Academic literature on the topic 'Drift fence data'

Fencing wildlife populations can aid wildlife management goals, but potential benefits may not always outweigh costs of confinement. Population isolation can erode genetic diversity and lead to the accumulation of inbreeding, reducing viability and limiting adaptive potential. We used microsatellite and mitochondrial DNA data collected from 640 white-tailed deer confined within a 1184 ha fence to quantify changes in genetic diversity and inbreeding over the first 12 years of confinement. Genetic diversity was sustained over the course of the study, remaining comparable to unconfined white-tailed deer populations. Uneroded genetic diversity suggests that genetic drift is mitigated by a low level of gene flow, which supports field observations that the fence is not completely impermeable. In year 9 of the study, we observed an unexpected influx of mtDNA diversity and drop in inbreeding as measured by FIS. A male harvest restriction imposed that year increased male survival, and more diverse mating may have contributed to the inbreeding reduction and temporary genetic diversity boost we observed. These data add to our understanding of the long-term impacts of fences on wildlife, but also highlight the importance of continued monitoring of confined populations.

AbstractHistorically, there has been considerable interest in establishing the relationship between wind-blown snow flux (Q) and wind speed. By monitoring the drift growth at snow fences in Arctic Alaska during three winters, we computedQfor 36 distinct transport events. Each fence was instrumented with depth sounders to measure deposition rates. The majority of events (31) occurred between November and February, despite winter extending from October to June. On average, five substantial snow deposition events (SDEs) occurred at each fence per winter. The mean flux during SDEs was 0.16, 0.19 and 0.29 kg s−1m−1at Barrow, Imnavait Creek and Franklin Bluffs, respectively, the differences inQexplained by the different wind regimes at the three sites. To place these flux measurements in perspective, we reviewed all previous experimental values ofQ, with special attention to height and time over which the fluxes were measured. The new data help fill a range of wind speeds (12–18 m s−1) where prior results have been sparse. Combined, the full data define a diffuse cloud best represented by upper and lower bounding equationsQU= 1.3 × 10−3w2.5andQL= 3.3 × 10−9w6.5, wherewis wind speed (>5 m s−1). We suggest that these bounds, rather than a single equation, provide the best way to estimate snow fluxes.

Highlights Drift data collected from herbicide applications for corn, soybean, and cotton, including three commercial producers. Drift volumes and drift distances were estimated and correlated to wind speed, boom length, spray height, tractor speed, and droplet size (DV50). Boom length and spray height appear to be the dominant parameters affecting drift volume and drift distance, respectively. The results show a three- to fourfold reduction in drift using a hooded sprayer or spraying in calm weather. Abstract. Although several best practices are available, there are still opportunities to mitigate off-target pesticide drift, protect nearby sensitive crops, and address health concerns for humans/animals. The purpose of the study is to identify opportunities to mitigate drift from ground-based preemergent herbicide applications. Seven herbicide applications were tested for corn, soybean and cotton, including three regional commercial producers. Drift data were collected using water sensitive cards. ImageJ was used to analyze the droplet spectrum. Drift volumes and drift distances were estimated for each experiment. Data collected on wind speed, boom length, spray height, tractor speed, droplet size (DV50), and chemical application rate were used as explanatory variables of drift volume and drift distance. Individual and multiple linear regressions (MLRs) were carried out between drift volume, drift distance, and the explanatory variables. Our results show a three- to fourfold reduction in drift using a hooded sprayer or spraying in calm weather. Boom length and spray height appear to be the dominant parameters affecting drift volume and drift distance, respectively. The MLR results suggest that we can estimate drift (a) volume reasonably using a combination of boom length, DV50, and tractor speed and (b) distance reliably using a combination of spray height, boom length, and DV50. Keywords: Drift distance, Droplet spectrum, Fence board, Herbicide drift, Hooded sprayer, Preemergent herbicide, Water sensitive card.

Indigenous peoples of Canada’s North have long made use of boreal forest products, with wooden drift fences to direct caribou movement towards kill sites as unique examples. Caribou fences are of archaeological and ecological significance, yet sparsely distributed and increasingly at risk to wildfire. Costly remote field logistics requires efficient prior fence verification and rapid on-site documentation of structure and landscape context. Unmanned aerial vehicle (UAV) and very high-resolution (VHR) satellite imagery were used for detailed site recording and detection of coarse woody debris (CWD) objects under challenging Subarctic alpine woodlands conditions. UAVs enabled discovery of previously unknown wooden structures and revealed extensive use of CWD (n = 1745, total length = 2682 m, total volume = 16.7 m3). The methodology detected CWD objects much smaller than previously reported in remote sensing literature (mean 1.5 m long, 0.09 m wide), substantiating a high spatial resolution requirement for detection. Structurally, the fences were not uniformly left on the landscape. Permafrost patterned ground combined with small CWD contributions at the pixel level complicated identification through VHR data sets. UAV outputs significantly enriched field techniques and supported a deeper understanding of caribou fences as a hunting technology, and they will aid ongoing archaeological interpretation and time-series comparisons of change agents.