浅谈GPS技术和ArcGIS软件在林地勘验工作中的应用

随着科学技术的不断创新,信息手段已经渗透到各个领域,GPS技术和ArcGIS地理信息系统软件也应用于林业工作中,使得林业工作效率得到了极大的提高,林业工作者可以获取精确性更高的数据。文章主要介绍了GPS技术和ArcGIS地理信息系统软件在林地勘验工作中的应用及其优缺点,为以后的林地勘验工作所参考。     

Distances Walked by Long Established and Newcomer Horses in an Open Stable System in Northern Germany

Group housing is claimed to possibly provide horses with a species-appropriate movement possibility, and hence, better welfare. Thus, this study analyzed the daily walked distances of 51 horses held in one group in a “HIT Active Stable” (Hinrichs Innovation + Technik) in Northern Germany by using global positioning system (GPS) technology during a 7 ½-month time span. The daily walking distances of the whole group, as well as newcomers, were investigated. The horses traveled an average of 8.43 km/day. Linear mixed models were applied. The observation day had a significant effect on the daily walking distances (P < .01) due to season and the available area per horse. The age as covariate also had a significant effect (P < .01). The breed had no significant effect (P = .96). No significant differences were found in sex (P = .69), which can be explained by the fact that only mares and geldings were investigated, which do not show increasing locomotion caused by sexual behavior as stallions do. On six of the first nine days, new horses moved significantly more compared to the remaining 24 of the 30 observation days directly after individuals’ inclusion. This is probably due to more exploration and rank-fighting behavior. Similar walking distances were seen among the horses on the single observation days because all horses had to travel the same distance to reach resources. Further, it is suspected that not all horses can sufficiently live out their urges to move, especially in winter, when pasture is inaccessible.     

Integrating space and time: a case for phenological context in grazing studies and management

In water-limited landscapes, patterns in primary production are highly variable across space and time. Livestock grazing is a common agricultural practice worldwide and a concern is localized overuse of specific pasture resources that can exacerbate grass losses and soil erosion. On a research ranch in New Mexico with average annual rainfall of 217 mm, we demonstrate with a quantitative approach that annual seasons vary greatly and examine foraging patterns in Angus-Hereford (Bos taurus) cows. We define five seasonal stages based on MODIS NDVI: pre-greenup, greenup, peak green, drydown and dormant, and examine livestock movements in 2008. Daily distance traveled by cows was greater and foraging area expanded during periods with higher precipitation. A regression model including minimum NDVI, rainfall and their interaction explained 81% of the seasonal variation in distance traveled by cows (P<0.01). Cows explored about 81 ha·d⁻¹ while foraging, but tended to explore smaller areas as the pasture became greener (greenup and peak green stages). Cows foraged an average of 9.7 h daily and spent more time foraging with more concentrated search patterns as pastures became greener. Our findings suggest that phenological context can expand the capacity to compare and integrate findings, and facilitate meta-analyses of grazing studies conducted at different locations and times of year.     

GPS在定位和面积量测中的误差分析

以河南农业大学校区为研究区域,通过手持GPS仪探讨了不同观测时长、不同观测时间以及不同区域面积对GPS精密度和稳定性的影响。结果表明:不同观测时长对GPS定位的坐标没有影响;不同观测时段中,定位时长为60 s和120 s的稳定度相差不大,而实时定位的稳定度比120 s的稳定度高3倍以上;当地块面积在3 600 m2以下时,GPS测量结果的变化幅度较大,呈不稳定状态,当地块面积在3 600 m2以上时,GPS测量结果的变化幅度逐渐变小,呈现面积越大、误差越小、精度越高的趋势。     

GPS技术在森林资源连续清查中的应用

作者这几年一直在从事森林资源连续清查方面的有关工作,参加了整个西北森林资源监测地区有关省的森林资源连续清查国家级的检查验收工作,对GPS技术在森林资源连续清查中的应用做了一些研究和探讨。文章着重讨论了手持GPS接收机在森林资源连续清查中应用的主要方面以及应用时的一些优点和存在的问题、不足之处。     

林业工作中GPS功能简介

简单叙述了林业工作者在野外工作中,GPS全球定位系统导航仪所具有的定位、测距、测速、导向和卫星示踪等功能。     

GPS与CASS6．0、AutoCAD软件在景东县集体林权制度改革中的综合运用

为了解决景东县深化集体林权制度主体改革中时间紧、任务重、技术难度大、技术力量弱等实际问题,将GPS与CASS6．0、AutoCAD软件综合运用,使得外业工作速度加快,质量提高,每个技术员从一天只能勘查10～20宗林地提高到30～50宗林地,并且节省了人力、资金和时间,资料规范整齐,实现无纸化办公,档案管理方便．     

基于PDA的森林资源数据采集系统的设计与实现

为了实现森林资源数据采集的全程无纸化作业,提高数据采集效率,研究开发了基于个人数字处理助理（PDA）的森林资源数据采集系统。从系统开发平台与开发工具的选择、系统架构与功能、实现的关键技术等方面进行了详细的介绍;重点研究了客户端与服务器之间的无线网络模式下数据传输的交互技术;完成了系统服务器端、客户端的软件开发,并在最后调试运行了整个系统。     

几种测量方法在森林资源调查中的应用与精度分析

通过外业调查数据分析和理论推导,对林业调查中的几种测量方法进行了比较分析。研究表明：①罗盘仪由于制作粗糙,在标准样地测设中尚能满足规范要求,但随着距离和竖直角的增加,精度急剧下降,在大范围的林地面积和科研特殊需要的测量中操作不便捷,精度差,效率低;②全站仪测设样地边长不超过100 m时,半测回的距离测量可达到1/10 000,高差测量误差不超过1 cm,且受距离和竖直角的影响较小;③当面积大于3.34 hm^2,边长超过100 m时,手持全球定位系统（GPS）完全可代替罗盘仪,并可通过坐标差分或修正坐标转换参数来提高测量精度。另外,网络RTK的发展必将连同全站仪成为精准林业测量的主要仪器设备。     

GPS航向仪的研究

为了降低小型船舶安装导航设备的成本,设计了GPS航向仪,通过GARMIN GPS-12、Ashtech Z—Xtreme GPS两种型号5台GPS进行同时观测,共得到1500组观测数据,并对这些数据进行计算分析,分别得到两种型号GPS的实测航向,以验证航海型GPS用作航向指向系统的可行性。结果表明：航海型差分GPS的航向为141．4114°,航海型GPS航向的最大偏差为3．6227°。表明GPS航向仪完全可以满足航海上的需要。