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1.
Productivity of temperate broad-leaved forest stands differing in tree species diversity 总被引:1,自引:0,他引:1
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We investigated the individual-scale responses of five dominant species (Abies sachalinensis, Acer mono, Tilia japonica, Quercus crispula, and Betula ermanii) to single-tree selection harvesting in a conifer–broadleaved mixed forest in Hokkaido, northern Japan. Using data from stems
with a diameter at breast height of ≥12.5 cm, collected during 20 years of monitoring a 6.7-ha stand, we analyzed the effects
of harvesting in the neighborhood on tree recruitment and the growth (diameter class transition) and mortality of the residual
trees. The effects of harvesting varied considerably among tree sizes and species. Harvesting improved the recruitment of
A. mono and B. ermanii, and moderated the negative effect of the initial basal area of the surrounding canopy trees on the recruitment of Q. crispula. Conversely, harvesting limited the recruitment of A. sachalinensis by offsetting the positive effect of the initial basal area of the surrounding canopy trees. The growth of A. sachalinensis and Q. crispula decreased with the initial basal area of the surrounding canopy trees. Harvesting in the neighborhood resulted in an improvement
in the growth of the trees of these species only in the smaller size classes. With increasing local harvesting intensity,
the mortality of smaller A. sachalinensis trees decreased, whereas the mortality of larger trees increased. These results suggest that differences in the local harvesting
intensity, spatial patterns of harvesting, and initial stand structures influence the stand-scale dynamics in response to
partial harvesting in the mixed forests of this region. 相似文献
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Classifying tree species in a northern mixed forest using high-resolution IKONOS data 总被引:4,自引:0,他引:4
The high-spatial-resolution IKONOS satellite is now operating as a resource and disaster monitor, after a successful launch in September 1999. The ground resolution of the IKONOS panchromatic band is about 1m, the greatest of any satellite. The objectives of this study were to verify the extent to which high-resolution IKONOS data can be used to classify tree species. A field survey and image analysis study used IKONOS imagery to classify 21 species in mixed stands of deciduous and conifer species with the following results: (1) The panchromatic and multi-spectral bands 4, 3, and 2 were useful for classifying tree species owing to the great difference in the reflectance values between tree species. (2) Some groups, for which there were significant differences among species, were identified using Tukeys multiple comparison test; conifers and some broadleaved trees were identified correctly more often than other species. (3) A random selection of validation pixels showed that the overall classification accuracy was 62%. The classification accuracy of broadleaved trees was a little low, ranging from 40% to 63%, while that of conifers exceeded 70%. (4) The overall accuracy of the classification at the genus level improved by 4% more than the species level. The misclassification of broadleaved trees was due to the similar spectral characteristics of species in the same genus. 相似文献
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Point process models for mixed sessile forest stands 总被引:1,自引:0,他引:1
Marie Ange Ngo Bieng Christian Ginisty François Goreaud 《Annals of Forest Science》2011,68(2):267-274
• Background
Growth modelling of complex stands calls for the use of spatially explicit single-tree models. Such models require spatially explicit tree locations as the initial state to run simulations. Given the cost of such data, virtual forest stands, where tree locations are simulated, are generally used as the initial state. 相似文献7.
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Jos Ram n Ar valo Jos Marí a Fern ndez-Palacios 《Forest Ecology and Management》2000,130(1-3):177-185
We analyzed the germination from the seed bank for two laurel forest stands (Moquinal versus Aguirre) of Tenerife collected at two different seasons (summer versus winter). We incubated and monitored germination in greenhouse conditions for 1 year. A high variability in germination was found between trays. Germination was much higher in summer than in winter, especially from Moquinal seed bank. Shade tolerant species (Laurus azorica, Persea indica, Rhamnus glandulosa and Viburnum tinus) have a shorter germination delay than shade-intolerant species (Erica arborea, Erica scoparia and Myrica faya), which dominate the seed bank. The species composition of germinating seeds after one year did not reveal any differences between sites nor between, despite the high differences in number between seasons.
We compared the species composition of germinating seeds to that of the canopy (expressed as basal area). The results indicate that the winter seed bank does not significantly differ from the canopy composition in the Aguirre stand. We interpret our results to imply that the Aguirre stand is of an earlier successional stage than the Moquinal stand, because of a higher species richness in the germinated tree seeds, and compositional similarities between the winter seed bank and the canopy (both characteristic of earlier successional stages). 相似文献
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Identity of mycorrhizas and isolation of symbionts and associated fungi from Sitka spruce growing in pure and mixed stands with either Japanese larch or Lodgepole pine are described and compared. More mycorrhizal types and sporocarps of the Agaricales were collected from mixed stands. Mycorrhizas of Lactarius rufus, Paxillus involutus and Suillus spp. were more prevalent on roots from mixed stands. The most common unidentified mycorrhizal type (type B) had features similar to synthesized mycorrhizas of two Basidiomycete isolates. Suillus grevillei and three un-identified types were associated specifically with Japanese larch. The main associating fungi were Oidiodendron sp. and Mycelium radicis atrovirens. The association of a “nurse” tree with Sitka spruce provides a more diverse mycorrhizal flora, the majority of which are shared between the tree species. 相似文献
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Growing concern about increasing concentrations of greenhouse gases in the atmosphere, and resulting global climate change, has spurred a growing demand for renewable energy. In this study, we hypothesized that a nurse tree crop may provide additional early yields of biomass for fuel, while in the longterm leading to deciduous stands that are believed to better meet the demands for other ecosystem services. Ten different species combinations were planted, with two different stocking densities, at three different sites in Denmark. Significant differences, with regard to biomass production, were observed among the different sites (P?.001) and species combinations (P?.001) after 12–13 growing seasons. Compared to pure beech stands, mixtures with beech and Japanese larch on average produced 4.4?t ha?1?yr?1 more biomass. The additional biomass production was similar to what was obtained in stands with conifers only (Sitka spruce, Douglas-fir and Japanese larch), which produced 4.9–6.1?t ha?1yr?1 more biomass than the pure beech stands. No effects of initial planting density (P?=?.19), or of initial weeding (P?=?.81), on biomass production were observed. Biomass production of the broadleaved crop was in most cases reduced due to competition. However, provided timely thinning of nurse trees, the qualitative development of the trees will allow for long-term timber production. 相似文献
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Simple distribution models (SDMs) have deficiencies in portraying irregular forest diameter structure. This paper introduces mixture distribution models (MDMs) to improve the estimation accuracy of stand volume of Siberian larch (Larix sibirica Ledeb.) forests. Stand volume was estimated by combining the suitable diameter mixture model and diameter–height model. Appropriate mixture models are derived by integrating multiple SDMs of Burr III and XII, Johnson SB, Weibull or lognormal probability density functions (pdf) that satisfied the criteria of goodness of fit tests. Results showed that the average bias of volume estimation for all of the study plots using SDM and MDM approaches are underestimated by 6.93 and 2.42 m3, respectively. Each of the estimates is equivalent to an estimation error of 25.59 ± 18.18 and 7.08 ± 2.97 %. This suggests that the MDM approach is a more flexible and suitable modeling technique for forest volume estimation, in particular for forests that have been frequently disturbed by natural events. 相似文献
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采用目测判断、直接火烧、实验测定、火场植被调查和实地营造试验的方法,探究了防火树种的选择和防火林带营造技术。结果表明:防火树种的条件主要是枝叶茂密、含水量大、含油脂少、不易燃烧、耐火性强;下层林木应耐潮湿,与上层林木种间关系相适应;生长迅速、郁闭快、适应性强、萌芽力高;无病虫害寄生和传播。防火能力较强的树种有刺槐、核桃和青杨等;防火能力较弱的树种有三裂绣线菊、华北落叶松和丁香等。防火林带的营造技术条件是造林面积在100hm2以上,防火林带一般设置在山脊、林地边缘等,主林带宽度一般为30m左右,副林带宽度为20m左右,密度越大,防火效果越好。林带营造技术措施主要有整地、栽植和抚育管护。 相似文献
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在针阔混交林的不同林分中设置标准地,调查、研究树种的多样性及其组成。结果表明,在长白山系张广才岭支脉断块中山地貌条件下,当坡向一致、海拔高度相差不大时,不同针阔混交林林分中乔木树种多样性的差异不大,树种种类变动于19~21种之间;但不同林分的树种组成和优势树种有较大差别。这种状况预示着不同林分的演替方向会发生分化。 相似文献
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Frederick Gyasi Damptey Emmanuel Opuni-Frimpong Collins Ayine Nsor James Addai Daniel Kwame Debrah Benjamin Schnerch Felicity Bentsi-Enchill Henn Korjus 《林业研究》2023,(3):641-653
Tropical forests provide several ecosystem services and functions and support approximately two-thirds of the world’s biodiversity but are seriously threatened by deforestation.Approaches to counteract this menace have revolved around afforestation with several or a single tree species.We thus investigated how plantation forests with either a single or several tree species influenced arthropod taxonomic and community composition using pitfall traps to sample selected groups of epigeal arthropods... 相似文献
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One of the arguments against using prescribed fire to regenerate oak (Quercus spp.) forests is that the improvement in species composition of the hardwood regeneration pool is temporary and multiple burns are necessary to achieve and maintain oak dominance. To explore this concern, I re-inventoried a prescribed fire study conducted in the mid-1990s to determine the longevity of the effects of a single prescribed fire on hardwood regeneration. The initial study was conducted in three oak shelterwood stands in central Virginia, USA. In 1994, each stand was divided into four treatments (spring, summer, and winter burns and a control) and the hardwood regeneration was inventoried before the fires. During the burns, fire intensity was measured and categorized in each regeneration sampling plot. Second-year postfire data showed marked differences in species mortality rates, depending on season-of-burn and fire intensity: oak and hickory (Carya spp.) regeneration dominated areas burned by medium- to high-intensity fire during the spring and summer while yellow-poplar (Liriodendron tulipifera) and red maple (Acer rubrum) seedlings dominated unburned areas and all areas treated with low-intensity fire regardless of season-of-burn. The treatments were re-inventoried in 2006 and 2007 to determine whether these fire effects were still present. The new data show that the species distributions by season-of-burn and fire intensity found in 1996 still existed 11 years after the treatments. The fact that fire effects in oak shelterwood stands can last at least a decade has important management implications for resource professionals interested in sustaining oak forests in the eastern United States. 相似文献
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《Forest Ecology and Management》2004,199(1):1-10
We studied the effects of the regeneration cut of the shelterwood system and four site preparation options on populations of eastern red-backed salamanders in 90–100-year-old white pine forests in central Ontario, Canada. We established the study in 1994 using a randomized complete block design with three replicates and five treatments: (1) no harvest, no site preparation; (2) harvest, no site preparation; (3) harvest, mechanical site preparation; (4) harvest, chemical site preparation; (5) harvest, mechanical and chemical site preparation. We applied harvest and site preparation treatments from fall 1995 to fall 1997. We collected pre-treatment data in spring and summer of 1995 and post-treatment data from 1998 to 2002. We monitored salamander abundance using a grid of 20 cover boards surveyed 10 times per year within each of the 15 treatment plots. We also quantified changes in overstory and understory cover, supply of downed woody debris, and disturbance to the forest floor. Our data suggest that shelterwood cutting and site preparation can have immediate negative effects on the abundance of red-backed salamander populations in pine forest. However, effects are relatively short lived (<5 years). Changes in abundance appeared to be related to overstory and understory cover, and forest floor disturbance. 相似文献
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Marne A. Titchenell Roger A. Williams Stanley D. Gehrt 《Forest Ecology and Management》2011,262(6):980-988
Forest management practices, such as shelterwood harvesting, can greatly impact bat habitat relationships. Such practices can alter the amount of structural volume within a forest, which can influence bat foraging patterns. We determined the effects of shelterwood harvests of different retention levels (50% and 70% of full stocking) on bat activity patterns in oak-hickory forests located in southern Ohio. We used the Anabat system to monitor activity during May-September 2006. Our objectives were to quantify the effects of harvesting on structural volume and use the results to explain variations in bat activity. Because harvesting alters vertical structure as well as the total amount of volume within a forest, we also determined the height within the vertical profile where changes in structural volume begin to influence overall and species-specific activity. Overall bat activity did not differ significantly between shelterwood harvest levels, but was significantly different between harvested and control sites, with more passes detected within the harvested sites. Lasiurus borealis (red bat), Eptesicus fuscus (big brown bat), and Lasionycteris noctivagans (silver-haired bat) activity was significantly greater in harvested versus control sites, but did not differ between shelterwood harvest levels. Myotis spp. (Myotis lucifugus (little brown bat) and Myotis septentrionalis (northern Myotis)) and Perimyotis subflavus (tri-colored bat) activity did not vary between shelterwood harvest levels or between harvested and control sites. The greatest reductions in structural volume occurred in the understory to mid-canopy of the shelterwood harvests. Overall activity was most influenced by the amount of volume within 3-6 m above the forest floor, and declined as volume within that height strata increased. Mean bat passes declined by 50% when volume within 3-6 m exceeded 17 m3/ha. Estimated use by L. borealis decreased by 50% at volumes exceeding 1750 m3/ha in the understory to mid-canopy (0-12 m), while E. fuscus and L. noctivagans estimated use was the highest when volumes within 3-6 m were less than 63 m3/ha. Our results suggest that forest management practices that reduce the amount of structural volume in the understory to mid-canopy provide suitable habitat for foraging bats. Quantifying the amount of structural volume at various heights within the vertical profile of the forest can lend valuable insights into overall and species-specific bat activity patterns. 相似文献
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林木遗传工程及木质素的生物合成调节(英文) 总被引:1,自引:0,他引:1
林木遗传工程有利于保存林木遗传资源,改善全球气候,减轻自然林的过度采伐和满足人类日益增长的林木产品需求。控制林木真菌、病毒病、虫害和杂草的遗传工程方法正被广泛地研究和应用。尽管转基因林木的历史不长,种类不多,但它有广泛的应用前景。目前,抗除草剂基因、抗虫基因以及和木材质量相关的基因已被分离并应用于林木遗传工程。植物分子生物学和基因组学中的新技术使得高效林木遗传改良成为可能并将促进这些技术的商业化应用。木质素的应用已有一百年的历史,但木质素生物合成的全过程并不完全清楚。有关松树自然突变体和转基因林木的最新研究结果表明,木质素的生物合成是一个可以调节的过程。这些发现对完善木质素的生物合成途径、加深对木质素前体生物合成途径的理解和通过遗传工程改善木材质量有促进作用。本文综述了林木遗传工程在这些领域中取得的一些进展。 相似文献
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Changes in soil faunal assemblages during conversion from pure to mixed forest stands 总被引:1,自引:0,他引:1
Matthieu ChauvatDagmar Titsch Andrey S. ZaytsevVolkmar Wolters 《Forest Ecology and Management》2011,262(3):317-324
Replacement of native deciduous forests by coniferous stands was a common consequence of former European afforestation policies. However, these changes have proven to lead to serious ecological problems. Therefore, re-establishing mixed forests with native tree species became an increasingly popular management strategy to fulfil the demands of multi-functional forestry. We report about changes in collembolan assemblages and microbial performances during conversion of pure coniferous stands to mixed forests. The study was carried out in the Black forest area (SW of Germany), where a gradient of conversion from pure spruce stands (S1) to equally mixed stands (spruce, beech, and fir) at S4, through two intermediate stages (S2 and S3) was selected. Results clearly indicated strong modifications of the collembolan communities with an enrichment of the assemblages over the course of the conversion process. Mean species richness increased by 47% from S1 to S4 accompanied by diversity indices (Shannon and Simpson) higher at S4. Significantly different soil biota assemblages were found at each phase of the conversion process. Spatial turnover and nestedness contribute almost equally to the modification of assemblages from S1 to S2 while later on in the mixing process only spatial turnover was acting. Concomitantly, significant shifts in the functional structure of the collembolan assemblages were depicted, deep-dwelling collembolan (euedaphic) being, surprisingly, the most responsive group. In contrast, neither microbial nor coarse environmental parameters were influenced by the factor “conversion phase”. We suggest that stimulation of Collembolan communities after the mixing process was mainly due to the input of more suitable food sources and/or microhabitat increases. Our findings underline the crucial role of aboveground processes on the belowground system, with the intensity and scheme of the mixing-process as important factors to consider when aiming at soil biodiversity improvement in forest systems. 相似文献