Daily Movements, Space Use, and Habitat Selection of GPS-tagged Northern Bobwhite in Texas
WILDLIFE SOCIETY BULLETIN
Authors: Cohen, Bradley S.; Marquardt, Dean D.; Bakner, Nicholas W.; Perez, Robert M.; Collier, Bret A.
Detailed information on movements, space use, and habitat selection patterns by northern bobwhite (Colinus virginianus; hereafter, bobwhite) is important for understanding population dynamics, gene flow, disease spread, and development of habitat management activities. Advances in Global Positioning System (GPS) technology has allowed researchers to collect spatial and temporal location data with increasing accuracy, which in turn has shifted the resolution at which habitat evaluations and management focus can occur. Only recently have GPS tags been deployable for small ground-nesting birds. We conducted a preliminary examination of the spatial ecology of 74 bobwhites equipped with GPS tags during breeding and covey season on 3 private properties in north-central Texas, USA, during 2015-2017. Specifically, we derived daily estimates of core area and range size using dynamic Brownian bridge movement models, daily distance traveled, and distance between consecutive roost sites. Bobwhites tended to move more during breeding than covey season. Consecutive roost sites were, on average, approximately 130 m apart. Daily core area and home range size of bobwhites across the calendar year were 1.99 +/- 0.13 and 6.29 +/- 0.85 ha, respectively. During the breeding season, bobwhites avoided hardwood communities and showed no selection or avoidance of shrub, grass, and herbaceous communities. During covey season, bobwhites selected for herbaceous, grass, and hardwood communities, and neither selected nor avoided shrub communities. Global Positioning System data on a variety of species has become the primary information used for habitat and conservation management decisions, therefore, future research on bobwhite will include the application of GPS, which our results show can increase the temporal resolution of information and be used for habitat conservation and restoration actions. (c) 2020 The Wildlife Society.
Spatiotemporal variations in soil organic carbon and their drivers in southeastern China during 1981-2011
SOIL & TILLAGE RESEARCH
Authors: Xie, Enze; Zhang, Yanxia; Huang, Biao; Zhao, Yongcun; Shi, Xuezheng; Hu, Wenyou; Qu, Mingkai
Understanding the spatiotemporal distribution of soil organic carbon (SOC) and its controlling factors is extremely important for improving soil quality and developing sustainable management practices. We quantified spatiotemporal variations in SOC in three typical regions (Shuyang, Rugao, and Shanghai) in southeastern China during 1981-2011, by using geographically weighted regression (GWR), and explored the drivers with a geographical detector method. A total of 219 topsoil samples were collected in the three regions to measure the SOC in 2011, and a total of 109 SOC data for 1981 were obtained from the soil survey reports of Shuyang, Rugao, and Shanghai, which involved in the database of the second national soil survey of China. The results showed that the mean SOC contents in 2011 were 14.68 g kg(-1), 9.55 g kg(-1), and 18.00 g kg(-1) in Shuyang, Rugao, and Shanghai, respectively. The topography (q = 0.60) and the sand content of the soil (q = 0.70) were the main drivers of the spatial variability in the SOC in Shuyang and Rugao, while the carbon inputs (q = 0.68) predominantly explained the spatial heterogeneity of the SOC in Shanghai. Significant increases in SOC storage occurred in Shuyang and Rugao from 1981 to 2011, with increase rates of 0.55 t ha(-1) yr(-1) and 0.26 t ha(-1) yr(-1), respectively. Land use change (dryland farming to rice cultivation) was identified as the largest driver of the SOC increases in Shuyang and Rugao (q values of 0.16 and 0.09, respectively), followed by increasing carbon inputs (0.14 and 0.07). However, the SOC storage in Shanghai rapidly decreased at a rate of -0.38 t ha(-1) yr(-1) during 1981-2011. The land use change from wetlands to rice cultivation was the primary reason for the decreasing SOC (q = 0.24), and a net decrease in carbon inputs between 1981 and 2011 was another main driver of the reduction in the SOC in Shanghai (q = 0.14). Our results from this study provide important information on the spatiotemporal changes in SOC and its drivers to the scientific community and decision-makers, for the development of management strategies to sustain soil fertility in many areas with rapid economic development and increasing populations.