Quantifying patch distribution at multiple spatial scales: Applications to wildlife-habitat models

Multiscale analyses are widely employed for wildlife-habitat studies. In most cases, however, each scale is considered discrete and little emphasis is placed on incorporating or measuring the responses of wildlife to resources across multiple scales. We modeled the responses of three Arctic wildlife species to vegetative resources distributed at two spatial scales: patches and collections of patches aggregated across a regional area. We defined a patch as a single or homogeneous collection of pixels representing 1 of 10 unique vegetation types. We employed a spatial pattern technique, three-term local quadrat variance, to quantify the distribution of patches at a larger regional scale. We used the distance at which the variance for each of 10 vegetation types peaked to define a moving window for calculating the density of patches. When measures of vegetation patch and density were applied to resource selection functions, the most parsimonious models for wolves and grizzly bears included covariates recorded at both scales. Seasonal resource selection by caribou was best described using a model consisting of only regional scale covariates. Our results suggest that for some species and environments simple patch-scale models may not capture the full range of spatial variation in resources to which wildlife may respond. For mobile animals that range across heterogeneous areas we recommend selection models that integrate resources occurring at a number of spatial scales. Patch density is a simple technique for representing such higher-order spatial patterns.     

The Role of the Bark Beetle, Hylastes ater (Coleoptera: Scolytidae), as a Sapstain Fungi Vector to Pinus radiata Seedlings: A Crisis for the New Zealand Forestry Industry?

The role of the bark beetle Hylastes ater in the re-establishment of Pinus radiata forest in New Zealand is discussed. H. ater was found to be a dominant factor in seedlings mortality in the first year following planting. However, seedling mortality is usually relatively low. In contrast, it was found the large numbers of seedlings were sub-lethally damaged by H. ater feeding attempts, particularly in high risk sites. High risk sites were identified as sites that were harvested during March and April (autumn) when the peak flight activity of H. ater occurred, and subsequently planted with P. radiata seedlings the following winter. H. ater was found to vector sapstain fungi to seedlings during feeding attempts, and a strong relationship between the severity of damage and presence of sapstain fungi was identified. The role of H. ater as a vector of these fungi and the potential implications to the New Zealand forest industry are discussed.     

黑河(额济纳河)下游绿洲生态系统受损与生态保育对策的思考

额济纳绿洲是我国西北干旱区中心的一道生态防线。 2 0世纪后半世纪绿洲生态系统严重受损 ,景观结构急剧恶化 ,黑河的供水量逐年趋于下降 ,由 50年代的 1 2 .2 5亿 M3 下降到 90年代的 7.2 4亿 M3。地下水位也相应地降低 ,土地盐化也在加剧。胡扬与沙枣林面积由3 .45万公顷减少到 2 .2 0万公顷 ,并以老龄林为主。红柳灌丛也减少了 50 % ,并且多已成为稀疏矮化的群落。各种禾草草甸严重退化 ,多已演替成为苦豆子群落。为了维护我国西北的这一生态屏障 ,必须坚持以恢复与保护自然绿洲为主 ,恢复胡杨林、沙枣林及红柳灌丛的覆盖率 ;建立人工草地 ,改善土地覆盖 ,建设自然一人工复合绿洲。在绿洲建设与保育工程中必须保证充分供水 ,调控水盐动态 ,发挥生物一景观多样性的系统耦合效应 ,实现绿洲生态系统健康     

阿拉善荒漠特有珍稀濒危植物绵刺克隆生长构型研究

绵刺是阿拉善荒漠特有珍稀濒危植物 ,其具有独特的克隆生长构型 :由枝条下垂形成长间隔物的典型的游击型克隆生长构型和由根茎处形成的典型的密集型克隆生长构型。本文以环境塑造与克隆生长构型的可塑性关系研究绵刺的克隆生长构型 ,揭示其对环境表现出生态对策的高度适应性和可塑性     

Aversion of the feral pigeon and the house sparrow to pellets and sprouts treated with commercial formulations of methyl anthranilate

Two methyl anthranilate formulations, ReJex‐iT® TP‐40 and AG‐36, were tested as bird‐repelling agents for animal feed and vegetable sprouts, respectively. Feral pigeons (Columba livia) and house sparrows (Passer domesticus) are important pests of animal husbandry and field crops in Israel. In each 4‐day experiment, four birds were held together in an aviary, and were offered four trays or dishes with animal feed or cauliflower sprouts in four corners of the cage. The trays and dishes were transposed daily in a Latin square sequence. Pigeons consumed significantly more untreated feed than treated feed. When no alternative untreated food was offered, there was no significant repellency. Treatment of animal feed with TP‐40 to give 2.0 ml methyl anthranilate kg^?1 or less had no repellent effect on sparrows. Concentrations of 4.0 ml kg^?1 or more repelled the sparrows significantly. When no untreated feed was presented, pigeons and sparrows preferred the lowest concentration of methyl anthranilate presented. When AG‐36 was tested on vegetable sprouts, the sparrows tended significantly to avoid the highest concentration used—14.5 ml methyl anthranilate litre^?1 spray. The inter‐specific differences between the birds indicate that the efficacy of methyl anthranilate formulations as a repellent has to be specified for every species. This study did not determine (1) the possibility of developing habituation, (2) the behaviour of birds under natural conditions in the field, or (3) the influence of the feeding behaviour of a sympatric bird species on the repellency of methyl anthranilate to other species. © 2001 Society of Chemical Industry     

勒克瑙根结线虫居群对我国亚热带丝瓜的危害

通过田间对感根结虫病的丝瓜植株取样调查发现 ,勒克瑙根结线虫居群对中国亚热带地区丝瓜生产危害较大 ,受害面积占调查面积的30% ,减产25%以上。研究发现勒克瑙根结线虫居群危害丝瓜的原因是丝瓜属于勒克瑙根结线虫的寄生植物 ;防治勒克瑙根结线虫居群危害最有效、最经济的方法是利用勒克瑙根结线虫属专性植物寄生线虫的生物学特性 ,实行蔬菜品种轮作。     

水稻病虫为害损失试验初报

本文探讨了测算水稻病虫为害总损失、虫害损失、病害损失、挽回损失和实际损失等五组数据的田间试验设计和方法，并以此来评估水稻病虫为害损失情况，同时分析造成为害损失的病虫主次。     

模拟螟害对水稻产量影响的研究

设置了模拟螟害、氮肥和基本苗三因索随机区组试验。结果表明各因素对产量及其构成因素的影响都极显著。水稻9—15叶期,分别损失分蘖8%、20%、20%、4%、4%、1%、1%以上亩穗才显著减少,分别损失分蘖8%、20%、20%、12%、8%、4%、1%以上才显著减产。随着损失叶期和损失度增大,亩穗渐减,着粒数、实粒数和千粒重不同程度增加。12—14叶期,1%—2%的损失产量反而略提高。讨论了氮肥和基本苗对产量及其构成因素的影响,认为每亩(666.7m~2)施5kg 纯氮的氮肥、移栽3.428万棵苗/亩有利于高产。     

应用模糊聚类评价布氏田鼠为害等级

由于各地环境条件和布氏田鼠密度与种群分布格局的差异,其为害程度很难用统一的数量化指标加以评价,造成了准确测报该鼠为害水平的困难。本文试采用模糊聚类的方法,结合该鼠数量、分布格局以及多项环境因子的定性、定量指标加以综合分析,依其聚类结果可进行该鼠为害等级的全面评价,根据作者收集的20组数据的微机处理,表明这种方法可进行大区域不同环境条件下的为害等级评价,具有良好的应用前景。     

小地老虎为害棉苗缺株产量损失及棉株群体补偿力模拟试验

研究结果明确了模拟棉苗受小地老虎为害造成断苗缺株后，周围棉株有不同程度的补偿作用，主要表现在有效铃的增加和产量的提高，缺１株苗成铃能获得１０１．８５％的补偿，籽棉平均补偿率达８７．２４％，损失率为１２．７６％。但自连续缺２株以上，则补偿率下降为５０．６２％－３５．７５％，损失率上升为４９．３７％－６４．２４％。补偿量和损失量（率）是随缺株数的增加而增长，而补偿率则随缺株数增加而下降，在不同缺株数间