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1.
燕山山地油松人工林林隙大小对更新的影响   总被引:3,自引:0,他引:3  
林隙(gap)又称林窗,指森林群落中老龄树木死亡或偶然因素(如干旱、台风、火灾等)造成成熟阶段的优势种死亡,从而形成林冠空隙的现象(Watt,1947)。美国生态学家Runkle(1982)将林隙分为2种,一种是林冠空隙(canopy gap),指上方无树冠遮荫的部分,即太阳处于正中位置时无树冠遮荫的面积之和;另一种是扩展林隙(expanded gap),指形成该林隙周围树木基部所包围的面积(Runkle,1981)。本研究所指的林隙为应用最为广泛的扩展林隙。近年来的森林动态学研究表明:林隙在森林结构和多样性维持中起着重要的作用,已  相似文献   

2.
调查太白山巴山冷杉-牛皮桦混交林林下与林隙乔木更新及土壤化学性质,分析林隙及土壤化学性质对乔木更新的影响.结果表明:巴山冷杉-牛皮桦混交林乔木更新苗密度较小,为0.059株·m-2,但林下与林隙均以巴山冷杉更新苗为主;林下与林隙乔木更新苗密度差异不显著(P=0.160),但巴山冷杉幼苗密度表现为林隙内显著高于林下(P =0.012);相关分析表明,小林隙更利于巴山冷杉更新(r=- 0.397,P=0.030),而林隙大小对牛皮桦更新没有显著影响(r=0.125,P=0.511);在林下,土壤碱解N、全P含量和pH值与牛皮桦更新苗密度呈显著正相关;在林隙内,土壤全P和有效P含量与巴山冷杉更新苗密度呈显著负相关,全P含量与牛皮桦幼树密度呈显著负相关;林下土壤有机质含量、全N含量和有效P含量及林隙土壤pH值、有机质含量、全N含量和碱解N含量与牛皮桦和巴山冷杉更新苗密度均没有显著相关关系;林下土壤pH值显著高于林隙,而有机质、全N、碱解N、全P和有效P含量显著低于林隙.  相似文献   

3.
本文调查了尼泊尔季节性干旱的娑罗双树原始林两种生态位(间隙和全郁闭)下树种多样性及苗木再生情况,并对物种多样性指标和苗木再生属性与林分间隙特征进行了相关性分析。结果表明,间隙生态位下乔木和灌木立木度高于全郁闭。间隙生态位下娑罗双树和榄仁树的幼苗密度也高于全郁闭,但是油榄仁和海南蒲桃的比较结果恰好相反。在幼苗层物种多样性指标(complement of Simpson index,Evenness index,and species-individual ratio)在间隙生态位要低于全郁闭条件。间隙大小能够解释物种丰富度和物种建立速率。多年多样伐木形成的林分间隙下娑罗双树幼苗密度要高于同一年内单一或多样伐木。结论:林分间隙的物种多样性通过增加幼苗密度来维持,并且适于娑罗双树再生。此外,林分间隙的其它属性也会影响物种多样性和苗木再生。  相似文献   

4.
本文调查了桉树人工林和邻近天然林内土著的木本植物多样性、密度和物种组成。桉树人工林和邻近天然林内分别圈画出20个20m×20m样地,记录下每块样地内的物种名称、物种丰富度、植株直径和高度以及采集亚样方(4m2)内幼苗数目。本试验中,记录人工林内木本植物46种,邻近天然林内52种,分别来自36个科。人工林内,物种多样性(H’)为2.19,林下木本植物密度为3842株/hm2,幼苗密度为4151株/hm2;而天然林内的物种多样性、林下树木密度和幼苗密度分别为2.74,4122株/hm2和8101株/hm2。两种林分的木本植物物种组成相似性较高。研究还表明,桉树人工林适合于Millitia ferruginia和小果咖啡生长和再生,而对下层木本则不适合。  相似文献   

5.
A review of the roles of forest canopy gaps   总被引:5,自引:0,他引:5  
Treefall gap, canopy opening caused by the death of one or more trees, is the dominant form of disturbance in many forest systems worldwide. Gaps play an important role in forest ecology helping to pre- serve bio- and pedo-diversity, influencing nutrient cycles, and maintain- ing the complex structure of the late-successional forests. Over the last 30 years, numerous reviews have been written describing gap dynamics. Here we synthesize current understanding on gap dynamics relating to tree regeneration with particular emphasis on gap characteristics consid- ered critical to develop ecologically sustainable forest management sys- tems and to conserve native biodiversity. Specifically, we addressed the question: how do gaps influence forest structure? From the literature re- viewed, the size of gaps induces important changes in factors such as light intensity, soil humidity and soil biological properties that influence tree species regeneration and differ in gaps of different sizes. Shade- tolerant species can colonize small gaps; shade-intolerant species need large gaps for successful regeneration. Additionally, gap dynamics differ between temperate, boreal, and tropical forests, showing the importance of climate differences in driving forest regeneration. This review summa- rizes information of use to forest managers who design cutting regimes that mimic natural disturbances and who must consider forest structure, forest climate, and the role of natural disturbance in their designs.  相似文献   

6.
雪灾干扰下林窗对木荷幼苗更新的影响   总被引:2,自引:1,他引:1       下载免费PDF全文
林窗干扰是维持森林生态系统的重要驱动力之一,对种子萌发、幼苗等自然更新过程、森林物种组成和动态、森林生物多样性的维持具有重要作用。本研究以2008年雪灾干扰后的浙江江郎山木荷林为研究对象,对木荷林窗大小结构、幼苗更新、生长等进行调查研究,结果表明:扩展林窗以50 100 m2的林窗个数最多(占总数的45.45%),各等级林窗中以50 100 m2的林窗占总面积比例最大(占总面积的30.31%)。林窗中木荷幼苗的平均高度和地径较对照林分分别高1.44 cm和0.61 mm,幼树在林窗中的平均高度和地径则比对照林分中分别高45.37 cm和5.00 mm且差异显著;林窗大小对木荷幼苗、幼树的高度和地径生长影响显著,中林窗中幼苗的高度和地径均高于小林窗和大林窗中的幼苗且差异均显著(F=4.893,P=0.007;F=5.203,P=0.004;n=357);幼树的地径在不同大小林窗中差异显著(F=3.569,P=0.037;n=43)。林窗幼苗的更新密度随着林窗面积的增大而增大,在林窗面积达到76 m2时,更新密度达到最大值,而后随着林窗面积的增大下降;中林窗和小林窗中更新苗木以低矮植株(1级、2级)为主,面积100 m2大林窗中,木荷幼苗生长较快。与他人研究的森林天然林窗相比,雪灾干扰后改变了林窗的大小分布结构和面积,50 100 m2的林窗比例较大,一定程度上更利于幼苗更新,具有相对较大的林窗幼苗更新密度;不论林窗大小,林窗内的更新幼苗都比林内多,郁闭度较大的林内或大面积的空地上都不利于更新幼苗的生长。因此,从受灾木荷林窗大小结构、幼苗更新、生长等来看,中林窗是幼苗适宜更新的面积,为木荷灾后恢复与重建提供了科学依据。  相似文献   

7.
Diversity, density and species composition of naturally regenerated woody plants under Eucalyptus grandis plantation and the adjacent natural forest were investigated and compared. Twenty plots, with an area of 20 m × 20 m for each, were established in both of E. grandis plantation and adjacent natural forest, independently. In each plot, species name, abundance, diameter and height were recorded. Numbers of seedling were collected in five sub-plots (4 m2) within each major plot. A total of 46 species in the plantation, and 52 species in the natural forest, which belongs to 36 families were recorded. The diversity of species (H′) is 2.19 in the plantation and 2.74 in the natural forest. The density of understory woody plant was 3842 stems/ha in the plantation and 4122 stems/ha in the natural forest. The densities of seedlings in the natural forest and the plantation were 8101 stems/ha and 4151 stems/ha, respectively. High similarity of woody species composition was found between the natural forest and the plantation. The E. grandis plantation was found favoring the regeneration and growth of Millitia ferruginia and Coffea arabica in a much better way than other underneath woody species.  相似文献   

8.
Diversity and regeneration of woody species were investigated in two ecological niches viz. gap and intact vegetation in old-growth seasonally dry Shorea robusta (Gaertn. f.) forests in Nepal. We also related varieties of diversity measures and regeneration attributes to gap characteristics. Stem density of tree and shrub components is higher in the gap than in the intact vegetation. Seedling densities of S. robusta and Terminalia alata (B. Heyne ex Roth.) are higher in the gap than in the intact vegetation, while contrary result is observed for T. bellirica (Gaertn. ex Roxb.) and Syzigium cumini (L. Skeels) in term of seedling density. The complement of Simpson index, Evenness index, and species-individual ratio in the seedling layer are lower in the gap than the intact vegetation. Gap size can explain species richness and species establishment rate. Gaps created by multiple tree falls in different years have higher seedling density of S. robusta than gaps created by single and/or multiple tree falls in the same year. In conclusion, gaps maintain species diversity by increasing seedling density, and favor regeneration of Sal forests. In addition to gap size, other gap attributes also affect species diversity and regeneration. Foundation Project: The study was supported by Swedish International Development Cooperation Agency (SIDA).  相似文献   

9.
We examined the response of understory plants in mature maple-dominated forests of southern Québec, Canada, following about 30 years of high deer densities, using a deer exclosure experiment. An exclosure and a paired control of 625 m2 each were established on six sites in 1998. An exclosure and a paired control of 16 m2 were added at each of the same sites in 2003 but under a recent canopy gap to determine if light could enhance plant responses. We measured plant richness and abundance, and aboveground biomass of different plant groups for 8 years in the understory plots and for 3 years in the canopy gaps. Four herbaceous species were also monitored individually in the same plots. No significant differences between treatments were found in plots under forest cover, except for lateral obstruction at 0–50 cm height which was higher in the exclosures. Under canopy gaps, however, tree seedling and total plant abundance were higher in deer exclosures than in control plots. Trillium erectum recovered partially as individuals were taller, had larger leaves and more frequently produced a flower or a fruit in the absence of deer browsing under forest cover. To a lesser extent, Erythronium americanum and Maianthemum canadense also exhibited signs of recovery but were still at the single-leaf stage after 8 years of recovery. In general, the different plant groups exhibited little recovery following deer exclusion, possibly because of the low light levels that prevailed in the understory of undisturbed maple-dominated forests. The higher latitude of the present study could also contribute to the slow recovery rates of the different groups of plants compared to studies conducted in northeastern USA. Variability among sites and years had an effect on detection of statistically significant differences. Trends are however appearing over time, suggesting that many understory plants are recovering very slowly following deer exclusion. Our results emphasize the importance of studying large herbivore–forest interactions on different groups of plants, but also on specific species, and under different latitudes to be fully understood.  相似文献   

10.
林隙微环境异质性及物种更新响应研究进展   总被引:2,自引:0,他引:2  
林隙作为森林循环和演替的重要场所,其内小环境特征随着时间和空间而改变,林隙内资源及其空间分布的不均匀性,为物种的共存和更新提供了环境条件,而物种分布的复杂性又进一步促进了森林小环境的异质性分化。本文从小气候状况、土壤及微地形方面对林隙小环境异质性问题进行了论述,并就林隙内微生境因子的异质性分布格局与物种拓殖策略的关系以及边缘效应对物种多样性形成和维持机制的作用等方面进行了阐述。  相似文献   

11.
Wolong Nature Reserve is the largest reserve for protecting the endangered wild giant panda. Due to historical factors, even in many sections of the core protection area, the forests have been seriously destroyed and natural forests are poorly restored. However, the relative importance of the determinants for recruitment of communities under disturbance is rarely explored. In our study the endogenous and exterior factors in a forest gap that affect the conifer-broad-leaved mixed forest regeneration were investigated near Wuyipeng, one of the observation stations at Wolong, to explore which determinant had the greatest effect on gap regeneration and to discover the recruitment of seedling establishment in forest gaps. With a linear sampling method, environmental factors, gap characteristics and recruitment of new individuals were measured and examined in every forest gap along three sampling lines. Data of environmental factors in the gaps were collected for a Pearson correlation analysis in order to explore the disturbance and preprocessed characteristics of the gaps, using principal component analysis in SPSS. Correlation analysis was applied to further explore the relationship between changes in the gaps and the response of the regenerating seedlings. The results show that a range of natural and human disturbances affected the pattern and characteristics of the forest gaps in this area. The richness in the composition of the seedlings was higher than that of gap makers, but the order of dominance of the composition was different between seedlings and gap makers. The success of dominant species in establishing themselves was affected by different environmental factors. For instance, the establishment of Betula spp. was correlated significantly with topographic factors, while that of Abies faxoniana was affected by soil characteristics and that of Rhododendron spp. correlated significantly with topographic factors and characteristics of gap makers. Moreover, all the biodiversity indices of regenerating seedlings were significantly correlated with environmental principle components mostly reflecting soil properties. From this we can infer that soil characteristics are the most important factors affecting the regeneration of dominant species and seedling diversity under gap disturbances. __________ Translated from Journal of Plant Ecology (Chinese Version), 2007, 31 (3): 425–430 [译自: 植物生态学报]  相似文献   

12.
Based on an investigation on gaps and non-gap stands of the Maolan National Karst Forest Nature Reserve, Guizhou Province, quantitative characteristics and dynamic changes of seed rain and seed banks in gaps were analyzed. The results show that the total amount of seed rain was 117.4 ± 32.6 seeds/m2 during the period of observation. The number of immature seeds was 56.3 ± 10.3 seeds/m2, that of mature damaged seeds was 15.7 ± 4.7 seeds/m2, and the number of mature germinated seeds was 45.4 ± 8.2 seeds/m2. It is suggested that the seed number is rich for gap regeneration. Seed rain in gaps has spatial and temporal heterogeneities which deeply affect regeneration patterns of gap plants. Along a gradient from the gap center to a non-gap stand, seed density in the litter layer, the number of species, and the Shannon-Wiener diversity index were gradually reduced, but these indices increased in the soil. The seed density in the gap center was 2415 ± 639 seeds/m2, near the gap center was 2218 ± 421 seeds/m2 and at the gap border area 1815 ± 311 seeds/m2. This shows that plants in gaps have good latent regeneration potential. In both gaps and non-gap stands, the Jaccard similarity index of seed in litter layer was the largest, second largest at 5–10 cm soil depth, and the least at the 0–5 cm soil layer the index. The Jaccard index between the soil seed bank and the present plant community was large in the litter layer, but decreased with soil depth both in gaps and non-gap stands. The results show that soil seed banks are the main source of gap regeneration in the karst forests of Maolan and contribute significantly to gap regeneration. __________ Translated from Acta Botanica Yunnanica, 2007, 29(3): 327–332 [译自: 云南植物研究]  相似文献   

13.
Tree seedling recruitment was monitored after various types of logging in mixed conifer and deciduous forests of northern British Columbia, Canada. Predicting tree seedling recruitment after disturbance is fundamental to understanding forest dynamics and succession and is vital for forest management purposes. Seedling recruitment success in multi-species northern latitude forests varied as a function of mature tree canopy cover, gap size and position in a gap. Recruitment was abundant within canopy gaps across a wide range of gap sizes (20–5000 m2), but recruit numbers dropped off rapidly under the closed forest canopy and in the open conditions of clearcuts. Inside canopy gaps, recruitment was similar by gap position in small gaps (<300 m2) but, in these northern latitude forests, exhibited a trend of increasing density from the sunny north to shady south end of larger gaps. This was true for all tree species regardless of their shade tolerance ranking. There was no evidence of gap partitioning by any of the tree species during the regeneration phase suggesting that adaptation to the subtleties of gap size during early recruitment are not well developed in these tree species. Favorable locations for emergence and early establishment of germinants were less favorable for growth and survival of established seedlings, i.e. the regeneration niches in these forests were discordant. Tree abundance and species diversity appears to be controlled more by differentiation among growth and survival niches than by the regeneration niches. From the perspective of forest management, abundant natural regeneration of all the dominant tree species of these mixed-species forests can be obtained after partial cutting.  相似文献   

14.
Canopy gaps play a significant role in maintaining structure and composition of tropical forests. This study was carried out in tropical evergreen forests of central Western Ghats in India to understand the influence of canopy gap size and the relationship of gap regime attributes to diversity measures and regeneration. The average gap size in the study area was found to be 396 m2 and around half of gaps were 4–8 years old. Gaps created by natural single tree fall were smaller in size but significantly higher in number. Diversity and regeneration of woody species were compared with canopy gaps and intact vegetation. Species richness and diversity was higher in gaps than in intact vegetation. Macaranga peltata, a shade intolerant species dominated gaps while intact vegetation was dominated by shade tolerant Kingiodendron pinnatum.Gap size significantly influenced species diversity and regeneration. Gap area and age were significantly and negatively correlated with diversity measures but positively correlated with regeneration. Among all the attributes of gaps, regeneration was significantly positively correlated with light intensity. Gaps maintained species diversity and favored regeneration of woody species. In addition to gap size and age, other gap ecological attributes also affected species diversity and regeneration.  相似文献   

15.
油松人工林不同大小林隙环境因子差异性比较   总被引:1,自引:0,他引:1  
【目的】油松Pinus tabulaeformis是我国北方地区主要造林树种。旨在阐明油松人工林抚育间伐24 a后形成的不同等级林隙间环境因子的差异,探讨林隙的形成对环境因子的影响以及环境因子间的相关关系。【方法】在油松人工纯林选择4种等级的林隙,即林隙直径和冠层平均树高(即林分平均高)之比分别为L-Ⅰ(0.75 H)、L-Ⅱ(1.00 H)和L-Ⅲ(1.25 H)(H为冠层均高)和对照(CK,林冠下),测量了生长旺季的环境因子(光合有效辐射、空气温度、空气湿度、土壤温度和土壤湿度),在此基础上,分析了不同林隙等级间和林隙内不同区域的环境因子的差异性以及环境因子间的相关关系。【结果】1)不同等级林隙间光合有效辐射和土壤温度均达到了显著差异(P <0.05),最大差值分别达到了167.94μmol/m^2s和0.7℃,且随着林隙面积的增大而增大。2)3个面积等级的不同区域间光合有效辐射均表现出了显著的差异,土壤温度仅在L-Ⅱ面积等级林隙中达到了显著差异(P <0.05),在林隙中心区域光合有效辐射和土壤温度具有最大值。3)除了L-Ⅲ面积林隙等级外,其余的林隙等级和对照内光合有效辐射与土壤温度之间均有显著的正相关性(P <0.05)。【结论】在油松人工林内,抚育间伐24 a后,间伐产生的不同等级林隙和林隙区域会对光合有效辐射与土壤温度产生显著影响,对其他环境因子的影响不大。  相似文献   

16.
Natural regeneration of Abies sachalinensis on soil was studied in a natural sub-boreal forest managed by single tree selection cutting located within the Hokkaido Tokyo University Forest. First, seedlings of A. sachalinensis on skid trails, soil mounds, soil pits, and undisturbed soil were counted, and their areas were measured. Most seedlings were found on skid trails. Seedling densities of A. sachalinensis on sites with soil disturbance, with the exception of soil pits, were significantly greater than that on undisturbed soil. Second, densities of Sasa senanensis, heights of S. senanensis, and seedling densities of A. sachalinensis on skid trails and undisturbed soil in both a closed-canopy stand and in a canopy gap were compared. Seedling density of A. sachalinensis on skid trails in the closed-canopy stand was significantly greater than that in the canopy gap. Average density and average height of S. senanensis, which is known to interfere with regeneration of many woody species, were significantly greater on skid trails and undisturbed soil in the canopy gap than those in the closed-canopy stand. It could be concluded from this study that both crown closure and soil disturbance are essential for natural regeneration of A. sachalinensis on soil in sub-boreal forests.  相似文献   

17.
The distance and direction coordinates from the center of each canopy gap to its edge in sixteen compass directions were measured in the secondary forests. Total of 21 gaps of different sizes were measured. The gap size was determined using different calculation methods: octagon method (OM), which was applied with two compass directions (OM_1 and OM_2); sixteen-gon method (SM); and elliptical-sector method (ESM), a new calculation method proposed in this work, including 8-elliptical-sector (8ESM) with two different compass directions (8ESM_1 and 8ESM_2) and 16 elliptical sector (16ESM). The results indicated that within the same gap delimitation, the average estimated gap size varied from 122.0 to 164.4 m2 with different calculation methods. The estimated area of the same gap among all calculation methods and between pairs exhibited significant differences (p < 0.05). Particularly, the estimated area for the same gap was significantly different between OM_1 and OM_2 (p < 0.005), indicating that the starting direction of the OM significantly affected the gap size. However, there were no significant differences among applications of the new method. When SM is used as a standard, the gap size calculated by OM was 10.0% less but, by ESM, was 11.6% larger. Therefore, the new method is proposed for future research involving the gap size calculation. Finally, we concluded that a comparison of forest gap sizes, particularly using OM, should be conducted when discussing the effects of gaps on forest regeneration and succession. Based on Chinese Journal of Ecology, 2007, 26(3): 455–460  相似文献   

18.
It remains unclear whether or not creating gaps in planted forests can increase the plant species composition, structure, and biodiversity, and also whether it can be helpful for restoring planted forests (to a more natural state). Based on a comparison of species composition and structure among forest patches, small gaps (4-25 m2), medium gaps (25-150 m2) and large gaps (150-450 m2), we found that (1) creating gaps enhanced vascular plant diversity. Both the species richness and Shannon diversity indices of small, medium and large gaps were significantly higher than in the understory. The pattern of increasing diversity of vascular plants with gap creation could be partly attributed to the emergence of novel shade intolerant species in gaps. (2) Creating gaps favored the colonization and regeneration of native species. Gap size influenced not only the emergence and density of individuals of different species, but also the emergence of different life form types. Small gaps promoted the regeneration of some shrub species, such as Ostryopsis davidiana, Rosa hugonis, and Forsythia suspense, leading to these species becoming canopy dominants early on in succession. The medium and large gaps favored the growth of tree species, such as Populus davidiana and Betula platyphylla (early successional stage), and Quercus liaotungensis and Pinus tabulaeformis (later successional phase). (3) The canonical correspondence analysis showed that plant species composition and distribution were mainly influenced by gap size and slope aspect, and that the recorded plant species could be divided into three life forms (trees, shrubs and herbs) on the biplot diagram. (4) Finally, creating gaps provided opportunities not only for native pioneer species in the early successional stage, but also for climatic climax species to grow to canopy dominants in later successional phases, suggesting that a more natural forest will develop with plant succession. Gap size plays an important role in plant regeneration, and it could be used to produce desired successional communities in near natural management for planted forests.  相似文献   

19.
《林业研究》2021,32(5)
The positive ecological interaction between gap formation and natural regeneration has been examined but little research has been carried out on the effects of gaps on natural regeneration in forests under different intensities of disturbance.This study evaluates the composition,diversity,regeneration density and abundance of natural regeneration of tree species in gaps in undisturbed,intermittently disturbed,and disturbed forest sites.Bia Tano Forest Reserve in Ghana was the study area and three gaps each were selected in the three forest site categories.Ten circular subsampling areas of 1 m2 were delineated at 2 m spacing along north,south,east,and west transects within individual gaps.Data on natural regeneration 350 cm height were gathered.The results show that the intensity of disturbance was disproportional to gap size.Species diversity differed significantly between undisturbed and disturbed sites and,also between intermittently disturbed and disturbed sites for Simpson's(1-D),Equitability(J),and Berger-Parker(B-P) indices.However,there was no significant difference among forest sites for Shannon diversity(H) and Margalef richness(MI) indices.Tree species composition on the sites differed.Regeneration density on the disturbed site was significantly higher than on the two other sites.Greater abundance and density of shade-dependent species on all sites identified them as opportunistic replacements of gap-dependent pioneers.Pioneer species giving way to shade tolerant species is a natural process,thus make them worst variant in gap regeneration.  相似文献   

20.
Studies of regeneration in African rain forests suggest that without silvicultural treatments, natural succession in logging gaps may not result in the establishment of timber species. In this paper we present the results of an experimental enrichment planting with moabi (Baillonella toxisperma Pierre), a valuable and important timber species harvested in Central Africa. Although forest gaps are generally considered as favourable for the regeneration of this species, a survey conducted in a forest concession in south-eastern Cameroon provided an estimate of only 12.7 seedlings ha−1, suggesting that the species was, in fact, poorly represented in logging gaps within the study area. To further investigate the dynamics of the moabi in logging gaps, 795 seeds were sown in 15 logging gaps and 410 nursery-raised seedlings were planted in 15 other gaps. A biannual monitoring program over a 30-month period showed a lower survival rate for seedlings from sowing (75.9%) compared to that of nursery-raised seedlings (95.3%). Planted seedlings reached an average of 229.3 cm tall whereas seedlings from sowing were 167.5 cm tall, with the observed difference roughly corresponding to the average height of the nursery-raised seedlings at the time they were introduced to the logging gaps. After 30 months, the diameters of planted seedlings (16.8 mm) were also greater than those of the directly sown individuals (12.5 mm). Forest gap characteristics significantly influenced the growth of the plants. Factors accounting for the differences were total solar radiation, the soil content of coarse sand, the topographic position of the gap, the vegetation cover and the density of Macaranga spp. Whilst total solar radiation had a positive influence on growth, the remaining factors had impacted growth negatively. A streamlined technique was tested by planting 7 seedlings in 250 gaps. Without additional site maintenance, 29.3% of the moabi seedlings emerged naturally from the competing vegetation after 24 months. With biannual maintenance some 89.4% of seedlings became successfully established. Clearance operations had no significant influence on the height of plants whilst plant diameter was greater in cleared gaps. The total cost of the enrichment technique was 5.5 EUR per gap without maintenance and 7.5 EUR per gap with a single maintenance measure. Whilst long-term monitoring is needed, this study suggests a high survival rate of moabi introduced in logging gaps, and a growth rate 10 times higher than previously reported under canopy cover. These findings, combined with the low costs of the enrichment technique, support the use of silvicultural measures in logging gaps to restore the forest.  相似文献   

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