Ideal Free Distributions of Mobile Pastoralists in Multiple Seasonal Grazing Areas
Abstract The pastoral system in the Far North Region of Cameroon is best described as an open system in which mobile pastoralists have open access to common-pool grazing resources. We hypothesized that there is a self-organizing management system of open access to common-pool grazing resources and predicted that we would find an Ideal Free Distribution (IFD) of mobile pastoralists within seasonal grazing areas. In this paper we used mobility data and remote sensing data from two seasonal grazing areas at the end of the dry season in three consecutive years to evaluate that hypothesis. We found evidence of an IFD in the two seasonal grazing areas of the Logone Floodplain and the Lake Maga area. These findings offer further support for our hypothesis that there is a complex adaptive system in which pastoralists distribute themselves effectively over available grazing resources.
Spatiotemporal dynamics of cattle behavior and resource selection patterns on East African rangelands: evidence from GPS-tracking
ABSTRACT Characterizing cattle behavior is crucial to inferring fine-scale resource selection patterns and improving rangeland management. However, our understanding of cattle behavior and resource selection on the extensive African rangelands suffers from a lack of quantitative, continuous and inter-seasonal monitoring of cattle movement. Based on integration of GPS-tracking and field observations, this study links cattle behavioral types with statistical parameters of movement, analyzes spatiotemporal dynamics of behavior and predicts resource selection patterns in Borana Zone of southern Ethiopia. We find that different cattle behavioral types were associated with distinct ranges of movement velocity. Distribution of identified cattle behavior varied substantially within the day and along the distance gradient from camp locations. Vegetation greenness, topography, study site, herding strategy and season were dominant factors influencing foraging areas selection by cattle. Research findings suggested that extensive herding through camp relocation can promote forage uptake while reducing energy spent on traveling. Future modeling of cattle resource selection needs to be based on longer-term GPS-tracking data and incorporate additional social, environmental, institutional and cultural factors to better interpret the complexity associated with cattle behavior in extensive grazing systems.
Genetic Effects of Acute and Chronic Ionizing Irradiation on Pinus sylvestrisL. Inhabiting the Chernobyl Meltdown Area
The main results of the 12-year radiation-genetic monitoring of radiobiological, cytogenetic, and genetic parameters in Pinus sylvestrisforest plantation from the Chernobyl meltdown area are presented. The acute ionizing irradiation at doses > 1 Gy was shown to induce formation of morphoses and depressed growth; at doses >2 Gy, the reproductive ability of the trees declined. The radiobiological parameters showed a linear or close to linear dose-dependence relationship. The acute irradiation at a dose of 0.5 Gy induced cytogenetic and genetic effects that were significantly higher than the corresponding control values. The relationship between the cytogenetic effects and the absorbed dose was exponential. The dependence of the mutation frequency at specific loci on the absorbed dose was described by a nonlinear curve. The results of cytogenetic analysis of seedlings obtained from seeds annually collected in zones of slight, moderate, and strong damage of Pinus sylvestrisL. are presented.