Projections that the frequency and intensity of extremes in the Asian monsoon will rise are being made with increasing confidence. There is concern that these events may drive south-east Asian dry tropical forest (SASDTF) - an extensive ecoregion affected by this climate system - across critical thresholds. This could have implications both in terms of biodiversity loss from an area of global ecological significance, and for the flow of services that it provides to a populous part of the world. Little work has been done on the threshold dynamics of SASDTF, however, research from dry tropical forests elsewhere indicates that associated ecosystems may be susceptible to abrupt reorganisation to savanna under reduced precipitation regimes, increased rainfall seasonality, or if burnt. This project uses a high-resolution, multi-proxy analysis of two sediment cores extracted from Cambodian crater lakes - situated at the heart of SASDTF - to assess long-term ecological response to these identified drivers. Reconstruction of past climate using geochemical proxies of lake water levels indicates a stepwise weakening of the summer monsoon from 4700 to 450 cal. yrs BP. This trend is punctuated by a notable dry period from 1900 to 1500 cal. yrs BP. Charcoal records demonstrate that fire has been a persistent feature of SASDTF over the past 4700 years. A reconstruction of the ecological history of SASDTF indicates resilience to climatic forcing and periods of high fire activity. As vegetation appears to shift from closed to open forest formations during a weaker summer monsoon or in response to fire activity, the mosaics of open- and closed- units that characterise the ecoregion have been identified as important for future forest persistence. Broadly, this research emphasises the limitations of generalist biome-scale resilience modelling, stressing the importance of long-term, intra-biome level research for predicting ecological response to climatic and anthropogenic forcing
