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Buchori D, Rizali A, Rahayu GA, Mansur I. 2018. Insect diversity in post-mining areas: Investigating their potential role as bioindicator of reclamation success. Biodiversitas 19: 1696-1702. Reclamation can be a pivotal process to return an ecosystem to its condition prior to human disturbance, by recreating a landscape so that its structure and function closely resemble a natural community. Unfortunately, there is a lack of empirical data as to whether reclamation efforts successfully establish sustainable of the ecosystem or not. The objective of this research was to study insect diversity in post-mining areas and investigate their potential role as bioindicators of reclamation success. An ecological research was conducted in post-mining reclamation areas managed by PT. Berau Coal in Binungan, East Kalimantan. We selected sub-areas that had been subject to reclamation efforts for varying periods, ranging from 2 to 10 years, for observation. We also used an area of undisturbed natural forest as a comparison. Inside each of these subareas of different reclamation age, insects were sampled using pitfall traps and malaise traps along a 100-meter transect. Our results showed that insect diversity differed in areas of different reclamation age. Based on CCA revealed that environmental factors i.e. pioneer tree age, vegetation diversity and soil chemistry (N total) affected the diversity of insects in the reclamation area. In particular, NMDS analysis showed different species composition in ant communities found in subareas of varying reclamation age. We conclude that ants are the most useful potential bioindicator to assess reclamation success in post-mining areas.

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Quantitative field measurements of biological nitrogen fixation (BNF) and biomass production by four different understorey pastures in a Pinus radiata-pasture agroforestry system were determined over a period of one year. The trees were two years old at the beginning of this study and the understorey pastures were being cut and removed for silage. The BNF was determined using the ~SN dilution technique. Pastures of ryegrass+clover, cocksfoot+clover, phalaris+clover and lucerne were used. Substantial amounts of BNF were found (71 to 230 kg N ha -l year -~) with lucerne showing the highest N fixation. However, lucerne derived only 71 to 72% of its N from the atmosphere (%Ndfa) during the spring/summer period compared to 83-97% with clovers, thus the net N demand from the soil was substantially higher with lucerne. This caused increased N stress to the trees. Clover in ryegrass+clover pasture fixed more N than the other grass+clover pastures. Although pasture position in relation to trees did not affect annual pasture total DMY and %Ndfa, pastures north of tree row grew better than those in other positions. Trees significantly affected the BNF of legumes and the botanical composition of pastures with highest BNF and legume production occurring in pastures midway between two rows of trees. These results suggest that it would be advantageous to evaluate different legumes and grasses for tolerance of shade and moisture stress in future studies. As the trees studied were only 1.5 to 3 m in height, their effects on BNF, seasonal pasture biomass production and botanical composition are expected to increase with tree dominance in the ecosystem with time. Amounts of N fixed were related to the productivity (i.e. dry matter and N yield) and seasonal persistence of the legumes. The productivity was high in spring and summer and low in autumn and winter.