Impact of introduced honey bees on native pollination interactions of the endemic Echium wildpretii (Boraginaceae) on Tenerife, Canary Islands

The aim of this study was to investigate effects of introduced honey bees (Apis mellifera) on native pollination interactions of Echium wildpretii ssp. wildpretii in the sub-alpine desert of Tenerife. We selected two study populations, one dominated by honey bees, while the other was visited by many native insects. During peak activity period of insects, nectar was nearly completely depleted in flowers of the first, but not the latter population. Thus, a high abundance of honey bees may have suppressed visitation by native animals due to exploitative competition. Honey bees stayed longer and visited more flowers on the same inflorescence than native bees, thus potentially promoting self-pollination of the plants. Level of seed set and viability was similar in the two study populations. However, we cannot rule out long-term changes in genetic population structure due to changes in gene-flow patterns caused by foraging behaviour of honey bees vs. native flower-visitors.     

一种新的竞争指标——树冠影响度

可变竞争区域类竞争指标根据对象木某个描述型指标函数确定竞争区域;而树冠在树木的生长过程中具有重要的作用,并且反映了树木的长期竞争水平,根据这两种思想提出一种新的竞争可变区域类竞争指标——树冠影响度。采用典型选样法设置研究样地,并对样地内树种的各个测树因子进行调查统计,应用树冠影响度对数据进行分析讨论,结果显示:样地树种平均树冠影响度为0.359 4,样地中群落竞争相对较弱,群落结构相对稳定,其中马尾松(Pinus massoniana)的树冠影响度最小,为0.261 3;枫香(Liquidambar formosana)的树冠影响度最大,为0.510 1。优势种群树种平均树冠影响度小于非优势种群树种,优势种群受到的竞争较小,竞争能力较强,针叶树种平均树冠影响度小于阔叶树种树种,针叶树在群落中处于优势地位。     

The effects of belowground resources on aboveground allometric growth in Bornean tree species

Tree height and crown allometries reflect adaptations for resource acquisition and structural stability, as well as plastic responses to a heterogeneous environment. While both light and soil resources limit growth and influence competitive responses in tropical forests, the effects of belowground resources on allometries are less understood, especially within the understory. To characterize outcomes of tree competition along an edaphic resource gradient, we quantified variation in height and crown allometries of six Bornean tree species from contrasting regeneration niches (light-demanding vs. shade-tolerant) on two soil habitats (clay-fine loam and sandy loam) within a 52-ha forest dynamics plot. Using empirically-fit allometric parameters and diameter growth rates from plot census data, we modeled tree height and crown area growth over the projected life span of each species. Based on resource competition theory, we hypothesized that tree species specializing on and populations of generalist species growing on the relatively moister, more fertile clay-fine loam soil habitat would have faster height and crown growth rates, compared to those on the sandy loam habitat, regardless of regeneration niche. Among soil specialists and within generalists of both genera, trees growing on clay-fine loam had taller stems and larger crowns at a given age and faster height and crown area growth rates at most sizes than trees on sandy loam. Differences in height and crown growth were driven by the faster diameter growth rates of trees on clay-fine loam, not by differences in height- and crown-diameter allometries, as trees on sandy loam were significantly taller at a given diameter, and differences in crown allometry were not consistent across soil habitats. Characterizing the height and crown growth responses of trees along resource gradients provides insight into the mechanisms that maintain diversity in tropical forests. Our results point to the importance of adaptive and plastic responses to both above and belowground resource availability in determining the allometric growth of trees and suggest that this diversity of responses may contribute tree species coexistence through competition-based trade-off mechanisms and variation in growth among individuals. Additionally, as the importance estimating natural carbon sequestration increases with the escalating effects of anthropogenic climate change, differences in tree growth and architecture across soil habitats also have implications for the approximation of forest carbon storage on heterogeneous tropical soils.     

中亚热带檫树群落种问竞争及其种群密度调节的研究

研究中亚热带檫树群落种间竞争关系结果表明 ,平衡时檫树与其主要伴生树种光皮桦、丝栗栲重要值分别占 80 .6 4 %、12 .4 7%和 6 .89% ,呈共优状态但分布极不均匀。利用自疏模型并经改进单纯形法最优拟合求得檫树种群密度效应模型 ,且拟合结果达显著水平 ,反映出檫树种群自疏过程密度调节规律。     

基于种间竞争的遗传算法的改进

提出基于种间竞争的基本遗传算法的改进算法,并编写程序实现该改进算法.通过考核实例计算,发现改进后的算法具有更强的鲁棒性.     

柳杉人工林单木材积生长模型的研究

本文将柳杉人工林单株木的林积生长量作为年龄、地位指数、竞争指数的函数，建立单木生长模型。研究结果表明：简单竞争指数优于竞争压力指数，而在简单竞争指数中，竞争木取６株和８株差别不大，均优于竞争木取４株。进一步的分析表明：在不受人为干扰的林分中，竞争木取６株和８株的简单竞争指数在一定时期内保持相对稳定的状态，与林分年龄和立地质量关系不密切，而与胸径之间存在着密切的相关关系。其值随着胸径的增大而减小，二者之间的关系用双曲线和幂函数拟合较为适宜，由此建立的简单竞争指数预估模型，扩大了单木生长模型的运用范围。在理论上和实践上均有重要的意义。     

寄主龄期、温度对菜蛾盘绒茧蜂与菜蛾啮小蜂种间竞争的影响

在室内调查了分别以2龄、3龄和4龄小菜蛾幼虫作寄主时,及20、26、28和32 ℃下菜蛾盘绒茧蜂和菜蛾啮小蜂间竞争结果.当2龄或3龄小菜蛾幼虫供2种蜂同时产卵寄生时,绒茧蜂的寄生率显著高于啮小蜂的寄生率;分别与其单独寄生时比,前者无显著差异,而后者则显著下降;二种蜂的合计寄生率与任一种蜂单独存在时的相比,以2龄幼虫作寄主时无显著差异,但以3龄幼虫作寄主时则显著提高.当4龄小菜蛾幼虫供2种蜂同时产卵寄生时,绒茧蜂的寄生率与啮小蜂的寄生率之间无显著差异;二种蜂的合计寄生率显著比绒茧蜂单独存在时的高,但与啮小蜂单独存在时的寄生率相比无显著差异.当2种蜂共存时,在所测试的4个温度下,绒茧蜂的寄生率均高于啮小蜂的寄生率,与其单独寄生时的相比,绒茧蜂的寄生率无显著变化,而啮小蜂的寄生率均显著下降.这些结果表明寄主龄期比温度对这两种蜂种间竞争的影响更大.     

乳源木莲混交林种内及种间竞争研究

利用单木竞争指数模型 ,研究富口和黄坑乳源木莲种内和种间的竞争强度的大小 ,结果表明 :间伐时间的不同 ,对乳源木莲种内与种间竞争强度影响很大 ,富口和黄坑种间竞争均大于种内竞争 ,但黄坑的乳源木莲种内和种间的竞争强度均大于富口 .竞争指数与对象木胸径符合幂函数关系 ,并达到显著水平 ,乳源木莲种内、种间及整个林分的竞争强度随着对象木胸径的增大而下降 ,并维持在较低的水平     

基于SWOT分析构建天目山国家级自然保护区管理策略

通过对浙江省天目山国家级自然保护区管理局、临安市西天目乡人民政府和周边社区不同类型村民代表等主要相关利益者的12个小组访谈,及104个农户和59个社会公众的问卷调查,以SWOT为分析框架,阐述天目山国家级自然保护的强势与机会及弱势与挑战。强势与机会有:①国家可持续发展战略的实施;②当地生态旅游的发展;③基于非木质资源利用为主的产业结构;④当地居民良好的环境保护意识;⑤社区共管模式雏形的出现;⑥强有力的林业科研力量支撑。弱势与挑战为:①对当地社区居民的利益补偿机制不完善;②自然保护与社区利益共享机制未完全形成;③社区共管机制尚不健全;④自然保护区总体规划滞后;⑤自然资源和生态环境出现退化。提出了构建自然保护区与周边社区利益共享和伙伴合作机制的设想。表4参8     

森林火灾扑救智能决策模型研究

该文介绍了一种森林火灾扑救智能决策支持系统的结构,提出了资源竞争决策的思想,并建立了决策模型.其中,典型模型有防火道构筑决策模型、距离计算模型和决策结果评价模型.运用该模型,输入仿真条件,即可得到相应的决策方案,为扑火指挥员做出更合理的决策提供重要依据.