Individual study: Wetland creation in agricultural landscapes: Biodiversity benefits on local and regional scales
Thiere G., Milenkowski S., Lindgren P.E., Sahlen G., Berglund O. & Weisner S.E.B. (2009) Wetland creation in agricultural landscapes: Biodiversity benefits on local and regional scales. Biological Conservation, 142, 964-973
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Create scrapes and pools
A site comparison study of 36 newly created dual-purpose wetlands on agricultural land in Sweden (Thiere et al. 2009) found that wetland creation increased aquatic macroinvertebrate diversity in agricultural landscapes. Wetlands had between 6-51 aquatic macroinvertebrates (total 176). Flight-dispersed insects dominated macroinvertebrate species richness: beetles (Coleoptera): 6, dragonflies and damselflies (Odonata): 4, caddisflies (Trichoptera): 5, true bugs (Heteroptera): 5, flies (Diptera): 4, mayflies (Ephemeroptera): 3, slugs and snails (Gastropoda): 2, butterflies and moths (Lepidoptera): 1, leeches (Hirudinea): 1, others: 3. The estimated gain per created wetland ranged from 1 to 33 species. Sub-regions with high wetland density had higher species diversity and accumulation, but not different macroinvertebrate assemblage composition compared to sub-regions with low or moderate wetland densities. Species richness increased with wetland age and assemblage similarity increased with plant cover. Species richness in existing mature ponds (more than 50 years old) was approximately 10% higher than created wetlands. Composition showed overall similarity, diversity was similar, but the rate of species accumulation differed between new and mature water bodies. The 300 ha area of wetlands was created from 1996 to 2004 in natural depressions of former pasture, crop or fallow land by soil excavations and damming existing waterways or drainage systems. Wetlands were largely permanent, flow-through water bodies (<2 ha). Fifteen percent of wetlands in sub-regions with low, moderate, and high densities of created wetlands (i.e. 13, 8, and 15) were sampled. A D-shaped hand-net was swept twice at 15 points along each wetland margin in May 2004. Twenty-five mature ponds in the region had been sampled in April of 1996-2003.