A fisherman collecting marsh clams in a river in Aceh’s peat swamps (Robert Nickelsberg)
Te incidence of major landslides likewise shows signs of in- creasing over recent years (Serambi 2010a). In Aceh, the most acute problems are in the central Alas valley. Since the 1980s there have been numerous serious flash floods and landslides, many of them involving human fatalities, and most of which have been directly linked to large-scale illegal logging in adja- cent lowland stretches of Sumatran orangutan habitat. As early as 1982, 13 people were killed by landslides in the Alas valley as a direct result of forest clearing for cultivation on a steep slope (Robertson and Soetrisno 1982).
Te peat swamps also serve as a buffer against floods. Tey absorb water and dampen peaks and troughs in rainfall, fa- cilitating a more consistent discharge into streams and rivers. Local communities in Tripa already notice this as a result of conversion of the forests to oil palm plantations. Tey have consistently reported a marked increase in both the frequency and extent of floods since 2000, when PT. Gelora Sawit Mak- mur completed clearance of its concession (8,604 hectares) (PanEco 2008). In 2010, peat areas in Tripa where thousands of people live were flooded, with flood depths between 1 and 1.5 m, isolating the communities living in and around Tripa (Serambi 2010b).
Fisheries Fishing is a very important source of livelihoods, both for cash income and for local consumption. Fishing occurs mainly in rivers and in the peat swamps, but some ocean fishing is also influenced by rivers flowing out of the forest systems (van Beu- kering et al. 2003). One of the most sought after river fish in the region is ikan jurung (Tor spp.). Although still fairly com- mon in the major rivers, fishermen report that both the num- ber and size of the fish they catch are declining (Wind 1996). In the Tripa peat swamps, fishermen report that fish harvests
have generally declined by almost half, to just 60% of former levels, due to the massive land conversion that has taken place there since the Aceh peace agreement in 2005 (Tata and van Noordwijk 2010).
Prevention and limitation of fires Lowland forests typically have high humidity and stable tem- peratures, such that fire risks are normally negligible. When forests are logged, the canopy is opened up, resulting in lower
Using fires to clear land in Aceh (Perry van Duĳnhoven)