不同间伐强度对水曲柳天然次生林生长动态及乔木层结构的影响

以水曲柳天然次生林为研究对象,以培育大径材为目标,采用典型取样法,研究不同强度间伐对水曲柳天然次生林的生长变化及乔木层组成结构的影响.结果表明:不同间伐强度对水曲柳胸径生长及材积生长差异显著,以弱度和强度间伐的天然次生林分中水曲柳中大径级林木较多,以中度间伐胸径生长率最大;不同间伐强度水曲柳天然林中,林木径级分布以强度...     

天然林择伐10年后凋落物现存量及其养分含量

以天然针阔混交林为研究对象,对4种不同强度(弱度、中度、强度、极强度)择伐10年后林地凋落物进行收集、取样和化学分析.结果表明:不同强度择伐作业10年后林地凋落物现存量和养分总量均下降,且下降幅度随采伐强度的增大而加大.强度择伐和极强度择伐10年后林地凋落物及其养分含量仍未恢复,但弱度择伐和中度择伐则与未采伐林地比较接近,说明弱度和中度择伐林地凋落物及养分含量在择伐10年后基本得到恢复.     

不同间伐抚育强度对华北落叶松人工林林下凋落物的影响研究

文章以塞罕坝地区华北落叶松人工林为研究对象,主要研究在不同间伐抚育强度下其林下凋落物的现存量和持水量的变化情况。试验选取立地条件和成林状况基本一致的林分进行研究,设置弱度、中度、强度3种不同程度的间伐抚育强度与未间伐抚育林分进行对比研究,研究结果发现:伐后林分凋落物现存量表现为未伐(6.747t/hm2)弱度(6.209t/hm2)中度(5.121t/hm2)强度(3.922t/hm2),各林分持水量表现为未伐弱度中度强度,依次是2.527t/hm2、2.218t/hm2、1.690t/hm2、1.251t/hm2,且均是半分解层大于未分解层,平均持水量与凋落物现存量表现趋势一致。     

辽东地区刺槐抚育间伐对林分生态环境的影响

通过对刺槐(Robinia pseudoacacia)抚育间伐固定标准地定点调查与分析,选取叶面积指数、平均胸径、草本植物多样性、间伐保留株数、透光系数、年凋落量、土壤容重、有机质含量作为综合评价森林生态效应的指标,进行关联度分析和主成分分析,研究抚育间伐对林地物理性质、化学性质、林内透光系数、林内温度的影响。结果表明:中度间伐强度对林地物理、化学性的改良效果最佳;随间伐强度的增加,林内透光系数和温度升高;凋落物、植物多样性和平均胸径是影响刺槐林间伐综合生态效果的主要因素。     

不同间伐强度蒙古栎次生林产流、产沙特征分析

【目的】以冀北山地蒙古栎天然次生林(35年生)为研究对象,探究不同间伐强度下植被因子对地表产流和土壤侵蚀的影响。【方法】设置5个间伐强度,采用径流小区法对不同间伐强度的地表径流、土壤侵蚀特征进行监测分析,利用灰色关联法对产流、产沙的影响因素进行关联度分析。【结果】1)2016和2017年各间伐强度产流特征均呈现:25%间伐强度 20%间伐强度 50%间伐强度对照 30%间伐强度 40%间伐强度,最大和最小产流差值在3.6 m~3/hm~2左右。2)2016年和2017年各间伐强度产沙特征略有不同,但都表现为50%间伐强度产沙量最大,与最小产沙量差值分别为6.38和3.11 kg/hm~2,20%间伐强度产沙量次之,25%、30%和40%间伐强度产沙量较少。3)灰色关联分析得出,除降水外,各影响因素对于产流影响大小依次为:郁闭度枯落物厚度林分密度冠幅灌草层盖度,对于产沙影响大小依次为:林分密度枯落物厚度冠幅郁闭度灌草层盖度。【结论】本区蒙古栎天然次生林水土保持效果较好,不同间伐强度土壤侵蚀模数变化范围为0.21～0.85 t/(hm~2·a),研究表明林分结构因子在本区蒙古栎天然次生林水源涵养中起主导作用,间伐抚育主要是通过林分结构的改变,改善林地水土保持的效果。     

不同间伐强度对蒙古栎次生林生长的影响

根据不同培育目标,对辽东山区蒙古栎(Quercus mongolica)次生林进行抚育间伐试验。结果表明:2013年蒙古栎林中度区林分平均胸径总生长量和平均生长率最大。抚育间伐对蒙古栎林蓄积生长作用明显,抚育间伐能提高蒙古栎林分蓄积总生长量、平均生长率和林分收获量,各指标随着间伐强度的增加先升高后降低,中度间伐效果最好。随着间伐强度的加大,蒙古栎林分小径木蓄积比例逐渐减少,中、大径材蓄积比例逐渐增大(弱度间伐除外);抚育间伐能有效的减少林木枯损量,改善林木的生长环境,促进林木的生长。中度间伐最有利于提高林分生产力,可培育小径材,既林分径阶为14cm,林木保留密度以972株/hm~2左右为宜。若想培育中、大径材,可加大间伐强度,极强度间伐效果最好,既林分径阶为18cm,林木保留密度以670株/hm~2左右为宜。     

不同间伐强度对辽东山区蒙古栎林生长的影响

通过对辽东山区蒙古栎林进行抚育间伐试验,结果表明：间伐17 a后,蒙古栎林中度区林分平均胸径生长率和林分蓄积量生长率最大;随着间伐强度加大,蒙古栎林分大径材比例逐渐增大（弱度区除外）;与对照区相比,各间伐区林分断面积生长率均有不同程度的提高。2012年中度区林分总收获量最大,弱度区次之。抚育间伐能有效地减少林木枯损量,改善林木的生长环境,促进林木的生长。综合考虑,中度间伐最有利于提高林分生产力,效果最好。     

抚育间伐对天然次生杂木林土壤理化性质的影响

采用标准地调查采样方法,研究不同强度抚育间伐对辽宁东部山区天然次生杂木林下土壤理化性质的影响。结果表明:弱、中度间伐区的土壤物理、化学性质各项指标优于对照和强度间伐区。说明适当的抚育间伐能提高天然次生杂木林土壤肥力。     

落叶松人工林抚育间伐生态效益分析

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。     

杉木人工林抚育间伐强度试验研究

为了研究间伐强度的规律性,试验采取弱度、中度、强度、极强度及对照等5种不同强度的间伐处理。试验表明,抚育间伐可以促进林木生长,提早成林,提高立木质量和获得短期的经济收入,但不能提高林分的收获量。以林分直径生长量与材积生长率以及其它有关因素来衡量,杉木抚育间伐应以强度间伐为依据。     

间伐对库区生态公益林养分流失的影响

以福建永安安砂库区生态公益林为研究对象,通过设置径流小区法,分别在坡度25°和32°的林地中,设计不间伐、间伐强度20%、40%、60%4种处理,研究不同间伐强度对安砂库区生态公益林养分流失的影响。结果表明:林地坡度25°情况下,在养分月流失量及流失总量上,间伐强度60%、40%均明显大于不间伐处理,而间伐强度20%与不间伐处理间差异并不明显,且流失量较少。林地坡度32°条件下,养分的月流失量及流失总量总体上随着间伐强度的加大而增加。此外,同一间伐强度下,养分流失总量随着坡度的增加而增加。可见,对库区生态公益林进行抚育间伐时,选择坡度较缓的林地进行低强度间伐(间伐强度20%)较为合理,能够在很好地发挥生态公益林的生态效益的同时获得一定的经济效益,进而实现库区生态公益林的可持续经营。     

Natural thinning and structural patterns of intermediate cutting intensity in a Cunninghamia lanceolata stand

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]     

不同抚育措施对杉木人工林生长量的影响

根据12块杉木人工中龄林标准地试验所得数据,运用方差分析及多重比较的方法,比较分析了施肥、抚育间伐、施肥 抚育间伐3种抚育措施对杉木生长量的影响.结果表明:施肥 抚育间伐对杉木人工中龄林的生长量影响最大,是杉木人工中龄林经营管理的较佳措施,从而为杉木人工中龄林的集约经营管理模式选择提供实践依据.     

间伐对侧柏人工林生物量的影响

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％。     

Assemblages of wood-inhabiting fungi related to silvicultural management intensity in beech forests in southern Germany

Current silvicultural treatments in beech forests are aimed at achieving thick logs without discoloured hardwood. Therefore intensive thinning is applied already in younger stands with the objective of large-sized trunks at an age of 100 years. However, this approach bears the risk that dead wood structures and broken trees are completely removed from the forest. The impact of three different silvicultural management intensity levels on wood-inhabiting fungi over decades was investigated in a large beech forest (>10,000 ha) in southern Germany in 69 sampling plots: A Intensive Thinning and Logging with high-value trees, B Conservation-Oriented Logging with integration of special structures such as dead wood and broken trees and C Strict Forest Reserves with no logging for 30 years. The analysis of community showed marked differences in the fungus species composition of the three treatments, independent of stand age. The relative frequencies of species between treatments were statistically different. Indicator species for naturalness were more abundant at sites with low silvicultural management intensity. Fomes fomentarius, the most common fungus in virgin forests and strict forest reserves, is almost missing in forests with high-management intensity. The species richness seemed to be lower where intensive thinning was applied (P = 0.051). Species characteristic for coarse woody debris were associated to low management intensity, whereas species with a significant preference for stumps became more frequent with increasing management intensity. A total amount of dead wood higher than 60 m³/ha was found to enable significantly higher numbers of species indicators of naturalness (P = 0.013). In conclusion, when applying intensive silvicultural treatment, the role of dead wood needs to be actively considered in order to maintain the natural biocoenosis of beech forests.     

New management options in chestnut coppices: an evaluation on ecological bases

The effects of long rotation periods and heavy low thinning on chestnut (Castanea sativa Mill.) coppices have been evaluated from a bio-ecological point of view. Aboveground tree biomass and its partitioning, bio-ecological indexes such as litter production, leaf area index (LAI), radiation regime, and growth efficiency have been analyzed for 4 years in thinned and unthinned permanent plots established in a coppice stand aged 11 years under normal rotation (NR) and in a coppice stand aged 35 years under long rotation (LR). A decrease in LAI, litter production and growth rate with the age was observed. LR showed high current annual increments (>16.0 m³ ha⁻¹ per year and 8.0 Mg ha⁻¹ per year for volume and aboveground biomass, respectively). Only slight differences in growth efficiency were observed. The adoption of heavy thinning (one third of basal area removal) affected stocking and determined significant differences in the light regime below the canopy, amount of gaps in canopy cover and LAI values, particularly in the years immediately after thinning, whereas slight differences were observed in growth efficiency. Nevertheless, chestnut showed a good aptitude, more evident in the younger stand, to re-build a homogeneous canopy cover: only a few years after thinning, canopy cover characteristics of thinned plots were similar to those of control plots and differences were not significant. Growth and increments in thinned plots were practically the same as in control plots, a consequence of consistently higher performances of released trees in the thinned plots. The results concur to a positive evaluation of a cultivation system based on long rotation periods and heavy thinnings, not only for the obtainable revenue, but especially from a bio-ecological point of view and make it a valid alternative either to abandonment or traditional over-exploitation of chestnut coppice stands.     

抚育间伐对栓皮栎人工林直径和树高分布的影响

[目的]以河南登封林场栓皮栎人工林为研究对象,研究抚育间伐对林分不同生长阶段林木株数、林木直径分布和树高分布的影响,为制定科学合理的抚育经营措施奠定理论和技术基础.[方法]在株数强度为31.55％的间伐林分和条件基本一致的未间伐林分内,分别设置1个1 hm2样地,间伐作业2 a后获取每木检尺数据,分别利用Normal分...     

Do thinnings influence biomass and soil carbon stocks in Mediterranean maritime pinewoods?

The effects of silvicultural treatments on carbon sequestration are poorly understood, particularly in areas like the Mediterranean where soil fertility is low and climatic conditions can be harsh. In order to improve our understanding of these effects, a long-term thinning experiment in a stand of Mediterranean maritime pine (Pinus pinaster Ait.) was studied to identify the effects of thinning on soil carbon (forest floor and mineral soil), above and belowground biomass and fine and coarse woody debris. The study site was a 59-year-old pinewood, where three thinnings of differing intensities were applied: unthinned (control), moderate thinning and heavy thinning. The three thinning interventions (for the managed plots) involved whole-tree harvesting. The results revealed no differences between the different thinning treatments as regards the total soil carbon pool (forest floor + mineral soil). However, differences were detected in the case of living aboveground biomass and total dead wood debris between unthinned and thinned plots; the former containing larger amounts of carbon. The total carbon present in the unthinned plots was 317 Mg ha^?1; in the moderately thinned plots, it was 256 Mg ha^?1 and in the case of heavily thinned plots, 234 Mg ha^?1. Quantification of these carbon compartments can be used as an indicator of total carbon stocks under different forest management regimes and thus identify the most appropriate to mitigate the effects of global change. Our results indicated that thinning do not alter the total soil carbon content at medium term, suggesting the sustainability of these silvicultural treatments.     

Responses of decomposition rate, nutrient return, and composition of leaf litter to thinning intensities in a Pinus tabulaeformis plantation

It is important to study the effect of tree density on the substrate quality and decomposition rate of leaf litter in plantations. In 2002, an experiment of the effects of thinning intensities at four different levels (i.e., 0 (I), 35.7% (II), 49.2% (III), and 64.2% (IV)) on undergrowth were carried out in an 18-year-old Pinus tabulaeformis plantation at an initial density of 3130 trees/hm² in the middle of the hills of Yingpan, Yanqing County, Beijing. Three years later, the rates of decomposition, the amount of nutrients returned, and the characteristics of leaf litter were compared by a litter bag method. The results show that the annual loss of dry matter of leaf litter in plots I, II, III, and IV was 25.81%, 26.25%, 27.68%, and 25.96%, respectively. The turnover of leaf litter was 10.04, 9.84, 9.24, and 9.97 years, respectively. Therefore, it is feasible and convenient to evaluate the effect of thinning on the rate of decomposition. In the first two months, the N, P, K, and Mg nutrients were released quickly. During the entire observation period of 14 months, the return of both N and Mg nutrients in the four plots exhibited a release-accumulation type of cycle. The return of P and K indicated a trend of release-accumulation and a relative balance. However, the return of Ca was far different from that of the other nutrients in the four plots. The total nutrient return of the four elements N, P, K, and Mg in the plots was 10.806, 31.016, 31.798, and 39.365 g/kg, respectively. Specifically, the quality of leaf litter in plot I was the worst in that N and Ca accumulated only 2.567 and 0.767 g/kg, respectively. Thinning did decrease the ratios of lignin to N and C to N and accelerated the rate of decomposition of leaf litter. The content of crude ash in leaf litter was enhanced by thinning, which prevented acid material, such as tannins and resins, from returning to the soil. The effect of thinning intensity was evaluated by the ratio of lignin to N, the ratio of C to N, and the ash content in leaf litter.     

Effects of selective thinning on growth and development of beech (Fagus sylvatica L.) forest stands in south-eastern Slovenia

We studied the effects of two types of selective thinning on beech stands formed by a shelterwood cut in 1910 — with lower number of crop trees and higher thinning intensity (T1) and higher number of crop trees with lower thinning intensity (T2). The stands were thinned in 1980, 1991 and 2001. Despite a lower stand density after thinning, the annual basal area increments of thinned stands in both thinning periods (1980–1991 and 1991–2002) were around 20% higher compared to those of the control (unthinned) stands. The mean annual basal area increment of dominant trees was 30–56% larger in the thinned plots compared to the control plots. Of 176 initial crop trees in the T1, 72% were chosen again during the last thinning. In the T2, 258 crop trees were chosen in the first thinning, and only 62% of these trees were chosen again during the last thinning. Only crown suppression and diameter classes of crop trees significantly influenced their basal area increment when diameter classes, crown size, crown suppression, and social status were tested. In the thinned stands, the dominant trees are more uniformly distributed if compared to the dominant trees in the control plots. Finally, the herbaceous cover and the species diversity were higher in the thinned plots.