Human altered ecosystems suitable habitats as well as ecological traps for dragonflies (Odonata).pdfVIP

ORIGINAL PAPER Human altered ecosystems: suitable habitats as well as ecological traps for dragonflies (Odonata): the matter of scale Filip Harabis? ? Ales? Dolny? Received: 27 November 2010 / Accepted: 23 March 2011 / Published online: 3 April 2011  Springer Science+Business Media B.V. 2011 Abstract Habitat loss and degradation can be considered as major threats to freshwater invertebrates. These often irreversible processes lead to reduction of habitat patch quality and cause local extinctions of dragonflies, notably of habitat specialists. However, the biodiversity of specific secondary habitats is very high. Here, we present findings from a 10-year study that intensively monitored odonate fauna in the Upper Silesian industrial coal region having many secondary habitats characterized by very frequent disturbances due to soil instability. We evaluated qualita- tive changes in the dragonfly assemblages on 10 patches using a modified dragonfly biotic index. Data analysis was supplemented by a model examining population dynamics of the threatened dragonfly Leucorrhinia pectoralis, using the capture-mark-recapture method, as an effective indi- cator of habitat quality. We show that dynamics of envi- ronmental conditions in secondary habitats are reflected in population dynamics of dragonfly populations and assem- blages. As frequency of L. pectoralis population extinc- tions within the patch is considerable and independent of size and spatial isolation of single habitats, these can be regarded as ecological traps. Nevertheless, the metapopu- lation dynamics may be a key adaptation of dragonflies to frequent freshwater habitat disturbances. We suggest that local extinctions are effectively balanced with (re-)colonization of newly emerging freshwater habitats. These findings have implications for potential conservation management of specific human-made habitats, because secondary habitats with a great diversity of succession stages arising directly as a consequence of