Patricia L. Fall

Timberline fluctuations and late Quaternary paleoclimates in the Southern Rocky Mountains, Colorado

Pollen and plant macrofossils from eight sedimentary basins on the west slope of the Colorado Rocky Mountains document fluctuations in upper and lower timberline since the latest Pleistocene. By tracking climatically sensitive forest boundaries, the moisture-controlled lower timberline and the temperature-controlled upper timberline, paleoclimatic estimates can be derived from modern temperature and precipitation lapse rates. Pollen data suggest that prior to 11 000 yr B.P., a subalpine forest dominated by Picea (spruce) and Pinus (pine) grew 300–700 m below its modern limit. The inferred climate was 2–5 °C cooler and had 7–16 cm greater precipitation than today. Abies (fir) increased in abundance in the subalpine forest around 11 000 yr B.P., probably in response to cooler conditions with increased winter snow. Pollen and plant macrofossil data demonstrate that from 9000 to 4000 yr B.P. the subalpine forest occupied a greater elevational range than it does today. Upper timberline was 270 m above its modern limit, suggesting that mean annual and mean July temperatures were 1–2 °C warmer than today. Intensification of the summer monsoon, coupled with increased summer radiation between 9000 and 6000 yr B.P., raised mean annual precipitation by 8–11 cm and allowed the lower limit of the subalpine and montane forests to descend to lower elevations. The lower forest border began to retreat upslope between 6000 and 4000 yr B.P. in response to drier conditions, and the upper timberline descended after 4000 yr B.P., when temperatures cooled to about 1 °C warmer than today. The modern climatic regime was established about 2000 yr B.P., when the summer precipitation maxima of the early and middle Holocene were balanced by increased winter precipitation.

Pollen Accumulation in a Montane Region of Colorado Usa a Comparison of Moss Polsters Atmospheric Traps and Natural Basins

Pollen spectra from three types of modern collectors — Tauber traps, moss polsters, and surface muds from small basins — are compared to illustrate pollen dispersal and sedimentation in an alpine setting. Pollen frequency data demonstrate that the atmospheric collectors and moss polsters provide the most distinct vegetation signals. In forest stands, pollen frequencies for each of the five main forest trees — Picea engelmannii, Abies lasiocarpa, Pseudotsuga menzeisii, Pinus contorta, and Populus tremuloides — are highest where the trees grow. Thus, each forest type can be recognized by its dominant arboreal taxa. The distinctions between vegetation types are less pronounced in pollen spectra from surface muds collected from small lakes. Surface lake samples collected above treeline have high frequencies of conifer pollen, particularly Pinus pollen. Picea and Abies pollen frequencies (averaging 16% and 2%, respectively) are somewhat lower above treeline than in the sub-alpine forest (where they average 20% and 7%). This suggests that the upper forest border can be recognized by its pollen spectrum. However, Pinus pollen above treeline is comparable to samples collected in the Pinus contorta forest (approximately 40%). The pollen accumulation rates in small bogs in forested settings and above treeline are comparable to the atmospheric pollen influx in these environments. The pollen influx in lakes surrounded by closed forests is only 10–20% greater than the accumulation rates in atmospheric collectors. Thus, for bogs in forests and krummholz, and for lakes without inflowing streams in forest stands, fluvial introduction of pollen is minimal. Atmospheric collectors and moss polsters may provide accurate modern analogues for fossil sites in these environments. However, atmospheric pollen accumulation accounts for only one-fifth of the pollen influx in an alpine lake without an inflowing stream, suggesting that in alpine tundra pollen is concentrated by slope wash across open steep terrain before it is deposited in small ponds. Because of this increased concentration, and because much of the pollen in alpine settings comes from plants growing at much lower elevations, alpine pollen spectra become badly distorted. Therefore, palynological inference of alpine tundra from fossil pollen spectra may be difficult. Discriminant analyses are used to test the degree of similarity between vegetation types according to their pollen spectra. While pollen spectra from moss polsters differ significantly by vegetation type, this is not true of pollen spectra from surface lacustrine samples. Bogs offer depositional settings comparable to moss polsters and atmospheric traps. All three of these can provide useful modern analogues for fossil pollen from bogs. In contrast, pollen spectra from small lakes, which tend to be less distinctive, particularly in open vegetation, may be difficult to interpret. Future calibration of modern pollen and vegetation with fossil pollen spectra should focus on bogs and small closed basin lakes without inflowing streams.

The European Modern Pollen Database (EMPD) project

Modern pollen samples provide an invaluable research tool for helping to interpret the quaternary fossil pollen record, allowing investigation of the relationship between pollen as the proxy and the environmental parameters such as vegetation, land-use, and climate that the pollen proxy represents. The European Modern Pollen Database (EMPD) is a new initiative within the European Pollen Database (EPD) to establish a publicly accessible repository of modern (surface sample) pollen data. This new database will complement the EPD, which at present holds only fossil sedimentary pollen data. The EMPD is freely available online to the scientific community and currently has information on almost 5,000 pollen samples from throughout the Euro-Siberian and Mediterranean regions, contributed by over 40 individuals and research groups. Here we describe how the EMPD was constructed, the various tables and their fields, problems and errors, quality controls, and continuing efforts to improve the available data.

Seeds of Civilization: Bronze Age Rural Economy and Ecology in the Southern Levant

This paper considers the economic and environmental impacts of emerging regional commerce that accompanied the rise and collapse of early Near Eastern urbanism. We integrate regional data on settlement and vegetation with detailed evidence of rural agriculture from two Bronze Age villages in the Jordan Valley. This approach is explicitly rural, in light of the largely rural character of Levantine civilization, and in response to more orthodox analytical perspectives focused on the first cities. Long-standing interest in the advent of agriculture now reveals that intensive localized depletion of woodland resources followed the aggregation of sedentary agrarian communities in the eighth through sixth millennia B.C., while the development of specialized pastoralism established one potential source of more extensive, subsequent defoliation. We argue, however, that regional human impacts on Levantine vegetation were triggered only with the genesis of Bronze Age cities and urbanized economies in the third and s...

Agricultural Intensification and the Secondary Products Revolution Along the Jordan Rift

The ecological impacts of early agriculture in the Near East remained localized prior to the intensified production of derivative plant and animal products, beginning in the fourth millennium B.C. One aspect of this “secondary products revolution” (Sherratt, 1980a, 1983) involved the adoption of animal traction and increased production of rendered animal commodities (e.g., wool and dairy). However, most of the pervasive regional effects of this revolution followed from the domestication and increasingly intensive cultivation of orchard crops that generated marketable secondary products (e.g., olive oil, wine, and dried fruits) and encouraged widespread deforestation. In the southern Levant this revolution encouraged, and was encouraged by, the rise and fall of Bronze Age towns and their mercantile influences. Botanical and palynological data from the Jordan Rift reveal a complex discontinuous legacy of changes wrought by the secondary products revolution that have molded the agrarian ecology and anthropogenic landscapes characteristic of the region today.

The intertropical convergence zone modulates intense hurricane strikes on the western North Atlantic margin

Most Atlantic hurricanes form in the Main Development Region between 9°N to 20°N along the northern edge of the Intertropical Convergence Zone (ITCZ). Previous research has suggested that meridional shifts in the ITCZ position on geologic timescales can modulate hurricane activity, but continuous and long-term storm records are needed from multiple sites to assess this hypothesis. Here we present a 3000 year record of intense hurricane strikes in the northern Bahamas (Abaco Island) based on overwash deposits in a coastal sinkhole, which indicates that the ITCZ has likely helped modulate intense hurricane strikes on the western North Atlantic margin on millennial to centennial-scales. The new reconstruction closely matches a previous reconstruction from Puerto Rico, and documents a period of elevated intense hurricane activity on the western North Atlantic margin from 2500 to 1000 years ago when paleo precipitation proxies suggest that the ITCZ occupied a more northern position. Considering that anthropogenic warming is predicted to be focused in the northern hemisphere in the coming century, these results provide a prehistoric analog that an attendant northern ITCZ shift in the future may again return the western North Atlantic margin to an active hurricane interval.

Household and community behavior at Bronze Age Politiko-Troullia, Cyprus

Abstract We investigate intrasite patterns of artifacts and floral and faunal data to interpret household and community behavior at the Middle Cypriot (Bronze Age) village of Politiko-Troullia in the foothills of the Troodos Mountains, Cyprus. Floral evidence indicates cultivation of orchard crops (e.g., olive and grape), as well as the persistence of woodlands that provided wood for fuel. Animal management combined herding of domesticated sheep, goat, pig, and cattle with the hunting of Mesopotamian fallow deer. Metallurgical evidence points to the production of utilitarian copper tools in household workshops. Group activities are reflected by the deposition of anthropomorphic figurines, spinning and weaving equipment, and deer bones in an open courtyard setting. In sum, Politiko-Troullia exemplifies a diversified agrarian economy on a distinctly anthropogenic landscape that fostered the development of household and supra-household social differentiation in pre-urban Bronze Age Cyprus.

Plant Dispersal, Introduced Species, and Vegetation Change in the South Pacific Kingdom of Tonga

Abstract: Dispersal guilds hold key ecological implications for the vegetation history of islands. This study considers dispersal vectors in conjunction with species origin and growth form to characterize vegetation dynamics on the islands of Tonga in the South Pacific. Data for over 700 species compiled from published literature on the plants of Tonga support a comparative study of dispersal mechanisms and growth forms for native flora, species brought by Polynesian settlers, and taxa introduced since European contact. The indigenous flora, predominantly trees, is characterized primarily by endozoochorous (internal) dispersal through birds and bats. European introductions, primarily herbs, disperse commonly through epizoochorous (external) animal dispersal. Bat dispersal is most important for overstory indigenous and Polynesian trees and vines. In addition, rodents commonly eat seeds of native rain forest trees. The understory, which is overwhelmingly introduced, consists of wind-dispersed and externally animal-dispersed species, which are often early successional. Rain forest thinning encourages establishment of wind-dispersed species and nonnatives. Thus, the prospect of sustained native flora in Tonga would be enhanced by the preservation of bats, a particularly important dispersal vector for indigenous and endemic species, and by the eradication of introduced rats.

Species Origins, Dispersal, and Island Vegetation Dynamics in the South Pacific

We characterize the vegetation of the Kingdom of Tonga, South Pacific, by exploring the effects of species–area relationships, species isolation, and long-distance dispersal. Published literature provides data for eleven main islands of Tonga on species richness, vegetation types, origins, and dispersal mechanisms. Island area, maximum elevation, distance from neighboring archipelagos, and island geology provide key variables with which to consider the configuration of Tongas floral biodiversity. Vegetation communities are evaluated by dispersal mechanisms, species origins, and island age as reflected by geology. Species–area relationships are significant for all plant species and for ancient and modern introductions, and species richness shows significant relationships to maximum elevation for indigenous plants and modern introductions. In contrast, species richness on the islands of Tonga does not correspond to patterns expected for species–isolation relationships with the nearest archipelagos of Samoa and Fiji. Plant dispersal spectra vary significantly according to island topography, geology, vegetation types, and plant species origins. The youngest volcanic islands have the most wind-dispersed species, whereas the older limestone islands have more bird, water, and human-dispersed plants. Tongatapu, the largest and longest inhabited island, reflects the legacy of a deeply humanized landscape where more than half the plants are introduced. In contrast, on the sparsely populated, more remote islands, and in many vegetation types, 70 to 90 percent of the plants are native. Evidence for species introductions, varying impacts on different vegetation types, and associated changes in dispersal spectra reveal key aspects of biogeographic dynamics in Tonga and potentially for island biogeography elsewhere.

A Stone Plank Figure from Politiko- Troullia , Cyprus: Potential Implications for Inferring Bronze Age Communal Behavior

Plank figures are hallmark anthropomorphic depictions that illuminate Bronze Age society on Cyprus. The excavation of a rare limestone plank figure from a public space at Politiko-Troullia is interpreted in conjunction with spatial patterning of ceramic plank figures, plant macrofossils, animal bones, ground stone, spindle whorls, and metallurgical evidence to infer communal behavior at this Early/Middle Cypriot—period settlement. The Politiko-Troullia stone plank figure is significant as the sole example from a fully documented excavated context and as part of a growing body of evidence for the creation of social identities in emerging complex society on Cyprus.