Threshold responses of songbirds to long-term timber management on an active industrial forest

Forest managers often seek to balance economic benefits from timber harvesting with maintenance of habitat for wildlife, ecosystem function, and human uses. Most research on the relationship between avian abundance and active timber management has been short-term, lasting one to two years, creating the need to investigate long-term avian responses and to identify harvest thresholds when a small change in habitat results in a disproportionate response in relative abundance and nest success. Our objectives were to identify trends in relative abundance and nest success and to identify landscape-scale disturbance thresholds for avian species and habitat guilds in response to a variety of harvest treatments (clear-cuts, heavy and light partial harvests) over 14 years. We conducted point counts and monitored nests at an industrial forest in the central Appalachians of West Virginia during 1996-1998, 2001-2003, and 2007-2009. Early successional species increased in relative abundance across all three time periods, whereas interior-edge and forest-interior guilds peaked in relative abundance mid-study after which the forest-interior guild declined. Of 41 species with >10 detections, four (10%) declined significantly, 13 (32%) increased significantly (only three species among all periods), and 9 (22%) peaked in abundance mid-study (over the entire study period, four species had no significant change in abundance, four declined, and one increased). Based on piecewise linear models, forest-interior and interior-edge guilds’ relative abundance harvest thresholds were 28% total harvests (all harvests combined), 10% clear-cut harvests, and 18% light partial harvests, after which abundances declined. Harvest thresholds for the early successional guild were 42% total harvests, 11% clear-cut harvest, and 10% light partial harvests, and relative abundances increased after surpassing thresholds albeit at a reduced rate of increase after the clear-cut threshold. Threshold confidence intervals for individual species overlapped their guild threshold intervals 91% of the time. Even though relative abundance of most species (80%) did not decline as the area affected by timber management increased, implementing management at or below our approximate forest-interior and interior-edge harvest thresholds would reduce the number of declining species by half, maintain higher relative abundances of four species with a net decline in abundance but that peaked in abundance mid-study, and maintain higher relative abundances of ten additional species. In contrast, this management strategy also would prevent the increase in relative abundance of seven species and limit the increase in abundance of three species that increased throughout the study.     

Prediction of Rock Burst using the Method of Optimal Relative Membership Degree Based on the Maximum Entropy Principle

In the analysis of rock burst criterion prediction at home and abroad, the prediction standards of rock burst are selected including the conditions of mechanics、integrity、energy and brittle. The concept of relative membership degree on the rock burst prediction was introduced. The weight of standards and fuzzy matrix of relative membership degree are calculated. Uncertainty in rock burst prediction is described and compared according to the information entropy. Generalized weighted distance is also defined to characterize the differences in rock burst based on the maximum entropy principle, the establishment of a rock burst prediction fuzzy optimization model. The results from the application to practical example and comparisons with other methods are fairly good. Finally, the prediction model is applied in Putaoshan tunnel and the predictions are consistent with the actual rock burst.     

我国粮食产量影响因素的通径分析

通过通径分析,认为单产与化肥施用量是影响我国粮食总产量的主要因素。应通过科技进步与精耕细作来增加粮食产量。     

物料在锤片式粉碎机中的运动分析

本文论述了镜片式粉碎机中物料的运动规律。通过物料的运动分析求出物料的运动参数与物料在粉碎室内移动的关系，从理论上解释了锤式粉碎机生产率偏低、功耗大的毛病，从而为正确使用粉碎机、正确设计锤式粉碎机提供了理论根据。     

土壤养分系统研究在平衡施肥中的应用

应用土壤养分系统研究法对临猗潮土和柳林栗褐土进行了研究 ,表明该方法应用效果良好 ,可以比较全面地反映土壤养分状况 ,指示田间试验的养分限制因子 ,提高试验的准确性 ,为测土施肥和推广平衡施肥提供理论依据     

粒用菜豆种质资源芽期抗旱性研究

对６１５份粒用菜豆资源采用蔗糖高渗溶液鉴定法，筛选出高度抗旱优异资源１４份，对不同省（区）资源的抗旱性分布及优异资源的生物学性状进行了论述，阐明了抗旱性与生态环境及性状间的关系。     

秦冠和富士苹果果实成熟过程中的质地变化特性

对秦冠与富士苹果成熟过程中影响其硬度变化的部分因素如果肉细胞壁多糖、淀粉含量及相对电导率等的变化进行了初步研究。结果表明,共价结合果胶、纤维素及细胞壁含量的下降和半纤维素1类的上升与秦冠硬度的变化关系最密切,而与富士最相关的是半纤维素2类及细胞壁含量的下降和半纤维素1类、相对电导率及水溶性果胶的升高。另外,两者细胞壁、半纤维素和淀粉的初始含量就有显著差异。以上这些差异共同导致了秦冠和富士成熟过程中硬度的差异。     

黄瓜早熟育种中数量性状间相关及遗传分析

选用差异较大的黄瓜纯系,研究了14个农艺性状和生理生化性状之间的相互关系。2年的试验表明:早期产量同各农艺性状问表型相关、遗传相关、环境相关的方向、大小不尽一致;第1雌花节位、座果率、营养生长期同其它农艺性状间遗传关系最为密切,乙烯释放量是对其它性状间接选择的重要生化指标;不同性状的遗传变异系数、遗传力、相对遗传进度差异极大;乙烯释放量、单株雌花数、雌花节率、座果数、叶面积指数等是黄瓜早熟育种中较理想的副性状。     

甘蓝型油菜抗寒性的形态生理学研究

本试验研究了甘蓝型油菜抗寒性的形态生理学基础,分析了抗寒性与若干影响因子之间的关系,并用数学分析方法综合评价抗寒性,以确定有关因子对抗寒性的相对重要性。结果表明,甘蓝型油菜的抗寒性与外界温度(最低气温)相关密切,它主要通过对抗寒性生理基础的影响来实现的。在这些生理因子中,水分状况尤其是自由水和束缚水含量,与抗寒性关系密切;其次是细胞汁浓度和可溶性糖含量。光合作用和呼吸作用也与抗寒性有关。     

中水处理对植物叶片质膜透性及丙二醛含量的影响

本文研究中水处理对三角梅和凤凰木叶片质膜透性及丙二醛含量的影响.结果表明:三角梅叶相对电导率经50%浓度中水处理后达最高,而经100%浓度处理后,其相对电导率却略低对照;凤凰木叶相对电导率经100%浓度中水处理后达最高,而经50%中水处理后其相对电导率最低.不同浓度中水处理中,三角梅叶的丙二醛(MDA)含量在50%浓度中水处理下较高,而在100%浓度中水处理下其丙二醛含量与对照相差不大,略高于对照.凤凰木中丙二醛含量也是50%浓度中水处理后达最高,所不同的是,经100%浓度处理后略低于对照.