Habitat determinants of abundance, structure and composition of flying Hymenoptera communities in mountain old-growth forests

Arnan X., Bosch J., Comas L., Gracia M., Retana J. (2011) Habitat determinants of abundance, structure and composition of flying Hymenoptera communities in mountain old-growth forests. Insect Conservation and Diversity. 4: 200-211.
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Doi: 10.1111/j.1752-4598.2010.00123.x

Resum:

1.Old-growth forests have features that endow them with an extraordinary ecological value. These forests are sources of habitat diversity and, consequently, biodiversity, which makes them a basic objective of conservation programs. Insects have been traditionally used as indicators of forest condition. 2.The aim of this study is to uncover patterns of Hymenoptera abundance and diversity, and their relationship with structural features in old-growth forests. We use pan traps to sample the community of flying Hymenoptera in two old-growth forest types (silver fir and mountain pine) with important structural differences. 3.Compared to other surveys of local Hymenoptera communities, our sampling yielded an extremely high number of species (630). 4.At the plot level, the two forest types showed important differences in family richness and diversity, but not in abundance or in species richness and diversity. However, variability in species richness was higher among pine than silver fir plots, leading to overall higher species richness in the former. 5.Species composition also differed between pine than silver fir forests, and these differences were related to important structural differences between the two forest types. 6.Canonical correspondence and multiple regression analysis yielded contrasting habitat requirements among Hymenoptera families and functional groups (bees, sawflies, parasitic wasps and predatory wasps). 7.We conclude that flying Hymenoptera communities can be used as good indicators of forest structure, habitat complexity and conservation status. © 2010 The Authors. Insect Conservation and Diversity © 2010 The Royal Entomological Society.

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Land-cover changes in and around a National Park in a mountain landscape in the Pyrenees

Gracia M., Meghelli N., Comas L., Retana J. (2011) Land-cover changes in and around a National Park in a mountain landscape in the Pyrenees. Regional Environmental Change. 11: 349-358.
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Doi: 10.1007/s10113-010-0138-0

Resum:

The current state of Mediterranean mountain areas has been driven by two main factors: intense traditional human activity and the dynamics of the ecosystem itself. In this study, we examine land-cover changes in a National Park in the Pyrenees mountains (NE Iberian Peninsula), which was designated a protected area 55 years ago. First, we have analyzed spatio-temporal changes in land-cover pattern and forest dynamics from 1957 to 2005. During this period, land-cover dynamics consisted of two main processes: (i) expansion of the forest area and (ii) increasing cover of forests already present in 1957. To analyze the role of the conservation level of the park, we have also compared the results obtained within the park with those of unprotected, peripheral areas. In the two areas with different protection level, dense forests increased throughout the period because of the reduction in forestry activities. The peripheral area showed a higher rate of forest-cover change from 1957 to 2005 compared to the National Park. This higher increase in forest cover in the peripheral area could be related to a higher proportion in the National Park of screes and rocky areas and to the decline and transformation of forest activities in these peripheral, lower elevation areas. © 2010 Springer-Verlag.

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