Southeast (SE) Asia has been undergoing extensive changes in rural and urban areas as well as in the rural-urban transition zone. Rapid population growth and climate change effects have exerted excessive stresses resulting in intensive 3D urbanization and expansive land cover and land use change, for which policymakers must have relevant synthesis information.In SE Asia, countries from the Mainland (Vietnam, Thailand, Laos,andCambodia)toPeninsular(Malaysia)andOceania(Indonesia),consideredhere as the MPO, are among the most illustrative examples where a complex confluence of population, land/water, and climate system change is takingplace.The MPO with stark land use conversions and extreme urbanization represents important aspects of land consumption that is not captured by metrics associated with sustainable development

The overarching science question in this research is how land cover (LC), land use (LU), and demography (DG) evolve and interact in this highly dynamic and vulnerable setting. We hypothesize that physical-human feedback processes are exacerbated by urbanization, agriculture conversion, and climate factors forcing LC, LU, and DG processes to become non-stationary, thereby causing unprecedented impacts that are not predictable from past observable trends in transformative regions and in anomalous hot-spot areas where multi- scenario flexibility must be considered in policy development. In contrast, for transitional regions undergoing weak or gradual changes, we hypothesize that trajectories can be associated with continual environmental trends and sociodemographic drivers so that past reference of the LC, LU, and DG changes can be used to plan for future policy. Thus, the goals of this synthesis study are:

• Goal 1 (G1): To capture physical-dimension features of the land cover (LC) and land use (LU) in the MPO using primarily satellite data products, together with ancillary surface networks and field observations. These will identify and quantify spatiotemporal variations along the rural-urban continuum that spans across the multi-sector landscape undergoing transitional, transformative, or anomalous hot-spot changes in time (1D) and in space (3D).
• Goal 2 (G2): To capture human-dimension features of the socioeconomic fabrics in the MPO. These consider spatiotemporal variations associated with LU change involving land consumption and conversion, biophysical alterations such as deforestation/restoration, environmental impacts such as air/water pollution, climate change such as sea level rise, and geophysical change such land subsidence. These are crucial to address both land use at risk and population at risk under deteriorated ecoservice values.
• Goal 3 (G3): To combine the both physical-human dimensions (G1+G2) within a synthesis framework of integrations, interactions, and linkages (Figure 1). These connect the LCLUC to the forms, forcing/feedback processes, and consequences of environmental and socioeconomic changes in the MPO to test the stationarity versus non-stationarity hypotheses, using time-series methods, in regions where transitional, transformative, or hot-spot changes are identified. The outcomes from the synthesis are intended to lend scientific support to the strategic development of proactive policies that are regionally relevant and effective.

Given G1-G3, we will utilize methods, products, results, and accumulated knowledge achieved from previous and current studies, with 3D products overcoming 2D shortfalls. The research team involves an extensive consortium of 7 investigators, and 52 non-cost collaborators from 15 countries. This research will be coordinated with the international science and practice community in yearly workshops. As closely relevant to the LCLUC SARI Synthesis proposal call, this effort will contribute to advancing sustainable development, policy planning, proactive strategy, and climate adaptation for the MPO in SE Asia.