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1.
《林业研究》2021,32(4)
Forest management may have significant effects on forest connectivity and natural population sizes.Harvesting old-growth single trees may also change natural patterns of genetic variation and spatial genetic structure.This study evaluated the impacts of forest management using a silvicultural system of seed trees on the genetic diversity and spatial genetic structure of Eremanthus erythropappus(DC.)MacLeish.A complete survey of 275 trees on four plots was undertaken out to compare the genetic variation of a managed stand with an unmanaged stand.We genotyped all adult and juvenile individuals 60 months after the management and compared the genetic diversity and the spatial genetic structure parameters.Genetic diversity was considered high because of an efficient gene flow between stands.There were no genetic differences between stands and no evidence of inbreeding.Genetic clustering identified a single population(K=1),indicating no genetic differentiation between managed and unmanaged stands.Adult and juvenile individuals of the unmanaged stand were more geographically structured than individuals from the managed one.There was a tendency of coancestry among juveniles at the first class of distance of the managed stand,suggesting a drift of genetic structure possibly caused by management.Understanding early responses to management on genetic diversity and stand structure is a first step to ensuring the effectiveness of conservation practices of tree species.The sustainability of forest management of E.erythropappus on genetic diversity,and more accurately,on spatial genetic structure needs evaluation over time to promote effective conservation of the population size and genetic variability. 相似文献
2.
The conversion of anthropogenic into more natural, self-regenerating forests is one of the major objectives of forestry throughout
Europe. In this study, we present investigations on permanent plots with different silvicultural treatment in NE German pine
stands. Management of old-growth pine stands on acidic and nutrient-poor sandy sites differs in fencing, thinning, and planting
of certain tree species. The investigations were carried out on the community, population, and individual level of the pine
forest ecosystems. Thus, vegetation changes, size and height of tree populations, and height increment of tree individuals
were observed over a time span of 6 years. Special attention was paid to short-lived tree species such as, e.g., Frangula alnus and Sorbus aucuparia, as well as to Fagus sylvatica as one of the most typical forest tree species of Central Europe. Vegetation changes are interpreted as a consequence of
natural regeneration of formerly degraded forest sites, involving an increase in nutrient availability. High browsing pressure
can be considered as a key factor for the inhibition of tree seedlings and growth of saplings. Some Sorbus aucuparia individuals, however, succeeded in growing out of the browsing height also in unfenced stands. Few found specimens of Fagus sylvatica proved that this species is able to establish spontaneously on these relatively dry, acidic sites under continental climate
influence. Such natural regeneration processes, also including spontaneous rejuvenation of trees, can be integrated into silviculture
as passive forest conversion management. An active management like thinning of stands, planting of trees, and fencing can
accelerate forest conversion with regard to height growth and species number of trees. 相似文献
3.
A. Dounavi N. Koutsias M. Ziehe H. H. Hattemer 《European Journal of Forest Research》2010,129(6):1191-1202
Analyses of distribution patterns and genetic structures of forest stands can address distinct family structures and provide
insights into the association of genetic and phenotypic variation patterns. In this study, point pattern analysis and spatial
autocorrelation were used to examine the spatial and genetic structures in two naturally generated beech stands, which differ
in age, trunk morphology, and stand management. Significant tree clumping was observed at distances up to 20 m in the young
forest stand, whereas dispersion at distances under 10 m was observed in the old stand. The spatial analysis based on Ripley’s k function of the two different groups of trees showed that the non-forked trees match in both stands the spatial pattern of
all trees while the forked were randomly distributed. Additionally, according to the bivariate analysis, forked trees in both
stands were randomly distributed as related to non-forked tree positions. Finally, Moran’s I values were not very high, though significant genetic autocorrelation was identified at distances up to 20 m in the young
stand, suggesting the existence of distinct family structures. However, no significant genetic structuring was observed in
the old stand. Our findings suggest that spatial genetic patterns are impacted by stand age, environmental factors and human
activities. The spatial distribution of forked trees was not clearly associated to family structures. Random effects and also
micro-environmental variation could be additional factors explaining forking of beech individuals. 相似文献
4.
Kwame Antwi Oduro Bas Arts Boateng Kyereh Godefridus Mohren 《Small-Scale Forestry》2018,17(3):393-410
Deforestation and forest degradation, especially in the agricultural landscapes, are serious threats to biodiversity conservation and sustainability of the timber industry. Planting trees on farms has been identified as having great potential to increase forest resources from agricultural landscapes. This paper examined farmers’ motivations and behaviour to engage in on-farm tree planting and management in Ghana by combining internal and external factors in a socio-psychological model. Data were collected from 156 smallholder farmers from five communities in two forest districts using a semi-structured questionnaire. Additional farm inventory data were collected from 33 farmers under two on-farm tree planting schemes. On-farm tree planting was perceived as providing income, access to personal timber for furniture, and access to loan facilities. Incentives such as provision of grants, farming inputs, capacity training, and access to markets for agricultural produce are factors that motivate on-farm tree planting in Ghana. The average standing volume of on-farm trees in the study area is 51.9 m3/ha which is almost twice the national average for the off-reserve areas in the semi-deciduous forests to which much of the study sites belong. Many farmers considered high financial costs and limited knowledge of appropriate techniques in managing planted on-farm trees as barriers to the development of tree stock on farms. 相似文献
5.
Over recent decades there has been a growing interest in the attributes of non-timber forest products (NTFPs) to food security, income generation, and poverty alleviation. In the Guinean Savannah Highlands (GSH) of West Africa, species producing these products are still in wild stands where they are subjected to various pressures. To conserve these species, their domestication is required. Air layering is a low-cost propagation technique easy to use by farmers. The present study aims at evaluating the effects of the wood type (hardwood, semi-hardwood, and softwood) as well as branch diameter (Φ ≤ 6.67 cm; Φ > 6.67 cm) in the rooting ability of the marcots (air-layered propagules) of Lophira lanceolata Van Tiegh. Ex Key., Parkia biglobosa (Jacq.) Benth, Syzygium guineense var. macrocarpum Engl., Vitex doniana Sweet., Vitex madiensis Oliv., and Ximenia americana L. The experimental design was a split-plot with three replications. The rooting percentage of the marcots varied significantly from 13.5 (X. americana) to 55.85% (Lophira lanceolata; p < .001). The diameter * wood type interaction was significant (p < .05) due to the high rooting percentage obtained in large semi-hardwood cuttings (40%). Lophira lanceolata, Syzygium guineense var. macrocarpum, and Vitex madiensis were the easiest marcotting rooting species. Large branch diameters as well as semi-hardwood are suitable for layering. This information will help in developing appropriate domestication strategies. 相似文献
6.
7.
[目的]研究广西国有东门林场25年生大花序桉种源生长与形质性状的遗传变异,筛选优良种源及单株,为大花序桉良种繁育及中大径材培育提供优质遗传材料。[方法]采用方差分析、构建性状选择指数方程综合分析等方法,对11个大花序桉种源进行生长与形质性状遗传变异分析及选择。[结果]表明:大花序桉胸径(DBH)、树高(H)、单株材积(V)、树干通直度(ST)和树干圆满度(SF)在种源间呈极显著差异;上述5个主要性状的种源遗传力(H2)为0.634 0.895,单株遗传力(h2)为0.136 0.342;以DBH、H、V、ST和SF 5个性状指标构建大花序桉种源/单株选择指数方程,按标准选择出4个优良种源和13株优良单株,优良种源平均材积遗传增益达11.2%,优良单株平均材积遗传增益达29.7%,选择效果尚好。[结论]大花序桉5个主要性状遗传变异在种源水平受中度至较强遗传控制,在单株水平受弱度遗传控制。优良种源D47、S14127、B47和S12195生长材性兼优,可用作培育优质中大径材。 相似文献
8.
S. E. Williams M. van Noordwijk E. Penot J. R. Healey F. L. Sinclair G. Wibawa 《Agroforestry Systems》2001,53(2):227-237
Perennial tree crops are often grown in complex multistrata systems that incorporate natural vegetation. These systems contribute
simultaneously to sustaining rural livelihoods and to the conservation of biodiversity, but their productivity is usually
low. Introduction of high yielding germplasm, usually selected in monocultural plantations, is a potential way to increase
productivity, but a critical requirement is that such plants can be established in a competitive multispecies environment.
The establishment of clonal planting stock in the jungle rubber agroforests of Indonesia was explored through participatory
on-farm research. The trial involved four farmers who grew clonal rubber trees in a total of 20 plots, constituting five replicate
experimental blocks spread across four farms. Unexpectedly, vertebrate pest damage by monkeys (Presbytis melalophos nobilis) and wild pigs (Sus scrofa) was the most important influence on establishment, explaining almost 70% of the variation in rubber tree growth. The amount
of labour invested in weeding was also positively correlated with rubber tree growth. Farmers generally decided to completely
cut back vegetation between rows of rubber trees, including potentially valuable trees, rather than weeding within the rows
and selectively pruning trees in the inter-row. Farmers thought that the inter-row vegetation would harbour vertebrate pests
and compete with the clonal rubber, and they had access to fruits, firewood and other non-timber forest products from other
land. Thus, contrary to expectations, when offered clonal germplasm, farmers opted to use plantation monoculture methods to
protect what they considered a valuable asset, rather than maintain the traditional multispecies strategy they use with local
germplasm.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
9.
Katja Kehlenbeck Roeland Kindt Fergus L. Sinclair Anthony J. Simons Ramni Jamnadass 《Agroforestry Systems》2011,83(2):133-147
Agroforestry systems are potentially suitable for conservation of tree genetic resources. Farmers around Mt. Kenya usually
integrate trees into their farm. Large parts of these trees seem to be of exotic origin, whereas indigenous species have priority
for conservation. This study aimed at determining on-farm richness, composition and frequency of indigenous and exotic woody
species around Mount Kenya to assess the suitability of farms for the conservation of indigenous tree species. 265 on-farm
plots of 0.5 ha size each were selected in 18 different agro-ecological zones by using a stratified sampling scheme. All woody
species within the plot were recorded with their local and scientific names. Total species richness was 424 (including 306
indigenous ones), mean richness per plot 16.5 species (including 8.8 indigenous ones). Eight out of the 10 most frequent species
were exotic ones with Grevillea robusta from Australia ranking first (found on almost 76% of the surveyed farms). The proportion of indigenous species increased
with increasing aridity and temperature. Dominance of exotic species was found at farms of humid mid- and highlands. Ordination
analysis revealed that mostly exotic species contributed to separation of farms in the highlands and upper midlands, whereas
indigenous species in the lower midlands and lowlands. As the frequencies of most indigenous trees were low, only parts of
the surveyed farms can contribute to conservation of tree genetic resources, particularly the less intensively managed farms
of the more arid lands. Farmers’ access to knowledge on valuable indigenous tree species and to quality seedlings of these
trees need to be improved to increase indigenous species’ frequencies on farms and possibly to replace some of the exotic
species in the future. 相似文献
10.
Woziwoda Beata Dyderski Marcin K. Parzych Agnieszka Jonczak Jerzy Jagodziński Andrzej M. 《European Journal of Forest Research》2021,140(6):1499-1514
Forest transformation from coniferous monocultures to mixed stands is being promoted worldwide, including the introduction of fast-growing broadleaved tree species within native stands. Here, we studied how enrichment of temperate European Scots pine (Pinus sylvestris) forest by North-American northern red oak Quercus rubra impacted macronutrient concentrations in two long-lived and dominant components of the forest understory: bilberry Vaccinium myrtillus and lingonberry V. vitis-idaea. Study sites were located in forest complexes (central Poland) which occupy continuously reforested lands (hereafter ancient forests) as well as post-agricultural lands (recent forests), all suitable for mesic pine forests. Samples of bilberry and lingonberry leaves, stems, and fruits were collected in pine stands and in adjacent Scots pine-red oak stands, in both ancient and recent forests. Concentrations of macronutrients (C, N, P, K, Ca, S, and Mg) in aboveground biomass components were analysed using standardized chemical procedures. The study revealed intra- and interspecific (bilberry vs. lingonberry) differences in concentrations of all nutrients in leaves, stems, and fruits, except for invariable C concentrations. Macronutrient accumulations in plants were decreased by land-use discontinuity and favoured by enrichment of tree stands by Q. rubra. The estimated macronutrient pools were much higher for V. myrtillus than V. vitis-idaea in all forest types studied. They were lower in forests enriched with Q. rubra, both ancient (up to 25.5% for bilberry and 99.9% for lingonberry) and recent (46.9% and 99.9%, respectively), as well as in recent pine forest (46.6% and 81.1%, respectively) than in ancient pine forest. Higher K and S pools (39.3% and 6.5%, respectively) noted for bilberry in an ancient forest with Q. rubra were exceptions. Despite more effective accumulations of elements at the species level, macronutrient pools of Vaccinium myrtillus and V. vitis-idaea decreased significantly in the presence of introduced Q. rubra due to negative impacts of this broadleaved tree on bilberry and lingonberry cover and biomass. Therefore, the limitation of alien Q. rubra planting in sites of mesic pine forest with the abundant occurrence of V. myrtillus and/or V. vitis-idaea is recommended.
Graphic abstract11.
Forest management is often carried out in different ways, without any appropriate environmental restrictions. Stands of pedunculate oak (Quercus robur L.) in Galicia (NW Spain) have been harvested by alternating high forest and, mainly, coppice forest. However, some totally inappropriate silvicultural treatments have been used, such as thinning of the best trees and inadequate pruning. The objective of the present study was to analyse how environmental characteristics affect the management of oak forests in Galicia. For this, a botanical inventory was carried out in 39 selected stands of Q. robur and a total of 42 parameters were measured, 4 of which were physiographical, 12 climatic, 19 edaphic and 7 silvicultural. In order to analyse the possible relationships among these variables, the silvicultural data were compared with the other data, by canonical correlation analysis. All parameters were correlated with the silvicultural regime, although the correlation was weak for the floristic data. It is therefore evident that the environmental conditions affect how forest stands should be managed, although this does not imply that more profitable use of the stands cannot be achieved than at present, and alternative silvicultural methods must be found to enable appropriate management and conservation of oak stands. 相似文献
12.
Dhiraj Naik Durgeshwer Singh Varsha Vartak Sharayu Paranjpe Sujata Bhargava 《New Forests》2009,38(1):99-115
Gmelina arborea is an important timber-yielding tree that grows naturally in the tropical and subtropical regions of Southeast Asia and has
also been introduced as a plantation species outside these regions. Genetic diversity in this tree species was observed in
stone/seed-related traits and in vitro responses of cultured nodal segments from plants of eight different populations representing
natural forests, fragmented forests and plantations. Variance analysis showed significant differences between populations
for these traits. However, it was not possible to separate the different populations using these traits by multivariate analysis,
even after environmental variation was reduced over six subcultures. Genetic diversity was therefore analysed using molecular
markers. Inter-simple sequence repeat (ISSR) primers yielded 95% polymorphic loci among the eight populations and UPGMA analysis
enabled separation of these populations on the basis of their genetic distances. Diversity was also analyzed using population
genetics parameters like Nei’s genetic diversity and gene differentiation. Nei’s genetic diversity was 0.29 between populations
and 0.11 within populations. AMOVA analysis indicated 41 and 59% within- and between-population genetic diversity, respectively.
Mantel test suggested that genetic differentiation between six Indian populations was positively correlated to geographic
distance (r = 0.626, P = 0.029). Assessment of the genetic variation in G. arborea populations is an important step in selection of conservation strategies for this species since diversity forms the basis
for species adaptation. 相似文献
13.
Zhicong Dai Chuncan Si Deli Zhai Ping Huang Shanshan Qi Ying Lin Ruiping Wang Qiongxin Zhong Daolin Du 《林业研究》2018,29(2):291-299
The endangered Vatica mangachapoi, a long-lived, tropical tree with economic and ecological importance found in Hainan, China, was used to assess the hypothesis that historical human activities in Hainan’s tropical rain forest could have negative effects on the genetic diversity of V. mangachapoi. Three hundred and twenty individuals from 11 natural populations—which were classified into three groups according to levels of disturbance—were sampled and analyzed with ISSR markers. Although genetic diversity of V. mangachapoi is high at the species level, it is relatively low within populations. A significant genetic differentiation occurs among different disturbance levels. Significant isolation-by-distance indicated relevant historical anthropogenic changes. Our findings showed that historical human disturbances significantly increase the genetic differentiation and slightly decrease the genetic diversity of long-lived tree V. mangachapoi. Relevant targeting conservation actions were recommended. 相似文献
14.
《Forest Ecology and Management》1988,24(2):139-149
Phenotypically selected individuals, to be used in a breeding program, and randomly selected individuals of white spruce (Picea glauca Moench Voss) were sampled from nine stands within a breeding region to document impacts of early domestication in a wild species. Needles from both selected and random samples were surveyed for electrophoretically detectable genic variation at twelve different enzyme systems. Average heterozygosity (0.172) was comparable to geographically broader surveys of this species. Although a large number of unique and rare alleles were observed, only 0.7% of the variations was attributable to the among-stand component. No changes in genotypic structure were associated with phenotypic selection using this set of molecular markers. Because of this lack of association, the isozymes could serve as an independent set of neutral variables to monitor variation. Allele frequency and heterozygosity were not significantly different in the selected versus random populations. There were, however, differences between the two population samples when measures of allelic richness were contrasted. Only 75% of the alleles were represented in the selected population. Implications of these changes on the utility of phenotypically selected populations as gene conservation samples, and their representativeness as breeding populations, are discussed. 相似文献
15.
16.
Tree plantations of native and exotic species are frequently used to compensate for forest loss in the tropics. However, these plantations may support lower species diversity and different communities than natural forest. We therefore investigated bird communities in stands of natural forest, different types of tree plantations and secondary forest in Kakamega Forest, western Kenya. We compared birds differing in habitat specialisation, i.e. forest specialists, generalists, and visitors. We recorded significant differences in mean species richness and number of individuals among the different forest types. Stands of natural forest and plantations of indigenous tree species comprised more species and individuals than plantations of exotic tree species and secondary forest. This was caused by a significant decline of forest specialists and generalists from natural forest and indigenous plantations to exotic plantations and secondary forest. Species composition of the bird communities did not differ between natural forest stands and plantations of a mixture of indigenous tree species, but clearly changed between natural forest and plantations of single tree species. These findings demonstrate that natural forest areas are needed for the conservation of forest bird diversity, but that plantations with a mixture of indigenous tree species can have similarly high conservation value. 相似文献
17.
The green oak leaf roller (Tortrix viridana L.) is a major pest on oaks. The green oak leaf roller is one reason within a disease complex for the oak decline, and it
leads to defoliation of oaks in spring. In Germany, Quercus robur L. is mainly affected. The partitioning of genetic variation within and among populations of forest pests is linked to their
capacities for migration. And the capacity for migration is the basis for dispersal of the pest species to different host
trees and host populations and, therefore, for further outbreak events. Thus, the within population spatial genetic structure
(SGS) of T. viridana was investigated based on nuclear (AFLP) markers to analyse the dispersal capacity of this insect pest species at a very
small spatial scale. A total of 401 individuals of the green oak leaf roller from four stands in North Rhine-Westphalia (Western
Germany) were examined. In three of four populations, the AFLP markers revealed clearly SGS up to 40 m, which can be explained
by the mating behaviour within this species. 相似文献
18.
Washington J. Gapare 《New Forests》2014,45(3):311-331
Major challenges exist for applied gene conservation of forest genetic resources in native habitats of the Mexican and Central American Pines, Pinus radiata and the Southern US pines. They include population decline and population structure changes, due to forest removal, conversion of forest land to other uses, fires, climate change, diseases and pests. However, tree breeders continue to struggle with methods that would meaningfully integrate tree breeding and conservation populations. In this review, I will start by outlining the importance of gene conservation in tree breeding programs, then highlight some challenges and opportunities for applied gene conservation programs; and lastly, I share results of a large body of applied research and other activities aimed at genetically characterising the base population of P. radiata in Australia and New Zealand, for the purposes of effective ex situ gene conservation. Main threats for species grown in exotic environments also include introduced diseases and pests, and more recently, climate change. Consequently, movement of genetic material is often restricted and genetic resources of pine species are not readily expanded by further importations from overseas. Therefore, conservation of genetic material currently in these countries is likely to be important for the long-term viability of plantation forestry using pine species. In addition to understanding the largely unpredictable or speculative biological and economic worth of rare alleles, the greatest challenge that we have in ex situ gene conservation is to develop practical approaches for infusing genes from base populations of unimproved material into more advanced-generation breeding programs without greatly affecting productivity gains. Other notable challenges include perceived costs and benefits of gene conservation in the face of increasing privatisation of forest estate. While financial resources for domestication of alternative species are declining, a vast number of existing species and provenance/progeny trials of P. radiata, the Mexican and Central American pines and the Southern US pines provide an excellent gene resource for the future. 相似文献
19.
The potential of the dry zone agro-ecosystem of southern Honduras to contribute to the conservation of Mesoamerican dry forest
tree diversity is evaluated. Four rural communities containing eight land uses were surveyed using rapid botanical sampling
resulting in the identification of 241 tree and shrub species. As a result of ordination analysis, it is concluded that the
land uses are relatively similar in their species composition, particularly maize fields (milpas), fallows, pastures and woodlots, because of the predominance of natural regeneration. Therefore all land uses might contribute
to local tree diversity conservation. Those land uses in which planting also contributes to diversity, home gardens (solares) and orchards, are more distinct; however the tree species found there are widespread and often exotics and thus not the usual
focus of conservation measures. Across the landscape the total complement of species considered a global priority for biodiversity
conservation is very low and therefore this agro-ecosystem does not represent a good place in which to implement dry forest
tree diversity conservation programmes. Instead its value is likely to be in the contribution that tree diversity makes to
rural livelihoods. Particular consideration is given to Swietenia humilis Zucc. (small leaved mahogany) and its status as a threatened species is questioned because of its abundance within this landscape
and its wide distribution.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
20.
The stem analysis ofBetula platyphylla in natural forest at the Maoershan Forest Experimental Station of Northeast Forestry University, showed that the growth variation
of the trees, including height and diameter breast height, decreases with the increase of the age. There is the turning point
for the growth variation of the tree from acute change to relative stability when the trees are in eighteen years old. There
are significant differences among the height, diameter and volume growth of the trees at that time. Therefore, the optimal
age for early selection of this species in natural stands is eighteen years old (18 a). Diameter is used as main index for
selection and height growth as auxiliary one.
(Responsible Editor: Zhu Hong) 相似文献