The width of riparian habitats for understory birds in an Amazonian forest

Abstract

Riparian habitats are important for the maintenance of regional biodiversity. Many studies have compared bird distributions between riparian and non-riparian habitats but have not established how wide riparian habitats used by birds are, as measured by distance from the nearest stream. We investigated the distribution of understory birds along gradients of distance from streams, soil clay content, and slope in a central Amazonian forest, by mist-netting birds three times in 45 plots. We used nonmetric multidimensional scaling (NMDS) to reduce the dimensionality of species quantitative (abundance) and qualitative (presence-absence) composition to one multivariate axis. Estimates of the width of riparian habitats as indicated by understory birds depended on the community attribute considered, measuring 90 m for species quantitative composition and 140 m for species qualitative composition. Species distributions were correlated with clay content but were independent of slope, while distance from streams was positively correlated with clay content but independent of slope. Clay content affects plant species composition, which in turn, may influence bird species composition. However, distribution patterns of birds in relation to distance from streams are consistent among studies carried out in many different temperate and tropical regions, indicating an effect of distance from streams itself. Protection of riparian habitats is one of the most widely used conservation strategies, and Brazilian environmental legislation mandates the protection of a 30 m wide strip of riparian vegetation on either side of small streams. We show that the protected strip should be much wider and recommend strategies to place other forms of land protection contiguous with riparian areas so that Brazilian environmental legislation better fulfills its role of protecting biodiversity associated with riparian habitats.

Spatial Variation in Bird Community Composition in Relation to Topographic Gradient and Forest Heterogeneity in a Central Amazonian Rainforest

“…Therefore, we recommend that long-term monitoring of bird communities using standardized methods be done at the RFAD [54] in order to ensure that processes of species loss (if unavoidable) are well documented. The only active measure that can potentially delay or protect the RFAD from species loss is maintaining the connectivity of the RFAD on its eastern edge and creating a protected forest corridor from the RFAD to other large tracks of forest north of Manaus.…”

Synthesis of the first 10 years of long-term ecological research in Amazonian Forest ecosystem – implications for conservation and management

“…Diverse studies in LTER-Site #1 have shown that species composition of distinct assemblages such as plants, frogs and tadpoles, snakes and birds, varies in relation to distance from water bodies (Drucker et al, 2008;Rodrigues et al, 2010;Fraga et al, 2011;Bueno et al, 2012;Schietti et al, 2013). In RFD, Drucker et al (2008) showed that the floristic composition of understory herbs is distinct from that found up to approximately 100 m horizontally from the edge of streams, or above about 70 m above drainages, varying slightly with the size of the stream valley.…”

Uncertainty and the design of in-situ biodiversity-monitoring programs

“…Pezzini et al 2012) and ATDN (Stropp et al 2009, ter Steege 2013) vegetation networks. The same plots have been surveyed for taxa as diverse as mites , ants , frogs (Menin et al 2007) and birds (Bueno et al 2012). There is a logical trade-off.…”

“…Menin et al 2007, Bueno et al 2012), but some studies have investigated relationships among different groups of organisms (e.g. Baccaro et al 2012) and studies are starting to investigate how relationships change over time (e.g.…”