论峡江地区“烧龙”与“烧畬”的区别和联系

唐宋时期峡江地区“击鼓焚山”的民俗活动是远古时代尚巫之风的残存,其目的是为烧龙祈雨以禳除旱灾;而“烧畬下种”则是自远古“刀耕火种”传承下来的一门农耕技术,但由于“占卜伺雨”的仪式亦使它带上了一些巫风色彩。二者既有明显的区别又有一定的联系。     

OPTIMAL INVESTMENT IN THE PROTECTION OF A VULNERABLE BIOLOGICAL RESOURCE

It is assumed that the probability of destruction of a biological asset by natural hazards can be reduced through investment in protection. Specifically a model, in which the hazard rate depends on both the age of the asset and the accumulated invested protection capital, is assumed. The protection capital depreciates through time and its effectiveness in reducing the hazard rate is subject to diminishing returns. It is shown how the investment schedule to maximize the expected net present value of the asset can be determined using the methods of deterministic optimal control, with the survival probability regarded as a state variable. The optimal investment pattern involves “bang-bang-singular” control. A numerical scheme for determining jointly the optimal investment policy and the optimal harvest (or replacement) age is outlined and a numerical example involving forest fire protection is given.     

Design of an experimental procedure for energy evaluation from biomass

The rational and sustainable exploitation of nature resources is one of the priority objectives of our society. In this article a method is proposed to evaluate and exploit the energetic resources contained in different forest formations. This method is based on the use of a combustion bomb calorimeter to determine the calorific values of the different samples studied. These results were complemented with chemical analysis of the samples and with environmental and geomorphological studies of the zones were samples were taken. The results obtained during the last 3 years for the residual biomass originated from the forest formations existing in Galicia ensure the reliability and usefulness of the method that can be extended to any forest formation all over the world.     

Sparse graph certificates for mixed connectivity

We give a short proof for the Mixed Connectivity Certificate Theorem of Even, Itkis and Rajsbaum and provide an upper bound on the edge number of a certificate of local T-mixed connectivity up to k.     

太白山国家森林公园游客结构及行为特征研究

基于实地问卷调查资料,通过对太白山国家森林公园的游客结构及其行为特征分析,指出其主体客源为省内大中城市居民,游客年轻化的趋势较明显且以中低收入者为主,旅游活动是以基本层次的旅游观光居优;该旅游景区的自然风光使近80%游客的美感体验得到满足、且游客感应最深的是清新空气、山地气候及森林植被等,相对较差的是宗教文化;此外,四成多的游客对旅游服务质量不满意.针对上述结果,就太白山国家森林公园开拓客流市场、促销定位、促使其可持续旅游业发展提出理性建议.     

森林发展系统的一个非线性半离散模型

本文建立了森林发展系统的一类非线性林龄面积结构的半离散模型 ,并讨论了半离散系统解的存在唯一性 ,给出了线性半离散系统稳定的一些充分条件     

绿僵菌研究的新进展

简要介绍了国内外绿僵菌的研究概况，针对我国现阶段的研究进展情况，提出了今后工作的重点应放在加强高毒力菌株的选育、减少外界因素对绿僵菌防效的影响和减少菌株的抗药性等方面。     

山东栎林的基本特征(Ⅰ)

本文在调查了大量样方的基础上,分析了山东栎林的种类组成和地理成分,阐述了栎林的区系特征。     

太行山长城岭南山东北坡植被的研究

本文研究了太行山长城岭南山东北坡的植被分布及其特征。结果表明,从山麓至山顶,由于气候条件随海拨的逐渐升高而产生了明显的垂直变化,从而导致了植被分布的垂直变化。从山麓至山顶依次分布有落叶阔叶林、针阔混交林、针叶林和落叶阔叶灌丛等四个植被型、并因人为干扰落叶阔叶林正向针阔叶混交林和针叶林方向演替。     

Stable Solution of Nonlinear Age-structured Forest Evolution System

This paper studies the dynamical behavior of a class of total area dependent nonlinear age-structured forest evolution model. We give the problem of equal value for the forest system, and discuss the stable solution of system. We obtained the necessary and sufficient conditions for there exists the stable solution.