Karina Kwapil

Karina Kwapil

karina_kwapil@yahoo.com


Herbivore communities on Alnus acuminata in relation to different reforestation methods – a case study in the cloud forest zone of Ecuador

Deforestation continues to be an issue of concern in many tropical nations. Active reforestation has been proposed as an ecologically and economically sustainable option to reclaim degraded habitats. Reforestation may help reduce the negative impacts of land degradation and loss of biodiversity. In a cloud forest zone of southern Ecuador, plantations of native tree species including Alnus acuminata were established along a natural succession gradient of abandoned pastures. The aim of the present study was to investigate whether reforestation within successional gradients reveal systematic differences with regard to their associated communities of herbivorous insects and the extent of herbivory, in comparison with herbivore assemblages on A. acuminata in natural forest. In total, 1711 arthropod individuals were collected. 92 % of the insects were herbivorous. Chewing phytophages predominated (969 individuals, 55 species), with Chrysomelidae and Curculionidae constituting the majority of specimens. Sucking phytophages were less abundant (453 individuals, 36 species). The most disturbed habitat (´pasture`) exhibited highest abundance of chewing phytophages in concordance to highest observed value of leaf consumption (22%) and lower abundance of potential natural enemies. In the opposite pattern, sucking phytophages and predators (mainly spiders) showed highest abundance values in the natural forest, with lower leaf damage. Early successional (´shrub´) and mid- successional habitats (´fern´) were intermediate in abundance examination, also in terms of herbivory impact. Regard to species richness, herbivores species showed only marginally increased along the successional gradient with by far highest values found in natural forest. However, species composition of herbivore communities of early- successional habitats (i.e. shrub) showed slight overlap with the forest community. Thus, resulted differences within herbivore insects among habitats, are partially explained by prevalent vegetational structure and -diversity, abundance of natural enemies and microclimate conditions. This study suggest that the use of Alnus acuminata for reforestation, at status quo, support local herbivore biodiversity, yet at a moderate extent.