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1.
Michael S. Vrahnakis George Fotiadis Anastasia Pantera Andreas Papadopoulos Vasilios P. Papanastasis 《Agroforestry Systems》2014,88(5):877-893
Valonia oak (Quercus ithaburensis subsp. macrolepis (Kotschy) Hedge and Yaltirik), a deciduous species grown in the xerothermic conditions of the east Mediterranean zone of Europe, forms woodlands of open canopy that permits adequate light to reach the ground thus sustaining an exceptionally rich flora. In Greece, these woodlands are mainly used for livestock grazing and considered important silvopastoral systems. Nowadays, most of them are abandoned and degraded as a result of inappropriate management. For the effective evaluation and sustainable management of these woodlands and the establishment of reliable monitoring systems, a detailed analysis of their plant diversity characteristics across Greece is needed. This paper aims at determining and comparing floristic diversity measures as well as at assessing the impact of human activities on vegetation and floristic diversity of the most characteristic valonia oak silvopastoral woodlands of Greece. It was found that the truncated log-normal model adequately predicts the species abundance data for eleven out of the twelve woodlands. From the statistical comparison of the diversity indices Q-statistic, Berger–Parker dominance index and Shannon-Wiener measure of equitability, three groups of these woodlands can be distinguished (a) the high-richness group of Pentalofos, Lesvos, Lakonia and Thesprotia, (b) the medium-richness group of Kriti Island, Alexandroupoli, Strofylia and Galaxidi, and (c) the low-richness group of Kea Island, Amfilohia, Almyros and Lilaia. However, the Rényi’s diversity ordering diagram showed that, generally, in low levels of entropy inconsistency is the rule and no clear pattern of diversity is extracted reflecting the impact of complex factors. Among them, those related to management seem to mostly determine plant diversity of valonia oak silvopastoral woodlands, with abiotic factors having an occasionally supporting role. Changes of species richness and evenness due to livestock grazing as well as acorn and wood harvesting are further discussed. 相似文献
2.
Coert J. Geldenhuys 《Journal of Forest Research》2010,15(1):3-13
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. 相似文献
3.
Ángela Taboada Reyes Tárrega Leonor Calvo Elena Marcos José Antonio Marcos José María Salgado 《European Journal of Forest Research》2010,129(1):31-45
The aim of this study was to evaluate the influence of forest structure (mainly resulting from human uses) and forest type (the identity of the dominant tree species) on biodiversity. We determined the diversity of two taxonomical groups: the understory vegetation and the edaphic carabid beetle fauna. We selected eight types of forest ecosystems (five replicates or stands per forest type): pine (Pinus sylvestris) plantations of three age classes (10, 40 and 80 years since reforestation), an old-growth relict natural pine forest, and four types of oak (Quercus pyrenaica) stands: mature forests with livestock grazing and firewood extraction, mature forests where uses have been abandoned, “dehesa” ecosystems and shrubby oak ecosystems. The results obtained by a global PCA analysis indicated that both tree size and dominant species influenced the ordination of the 40 forest stands. In general, carabids were more sensitive to changes in forest heterogeneity and responded more clearly to the analysed structural variables than the understory vegetation, although the species richness of both groups was significantly correlated and higher in case of oak forests. Pine forest ecosystems were characterised by the lowest species richness for both taxonomical groups, the lowest plant diversity and by the lowest coefficients of variation and, consequently, low structural heterogeneity. As a result, it was very difficult to discriminate the effects of the spatial heterogeneity and the dominant tree species on biodiversity. 相似文献
4.
Composition, structure and dynamics of Dysart Woods, an old-growth mixed mesophytic forest of southeastern Ohio 总被引：1，自引：0，他引：1
Brian C. McCarthy Christine J. Small Darrin L. Rubino 《Forest Ecology and Management》2001,140(2-3):193-213
Dysart Woods is a 23 ha old-growth remnant of mixed mesophytic vegetation located in southeastern Ohio, USA. A designation of mixed mesophytic for this forest has historically been difficult, in part due to the abundance of white oak (Quercus alba); however, the dominance of a variety of other hardwoods prevents a simple oak forest designation. Using two 0.35 ha plots on opposing north- and south-facing slopes, we describe the structure and composition of the overstory, understory, and soils, 30 years after their first examination. In 1970, the woods was dominated by beech (Fagus grandifolia), white oak, and sugar maple (Acer saccharum) — historically, the three most abundant species in this region. At that time, white oak was only present in the largest size classes, was not regenerating, and was predicted to decline in importance through succession. These patterns continue today suggesting that inferences made via overstory–understory relations in regards to forest succession are relatively robust over this time period. Beech and maple have increased in importance; white oak has decreased in importance due to mortality in the larger size classes and decreasing density due to regeneration failure. Coarse woody debris distributions correlated strongly with living stem species’ composition and structure implying an equilibrium balance. CWD volume and frequency were dominated by Quercus spp. A detailed analysis of forest health showed that all oak species were in severe decline. The oaks are in a disease decline spiral affiliated with a variety of pre-disposing and inciting factors which include their advanced age (>300 years), their large size (> 100 cm DBH), topography, chronic air pollution, drought, and Armillaria root rot fungus. Ca:Al molar ratios in the soil are also extremely low (<1.0) and may be having an additional detrimental effect. All other canopy species appear to be healthy. One of the unusual features of this woods is its relatively diverse and high coverage (up to 90%) understory layer. The herbaceous community was sampled throughout the growing season and found to be markedly dissimilar among sample times and habitat productivity (aspect, soil quality, and light). The role of these factors has not been as well studied for herb communities as it has for tree communities. There appears to be a relatively strong linkage between the overstory regeneration and understory coverage. While a variety of woody seedlings were discovered, most were of shade tolerant species. Only a few small seedlings of white oak were discovered, with none advancing past 30 cm in height, indicating strong competition in the understory. Furthermore, this small remnant forest patch is surrounded by an agricultural and second-growth forest matrix with many non-indigenous plants — none of which have been able to enter the woods, suggesting strong equilibrium stability of these old-growth patches. The hardwood forests of the hills region has been heavily impacted by various human cultures for thousands of years. Dendrochronological analysis of a full basal slab cut from a wind-thrown white oak revealed a fairly active period of fire following European settlement. A lack of fire during the early 1600s to mid 1700s suggests that pre-Anglo fire frequency may have been negligible. There is clearly a continued role for the preservation and study of these old-growth remnants. They remain integrally important as we attempt to understand and better manage our remaining anthropogenically disturbed landscape. 相似文献
5.
《Forest Ecology and Management》2001,141(3):259-269
Nutrient dynamics of an Aleppo pine (Pinus halepensis, Mill.) ecosystem located in the Kassandra peninsula, Central Macedonia, Northern Greece, were studied using a chronosequence approach. The nutrient composition of the Aleppo pine trees, the understory evergreen broadleaves and forest floor in adjacent stands of 23, 48, 70 and over 100 years old was determined to estimate postfire nutrient losses. The concentration of nutrients in the Aleppo pine trees, except of Ca, was reduced with increasing stand age. Ca was the most abundant nutrient in the aboveground vegetation and in forest litter, followed by N, K, Mg and P. The accumulation of nutrients in the aboveground biomass was positively related to stand age. For younger stands nutrient accumulation was considerably larger in the understory vegetation as compared to the pines, due to substantial enhancement of the understory biomass and the number of understory species present. In middle-aged stands, however, nutrient accumulation in the understory and overstory vegetation reached a balance. In addition, considerable quantities of nutrients have been accumulated in the forest floor particularly in stands of 48 years old. Therefore, any destruction during the period of maximum nutrient accumulation in the forest floor will cause degradation of the ecosystem. It is postulated that the competition for nutrients between overstory and understory vegetation may be as important as competition in soil. Forest management practices leading to the direct conversion of the understory biomass into littermass would be of great significance for the sustainability of the Aleppo pine ecosystem. 相似文献
6.
We sought to quantify changes in tree species composition, forest structure and aboveground forest biomass (AGB) over 76 years (1930-2006) in the deciduous Black Rock Forest in southeastern New York, USA. We used data from periodic forest inventories, published floras and a set of eight long-term plots, along with species-specific allometric equations to estimate AGB and carbon content. Between the early 1930s and 2000, three species were extirpated from the forest (American elm (Ulmus americana L.), paper birch (Betula papyrifera Marsh.) and black spruce (Picea mariana (nigra) (Mill.) BSP)) and seven species invaded the forest (non-natives tree-of-heaven (Ailanthus altissima (Mill.) Swingle) and white poplar (Populus alba L.) and native, generally southerly distributed, southern catalpa (Catalpa bignonioides Walt.), cockspur hawthorn (Crataegus crus-galli L.), red mulberry (Morus rubra L.), eastern cottonwood (Populus deltoides Bartr.) and slippery elm (Ulmus rubra Muhl.)). Forest canopy was dominated by red oak and chestnut oak, but the understory tree community changed substantially from mixed oak-maple to red maple-black birch. Density decreased from an average of 1500 to 735 trees ha(-1), whereas basal area doubled from less than 15 m(2) ha(-1) to almost 30 m(2) ha(-1) by 2000. Forest-wide mean AGB from inventory data increased from about 71 Mg ha(-1) in 1930 to about 145 Mg ha(-1) in 1985, and mean AGB on the long-term plots increased from 75 Mg ha(-1) in 1936 to 218 Mg ha(-1) in 1998. Over 76 years, red oak (Quercus rubra L.) canopy trees stored carbon at about twice the rate of similar-sized canopy trees of other species. However, there has been a significant loss of live tree biomass as a result of canopy tree mortality since 1999. Important constraints on long-term biomass increment have included insect outbreaks and droughts. 相似文献
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概述了森林可持续经营的基本原则和思想 ,分析了木材生产对森林生态系统的影响 ,提出了符合森林可持续经营要求的木材生产技术措施和建议。 相似文献
9.
The amount of standing genetic diversity found in oak coppice forests has been subjected to intense debate amongst forest ecologists and managers. In this study, the level of vegetative propagation and the genetic diversity found in a coppice forest of rebollo oak (Quercus pyrenaica) was examined. The current range of rebollo oak in the Iberian Peninsula reveals its adaptation to sub-Mediterranean mountain ecosystems. High sprouting capability, mainly by root suckers, has favoured traditional exploitation of rebollo oak in coppice forests. Using nine microsatellite loci, we have detected 14 clone assemblies compounded by 2–4 stems (7.9 ± 1.3 ramets per genet, considering stand density) and covering an average surface of 11.4 m2 per genet. The levels of genetic diversity and the amount of unique genotypes were high (D = 0.9972, G/N = 0.86) and similar to the clonality levels found in a nearby open oak woodland. Despite numerous clear-cutting rotations, known at least since 1750, and the heavy root sprouting observed after a thinning event, low clonal propagation (∼27%) was detected. This fact pointed towards the long-term persistence of several small clonal assemblies in this coppice. Our findings suggest that intense thinning practices are unadvisable in the conversion of Q. pyrenaica coppice into high forest due to the significant losses of genetic diversity when removing unique genotypes. 相似文献
10.
Trade-offs among wood production, wood quality and ecological characteristics in the management of harvested forest stands are explored through model simulation of various silvicultural regimes. Long-term production of merchantable wood, production of various types of high-quality wood, and the level of certain quantitative ecological indicators are projected for coniferous forests of Pacific Northwestern USA. The set of ecological indicators used is based on the species composition and physical structure of old, unlogged forest stands. Simulations are performed with an ecological model of forest stand dynamics that tracks the fate of live and dead trees. Short rotations (<50 years) produce the least amount of high-quality wood over the multi-century simulation period. They also fail to generate ecological attributes resembling those of old forest stands. Production of high-quality wood is moderate to high under all rotations of 80 years or more; however, most ecological indicators require longer rotations unless alternatives to clearcutting are applied. Alternatives examined include retention of 15% cover of live tree canopy at each harvest in combination with artificial thinning between harvests. Thinning from below can expedite the development of large live and dead trees, and canopy height diversity without greatly diminishing wood quantity or quality. Proportional thinning retains understory stems, thereby expediting the recruitment of shade-tolerant trees. A possible drawback to thinning, particularly proportional thinning, is the diminished production of clean-bole wood at rotations of 150 and 260 years. It is concluded that most wood quantity, wood quality and ecological objectives can be met with long rotations (ca. 260 years). Certain objectives can be met with shorter rotations (80–150 years) when treatments of thinning and canopy tree retention are applied. 相似文献
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Pine plantations on selected sites in the extensive zone of degraded oak coppice of northern Greece are deemed necessary for increasing wood production in the area and suitable site preparation may accelerate early tree growth. Seven site preparation treatments including raking (R), with sub-soiling (RS), disc harrowing (RD), tine ploughing (RT) and their combinations (RSD), (RDT) and (RSDT) were compared for the establishment of black pine (Pinus nigra Arn) in an oak coppice site, of conglomerate parent material at Anthrakia, northern Greece. The randomised blocks trial of three replications and 110 trees per treatment, half of which were fertilised with 150 g NPK per plant, was assessed at the age of 15 years for diameter, dominant tree height and survival. There was no significant difference between the treatments in any of the traits examined, nor did the fertilisation had any effect. Only the fertiliser × treatment interaction was found significant at p<0.001 for dominant height, accounting for 37% of the observed variation in this trait. The lack of response to site preparation treatments may be attributed to the hard Bt3 clay horizon, extending beyond cultivation depth (50 cm), that prevents the roots penetration into deeper moist soil layers. The F × T interaction, where the combination of (RSDT) treatment and fertiliser was found to accelerate tree height growth in relation to the same treatment without fertiliser, indicates that thorough soil cultivation is needed for fertilisation to be effective in such sites. 相似文献
14.
In the southwest part of the Iberian Peninsula the dominant land-use are the Portuguese montados and Spanish dehesas, parkland
forested areas of anthropogenic origin dominated by cork oak. They form a wooded matrix with open areas, scattered woodlands
and undisturbed patches of Mediterranean forest and scrublands. The montados are characterized by a rich bird community. We
have focus our study in a multidisciplinary approach, evaluating how management and landscape patterns influence the bird
community in order to identify potential threats to its conservation. The study was conducted in the Site of Community Importance
of Serra de Monfurado were 70% of the area is cork and holm oaks. We used data from 120 10-min point counts. Using variation
partitioning, we determined the independent and joint effects of Forest, Management and Habitat variables. The variation captured
in bird assemblage was 65.06%. Most of the explained variation was related to the Habitat and Management variables. The explanatory
variables that were high-lighted as important predictors were variables that reflected tree and shrub density and cork removal.
Modelling for forest species through generalized linear models (GLM) emphasize that the management plays an important role
in the species distribution. The most important variables selected in models reflected cattle grazing and cork removal. Our
results point out that the type of management is crucial to maintain the equilibrium in bird community associated to montados.
Farmland and forest species will benefit from areas with different tree densities, small patches of Mediterranean scrubs in
the understory and correct livestock numbers. 相似文献
15.
基于森林生态系统服务功能预测21世纪上半世纪中国林地资源需求(英文) 总被引：1，自引：0，他引：1
基于森林生态系统服务概念,建立了一个新的林地资源预测模型,预测中国2010-2050年的林地资源需求。通过耦合森林生态系统服务功能与森林分类经营之间的关系,预测在假设生态公益林提供生态系统服务功能需求,商品生产林供给原木和工业用材的前提下,同时考虑了人口增长、社会经济发展目标、森林管理方式和技术进步等要素对森林资源的影响。这一模型预测表明,2010、2020、2050年林地资源的需求量将分别达到2.448×108、2.612×108、3.622×108 hm2。结论表明,未来我国森林资源存在较大缺口,尤其是缺乏以提供生态系统服务功能为主的生态公益林。建议林业部门必须注重加强森林资源可持续经营,注重提升森林生态系统服务能力。 相似文献
16.
Components of dehydration tolerance, including osmotic potential at full turgor (Psi(pio)) and osmotic adjustment (lowering of Psi(pio)), of several deciduous species were investigated in a mature, upland oak forest in eastern Tennessee. Beginning July 1993, the trees were subjected to one of three throughfall precipitation treatments: ambient, ambient minus 33% (dry treatment), and ambient plus 33% (wet treatment). During the dry 1995 growing season, leaf water potentials of all species declined to between -2.5 and -3.1 MPa in the dry treatment. There was considerable variation in Psi(pio) among species (-1.0 to -2.0 MPa). Based on Psi(pio) values, American beech (Fagus grandifolia Ehrh.), dogwood (Cornus florida L.), and sugar maple (Acer saccharum Marsh.) were least dehydration tolerant, red maple (A. rubrum L.) was intermediate in tolerance, and white oak (Quercus alba L.) and chestnut oak (Quercus prinus L.) were most tolerant. During severe drought, overstory chestnut oak and understory dogwood, red maple and chestnut oak displayed osmotic adjustment (-0.12 to -0.20 MPa) in the dry treatment relative to the wet treatment. (No osmotic adjustment was evident in understory red maple and chestnut oak during the previous wet year.) Osmotic potential at full turgor was generally correlated with leaf water potential, with both declining over the growing season, especially in species that displayed osmotic adjustment. However, osmotic adjustment was not restricted to species considered dehydration tolerant; for example, dogwood typically maintained high Psi(pio) and displayed osmotic adjustment to drought, but had the highest mortality rates of the species studied. Understory saplings tended to have higher Psi(pio) than overstory trees when water availability was high, but Psi(pio) of understory trees declined to values observed for overstory trees during severe drought. We conclude that Psi(pio) varies among deciduous hardwood species and is dependent on canopy position and soil water potential in the rooting zone. 相似文献
17.
落叶栎林对森林火灾的影响分析 总被引：5，自引：1，他引：4
根据落叶栎林的特点,着重分析了落叶栎林与森林火灾的关系,结果表明,落叶栎林不仅存在着较强的潜在地表火,而且存在着潜在树冠火危险,是栎林火灾的最大隐患之一。同时还简要分析了栎类由于长期的自然适应而对森林火灾产生的抗火机制。 相似文献
18.
Anastasia Pantera Andreas Papadopoulos Vasilios P. Papanastasis 《Agroforestry Systems》2018,92(4):921-931
Valonia oak agroforestry systems of Greece are Mediterranean systems of high natural and cultural value with distinct economic, environmental, social and historical characteristics. These systems can be silvopastoral or agrosilvopastoral, and have been used since ancient times for grazing, and acorn and wood harvesting. Acorn cup collection for use in tanning, which has been undertaken since at least the fifteenth century, was an important economic activity from the nineteenth to the mid-twentieth century contributing to the local economy and development. This overview describes the historical importance of valonia oak in Greece, and the present extent, structure, ecology, products and services of valonia oak agroforestry. The sustainability of such systems is being promoted through the sale of traditional and new products, eco- and agri-tourism, and engagement with local stakeholders. 相似文献
19.
Claudia P. Quinteros Pablo M. López Bernal Miriam E. Gobbi José O. Bava 《Agroforestry Systems》2012,84(2):261-272
Seedling browsing by livestock has been indicated as major threat for forest sustainability use. Nothofagus pumilio forests are part of the livestock raising system in Patagonia, but because of the sparse understory cover, livestock graze
mainly on flood meadows within the forest matrix. The complexity of the environment under study (forests and flood meadows)
means that an adaptive predictor is needed to evaluate the intensity of resource use by livestock in order to assess its effect
on the forest. Distance to flood meadows was evaluated as a predictor of the use intensity of the forest by livestock and
its effect on the understory. The study was conducted at three sites in Chubut Province, Patagonia–Argentina. We established
transects in the forest 320 m long, starting at the edge flood meadow-forest. In these transects, the livestock presence indicators
(soil compaction, density of feces and trails) and composition of the understory were evaluated. Generalized Linear Model
for repeated measures for longitudinal data were used. The indicators showed that distance is efficient for estimating forest
use intensity by livestock. The understory varied with distance, the cover of exotic herbaceous was higher near the flood
meadow. Far from the flood meadow, the cover was entirely composited of native species. The results support the use of distance
to flood meadows as a tool for decision making in livestock and forest management in N. pumilio forests, and for further research on livestock effect on the forest. 相似文献
20.
Alma M. García-Moreno María D. Carbonero-Muñoz María Serrano-Moral Pilar Fernández-Rebollo 《Annals of Forest Science》2014,71(8):917-926