基于π值法的兴安落叶松天然混交林林分状态研究

Stand Status of Natural Mixed Forest of Larix gemlinii Based onπValue Method

【目的】森林是一个复杂的生态系统,林分状态的合理与否直接关系到森林经营的必要性与迫切性。明确最优林分状态,构造最优评价指标体系,对于合理评价东北林区不同林型森林质量以及制定合理的森林经营方案具有重要意义。【方法】根据大兴安岭南翁河地区的兴安落叶松白桦混交林和兴安落叶松柞树混交林的标准地调查数据,分别计算林分空间结构、林分年龄结构、林分组成、林分密度、林分长势、顶级树种竞争、林分更新和林木健康等8个方面的林分状态指标,并对其进行归一化处理。利用现实林分状态计算公式计算两种不同兴安落叶松混交林的现实林分状态值,并确定林分状态等级。此外,还分析了两种混交林中落叶松的生长状态。【结果】兴安落叶松白桦混交林和兴安落叶松柞树混交林均具有良好的空间结构和年龄结构,表现为林分状态指标赋值均为1,达到了最优林分状态标准。然而由于未经过抚育间伐,导致林分密度拥挤、林分更新不良、健康林木比例低下,表现为林分密度、林分更新和林木健康等指标的赋值为0,严重影响了现实林分状态等级。林分组成、林分长势和顶级树种竞争等指标均在0.5左右,其中林分组成指标数值低于0.5,说明这两种林型树种均比较单一;林分长势和顶级树种竞争指标数值高于0.5,说明林分长势良好,目的树种占主要优势。通过计算两种林型的ω值发现,两种林型均处于较差的现实林分状态,所以,制定合理的森林经营方案,通过抚育间伐等措施调整林分密度,改善林分更新情况,提高健康林木比例,将对提高林分整体质量等级提供帮助。兴安落叶松在与不同树种混交时具有不同的生长状态,所以,有针对性的林分调整对于提高森林质量同样重要。【结论】本研究可为大兴安岭地区兴安落叶松白桦混交林和兴安落叶松柞树混交林的森林经营决策提供理论依据。

【Objective】The forest is a complex ecosystem,and the rationality of the stand status is directly related to the necessity and urgency of forest management.Defining the optimal stand status and constructing the optimal evaluation index system is great significance for the reasonable evaluation of the forest quality of different forest types in the northeast forest area and the formulation of a reasonable forest management plan.【Method】This study based on the standard survey data of the mixed forest of larch(Larix gmelinii)and birch(Betula platyphylla)and the mixed forest of larch(Larix gmelinii)and Mongolian oak(Quercus mongolica)in the Nanwenghe area of Daxing’an Mountains.The stand status indicators of forest stand spatial structure,stand age structure,stand composition,stand density,stand growth,top tree species competition,stand renewal and forest health were calculated and normalized.Processing.The actual stand status of two different mixed forests of larch was calculated by the actual stand state calculation formula,and the stand status level was determined.In addition,the growth status of larch in two different mixed forests was also analyzed.【Result】The results showed that the mixed forest of larch had good spatial structure and age structure,and the value of the stand status index was 1 and reached the optimal stand status standard.However,due to the lack of tending and thinning,the density of forest stands is crowded,the stand is not updated well,and the proportion of healthy forests is low.The distribution of indicators such as stand density,stand renewal and forest health is zero,which seriously affects the actual forest status level.The indicators of stand composition,stand growth and top tree species competition are all around 0.5,and the stand value of forest stand is lower than 0.5,indicating that the two forest types are relatively single;the stand value of forest stand growth and top tree species is higher than 0.5,indicating that the stand is growing well,and the target tree species is the main advantage.By calculating theωvalues of the two forest types,it is found that both forest types are in a poor state of actual forest stand.Therefore,a reasonable forest management plan is formulated,and the forest stand density is adjusted through measures such as tending and thinning to improve the stand update.Increasing the proportion of healthy forests will help improve the overall quality level of the stand.Larch has different growth states when mixed with different tree species,so targeted forest adjustment is equally important to improve forest quality.【Conclusion】This study can provide a theoretical basis for forest management decision-making in the mixed forest of larch and birch and the mixed forest of larch and Mongolian Oak in the area of Daxing’an Mountains.