Introduction Of Domestic Livestock Research Articles

Palaeoenvironmental conditions of the Palaeolithic–Neolithic transition in the Fergana Valley (Central Asia) – New data inferred from fossil mollusсs in Obishir-V rockshelter (Kyrgyzstan)

In the Fergana Valley and the surrounding territories, the number of archaeological sites increased during the Early Holocene. The coincidence of this cultural event, represented by the Obishirian archaeological unit with the onset of the Holocene, suggests that this growing intensity of human activity was driven by climate change, in particular warming and/or wetting. To test this hypothesis, we used fossil terrestrial molluscs from Obishir-V, the eponymic Obishirian site in southern Kyrgyzstan, as a proxy of palaeoenvironmental conditions. We studied pre-Obishirian loess-like deposits from the final Pleistocene and the Early–Middle Holocene sequence of Obishirian-bearing deposits. We analysed taxonomic composition of the mollusc assemblages and used it to infer palaeoecological characteristics, namely preferences in temperature and humidity as well as in differing habitats. Our results showed that the palaeolandscapes and the vegetation during the accumulation of the studied deposits remained almost unchanged. The mollusc assemblages reveal constant dry and warm climatic conditions and stable steppe-like vegetation. Our observations of rather stable climatic conditions in the Fergana Valley during the Pleistocene–Holocene turnover suggests that climate was only a minor driver of the rapid demographic change in Central Asia during those times. Some other factors beyond the changes of humidity must have played an important role. On the basis of our data derived from fossil mollusc assemblages at Obishir-V, we propose to consider the hypothesis that the factor responsible for the intense human occupation of the Fergana Valley during the Early Holocene had not an environmental, but rather a cultural background, such as the neolithization process, such as introduction of domestic livestock.

Efecto de los gradientes de pastoreo ovino sobre la vegetación y el suelo en Península Valdés, Patagonia Argentina

The introduction of domestic livestock in the arid Patagonia produced changes in vegetation and soil that altered fundamental ecosystem processes, increasing desertification and biodiversity loss. In this region, it is common to observe gradients of decreasing animal activity from watering points where livestock impact is greatest near the watering sites, called piospheres, particularly suitable for assessing the effect of grazing on arid ecosystems. The aim of this study was to evaluate the effect of sheep-grazing intensity using piospheres on the structure of the vegetation and soil in shrubby steppes of Peninsula Valdes, Argentina. Variation of plant cover, vertical complexity of the vegetation, number and area of vegetated patches, micro-topography and soil compaction in relation to piosphere gradients were studied using Generalized Linear Mixed Models (GLMM) and multivariate analyses. Grazing intensity decreased according to increasing distance to the watering point. This fact, explaining more than 50% of the overall environmental variability, confirmed the existence of a piosphere gradient on each studied site. Such environmental changes were characterized by a gradual increase in grass and litter cover, vertical complexity of vegetation and soil microtopography at increasing distances from the watering point. Percentages of bare soil and gravel, cover of annual grasses and soil compaction showed the opposite pattern. This study demonstrates, for the first time, the existence of sheep piospheres in the shrubby steppes of Peninsula Valdes. Our results indicate that sheep-grazing intensity is associated with changes in the structure and composition of the vegetation and the soil characteristics that are compatible with degradation processes in the study region. Taking into account the importance of Peninsula Valdes in the context of biodiversity conservation, more studies of this type are required to implement effective management actions integrating livestock and conservation efforts on the terrestrial ecosystems of the region.

HISTORICAL DISTRIBUTION OF DESERT BIGHORN SHEEP (OVIS CANADENSIS MEXICANA) IN COAHUILA, MEXICO

Abstract Historically, desert bighorn sheep occurred throughout Coahuila, Mexico, as far south as latitude 25°43′02″N. The subspecies Ovis canadensis mexicana probably was extirpated in Coahuila by 1970. We determined the historical range of desert bighorn sheep through a review of the available literature, interviews with long-term local residents, and a subjective habitat assessment. We found historical documentation of bighorn sheep in 14 mountain ranges (Sierra Alamitos, Sierra Maderas del Carmen, Sierra la Encantada, Sierra Hechiceros, Sierra del Pino, Sierra Mojada, Sierra el Rey, Sierra San Marcos y del Pino, Sierra Gavia, and Sierra la Paila), including 4 previously not recorded (Sierra el Fuste, Sierra el Almagre, Sierra de la Madera, and Sierra la Fragua). In addition, one archaeological site with remains of bighorn sheep was identified (La Candelaria Cave). The introduction of domestic livestock, particularly sheep and goats, and unregulated hunting probably were the major factors contributing ...

Sustainable Rangeland Grazing in Norse Faroe

The introduction of domestic livestock, particularly sheep, and rangeland grazing by Norse settlers to Faroe during the ninth century has generally been described as a major pressure on a sensitive landscape, leading to rapid and widespread vegetation change and contributing to land degradation. This view has, however, been developed without consideration of Norse grazing management practices which may have served to minimize grazing impacts on landscapes as well as sustaining and enhancing vegetation and livestock productivity. These alternative scenarios are considered using a historical grazing management simulation model with Faroese climate and vegetation inputs and given archaeological, historical and palaeoenvironmental parameters. Three contrasting rangeland areas are investigated and, based on the maximum number of ewe/lamb pairs the rangeland could sustain, modeling suggests that utilizable biomass declined with the onset of grazing activity, but not to a level that would cause major changes in vegetation cover or contribute to soil erosion even under climatically determined poor growth conditions. When rangeland areas partitioned into what are termed hagi and partir are modeled, grazing levels are still within rangeland carrying capacities, but productivities are variable. Some rangeland areas increase biomass and livestock productivities and biomass utilization rates while other rangeland areas that were too finely partitioned were likely to suffer substantial decline in livestock productivity. Partitioning of rangeland is a likely contributor to long-term differentiation of landscapes and the relative success of settlements across Faroe beyond the Norse period.

Fire History and Western Juniper Encroachment in Sagebrush Steppe

The recent expansion of juniper into sagebrush steppe communities throughout the semiarid Intermountain West is most frequently attributed to the reduced role of fire, introduction and overstocking of domestic livestock in the late 1800s, and mild and wet climate conditions around the turn of the century. This hypothesis has, however, limited quantitative support. There are few studies of fire history in the sagebrush steppe and none that examine the chronosequence of changes in mean fire intervals, introduction of livestock, and coincident climatic conditions with the initiation of post-settlement juniper expansion. This study was undertaken to test the hypothesis that the postsettlement expansion of juniper was synchronous with the introduction of domestic livestock, reduction in fire frequency, and optimal climate conditions for plant growth. We documented the fire history and western juniper (Juniperus occidentalis Hook). woodland chronology for a sagebrush steppe in a 5,000 ha watershed in south central Oregon. Regional tree ring data were used as proxy data for presettlement climatic conditions. Western juniper age distribution was determined by coring trees across the study area. Fire history was constructed from several small clusters of presettlement ponderosa pine (Pinus ponderosa Laws.) scattered across the study area. Samples were crossdated to determine fire occurrence to the calendar year. Mean fire intervals were computed for each cluster based on cumulative fire history of each tree sampled within the cluster. Fire events in low sagebrush (Artemisia arbuscula Nutt.) were documented by determining death dates of fire-killed western juniper trees. Records dating the introduction and buildup of livestock during the late 1800s and dates of initial fire suppression were summarized. Western juniper expansion began between 1875 and 1885, with peak expansion rates occurring between 1905 and 1925. The fire record spans 1601 to 1996. Before 1897, mean fire intervals within individual clusters ranged from 12 to 15 years with years between fires varying between 3 to 28. Nearly one third of the fires in the basin were large and usually proceeded by one year of above-average tree ring growth. Two fire events were recorded in the sparsely vegetated low sagebrush site, 1717 and 1855. The last large fire occurred in the study area in 1870 and the last small fire in 1897. The time sequence of wet climatic conditions between 1870 and 1915, introduction of livestock, and the reduced role of fire support the hypothesis that these factors contributed to the postsettlement expansions of western juniper.

A Viewpoint: Rangeland Health and Mule Deer Habitat

The Lassen interstate mule deer (Odocoileus hemionus) herd ranges from the northwestern area of Nevada to the northeastern corner of California along the western rim of the Great Basin. This mule deer herd serves as a model for what has happened in terms of population dynamics for many Intermountain west mule deer populations. Before contact with Europeans the populations were apparently very restricted. After the introduction of domestic livestock there has been significant impacts on the relative abundance of shrubs versus perennial grasses. Mule deer herds underwent tremendous expansion which peaked in the 1950s. Recent mule deer population numbers in the Lassen interstate herd have sharply declined. These population dynamics can be related to several habitat changes that reflect increased frequencies of wildfires in lower elevational sites as shrubs became old and decadent. Lack of fire in the higher elevations resulted in decadent/senscent old shrub stands. Invasion by exotic annual grasses in lower elevational sites. In certain environments, sharply improved range condition due to grazing management systems. The increase in coniferous woodlands, which may reflect changes in climate and/or atmospheric gases, combined with the lack of fire significantly negatively impact the Lassen Interstate mule deer herd. Identifying the specific aspect of winter, transitional, and/or summer habitat, in terms of dietary deficiency, that are most closely related to the decline in mule deer numbers is a highly significant problem facing wildlife and range managers.

The influence of habitat structure on arthropod diversity in Argentine semi‐arid Chaco forest

Abstract. The Argentine Chaco is a mosaic of grassland and open forest habitats maintained by natural disturbance activities such as fire. Since the introduction of domestic livestock and other human activities, the balance of this mosaic has been significantly altered, both in plant species and structural composition. This study focuses on the impact of such changes on the diversity of ground‐dwelling arthropods within semi‐arid Chaco forest. Quantitative measures of habitat structure and arthropod diversity were taken in forest areas previously subjected to grazing, logging and ploughing. Results indicated that arthropod diversity was smaller on sites with reduced structural complexity, with marked changes in arthropod family composition. The habitat components relating to plant architectural and vertical diversity were particularly influential on arthropod diversity. The guild size ratio of predatory to non‐predatory arthropods also differed significantly between habitats suggesting a change in the resource base available to some groups. The latter suggests a shift in the functional organisation of the forest ecosystem which could have important repercussions for the diversity of other trophic levels.

Defoliation regrowth and dry matter partitioning in the two arid zone grasses, Aristida armata and Thyridolepis mitchelliana

Plants of the desirable rangeland grass, Thyridolepis mitchelliana, and its undesirable companion, Aristida armata, were defoliated at various ages, and their subsequent regrowth and seed production compared with that of intact plants. Young plants of T. mitchelliana, but not A. armata, often failed to survive severe defoliation. Seed production by A. armata greatly exceeded that of T. mitchelliana and was much less affected by defoliation. In both defoliated and intact plants, the proportion of dry matter in inflorescences was several times greater for A. armata than T. mitchelliana, but the reverse occurred with leaf production. Root growth was little affected by defoliation, and there was no evidence of export of root material to support tops regrowth. Total plant production of both species was unaffected by the loss of half the tops, but was depressed by more severe defoliation. The differences between the two species in their reaction to defoliation seem sufficient to explain the displacement of T. mitchelliana by A. armata which followed the introduction of domestic livestock. Under grazing, A. armata is likely to have a reproductive advantage, and the implications of this for pasture management are examined.

The Effects of Different Forms of Land Use on the Ecology of a Semi-Arid Region in South-Eastern Rhodesia

Natural vegetation in the drier parts of Africa probably evolved under light utilization by shifting populations of indigenous herbivores. The pattern and intensity of utilization have changed since the introduction of domestic livestock although, prior to colonization by the white man, utilization remained light because both human and domestic animal populations were small and the African tribesmen were nomadic (Maloiy & Heady 1965). The recent rapid increase in human and livestock populations (Casebeer 1968; Hornby 1968) has led to serious and extensive damage over large tracts of land. In Rhodesia, over-utilization of vegetation began shortly after 1914 and by 1966 some 490% of the Tribal Trust Lands (where there is communal ownership of land) were either overgrazed or had very little herbaceous cover (Cleghorn 1966). Some of the most badly degraded of these areas are in the south-eastern 'lowveld' of Rhodesia. The term 'lowveld' denotes the hot, semi-arid regions of tree/bush savanna, below an altitude of c. 800 m, in which extensive livestock ranching is the main form of land use. The natural vegetation is generally the only source of food for livestock and, by virtue of its cover, it is vital for the conservation of soil and water resources. The area is too dry for planted pastures and improvement of the protective cover and forage value of the range must be achieved by manipulating the natural vegetation. The aim of this study, made in 1970-2, was to determine the composition, trends in composition and primary productivity of an area of lowveld vegetation in which different forms of land use were being applied, and to establish key factors in its ecology. The emphasis has been on overall interrelationships of the vegetation, rather than on detailed studies of particular aspects. In order to reduce inter-site variability, the study was restricted to basalt-derived soils.