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1.
密度对肿节少穗竹生长影响的研究 总被引：6，自引：2，他引：4
本文通过对不同密度的肿节少穗竹的生长效应、生物量结构、竹冠结构和出笋量情况进行调查研究表明：密度在6万株／hm2的竹林具有最大出笋量、生物量、单株重量、胸径、竹高、冠幅和冠层厚;Ⅱ度竹对出笋量起着显著的影响,该密度有利于培育丰产优质的竹林。 相似文献
2.
通过对不同类型毛竹林植物物种多样性的研究,结果表明:毛竹林内物种是丰富的,但较大部分物种是脆弱的;乔木层植物物种多样性指数与林下木本植物物种多样性指数相关显著,与草本植物物种多样性指数相关不显著,乔木层物种多样性指数小于林下植物物种多样性指数;木本植物物种多样性指数,竹阔混交林＞竹针混交林＞毛竹纯林,粗放经营竹林＞中等集约经营竹林＞集约经营竹林;林下草本植物物种多样性指数,竹针混交林＞毛竹纯林＞竹阔混交林,中等集约经营竹林＞粗放经营竹林＞集约经营竹林;竹阔混交林向毛竹纯林转型时,林下木本植物部分丧失,而草本植物将可能增加,也可能减少. 相似文献
3.
毛竹密度效应新模型的研究 总被引：2，自引：0，他引：2
本文应用人工神经网络理论,对毛竹密度效应进行定量研究,建立了毛竹密度效应的三层前馈反向传播神经网络ＢＰ模型,仿真结果表明,人工神经网络模型能表征毛竹林分平均胸径、平均高度、密度对林分杆产量的映射效应,从而为毛竹密度效应研究提供了新方法。 相似文献
4.
We determine the relationships of culm surface area to other culm dimensions for one of the largest bamboo species, Phyllostachys pubescens Mazel ex Houzeau de Lehaie. A total number of 150 sample culms were collected from a stand of P. pubescens in Mt. Toshima, Kumamoto Prefecture, western Japan. The culm surface area for each sample was calculated, and then the relationships
of the culm surface area to basal area and product of diameter at breast height (dbh) and culm height were analyzed. The relationship
between culm surface area and basal area could be described successfully by the power equation, whereas there was a linear
relationship of culm surface area to product of dbh and height. Although the regression equations determined here would be
useful in estimating culm surface area of P. pubescens, it is necessary to select an appropriate equation depending on the purpose and available time and labor. 相似文献
5.
We investigated the effects of selective logging on stand structure and regeneration in selectively logged subboreal forests
in Taisetsuzan National Park in Hokkaido in northern Japan. The basal area decreased and the size structure of trees altered
in the stands studied due to repeated, intense selective logging, in which larger trees were cut down as a priority. Sapling
density in the stands was much lower than that in primary forests. In the simple and multiple regression analyses that were
used to estimate the effects of selective logging on sapling density, sapling density had a significant positive correlation
with tree density and had little correlation with the density of logged stumps or the height ofSasa (dwarf bamboo) growing on the forest floor. These results suggest that the establishment sites around canopy trees influenced
the establishment of saplings, rather than the gaps caused by selective logging. However, both the coefficient of determination
and the standardized partial regression coefficient of multiple regression analysis were higher for the stand with a dense
cover ofSasa than for the stand with a sparse cover ofSasa. Thus, the success of regenerating forests with selective logging depends on both the site of advanced regeneration and the
light conditions that regulate growth. 相似文献
6.
We assessed the relationship of the regeneration (seedling and sapling) densities of seven representative tall-tree species to the past partial cutting and current stand structure. We also determined if differences in tree regeneration were associated to establishment substrates (coarse woody debris (CWD) and root throws) and understory inhibitor vegetation (the dwarf bamboo species: Sasa senanensis). The study was conducted in 17 conifer–hardwood mixed stands in a heavy snowfall region in Hokkaido, northern Japan. The results suggest that stand structure, rather than logging intensity, is the primary factor influencing regeneration densities. Total conifer basal area was positively correlated with the regeneration density of individual tree species, including two conifers and three hardwoods. These patterns differ from those observed in old-growth stands in the region. A negative correlation between total conifer basal area and dwarf bamboo coverage suggests that the presence of dense conifer canopies causes an increase in regeneration density of tall-tree species by preventing domination of dwarf bamboo. Picea glehnii, a species that depends for its establishment strongly on CWD, has lower seedling and sapling density in stands with higher logging intensity. This seems to be a result of the decrease in the volume of CWD with increasing logging intensity in these stands. We suggest that both reducing logging intensity and retaining overstory conifers should be considered to develop a sustainable silvicultural system in this region. Providing sufficient CWD and root throws may also be important to ensure natural regeneration of tree species that require these as an establishment substrate. 相似文献
7.
对2种林分密度（低密度、高密度）、3种施肥处理（尿素、生物有机肥和钢渣肥）的毛竹胸径、新竹生长状况、相对增长产量进行研究,以确定钢渣肥能否替代复合肥和生物有机肥。结果表明：3种不同施肥处理间新竹株数、胸径以及产量均无明显差异;在不同密度条件下,新竹株数与产量同样没有产生明显差异,而对于平均胸径则为低密度林分明显高于高密度林分（P=0.041<0.05）。3种不同施肥处理并未对毛竹相对增产量产生显著差异（P=0.138>0.05）;在试验所设的2种密度中,低密度毛竹林相对增长产量显著高于高密度毛竹林（P=0.023<0.05）。基于钢渣肥较低的成本,在生产上可以用其取代尿素和生物有机肥,以提高竹林经营效益。 相似文献
8.
勃氏甜龙竹是一种优良的多用途竹种,近年来在许多适生区得到推广,其资源扩繁主要依赖于母竹移植。研究应用竹子生理整合性等生态学原理,以竹林林分结构调控为核心技术,采用不同林分结构组合,旨在探求笋苗兼用竹林经营模式。结果表明:(1)新造竹林有一明显的出笋数量和笋个体质量增长期,时间区段不同,前3a均快速增长,然后笋个体质量相对稳定,出笋数量仍较快增长。(2)竹笋产量主要影响因子是丛立竹数和立竹胸径,决定出笋数量和笋个体质量。出笋数量与丛立竹数正相关,与笋个体质量负相关。胸径与笋个体质量正相关,与出笋数量无相关。(3)合理的林分结构在450丛·hm-2时,丛立竹数为10株左右,胸径4～6cm。(4)经营类型经济效益明显,新造竹林第2年即有产出,第4年进入丰产期。 相似文献
9.
F. Lalnunmawia 《林业研究》2008,19(2):148-150
A study was conducted to investigate culms density and size, seed size and production rate in Melocanna baccifera stands disturbed by biotic pressure and fire. Results revealed that culms density, number and size of seeds produced in the bamboo stands were significantly affected by frequent fire and excessive biotic pressure （collection of young shoots for vegetables and mature culms）. The culm density and seed production rate decreased significantly in the stand subjected to excessive biotic pressure. An increasing exposure of culms to sun light was responsible for the above decrease. Seed production rate significantly increased in case of culms subjected to fire in comparison to the control. It indicated that fire stimulated the seed production in M. baccifera stand. 相似文献
10.
以内蒙古赤峰市阿鲁科尔沁旗沙日温都栎林自然保护区蒙古栎林为主要研究对象,研究不同林分密度对林下草本植物多样性的影响。结果表明,研究区内共有13科、14属、16种草本植物;Simpson指数、Shannon-Wiener指数、Pielou均匀度指数和物种丰富度指数均随着林分密度的增加呈先增大后减小的趋势,当林分密度为750株/hm2时,林下草本植物多样性指数达到最大值;林分密度与Shannon-Wiener多样性指数、Pielou均匀度指数、Simpson多样性指数、物种丰富度指数、树高、胸径均呈极显著负相关,与郁闭度呈极显著正相关,与枝下高不相关。综上所述,最合理的蒙古栎林密度为750株/hm2,该密度下最有利于蒙古栎林及林下草本植物生长发育。 相似文献
11.
Juan Carlos Camargo García Christoph Kleinn 《European Journal of Forest Research》2010,129(6):1213-1222
Three models for the prediction of bamboo culm length and two for culm volume were fitted from data of 303 guadua bamboo (Guadua angustifolia Kunth) culms. Data are from 101 temporary inventory plots systematically distributed over the coffee region of Colombia (inventory
area about 1,029,525 ha). Linear and non-linear regression models were used, and the precision of the models was evaluated
by cross-validation. The models were compared by studying the adjusted coefficient of determination, the bias, mean square
error and Akaike’s information criterion and by the F-test that compares predicted and observed values. For culm length, the best fit showed models that included predictor variables
related to stand characteristics such as quadratic mean diameter and number of culms per ha. For culm volume prediction, the
inclusion of culm length improved the model significantly. For the simple form factor model, precision of prediction was least.
The models developed are useful in facilitating the estimation of stand characteristics that are relevant for the silvicultural
management of Guadua stands and also for the assessment of their environmental services (such as carbon sequestration). 相似文献
12.
13.
Shuisong Zhang Changfa Chen Shouqing He Kexuan Wu Yousheng Zhan 《Frontiers of Forestry in China》2008,3(3):254-263
In the intermediate cutting intensity experiment of a Cunninghamia lanceolata plantation for 20 years, the changing pattern of natural thinning in these stands, with different intermediate cutting intensities,
was studied. The relationship between the number of trees removed by natural thinning and stand density and site conditions
was explained. The mathematical equation M = K
1·K
2 of natural thinning lines of C. lanceolata stand density management maps was tested and the relationship of diameter, height and canopy structure of stands with different
intermediate cutting intensities are proposed. Our study of natural thinning in these stands indicates that the starting and
peak periods of natural thinning in the check and slightly thinned plots were both early. The amount of thinned wood was large
and the course of thinning proceeded continuously. The three levels of thinning: the slight thinning period, the intensive
thinning period and the continued thinning period could be divided on the basis of the amount of thinned wood. Natural thinning
would be a very long process without artificial interference. The starting and peak periods of thinning in the middle and
strong intermediate felling are both late and present intermittence. Their thinning stages were not clearly evident. Through
our studies, we also discovered that stand density and site conditions had important effects on the number of dead and dying
trees, but that density was more important than site conditions. By way of tests, the relative error of the mathematical equation
of natural thinning lines of C. lanceolata stand density management maps was 3.91% and the precision was relatively high. The practical test results of the stands,
given different intermediate cutting intensities and different site indices, show that the relative error of the check plots
was 5.23%, while the relative errors of the other tested items were all < 5%, well within the allowable experimental error.
The mathematical equation was comparatively practical. The study demonstrated the distribution laws of diameter and height
classes of the stand at different intermediate cutting intensities. From this study we also obtained the growth differences
and changing dynamics of the height to the first branch, canopy length and relative canopy height of the stand at different
intermediate cutting intensities and various related patterns with an increase of stand age and proposed a mathematical model
relating stand age and the single-tree periodic volume increment.
__________
Translated from Scientia Silvae Sinicae, 2006, 42(1): 55–62 [[译自: 林业科学] 相似文献
14.
毛竹林凋落叶分解过程中土壤微生物学特性的研究 总被引：5，自引：0，他引：5
在两个试验点研究了３种林分立竹度和２种林分组成处理条件下毛竹林枯落叶分解的生化特性，结果表明，随分解过程，残留物及相邻表层土壤中的微生物数量和组成类群变化明显，并且受林分立竹度及组成等林分结构因子的影响较大，数量总体上表现为增加的趋势；组成上尽管细菌比例占绝对优势，但随分解过程有所下降，土壤酶活性行分解过程亦有显著变化，但各种酶活性的变化模式有所差异。与毛竹纯林相比，竹栎混交林的土壤酶活性较高。林地土壤酶活性与竹林立竹度相关，过氧化氢酶和脲酶在立竹处理２时较高，而蛋白酶和磷酸酶则在立竹处理１时较高。竹林土壤生化特性间及其与土壤养分含量、土壤温度、土壤含水量等因子相关联，磷酸酶活性为准优特征，土壤全氮含量为准优因子，脲酶是综合反映，竹林土壤生化性质的较好指标。 相似文献
15.
Yasumasa Hirata 《Journal of Forest Research》2008,13(3):147-154
This study aims to estimate stand density and stand volume in Cryptomeria japonica and Chamaecyparis obtusa stands from high-resolution satellite data and verify the reliability and uncertainty of the data. Sixty circular sample
plots of 0.04 ha each were established. Their stand densities were estimated from the number of tree crowns derived from high-resolution
satellite data using the watershed method. Stand densities derived from field surveys in the sample plots were compared with
those obtained from high-resolution satellite data by stand age class. As a result, there was a positive correlation between
them for sample plots of 41 years of age and over (R = 0.82); however, there was no correlation between them for sample plots of 40 years and under. Individual diameters at breast
height (DBH) were estimated from crown areas obtained from high-resolution satellite data for the two species. Using the estimated
DBH, individual tree heights were predicted from the height–diameter curves. Stand volumes were estimated from the sum of
individual volumes, which were derived from volume formulas having two variables, i.e., DBH and height. Stand volumes derived
from the field survey were compared with those obtained from high-resolution satellite data. The correlation coefficient between
them for stands of 41 years of age and over was 0.78. 相似文献
16.
We investigated decomposition and nutrient release patterns of leaf and sheath litter of two important highland bamboo species (viz. Phyllostachys bambusoides Sieb. (Zucc.) and Arundinaria racemosa Munro) by using a litter bag technique. Our objective was to improve understanding of the addition of organic matter and nutrients to soil from the litter of two abundant highland bamboo species, species that support the local population of the region in many ways. N concentration and N/P ratio were significantly higher (p<0.01) in leaf litter of P. bambusoides. Significantly, larger values of lignin concentration, C/N ratio, and lignin/N ratio were found in the sheath litter of A racemosa. Weight loss of both leaf and sheath litter was strongly positively correlated with N and N/P ratio, and significantly negatively correlated (p<0.01) with C/N ratio. Lignin/N had a negative correlation with decay rate. In both species, only lignin concentration of the litter showed strong positive correlation with N release. Litter decomposition and N release patterns were similar for the two bamboo species, whereas, P release rate from leaf litter was higher in P. bambusoides and differed significantly between sheath and leaf litter for both species. The complex pattern of nutrient release through mineralization and immobilization during litter decomposition ensures nutrient availability in both managed and natural bamboo stands subjected to anthropogenic disturbances. 相似文献
17.
Jean Carlos Budke Mariângela Santin AlbertiCleudes Zanardi Cintia BarattoElisabete Maria Zanin 《Forest Ecology and Management》2010
Bamboos’ vegetative growth are frequently associated to negative effects on tree recruitment and survival and despite this process, the effects of bamboo dieback after flowering events are poorly understood due the rarity of these events. 2 years after the massive flowering of the woody bamboo Merostachys multiramea in a southern South America subtropical forest, we compared changes in environmental conditions; tree species regeneration and production of new culms in canopy gaps resulted from bamboo dieback and areas of continuous canopy allowed by sparse bamboo cover. We observed sharp differences in environment conditions mainly resulted from differences in canopy openness and a NPMANOVA revealed differences among the stands regeneration directions (species composition and density). Average density, number of culms per sapling and total height of M. multiramea did not differ between stands, although slight differences were detected with increasing values toward opened sites. 相似文献
18.
[目的]基于华北石质山区侧柏人工林2014年(3—10月)降水数据进行量化分析,探究其降水的再分配规律。[方法]采用野外定位研究方法,对不同结构(郁闭度、枝下高)侧柏人工林林冠层降水再分配特征进行分析。[结果](1)1/2枝下高0.4、0.6、0.8郁闭度林内穿透雨总量分别为181.1、168.1、147.1 mm,穿透雨率分别为78.8%、73.1%、64.0%;树干径流总量分别为6.0、5.9、3.9 mm;总树干径流率分别为4.2%、2.6%、1.7%;林冠截留总量分别为39.5、56.1、79.1 mm;林冠截留率分别为17.2%、24.4%、34.4%。(2)1/3枝下高0.4、0.6、0.8郁闭度林内穿透雨总量分别为175.6、154.8、136.0 mm,穿透雨率分别为76.4%、67.3%和59.2%,树干径流总量分别为8.3、4.9、3.3 mm,总树干径流率分别为3.6%、2.1%和1.4%,林冠截留总量分别为46.3、70.4、90.7 mm,林冠截留率分别为20.1%、30.6%和39.5%。[结论](1)侧柏人工林同一枝下高不同郁闭度林分林内穿透雨量差异不显著。2种枝下高郁闭度为0.4和0.8之间的树干径流量均存在显著差异,郁闭度0.4和0.6以及0.6和0.8之间差异不显著。(2)郁闭度为0.4、0.6、0.8时,冠厚占树高2/3(即枝下高为1/3)的林分林冠截留量分别是1/2的1.17、1.25和1.14倍。(3)2种枝下高各自不同郁闭度间林冠截留量均存在显著差异。(4)同等降雨量情况下雨强越大,林冠截留量越小;2次降雨间隔时间越长,林冠层越干燥,林冠截留能力越强;枝下高越低(即冠层厚度越大),林冠截留量越大,且随着郁闭度的增加,林冠截留量逐渐增大。 相似文献
19.
The large-scale conversion of old forests to tree plantations has made it increasingly important to understand how understory vegetation responds to such landscape changes. For instance, in some forest types a reduction in understory richness and cover is thought to result from the development of canopy closure in plantations, although there is a paucity of empirical data demonstrating this relationship. We used a 420-year forest chronosequence as a case study to assess the relationship between stand age, tree canopy cover and understory vascular plant richness and composition in the Siskiyou Mountains of Oregon. The chronosequence consisted of six young managed (age 7–44) and nine older unmanaged (age 90–427) stands. All stands were similar in underlying geology, slope, elevation, and aspect. We found a non-linear relationship between stand age and richness, in which richness was highest in the youngest stands, reached a low in mid-aged stands (∼55 years), then increased in the oldest stands. We also found that percent tree canopy cover was correlated with total understory cover, richness, diversity, and species composition. In general, young stands were characterized by high shrub and graminoid cover and old stands were characterized by an abundant herb layer. Our work suggests that a major component of our study landscape is currently entering the forest stage (canopy closure) characterized by low levels of vascular plant species richness and cover. We use our results to discuss the potential effects of future forest management on understory plants. 相似文献
20.
林分密度对桉树幼龄能源林的影响 总被引：3，自引：0，他引：3
对0.5年生3种不同密度配置的幼龄尾巨桉优良无性系DH32-29各器官生物量、热值以及灰分进行了调查和测定,结果表明:所选3种密度间树高差异显著,基径差异达到极显著水平,随着密度的增加,树枝、叶片、树干的生物量分别呈现减少趋势,密度与树枝和树干生物量的相关性达到了0.01极显著水平;单株生物量随密度的增大而减小,林分生物量则相反;单株热值无显著差异,仅单株平均灰分含量高密度与中密度存在显著差异。综合分析,高密度0.25 m×2 m林分生物量最大,其灰分含量比低密度的林分低,适合作为能源林培育密度。 相似文献