混交林与纯林的生态经济优势机理分析

Analysis of Ecological Economic Advantages of Mixed Forest and Pure Forest

基于混交林的相关研究成果,对混交林与纯林的生态与经济优势进行比较分析的结果表明:⑴混交林因具有垂直成层结构及树冠可塑性,从而能更有效利用林冠空间;⑵混交林枯枝落叶层因各种枯枝落叶混交,进而加快无机养分的循环;⑶某些特定混交树种由于具有固氮作用以及不同的根系分布模式、生长节律及资源利用方式,从而能够获取更多生长所需的资源;⑷混交林具有更强的抗霜害及病虫害能力;⑸在一定条件下,某些林地上的混交林表现出经济效益的优势;⑹混交林不仅能产生可观的经济收入,而且还具有降低金融风险的优势;⑺除木材经济效益外,混交林还具有诸多边际效益等;⑻混交林具有长期经济收益优势,而且在维护林地长期生产力、高水平的生态服务和功能方面明显优于纯林。总体来说,与纯林相比,混交林具有明显的生态与经济优势,能提供更为多元化、优质的生态服务。

⑴Background--Pure forests,which are easy to intensive management and have high economic value,have been highly praised by forest managers since the beginning.In the 20th century,due to the single species,simple structure and weak disaster resistance of the planted pure forests in European forestry developed countries,large-scale and severely damaged pests and snowstorms frequently occurred,causing the significant loss of forest economy.Then mixed forests began to gradually catch the attention of the operator.With the occurrence of environmental problems,the development of mixed forests in China is gradually attracting the attention of government departments and forestry science and technology workers.⑵Methods--At present,researches on mixed forests and pure forests in China mainly focus on the mixed forest construction mode,growth and development status,community structure and succession,soil physical and chemical properties and so on.However,there are relatively few analyses on the ecological and economic advantage mechanism of mixed forest and pure forest.Therefore,this paper mainly summarizes and analyzes the advantage mechanism of the ecological and economic advantages of mixed forests in order to provide theoretical reference for the development of mixed forests in China.⑶Results--The result shows that compared with pure forest,①mixed forest could utilize canopy space more effectively and improve forest productivity and nutrient cycle because of its vertical stratification structure,canopy plasticity and niche separation,etc.②The litter layer of mixed forest is mixed with all kinds of dead branches and leaves,which can accelerate the circulation of inorganic nutrients.This is mainly due to the decomposition of litter in mixed forest,which is influenced by litter humidity,temperature and PH value,litter mass,litter decomposer and interaction between different litters,and so on.As a whole,the decomposition of mixed litter is greater than that of single litter.③Due to the different resource utilization modes,root distribution patterns and growth rhythm,some specific mixed tree species have more extensive use of canopy space,which enables them to obtain more resources needed for growth.For example,some specific mixed tree species can obtain more resources for growth because of their nitrogen fixation,different root distribution patterns,growth rhythms and resource utilization patterns.④Mixed forests have stronger ability to resist frost and pests;however,pure forests are easy to cause natural disasters such as snowstorm,drought,diseases and insect pests,resulting in the loss of biological diversity and serious damage to the ecological environment due to single forest stand.⑤Under certain conditions,the mixed forests on some woodland show the advantage of economic benefit.⑥Mixed forests not only generate considerable economic income,but also have the advantage of reducing financial risk.When the market needs change,pure forest lacks flexibility,while mixed forest has the cutting option and can carry out reasonable cutting according to the change of timber market situation,so as to maximize the economic and ecological benefits.⑦In addition to timber economic benefits,mixed forests also have many marginal benefits.Generally speaking,mixed forests not only have high aesthetic value and tourism value,but also provide different habitats and food for a variety of wildlife,while pure forests can only provide such conditions for a small number of wildlife.⑧Mixed forests have the advantage of long-term economic benefit,and are better than pure forests in maintaining long-term productivity and high levels of ecological services and functions.⑷Conclusions and Discussions--In general,compared with pure forest,mixed forest has obvious ecological and economic advantages and can provide more diversified and high-quality ecological services.Especially in the context of climate change,mixed forests can solve future development uncertainties and environmental problems.