基于GEP核算的北京市山区森林经营实施效果评价

以北京市为研究区构建GEP核算体系,通过市场价值法、替代成本法等价值评估方法核算2000、2010年和2018年生态系统生产总值,分析探讨北京市生态系统服务价值的动态变化特征,明确森林经营技术优化对生态系统服务功能的提升效果,为优化森林生态系统经营技术提供重要科学依据。结果表明:(1)2018年,北京市GEP三大服务中,调解服务价值量最大,文化服务价值量次之,供给服务价值量最小。(2)2000、2010、2018年的GEP分别为2572.45、3961.02、5603.04亿元,GEP和GDP呈现双增长态势,对应的绿金指数(GEP/GDP)分别为0.80、0.27、0.18,呈逐年下降的趋势。(3)按可比价计算,2000-2018年GEP增幅40.53%,其中2000-2010、2010-2018年增幅分别为18.89%、18.20%,GEP增幅有所减缓,但森林经营提升生态效果总体呈现向好趋势;供给服务价值幅度为40.46%,调解服务价值增幅为10.63%,文化服务价值增幅525.91%。研究利用GEP核算结果反映山区森林经营技术优化效果,进一步推动北京市山区森林生态文明建设。

马尾松人工纯林近自然化改造效果分析

[目的]以马尾松人工纯林为对象,分析其近自然化改造后森林质量变化和树种发育情况,为此类人工纯林的近自然化经营提供参考和决策依据。[方法 ]2007年在广西凭祥中国林科院热带林业实验中心对马尾松纯林开展近自然改造试验并设置样地20块,其中经营样地16块、对照样地4块;于2007年第一次全面调查获得本底数据之后,冬季执行目标树抚育择伐;2008年春执行6个阔叶树种4种组合的林下补植作业;2016年实施第二次目标树抚育伐;2007年后,每2年执行1次样地复测调查,共获取了7期数据。对7期监测数据的重要值指数、平均胸径和纯生长量等指标进行统计,从树种组成、林分结构、林分生长等方面对马尾松人工林近自然化改造效果进行分析和评价。[结果 ]近自然化改造的马尾松人工纯林经过13 a后,林分逐步过渡到异龄复层混交林结构。林下补植的6个树种的重要值均处于前10名,林分中出现了安息香、油桐等树种的天然更新。近自然化改造的马尾松林的林木从5 cm起测径阶到55 cm径阶范围内均有分布,呈现出经营措施促进下快速形成混交异龄林格局的发展动态;而未作处理的对照林分依然呈同龄纯林的径级分布。就生长而言,近自然化改造林分生长量显著高于对照林分,并且林分生长量主要集中于较大径阶林木,实现了林分价值的显著提升。[结论 ]人工纯林近自然化改造中,调整树种组成是最关键的经营措施;扩大径级结构分布范围是针叶纯林近自然化改造的基本指标;近自然化改造显著提高了森林的生长量和蓄积量;同时促进了土壤微生物发育,改善了森林土壤和生态系统整体质量。

基于森林功能分区的经营小班划分研究

基于湖南省慈利县二类调查数据,根据森林主导功能的差异、森林林种种类和坡度的不同,将慈利县森林划分成不同的森林功能区,并基于森林功能区按照树种的不同将其进一步划分成不同的经营小班。最后,在地理信息系统的支持下绘制出森林功能分区图和经营小班划分图。结果表明,公益林的面积多于商品林的面积,其中特殊公益林区和一般公益林区面积为1290 hm^2,限制性商品林和一般性商品林面积为1144 hm^2,马尾松和杉木是主要的经济树种。划分经营小班有利于森林的分类经营,为实现林业从传统的以木材生产为主向发挥森林的多功能、多效益的经营方式转变提供条件,进而实现森林的可持续经营,并为促进森林经营单位的可持续发展提供数据支持。

Distribution Patterns and Associations of Dominant Tree Species in a Mixed Coniferous-Broadleaf Forest in the Changbai Mountains

In 2012 a plot was established with 1-ha area in a mixed coniferous-broadleaf forest in the Changbai Mountains, northeastern China for examining local forest processes, structure and succession. A method of O-ring statistics(paircorrelation function) was applied to analyze the spatial patterns and associations of the dominant species within different vertical layers. After the evaluation by their importance values, six tree species(or group)(i.e. Abies nephrolepis, Picea jezoensis, Pinus koraiensis, Tilia amurensis, and species group of Betula ssp. and species group of Acer ssp.) were determined as dominant trees species. It was found that some of these species exhibited closely clustered distributions at fine distances. As spatial distance increased, a random or even regular distribution gradually appeared with the exception of the upper layers of A. nephrolepis and P. koraiensis, and the lower layers of P. jezoensis, P. koraiensis and Betula ssp., which were substantially randomly distributed. Intra- and inter-species spatial associations varied in accordance with species, tree height and reciprocal distances. Positive associations were observedbetween the lower and upper height classes of trees of the same species(except for that of P. jezoensis) at fine distances. This may be owing to limited seed dispersal and geological heterogeneity. The aggregation intensity declines with increasing distances and this consistent with the predictions of self-thinning. Some coniferous trees(e.g. Pinus koraiensis) in the lower height class were positively associated with T. amurensis and group of Betula ssp. of the upper height class at some distances, suggesting that saplings of coniferous trees occupy a broader niche and can grow well under the canopy of the adult of broad-leaved trees. Negative associations were observed between upper coniferous trees and lower broad-leaved trees and between upper P. jezoensis and lower P. koraiensis, suggesting that a canopy of these trees might not provide suitable environment for the survival, establishment, and growth of lower individuals, corresponding well to Janzen-Connell hypothesis.

Structure and regeneration dynamics of three forest types at different succession stages of spruce – fir mixed forest in Changbai Mountain, northeastern China

Analyzing and understanding the structure and growth dynamics of forests at different stages is helpful to promote forest succession, restoration and management. Three spots representing three succession stages of spruce-fir mixed forest(SF: polar-birch secondary forest, MF: spruce-fir mixed forest and PF: spruce-fir near primary forest) were established. Structure, growth dynamics during two growth seasons for dominant tree species, regeneration were examined, and a univariate O-ring function statistic was used to analyze the spatial patterns of main regeneration tree species. Results showed that,(1) composition of tree species, periodic annual increment(PAI) of the diameter at breast height(DBH), basal area for overstory trees and of ground diameter(DGH) for saplings, were significantly different with the succession;(2) the current species composition and regeneration dynamics of SF suggested a development towards spruce-fir mixed forests. Pioneer species like Betula platyphyllaa will gradually disappear while climax species, such as Abies nephrolepis, Pinus koraiensis, Picea koraiensis and Tilia amurensis will dominate forest stands;(3) Despite the highest volume occurring in PF, and saplings in it grew better than in the others, this forest type is unstable because of its unsustainable structure of DBH class and insufficient regeneration; and(4) MF had the most reasonable distribution of DBH class for adult trees(DBH > 5.0 cm) and DGH class for saplings(H ≥30 cm and DBH ≤5 cm), as well as an optimal volume increment. Limiting canopy opening size can lessen the physiological stress and promote the growth and competitive status of regeneration. Management implications for increasing the gaps and thus creating better growth conditions for understory saplings and facilitating forest succession were discussed.

Plantation transformation alternatives determine carbon sequestration capacity – a case study with Pinus massoniana in southern China

It is widely accepted that global warming, which results from the increase of carbon dioxide(CO2) in the atmosphere, has a negative impact on human beings. Forests are the largest terrestrial ecosystem and play an important role in carbon sequestration. Many studies have documented that a mixed-species forest can sequester more carbon than single species forests, depending on the site conditions. Therefore, uneven-aged mixed-species forest management has been receiving more and more attention. In 2008, an experiment with five silvicultural models for Pinus massoniana(Chinese red pine) plantation, i.e., four transformation treatments(A1-A4) and one control treatment(A5) was conducted in the Experimental Center of Tropical Forestry of Chinese Academy of Forestry in Pingxiang City, in southwestern Guangxi Zhuang Autonomous Region, southern China. The four transformation treatments(A1-A4) enriched Castanopsis hystrix, Manglietia glance, Erythrophleum fordii and Quercus griffithii with differed richness and composition after thinning(removed 70% of trees), while no silvicultural treatment was used in the control treatment A5. In this study, we compared the carbon sequestration capacity of these five silvicultural models based on periodic annual increment and growth rate. Our results indicated that all the transformation treatments performed significantly better in carbon sequestration than the control treatment. A significant difference was also observed amongst the transformation treatments. Moreover, the transformation treatment A1 with enrichment species Castanopsis hystrix(350 trees·ha^-1) and Manglietia glance(350 trees·ha^-1) was determined to be the optimal model for maximum carbon sequestration because of its high tree-level growth rate and high economic value of enriched plantings, which could be popularized in other places. Our results further confirmed that management using mixed-species forests is a better approach to combat climate change than using monoculture forests.

Identifying indigenous tree species for land reforestation,forest restoration, and plantation transformation on Hainan Island, China

Selecting suitable species is the most important issue for bare land reforestation, degraded secondary forest restoration, and single-species plantation transformation. However, little information has been documented related to tree species selection for these silvicultural endeavors on tropical Hainan Island of Southern China. The present study employed Baisha County, the ecological core area of Hainan Island, as a case study area. We initially inventoried a slightly disturbed primary forest and attempted to produce diameter distribution curves for each tree species. Second, the tree species were classified into shade intolerant, opportunist, and shade tolerant species based on shape of their diameter distribution curves. Third, market value was determined for each tree species based on published literature and on-site investigations at local wood trading companies. Totally 118 tree species were encountered in the inventoried forest and 13 tree species present were finally identified as potential tree species for our silvicultural endeavor on Hainan Island, of which 3 species are shade intolerant, 5 species are opportunist and 5 species are shade tolerant. Additionally, we also selected 12 tree species that were not in the inventoried forest but were extremely economically valuable and ecologically important. This study should contribute to the formulation of a sustainable forest management strategy on Hainan Island and the methodology might be replicated in other tropical region where suitable species also need to be identified for silvicultural endeavor.