贵州草海斑头雁越冬觅食地选择

湿地生境可为水鸟提供保护场所、生存和繁殖所需要的能量以及种群延续的条件(Fretwell,1972;Heitmeyer,1980;Fredrickson,1981;Krapu,1981).生境的可利用性、分布和质量会影响越冬期水鸟的集群、活动、能量分配和繁殖过程(Fredrickson et al.,1979;Paulus,1980),同时会对水鸟的繁殖潜力造成影响(Miline,1976;Ankney,1977).生境选择通常会使生物分布非随机化,这是自然选择的结果(Southwood,1977;Martin,1998;Clark et al.,1999).这种非随机化分布方式的产生是由于生物体对环境因子具有选择性,即在相同生境中的随机区域选择位点进行测量,并将它们进行比较的结果(Wilson,1998).     

A site dependent top height growth model for hybrid aspen

In this study height growth models for hybrid aspen were developed using three growth equations. The mean age of the hybrid aspen was 21 years (range 15?51 years) with a mean stand density of 946 stems...     

Growth Response of Loblolly Pine (Pinus taeda L.) 3–5 Years After Plantation Establishment Using Different Management Intensities

The upward trend of intensive management in Southern pine forests is expected to continue, both in area and intensity level. Much of the Mississippi Lower Coastal Plain (LCP) is managed intensively using some combination of mechanical site preparation, chemical site preparation, and herbaceous weed control (HWC). We studied pine growth response and competition control on loblolly pine (Pinus taeda L.) plantations 3–5 years following establishment using five combinations of chemical site preparation, mechanical site preparation, and HWC. Treatments were designated a priori as 1 (least intensive) through 5 (most intensive) largely on the basis of anticipated impact on the vegetation community. We measured pine height and diameter at breast height (dbh); woody stem density; hardwood basal area (BA); coverage of herbaceous plants, understory woody plants, and pine trees; and estimated differences in pine response using age-shift calculations at age 5. Pine height and dbh were correlated with treatment intensity; treatment 5 maintained an average advantage of 1.4-m height and 2.5-cm dbh over treatment 2, the least responsive treatment. Woody stem density varied widely and was not affected by treatment; understory woody coverage was also unaffected by treatment. Coverage of herbaceous plants was reduced in treatments receiving broadcast HWC, and in treatment 2, where slower establishment of pines may have acted as a release for competing woody plants. Age-shift gains relative to treatment 2 ranged from 0.4–1.0 years. Based on year 5 measurements of hardwood BA, it is likely that treatments 1 and 2 will fall further behind treatments 3–5 as the stands mature. Greatest control of competing vegetation and maximum growth of pines was achieved with the most intensive treatment.     

Regional vegetation management standards for commercial pine plantations in South Africa

During the 1990s a number of trials were implemented in the summer rainfall region of South Africa to determine both the short- and long-term impacts of competing vegetation on pine growth. Trial sites were selected across different physiographic regions such that a range of altitudinal, climatic and environmental gradients were represented. Although the understanding gained from these trials allowed for the development of vegetation management standards, their operational and economic viability need to be tested on a commercial basis. Four pine trials were thus initiated to test the applicability of these standards when utilised on a commercial scale. Two of the trials were situated at lower-altitude sites (900 m and 1 000 m above sea level [asl]), one at a mid-altitude site (1 267 m asl), and one at a higher-altitude site (1 650 m asl). Several vegetation management treatments developed to suit the predicted vegetation load at each site were implemented and varied according to either weeding intensity (high, moderate and minimal), or the area around the tree that was kept free of vegetation (no vegetation control, a ring/row weeding and complete vegetation control). Tree growth up to 3.5 years was linked to the level of vegetation management in each treatment and its associated total cost for that time period, allowing for the development of different cost-benefit comparisons. The intensity of vegetation management required to produce significant growth benefits decreased with increasing altitude, as did the area that needed to be kept free from competing vegetation. In contrast to the higher-altitude site, where tree growth did not benefit from vegetation management, there was a 18, 25 and 112% increase in diameter growth for the high-intensity vegetation management operations relative to minimal or no vegetation control at the three mid- and lower-altitude sites. Besides demonstrating the commercial applicability of research results, this series of trials has shown that site-dependent vegetation management is viable on a commercial scale and will allow the South African forest industry to adjust their weed control budgets on a regional scale (linked to altitude).     

Diel movement of bullhead (Cottus perifretum) in a lowland stream

Abstract – Passive integrated transponder tags have been successfully applied in Cottus spp. and have enabled researchers to gather more information about the movement patterns of individual fish in the wild. In two succeeding years during springtime, a portable antenna was used to determine diel movements of bullhead (Cottus perifretum). In 2007, bullhead (N = 26) moved significantly farther distances at night (mean, 0.42 m·h^?1) and dawn (mean, 0.35 m·h^?1) than during daytime (mean, 0.11 m·h^?1; mixed model, P < 0.001, respectively; P = 0.001), which may be due to foraging activities for Gammarus spp. Irrespective of diel period, smaller fish covered significantly longer distances (P = 0.001). In 2008, similar diel movement patterns were observed, but the differentiation between daytime (mean, 0.12 m·h^?1) and night periods (mean, 0.18 m·h^?1) was not significant (mixed model, P = 0.087; N = 49 bullhead). It is discussed that longer tracking intervals used in 2008 (three times per 24‐h instead of every two hours) were not suitable to detect the sheer magnitude of distances covered during a diel period. It is shown that this may be due to ‘site fidelity’ of some individuals: after swimming several metres at night, they returned to the exact location they previously occupied during daytime. In 2008, sex and body size were not related to diel movement. The present study is the first to present a quantitative differentiation between diel distances covered in a Cottus spp.     

Relationship between site index of oriental spruce [Picea orientalis (L.) Link] and ecological variables in Maçka,Turkey

Abstract

Oriental spruce [Picea orientalis (L.) Link] is a species native to Turkey, covering about 350,000 ha. The species is of great importance to the production of timber as well as to the creation of social welfare in eastern Black Sea region. There are few studies about ecological variables affecting oriental spruce site productivity. Based on data from 90 sample plots, multiple regression models were developed using topographic, edaphic, soil nutrients, climatic subgroups and all factors integrated. Within the different subgroups of site factors, the integrated model with all ecological variables provided the best statistical results, which explained 77% of index variation. Other topographic, edaphic, soil nutrients and climatic subgroup models were enumerated by the success of modelling site index of oriental spruce from the related site variables. The results show that the integrated model is more successful than the models developed separately for each ecological variable. However, the integrated model included 12 different variables and thus the assessment of some of these model variables, e.g. element content of the soil (Ca²⁺, Mg²⁺, etc.), require potentially laborious soil analyses and costly applications. Therefore, the topographic model with only three variables (R ²=0.656), which can be assessed directly from digital maps by Geographical Information System (GIS), seems to be more promising and convenient, since the model can be easily applied to large areas. The results can be translated into practical recommendations to forest managers for selecting suitable site conditions for oriental spruce.     

成都十陵大遗址区域的保护与利用探究

通过对成都十陵遗址保护与利用的规划方法的探讨,探求解决城市边缘区大遗址保护与城市自身发展间矛盾的适宜思路,以期为今后的城市边缘区大遗址的保护与利用规划工作开拓思路。     

基于哑变量的木荷人工林树皮厚度模型研究

在木荷人工林中,基于哑变量模型法构建树皮厚度模型,以提高预测模型参数的稳定性,为木荷人工林出材率计算和经济价值评估方面提供参考依据。基于福建省南平市213块木荷人工林固定样地的调查数据,选取19个包含胸高处、任意高度处、相对树皮厚度和去皮直径的理论方程作为构建木荷人工林树皮厚度的基础模型,使用R软件进行模型拟合分析,运用决定系数（R²）、均方根误差（E_rms）、和方差（E_ss）、赤池信息准则（AIC）、贝叶斯准则（BIC）等模型评价指标,结合含熵值的TOPSIS法筛选出拟合度较高的4个基础模型（M1、M10、M12、M16）,进一步构建含龄组和立地质量哑变量的木荷人工林树皮厚度模型。用于建模的胸高处样本数为130个,任意高度处、相对树皮厚度和去皮直径样本数为2386个,用于检验模型拟合效果相对应的样本数分别为55个和1013个。结果表明：含龄组哑变量胸高处、任意高度处、相对树皮厚度模型（M20、M22、M25）的R²分别为0.9769、0.9214、0.9111,比基础模型（M1、M10、M12）的R²（分别为0.6981、0.5540、0.5056）提高了39.9%、66.3%、80.2%,有了明显提升;含龄组哑变量去皮直径模型M27的AIC为21.62,BIC为76.44,比其基础模型M16分别降低了95.8%、85.46%。通过含熵值的TOPSIS法对模型指标综合评价,并经模型配对t检验,这4个含龄组哑变量模型（M20、M22、M25、M27）拟合效果更佳,适合于福建木荷人工林树皮厚度预测。     

大红菇出菇特性研究

为深入了解大红菇的出菇特性，课题组从2008年5月开始，在景洪市大渡岗乡林场与当地政府和相关部门合作，建立了红菇实验基地，通过在出菇林地固定样地的定位监测和同步的气象观测。对红菇出菇、生长与植被、土壤、小气候、菌塘发育的相互关系进行了观察分析研究。初步探明了红菇出菇特性及生长发育过程，从而也为红菇保护促繁技术的研究和应用奠定了良好基础。