the size and genetic diversity of local common frog populations, and perhaps also those of other amphibian populations, should account for regional differences in existing land‐use patterns.     

Patterns of bird abundance and habitat use in rice fields of the Kanto Plain, central Japan

Rice fields, the most widespread cropland in Japan, provide important habitat for birds, but few studies have examined bird communities that are influenced by agriculture in rice fields. I studied the seasonal pattern of bird abundance and their habitat preferences in terms of agricultural habitats in the rice fields of the central Kanto Plain, central Japan. In total, 19 waterbird species and 31 landbird species were recorded over the study year. Waterbird occurrence was largely restricted to the cultivation season (i.e. the flooded season, May–August), with maximum abundance in August. Rice fields dried up during winter and supported few waterbirds except for irregular occurrences of little egrets (Egretta garzetta) and common snipes (Gallinago gallinago), which selectively used ditches with shallow water. Landbird abundance increased after the start of cultivation (May) to August, but more birds were attracted to the rice fields in midwinter (around January). For both waterbirds and landbirds, most species preferred levees and fallow grass fields, but avoided fields with rice vegetation. Unplowed fields after harvest were preferred by several species including skylarks (Alauda arvensis), while plowed fields were less attractive to most species. These results suggest the need for advanced agricultural practices to include improvement in habitat quality for birds.     

Influences of habitat complexity on the diversity and abundance of epiphytic invertebrates on plants

SUMMARY 1. The compound influence of habitat complexity and patch size on stream invertebrate assemblages associated with submerged macrophytes was investigated through field sampling of two natural macrophyte species with contrasting leaf morphologies (complex, Ranunculus yezoensis; simple, Sparganium emersum) and an experiment with two artificial plants with different levels of morphological complexity. 2. The artificial plant experiment was designed to separate the effects of habitat area (patch size) and habitat complexity, thus enabling a more rigorous assessment of complexity per se than in previous studies where only a single patch size was used. Simple and complex artificial plants were established with five different patch sizes corresponding to the range found in natural plants. 3. Invertebrates occurred on both complex and simple forms of natural and artificial plants at similar abundances with dipterans and ephemeropterans being predominant. Taxon richness was higher on structurally complex Ranunculus than on simple Sparganium and was similarly higher on the complex artificial plant than on the simple one, over the entire range of habitat patch sizes. Thus, architectural complexity affected the taxon richness of epiphytic invertebrates, independently of habitat scale. 4. On the natural plants there was no difference in the abundance (both number of individuals and biomass) of invertebrates between simple and complex forms, while on artificial plants more invertebrates occurred on complex than on simple forms. The amount of particulate organic matter, >225 μm (POM) and chlorophyll a showed mixed patterns on natural and artificial plants, suggesting that the availability of these resources is not an overriding proximate factor controlling invertebrate abundance on plants. The difficulty of extrapolating from experimental results involving use of artificial plants is discussed, especially when considering the relationship between habitat structure and the occurrence of epiphytic invertebrates on natural plants.     

Ecological integrity assessment of the fish assemblages of the Matigulu/Nyoni and Umvoti estuaries,KwaZulu-Natal,South Africa

The estuarine fish community index (EFCI) and an estuarine fish guild assessment (EFGA) were used in 2004 and 2008 to determine the ecological state and effects of selected ecosystem variables on the Umvoti and Matigulu/Nyoni estuaries. The EFCI indicated that the Matigulu/Nyoni Estuary was in a moderate state and that the Umvoti Estuary was in a poor to very poor state. The EFGA revealed a clear spatial differentiation, based on the estuaries’ fish community structures, that was being driven primarily by the freshwater-dominated state of the Umvoti Estuary and the poor water quality of the Umvoti Estuary. The analysis of estuarine fish assemblage characteristics was shown to contribute towards the management and conservation of these systems.     

The relationship between local and regional diversity of indigenous forest fauna in KwaZulu-Natal Province, South Africa

The relationship between local and regional diversity was tested by regressing local community richness against regional species diversity for three taxa, birds, butterflies and mammals, in subtropical forest. The quadratic model best fits the relationship between local and regional diversity for birds. Local bird species richness is theoretically independent of the size of the regional pool of species and may represent saturated communities. A linear model best describes the relationship for mammals and butterflies. For mammals, the slope is shallow (0.264) and regional richness overestimates local species richness, suggesting communities are undersaturated. Extinction filtering may explain this pattern. Past climatic changes have filtered out many mammalian species, these changes have been too recent for autochthanous speciation, and the relatively low vagility of mammals has prevented extensive recolonisation. Differences in the nature of the diversity relationship between taxa are as much due to independent evolutionary histories as to differences in vagility and colonising potential. A pervasive role is suggested for regional biogeographic processes in the development of faunal assemblage structure. Large-scale processes are not considered in current conservation plans. We encourage the shift of conservation emphasis from local ecological processes and species interactions, to whole communities and consideration of regional processes.     

The effects of development on forest-patch characteristics and bird diversity in Suji,South Korea

In a forested area located in the Suji District of Yongin City, Gyunggi Province, South Korea, the relationship between development and forest-patch characteristics and that between development and bird biodiversity were observed and analyzed. As four development projects progressed over a 13-year period (1990–2003), Landsat images showed how a continuous forest was reduced and fragmented and how isolated forests either shrank or disappeared. The ratio of the edge area to the forested area changed also and reflected the stages of the four development projects. A single continuous forest patch was studied, and it showed fragmentation and a reduction in size over time associated with the development projects. The effect of the later developments on adjacent forested areas was much greater than the effect of the initial development. As expected, the initial development affected the forested area near the initial development, but the later developments also significantly affected the same area near the initial development. Bird population characteristics—numbers of individuals and species (biodiversity)—were analyzed using field observations at nine sites in both continuous and isolated forest areas. A gradient of decreasing bird species and the number of individuals was established by an analysis of observations made in the interior, intermediate, and edge areas of the continuous forest. Whereas both the isolated forest and the interior areas of the continuous forest studied had similar numbers of individual birds, the isolated forest areas and the edge areas of the continuous forest showed significantly lower biodiversity than the interior areas studied. The results show that developments cause not only the forest loss, fragmentation, and expansion of the edge area but also a lowering of bird diversity; especially, the later developments have been under more pressure to develop the surrounding area. Therefore, it is necessary to manage the edge area, which is vulnerable to development, to minimize the effects of development.     

Impact of rapid urbanization on the floral diversity and agriculture land of district Dir,Pakistan

In the World urbanization is a serious problem especially in developing countries which creates serious environmental problems like climatic and ecological changes in the ecosystem. The present paper aims to explain urbanization that causes loss of agriculture lands, biodiversity, soil erosions and grazing in District Dir. Urbanization decreased species richness such as Salix alba and Populus alba in the last few years in the local area. Soil of local area was divided into three different zones and was tested for soil texture and mineral percentage. Zone I soil showed sandy loamy texture with a pH of 8.3, Nitrogen 0.012%, Phosphorus 5.0% and organic matter was 0.74 (ppm). Zone II soil was loamy sand in texture with pH 8.1, Nitrogen 0.011%, Phosphorus 6.2%, and organic matter was 0.24 (ppm) while Zone III soil texture was silty clay loam with a pH of 8.1, Nitrogen 0.032%, Phosphorus 11.3%, and organic matter was 0.60 (ppm). The current work concludes that urbanizations affect natural biodiversity and agriculture lands, and that soil erosion and watering-points trampled by livestock is one of the significant problems in district Dir, and that the main degrading factor is the overexploitation of vegetation for fuel-wood and livestock grazing.     

Impact of land use on vegetation composition, diversity, and selected soil properties of wetlands in the southern Drakensberg mountains, South Africa

Wetlands provide the ecosystem services of enhancing water quality, attenuating floods, sequestrating carbon and supporting biodiversity. In southern Africa, the pattern and intensity of land use is influenced by whether land tenure is public (state), private (individual ownership), or communal (shared agricultural and grazing resources). The influence of land tenure and its associated use on service provision was compared for communal tenure (grazing, maize production), wildlife conservation, and commercial agriculture (grazing, planted pastures) in the southern Drakensberg. Ordination analyses revealed that oxbow marshes, hill slope seepages and hygrophilous grasslands, the main hydro-geomorphic units, supported distinct plant communities that differed in their response to land use because of wetness or slope. Oxbows, uncultivated because of wetness, were inherently species poor with few exotics. Composition of hill slope seepages, uncultivated because of saturated slopes, varied among tenure types most likely in relation to grazing pressure. Seepages were threatened by the exotic invasive Rubus cuneifolius. Eighty-five percent of hygrophilous grassland had been cultivated by 1953, most of which was subsequently abandoned to secondary grassland. Primary hygrophilous grassland and hill slope seepages were the main repository for indigenous plant diversity, while communal maize fields supported a diverse mixture of mainly exotic species. Soil carbon concentrations decreased from oxbows to pastures, seepages, primary hygrophilous grassland, secondary grassland, and maize on former grassland (7.0, 4.1, 4.0, 3.5, 2.4, and 1.7%, respectively). The pattern for total soil nitrogen and sulphur were the same. Cultivation of hygrophilous grassland was estimated to have reduced soil carbon stocks to 69% of pre-settlement levels by 1953 (∼150 years BP). Stocks then increased by 8% to 2001 following crop abandonment. Cultivation has impaired water quality enhancement and flood attenuation because of greater amounts of bare ground and shorter vegetation. Further improvement of ecosystem services will depend on the influence of socio-economic factors on communal cropping.     

A fence-line contrast reveals effects of heavy grazing on plant diversity and community composition in Namaqualand,South Africa

Changes in plant species richness and community composition were investigated across a fence separating heavily grazed communal and lightly grazed commercial farming systems in Namaqualand, South Africa. No significant differences in plant species richness between communal and commercial farming systems were detected either locally within individual plots or overall across all plots. Within-plot, richness of species tolerant of grazing, such as annuals and geophytes, has increased, while the richness of large palatable shrub species has decreased on the communal rangeland. In terms of plant cover, species' responses to grazing were strongly associated with growth form. Annuals and geophytes formed the majority of grazing increasers, while large, presumably palatable, shrubs and leaf succulents were characteristic grazing decreasers. An investigation into population processes of five shrub species revealed that heavy grazing on the communal rangeland has resulted in: reduced size of palatable shrub species; reduced flower production and seedling recruitment of palatable species; increased density and recruitment of the unpalatable shrub, Galenia africana. Reductions in shrub volume, reproductive output and seedling recruitment were most marked in the palatable shrub Osteospermum sinuatum and were in the order of 90%. The results are further discussed in terms of their relevance to rangeland dynamics and the current land use practices of the region.     

Habitat utilization and home range of the redwing francolin, Francolinus levaillantii, in highland grasslands, Mpumalanga province, South Africa

The effects of intensive commercial livestock farming on the distribution and habitat use of the redwing francolin, Francolinus levaillantii, was investigated to identify habitat constraints that may contribute towards the observed decline of this species on livestock farms. Data on the size, placement of the home ranges and compositional habitat use from ten radio‐tracked individuals, five in commercially grazed (and frequently burned) and five in protected (and infrequently burned) highland grasslands, was collated to determine habitat preferences. Mean home range size within protected and grazed grassland study sites were similar and ranged between 7.6 and 15.4 hectares. However, habitat use by groups in grazed grasslands was restricted to areas of greater cover and food availability. Group sizes were significantly larger in protected (mean 3.77, n = 111 coveys) than in grazed and frequently burned grassland (mean = 2.96, n = 135 coveys). Smaller coveys in grazed habitats had smaller home ranges and were further spaced from one another. It is therefore suggested that habitat degradation, through excessive defoliation of the grassland from heavy grazing and frequent burning, both fragments francolin subpopulations and reduces the ecological availability of suitable habitat. Thus, undermining the metapopulation structure of the redwing francolin in these commercially grazed grasslands.     

Landscape genetics of the self-compatible forest herb Geum urbanum: effects of habitat age, fragmentation and local environment

To investigate the role of habitat fragmentation, fragment age and local environment in shaping the genetics of plant populations, we examined the genetic structure of the self-compatible forest herb Geum urbanum using microsatellite markers. A historical land-use reconstruction assigned the studied populations to two age classes: populations in primary forest fragments, and populations in secondary fragments. Local environmental conditions were quantified on the basis of the herb-layer community composition. A stepwise general linear model revealed that levels of within-population genetic diversity were best explained by population size, landscape connectivity and the interaction between both. Connectivity was positively correlated with the genetic diversity of small populations, but did not significantly affect the diversity of large populations. Contrary to what we expected, secondary-forest populations showed lower divergence relative to populations located in primary patches. Small populations were genetically more diverged compared to large populations. Mantel tests showed no significant isolation by distance and no significant correlation between habitat similarity and genetic differentiation. We conclude that gene flow has probably prevented founder events from being reflected in the present genetic structure of G. urbanum. Gene flow towards low-connectivity populations, however, seemed to be insufficient to counteract the effects of drift in small populations.     

Experimental simulations about the effects of overexploitation and habitat fragmentation on populations facing environmental warming

Populations of many species are dramatically declining worldwide, but the causal mechanism remains debated among different human-related threats. Coping with this uncertainty is critical to several issues about the conservation and future of biodiversity, but remains challenging due to difficulties associated with the experimental manipulation and/or isolation of the effects of such threats under field conditions. Using controlled microcosm populations, we quantified the individual and combined effects of environmental warming, overexploitation and habitat fragmentation on population persistence. Individually, each of these threats produced similar and significant population declines, which were accelerated to different degrees depending upon particular interactions. The interaction between habitat fragmentation and harvesting generated an additive decline in population size. However, both of these threats reduced population resistance causing synergistic declines in populations also facing environmental warming. Declines in population size were up to 50 times faster when all threats acted together. These results indicate that species may be facing risks of extinction higher than those anticipated from single threat analyses and suggest that all threats should be mitigated simultaneously, if current biodiversity declines are to be reversed.