丝栗憷生长与生产力的研究

在福建省邵武市洪墩采育场，调查丝栗栲要标地１０块，做平均木、树干解析木９株，杉木人工林标地２块，研究丝栗栲的生长与生产力，结果表明：丝栗栲林的胸径、树高及单株材积总生长量，均随年龄的增加而增加；胸径２０ａ关生长最快，树高１６ａ前生长最快；材积３６ａ时尚未有下降的趋势。胸径、树高平均生长量，随年龄增加而增加，当生长量达高峰后，则随年龄的增加而下降；胸径生长高峰，好立地１２ａ，中、劣立地１５ａ；树主生     

宁化县闽粤栲造林效果分析

通过对宁化国有林场杉木与闽粤栲混交造林成效的全面调查,分析了现有林分的生长状况,探讨了不同立地质量等级、不同坡位、不同坡向、不同混交比例和不同混交方式等对闽粤栲及杉木生长的影响,结果表明：不同立地质量等级、坡位、坡向对闽粤栲胸径、树高生长和蓄积量影响显著,在立地条件较好的阴坡或半阴坡的中下部更适宜闽粤栲生长,胸径、树高、材积生长量较高。同时,杉木与闽粤栲混交造林,能够促进杉木生长,胸径、树高、材积生长量均超过杉木纯林,混交比例以杉木与闽粤栲3：1的比例生长量最大,混交方式则以带状混交的生长量最大,人工造林应大力发展混交林。     

常绿阔叶林主要建群树种林木生长规律的研究

常绿阔叶林是江西省地带性植被类型。本文分析赣南建群树种有丝栗栲、南岭栲、米槠、木荷、黧蒴栲,而赣东北为甜槠、木荷、丝栗栲、石栎。利用标准地平均木的解析资料,建立林木树高、胸径、材积潜在的生长量函数。拟合结果以理查兹曲线拟合效果最好,相关系数均大于0.9。     

尾叶桉短轮伐期经营林分生长研究

对尾叶桉短轮伐期经营林设置好、中、差三类立地调查林分生长及进行树干解析，以研究尾叶桉的生长情况。结果表明：立木平均胸径、平均树高及平均单株材积在三类立地的生长差异均显著，好立地的平均单株材积达到0．2410m^3，分别是中等、差立地的1．56倍和2．52倍。三类立地解析木胸径、树高、单株材积总生长量，均随着年龄的增加而增加，6年生胸径总生长量好立地达到19．95cm，分别是中等、差立地的1．24倍和1．50倍；树高总生长量6年生达到22．80m，分别是中等、差立地的1．17倍和1．27倍；单株材积总生长量达到0．3025m^3，分别是中等、差立地的1．82倍和2．85倍。3个指标的平均年生长量和连年生长量均有随着年龄增加而下降的趋势。了解短轮伐期林分林木生长的变化趋势，才能合理经营、维护地力和持续经营。     

湖北高密度杉木人工林生长规律研究

为研究湖北省高密度杉木人工林生长规律,对鄂东南地区高密度杉木人工林进行标准地调查,获取61块样地数据和183株解析木数据,建立了杉木单木树高、胸径和材积生长模型,根据拟合优度及残差指标,高密度杉木单木胸径和树高生长的最优模型选择理查德模型,单木材积最优模型选择考尔夫模型,所选模型检验精度均较高,达到拟合效果;通过绘制杉木胸径、树高和材积的生长曲线图,杉木生长量在初始阶段生长速率较大,单木树高和胸径生长量在第4 a达到最大值后逐渐下降,单木材积连年生长量在第10 a达到最大值;利用多元非线性回归建立关于杉木林分平均胸径、平均树高和林分蓄积与林龄、立地指数和林分密度的林分生长模型,选择的林分生长模型均通过检验;利用林分蓄积量的平均生长量和林分平均直径来确定高密度杉木林分的数量成熟龄和工艺成熟龄,在立地指数16～20 m和林分密度4 000～6 000株/hm~2时,杉木的数量成熟龄和工艺成熟龄分别为10～13 a、10～11 a,与湖北咸宁地区高密度杉木造林小径级采伐年龄相符。     

不同立地级杉木林间伐强度试验及经济效益分析

14年生不同立地级杉木林间伐强度试验结果表明 ,间伐强度对不同立地级的杉木树高生长影响不显著 ,而杉木胸径、单株材积和经济出材率均随间伐强度提高而增加 ,单位面积蓄积量和总出材量均随间伐强度加大而减小。不同立地指数级 (1 6、1 8)以中度间伐经济效益最高 ,其次是强度间伐 ,对照最低。     

尖峰岭绿楠树生长过程的研究

对海南尖峰岭地区３０年生的热带乡土树种———绿楠人工林进行了样地调查,并进行了样木横剖树干解析,研究其生长规律及与环境的关系。研究结果表明：（１）绿楠是比较速生的树种,地径、胸径、树高和材积的年生长都呈多峰态曲线;（２）胸径年生长高峰值出现在第１１年,而树高年生长量高峰期晚于地径和胸径生长高峰值出现的年份;（３）在生长初期（８ａ前）,材积生长极缓慢,年生长量＜００００９ｍ３,其后开始较快增长,到第１７年出现最大值０００８６８ｍ３;（４）从平均生长量看,地径变化比较平缓;胸径在１４ａ前呈稳态上升趋势,１４ａ后呈平稳发展状态并略有下降;树高在１９ａ前基本呈稳态上升趋势,１９ａ后保持在０５０ｍ／ａ左右,并呈缓慢地下降趋势;材积一直是随着年龄的增加而增加;（５）不同坡位的水肥等条件不同,因而影响了绿楠树的生长,离水沟最近的下坡地的树高和胸径比上坡分别大３７５％和２９１％;（６）绿楠树地径、胸径和树高的连年生长变化趋势基本上与降雨蒸发比（Ｒ／Ｅ）变化趋势相一致,说明水分状况是影响绿楠生长的一个重要环境因子。     

闽粤栲人工林生物量研究

利用树干解析计算分析福建省牛姆林自然保护区22年生闽粤栲人工林的生长量、生物量及生产力特征.结果表明:闽粤栲树高、胸径和材积总生长量分别达到16.5 m,19.5 cm和0.27 m3,期间分别出现3次、5次和2次生长高峰,其中,树高和胸径生长高峰出现年份一致,材积生长高峰出现相对滞后;树高、胸径连年生长量曲线与平均生长量曲线出现多次相交,材积各生长量曲线基本不相交且变化幅度相对较小;将闽粤栲树高、胸径和材积总生长量与林龄进行回归方程拟合,拟合效果理想;闽粤栲各器官生物量表现为干＞枝＞根＞叶,各器官含水率表现为根＞干＞枝＞叶,单株平均含水率为48.05％;闽粤栲种群生物量为295 261 kg/hm2,种群净生产力为13 420.95 kg/(hm2 ·a).     

杉木林下套种丝栗栲复层经营生长效应

在12年生杉木人工纯林中进行不同强度间伐后套种丝栗栲,对林分的生长效应进行研究,结果表明:现有杉木林间伐后,保留杉木1 110～1 350株/hm2,林下丝栗栲生长状况良好,而且能够促进上层保留杉木林木的生长,形成层次明显的复层林分。方差分析结果也显示,三种不同保留密度的杉木林分套种丝栗栲后,杉木单株材积生长差异达到显著或极显著水平,与对照的差异均达到了极显著的水平。杉木丝栗栲复层林分杉木单株材积明显增长,有利于培育杉木大径材,且保育了一定数量乡土阔叶树种,有利于改良土壤的理化性质,建议在闽西北林区适宜林分推广应用。     

杉木实生及无性系人工林生长规律的研究

通过测算杉木实生林与无性系林的生长因子数值,建立测树因子与林龄的回归模型,选取不同生长因子的最优生长模型,采用分层切割法及树干解析法对广西省苍梧县天洪岭林场23年生实生杉木林和21年生无性系杉木林的生长规律进行研究。结果表明,2种人工林的胸径、树高及材积总生长量都随着林龄的增加而增大;2种杉木人工林胸径、树高及材积的平均生长量和连年生长量呈现出波动式生长,从2种生长量曲线的走势上看,实生林的平均生长量和连年生长量曲线波动幅度较大,但无性系林的生长趋势要强于实生林。可见,杉木无性系的生长量比实生林更具优势,具有更高的生长稳定性和生长潜力,更符合杉木人工林"速生、丰产、优质"的培育目标。     

杉木人工林单木断面积生长动态模拟

应用面板数据固定效应模型对杉木人工林单木断面积生长规律进行模拟,在模拟过程中,将胸径(DBH)和活冠比例(LCR)作为自变量,又分别加入密度因子和不同类型的竞争指数,同时引入立地条件和林龄效应来解释单木断面积生长过程中的异质性。结果表明:虽然密度因子与竞争指数有较强的相关性,但是在单木断面积生长中都具有不可忽略的重要影响。立地条件与林龄对单木断面积的拟合偏差在不同的林分密度下略有不同,随立地指数或者林龄增加,其对平均单木断面积拟合偏差的影响也增大。     

Age structure and regeneration of subalpine fir (Abies fargesii) forests across an altitudinal range in the Qinling Mountains,China

Age structure and regeneration dynamics of subalpine fir (Abies fargesii) forest were studied across the altitudinal range in both the north and south aspects of the Qinling Mountains, China. Ages of individual fir trees were determined based on the number of rings counted from cores and the number of years to reach coring height estimated using age–height regression. Fir age structure and regeneration dynamics were similar in both the north and south aspects. A unimodal population age structure was found at the low- and mid-elevations in both aspects, indicating that environmental factors might play an important role in shaping A. fargesii age structure and regeneration at those sites. There was a recruitment pulse during the time period 1830–1890 at each altitudinal site, but no stem recruitment occurred at the low- and mid-elevations in the last century, which might be attributed to the intensive cover of understory bamboo. Fir trees were, however, persistently recruited at the upper limits during the last 150 years, and the fir tree density at the upper limits was significantly higher than that at the lower limits in both aspects. The fir population at the upper limits showed a significant increase in recruitment and stem density relative to the fir population at the low- and mid-elevations in the last century. We propose that the differences in recruitment might promote variations in stand structure and regeneration dynamics of the subalpine fir forests along the altitudinal gradient in the Qinling Mountains, China.     

柏类引种试验研究

对柏类４个树种墨西哥柏,绿干柏,垂柏,巨柏共１２个种源的引种表明,不同树种和种源树高,胸径增最大年份分别出现在造林后第４年和第５年;造林后１０ａ,lay status     

杉木林分密度效应研究

该项试验共分2个部分.(1)造林密度试验,小区面积为600 m2,5个处理,即1 667株.hm-2(A)、3 333株.hm-2(B)、4～983株.hm-2(C)、6 633株.hm-2(D)、9967株.hm-2(E);(2)造林密度调控试验,造林设计方法与造林密度试验相同,但在林分生长过程中,按密度管理图的密管线0.5为标准进行间伐,间伐后保留密度要与临近的下一个初植密度较稀植的林分密度基本相同,两者进行比较.试验结果(1)造林密度试验,优势高、平均高、平均胸径均随年龄的增加而递增,随密度的增加而递减,优势高9a、平均高6 a、平均胸径5 a,密度间差异已达显著性水平;林分蓄积量则随年龄增加而递增,5～7 a,密度间差异显著,8～18a,只有A密度与E、D密度差异显著;枝下高随密度、年龄的增加而递增,12～a后,C、D、E密度间的差异很小;冠幅随密度的增加而递减,随年龄的增加而递增,9～10a后,各密度则随年龄增加而缓慢递减.(2)造林密度调控试验,同一指数级,间伐后的林分与其密度基本相同未间伐的林分比较,其优势高、平均高差异不明显;立木蓄积前者小于后者;总蓄积(立木蓄积+间伐蓄积)前者大于后者;同一指数级,初植密度不同的林分,间伐后与密度基本相同未间伐林分的蓄积百分比,初植密度大的大于初植密度小的;指数级不同,而初植密度相同的林分,间伐后与密度基本相同未间伐的林分总蓄积百分比,高指数级的比值大于低指数级的比值.     

Growth reduction in harvest-age,coniferous forests with residual trees in the western central Cascade Range of Oregon

To evaluate the relationship of overstory residual trees to the growth of unmanaged young-to-mature understory Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) and western hemlock (Tsuga heterophylla (Raf.) Sarg.), the basal area and volume of 14 paired plots with and without residual trees were examined in the Willamette National Forest, Oregon. Residual trees were large survivors of the fires that initiated the understory between 55 and 121 yr ago. Understory stands were naturally regenerated and not managed in any way. High residual tree and understory densities were negatively associated with understory volume. The relation of density of residual trees to total understory and Douglas-fir basal areas and volumes was best described by a negative logarithmic function. The rate of decrease in total understory and Douglas-fir basal areas and volumes per individual residual tree became smaller with increasing residual-tree density. Predicted total understory volume reduction was 23% with five residual trees/ha and 47% with 50 residual trees/ha, averaging 4.6% and 0.9% per residual tree, respectively. After including the estimated volume growth of residual trees since initiation of the understory, stand volume was still 19% lower with five residual trees/ha and 41% lower with 50 residual trees/ha than in stands with no residual trees, averaging a reduction of 38% and 0.8% per residual tree, respectively. In mixed stands of Douglas fir and western hemlock, predicted Douglas-fir basal area and volume declined more rapidly than did total understory basal area and volume when residual-tree densities exceeded about 15 trees/ha. This difference was probably due to the relative shade-intolerance of Douglas fir. Predicted Douglas-fir volume reduction was 13% with five residual trees/ha and 75% with 50 residual trees/ha, averaging 2.6% and 1.5% per residual tree, respectively. The southern aspects had more than 150% the total understory basal area and volume and more than 200% the Douglas-fir volume and basal area of the northern aspects. Lower density and basal area of understory trees, particularly of dominant and codominant Douglas fir, were associated with increasing residual-tree densities. Given the same diameter at breast height (DBH), heights of Douglas fir were not related to residual trees. Regardless of understory age, understory volume was greatest in stands with the lowest understory densities. These results suggest that timber production in unthinned green-tree retention units may be reduced and may depend on the density of leave-trees. Thinning of understory trees is recommended to reduce growth loss from intraspecific competition.     

Dendroclimatological regions of Douglas fir (<Emphasis Type="Italic">Pseudotsuga menziesii</Emphasis> Franco) in western Poland

Abstract Six Douglas fir (Pseudotsuga menziesii Franco) stands were selected in both the Sudety Mountains and the Great Poland Lowland. These two regions are distinctly different with regard to thermal and pluvial conditions. In each stand, two increment cores per tree were extracted from 20 approximately 100-year-old trees and the tree-ring widths measured. It is clear from the different growth reactions of the study trees to the climatic conditions that the Sudety Mountains and the Great Poland Lowland are two dendrochronologically separate regions. The tree-ring width chronologies form homogeneous groups for each region. The tree ring–climate models for Douglas fir in both regions indicate similarities and differences. The similarities among chronologies are attributed to winter temperature. The differences are attributed to rainfall (which changes with longitude and altitude of sites) during the vegetation season.     

Growth and nut production of black walnut in relation to site, tree type and stand conditions in south-central United States

Black walnut (Juglans nigra) is a prime tree species for agroforestry practices in the United States providing highly prized wood and nuts for human consumption and wildlife. In 54 black walnut stands in south central United States, the site index (i.e., mean dominant height [DH], at age 25 years) ranged between 5.2 and 21.4 m, and was independent of stand density. There were no differences in height and stem diameter (DBH) growth rates between stands with improved varieties and native stock. Most stands were in a “free growth” stage because of either early age or wide spacing. Mean annual increments in DBH and height were positively related both for improved varieties and native stock. Understory competition had a substantial detrimental effect on DH. In a 26 year-old stand, trees growing within Kentucky blue grass (Poa pratensis) had a site index 5 m greater than trees growing within tall fescue (Festuca arundinacea). Predicted nut yields in 2002 varied between 0 and 1370 kg of hulled nuts per ha. Improved varieties had, in general, higher nut yields than predicted from a nut yield-DBH equation developed for individual trees. Nut yields were highly variable both within and among stands, and were related to DBH in native stock but not in improved varieties.     

坡位对杉木纯林生长的影响

通过对不同坡位7年生杉木纯林生长的调查与研究,结果显示:坡位对杉木纯林各生长指标均有显著影响;林分的平均胸径、树高、冠幅、枝下高、平均单株材积、单位面积木材蓄积量等生长指标一致表现为下坡位>中坡位>上坡位。坡位间以胸径和树高差异最为显著,下坡位林分平均胸径达到10.59 cm,高出中坡位的11.6%,高出上坡位的20.0%;下坡位林分平均树高为7.25 m,高出中坡位的16.7%,高出上坡位的25.4%。下坡位林分的单位面积木材蓄积量要远远高于中坡位和上坡位的,下坡位林分的单位面积木材蓄积量分别高出上坡位的75.1%,中坡位的44.8%。     

桂西南马尾松人工林生长对不同强度采伐的动态响应

[目的]研究不同强度采伐下马尾松的生长动态,筛选适宜的采伐强度,为马尾松人工林近自然经营提供技术支撑。[方法]2007年10月在14年生马尾松人工林(保存密度1 100株·hm~(-2))内进行采伐试验,设置4个采伐强度,即保留密度分别为225、300、375、450株·hm~(-2),以不采伐为对照;其后,自2008年开始连续8 a,每2 a测定1次马尾松的胸径、树高、枝下高和冠面积等生长指标,并计算单株材积和林分蓄积量,应用方差分析和Duncan多重比较分析生长指标对不同采伐强度的动态响应。[结果]表明:采伐强度显著影响林分生长,其中,林分平均胸径、单株材积、冠面积的年均增长量随保留密度增大而减小,但均显著高于对照(P0.05)。采伐后第1 3年,马尾松冠面积增长量显著高于采伐后期,胸径则在采伐后第3 5年最高,而不同采伐强度对林分树高生长影响不明显。保留密度显著影响林分枝下高和蓄积量的动态变化,其年均增长量随密度增大而递增。5个处理间林分蓄积年均增长量的差异随林龄的增大而逐渐缩小。[结论]马尾松人工林生长对不同强度采伐的动态响应以树冠最敏感,冠面积首先陡然增大,进而引起胸径的快速生长。树高和枝下高在采伐后年均增量变化相对平稳。4个采伐强度均显著促进单株材积生长,而仅保留密度为225株·hm~(-2)的采伐对林分蓄积增长量影响显著。综合比较林分的单株材积和林分蓄积连年增长量,建议在桂西南15年生马尾松人工林近自然经营中宜选择300株·hm~(-2)的保留密度进行采伐。     

Canopy openings may prevent fir broom rust (<Emphasis Type="Italic">Melampsorella caryophyllacearum</Emphasis>) infections

Melampsorella caryophyllacearum is a heteroecious fungus that produces disease on silver fir resulting in galls that depreciate the value of trees. Currently, little is known about its epidemiology. The purpose of this study was to identify those site or management factors associated with fir broom rust infection. A 29-plot systematic sampling was carried out throughout all silver fir forests in the Spanish Pyrenees. In every sampling plot, we examined each tree for the presence of M. caryophyllacearum galls or witch’s brooms. We differentiated their position as either on the main stem or on the branches of trees. We identified the most susceptible stands by relating a compendium of tree and stand variables with the presence and severity of symptoms. Disease symptoms were observed in 11.8% (95% CI: 5.8–17.9%) of trees. Fir broom rust-infected trees tended to be those of larger diameters. The rust infection was observed in 55.2% (95% CI: 35.7–73.6%) of the stands. We identified a wide range of severities with 5 of 29 stands having more than 30% of trees infected. Fir broom rust appeared to be a widespread disease, although we observed important differences in terms of severity. The presence and severity of the rust in stands was associated with understories composed of more shade tolerant plant species and with longer periods without thinnings. Canopy opening should be experimentally tested as a possible control method.