Growth Index Measurement and Family Type Classification of Acacia mearnsii Plantation

Growth indexes of 47 7-year-old progeny forests of Acacia mearnsii in Huangmian forest farm were measured. A. mearnsii plantation was managed for producing both tannin and timber, and considering the tannin yield and timber volume growth index, the family types fall into superior family type(the superior type), to-be superior type(the medium type), and preliminarily eliminated type(the elimination type). Eight superior families can be used for production, namely No.169, No.114, No.177, No.32, No.3, No.145, No.158 and No.134.

Designing near-natural planting patterns for plantation forests in China

Background: China has a long tradition of managing planted forests. Different species of Populus, Eucalyptus, Larix, Cunninghamia and Pinus are planted to satisfy the local demand for wood products and provide ecological services at the same time. Evidence of the greater resilience of natural forests provides the motivation to develop asymmetric planting patterns, which is the focus of this study. We present a new method for designing plantation patterns that follow those observed in natural ecosystems and to maintain some regularity for operational convenience. Methods: Based on the uniform angle index, we analyzed the spatial structure of six natural forests in different regions of China. The uniform angle index describes the degree of spatial uniformity of the n nearest neighbors of a given reference tree. Accordingly, we identified all possible patterns of a neighborhood group within a regular planting pattern and developed a method to optimize planting point arrangements that contain some randomness as well as a minimum degree of regularity. Results:(1) There are 13 types of structural units in a regular planting, including seven random units, five even units and one cluster unit;(2) Five near-natural arrangements are presented with a minimum proportion of 50% of random units. These five arrangements represent a combination of regularity for operational convenience and asymmetry. Conclusions: The new planting patterns developed in this study are expected to increase the asymmetric competition and resilience of these important ecosystems. Some experimental plantings, based on our findings, have already been established, e.g., in Pinus tabulaeformis plantations in Tianshui, Gansu Province, and in a Populus deltoides plantation in Fangshan near Beijing.

Effects site conditions on industrial fiber plantations of Lar/x olgensis

Plot sampling was conducted in the second cultivation areas ofLarix olgensis in Heilongjiang Province, China. By analyzing plot investigation data, wood properties, and kraft pulps of 840 plots and 248 sample trees in industrial plantations of L. olgensis on different sites, we examined the growth process of L. olgensis industrial plantation with suitable structure, the wood fiber feature, chemical composition, physical performance and pulp characteristics. It is suggested that site conditions have major effects on plantation growth, fiber contains, fiber length, rate between fiber length and fiber width, pulping rate and pulp physics intensity. The best site for L. olgensis industrial plantation growth is site class Ⅰ and site class Ⅱ, which are on lower locations. Site condition has an obvious influence on the wood characteristics. Within the range of site conditions and stand densities studied, the worse the site condition, the less the fiber contains, the shorter the fiber length, and the more the 1% NaOH extraction. This kind of relationship becomes more obvious as stand age increases. However, the influence of site condition on pulping rate and pulp physics intensity is not obvious. The result provides theoretical base for cultivation of industrial fiber plantation of L. olgensis.

THE CONSTRUCTION OF SOME FORESTRY TABLES FOR DAHURIAN LARCH PLANTATIONS

Several growth models were selected to fit data of dahurian larch plantations using nonlinear regression analysis. The best models were used to construct the site index table' the 2-way volume table and the growth process table. The Chapman-Richards equation is the best model used as the guide curve to form the site index table for dahurian larch plantations.

A weeding-duration model for Abies sachalinensis plantations in Hok-kaido, northern Japan

I developed a weeding-duration model for Sakhalin fir （Abies sachalinensis （Fr. Schmidt） Masters） plantations that employs a generalized linear model. The number of years following planting that weeding is necessary is the response variable, and elevation, slope steepness, maximum snow depth, annual precipitation, geology, soil, site index, slope aspect, and vegetation type are explanatory variables. Among the explanatory variables, geology, soil, slope aspect, and vegetation type are categorical data. A Poisson distribution is assumed for the response variable, with a log-link function. Elevation, slope steepness, maximum snow depth, annual precipitation, site index, and vegetation type had a significant effect on weeding duration. Among the eight models with the smallest Akaike information criterion （AIC）, I chose the model with no multicollinearity among the explanatory variables. The weeding-duration model includes site index, maximum snow depth, slope steepness （angle） and vegetation type as explanatory variables; elevation and annual precipitation were not included in the selected model because of multicollinearity with maximum snow depth. This model is useful for cost-benefit analyses of afforestation or reforestation with Abies sachalinensis.

Comparative regeneration status in a natural forest and enrichment plantations of Chittagong (south) forest division, Bangladesh

The natural regeneration of the tree species in pure natural forest stand and enrichment plantations of Baraitali Forest of Chittagong (South) Forest Division, Bangladesh was studied by stratified random quadrat method during April 2002 to November 2002. Totally 100 plots of 3 m X 3 m in size represents a total of 64 regenerating tree species from natural forest with an average seedlings of 24767/hm2, while only 40 regenerating tree species were recorded from enrichment plan-tations with an average seedlings of 18633/hm2. Maximum regeneration in natural forest was found with Castanopsis spp. (2200 seedlings/hm2) followed by Glochidion lanceolarium (2183 /hm2) whereas, in enrichment plantations maximum regen-eration was found with Dipterocarpus gracilis (2117/hm2) followed by Anogeissus acuminata (2000/hm2). For natural forest, highest relative density was found for Castanopsis spp (8.88%), relative frequency for Glochidion lanceolarium (7.36%), rela-tive abundance for Syzygium spp. (3.79%) and Importance Value Index were recorded with Glochidion lanceolarium (18.24%). The corresponding values for enrichment plantations were highest with Dipterocarpus gracilis (11.36%), Glochidion lanceo-larium (9.71%), Dipterocarpus gracilis (5.92%), Glochidion lanceolarium (23.32%) respectively. Stem per hectare of some common trees with their seedlings and saplings in both the natural stands and enrichment plantations showed that only Dip-terocarpus gracilis successfully recruited in both sites but recruitment was higher in natural forest. Like many other primary rain forests, the Baraitoli forest typically has both substantial seedlings and soil seed bank from which regeneration may occur. The naturally regenerated seedlings are quite dense but it could not reach the pole stage due to human interference.

Site Productivity of Clone and Seed Raised Plantations of <i>Eucalyptus urophylla</i>and <i>Eucalyptus grandis</i>in Southeast Mexico

The relationship between soil variables and forest productivity of Eucalyptus urophylla (Eu) and E. grandis (Eg) was studied in commercial forest plantations (CFP) in Huimanguillo, Tabasco, Mexico. The group of Eu included seed and clone raised plantations and the Eg group included only seed raised plantations. Tree measurements and soil sampling were carried out at 56 500-m2 plots. Two soil depths (0 - 20 and 20 - 40 cm) were sampled and analyzed for physical and chemical properties. Site Index (SI), calculated at year 14 was used as indicator of forest productivity. Simple correlation, multiple and second order regressions were used to test the effect of soil variables on productivity. Results showed that mean annual increments (MAI) of Eu and Eg were comparable to other regions of the world reaching 49 m3·ha-1·y-1 across a range of low to high soil fertility gradient (15 to 80 m3·ha-1·y-1). For both species, regardless of the production method (seed or clone), soil texture was the most relevant variable to explain variation in productivity. Eu productivity was correlated to exchangeable Mg (0.3) and Al (0.3) in the 0 - 20 cm soil depth and CEC (0.4) and exchangeable Al (0.6) in the 20 - 40 cm soil depth. Compared to clone plantations, seed plantations showed higher correlations between soils properties and productivity. Aluminum saturation was negatively related to Eg productivity. The highest correlation between soil and productivity were found for Eg, with soil P-availability and aluminum saturation explaining 82 and 85% of the variation, respectively. This works shows that low fertility soils, previously used as pasturelands can be productive for forest plantation purposes and contribute to carbon sequestration.

Structure Parameters and Physiological Indices Research of High-quality and High-yield Apple Orchards

In order to research environment parameters and physiological indices of high-quality and high-yield apple trees, two orchards with young and mature apples trees were investigated to explore structural parameter of apple tree and community, and some physiological indices in fields and by room measurements. The results showed that tree height of high-quality orchard was in the range of 260 to 290 cm, branch angle in 70°-75°, and orchard coverage rate in 75%-94%, and the connec-tion rates between rows and trees were lower. Furthermore, the total branches of mature orchard reached 1.04 ×106 per hm2, while the young orchard was 8.79 ×105 per hm2; the leaves were thick and chlorophyl content was high, with SPAD value at 58.22. Additional y, the photosynthesis of the orchard was strong, and net photo-synthetic rate was 17.48-21.8 μmolCO2/（m2·s）. The proportions of lateral shoot of bearing part were 81% and 75% respectively.

湖北杉木人工林生物量及其可变密度预估模型研究

利用6~59年生杉木人工林190个标准地资料和517株样木生物量测定数据,以建立的单木生物量估算方程为基础推算出各林分单位面积生物量,并基于林龄、立地指数以及7种不同林分密度指标构建并选择最优的全林分生物量预估方程,研究湖北杉木人工林林分生物量及其变化规律。结果表明:该区域杉木人工林平均单株生物量为52.8893 kg,以胸径和树高为变量的二元单木生物量方程的拟合优度为0.91,其拟合优度和精度更高;林分平均单位面积生物量为101.4923 t/hm^(2),总体上呈随林龄增加而增大的趋势;基于多元回归技术的经验方程构建了含7个林分密度指标和不含密度指标共计16种林分生物量预估模型,包含林分立木株数和林木大小信息的林分密度指标的模型均达到了较理想的拟合效果,其中密度指数SDI的Schumacher修正收获模型精度最高,确定系数为0.95,检验精度为97%,对本区域杉木生物量估算具有较好的适用性,能为其人工林经营和质量提升提供参考与支持。

宁夏六盘山北部华北落叶松林树高与胸径生长的多因子响应耦合模型构建

【目的】分析宁夏六盘山半干旱区叠叠沟小流域华北落叶松人工林林龄、密度和主要立地因子对树高和胸径生长的影响,建立树木生长的多因子响应耦合模型,为该地区华北落叶松人工林生长预测和可持续经营提供理论依据。【方法】2018和2019年,在六盘山半干旱区叠叠沟小流域分别选择42和57块华北落叶松人工林样地,调查树高、胸径、林龄、密度等林分结构特征以及坡向、土壤厚度等立地因子,并收集2003—2017年在叠叠沟小流域调查的93块样地历史数据。基于192块样地数据,分析树高和胸径对林龄、密度、坡向、土壤厚度等因子的响应规律,利用2/3和1/3的数据建立和验证树高与胸径生长的多因子响应耦合模型。【结果】树高和胸径对林龄、密度、坡向、土壤厚度的响应规律各异;树高和胸径随林龄增加先快速增加,后在林龄超过20年时缓慢增加;树高和胸径随密度增加先表现为稳定,后在密度分别超过2000、1500株·hm^(-2)时缓慢下降,在密度超过3000、2300株·hm^(-2)时加快下降;树高和胸径随坡向偏离正北方向的角度增加先表现为稳定,后在坡向超过80°时迅速降低;树高和胸径随土壤厚度增加先表现为增加,后在土壤厚度分别超过90、80 cm渐趋稳定。基于连乘耦合、立地指数和立地因子3种林木生长模型表达式,建立树高和胸径响应林龄、密度、坡向、土壤厚度和立地指数的耦合模型并拟合模型参数;树高模型的确定系数分别为0.804、0.902、0.806,NS系数分别为0.793、0.903、0.762;胸径模型的确定系数分别为0.846、0.803、0.834,NS系数分别为0.837、0.840、0.818;3种模型拟合效果均较好。【结论】宁夏六盘山半干旱区华北落叶松人工林树高和胸径生长随林龄、密度、坡向、土壤厚度增加分别表现为先快后慢增加、先稳定后下降、先稳定后降低、先升高后稳定,建立的连乘耦合、立地指数和立地因子多因子耦合模型精度均较高,但鉴于研究区尚未确定立地指数分布规律并综合考虑各模型精度、应用难度、结构复杂程度差异,建议采用多因子连乘耦合模型预测华北落叶松人工林树高和胸径生长。

云南省西双版纳勐腊县橡胶林下植物多样性分析

为探究云南省勐腊县橡胶林下植物物种组成及多样性等基本情况,对勐腊县内94个橡胶林下植物样方(20 m×20 m)和20个土壤样方进行调查,分析环境、空间因素对林下植物物种分布和植物多样性影响情况。结果显示:勐腊县橡胶林下植物共计87科、197属、300种,优势物种为银柴(Aporusa dioica)、阔叶箬竹(Indocalamus latifolius)、葛藤(Pueraria lobata)等;20个土壤样地中,全氮、全磷、全钾等成分均存在中程度变异,其最高含量分别为1.0927%、0.1726%、2.6499%。对植物物种及优势物种分布影响因素分析(RDA)表明:地形对优势物种分布显著影响;土壤全磷和坡度对植物物种分布达到极显著影响(P<0.01)。在植物多样性分析中,坡度对植物多样性影响显著高于其他影响因子(P<0.05),辛普森指数(Simpson,D)和香农指数(Shannon-Wiener,H)在坡度大于35°时最高,并且在回归分析中拟合度较高;海拔大于600 m时,Simpson指数和Shannon-Wiener指数较高,物种丰富度(S)在600~700 m整体高于其他海拔梯度;橡胶树(Hevea brasiliensis)在8~14树龄时,植物物种丰富度最高。勐腊县橡胶林下植物物种较丰富,但受人工干扰影响导致植物多样性较差,如果通过合理的管控会使橡胶林下植物多样性变高,有助于生态恢复。

基于YOLOv8的陕西黄土高原刺槐林枯立木识别

黄土高原在生态恢复的过程中由于不适宜造林加之极端干旱频发,导致人工刺槐林出现退化甚至死亡,从而产生枯立木。为准确识别陕西黄土高原刺槐林枯立木,进而分析其空间分布格局,本研究以典型人工林刺槐为对象,沿陕西黄土高原降水梯度设置6个样地,利用无人机获取刺槐林高分辨率RGB影像,结合多个深度学习目标检测模型识别刺槐林枯立木,通过对比与分析证明了YOLOv8模型在检测效率以及检测精度方面的优越性。通过对刺槐林数据集训练与测试以及刺槐林RGB影像的拼接,从而分析刺槐林枯立木的分布格局,用枯立木指数(SDTI)反映刺槐林退化程度,同时分析了坡向对其影响。YOLOv8模型训练后平均帧率FPS达到了68.7帧/s,且其验证集平均精度均值(mAP)达到了94.6%,F1得分为0.92,均好于其他模型。综合不同目标检测模型的各项主要评价指标及泛化能力,选择YOLOv8模型分析刺槐林枯立木分布格局,表明陕西黄土高原刺槐林SDTI随降水梯度递减呈递增趋势;不同坡向SDTI呈阳坡>半阳坡>半阴坡>阴坡的变化规律。本研究可为黄土高原刺槐林退化程度评估及其合理的经营管理提供科学依据。

吉林省水曲柳人工林立地指数表的编制

本文以吉林省125块水曲柳人工林样地的625株优势木作为研究对象,建立树高-年龄模型,编制立地指数表。结果表明:在12个生长模型中,逻辑斯蒂模型H=24.6257/(1+6.6019e-0.0901 A)拟合效果较好(R 2=0.9611,AIC=2598.714),通过计算各龄阶树高标准差(S)和变异系数(CV),确定了基准年龄(A 0)为40年,指数级距1 m,划分6个指数级距,运用标准差调整法编制立地指数表,落点和卡方检验表明,所编制的立地指数表精度较高,能够客观地评价吉林省水曲柳人工林的立地质量。

北京油松人工林生长对密度和立地的响应

采用样地调查和树干解析方法,研究北京山区不同林分密度和立地条件下油松人工林生长规律,分析林木生长过程对密度、郁闭度和立地的响应关系。结果表明:胸径、树高、材积生长量与密度、郁闭度呈负相关,与立地指数呈正相关;高密度林分胸径、树高连年生长量与平均生长量相交时间比低密度林分提前约3 a,抚育起始期范围在15~21 a;根据材积连年生长量和平均生长量交点可知,研究区油松人工林在40~45 a达到数量成熟;在开展油松人工林经营过程中,确定抚育间伐起始期需同时考虑林分密度和所处立地条件,以更好促进保留木健康生长,同时应在林龄达到40 a前确定最终保留的目标树,以实现森林全周期可持续经营,为指导油松人工林经营提供参考依据。

马尾松林叶面积指数季节动态的测定

【目的】评价光学仪器法测定马尾松林叶面积指数(LAI)的精度,为准确监测马尾松林LAI季节动态提供技术支持。【方法】以凋落物法测定值代表马尾松林真实的LAI,对展叶调查、异速生长方程法和光学仪器法(半球摄影法和LAI-2200植物冠层分析仪)获取的马尾松林LAI季节动态进行评估,并量化不同因素包括集聚指数(ΩE)、木质比例(α)和针簇比(γE)对光学仪器测定值的影响。【结果】马尾松林内主要树种的平均叶寿命为1.53~1.94,比叶面积(SLA)差异较大(99.15~278.33 cm^(2)/g)。不同方法测定马尾松林LAI的季节动态均呈单峰形变化模式,且在7月达到峰值。在各调查时期,凋落物法的测定值与异速生长方程法的测定值差异不显著。半球摄影法测定的有效叶面积指数(Le)比凋落物法、异速生长方程法的测定值分别低估了49%~64%和47%~61%;LAI-2200植物冠层分析仪法测定的Le低估了25%~44%和20%~42%。半球摄影法测定的Le经自动曝光、α、ΩE及γE校正后,精度明显提高,比凋落物法、异速生长方程法平均低估了8%和5%;LAI-2200植物冠层分析仪法测定的Le经α、ΩE及γE校正后,其精度大幅度提高,比凋落物法、异速生长方程法平均低估了6%和2%。【结论】考虑影响光学仪器法测定LAI的因素后,半球摄影法和LAI-2200植物冠层分析仪法测定的LAI精度得到明显提高,表明两种光学仪器法均能相对准确地测定马尾松林LAI的季节动态,可为不同区域马尾松林LAI季节动态的研究提供方法参考。

杉木人工林林分空间结构分析及综合指数评价

基于广东省羊角山林场、连山林场和金鸡林场9个杉木人工林样地的实测数据,对杉木人工林林分空间结构参数进行评价和分析,为优化和调整杉木人工林的林分空间结构奠定基础。采用角尺度、混交度、大小比数、开敞度和竞争指数5个林分空间结构参数,分析不同龄组(幼龄林、中龄林、近成熟林)以及不同密度(1 700、2 000、2 300株/hm^(2))杉木林林分空间结构特征,通过熵权法构建林分空间结构综合指数。结果表明,9个样地的杉木林各龄组的角尺度处于均匀分布和随机分布状态之间;林分混交度普遍较低;杉木各龄组的大小比数都接近中庸状态,林木分化水平较低;开敞度在不同龄组间差异显著;竞争指数在3个龄级之间呈极小幅度的波动;不同龄组的林分空间结构理想程度为:中龄林>近成熟林>幼龄林;不同密度的林分空间结构理想程度为:低密度>中密度>高密度。以样地林分空间结构分析与评价为依据,采取合理的营林措施,可以使杉木人工林的林分水平分布格局逐渐趋向随机分布,混交状态逐渐趋向最高混交,林分竞争状态逐渐趋向优势态竞争,从而促进其可持续经营。

不同抚育间伐方式对平原生态林空间结构的影响

为探讨不同抚育间伐方式对北京市平原生态林林分空间结构的影响,在北京市通州区选取旱柳、国槐和白蜡等代表性林分布设9个固定样地。在选取目标树后,每个林分类型分别采取干扰木采伐、群团状采伐以及带状间伐,采用优化后的大小比数、角尺度和密集度3个常用的林分空间结构指标,分析平原生态林空间结构现状以及间伐对目标树及林分空间结构的影响。利用3个指标构建空间结构综合指数(CSSI)来综合评价不同间伐方式对北京市平原生态林空间结构的影响。结果表明:(1)CSSI结合了角尺度、密集度和优化后的大小比数,适用于北京平原生态林的空间结构评价。(2)以国槐、白蜡和旱柳为代表的平原生态林间伐前空间分布格局呈均匀分布,大部分林木呈中庸状态,林分比较密集,白蜡和旱柳的空间结构优于国槐。(3)抚育间伐能显著优化平原生态林空间结构,尤其对于国槐等保留密度较高的林分优化作用明显。(4)对于不同树种来说,改善空间结构的最优间伐方式不尽相同,但对于目标树空间结构单元来说,针对目标树的干扰树采伐优化程度最为明显。

Problems in Fast-growing and High-yield Plantation Ecosystem Management and Their Countermeasures in China

The paper analyzed the basic characteristics of fast-growing and high-yield plantation, classified and identified the ecological problems in its development, and finally proposed the basic principles and corresponding technical measures for fast-growing and high-yield plantation ecosystem management based on these problems.

Ecosystem-management-based Management Models of Fast-growing and High-yield Plantation and Its Eco-economic Benefits Analysis

The paper expounded the basic concept and principles of ecosystem management,and analyzed the state and trend of industrial plantation ecosystem management in other countries.Based on the analysis of typical case studies,the eco-economic benefits were evaluated for the management models of fast-growing and high-yield plantations.

不同森林恢复类型对南方红壤侵蚀区土壤质量的影响

为了探讨主要森林类型对土壤质量的影响 ,对南方红壤侵蚀区 4种主要森林恢复类型下土壤物理、化学、生物学性状进行了比较研究 ,结果表明 :不同的森林恢复类型导致了土壤物理、化学和生物学性质的显著差异。 4种森林类型的土壤质量均比长期干扰下对照的土壤质量高。人工林土壤质量又相对比天然次生林土壤质量低。其土壤质量综合指数分别为 :天然次生林(0 .95 )、油茶林 (0 .6 8)、杉木林 (0 .5 5 )、湿地松林 (0 .36 )、对照 (0 .0 4 )。自然恢复在恢复初期是提高土壤质量的有效途径。导致人工林和对照土壤质量相对较低的主要因素是 :周期性的森林抚育打破土壤物理结构、凋落物质量较低、凋落物量较低、微生物生物量较低、微生物功能较差和土壤养分流失严重。在土壤质量指标选择方面 ,土壤微生物生物量结合微生物功能多样性是反映土壤生物学活性和土壤质量的较好指标。