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Large Tracts (large + tract)
Selected AbstractsFire-mediated interactions between shrubs in a South American temperate savannahOIKOS, Issue 9 2009Fernando Biganzoli We examined spatial patterns of fire-caused mortality and after-fire establishment of two dominant shrub species, Baccharis dracunculifolia and Eupatorium buniifolium in a humid temperate South American savannah. Our objective was to determine whether fires mediate in interactions between these two species. After a natural fire burned a large tract of savannah, we established two plots (respectively 550 and 500 m2) within which we mapped all surviving and dead shrubs as well as all individuals of shrub species that recruited in the following year. We used techniques of point-pattern analysis to test specific null hypotheses about spatial associations in the distribution, mortality, and establishment of shrubs. Results support the notions that fire mediates interactions between these two species. Fire-caused death of E. buniifolium tended to occur selectively in the vicinities of Baccharis individuals, and recruitment of B. dracunculifolia tended to be concentrated in the places of dead shrubs. These responses, however, were contingent on local abundances of shrubs which depend in part from the recent fire history. Anthropogenic perturbation of the natural fire regime would have therefore distorted the role of fire mediated interactions as drivers of the dynamics of the vegetation of this temperate savannah. [source] The hidden record: Late Holocene landscapes and settlement archaeology in the Lower Ohio River ValleyGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 2 2002C. Russell Stafford From extensive backhoe trenching and coring in the Great Miami,Ohio River confluence region, in conjunction with a large suite of radiocarbon ages, we have identified large tracts of late Holocene alluvium. Thick blankets of Historic alluvium (post-settlement) may also cover levees of the Ohio River. In conjunction with other studies in the Outer Bluegrass Region of the lower Ohio River valley, it is possible to document an association between floodplain Mollisols, Inceptisols, and Entisols and late Holocene-aged landforms. Levees appear to have stabilized between 1000 and 2000 yr B.P. Although buried soils are rare, archaeological materials were ubiquitous in late Holocene Landform Sediment Assemblages. Because a substantial volume of valley fill is late Holocene in age, Woodland sites of all types are frequently buried, and Fort Ancient sites may be buried by Historic alluvium. Therefore, if Woodland or later settlement studies in this region are based on surface evidence alone, they are likely to be biased. © 2002 John Wiley & Sons, Inc. [source] Geographic distribution and population size of the mountain tapir (Tapirus pinchaque) in ColombiaJOURNAL OF BIOGEOGRAPHY, Issue 1 2002D. J. Lizcano Aim We conducted a study to estimate the past and present distribution and population size of T. pinchaque in Colombia. Location The study included all mountain ranges above 2000 m. Methods The past distribution was obtained by plotting on a map of past distribution of montane rain forests, the geographical locations with the name `danta' or `tapir' above 2000 m obtained from topographic maps, the locations cited in bibliographic references, and the results of interviews in the 530 Andean municipalities. The present distribution was obtained by plotting the present distribution of montane rain forests, the results of interviews and ground control. Population size was estimated by combining measurements of population density with maps of present distribution. Results In the past, the species occurred in the central and eastern Cordilleras, as well as in the Andean Massive where the three cordilleras merge in the south of the country. Currently, the species occurs in the central Andes south of Nevados National Park, and in the eastern Andes, south of Paramo de Sumapaz, Bogotá. According to our most optimistic estimates, there are about 2500 tapirs in the Andes of Colombia. Main conclusions These individuals occur in a total of thirty-five forest patches that range from 5 to 3700 km2. Only five to six fragments have the minimum necessary size (826 km2) to maintain at least 150 individuals, the estimated number to maintain viable population in the short term. The populations most threatened are those of the central Cordillera between P.N. Las Hermosas and P.N. Nevado del Huila where large tracts of mature montane forests are being converted to opium fields. [source] Population status and behaviours of the Samoan flying fox (Pteropus samoensis) on Tutuila Island, American SamoaJOURNAL OF ZOOLOGY, Issue 3 2001Anne P. Brooke Abstract The small population and limited range of the Samoan flying fox Pteropus samoensis has generated concern regarding the survival of this large, diurnally active bat. During 1995,96, surveys were conducted monthly in six study valleys on Tutuila Island, American Samoa, to assess population size. The amount of diurnal and nocturnal activity was investigated to gauge the accuracy of diurnal surveys, and territorial behaviours were observed to determine how they influenced local dispersion. Individuals showed long-term fidelity to a series of roosts and small core areas that were used both nocturnally and diurnally. Territorial defence was observed only of temporary feeding territories in fruiting or flowering trees. Bats defended food resources by aerial patrols and extended aerial chases in which intruders were frequently bitten. Foraging movements changed seasonally, with up to 80% of individuals observed bypassing study valleys. The mean density of bats observed within the study valleys was 6.1 bats/km2 (range = 0.9,18.5 bats/km2). Pteropus samoensis were active both nocturnally and diurnally with greatest activity in late afternoon and evening, 16:00,22:00. Because bats were most active at night, it is probable that daytime surveys of flying bats undercount the number of individuals present. Greatest densities were found in valleys that were contiguous with large tracts of forest inaccessible to people. Most observations of roosting bats were of solitary males on dead branches that jutted above the forest canopy, while females and dependant young roosted below the canopy, hidden within vegetation. Adult male,female pairs were rarely seen together other than during the mating period in August,January. The population has increased following a ban on hunting, but reliance on mature forest makes long-term species survival dependant on protection of the limited mature forest remaining and continued hunting restrictions. [source] Stress in Yucatan spider monkeys: effects of environmental conditions on fecal cortisol levels in wild and captive populationsANIMAL CONSERVATION, Issue 5 2009A. Rangel-Negrín Abstract In the Yucatán Peninsula, spider monkeys Ateles geoffroyi yucatanensis are generally found in two contrasting conditions: large tracts of conserved forest or small fragments surrounded by human populations. In the present study, we analyzed fecal cortisol levels of spider monkeys to investigate whether environmental conditions have an influence on stress; specifically, we compared fecal cortisol across individuals living in conserved forests, fragmented forests and captive conditions (zoos and pets). Radioimmunoanalysis of fecal samples from 121 individuals indicated significant differences in mean cortisol for A. g. yucatanensis based on habitat type, with the lowest levels found in the conserved forest condition. The higher cortisol levels in both fragmented forest populations and in captive individuals may be the result of metabolic and behavioral stress. The mean male fecal cortisol concentration was significantly higher than that of females, and the fecal cortisol concentration was higher in the dry season compared with the wet season in a conserved habitat. Therefore, we emphasize the importance of considering sex and seasonality when monitoring fecal cortisol concentrations of spider monkeys, and more generally of frugivores, as they face a seasonal variation in food availability. Finally, our results suggest that forest fragmentation may create long-term stressors for spider monkeys, affecting the viability of populations living under such conditions. [source] The conservation value for birds of cacao plantations with diverse planted shade in Tabasco, MexicoANIMAL CONSERVATION, Issue 2 2000Russell Greenberg We surveyed birds in cacao (Theobroma cacao) plantations in the state of Tabasco, Mexico. The shade canopy was planted by farmers and consisted of approximately 60 species of trees with no single dominant species. Canopy height averaged 15 m and the structure was multi-storied. We conducted 220 ten minute, 25 m radius point counts for birds and detected 1550 individuals from 81 species. The average number of birds/point and the expected diversity in a fixed number of individuals within the cacao surveyed were well within the range of other lowland habitats, including agricultural sites, that we have surveyed previously in neighbouring Chiapas. In the Tabascan cacao, the migrant group was composed, in part, of forest species, and dimorphic species were represented primarily by males, which in other areas are known to dominate forest or forest-like habitats. In contrast to the composition of migrant species, we found few resident forest specialists in Tabascan cacao. Instead, the tropical resident group was composed of large-bodied generalist species that use small patches of trees in open habitats. These results (moderate diversity, low numbers of forest specialists) differ from the few studies completed in ,rustic' cacao systems located near large tracts of forest. The planted shade cacao agroecosystem , at least in the absence of nearby forest , may have a limited value for conserving lost tropical forest bird diversity, but it provides habitat for woodland-associated migratory species. Our results also indicate that the planted shade cacao plantations supported few small omnivorous or frugivorous species, probably because cacao itself, as well as the dominant shade trees, produce primarily mammal or wind dispersed fruit and seeds. [source] Potential of Pakistani camel for dairy and other usesANIMAL SCIENCE JOURNAL, Issue 5 2007Muhammad YAQOOB ABSTRACT Camels have the potential for milk, meat and draught power and can contribute a handsome share of the production of these commodities. The potential of this wonderful animal has never been realized and it could be harnessed as a prospective milk producing animal. The future of animals that can thrive under harsh environmental conditions, the camel being at the top of the list, is bright. The camel is still a neglected species in Pakistan and has not received the proper attention of researchers and scientists. The population explosion, urbanization and industrialization have expanded agricultural activities to produce more food for the rapid growing human population of the country. Cultivated areas are shrinking, thus reducing the fodder production area for buffalo and cattle. Under these circumstances we have to search for other available sources to enhance milk production. The environmental changes occurring on the earth and the water shortage in the region have also adversely affected the production potential of buffalo, cattle, goats and sheep. Under these changing ecological circumstances, rearing camel is the best option for more milk production and the proper utilization of the vast unused lands of this country. Most studies also have named the camel as an animal of great socioeconomic importance in large tracts of the industrializing world. The camel serves as a cheaper source of power for drawing water from wells, plowing and leveling land, working mini extraction mills (extracting from oil seeds), grinding wheat, corn and other grains and crushing sugarcane and pulling carts for the transportation of goods as well as people. [source] WELFARE, ENTERPRISE, AND ABORIGINAL COMMUNITY: THE CASE OF THE WESTERN AUSTRALIAN KIMBERLEY REGION, 1968,96AUSTRALIAN ECONOMIC HISTORY REVIEW, Issue 3 2006Tony Smith Aboriginal; Australia; entrepreneurship; social policy This article traces the development of Aboriginal-controlled businesses and their ability to access land, labour, and finance in the Kimberley region of Western Australia. It investigates the influence of the development policies on Aboriginal commercial operations. Among other things, the implementation of a new policy , beginning in the early 1970s , saw the handing over by the state of large tracts of land, and the provision of labour and finance to Aboriginal interests. The article analyses the tension between land and enterprise as a welfare measure and as a means of commercial endeavour. [source] Partnering for Greater Success: Local Stakeholders and Research in Tropical Biology and ConservationBIOTROPICA, Issue 5 2009Karen A. Kainer ABSTRACT Local communities are important stakeholders in resource management and conservation efforts, particularly in the developing world. Although evidence is mixed in suggesting that these resident stakeholders are optimal forest stewards, it is highly unlikely that large tracts of tropical forests will be conserved without engaging local people who depend on them daily for their livelihoods. Stakeholders, who reside in biodiverse ecosystems like tropical forests, are the largest direct users and ultimate decision-makers of forest fate, can be important investors in conservation, harbor local ecological knowledge that complements Western science and frequently have long-term legitimate claims on lands where they reside. Research partnerships with local stakeholders can increase research relevance, enhance knowledge exchange and result in greater conservation success. Different phases of the research cycle present distinct opportunities for partnership, with flexibility in timing, approaches and strategies depending on researcher and local stakeholder needs and interests. Despite being the last step in the research process, dissemination of results can be the best starting point for researchers interested in experimenting with local stakeholder engagement. Still, tropical biologists might not choose to partner with local people because of lack of institutional rewards, insufficient training in stakeholder engagement, insecure research infrastructure in community settings, and time and funding limitations. Although not appropriate in all cases and despite significant challenges, some biological scientists and research institutions have successfully engaged local stakeholders in the research process, proving mutually beneficial for investigators and local people alike and resulting in important innovations in tropical biology and conservation. [source] | |||||||||||||