帽儿山天然次生林区色木胸高断面积生长模型的研究

根据系列调查资料,分析比较多个单木竞争因子,用回归分析法建立了帽儿山天然次生林区色木(Acermono Maxim.)单木生长模型。研究结果表明:所选的常用的单木竞争指数与天然次生林下生长的色木的胸径生长量相关不显著,而对象木相对直径(RD)、竞争压力指数(CSI)等指标与胸高断面积定期生长量存在比较明显的相关关系。     

黔中喀斯特次生林主要经营树种冠形特征及模型拟合

经营树种冠层结构调整是次生林经营的重要内容,而树冠结构不同往往表现在冠形特征差异,因此,研究冠形特征并进行模型拟合,对森林经营具有重要的理论和实践意义。以黔中喀斯特次生林封山造林、封山抚育、封山改良3种经营类型为研究对象,针对柳杉、猴樟、厚朴、喜树和光皮桦5个经营树种,使用1 221株实测数据,拟合冠幅、冠长、伸展度、冠长率、圆满度、投影比6个冠形指标与林木胸径和树高因子间关系。研究表明:(1)树种的实测因子与树冠结构特征多呈极显著正相关关系,建立实测林木因子(易获取因子)与树冠结构特征间的回归预估模型可行;(2)建立了黔中喀斯特次生林5种经营目标树的CW∝DBH、CL∝H的最优预估方程,树冠圆满度的拟合度要优于其投影比、树冠伸展度和冠长率;(3)柳杉、猴樟、厚朴、喜树和光皮桦的冠幅拟合解释量依次为0.62、0.69、0.77、0.59、0.77,冠长解释量依次为0.88、0.90、0.78、0.89、0.64。各拟合最优模型的胸径使用范围分别为1.6~18.3cm、0.5~8.5cm、1.8~6.5cm、0.8~13.0cm、0.7~25.8cm,树高适用范围分别为2.0~10.9m、1.5~8.2m、2.6~6.6m、1.5~12.1m、1.6~14.5m。因此,基于胸径、树高对各经营树种的冠幅、冠长预估模型适用于早期,中后期经营还需重建中后期的模型。     

帽儿山天然次生林主要阔叶树种叶量分布模拟

2007年,在黑龙江省帽儿山林区,设置30块天然次生林固定标准地,获取10个阔叶树种176株解析木,总共测量3 401个活枝条的叶生物量.建立10个阔叶树种的单木模型来预测活树冠内叶量的垂直分布,用3参数Chapman-Richards方程来估计叶量在树冠内相对高度处的累积叶量分布.参数估计的结果表明:在α=0.05的置信度下,相关系数都超过0.91,白桦达到0.98;水曲柳冠内最大叶量出现在最高位置0.82 CL(冠长)处,最低的是黄菠萝,出现在0.52 CL处;其他树种分布在这个区间之内,白桦为0.66 CL,柞树为0.78 CL;天然次生林阔叶树种的叶量在树冠的上部(0.3 CL以下)所占比例很小,在树冠的中部以及中下部(0.4 CL-0.8 CL)叶量所占比例最大,几乎集中了整个树冠60％ ～ 70％的叶量,其中,白桦达到72.22％,杨树达到72.55％,水曲柳最低为57.51％,而在树冠的下部(0.8 CL以下),几乎占很少的叶量,大约10％左右.本研究提出的这种累积叶量分布模型可以应用于采伐设计、合理的间伐收获方法和不同收获生产中的林分营养物质消长预估.     

帽儿山地区次生林椴树单木胸高断面积生长模型的研究

应用帽儿山天然次生林区不同林分条件下选设的20块椴树（Tilia amurensis）固定样地的解析木调查资料,分析多个单木竞争指标与对象木胸高断面积定期生长量的相关关系,在椴树单木胸高断面积生长模型中引入林木自身大小、单木竞争指标和立地因子,应用回归分析法建立帽儿山地区天然次生椴树单木胸高断面积生长模型。研究表明：天然次生林下椴树的胸高断面积定期生长量与对象木相对直径（RD）和竞争压力指数（SCI）等指标存在比较明显的相关关系。应用主分量线性组合的方法构造的综合竞争指标（MCI）包含了各竞争指标与胸高断面积生长量之间的绝大部分的相关信息,可以作为竞争指标应用于单木胸高断面积生长模型。     

基于岭回归和人工神经网络估测森林可燃物负荷量

选取东北林业大学帽儿山实验林场为研究区域,以少量野外定位调查数据及与其对应的遥感和GIS信息为基础,利用岭回归和人工神经网络分析方法,对森林可燃物负荷量估测模型及其影响因子进行系统研究。结果表明:对于TM3、TM(4×3)/7、TM4/3、海拔等10个影响可燃物负荷量估测的主要因子,利用岭回归方法可以克服变量间由于存在复共线性关系对求解待定参数所造成的不利影响。建立以像元为单位的岭回归和岭回归与神经网络组合估测模型,模型平均绝对百分比误差分别为17.6%和11.7%,2种方法可用于实现特定林场尺度森林可燃物负荷量的定量估测,其中组合模型效果较好。     

利用复位样木建立湿地松二元材积生长率动态模型

本文根据永丰县森林资源连清复查湿地松样地中1320株复位样木资料,运用动态模型的理论,以山本式P_v=C_0·D~(C_1)·A~(C_2)为基本框架,分析了参数C_1、C_2与D、A的相关关系,建立了以胸径和年龄为解释变量的二元材积生长率动态模型。经收集1023株检验样木适用性检验表明:该动态模型具有精度高、稳定可靠的特点,不但能充分利用样木信息,而且其参数能对样木信息资料所反映的客观规律作出解释。模型可在研究区域范围内推广使用。     

帽儿山林场椴树林树高曲线模型研究

基于东北林业大学帽儿山实验林场30块样地中724株椴树样木的胸径和树高数据,采用统计软件对常用的树高曲线模型进行了拟合,选择得出该地区的椴树林最优树高曲线模型。     

杉木人工林树冠表面积及体积模型的研究

以福建杉木Cunninghamia lanceolata人工林为研究对象,基于15块样地的33株标准木的解析数据,探讨了树冠平均表面积、最大表面积、平均体积、最大体积4个复合指标的预测模型。结果表明:4个树冠复合指标与胸径、树高、冠长、冠幅之间呈显著相关,相应的增加变量可提高模型的拟合精度,但当模型变量增加到2个以上时,模型精度提高不大。模型检验结果表明,以冠幅和冠长为变量的树冠表面积模型为最优;树冠体积以冠幅、冠长和树高为变量的模型为最优。模型的预估精度P均大于70.3%,说明模型可以较好地预估杉木人工林的树冠表面积和体积。     

太行山区栓皮栎天然次生林树高模型构建

以太行山区栓皮栎天然次生林为研究对象,以65块标准地及40株解析木为数据源,构建了优势木平均高神经网络模型和传统的函数曲线模型。结果表明:太行山栓皮栎天然次生林适宜的人工神经网络模型结构为1∶2∶1。与传统函数曲线模型相比,人工神经网络模型具有不依赖现存数学函数,拟合精度高等优点,更适合用来建立林分生长模型。     

东北天然次生林阔叶树种枝条基径模型

树冠是树木的重要组成部分,研究树冠结构是定向培育森林的技术手段,目前树冠模型常采用枝解析的方法。该研究用帽儿山地区天然次生林10个阔叶树种的枝条解析数据建立树冠结构相关的模型,提出了一种模拟阔叶树种枝条基径的模型,用逐步回归拟合枝条基径与总着枝深度、胸径、树高、冠幅、冠长之间的多项式回归关系,相关指数在0.9以上。模型检验结果表明冠长与着枝深度的组合对模型贡献率较小,白桦和椴树的相关指数较小。该研究对抚育整枝提供理论指导,为森林经营措施的优化提供技术支撑。     

Armillaria ostoyae in managed coniferous forests in Kastamonu in Turkey

Although several Armillaria species have been reported in Turkey, there is little information about their ecology in Turkish forests. In this study, we investigated five forest stands, approximately 5–74 ha in size, in Kastamonu province in the Black Sea Region of Turkey for the presence of Armillaria species in stumps and logs. The stands were mixed Abies nordmanniana ssp. bornmülleriana and Pinus sylvestris forests managed using a selective cuttings system; the proportion of fir in the total number of stems and stumps ranged from 36 to 98%. Based on sequence analysis of the internal transcribed spacer and intergenic spacer regions of the rDNA, all rhizomorphs sampled from the stumps and logs were of Armillaria ostoyae. The size of the genets was estimated with random amplified microsatellites analysis of the isolates and ranged from single stumps to approximately 450 m². One to seven genets were found in each stand. These results indicate that the genets had arisen from spores and vegetative spread was limited on most sites.     

上海中央公园特大银杏树白蚁防治探讨

通过对上海松江中央公园内65株特大银杏树白蚁为害情况的调查,发现该公园银杏受害率为100%,其中存在活白蚁的银杏占总量的56.9%,采用毒土处理、粉剂疗法、建立白蚁监测点等措施,经过两次灭杀,活白蚁的灭杀率达到92.3%和93.3%,从而使存在活白蚁银杏树的比例从56.9%下降到2.7%,白蚁发生情况明显降低。       

我国食品中农药残留研究进展

随着人们安全健康意识提高,食品中农药残留问题更加受到重视,本文综述了样品预处理研究进展及农药残留快速检测技术研究进展,并简单分析介绍各种方法的优缺点。     

建平半干旱地区石质山地造林技术研究

研究了不同植物在石质山地的造林成活率、土壤化学性质随造林年限的变化和造林措施对土壤化学性质和植物胸径、树高年净生长量的影响。结果表明：不同植物在石质山地的成活率在21%～85%之间,其中白榆和沙打旺的成活率分别为81%和85%,而小叶杨、刺槐、栾树的成活率均在70%左右;植被能明显提高石质山地不同土层的有机质、全N、P2O5含量,但提高程度随土层深度、养分种类和造林年限的不同而不同;在同一土层,生物复合肥料、菌剂和保水剂均显著提高土壤有机质含量（p〈0.01）并显著降低土壤P2O5含量（p〈0.01）;只有保水剂可引起土壤全K含量的明显升高;生物复合肥料、菌剂和保水剂均显著提高白榆、小叶杨、刺槐、栾树树高和胸径的年净生长量,但保水剂的提高程度最高。     

植物DNA甲基化研究进展

植物经常暴露在各种生物和非生物的胁迫之下,这些胁迫会影响植物的生长发育和繁殖并最终导致植物死亡。为了抵御不利的环境条件,植物已经进化出复杂而精细的网络来感知胁迫并激活防御系统。为此,植物激活许多信号转导通路,这些信号转导通路可以改变一些胁迫响应基因的表达,从而引起植物形态、生理和生化的改变以适应逆境。DNA胞嘧啶甲基化是高等真核生物的主要表观遗传机制之一,在维持基因组稳定性和调节基因表达方面起着关键作用。表观遗传变异比遗传变异更为灵活。一旦环境条件发生变化,为了适应新的环境植物都会发生表观遗传的改变。许多研究表明DNA甲基化参与植物的发育和应激反应。基于相关研究对DNA甲基化进行了综述,对植物逆境胁迫有重要意义。     

木材碳封存研究进展

碳封存可以分工业封存和生物封存, 工业封存包括地质封存、海洋封存、矿石碳化以及工业循环利用, 这些方法能快速回收CO₂, 但工艺流程技术复杂, 成本较高。木材碳封存是生物碳封存的一种类型, 树木光合作用吸收的碳主要存贮在木材中。运用木材密度、微密度等检测仪器, 通过确定木材密度变化, 结合其含碳率来计量木材的碳封存过程以及封存过程中碳的分配格局, 同时研究其与环境因子的相关性, 可以为研究森林的碳吸收动态提供便捷的方法和科学的依据。     

Tree regeneration in patch cutting in Norway spruce stands in northern Finland

The study focused on the success of regeneration on patch cuts in spruce-dominated stands in terms of stocking and tree height. It was based on an experiment in the Kainuu region in northern Finland. The experimental design included 8 stands with 58 clearcut patches of variable size (0.09–0.37?ha), on which either natural regeneration without site preparation or site preparation and planting of Scots pine was applied. A regeneration survey was conducted 13–15 growing seasons after treatments. Patches without site preparation had been restocked quite well from natural seed sources. The average number of trees was about 11,000?ha^?1, of which 1700?ha^?1 crop trees. With site preparation and planting, the stocking levels were also very high, 25,000 and 2100?ha^?1, respectively. One hundred percent of the planted patches and 75% of the naturally regenerated patches had an acceptable density. Restocking was equally good across the range of patch sizes. Tree growth had been somewhat slower in the smallest patches than in the largest ones in the range. Natural regeneration was capable of yielding good regeneration results in most patches, especially when site preparation was applied. Stocking levels and height development were higher yet in the planted patches.     

Changes in micropores in dry wood with elapsed time in the environment

To investigate the changes in microstructures of wood with elapsed time in the environment, CO₂ adsorption onto dry wood was measured at ice-water temperature (273 K) for samples aged from 0.1 years to over 1000 years. The micropore size distribution was obtained using the Horvath-Kawazoe method. Micropores smaller than 0.6 nm in wood decreased in number with elapsed time in the environment, and a negative correlation was found between cumulative pore volume for pores smaller than 0.6 nm and elapsed time in the environment. Cumulative pore volume in the 1000-year sample was almost half of that in the 0.1- year sample. Micropores smaller than 0.6 nm in wood with a few decades or more of elapsed time increased in number after rewetting and drying. Consequently, microstructures of wood with longer time elapsed in the environment were considered to be more stable, because of longer-term thermal motion and possibly more repeated moisture adsorption and desorption and/or temperature variation in the environment.     

Natural regeneration in patch clear-cutting in Picea abies stands in Southern Finland

Abstract

The success of natural regeneration on patch clear-cuts in Norway spruce stands in Southern Finland was examined in terms of stocking and tree height. The experiment was established in mature spruce stands in the submesic Myrtillus (MT) site type. In each of the eight study sites, three plots were treated with clear-cutting and planting, clear-cutting with partial tree retention and planting, and patch clear-cutting without site preparation, respectively. In three of the study sites, one plot with patch clear-cutting and site preparation was established. Each plot was 1 ha, out of which three patches of 40×40 m were clear-cut in the patch treatments. 10–11 years after cutting, the patches had on average 1316 crop trees ha^–1, of which 91% were spruces. Some 27% of the stands were up to the target stocking level (≥1600 ha^?1), and 36% were at least satisfactory (≥1300 ha^?1). Site preparation did not yield greater stocking levels on patches, but that result is ambiguous due to a difference in initial stocking. The average spruce tree height in the patches (0.76 m) was much smaller than in the case of clear-cutting and planting (2.42 m). In conclusion, the patches had been restocked tolerably well with spruce and birch for practical purposes during the 10- to 11-year period, but the regeneration process had been very slow compared to clear-cutting and planting.