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Paleoecological data provide insight into patterns of change in vegetation and in the factors, such as climate and disturbance, that cause vegetation change. Disturbance by fire, insect, and mammalian herbivores and, in floodplains, flooding are the primary drivers of changes in population structure, community composition, and species distribution in the boreal forest on time scales of years to decades (Chapter 7). On longer time scales, such as centuries to millennia, the role of variation in regional climate in determining compositional changes in the boreal forest is also clearly visible. Variability in regional climate may act directly on boreal species (e.g., causing changes in species distributions) or indirectly, by altering disturbance regimes. Proxy records of environmental and ecological change (e.g., pollen and macrofossils in lake sediments, tree rings) are selective in the kind of information they record. Evidence of fires, for example, is more persistent and thus better represented in the paleoecological record than is evidence of mammalian herbivory. For this reason, our understanding of long-term patterns of compositional and structural change in the boreal forest is limited to an analysis of the effects of a few key drivers of change, primarily climate and fire. In this chapter, we offer a long-term perspective on changes in climate and disturbance regimes and their relationship to major changes in vegetation. We first consider multimillennial time scales and discuss the role of climate and disturbance in driving the two major vegetation transitions that have occurred during the Holocene (the past 12,000 years). We then explore evidence for spatial and temporal variation in disturbance regimes during the late Holocene. Much of the terrain that is currently occupied by the Alaskan boreal forest remained ice-free during the glacial episodes of the Quaternary period (Pleistocene and Holocene), which spans the past 1.8 million years. Alaska forms part of the largely unglaciated Beringian region (named after the Bering Strait that lies at its heart; see Hopkins 1967) that extends from the Kolyma River in Siberia to the MacKenzie in northwest Canada and constitutes ca. 30% of the circumboreal zone.

Coastal environments of Southeast Asia have been discussed in Chapter 11. This chapter focuses on the utilization of the region’s coastal resources, reflecting not only its varied physical characteristics but also the traditional practices and more modern economic influences that have developed along the coastal regions. Historically, the region serves as an important link between trading routes to Western and Eastern Asia. Many sea battles were fought here between local potentates and foreign powers to win control of the spice trade. A number of the coastal villages developed into important coastal cities, e.g. Cebu, Malacca, Singapore, or in recent years, into coastal tourist resorts, e.g. Pattaya, Kuta. Within the region, there are still strong cultural traditions in the use of coast, although these are being eroded or replaced by more modern or economic practices. For example, the beach forms the traditional recreational area for farmers after the harvest season in Lombok and the east coast of Peninsular Malaysia. Traditionally, the Balinese attach a low economic value to the coast, but this has been replaced in modern times by new and high economic values for tourism, residence, and other uses. The demands for the coastal areas for different uses have various impacts, many of which are detrimental to the coastal environment and may lead to conflicts between users. This chapter relates people with the coastal environment in terms of living and non-living marine resources. Specifically, it discusses several major coastal uses, and their impacts and attempted solutions, to development-related problems. A holistic approach in coastal zone management to solve the problems is advocated, and the implementation and success of this approach assessed. This is also considered within the future and wide-ranging context of climate change and attendant sea-level rise. The definition of a ‘coastal zone’ in Southeast Asia is variable and difficult, as not all states have coastal zone management acts or legislation to define the coastal zone. For the purposes of this chapter, the coastal zone is taken as a variable area defined by not only biogeomorphological characteristics but also the major types of use.

The intricate coastline of Southeast Asia, and its many islands and island groups—Indonesia alone has over 17 500 islands—contains 32 per cent (91 700 km2) of the world’s shallow coral reefs (Spalding, Ravilious, and Green 2001). While sedimentary regimes appear to restrict reef development in the East China Sea, the Gulf of Thailand, the South China Sea, and around the island of Borneo, reefs are well developed elsewhere. Fringing reefs characterize island coastlines, and there are also barrier reefs and, in the deeper waters of the South China Sea and to the east, atoll-like reef structures. Although the region has a distinguished history of reef studies—in which the pioneering work of R. B. Seymour Sewell, J. H. F. Umbgrove, and Ph. H. Kuenen on the Snellius expedition (1929–30) come particularly to mind—the lack of detailed information about many areas remains considerable. The coral reefs, and their associated shallow-water ecosystems, within this region are the product of both historical and contemporary processes. A wide range of hypotheses to explain coral distributions have been proposed. These include the importance of the widespread availability of suitable shallow substrates for coral growth with submergence histories determined by regional tectonic and sea-level dynamics (e.g. Hall and Holloway 1998), the variety of habitats present (e.g. Wallace and Wolstenholme 1998), and the more contemporary roles of high sea-surface temperatures and ocean current circulation patterns, including the dynamics of western Pacific Ocean–eastern Indian Ocean connectivity (Tomascik et al. 1997a). Both sets of controls show wide variation across the region. Thus, for example, geological settings range from tectonically stable platforms to rapidly uplifting plate collision zones of considerable seismic and volcanic activity. Present-day environments vary from equable, tranquil interior seas to cycloneand swell wave-dominated environments on the region’s margins. Added to these controls are the perturbations introduced by, for example, periodic coral bleaching and biological catastrophes (e.g. Crown of Thorns starfish infestations; Lane 1996). Taken as a whole, therefore, the coral reefs of Southeast Asia demonstrate enormous complexity and considerable dynamism. These reef resources are, however, under considerable pressure from large, and growing, populations and economic development.