共查询到20条相似文献，搜索用时 31 毫秒
1.
Daniel G. Manson Susanne Schmidt Mila Bristow Peter D. Erskine Jerome K. Vanclay 《Agroforestry Systems》2013,87(1):233-250
Mixed species plantations using native trees are increasingly being considered for sustainable timber production. Successful application of mixed species forestry systems requires knowledge of the potential spatial interaction between species in order to minimise the chance of dominance and suppression and to maximise wood production. Here, we examined species performances across 52 experimental plots of tree mixtures established on cleared rainforest land to analyse relationships between the growth of component species and climate and soil conditions. We derived site index (SI) equations for ten priority species to evaluate performance and site preferences. Variation in SI of focus species demonstrated that there are strong species-specific responses to climate and soil variables. The best predictor of tree growth for rainforest species Elaeocarpus grandis and Flindersia brayleyana was soil type, as trees grew significantly better on well-draining than on poorly drained soil profiles. Both E. grandis and Eucalyptus pellita showed strong growth response to variation in mean rain days per month. Our study generates understanding of the relative performance of species in mixed species plantations in the Wet Tropics of Australia and improves our ability to predict species growth compatibilities at potential planting sites within the region. Given appropriate species selections and plantation design, mixed plantations of high-value native timber species are capable of sustaining relatively high productivity at a range of sites up to age 10 years, and may offer a feasible approach for large-scale reforestation. 相似文献
2.
人工林在保护香港自然环境起着重要作用,但绝大多数人工林为纯林,生态系统较为脆弱。人工林的改造对于增加林地生物多样性、提升人工林的生态服务功能具有重要意义。研究选取20 a 生的尾叶桉（Eucalyptus urophylla）林和马占相思（Acacia mangium）林进行间伐套种处理,套种密度为1665株／hm2;以不间伐林分为对照,比较间伐套种后林分的物种多样性及套种树种的生长表现。结果表明,间伐＋套种3 a后,与未间伐林分相比,尾叶桉间伐林分植物的科、属和种数分别增加了78．6％、116．7％和100％,马占相思间伐林分相反。DCA 分析结果显示,群落中灌木层和草本层物种主要聚集在尾叶桉间伐林分,马占相思未间伐林分物种数次之。与未间伐相比,间伐＋套种措施显著提高了尾叶桉林乔木层 Shannon-Wiener 指数和均匀度指数、灌木层的物种丰富度指数和均匀度指数及草本层的丰富度和 Shannon-Wiener 指数（P ＜0．05）;但马占相思间伐＋套种林分的乔木层、灌木层和草本层的 Shannon-Wiener 指数均显著低于未间伐林分（P ＜0．05）;物种多样性指标总体表现为尾叶桉间伐林＞未间伐林,马占相思未间伐林＞间伐林。套种树种在尾叶桉和马占相思林分中的早期生长表现良好,树种间生长量没有明显差异。 相似文献
3.
In a search for alternative methods for managing armillaria root disease in Pinus radiata plantations in New Zealand, a thinning trial was established in a 1985 planted stand infested by Armillaria novae‐zelandiae. The incidence of chronic (non‐lethal) infection rose significantly following a first thinning at age 7 years that provided additional inoculum in the form of colonized stumps. However, this effect diminished before age 19 years when the small stumps had decomposed and, contrary to expectations, a further increase in infection did not follow a second thinning at age 13.5 years, despite a high incidence of larger colonized second thinning stumps. Apparently the increased vigour and associated resistance in the released older trees was sufficient to counter any increase in inoculum potential following treatment. It therefore now appears that thinning may not be detrimental to the final crop volume in contemporary diseased second‐rotation plantations. However, this treatment furnishes no disease control benefit, and should still be deployed judiciously in heavily infested stands. There was a small, but significant reduction in volume growth on the more severely infected trees during the first 13 years in this trial, but on the larger trees later in the rotation at age 19 years there was no difference in stem volume between infection severity categories. A previous assessment based only on the earlier data therefore overestimates the impact of Armillaria in present and future pine plantations in New Zealand. Nevertheless, its widespread distribution and its demonstrated pathogenicity indicate that forest owners should be conscious of the presence of Armillaria during plantation management. 相似文献
4.
Martin Barrette Stéphane Tremblay Isabelle Auger 《Scandinavian Journal of Forest Research》2018,33(8):756-763
Commercial thinning enables forest managers to meet timber production objectives. Thinning reduces tree density to alleviate competition for resources and favour growth of selected tree species. However, in doing so, thinning can homogenize the composition of mixed-species forests and raise biodiversity issues. There is increasing evidence that species richness can lead to higher productivity through a complementarity effect. Hence, thinning that would maintain species diversity of mixed-species forests could enhance stand productivity and help forest managers to reconcile timber production objectives and biodiversity issues. The objective of this study was to compare post-thinning stand production, experimentally over 10 years, in mixed and monospecific stands of black spruce (Picea mariana [Mill.] B.S.P.) and jack pine (Pinus banksiana Lamb.). The post-thinning stand production curve of the mixed stand converged toward that of the unthinned mixed stand while the production curves of the thinned and unthinned monospecific stands remained parallel. The convergent productivity of the mixed stand could be explained by a positive interaction between effects of thinning and niche complementarity. We propose that thinning that maintains species diversity of mixed stands could help forest managers who are implementing ecosystem management to reconcile timber production objectives with biodiversity issues. 相似文献
5.
[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。 相似文献
6.
纸浆材人工林复合轮伐期的讨论 总被引：1，自引：0，他引：1
针对我国纸浆材人工林的经营现状和存在的问题,本文提出了复合轮伐期的概念。纸浆材人工林实行复合轮伐期经营的材积收获量,将比单一轮伐期经营高出20%,再加上复合轮伐期生产的大径锯材市场价格高的因素,相应的经济收益将高出更多。复合轮伐期充分利用了地力和林木生长的潜力,它不仅是纸浆材轮伐期和大径锯材轮伐期的复合,也是经营目的的复合,体现了现代林业多目标培育林木的经营原则。 相似文献
7.
Thinning of Korean pine (Pinus koraiensis Sieb. et Zucc.) is used to facilitate timber and cone production. The present study in Northeast China investigated the effects of thinning intensity on individual tree growth, temporal variation in cone yield, and seed quality in Korean pine plantation. In 2005, five thinning intensity levels (none, extreme, heavy, moderate and light) were set in 15 permanent plots in a 32-year-old Korean pine plantation at Mengjiagang Forest Farm, Jiamusi City, Heilongjiang Province. We recorded tree growth and seed cone production from 2013 to 2016, i.e., from 8 to 11 years after thinning. Except for height growth, thinning increased tree growth (diameter at breast height and crown size) and improved cone yield. The extreme thinning treatment (to 300 trees per hectare) resulted in the largest tree diameter, tree volume, crown size and 4-year cone production per tree. The highest cone yield per tree in the mast year (2014) was observed when stands were thinned to 500 trees per hectare (heavy thinning). Although the best cone and seed quality and the largest cone and seed mass per tree were recorded in the heavily thinned stand, no significant differences were found between heavy and moderate thinning stands (750 trees per hectare). At the stand level, the moderately thinned stand had the highest basal area, stock volume and seed cone production per stand. Our results suggest that thinning to 750 trees per hectare will improve timber and cone productivity in 40-year-old P. koraiensis stands. 相似文献
8.
We studied the effects of line thinning on stand structure, microclimate and understory species diversity of two Cryptomeria japonica D. Don plantations in south-central Japan. In each of two study sites we compared stand structure between the thinned stand
and an adjacent unthinned stand and found that line thinning increased the growth rate of residual trees such that stand basal
area may recover within 10 years after thinning. In the thinned stand, more open canopy conditions resulted in higher maximum
temperatures on the forest floor during the early growing season than in the unthinned stand. The thinned stand had greater
understory plant species richness and biomass than the unthinned stand. This study suggested that line thinning could potentially
enhance biodiversity while simultaneously increasing tree-growth rates in overstocked Cryptomeria japonica plantations. 相似文献
9.
Trang T. Tran Morag Glen Chris Beadle David Ratkowsky Caroline Mohammed 《Forest Pathology》2019,49(2)
Acacia hybrid (Acacia mangium × Acacia auriculiformis) clones are widely planted in Vietnam with a total of approximately 400,000 ha to meet the demand for pulpwood, sawn timber and wood chip exports. Silvicultural techniques such as pruning and thinning have been applied to improve productivity and sawlog quality of Acacia hybrid plantations. However, those techniques may also create opportunities for wood decay fungi to enter the Acacia hybrid stems through wounds and cause stem defects that reduce sawlog quality and the value of the plantation. The presence of fungal decay agents in Acacia hybrid trees was examined in two Vietnamese plantations. In July 2011, just prior to a second thinning, discoloured wood samples were taken from a three‐year‐old Acacia hybrid plantation at Phan Truong Hai for the isolation of fungi. In July 2012, approximately 18 months after pruning and thinning treatments, discoloured wood samples were taken from a three‐year‐old Acacia hybrid plantation at Nghia Trung for the isolation of fungi. DNA sequencing of the rDNA ITS identified the isolates. In May 2015, approximately 4 years after thinning and fertilizer treatments, discoloured and decayed wood samples were taken from the above (7‐year‐old) Acacia hybrid plantation at Phan Truong Hai for fungal identification. DNA was extracted directly from discoloured and decayed wood samples and fungal rDNA ITS amplicons sequenced on a Roche 454 sequencer. The results showed that silvicultural treatments did not affect the fungal communities associated with discoloured and decayed wood of Acacia hybrid plantation at Phan Truong Hai. A total of 135 fungal species or OTUs (operational taxonomic units) were identified, including 82 members of Ascomycota and 52 Basidiomycota. 相似文献
10.
Patterns of stand growth and dominance among individual trees change through stand development. We tested a prediction that large, old plantations of Eucalyptus saligna (Sm.) in Hawaii and Brazil would show a pattern of “reverse” growth dominance, with the largest trees contributing more to stand biomass than to current stand increment. This pattern might develop if the largest trees accounted for a large portion of the total resource use of the stand, but were less efficient at utilizing resources to produce stemwood. The 70-year-old plantation in Hawaii had a stem mass of 610 Mg/ha, compared with 325 Mg/ha in the 66-year-old Brazil plantation. Cumulative frequency plots for both sites showed that dominant trees comprised a very large proportion of total stand mass; the largest 20% of the trees accounted for 50% and 30% of the total stand mass in Hawaii and Brazil, respectively. Contrary to expectations, the largest trees continued to produce a disproportionately large amount of total stand growth, with the largest 20% of trees accounting for 60% (Hawaii) and 40% (Brazil) of stand growth. The frequency distributions resulted in positive growth dominance coefficients (similar to Gini coefficients) of 0.14 for Hawaii and 0.09 for Brazil, rather than negative values that would indicate that reverse growth dominance. The failure of these monoculture Eucalyptus stands to develop reverse growth dominance contrasts starkly with a variety of studies with pine species, which tend to show neutral-to-reverse growth dominance. Indeed, continued dominance of large trees suggests the trees might respond well to silvicultural treatments such as thinning or fertilization. Future work that contrasts patterns of growth dominance among species will be important as a foundation for developing generalizations about trends in growth dominance with stand development. 相似文献
11.
《Scandinavian Journal of Forest Research》2012,27(4):333-343
Abstract The initial density of a stand influences both the prethinning growth and the quality of the harvested trees. This study investigated the effects of different square spacings (2.0, 2.5 and 3.0 m) with thinning from above and thinning from below on stand development and tree characteristics in a 33-year-old Norway spruce [Picea abies (L.) Karst.] plantation in southern Sweden. Before thinning the total standing volume was not significantly different between treatments. Diameter at breast height (dbh) and diameter of the thickest branch were positively correlated. Before thinning, dbh of the trees and their thickest branches were significantly higher in the stands with 3.0 m spacing. After thinning, the dbh and the diameter of the thickest branch did not significantly differ between the 3.0 m spacing with thinning from above and 2.0 and 2.5 m spacing with thinning from below. Spacing did not significantly influence the presence or size of spike knots. The results suggest that a combination of wide spacing with thinning from above may yield timber of similar quality to denser spacing with thinning from below. 相似文献
12.
Worldwide, the land area devoted to timber plantations is expanding rapidly, especially in the tropics, where reptile diversity is high. The impacts of plantation forestry and its management on native species are poorly known, but are important, because plantation management goals often include protecting biodiversity. We examined the impact of pine (Pinus caribaea) plantations, and their management by fire, on the abundance and richness of reptiles, a significant proportion of the native biodiversity in tropical northern Australia, by (i) comparing abundance and diversity of reptiles among pine plantations (on land cleared specifically for plantation establishment), and two adjacent native forest types, eucalypt and Melaleuca woodlands, and (ii) comparing reptile abundance and richness in pine forest burnt one year prior to the study to remove understorey vegetation with pine forest burnt two years prior to the study. We also examined the influence of fire on reptile assemblages in native vegetation, by comparing eucalypt woodland burnt two years prior to the study and unburnt for eight years. To quantify mechanisms driving differences in reptile richness and abundance among forest types and management regimes, we measured forest structure, the temperatures used by reptiles (operative temperature) and solar radiation, at replicate sites in all forest types and management regimes. Compared to native forests, pine forests had taller trees, lower shrub cover in the understorey, more and deeper exotic litter (other than pine), and were cooler and shadier. Reptile assemblages in pine forests were as rich as those in native forests, but pine assemblages were composed mainly of species that typically use closed-canopy rainforest and prefer cooler, shadier habitats. Burning did not appear to influence the assemblage structure of reptiles in native forest, but burning under pine was associated with increased skink abundance and species richness. Burned pine was not warmer or sunnier than unburned pine, a common driver of reptile abundance, so the shift in lizard use after burning may have been driven by structural differences in understorey vegetation, especially amounts of non-native litter, which were reduced by burning. Thus, burning for management under pine increased the abundance and richness of lizard assemblages using pine. Pine plantations do not support the snake diversity common to sclerophyllous native forests, but pine may have the potential to complement rainforest lizard diversity if appropriately managed. 相似文献
13.
Korean pine is one of the most important plantation species in northeast China.Besides timber,it produces edible nuts and plantations sequester carbon dioxide from the atmosphere.This study optimized the management of Korean pine plantations for timber production,seed production,carbon sequestration and for the joint production of multiple benefits.As the first step,models were developed for stand dynamics and seed production.These models were used in a simulation–optimization system to find optimal timing and type of thinning treatments and optimal rotation lengths.It was found that three thinnings during the rotation period were optimal.When the amount or profitability of timber production is maximized,suitable rotation lengths are 65–70 years and wood production is 5.5–6.0 m~3 ha~(-1) a~(-1).The optimal thinning regime is thinning from above.In seed production,optimal rotation lengths are over 100 years.When carbon sequestration in living biomass is maximized,stands should not be clear-cut until trees start to die due to senescence.In the joint production of multiple benefits,the optimal rotation length is 86 years if all benefits(wood,economic profits,seed,carbon sequestration) are equally important.In this management schedule,mean annual wood production is 5.5 m~2 ha~(-1) and mean annual seed yield 141 kg ha~(-1).It was concluded that it is better to produce timber and seeds in the same stands rather than assign stands to either timber production or seed production. 相似文献
14.
Cheryl D. Nath Raphaël Pélissier B. R. Ramesh Claude Garcia 《Agroforestry Systems》2011,83(2):107-119
Traditional shade coffee plantations of Kodagu district, in the Western Ghats of southern India, harbor a high density and
diversity of trees. Local farmers appreciate native biodiversity, but plantation economics and public policies drive them
to gradually replace the original diversified cover with exotic shade trees such as Grevillea robusta, which grows fast and can be easily traded as timber. In order to identify and recommend native timber trees with fast growth rates, we compared the growth performance of four
common native species against that of G. robusta, by fitting steel dendrometer bands on 332 shade trees. Results showed that in general G. robusta had the fastest growth rates, but large trees of the native Acrocarpus fraxinifolius had faster growth in the wet western side of the district. Computer projections of long term performance showed that most
species were influenced by bioclimatic zone. Species-specific local environmental effects also occurred, including competition
from coffee bushes for A. fraxinifolius, influence of aspect for G. robusta, and management block effects for Lagerstroemia microcarpa. Our results show that native species potentially could produce timber at rates equivalent to those of exotic species. However,
as in many tropical countries, data on growth rates of native trees within mixed-cover plantations are scarce and this study
underlines the urgent need to screen for fast-growing species. Such information provides a strong basis for recommending appropriate
changes in public policies that would improve tree tenure security and encourage farmers to grow more native species. 相似文献
15.
通过对马尾松4~20年生不同密度的人工同龄纯林生长资料的分析表明:第1次树高生长分化高峰期在4~7年生,第2次在11~14年生,幼林郁闭后林木直径分化状态比较稳定。中幼林期抚育间伐主要采伐劣等木,进入近熟林期后除采伐劣等木外,还可采伐一部分中等木。间伐施工应以留优去劣为主,适当照顾均匀。总稀疏强度与密度呈正相关性,出现稀疏的时间随密度增大而提前;连年稀疏强度高峰期出现在林分郁闭后的一段时间内。根据总稀疏强度与稀疏时间同密度的关系可确定不同密度林分的间伐强度与时间。利用马尾松人工林观测资料拟合出与立地条件、现存株数密度、林龄三因子相关的自然稀疏模型,从而可推算出不同立地条件的自然稀疏表,为马尾松人工林密度调控提供科学依据。 相似文献
16.
《Scandinavian Journal of Forest Research》2012,27(4):289-303
Crown size is a good indicator of the growth potential of trees and is often used in forest management for outlining thinning guidelines or constructing forest growth models. The aim of this study was to analyse mean crown radius as a function of stem size, stand density and site productivity in even-aged stands of pedunculate oak (Quercus robur L.). Data included measurements of 620 trees from 53 plots in nine thinning experiments and one operational stand in Sweden, Denmark and Great Britain, representing a wide spectrum of thinning practices ranging from the strictly unthinned control to extremely heavy thinning with essentially solitary trees. Three sets of models were constructed based on different predictor variables, including indicators of individual stem size (diameter at breast height, DBH), stand density/thinning grade (quadratic mean diameter and stand basal area) and site productivity (stand top height). Preliminary results indicated a significant effect of DBH and (nominal) thinning grade on crown radius. The response pattern of the final models indicated an increasing crown radius with increasing DBH, with increasing thinning grade (decreasing stand density) and with decreasing site productivity. The models are valid for predicting the crown radius of pedunculate oak in even-aged forest stands. 相似文献
17.
M. Abdul Maleque Hiroaki T. Ishii Kaoru Maeto Shingo Taniguchi 《Journal of Forest Research》2007,12(1):14-23
We investigated the effects of line thinning on the abundance of Hymenoptera in two Japanese cedar plantations in northern
Hyogo Prefecture, central Japan, in order to evaluate the effectiveness of this silvicultural treatment for ecosystem management.
Line thinning is a silvicultural treatment practiced in Japan, where linear stand sections are cut (25%–35% of the total number
of trees) retaining one to two rows of trees. We used Malaise traps to capture Hymenoptera from the line-thinned stand (treatment
plot, including thinned and retained sections) and the unthinned stand (control plot). Overall, the total number of Hymenoptera
was greater in the treatment plot than in the control plot. The treatment plot hosted more functional groups and families
of Hymenoptera than the control plot in both plantations. In the Kuchiotani plantation (high-elevation site), the overall
abundance of Hymenoptera and of many Hymenopteran functional groups were positively correlated with both species richness
and biomass of understory plants. In the Sugi plantation (low-elevation site), understory vegetation was less developed and
there was no correlation with abundance of Hymenoptera. Our study indicates that line thinning is an effective silvicultural
treatment for future management of overstocked Japanese cedar plantations because it can fulfill biodiversity objectives,
but the effectiveness may depend on silvicultural and landscape factors. 相似文献
18.
19.
20.
Evaluation of native tree species for the rehabilitation of deforested areas in a Mexican cloud forest 总被引：3，自引：0，他引：3
Four native tree species (Liquidambar styraciflua, Juglans pyriformis, Podocarpus matudae, and Carpinus caroliniana) were evaluated for their suitability in rehabilitating degraded areas of Mexican cloud forest. Plant survival and growth in height and diameter were determined in three mixed-experimental plantations with different land use histories; their performance was compared with two on-farm plantations started by landowners for forest restoration. Nearby forest fragments were controls for soil compaction. An experimental plantation with remnant trees had the highest plant survival (82%), height, basal diameter and relative growth rate. The plantation with the steepest slope had high plant survival (63%) and growth. The plantation characterized by dominance of grasses and compacted soils had the lowest survival (22%) and growth. On-farm plantations had good establishment of planted trees (5–10 species planted), and facilitated the recruitment of 9–11 woody species. Carpinus and Liquidambar appear to be suitable species for reforestation in all these areas. Podocarpus grew relatively slowly, although it performed well in two experimental sites. Juglans had high survival (76%) under the stressful conditions of the most adverse site, and therefore may be useful for rehabilitation of degraded sites. Differences among species and sites strongly suggest that species success depends on plantation site quality. 相似文献