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1.
Tomoaki Takahashi Kazukiyo Yamamoto Yosuke Miyachi Yoshimichi Senda Masashi Tsuzuku 《Journal of Forest Research》2006,11(2):117-123
Penetration rates of laser pulses transmitted from a small-footprint airborne light detection and ranging (LiDAR) system in
closed-canopy, middle-aged (40–50 years old) hinoki cypress (Chamaecyparis obtusa Sieb. et Zucc.) and sugi (Cryptomeria japonica D. Don) plantations that had similar levels of canopy openness were studied. The number of transmitted pulses was 107 427
points/ha for the hinoki cypress stand and 122 883 points/ha for the sugi stand. The penetration rates of the first (Pf) and second pulses (Ps) that reached the ground were 0.1% and 1.0% in the hinoki cypress stand, and 2.6% and 5.5% in the sugi stand, respectively.
Penetration rates for the total number of pulses (Pf+s) that reached the ground within each stand were 1.1% and 8.1%, respectively, and values for Pf+s, Pf, and Ps for sugi and hinoki cypress stands were significantly different (P < 0.001). The results of this study indicated that the generation of accurate digital terrain models in dense hinoki cypress
stands with complex topographies using only the data from laser pulses with poor laser penetration rates is likely to be difficult. 相似文献
2.
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. 相似文献
3.
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
4.
Satoshi Ito Satoshi Ishigami Yasushi Mitsuda G. Peter Buckley 《Journal of Forest Research》2006,11(4):243-251
We compared the occurrence of woody plants present in sugi (Cryptomeria japonica D. Don) plantations and evergreen broad-leaved natural forests in a warm-temperate region in order to characterize the understory
vegetation of sugi plantations. The influence of stand attributes on species occurrence in the plantations was evaluated using
logistic regression analysis. Out of 163 species, 65 plantation-preferring species and 31 natural forest-preferring species
were detected. The plantation-preferring species group contained deciduous species (38 of 65 species) that are characteristic
of coppice woodland, but all the natural forest-preferring species were evergreen plants. This indicates that the composition
of the woody understory in sugi plantations of the region is characterized by the species of open, disturbed habitats. Stand
age and the distance from the nearest natural forests were found to significantly affect the occurrence of evergreen shrubs
and plants with gravity-dispersed seeds, respectively, but the light environment of the stand had less effect. According to
the regression model analyses, long-term strategies such as lengthening the rotation (logging age) or creating patch mosaics
of plantations in the matrix of natural forests appeared to be effective in conserving woodland species that are characteristic
of evergreen, broad-leaved forests. On the other hand, increasing light penetration through thinning practices is a short-term
strategy that is less likely to be effective in promoting these species. 相似文献
5.
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
6.
[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
7.
Evaluation of carbon sequestration and thinning regimes within the optimization framework for forest stand management 总被引：2，自引：0，他引：2
Due to the urgent demand for thinning in planted forests and the tend towards sustainable forest resource management, the
forest stand age class eligible for the thinning subsidy in Japan was expanded during the period from 2000 to 2004. Currently,
further expansion is under consideration in line with meeting the Kyoto Protocol target of carbon sequestration. In this paper,
we conducted evaluation analyses of carbon sequestration and subsidy effects within the optimization framework for the forest
stand management. The optimal forest stand management model called Dynamic Programming model for Kyushu Stand Simulator (DP-KYSS)
was utilized for the analysis of the target sugi (Cryptomeria japonia) forest stand in the Kyushu region, Japan. Our results showed that the thinning subsidy was effective to stimulate thinning
activities at the eligible age class for the subsidy, and that 20% of the current or proposed payment was appropriate to give
an incentive to forest owners for conducting the same optimal thinning regime. The amount of carbon sequestered in remaining
trees at final harvest was not always shown to increase over time. Depending upon the subsidy condition, it could decrease.
The average annual amount of carbon sequestered under no subsidy showed its maximum at age 35, while under the other subsidy
conditions, it was shortened to age 25. The net present value of cost per unit carbon loss associated with subsidy became
the highest for the rotation age of 35 years for all subsidy policies considered here. 相似文献
8.
9.
The relationship of understorey herbage yield with light intensity and soil moisture content was investigated in a 20-year-old Pinus pinaster plantation in Kilkis of Macedonia, northern Greece, in three seasons (fall, winter and spring). The plantation was thinned at three density levels, high, medium and low (2500, 1750 and 1000 trees/ha respectively) and it was seeded with Dactylis glomerata. In addition, two fertilization levels (0 and 110 N+150 P2O5 kg/ha) and grazing intensity levels (0 and 0.8 sheep/ha/yr) were applied in a split-split plot experimental design. It was found that herbage yield was highest in the ungrazed and fertilized low tree density stands in all seasons. In the medium tree density stand, although light was lacking, fertilized plots produced higher herbage yield as compared to unfertilized low tree density stands while fertilization is of no use in close stands if herbage production is the goal. Animals seemed to prefer fertilized and medium density stands. Third degree polynomial equations were the best to explain herbage variation through the seasons both in fertilized and unfertilized plots. 相似文献
10.
Ferhat Kara 《Journal of Sustainable Forestry》2018,37(4):403-413
Stand density management tools help forest managers and landowners to more effectively allocate growing space so that specific silvicultural objectives can be met. Due to the economic importance of Oriental beech (Fagus orientalis Lipsky) forests in Turkey, a stand density management tool was developed for this species to optimize regeneration success rate and tree growth. For the development of this tool, named stand density management diagram (SDMD), we utilized forest inventory data from the Kastamonu Regional Forest Directorate in Turkey. Previously published forest management approaches and models were employed during the development of the tool. The SDMD illustrates the relation among four forest indexes: the basal area per hectare, number of trees per hectare, forest stand volume per hectare, and quadratic mean diameter of the beech stands. The stand stocking percent (SSP) can be determined based upon any two of these four measurements. The results suggest that SSP is a better predictor of tree growth than BA in Oriental beech forests. The newly developed SDMD allows for a more effective use of the growing space to achieve specific silvicultural objectives including tree regeneration, timber production, thinning planning, and wildlife protection in Oriental beech forests. 相似文献
11.
Jinghui Meng Yanfeng Bai Weisheng Zeng Wu Ma 《European Journal of Forest Research》2017,136(3):543-554
Coastal forests are normally established to mitigate coastal natural disasters instead of artificial barriers because of their low cost, ecological friendliness and economic benefits. The stand stability of coastal forests is of great importance to protect against coastal natural disasters. In the present study, we produced a stand density management diagram (SDMD) that can quantitatively guide the management of stand density to reduce the potential risk of windthrow in the coastal Casuarina equisetifolia L. plantations in southern China. The SDMD was developed using a relative spacing index (RS), average slenderness coefficient (SC) and a system of two equations as the basic components. The RS was used to characterize the growing stock, and the average SC was included to assess stand stability. Finally, we illustrated the application of the SDMD in formulating thinning schedules to secure stand stability. For comparison purposes, management options both with and without considering stand stability were produced and discussed. The study indicated that the SDMD produced here can provide detailed quantitative guidance of regulating stand density to secure stand stability for C. equisetifolia plantations. Additionally, this SDMD can be used to develop thinning schedules for a wide range of site qualities and management objectives for C. equisetifolia plantations. 相似文献
12.
Ashraful Alam Antti Kilpeläinen Seppo Kellomäki 《European Journal of Forest Research》2012,131(3):655-667
An ecosystem model (Sima) was utilised to investigate the impact of forest management (by changing both the initial stand
density and basal area thinning thresholds from current recommendations) on energy wood production (at energy wood thinning
and final felling) and management-related carbon dioxide (CO2) emissions for the energy wood production in Finnish boreal conditions (62°39′ N, 29°37′ E). The simultaneous effects of
energy wood, timber and C stocks in the forest ecosystem (live and dead biomass) were also assessed. The analyses were carried
out at stand level during a rotation period of 80 years for Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies L. Karst.) growing in different fertility sites. Generally, the results showed that decreased basal area thinning thresholds,
compared with current thinning, reduced energy wood (logging residues) and timber production, as well as carbon stocks in
the forest ecosystem. Conversely, increased thinning thresholds increased energy wood production (ca. 1–27%) at both energy
wood thinning and final felling and reduced CO2 emissions (ca. 2–6%) related to the production chain (e.g. management operations), depending on the thinning threshold levels,
initial stand density, species and site. Increased thinning thresholds also enhanced timber production and carbon stocks in
the forest ecosystem. Additionally, increased initial stand density enhanced energy wood production for energy wood thinning
for both species, but this reduced energy wood production at final felling for Scots pine and Norway spruce. This study concluded
that increases in both initial stand density and thinning thresholds, compared with the current level, could be useful in
energy wood, timber and carbon stocks enhancement, as well as reducing management-related CO2 emissions for energy wood production. Only 2.4–3.3% of input of the produced energy (energy wood) was required during the
whole production chain, depending on the management regime, species and sites. However, a comprehensive substitution analysis
of wood-based energy, in respect to environmental benefits, would also require the inclusion of CO2 emissions related to ecosystem processes (e.g. decomposition). 相似文献
13.
Sugi (Cryptomeria japonica D. Don) is one of the most important planted trees in Taiwan. The normal heartwood of sugi has a red to pinkish rose color. Unfortunately, this pleasant appearance is susceptible to discoloration after environmental exposures. This discoloration is a serious defect that decreases the value of sugi products. The objective of this study was to investigate the effects of environmental factors such as moisture, oxygen, and lights of different wavelengths on the discoloration of sugi. The results show that under the combined effects of light and oxygen the color of heartwood changes from red (or rosepink) to bluish green. The color further darkens and eventually turns to black with the presence of moisture. As for the effect of light wavelengths on the discoloration of sugi heartwood, it was found that the red color was enhanced after being irradiated with light of wavelengths above 600 nm. Botha
* andb
* values increased significantly as a result of such exposure. 相似文献
14.
Julia Dordel Suzanne W. Simard Jürgen Bauhus Brad Seely Luciano J. Pozas Cindy Prescott Hermann Hampel 《Forest Ecology and Management》2010,259(9):1846-1855
Toona ciliata (Australian red cedar), a valuable hardwood species, requires a nurse-tree overstorey to prevent damage from frost and drought in some regions of north-eastern Argentina. Different nurse-species offer different degrees of protection, resource competition, and thinning revenues. In addition, choice of nurse-species will influence trade-offs between T. ciliata establishment success, stem quality and productivity as well as revenue from intermediate and final harvests. We tested the effects of overstorey species and planting density on underplanted T. ciliata survival, stem morphology and growth. Initial stand densities of nurse-species Pinus taeda (625 stems/ha), P. elliottii × P. caribaea (625 stems/ha), and Grevillea robusta (833 stems/ha) were thinned by 0%, 25%, 50%, and 75% in three experiments, each using a randomized block design. Initial mortality, light availability and growth of T. ciliata, as well as growth of its nurse-trees, were measured before and two years after thinning. In the third year, we characterized T. ciliata stem morphology (straightness and height-to-diameter-ratio) and destructively harvested a subsample of T. ciliata in order to investigate T. ciliata biomass production and allocation patterns in response to overstorey species, thinning density and light availability. T. ciliata mortality was lower when planted under G. robusta than the pines, and increased in plots with greater exposure to solar radiation. T. ciliata productivity was also greater under G. robusta than under the pines, and was generally greatest where any of the nurse-species were thinned by 75%. Stem form was best when growing under P. taeda and in stands thinned by 50%, regardless of nurse-species. With the exception of early mortality, light levels appeared to have limited effects on T. ciliata growth dynamics. Neither growth rate nor stem morphology was strongly correlated with light availability. Total overstorey basal-area was highest in P. taeda stands and individual overstorey tree growth generally increased with decreasing stand densities, except for slower height growth of G. robusta in more open stands. Thinning operations resulted in sawn-wood revenue for the pine species only. Because stand productivity and stem quality were optimized under different nurse-species and thinning treatments, we conclude that the choice of nurse-species and thinning intensity will depend on management objectives and will change with market preferences and conditions. 相似文献
15.
The species richness of trees, shrubs and climbing plants was investigated in 41 sugi (Cryptomeria japonica D. Don) plantations of different stand age and area in southern Kyushu, southwestern Japan. Altogether 174 species were found,
of which 145 infrequent species were selected for analysis. Two groups were extracted from the species list according to their
occurrence in older (49 spp.) or younger (28 spp.) stands, the latter containing a higher percentage of climbing plants and
species with wind-dispersed seeds. In contrast, the older stand group contained major tree components typical of seminatural,
evergreen broadleaved forests in the region and was more heavily dependent on stand age, especially for species with gravity-
and frugivore-dispersed seeds, showing a gradual increase up to 60 years old. The species richness was less correlated with
edge perimeter facing seminatural forests and the years after latest thinning. The juxtaposition of plantation compartments
with stands of seminatural forest or other plantations, as well as the compartment's origin as former plantation site or a
seminatural stand, had relatively little influence on species richness. However, topographic variation was important in determining
the species composition, with valley stands having higher species richness and containing many plants typical of the regional
seminatural forests. These results suggest that (1) the major trend of species richness is determined by the presence of old
stand type species, (2) topographic variation of species richness remains even after establishment of plantations, and (3)
the normal rotation period of sugi plantations (35–40 years) may therefore be too short to conserve the maximum potential
species diversity within the working forest.
Received: June 4, 2001 / Accepted: August 26, 2002
Acknowledgments We wish to thank the staff of the Miyazaki University Forests for cooperation in the fieldwork. A part of this study was
supported by the Grant-in-Aid for Scientific Study from the Ministry of Education, Science and Culture of Japan (no. 09041071
and no. 10460068).
Correspondence to:S. Ito 相似文献
16.
The effects of various thinning and pruning methods on the density profile and annual ring characteristics of Taiwania (Taiwania cryptomerioides Hay.) using the drilling resistance technique were investigated. The results showed that thinning caused wider annual rings
than medium thinning or no thinning, and pruning caused narrower annual rings than no pruning. Moreover, the thinning treatment
affected annual rings more effectively than the pruning treatment. The average ring density after the thinning treatments
showed a trend as follows: no thinning > medium > heavy. This indicates that thinning reduces the average ring density. The
average ring density after the pruning treatments showed a trend as follows: medium > no pruning > heavy. However, the differences
between thinning and no thinning were not statistically significant. The percentage of latewood in Taiwania after these three
thinning and pruning treatments are shown. The results with silvicultural treatments have the order: medium > not treated
> heavy, but there are no statistically significant differences among thinning, pruning, and thinning where pruning interactions
were observed. Moreover, there were highly significant negative relations between the average ring width and the various ring
densities for Taiwania, but the determination coefficients were small. In addition, there was a highly positively significant
relation between the latewood percentage and latewood width.
Received: November 22, 2001 / Accepted: May 21, 2002
Acknowledgments The authors thank the National Science Council of ROC for financial support through grant NSC-90-2313-B-002-338, and the
Taiwan Forestry Research Institute for their contribution (210).
Correspondence to:C.-J. Lin 相似文献
17.
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
18.
Jack pine (Pinus banksiana) forests in parts of northern Lower Michigan have been managed with 30 years of extensive clearcut harvesting followed by planted stand establishment in order to maintain habitat for the endangered Kirtland's warbler (Dendroica kirtlandii). We used two, parallel chronosequences to study how this management has affected the structural development of jack pine stands relative to the historically dominant disturbance regime of stand-replacing wildfire. Each chronosequence consisted of three young stands (age range 3–6 years), three intermediate-aged stands (age range of 12–17 years) and three mature stands (age range of 39–69 years). Average stem density in young plantations (2300 stems/ha) was lower than the average for young, fire-origin stands (11,000) and varied over a much narrower range among stands (1403–2667 for plantations and 1552–24,192 in fire stands). In addition, within-stand patchiness of stem density was also much higher in the wildfire sites for young and intermediate ages. Plantation sites possessed very little dead wood at young ages (averaging 3 snags/ha and 12 m3/ha CWD) compared to young fire-origin stands (averaging 252 snags/ha and 49 m3/ha CWD). In contrast, mature plantations had similar levels of dead wood (averaging 269 snags/ha and 22 m3/ha CWD) as mature fire-origin stands (averaging 557 snags/ha and 12 m3/ha CWD). Differences between the plantation and fire-origin chronosequences were driven mainly by young- and intermediate-aged stands, whereas mature stands were typically quite similar in all structural features. Our results show clearly that forest management aimed at preserving and enhancing the population of a single endangered species results in greatly simplified habitat structure at the stand level, and suggest that this simplification is perpetuated across the landscape as well. Of particular concern are the effects of extensive harvesting and planting on the availability of snags and CWD. 相似文献
19.
Analyses of land snails and habitat factors in acid beech forests were conducted in southern Germany (northern Bavaria). The
objectives were to study the effects of habitat characteristics on snail density and species richness. Habitat structures
were determined for 37 plots in one big forest. We found a significant relationship between the number of snail species and
individuals and the following set of habitat factors coverage of herbaceous layer, growing stock, mean diameter at breast
height of the three largest trees (DBHmax), stand age, total dead wood volume per ha, and advanced decomposed dead wood volume
per ha. We use maximally selected rank statistics to estimate cutpoints separating stands with low densities, from stands
with high snail densities. Here, we define cutpoints for a significant higher snail density at a stand age of 187 years, 57 m3/ha dead wood, 40 m3/ha advanced decomposed dead wood, 63 cm DBHmax and more than 1% herbaceous layer. For species richness, cutpoints are estimated
at 338 m3/ha stand volume, 170 years stand age, 50 m3/ha total dead wood amount, 15 m3/ha advanced decomposed dead wood and 56 cm DBHmax. The microhabitat analysis shows a higher pH value and a higher Calcium
content at the bottom of large snags and under large lying dead wood pieces in comparison to litter, upper mineral soil and
at the bottom of vital living trees. Snail species and individual density are significantly linked to these patterns of chemical
parameters. The identified cutpoints are a good base for ecological management decisions in forest management. 相似文献
20.
Céline Leroy Sylvie Sabatier Novi Sari Wahyuni Jean-François Barczi Jean Dauzat Marilyne Laurans Daniel Auclair 《Agroforestry Systems》2009,77(1):37-47
In agroforestry systems, the distribution of light transmitted under tree canopies can be a limiting factor for the development
of intercrops. The light available for intercrops depends on the quantity of light intercepted by tree canopies and, consequently,
on the architecture of the tree species present. The influence of tree architecture on light transmission was analysed using
dynamic 3D architectural models. The architectural analysis of Acacia mangium and Tectona grandis was performed in Indonesian agroforestry systems with trees aged from 1 to 3 years. 3D virtual trees were then generated
with the AmapSim simulation software and 3D virtual experiments in which tree age, planting density, planting pattern and
pruning intensity varied were reconstructed in order to simulate light available for the crop. Canopy closure of trees was
more rapid in A. mangium than in T. grandis agroforestry systems; after 3 years the quantity of light available for A. mangium intercrops was three times lower than under T. grandis. Simulations with A. mangium showed that practices such as pruning and widening tree spacing enable to increase the total transmitted light within the
stand. On T. grandis, modification of the tree row azimuth resulted in changes in the spatial and seasonal distribution of light available for
the intercrops. These results are discussed in terms of agroforestry system management.
相似文献
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