Statewide modeling of bobcat, Lynx rufus, habitat in Illinois, USA

We used sighting location and remotely sensed habitat data, multivariate statistical techniques, and a geographic information system to model bobcat (Lynx rufus) habitat in Illinois, thereby providing state wildlife managers with information to review the listing of bobcats as a state-threatened species and contribute to the development of a statewide management plan. We used canonical discriminant function analysis to model presence/absence and relative abundance of bobcats statewide. These models suggested that bobcats occurred in moderate to high abundance in 23 of 98 counties statewide (23%). We used stepwise logistic regression (SLR) analysis to model statewide habitat suitability. Spatial modeling of the SLR equation predicted that 29% of Illinois contained suitable habitat classified as P>0.50. Models were accurate when validated with an independent data set and indicated the importance of woods-related habitat variables to bobcats. In conclusion, these models provided tools to rapidly assess status that contributed to delisting bobcats as a threatened species in Illinois and provided further information to guide conservation efforts.     

Outcomes of longterm deciduous forest restoration in southwestern Ontario, Canada

At present, forest cover in southwestern Ontario, Canada, remains at less than 5% due to intensive agricultural and urban land use. Although much of the extant forest is increasingly protected by legislation, remnants continue to be degraded by the spread of non-native plant species, overgrazing, and recreational use. Some parks in the region have adopted management programs aimed at mitigating this degradation. Over the last 35 years, cottages and roads at Point Pelée National Park have been removed and sites either passively restored (i.e. road or cottage eliminated and vegetation allowed to regenerate) or actively restored (i.e. road or cottage eliminated, exotic vegetation removed, and native species planted). In 1994 and 1995, we assessed the effectiveness of restoration by comparing the understorey plant communities in 28 restored sites with those in less disturbed reference sites. There was a significant increase (P<0.0001) in the similarity of understorey plant communities between restored and reference sites as time-since-restoration increased. Soil moisture, canopy cover, distance to continuous forest, and site-shape all significantly affected plant species composition. Former road sites recovered significantly (P<0.05) more rapidly than former cottage sites, and the former lawns of passively restored cottage sites were the slowest to recover. Five years following active restoration, non-native ruderal species continued to dominate restored sites. The observed recovery of understorey plant communities in restored sites is attributed to their proximity to natural vegetation, and its function as a seed source. In some sites, recovery is substantial and, assuming present trajectories of change are maintained, we predict that recovery could occur in many mesic sites within the next 20 years. Restoration activity facilitates forest recovery and would appear to have a valuable function in mitigating ongoing conflicts between conservation and human use in this region.     

Phenotypic plasticity is maintained despite geographical isolation in an African cichlid fish,Pseudocrenilabrus multicolor

Gene flow among populations in different selective environments should favor the evolution of phenotypic plasticity over local adaptation. Plasticity in development is a common response to long‐term hypoxia in some widespread African fishes, including Pseudocrenilabrus multicolor, a cichlid that exploits both normoxic (high oxygen) rivers/lakes and hypoxic (low oxygen) swamps. Previous studies have shown that fish from normoxic and hypoxic sites differ in many traits, including gill size, brain size and body shape, and that much of this variation reflects developmental plasticity. However, these earlier studies focused on areas in Uganda where gene flow between swamp and river or lake populations is high. In this study we tested the hypothesis that P. multicolor from a relatively isolated lake population (Lake Saka, Uganda) exhibit low levels of plasticity in traits related to oxygen uptake. Multiple broods of P. multicolor from Lake Saka were reared under low and high dissolved oxygen, and traits related to gill size, brain mass and body shape were quantified. Surprisingly, both gill size and brain mass showed high levels of developmental plasticity. We suggest that high levels of plasticity, particularly in the gill size of P. multicolor, reflects low costs of maintaining the plastic response, even in relatively isolated populations.     

Soil Properties Required by Some Southern Africa Fruit Trees as Assessed by Discriminant Analysis

Some indigenous fruit trees, in the drylands of southern Africa are worthy of interest because of their adaptation to environmental conditions prohibitive for traditional crops. Their fruits or their derivatives are traditionally used as an additional income by rural population, but little information is available about the properties of the soils that support their growth, although this information is necessary if the trees are subjected to sustainable domestication. Several soil properties are, however, to be considered as a whole and discriminant analysis provides a helpful tool to individuate the best conditions for the tree growth. Thirty-five soil samples were taken in areas where the trees naturally grow and produce, and the analytical data of the surface layer were used to relate soil properties to tree species. Four groups of trees were well separated using two discriminant functions that takes into account both the fertility characteristics (pH, organic C, N, texture, and properties of the exchange complex) and the Fe contents and distribution among the oxide forms. The discriminant functions allow a very acceptable reclassification of the data (more than 80% of cases correctly reclassified) and the classification coefficients were used to build an empirical equation that may help to identify the most suitable tree to be introduced at a new site.     

新疆地方种亚麻农艺性状多元统计分析

为了新疆亚麻地方种的选育和改良提供理论依据,本研究采用对来自新疆各地的亚麻地方种性状的多元统计分析,包括变异系数、主成分分析、相关性分析和聚类分析。结果表明,新疆亚麻地方种资源存在较大差异,多样性比较丰富。主成分分析中,株高会影响构成亚麻产量的因子(蒴果数,果粒数,每株粒重和千粒重),亚麻的分枝数和株高都不能过多或过高,这不仅会影响工艺长度还会影响亚麻产量因子而且发现株高、生育期、分枝数、工艺长度、每株粒重、分枝数、千粒重和果粒数的相关程度较高。因此,在新疆亚麻地方种在选育时,可作为理论性数据参考,为亚麻品种选育和亲本的选择提供一定基础。     

新月弯孢菌及其近似菌菌落形态和可溶性蛋白电泳图谱比较分析

通过对分离自玉米及其他寄主的 12个新月弯孢菌菌株和 5个近似菌株菌落形态及可溶性蛋白电泳谱比较分析 ,表明菌落形态在不同种之间存在明显的差异 ,同种之间也存在一定差异 ,但不稳定和存在变异。 17个菌株可溶性蛋白SDS聚丙烯酰胺凝胶电泳显示 ,Curvularia属在Rf值为 0.177处有一条该属的特征蛋白带 ,新月弯孢菌在Rf值为0.225处有一条该种的特征蛋白带 ,但新月弯孢菌蛋白带存在多样性 ,聚类分析将未能确定的 13号菌株定为不等弯孢菌     

岭回归分析程序的设计与实现及农业应用实例

介绍了多元线性回归模型参数估计的最小二乘法和岭估计,分析了使用VisualBasic编程工具设计及实现岭回归分析程序的过程,阐述了岭回归分析程序的农业应用实例。     

多变量统计方法及其在作物环境胁迫研究中的应用

干旱、湿涝、高低温、盐渍等环境条件严重限制植物的生长发育和影响农作物产量.通过多变量统计分析,以主成分分析、因子分析、聚类分析、多重回归分析、隶属函数分析、灰色关联度分析、层次分析、多维空间坐标分析等方法为手段可筛选抗性强的品种,确定农作物抗逆鉴定的最佳时期及鉴定指标.目前多变量统计分析在农作物逆境抗性研究中得到广泛应用和发展,现已成为农作物抗逆鉴定的一个重要工具.     

A Critical Comparison of Typologies of Small-Scale Forestry in Baden-Württemberg Derived Using Single and Multiple Criteria

The paper presents a typology of small-scale forest owners in Baden-Württemberg based on multiple criteria and derived using multivariate cluster analysis of long-term accountancy network data. Four distinct types of landholders are identified based on a combination of structural, financial and biophysical data. These groups fit well with the present knowledge on small-scale forest owners in Baden-Württemberg. In addition, the members of each group display clear differences in attitudes towards forestry, giving further support for the validity of the grouping. A comparison is made of this typology and typologies derived using the single criteria of forestry region, forest size class, cutting volume, proportion of coniferous trees, forest income and main source of income. This comparison demonstrates the advantages of using cluster analysis to identify types of small-scale forest owners in south-west Germany. No matter whether structural, natural or financial data are assessed, the multiple criteria typology produced by cluster analysis provides the highest percentage of statistically significant distinctions between the medians of the groups identified. A typology based on the single criterion of ‘regions’ provides the second best fit and has the advantage of being simple to develop. A more detailed comparison between these two typologies, whereby the differences between groups were analysed based on the links between individual groups in respect to individual variables, also indicated that the multiple criteria typology was superior.