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The influence of riparian vegetation on the distribution and abundance of bats in an African savanna

100%

Monadjem A. , Reside A.

nr 2

Riparian habitats are known to be important for bats across the world, however this is largely unstudied in Africa. We investigated the community structure of bats in riparian areas and the surrounding savanna landscape in Swaziland's lowveld using mist nets and a harp trap. We found riparian sites overall had higher bat activity, diversity, species richness and abundance. One species (Epomophorus wahlbergi) accounted for 52.6% of captures. Seasonality had no effect on overall captures, nor did distance from nearest riparian habitat for savanna sites. Echolocation guilds were correlated with vegetation characteristics, with CF (constant frequency), FM (steep frequency-modulated) and FM-QCF (broadband FM) bats more frequently captured at sites with denser undergrowth than QCF (quasi-constant frequency or narrowband FM) bats; conversely, QCF bats were more frequently caught at sites with lower canopy cover than other bats. Our findings suggest that although bats discriminate between microhabitats, they do not respond to larger-scale habitat features in the way that other taxa, such as birds, are found to. In conclusion it appears that riparian areas are important foraging sites for bats within African savannas.

Do trees make a difference? An evaluation of the impact of riparian vegetation on the ecology of nutrient poor headwater streams

84%

O'Driscoll J. F. , Harrison S. S. C. , Giller P. S.

tom 54

nr 4

The presence of riparian vegetation is shown to affect both physical and biological properties of headwater streams. Riparian vegetation mediates food resource availability for macroinvertebrates and fish within streams through addition of allochthonous material such as leaves, woody debris and terrestrial invertebrates. Riparian shade can also reduce biomass and production of autochthonous algae. The potential role of riparian vegetation in enhancing biodiversity and productivity of headwater streams is discussed, with reference to improving salmonid fish stocks in the headwater streams of Ireland and Great Britain.

Aquatic habitat inventories using remote sensing

84%

Armantrout N. B.

nr 1-2

Increasing emphasis is being placed on managing aquatic resources on an integrated, basinwide basis. Traditional ground inventory methods are time-consuming and expensive, and are not easy to integrate over large areas. Remote sensing, combined with Geographic Information Systems (GIS) and Geographic Positioning System (GPS) technology, offers a more flexible, cost-effective method for gathering and integrating information. Digital terrain models, spectral separations, and microwaves can be used to define physical and biological features. Habitat conditions in a basin can be defined by four basic elements: climate, geomorphology, vegetation and human activities. All of these can, to different degrees, be directly inventoried by remote sensing. When used with GPS and GIS systems, remote sensing information can be merged with field data and other sources of information to create an integrated summary of resource conditions. Information can be summarized on a range of scales, from local to region-wide, and can be compared over time as a monitoring and evaluation tool.

Riparian vegetation of streams and the macroinvertebrate community structure

67%

Bis B. , Higler L. W. G.

nr 1-2

Riparian vegetation is a typical ecotone by its structural and functional position between the terrestial part of the watershed and the stream (Naiman, Decamps 1990). In consequence, the riparian zone forming an integrated component of stream ecosystems significantly determines the aquatic community. Macroinvertebrates are affected by defined variability of environmental factors. In streams under canopy: light access is reduced; summer temperatures are lower; shed leaves form the main source of energy; insects falling from the vegetation into the water create another source of food; roots from trees form shelter and strongly influence hydraulic patterns. As a result, many (micro) habitats can exist and persist. The relationships between the covered percentage of the riparian zone, hydraulic processes, POM retention and macroinvertebrate functional organization was analyzed. Riparian vegetation forms a buffer zone in agricultural landscape and thus prevents inflow of nutrients, but also of fine sediments. Clearing of riparian vegetation changes all these conditions, resulting in a totally different and less varied biocommunity. Examples are given from Poland and The Netherlands.