共查询到19条相似文献,搜索用时 187 毫秒
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通过对山东省药乡林场日本落叶松间伐人工林进行标准地调查,揭示了日本落叶松间伐林的胸径,树高和材径生长变化特点,调查结果表明,初工1500~1800株/hm^2的日本落叶松人工林在本区首次间伐的开始期为林龄12-13年,首次间伐采用中,强度间伐效果最佳,第二次间伐的间隔期为5-6年,二次间伐宜采用间伐强度小的间伐。 相似文献
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根据日本落叶松人工林立木胸径生长规律和分化特征,确定了间伐起期和间隔期。利用林木冠幅与胸径生长的相关规律,计算出不同经级林分适宜的密度指标,作为确定间伐强度的依据。根据研究结果,在湖北亚高山丘陵区及其附近的相似地区,日本落叶松人工林7 ̄9a生时宜进行首次间伐,经4 ̄6a后再进行第2次间代。 相似文献
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日本落叶松人工林密度调控技术研究 总被引:1,自引:0,他引:1
以日本落叶松中幼林抚育间伐样地监测数据,利用树冠竞争因子(CCF)、林分密度指数、单位断面积生长过程等指标,分析了抚育间伐对断面积和蓄积两方面的影响,结果表明:间伐林分的断面积和蓄积有相同的生长过程,即林分在一定间伐强度范围内(强度小于50%)间伐强度越大,年均生长率越大;用树冠竞争因子描述日本落叶松人工林断面积的生长过程,未间伐林分的立木度接近稳定状态,而间伐林分降低了林分的CCF值,随着林龄的增加,CCF值不断增加,逐渐向未间伐林分靠近。总的来说间伐林分在间伐初期要小于未间伐林分,但随着林龄的增大及林木竞争的加剧,间伐林分逐渐向未间伐林分靠近。 相似文献
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《林业实用技术》2021,(6):89-91
根据林龄和已经采取的抚育间伐次数,选择日本落叶松(Larix kaempferi)中龄林小班2个,通过布设样地来调查树高、胸径、林木数量等林分因子,分析间伐次数与林分密度的关系以及对蓄积量和径阶的影响。随着间伐次数的增加,林分密度减小,同时林分的平均径、平均高和单株蓄积量增加,且随间伐次数的增多,增加量越大;其中单株蓄积量的变化最为明显,间伐增加1次可提高37.95%,增加2次可提高76.35%。基于抚育间伐而实施的密度控制技术,有效地促进了日本落叶松的生长、提高了单株蓄积量和林分中大径木的数量,是培育日本落叶松大径木林最为核心的技术措施之一。 相似文献
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日本落叶松人工林抚育间伐效果调查 总被引:3,自引:0,他引:3
在药乡林场日本落叶松人工林内设置固定标准地进行调查,结果表明:第1次间伐强度分别为12.2%、23.6%、34.2%,第2次间伐强度依次为23.0%、15.1%和10.4%。间伐能显著地促进林木生长,第1次间伐3年后林分蓄积量增长率比对照高5.8%~38.4%。第2次间伐2年后,不同间伐强度间林分生长差异不显著。认为:日本落叶松人工林初植密度可较大,第1次间伐宜采用中、强度间伐,第2次再采用较小强度的间伐。 相似文献
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通过计算叶面积大小,并结合林分的离散度大小和连年生长量的下降年限对日本落叶松人工林的抚育间伐时间进行了研究,结果表明,日本落叶松首次间伐时间确定11年左右为宜。 相似文献
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LIU Zu-gen ZHU Jiao-jun HU Li-le WANG He-xin MAO Zhi-hong LI Xiu-fen ZHANG Li-jun 《林业研究》2005,16(3):193-199
In order to understand the effects of thinning on microsite conditions and natural regeneration in the larch plantation, thinning experiment was conducted in a 40-year-old Larix olgensis plantation in Qingyuan County in eastern Liaoning Province, China in 2003-2004 Five thinning treatments (0%, 10.2%, 19.8%, 29.7% and 40.3% thinned) were designed on the same site. After thinning, canopy openness and the microsite conditions such as photosynthetic photon flux density (PPFD), soil moisture content, and soil temperature were measured in one growing season. Meanwhile, the investigation of natural regeneration was conducted at the end of the growing season. The results showed that the canopy openness increased with the increase of thinning intensities. PPFD and soil temperature and soil moisture content in different soil layers were positively relative with canopy openness after thinning. The richness of regenerating tree species did not significantly increase (p=0.30) after one growing season since thinning, but the regeneration density and frequency of tree species increased significantly (p〈0.05). In addition, the number of regenerating tree species increased, and the increment was correlated with the characteristics of iudividual tree species. The increasing percentage of regenerating seedlings of the shade-intolerant tree species was more than that of shade-tolerant tree species. Among the investigated regeneration species, the biggest response of seedling emergency to the canopy openness was Phellodendron amurense. This paper confirmed the following conclusions: after thinning, the variety of regenerating tree species was correlative with the characteristics of regenerating tree species, and the distribution of unthinned trees and the site conditions in the investigated larch plantation were the additional factors influencing, the regeneration. 相似文献
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Based on paper of “Theoretical derivation of risk-ratios for assessing wind damage in coastal forest“,wind damage in the pine coasteal forest,which was thinned at four levels in December of 1997,was investigated for four successive growing seasons.Besides wind damage,the wind profiles outside and inside the coastal forest stand and the distributions of optical stratification porosity (OSP) were also observed.Based on these data,risk-ratios of wind damage for both individual trees and stands were estimated according to the methods developed in “Theoretical derivation of risk-ratios for assessing wind damage in a coastal forest“.The results showed that risk-ratios of wind damage,which were calculated from the meen height and diameter only and from the combination of wind and stand sructure profiles,accurately predicted wind damage in the plantation.Relationships between different thinning ratios and incidence of wind damage showed that stand stability decreased soon after the thinning.This was due to the immediate effects of thinning on increasing the canopy roughness and wind load,and on decreasing the sheltering effects from surrounding trees.However,thinning strategies could improve the stability by long-term effects on growthand development of trees against extreme wind.Only canopy damage was recorded during the experimental period,no stem damage was found,even though the maximum 10-min wind speed outside the coastal forest attained 30.2m s^-1.The results obtained in this study indicate that thinning is the most effective silvicultural strategy available for managing coastal forest despite the increased probability of wind damage soon after thinning. 相似文献
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间伐对侧柏人工林生物量的影响 总被引:1,自引:0,他引:1
利用相对生长法研究了间伐对于徐州市石灰岩山地侧柏人工林总生物量、单株生物量和径级生物量的影响。结果表明:未间伐样地生物量总量为67.64t/hm^2,1次间伐提高了整个林分的生物量,总量提高到了70.11t/hm^2,2次间伐林分生物量反而明显减少,减少到了54.19t/hm^2;1次间伐(间伐强度27.7%)和2次间伐(间伐强度44.7%)都提高了树干生物量在林分总生物量中的比例,由53.12%提高到了58.68%和58.69%。1次间伐和2次间伐后,单株侧柏各器官及单株总生物量都比未间伐林地有显著增加,单株生物量由28.78k增加到41.24kg和41.68kg,树干生物量增长最为显著,由15.29k增加到24.20kg和24.46kg。未间伐样地,生物量集中在小径级的立木,间伐后生物量集中到了大径级立木。对照样地14cm和≥16cm径级的生物量所占比例分别为22.44%和6.57%,1次间伐之后,14cm和≥16cm径级的生物量所占比例增加到了26.44%和30.57%,2次间伐后,14cm和≥16cm径级的生物量所占比例达到了34.78%和28.94%。 相似文献
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Richy J. Harrod David W. Peterson Nicholas A. Povak Erich K. Dodson 《Forest Ecology and Management》2009
Forest thinning and prescribed fires are practices used by managers to address concerns over ecosystem degradation and severe wildland fire potential in dry forests. There is some debate, however, about treatment effectiveness in meeting management objectives as well as their ecological consequences. The purpose of this study was to assess changes to forest stand structure following thinning and prescribed fire treatments, alone and combined, in the eastern Cascade Mountains of Washington State. Treatments were applied to 12 management units, with each treatment combination replicated three times (including untreated controls). Thinning modified forest structure by reducing overall tree density by >60% and canopy bulk density by 50%, and increased canopy base height by ∼4 m, thereby reducing susceptibility to crown fire. The prescribed fire treatment, conversely, did not appreciably reduce tree density or canopy fuel loading, but was effective at increasing the density of standing dead trees, particularly when combined with thinning (37 snags/ha increase). Prescribed fire effects were more pronounced when used in combination with thinning. Thinning was more reliable for altering stand structure, but spring burning was lower in intensity and coverage than desired and may have led to results that downplay the efficacy of fire to meet forest restoration goals. 相似文献
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通过对落叶松人工林实施强度(39.7%)、中度(32.8%)、弱度(21.6%)的抚育间伐试验,结果表明:抚育间伐能改变落叶松人工林的土壤理化性质,中度间伐区有机质、全N含量比对照提高107%和83%,有效N、速效P、速效K的含量均为间伐区大于对照区,土壤容重、持水量、孔隙度也为间伐区大于对照区;不同间伐区土层(5~20 cm)温度高于对照区1%~7%。光照强度以中度间伐为适度。降雨量为对照区>弱度区>中度区>强度区。蒸发量为强度区>中度区>弱度区>对照区。树冠截留量为对照区>弱度区>中度区>强度区。 相似文献
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以辽宁冰砬山地区落叶松人工林、天然次生林综合流域森林为研究对象,采取林分、坡面径流场、集水区测流堰水文因子测定的方法,对综合小流域森林降水截留、坡面径流、区域径流输出等方面进行了研究。结果表明:辽宁冰砬山落叶松人工林和天然次生林冠层能有效的截留大气降水,其截留率分别为24.8%和16.6%;以Kostiakov方程对两种林地土壤入渗速率的模拟较好,模拟方程分别为iL=6.652t-0.179(R2=0.97)和iC=21.147t-0.162(R2=0.93);森林对大气降水的滞留时间随大气降水量和降水强度的增加而减少,但是小流域径流峰值出现的时间却是随着降水量的增加而延长,森林能够有效延缓和降低流域径流峰值出现的时间和高峰流量。 相似文献
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Pao-Shen Huang Hui-Chen Lin Chung-Ping Lin I-Min Tso 《European Journal of Forest Research》2014,133(5):919-930
Currently, information about the effect of forest management on biodiversity of subtropical plantation forests in Asia is quite limited. In this study, we compared the spider community structures and guild compositions of subtropical Cryptomeria japonica plantation forests receiving different degree of thinning (0, 25 and 50 %) in central Taiwan. The ground spider diversities and environmental variables were sampled/measured once every 3 months for 1 year before thinning and 2 years after thinning. Results showed that before thinning spider compositions did not differ significantly among three plantation forest types. Two years after thinning, spider species and family compositions of three plantation forest types differed significantly. In all three plantation forest types, the spider composition differed from year to year, indicating existence of temporal variations in spider diversity. Ground hunters (increased 200–600 % in thinned forests), sheet web weavers (increased 50–300 % in thinned forests) and space web weavers (decreased 30–50 % in thinned forests) were the major contributors of the observed spider composition differences among plantation forests receiving different treatments. The stands receiving thinning treatments also had higher illumination, litter decomposition rate, temperature and understory vegetation density. Thinning treatments might have changed the structures of understory vegetation and canopy cover and consequently resulted in abundance and diversity changes of these guilds. Moreover, the heterogeneity in understory vegetation recovery rate and temporal variation of spider composition might further generate spider diversity variations in subtropical forests receiving different degree of thinning. 相似文献