Journal of Forest Research Vol 15, No 1 (2010年2月)
■ SPECIAL FEATURE
Feasibility of silviculture for complex stand structures: designing stand structures for sustainability and multiple objectives
Title： Feasibility of silviculture for complex stand structures: designing stand structures for sustainability and multiple objectives
巻頁： J For Res 15 (1): 1-2
著者： 水永博己，長池卓男，吉田俊也，Sauli Valkonen
Title： Managing forest complexity through application of disturbance–recovery knowledge in development of silvicultural systems and ecological rehabilitation in natural forest systems in Africa
巻頁： J For Res 15 (1): 3-13
著者： Coert J. Geldenhuys
所属： Department of Forest and Wood Science, University of Stellenbosch, South Africa
抄録： How can we accommodate the diversity in tree species and sizes in mixed-species/size/age stands in the sustainable management of natural forests and woodlands in Africa for diverse timber and non-timber forest products and services, and during rehabilitation of degraded forests? The evergreen moist tropical to warm-temperate forests, from the equator to 34°S, generally function through relative shade tolerance. The tropical, strongly seasonal, drier deciduous woodlands generally function through adaptation to fire and/or grazing/browsing. Silvicultural systems, when implemented, are often not aligned with the ecological characteristics of the particular forest systems or the specific targeted species. This paper presents the concept of using the basic disturbance–recovery processes, with recovery development via stand development stages, as the basis for the development of silvicultural systems suitable for maintenance of forest complexity. Grain analysis and
stem diameter distributions, analysed from resource inventories, are used to determine the specific shade- or fire-tolerance characteristics of key economical and ecological tree species. The gained knowledge of the ecosystem and species characteristics (including modes of regeneration, i.e. from seed or vegetative regrowth) and processes is used to simulate the ecological disturbance–recovery processes through the development of mixed silvicultural systems, such as a single-tree selection system, a group felling system and a coppice management system in the same forest. Very similar concepts are used to develop rehabilitation strategies to recover the processes towards regrowth stands of diverse species and structure: through stands of introduced plantations and invader tree species; and through early regrowth stages in deciduous woodlands and evergreen forests, after fire, slash-and-burn traditional agriculture, charcoal production or open-cast mining.
Title： Silvicultural alternatives in an uneven-sized forest dominated by Picea abies
巻頁： J For Res 15 (1): 14-20
著者： Erkki Lähde, Olavi Laiho, C. Julian Lin
所属： Finnish Forest Research Institute, Finland
抄録： In this article, we report on the increments in basal area and tree diameter as well as the structural development observed in variously thinned plots that underwent either uneven- or even-sized treatment. The experimental forest was originally an uneven-sized mixed stand dominated by Picea abies. Twenty-eight randomized sample plots underwent each treatment, and the trees were monitored for 15 growing seasons after thinning. The uneven-sized plots retained a reverse J-shaped diameter distribution, but this was changed into a bell shape by low thinning in the even-sized plots. Absolute basal area increment was positively correlated with basal area in the even-sized treatment but not in the uneven-sized treatment. In the latter, all of the plots grew almost equally well, and only the basal area of broadleaves explained slightly positively the increment variation. Relative basal area increment was negatively correlated with basal area in both treatments. Additionally, the basal area of Scots pine was a positive explanatory variable in the relative increment variation in the even-sized treatment. For the dominant Norway spruce trees, diameter increment was negatively correlated with basal area in both treatments and, conversely, heavy removal increased the diameter increment. Relative basal area increment averaged 5% annually in uneven-sized plots representing the ‘‘target selection.’’ This was more than double the increment observed for the evensized plots that represented the ‘‘prevailing practice.’’ Likewise, the diameter increment of Norway spruce trees was 48% greater in the uneven-sized compared to the evensized plots.
Title： Patterns of tree growth in a single tree selection silver fir–European beech forest
巻頁： J For Res 15 (1): 21-30
著者： Matija Klopcic, Andrej Boncina
所属： Biotechnical Faculty, Department of Forestry and Renewable Forest Resources, University of Ljubljana, Slovenia
抄録： The basal area and height growth of trees and saplings in silver fir–European beech single stem selection forest were studied with regard to their social status and crown parameters of size, coverage, shading and vitality. On 24 permanent research plots (20 m × 20 m each) all trees [diameter at breast height (dbh) ≥10 cm] and saplings (≥1.3 m tall and dbh <10 cm) were surveyed. Repeated measurements of dbh (N = 1,608) and height (N = 1,135) 10 years apart enabled the calculation of annual basal area increment (BAI) of trees and saplings, and annual height (HI) increment of saplings. To obtain the growth characteristics for individual trees and saplings, their social status and crown parameters were assessed by rank. In the multivariate general linear model for BAI, social status, crown size and crown coverage of individuals as the predictors, and dbh2 as the covariate, explained 70% of total variability. Similarly, social status, crown size, crown coverage and crown shading had a significant impact on the HI of saplings, explaining 70% of total variability. Among the observed variables, social status determined according to the individual’s position in vertical stand structure was, in addition to dbh, the most important predictor for both BAI and HI. Significant differences were observed between the BAI and HI models for the main tree species (European beech and silver fir), indicating their different growth characteristics. The applied method could be used as a supplement to the more widely used approaches for studying basal area and height growth of individual trees in selection forest stands.
Title： Comparison of tree size structure and growth for partially harvested and even-aged hemlock-spruce stands in southeast Alaska
巻頁： J For Res 15 (1): 31-37
著者： Robert L. Deal, Troy Heithecker, Eric K. Zenner
所属： USDA Forest Service, PNW Research Station, USA
抄録： The effects of partial cutting on tree size structure and stand growth were evaluated in 52 plots in 13 stands in southeast Alaska that were partially harvested 53–96 years ago and compared with 50-year-old even-aged stands that developed after clearcutting. The net basal-area growth was greater in the partially cut plots than in the uncut plots, and basal-area growth generally increased with increasing cutting intensity. However, the basal-area growth of all of the partially harvested stands was significantly less than the growth of 50-year-old even-aged stands, and net basal area growth over the 50 year period since partial harvesting was about 33–43% of the growth of the even-aged stands. Partial cutting maintained stand structures similar to uncut old-growth stands, and the cutting had no significant effect on tree species composition. The tree size distribution of the partially harvested stands was far more complex and well distributed in comparison with the 50-year-old even-aged stands, and included the presence of several trees with diameters of more than 100 cm. These trees included both large-diameter spruce and hemlock trees and were a distinctive structural feature that was noticeably lacking in the even-aged stands.
Title： Can a natural experiment be used as a tool to design partial cutting regimes? The decline of Austrocedrus chilensis forests, an example
巻頁： J For Res 15 (1): 38-45
題名： 上層木の枯死後の更新状況を調べることは択伐林施業計画の立案に役立つか？Austrocedrus chilensis林の衰退を事例として
著者： Mariano M. Amoroso, Bruce C. Larson
所属： Department of Forest Resources Management, Faculty of Forestry, University of British Columbia, Canada
抄録： The forests of Austrocedrus chilensis in Argentina suffer mortality from what is locally known as ‘mal del cipre´s’. This disturbance usually appears as aggregations of dead trees of varying sizes. The mortality process seems unpredictable, and regeneration establishment is variable under these conditions. The highly variable mortality rates results in a natural experiment that allows the correlation of overstory mortality with regeneration rate. This correlation should then make it possible to estimate the regeneration success which would follow after different levels of partial cutting, allowing the purposeful direction of the regeneration process. We collected data from eight Austrocedrus chilensis-dominated stands and reconstructed overstory mortality over time and correlated it to the regeneration recruitment. Mortality showed two patterns: increasing ‘continuous’ mortality over time, and ‘pulses’ of important basal area loss in short periods. Overstory mortality had an effect on the recruitment and composition of the regeneration by allowing different species establishment depending on the degree of mortality. By quantifying mortality basal area and recruitment over time, we calculated estimates that can provide partial cutting guidance. Partial cuttings would then allow the purposeful direction of the regeneration process. Stand reconstruction studies provided a useful tool to help designing regeneration systems using a natural experiment. Some specific management implications for symptomatic A. chilensis forests are given.
Title： Evaluation of suitable conditions for natural regeneration of Picea jezoensis on fallen logs
巻頁： J For Res 15 (1): 46-54
抄録： 北海道の主要樹種であるエゾマツの蓄積は、更新に適した条件の少なさと過剰な収穫により、現在減少している。北海道における持続的な森林経営方法の開発のために、エゾマツの天然更新に適した立地を、4年間の天然林内での播種実験により評価した。倒木の環境条件（コケの群落高、倒木の硬さ、腐植層の了、光条件）を測定した。コケの高さは0 mm（Bark）、0-20 mm（Mthin）、> 20mm（Mthick）の3つにカテゴリー分けした。エゾマツの発芽率は、Mthinで最も高く、Barkで中間であり、Mthickが最も低かった。生残率はMthickで低く、BarkとMthinでは差が見られず、明るいほど高かった。成長は明るいほど良好であったが、根への分配率は環境条件の影響を受けていなかった。これらの結果から、明るい条件にあるコケがない、あるいは薄いコケがある倒木がエゾマツの更新に最も適していると決定した。我々は結果の一般性について、北海道で同所的に発生する種と他地域における結果との関連から議論した。
Title： Regeneration in windthrow areas in hemiboreal forests: the influence of microsite on the height growths of different tree species
巻頁： J For Res 15 (1): 55-64
著者： Floortje Vodde, Kalev Jõgiste, Loїc Gruson, Triin Ilisson, Kajar Köster, John A. Stanturf
所属： Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Estonia
抄録： Natural regeneration of windthrow areas is an important issue when planning forestry measures after forest disturbances. Seedling recruitment was investigated in storm-damaged hemiboreal mixed forests in eastern Estonia. The establishment and growth of seedlings from natural regeneration was registered for tree species in soil pits and in mounds of uprooted trees in stands that were either heavily or moderately damaged. Seedling growth is expected to be better in large but shallow soil pits created by uprooted Norway spruce [Picea abies (L.) Karst.] and poorer in small but deep pits created by the hardwoods in the area, silver birch (Betula pendula Roth.) and European aspen (Populus tremula L.). The most abundant regenerating species was birch. Pits hosted larger seedling numbers than mounds, due to soil instability in mounds. Rowan (Sorbus aucuparia L.) showed significantly faster growth than the other seedling species. Norway spruce pits were preferred to pits of other species by both birch and spruce seedlings. Black alder [Alnus glutinosa (L.) J. Gaertn.] did not show a preference for pits of a certain species of uprooted tree. Both spruce and rowan preferred hardwood mounds over spruce mounds. Storm severity also affected species composition: birch predominantly occurred on pits and mounds in heavily disturbed areas, while spruce was more abundant in the moderately damaged areas. The effects of advance regeneration and surrounding stands on seedling microsite preferences should be considered in future research and subsequent management recommendations.
Title： Effects of altitudinal gradient on species composition of naturally regenerated trees in Larix kaempferi plantations in central Japan
巻頁： J For Res 15 (1): 65-70
抄録： カラマツ人工林に天然更新した樹木の種組成に及ぼす標高傾度の影響を明らかにするために、山梨県櫛形山の標高1300-2000mにおける、カラマツ人工林59林分と天然林26林分で種組成を明らかにした。種組成は森林タイプ間で異なっており、特に高標高で顕著であった。また、天然林に有意に偏って出現する種は見られたものの、人工林に偏って出現する種は見られなかった。各調査区の立木密度と標高の有意な相関関係が、両森林タイプで同様である種 (オガラバナ、クリ、アオダモ) も見られたが、森林タイプによって相関関係が異なる種も見られた (例えば、イヌブナ、ミヤマザクラ、タカネザクラ) 。したがって、人工林管理は種の標高への反応を改変させており、それが種組成の違いをもたらしていた。このように、人工林に天然更新している樹種は管理によってすでに影響を受けていることから、人工林の生態的復元を計画・実行する際には標高傾度を考慮すべきであり、特に高標高では注意を要する。
Title： Feasibility of implementing thinning in even-aged Larix olgensis plantations to develop uneven-aged larch–broadleaved mixed forests
巻頁： J For Res 15 (1): 71-80
題名： 間伐作業による Larix olgensis の同齢人工林のカラマツと広葉樹の異齢混交林への誘導の可能性
著者： Jiaojun Zhu • Kai Yang • Qiaoling Yan • Zugen Liu • Lizhong Yu • Hexin Wang
所属： Institute of Applied Ecology, Chinese Academy of Sciences, China
抄録： Thinning experiments were conducted in larch (Larix olgensis) plantations to assess the feasibility of converting even-aged plantation stands to uneven-aged forests with more complex stand structures. Stands established in 1965 and 1960 were thinned in 2004 (Regime A, for determining the effect of recent thinning on emergence of seedlings) and 1994 (Regime B, for examining the effects of the past thinning on establishments of recruitments), respectively, at two intensities each. Natural regeneration, together with litter depth, canopy openness and vegetation cover, was surveyed in the thinned plots. Results indicated that larch seedlings started to emerge in May, reached a peak in June, decreased from June through September, and then disappeared in October. No larch seedlings exceeded 1 year old in the thinned plots because of the low levels of light and dense litter and vegetation cover. However, there were many naturally regenerated seedlings (5–50 cm in height) and saplings (50–500 cm in height) of broadleaved tree species such as Acer spp., Fraxinus spp., Cornus controversa, Quercus mongolica, and even the climax tree species, Pinus koraiensis, in the thinned plots. The mean density of regenerated seedlings reached 6.7 and 4.5 stems m-2 in Regimes A and B, respectively, whilst the mean density of regenerated saplings reached 4,595 stems ha-1 in Regime B. These results suggest that it is impractical to turn even-aged larch plantations to uneven-aged larch forests, but it may be feasible to develop uneven-aged larch-broadleaved forests from even-aged larch plantations through thinning.