, 2001 and Moran, 2010). The USLE’s land-cover factor (i.e. C-factor), whose unit-less values range from 0 to 1 depending on cover type, exerts the single strongest control on soil-erosion model variance ( Toy et al., 1999). Impervious surfaces and water bodies are easy to discount as sediment contributors in erosion models as soils remain unexposed, resulting in a cover-factor value of zero; the effects of bare soil

exposure on sediment yields lie on the other end of the spectrum and corresponding land covers are, given their high erosivity, affixed with a cover-factor of 1 ( Wischmeier and Smith, 1965 and Wischmeier and Smith, 1978). Vemurafenib nmr Erosion factors have also been developed for forested land covers; however, their published C-factors vary by three orders of magnitude ( Table 1). This is largely due to the influence of sub-factors relating to canopy cover and soil reconsolidation in producing varying

effects on soil loss within forested areas ( Dissmeyer and Foster, 1981). Chang et al. (1982) also observe a range from 0.00014 for undisturbed forest to 0.10 for cultivated plots as a function of decreased canopy, litter, and residual stand values. Published C-factors therefore provide metrics that are only at best suitable for application to PD0325901 particular regions or forest types for which vegetation effects on soil loss have been empirically evaluated ( Table 1). Specific controls of urban forest covers on sediment yields are not understood despite a prominence of urban forests in many regions. A study analyzing land cover in 58 US cities with population densities exceeding 386 people per km2 reports of city-wide urban forest covers as high as 55%, making this one of the most prominent urban land-cover types ( Nowak et al., 1996). Determining Methocarbamol unconstrained USLE model-input parameters, such as a C-factor for urban forest cover, requires knowledge of sediment yields as a calibration

tool. Accretion records in large reservoirs can provide insight into basin-scale trends ( Verstraeten et al., 2003 and de Vente et al., 2005), but fail to resolve local changes in erosion due to the tremendous buffering capacities of large watersheds, which increase with drainage-basin size ( Walling, 1983, de Vente et al., 2007 and Allen, 2008). Verstraeten and Poesen (2002) evaluate the possibilities of looking at the small end of the watershed-size spectrum by investigating sediment deposits in small ponds. They highlight the importance of these understudied watersheds in bridging the data gap between plot studies and investigations of sediment loads in large rivers. Sediment yields from small catchments are commonly evaluated using accretion records from reservoirs ( Verstraeten and Poesen, 2001 and Kouhpeima et al., 2010).

C., though some islands such as Trinidad that skirt the northern South American Coast were settled even earlier when sea levels were lower. Archaic groups settled islands primarily in the northern Lesser Antilles and Puerto

Rico, particularly Antigua with its high quality lithic materials (Keegan, 2000). Archaic groups apparently bypassed or quickly moved through nearly all of the southern islands except for Barbados (Fitzpatrick, 2012) for reasons that are not well understood, though it could be related to high levels of volcanism in the region (Callaghan, 2010). Archaic populations, once thought to have been mostly aceramic and nomadic foragers who targeted seasonally available foods (Hofman and Hoogland, 2003 and Hofman et al., 2006), are now known to have produced pottery (Rodríguez Ramos, 2005 and Keegan, 2006), and brought with them a number of plant species from South America, including the Panama tree (Sterculia selleckchem apetala), yellow sapote (Pouteria campechiana), wild avocado (Persea americana), palm nutshells (Acrocomia media), primrose (Oenothera sp.), wild fig (Ficus sp.), and West Indian cherry (Malphigia

sp.) ( Newsom, 1993 and Newsom and ABT-888 mw Pearsall, 2002; see also Keegan, 1994:270; Newsom and Wing, 2004:120). Archaic groups also exploited marine and terrestrial vertebrates and invertebrates, though the number of species harvested was generally few in number; there is no good evidence that these groups translocated animals to the islands. While population densities during the Archaic Age were probably low, there are signs that these groups affected local environments to some degree, including the extinction of giant sloths (Genus Phyllophaga and Senarthra) ( Steadman et al., 2005) and nine taxa of snakes, lizards, bats, birds, and rodents from sites on Antigua dating to between 2350 and 550 B.C., which are either extinct or were never recorded historically ( Steadman et al., 1984). For both cases, the timing of vertebrate extinctions is coincident with human arrival independent of major climatic Fludarabine mouse changes. Given that Antigua also has the densest concentration of Archaic Age sites in

the Lesser Antilles (with over 40 recorded, compared to other islands which may have only a few at most), these impacts to native fauna are much more likely to be anthropogenic ( Davis, 2000). During the early phase of the Ceramic Age (ca. 550 B.C.–550 A.D.), another group known as Saladoid settled the Lesser Antilles and Puerto Rico. While there is ongoing debate about their modes of colonization and direction they may have taken in moving into the islands (Keegan, 2000, Callaghan, 2003, Fitzpatrick, 2006 and Fitzpatrick et al., 2010), it is clear that these groups were related to those in South America based on the translocation of native South American animals and a wide array of stylistic and iconographic representations in rock art, pottery, and other artifacts such as lapidary items.