Geography

This paper integrates recent efforts to map the distribution of biomes for the late Quaternary with the detailed evidence that plant species have responded individualistically to climate change at millennial timescales. Using a fossil-pollen data set of over 700 sites, we review late-Quaternary vegetation history in northern and eastern North America across levels of ecological organization from individual taxa to biomes, and apply the insights gained from this review to critically examine the biome maps generated from the pollen data. Higher-order features of the vegetation (e.g., plant associations, physiognomy) emerge from individualistic responses of plant taxa to climate change, and different representations of vegetation history reveal different aspects of vegetation dynamics. Vegetation distribution and composition were relatively stable during full-glacial times (21 000-17 000 yr BP) [calendar years] and during the mid-to late Holocene (7000-500 yr BP), but changed rapidly during the late-glacial period and early Holocene (16 000-8 000 yr BP) and after 500 yr BP. Shifts in plant taxon distributions were characterized by individualistic changes in population abundances and ranges and included large east-west shifts in distribution in addition to the northward redistribution of most taxa. Modern associations such as Fagus-Tsuga and Picea-Alnus-Betula date to the early Holocene, whereas other associations common to the late-glacial period (e.g., Picea-Cyperaceae-Fraxinus-Ostrya/ Carpinus) no longer exist. Biomes are dynamic entities that have changed in distribution, composition, and structure over time. The late-Pleistocene suite of biomes is distinct from those that grew during the Holocene. The pollen-based biome reconstructions are able to capture the major features of late-Quaternary vegetation but downplay the magnitude and variety of vegetational responses to climate change by (1) limiting apparent land-cover change to ecotones, (2) masking internal variations in biome composition, and (3) obscuring the range shifts and changes in abundance among individual taxa. The compositional and structural differences between full-glacial and recent biomes of the same type are similar to or greater than the spatial heterogeneity in the composition and structure of present-day biomes. This spatial and temporal heterogeneity allows biome maps to accommodate individualistic behavior among species but masks climatically important variations in taxonomic composition as well as structural differences between modern biomes and their ancient counterparts.

Knowledge of the vegetation and environment of eastern North America during the Last Glacial Maximum (LGM) is important to understanding postglacial vegetational and biogeographic dynamics, assessing climate sensitivity, and constraining and evaluating earth-system models. Our understanding of LGM conditions in the region has been hampered by low site density, problems of data quality (particularly dating), and the possibility that LGM vegetation and climate lacked modern analogs. In order to generate improved reconstructions of LGM vegetation and environment, we assembled pollen and plant macrofossil data from 21 and 17 well-dated LGM sites, respectively. All sites have assemblages within the LGM timespan of 21,000$1500 calendar yr BP. Based on these data, we prepared maps of isopolls, macrofossil presence/absence, pollen-analogs, biomes, inferred mean January and July temperatures and mean annual precipitation for the LGM. Tundra and open Picea-dominated forest grew along the Laurentide ice sheet, with tundra predominantly in the west. In the east, Pinus-dominated vegetation (mainly P. banksiana with local P. resinosa and P. strobus) occurred extensively to 343N and possibly as far south as 303N. Picea glauca and a now-extinct species, P. critchxeldii, occurred locally. Picea-dominated forest grew in the continental interior, with temperate hardwoods (Quercus, Carya, Juglans, Liriodendron, Fagus, Ulmus) growing locally near the Lower Mississippi Valley at least as far north as 353N. Picea critchxeldii was the dominant species in this region. The Florida peninsula was occupied by open vegetation with warm-temperate species of Pinus. Eastern Texas was occupied by open vegetation with at least local Quercus and Picea. Extensive areas of peninsular Florida and the continental interior had vegetation unmatched by any modern pollen samples. The paleovegetational data indicate more extensive cooling in eastern North America at the LGM than simulated by either the NCAR CCM0 or CCM1 climate models. The occurrence of cool-temperate conifers and hardwoods as far north as 34-353N, however, indicates less severe cooling than some previous reconstructions. Paleoclimate inferences for the LGM are complicated by lowered atmospheric CO concentrations, which may be responsible for the open nature and dominance of conifers in LGM vegetation.

Plant formations different from any extant today apparently were widespread in North America and Europe during the last deglaciation, produced by the independent biogeographic responses of plant taxa to climate change. Dissimilarity analyses of modern and fossil pollen samples in eastern North America show that the unique plant associations centered around the Great Lakes at 14 000 calendar years before present (yr BP), with high dissimilarities during 17 000-12 000 yr BP. The late-glacial fossil pollen assemblages are characterized by (1) high abundances of boreal conifers such as spruce and larch relative to their Holocene values, (2) high abundances of herbaceous types (sedge, sage, and ragweed), (3) high abundances of broad-leaved deciduous types (ash, hornbeam, poplar, hazel, and willow), and (4) the low abundance or absence of pine, alder, and birch. When the fossil pollen samples are assigned to biomes using the affinity score technique, the late Pleistocene pollen samples are assigned to mixed parkland, a biome that is not extant in North America today. The fastest vegetational changes occurred 13 000-11 000 yr BP, when the late Pleistocene vegetation reorganized into the Holocene biomes, which have persisted to today. Simulations by the Community Climate Model, version 1 (CCM1), suggest that late-glacial climates were also unlike modern climates, featuring a ''hypercontinental'' mixture of colder-than-present winters, warmer-than-present summers, and lower-than-present precipitation. Dissimilarity analyses of the pollen data and CCM1 simulations for 21 000, 16 000, 14 000, 11 000, and 6000 yr BP show that (1) the temporal and spatial distribution of high dissimilarities in the vegetation (relative to present) coincide with dissimilarities in simulated climate, (2) the timing and spatial distribution of changes in the vegetation and simulated climate also agree, and (3) the largest climatic and vegetational changes follow the peak period of dissimilarity from present. Taken together, these three lines of evidence support the hypothesis that the no-analogue plant associations were in equilibrium with orbital-and millennial-scale climate change. Nonclimatic factors such as low atmospheric CO 2 concentrations and the presence of now-extinct megafauna species may have increased the openness of the Pleistocene vegetation, but by themselves cannot explain the observed mixture of boreal, temperate, and herbaceous taxa in the no-analogue pollen assemblages, nor can they explain the prevalence of no-analogue pollen samples during the late glacial period.

Since 2002, consecutive Israeli governing coalitions have been building a separation wall in the West Bank for the declared purposes of security and separation from the Palestinian population. Building on earlier phases of control, which relied on military orders, cantonment, roadblocks, and checkpoints, the wall functions as a regime of government that colonizes Palestinian life by regulating every nexus of body and space and population and territory. Rather than establishing peace, the wall’s regime of government uses separation as a double
construction of peace and conflict that isolates peace on the Israeli side and conflict on the Palestinian side.

For more than five decades, resource scarcity has been the lead story in debates over environmental politics. More importantly, and whenever environmental politics implies conflict, resource scarcity is constructed as the culprit. Abundance of resources, if at all visited in the literature, holds less importance. Resource abundance is seen, at best, as the other side of scarcity--maybe the successful conclusion of multiple interventions that may turn scarcity into abundance. This paper reinstates abundance as a politico-environmental category in its own right. Rather than relegating abundance to a second-order environmental actor that matters only on occasion, this paper foregrounds it as a crucial element in modern environmental politics. On the substantive level, and using insights from science and technology studies, especially a slightly modified actor-network framework, I describe the emergence and consolidation of a Zionist network of abundance, immigration, and colonization in Palestine between 1918 and 1948. The essential argument here is that water abundance was constructed as fact, and became a political rallying point around which a techno-political network emerged that included a great number of elements. To name just a few, the following were enrolled in the service of such a network: geologists, geophysicists, Zionist settlement experts, Zionist organizations, political and technical categories of all sorts, Palestinians as the negated others, Palestinian revolts in search of political rights, the British Mandate authorities, the hydrological system of Palestine, and the absorptive capacity of Palestine, among others. The point was to successfully articulate these disparate elements into a network that seeks opening Palestine for Jewish immigration, redefining Palestinian geography and history through Judeo-Christian Biblical narratives, and, in the process, de-legitimizing political Palestinian presence in historic Palestine.

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