Arthropod functional feeding groups as indicators of small-scale disturbance: a first approach in Mt. Manunggal, Cebu Island, Philippines

摘要

The growing pressure placed by human disturbances on natural resources creates a need for quick and precise answers about the state ofconservation of different ecosystems worldwide. Hence, identifying and making use of ecological indicators becomes an essential task inthe conservation of tropical ecosystems. This study assessed the effects of small-scale disturbances on terrestrial arthropods and selectfunctional feeding groups (FFGs) that could be used as ecological indicators in one of the protected areas of Central Cebu ProtectedLandscape. Arthropods were sampled within Mt. Manunggal, Cebu Island, Philippines, both in highly-disturbed (S1) and less-disturbedsites (S2) of CCPL from October 2017 to March 2018. Arthropods were collected using a combined transect-quadrat method, where 24quadrats were established within six transects (20 × 20 m) in S1 and S2. All data were analyzed using Odum and Barrett’s formulae forabundance and richness, Shannon Wiener index for diversity and Pielou’s index for evenness. A total of 12 403 arthropods under tendistinct FFGs were recorded, whose abundance contrasted across S1 and S2, with scavenger feeders showing the highest abundance (S1:n = 2363; 19.05%) while seed feeders with the lowest abundance (S1: n = 9; 0.13%; S2: n = 38; 0.67%). In S1, there were n = 6759 under48 arthropod families while n = 5644 under 45 arthropod families were recorded in S2. The diversity index of arthropod assemblages inboth sites (S1: H’ = 1.94; S2: H’ = 1.93) was classified in the medium category, indicated by H’ 3.87. The evenness value in range 0.40 e 0.60 also indicated a medium number of arthropods in both sites. The abundance of arthropods was higher in the highly-disturbedsite, and this pattern seems to be an adequate indicator of anthropogenic disturbance. This novel approach in categorizing arthropodsbased on FFGs provides an important complement to link contrasting patterns of composition to differences in forest functioning andhabitat disturbances across geographical and environmental gradients. This study underlines that habitat disturbances are the maindriver of the variation in arthropod diversity. Potential applications for FFGs as indicators include the choice and evaluation of sitesfor the establishment of protected areas, elaboration of management plans, and the assessment of ecological impacts due to humandisturbances, either for the purpose of licensing or legal compensation.