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1.
An understanding of forest carbon budgets, such as the factors that influence different levels of carbon accumulation, is one of the first steps in protecting and restoring areas of plant cover. Univariate and multivariate regression analysis was applied to evaluate the influence of climate variables (Rainfall, and mean maximum and minimum temperatures) on intra-annual above-ground carbon accumulated in tree species of the Caatinga. Above-ground carbon accumulated in the trees was 0.06 Mg ha?1 month?1. Carbon allocation in the aerial parts of the trees increased significantly with rainfall. Maximum and minimum temperature had little influence on carbon storage; however, variations in carbon accumulation are best explained when minimum and maximum temperatures are added to the regression model for rainfall, thereby demonstrating the simultaneous effect of these variables, and better explaining the carbon increase.  相似文献   

2.
Siberian moth Dendcrolimus superans sibiricus Tschetw. is the main important insect pest not only in Siberian coniferous taiga, but it often forms foci of mass reproduction in larch stands in the Russian Far East. This article has described outbreaks of the Siberian moth and other insect pests since 1960 till now.  相似文献   

3.
概述了近20年来国内外对催化α-蒎烯氧化反应过程的研究,重点分析了α-蒎烯氧化中催化剂的性能特点及产物分布规律,总结了过渡金属盐、氧化物、配合物、分子筛及杂多酸在α-蒎烯氧化中的催化作用,比较了催化活性及选择性的特点,并初步探讨了发展趋势.提出在已有的α-蒎烯氧化反应催化剂中,分子筛类催化剂在制备方法和工业化发展上有一定的优势,深入研究过渡金属化合物在α-蒎烯氧化反应的催化性能及调变方法,应是α-蒎烯氧化反应中值得重点关注的研究内容.  相似文献   

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5.
利用生态脆弱度的灰色评判法建立了沙质荒漠化的干扰-应变关系,进而求算了不同荒漠化程度样地的生态脆弱度,结合气候、地貌、植被、土壤等特征指标对东北西部沙质荒漠化地区土地荒漠化作出评价:该区的土地沙质荒漠化可分为强度沙漠化、中度沙漠化、轻度沙漠化、微度沙漠化、潜在沙漠化五个级别,各等级及其相应的生态脆弱性、植被群落多样性、群落稳定性等指标可用于中小尺度的荒漠化土地评价图的绘制,其可作为土地荒漠化防治的重要理论依据.  相似文献   

6.
Forest structure and function strongly depend on and concurrently influence environmental conditions.Tree performance is generally governed by its genetics and environment;thus,recent hotspots in this field include tree genotype × environment,phenotype × environment,and functional trait × environment interactions.The editorial,review,and 22 original research articles in this Special Issue, "Tree ecophysiology in the context of climate change",highlight ecophysiological phenomena(e.g.,climate hor...  相似文献   

7.
Seasonal variation of paulownia witches’-broom (PWB) phytoplasma within different organs (leaves, branch and trunk bark and roots) in paulownia trees was investigated by the amplification of a PWB-specific DNA fragment by the polymerase chain reaction (PCR). In leaf samples, PWB phytoplasma was first detected in June and the incidence gradually increased. On the other hand, the PWB was detected at relatively low incidence in branch bark, trunk bark and roots and the incidence did not change among seasons. A survey of PWB in 27 fields in the Tohoku district of Japan showed that malformed flower buds were observed in paulownia trees in almost all of the fields. PWB-phytoplasma was also detected by PCR from paulownia trees in almost all of the fields in Iwate and Fukushima Prefectures. The frequencies of trees in which phytoplasma was detected by PCR were higher than those in which symptoms were observed. These results indicated that PCR amplification of a PWB-specific DNA fragment is an effective tool for practical diagnose and that PWB is widely distributed in the Tohoku district of Japan.  相似文献   

8.
Models constructed from machine learning are a potential non-parametric alternative for the prediction of biometric variables in opposition to traditional regression modeling. The hypothesis of this study was that the non-parametric approach with the k-Nearest-Neighbor algorithm (k-NN) has the possibility of presenting better accuracy with lower demand for predictor variables in the estimates of T. grandis trunk volume than the traditional volumetric models applied in forest sciences. Ten volumetric models were adjusted. In the regression k-NN was defined as maximum of 25 (25-NN), but with learning only for the odd neighbors starting at 3-NN. The optimal k nearest neighbor for two variations of predictors was obtained through repeated cross-validations. Spurr (ln) and Schumacher-Hall were the most accurate linear models that meet the linear regression assumptions. The optimal k nearest neighbor for the algorithm was k = 5 for the two variations of predictors. The use of the k-NN estimator may be a more general approach to linear regression especially when the assumptions made about the errors are not satisfied. However, its use should be considered only when traditional linear regression models or other simpler methods do not show good results.  相似文献   

9.
1 INTRODUCTIONUrban Forestry is an emerging science and art in thePhilippines. Its concepts and principles are quite similarwith traditional forestry being both resourcemanagement systems. However, urban forestrysobjectives are more focused on the protective,ameliorative, aesthetic and amenities rather than onproductive roles.As a resource management strategy, urban forestryinvolves wise use, management and/or manipulationof the resources that include individual trees and otherplants com…  相似文献   

10.
EffectsofForestontheBudgetsofWater,EnergyandGasesintheEnvironmentHeQingtang,SongCongheCollegeofForestResourcesandEnvironment,...  相似文献   

11.
Forests expanded rapidly in northwestern Vietnam in the 1990s. Forest expansion coincided with a new forest policy that mandated the devolution of forest management authority. A cornerstone of the new policy was the allocation of use rights for forestry land and trees to rural households. This paper examines to what extent the new forest policy contributed to the observed forest expansion. The findings of three village studies suggest that the new forest policy had minor effects on actual property rights, as villagers resisted its implementation. Instead, forests expanded, mainly due to the liberalization of agricultural output markets and availability of new technology. Changes in markets and technology motivated farmers to intensify crop production, reducing agricultural pressure on land. The research findings suggest the potential of market-based instruments and technology policy to facilitate forest regeneration. They also demonstrate the benefits of in-depth village studies for forest policy analysis, as it provides an integrated framework for assessing the relative effects of political, economic and technological changes on forests.  相似文献   

12.
本文报道了毛白杨三倍体育种的研究进展.应用染色体加倍、种间杂交和花粉辐射技术,成功选育出了20个回交杂种异源三倍体无性系,最优三倍体无性系8年生单株材积达到了0.36m3,超过一般二倍体的2.55倍.由此表明,育种材料的遗传组成和育种方法是获得较高遗传增益的基础.二倍体选种增益一般为45%,回交杂种增益为155%,而异源三倍体最优无性系的增益为255%.  相似文献   

13.
Woody plants contribute to the stability and productivity of terrestrial ecosystems and are significantly affected by climate change.According to the concept of environmental hormesis,any environmental stressors can cause hormesis,that is,stimulation in low doses and inhibition in high doses.Numerous studies have demonstrated plant hormesis under low doses of various abiotic stressors.However,the hormetic responses of woody plants to abiotic stressors from climate change are insufficiently studi...  相似文献   

14.
1 INTRODUCTIONThe Loess Plateau is the most drastic soil erosion regionin China, with the most severe water erosion. Thedistribution of types and intensity of erosion not onlyhave regional diversity but also have perpendicularvariation. In the small watershed, there are differencesin erosion characters among its upper, middle and lowerreaches. It is very significant for taking rationalmeasures of soil and water conservation and forpreventing soil and water loss to analyze the relationbe…  相似文献   

15.
We investigated the correlation of large fires([300 ha) from 1992 to 2013 within the borders of the Antalya Regional Directorate of Forestry using the Keetch–Byram drought index(KBDI). Daily KBDI values were calculated for each year, and values for the period before the year 2000 differed significantly from those after2000. After 2000(large fires occurred in 2004, 2006, 2007,2008, 2010, and 2013), when KBDI values increased, the KBDI, but not the number of fires, was inversely correlated with the natural log of the burned area(NLBA). While there were both high and low KBDI values when the NLBA was small, only high KBDI values were associated with high NLBA values. Particularly for logarithmic values of 4 and higher, KBDI values increased in parallel with increases in NLBA values. On the basis of a Mann–Whitney U test done in addition to a Pearson correlation test, we found that when the burned areas were grouped according to small and large areas, the KBDI could be used to distinguish the two groups. Using a conditional probability analysis, we found that 4th, 5th and 6th class KBDI values may lead to large fires at the 60 % possibility.Similarly, the possibility of large fires greater than the median burned area in any given 6 years was found to be48 %. In addition, while the mean value of KBDI is 390.51 for the period from May to September for these 6 years, it is 359.93 for the other years. Consequently, the area burned also increased as the KBDI classes(Class 0: 0–99, Class 1:100–199, Class 2: 200–299, Class 3: 300–399, Class 4:400–499, Class 5: 500–599, Class 6: 600–699, and Class 7:700–800) increase.  相似文献   

16.
IntroductionAsagrowthmodelforanindividualtreeorforeststhnd,theChapman-RichardsFunction,anextensiontotheVonBertalanffy'sgrowththeory(Bertalanffy1957)embodiesallotherestablishedgrowthfunction.ThisfunctionhasbeenwideIyusedinforestrybecauseofitsflexibility,ac…  相似文献   

17.
AttendingtotheNeedsofLocalPeopleinNatureReserves-AnImportantMeasureintheEstablishmentandProtectionofNatureReservesTXAttendingt...  相似文献   

18.
本文研究了长江三峡花岗岩地区林地土壤流失特性.结果表明由鳞片状面蚀导致的土壤流失量月分布与月降雨量的分布趋势基本一致,二者呈现出较为明显的线性相关关系.植物盖度≥0.70的林地土壤流失多集中发生在6~9月份,土壤流失量在5000t·km-2·a-1以下.盖度<0.7的林地土壤流失年内分布时间多在3~10月份,土壤流失量为500~6000t·km-2·a-1.  相似文献   

19.
Ownership is a multidimensional phenomenon that includes legal, social, and emotional aspects. In addition to legal aspects, the social and emotional aspects, “feelings of ownership,” potentially have behavioral effects. Nevertheless, these aspects are often overlooked in the research influencing the forest owners' behavior and thus their forest management decisions. This article examines how private forest owners with inherited forest holdings construct feelings of ownership toward their forests and how these constructions are reflected in their forest management decisions. Forest ownership is addressed through the theory of psychological ownership. On the basis of 15 thematic in-depth interviews, we suggest that a sense of identity and control, as dimensions of psychological ownership, can influence whether forest management decisions are guided by tradition, economic incentives, or responsibility toward property. Based on the results, a forest owner typology (restricted, indifferent, informed, and detached forest owners) was constructed, further enabling us to understand the differences among private forest owners and the roots of their forest management decisions. More generally, the study highlights the important role of emotions in forest management decisions.  相似文献   

20.
This article addresses the German debate on the issue of the common welfare designation of public forests. In the first part, drawing on two case studies, the political discourse on the issue is introduced. Two major competing ‘story lines’ can be made out that are both based on a long tradition of controversially discussed concepts of regulatory forest policy. While they both emphasise that common welfare services in forestry run counter to profit orientation, they fundamentally differ with regard to the consequences for forest policy, e.g., considering the degree of state intervention. Afterwards, an overview on the scientific debate on common welfare in the German context is given, and different concepts of common welfare determination are distinguished. Existing approaches of common welfare determination in German forest policy are related to these concepts and discussed. It is argued that the common welfare designation of the public forest is only insufficiently implemented by the actual governance arrangements. Based on this consideration, eventually, the implementation of a procedural concept of common welfare operationalisation in Germany’s public forests at the local level is proposed. While such a concept will not solve all complex problems related to the determination of common welfare in public forestry, it would notably contribute to a more operational definition of common welfare in public forestry and a more informed public debate on the issue.  相似文献   

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