共查询到20条相似文献,搜索用时 15 毫秒
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1THEIMPORTANTMEANINGOFCFF1.1CFFHistoricalBreakthroughofChineseEcologyEnvironmentConstructionAtpresent,theareaofwaterandsoilerosionismorethan3.6millionkm2,andthedesertifiedlandsupto1.74millionkm2,correspondto18.2oftherealmarea(ZhouShengxian,2001).ThemainreasonforwaterandsoilerosionandlanddesertificationinChinaisdestructionofforestsandcultivation,whichresultsinenvironmentaggravationandmorenaturalcalamity(ZhangPeichang,1993;ZhangZhida,1997).Atthebeginningofthecentury,Chinesegovern… 相似文献
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LI Zhongkui ZHOU Bingbing. World Forestry Institute China Academy of Forestry. P. R. China . Beijing Forestry Bureau Beijing P. R. China 《中国林业科技(英文版)》2002,(2)
Forest has a strongfunction in storing water, conserving soil and protecting farmland. In the study, based on fleld management and survey, these effects of forest in Beijing were determined and quantified. According to the principles and methodology of environment economics, the values of forest to conserve soil and water were accounted. The result shows that the total value of forest to conserve soil and water in Beijing is as much as 1129.58×10~8 yuan, in which the value of water storage is 1107.92×10~8 yuan, being 98.08% of the total. 相似文献
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Cuttings of the southeast Asian tropical rain forest tree species, Pongamia pinnata (L.) Pierre were raised in growth chambers providing a photosynthetic photon flux density (PPFD) of 60 micromol m(-2) s(-1) with either a low or a high red:far-red light ratio (LR and HR, repectively). The chambers were supplied with air containing CO(2) at a concentration of either 400 (LR4 and HR4, respectively) or 800 micromol mol(-1) (HR8 and LR8, respectively). After 4 months, leaf morphology and photosynthetic characteristics were determined. Relative to HR4, the LR4 treatment increased leaf area and total chlorophyll concentration (Chl) by 24 and 25%, respectively, but reduced leaf mass per unit area (LMA) by 19%. Elevated [CO(2)] significantly increased leaf area and LMA but did not affect Chl of LR or HR plants. Leaf nitrogen concentration was unaffected by the red:far-red light ratio but decreased significantly in seedlings in the elevated [CO(2)] treatment. Photosynthesis measured in situ under the growth conditions of ambient light and [CO(2)] (A(amb)) was 30% lower on an area basis and 14% lower on a mass basis in LR4 plants than in HR4 plants. Elevated [CO(2)] reduced the activity of ribulose-1,5-bisphosphate carboxylase/oxygenase and thus decreased light-saturated photosynthetic rate in both HR and LR plants. Elevated [CO(2)] increased mean leaf area and decreased respiration rates in both LR and HR plants. The LR8 plants had significantly higher A(amb) than LR4 plants, but similar A(amb) to HR8 plants. 相似文献
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Large forest estates actively participate in the marketing of timber in France. However, the marketing of wood from private and public large forest estates (over 25 ha) could be improved by better managing price risk in multiannual supply contracts of the timber industry: creation of compensation funds for forest owners or calls to financial markets linked to processed timber products for industrialists. But, the development of supply contracts does not mean that private or public auction procedures should be abandoned. Similarly, by supplementing “forest area development schemes”, it would be possible to increase the mobilisation of timber produced on small (1 to 10 ha) and medium (10 to 25 ha) forest estates: more forestry cooperatives or local forest agencies and a new timber pre-sale mode adapted to small forest estates are necessary (sales subject to the buyer's choice of purchasing standing timber or cut wood delivered to a depot by the seller). 相似文献
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? Context
Two-thirds of Britain’s forest area is privately owned. Thus, understanding private forest owners and managers, and their attitudes to uncertainty and change, is essential for the success of climate change adaptation policies.? Aim
The aims of this study are to (1) assess how beliefs in climate change in the private sector have influenced forest management practices; (2) identify constraints related to changes in species choice and silvicultural systems; (3) analyse the implications for implementing climate change policy in forestry.? Method
Semi-structured interviews with key informants who provide advice to, or manage woodlands in, the private forest sector in north Wales.? Results
Woodland managers and some advisers are not generally convinced of a need to adapt. They feel the future is uncertain, more usually in relation to tree disease than to climate change itself. Species choice is the principle focus of adaptation activities and reveals a deep divide in opinion. Commercial advisors look to new exotics but are inhibited by absence of markets, while small-scale owners rely more on native genetic diversity.? Conclusions
Findings that are likely to apply widely include: the influential role of forest agents in forest management decisions including species choice; lack of confidence in climate change predictions, and in markets; more immediate concerns about tree pests and diseases; demand for leadership from the public sector, and for engagement amongst the private sector. Further research is needed across a wider area to test the variability in relationship between attitudes and behaviours, and local conditions including climate change predictions. 相似文献10.
Mathilde Redon Sandra Luque Frédéric Gosselin Thomas Cordonnier 《Annals of Forest Science》2014,71(7):751-760
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Uneven-aged management systems based on selection silviculture have become popular in European mountain forests and progressively replace other silvicultural practices. In time, this trend could lead to a homogenisation of the forest mosaic with consequences on structural indices recognised as beneficial to forest biodiversity.Aims
This study was conducted to investigate the potential effects of a generalisation of the selection silvicultural system on structural diversity in the forest landscape with consequences for forest biodiversity conservation.Methods
We compared four structural indices (tree species richness, diameter heterogeneity, deadwood volume and basal area of mature trees) in five different stand types typical of the northern French Alps, using forest plot data in the Vercors mountain range. Through virtual landscape simulations, we then calculated predicted mean proportions of stand types under two different conservation strategies: (i) maximising mean index values at the landscape level and (ii) maximising the number of plots in the landscape with index values above given thresholds.Results
Multi-staged forests did not maximise all indices, the best solution being to combine the five stand types in uneven proportions to improve biodiversity conservation.Conclusion
The expansion of selection silviculture in European heterogeneous forest landscapes could enhance biodiversity conservation if other stand types with complementary structural characteristics are maintained. 相似文献11.
Vulnerability of xylem to loss of hydraulic conductivity caused by drought-induced cavitation was determined for three riparian cottonwood species in Lethbridge, Alberta: Populus deltoides Bartr., P. balsamifera L., and P. angustifolia James. These species suffered 50% loss of hydraulic conductivity in one-year-old stem segments when xylem pressure potential fell to -0.7 MPa for P. deltoides and -1.7 MPa for P. balsamifera and P. angustifolia, making them the three most vulnerable tree species reported so far in North America. The possible contribution of drought-induced xylem dysfunction to the decline of riparian ecosystems in dammed rivers is discussed. 相似文献
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Ownership is a multidimensional phenomenon that includes legal, social, and emotional aspects. In addition to legal aspects, the social and emotional aspects, “feelings of ownership,” potentially have behavioral effects. Nevertheless, these aspects are often overlooked in the research influencing the forest owners' behavior and thus their forest management decisions. This article examines how private forest owners with inherited forest holdings construct feelings of ownership toward their forests and how these constructions are reflected in their forest management decisions. Forest ownership is addressed through the theory of psychological ownership. On the basis of 15 thematic in-depth interviews, we suggest that a sense of identity and control, as dimensions of psychological ownership, can influence whether forest management decisions are guided by tradition, economic incentives, or responsibility toward property. Based on the results, a forest owner typology (restricted, indifferent, informed, and detached forest owners) was constructed, further enabling us to understand the differences among private forest owners and the roots of their forest management decisions. More generally, the study highlights the important role of emotions in forest management decisions. 相似文献
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Pedro Villar-Salvador Juan L. Peñuelas Juan L. Nicolás-Peragón Luis F. Benito Susana Domínguez-Lerena 《New Forests》2013,44(5):733-751
Mediterranean oaks frequently have poor performance in forest restoration projects. We analyzed if nitrogen (N) fertilization during nursery cultivation enhances the outplanting performance of two ecologically distinct oaks, Quercus coccifera L. an evergreen shrub, and Quercus faginea L., a deciduous tree. Additionally, we compared the sufficiency N levels of both oaks and if root growth capacity (RGC) and photosynthesis testing at low air temperature better discriminated among fertilization treatments than testing at mild temperature. Plants were cultivated under five N fertilization rates (0, 30, 75, 150 and 200 mg N plant?1) for one growing season. At the end of the cultivation period several plant material and performance attributes were measured. RGC and photosynthesis were assessed at mild temperature and cool conditions in Q. coccifera, while in Q. faginea these attributes were only analyzed at mild temperature conditions. Q. coccifera seedlings were transplanted into four terraces that imposed increasing drought stress, while Q. faginea seedlings were transplanted into an abandoned wheat cropland. Sufficiency level was higher for the tree (150 mg N plant?1) than for the shrub (75 mg N plant?1) Nitrogen-deprived Q. coccifera plants had higher frost damage than remaining treatments, which did not differ among them. Fertilization in Q. faginea did not affect photosynthesis rate but it delayed leaf senescence and abscission. RGC increased with fertilization in both species. Testing temperature did not change the effect of fertilization on RGC in Q. coccifera. Photosynthesis in cool conditions discriminated N-deprived seedlings from the remaining treatments, but treatments did not differ in photosynthesis at mild temperature. Fertilization enhanced outplanting survival in Q. coccifera, primarily in the terraces imposing stronger drought stress, while fertilization only increased growth in the terraces imposing mild drought stress. Overall, survival and growth was positively related to seedling size at planting in both oaks. Additionally, Q. coccifera survival was also positively related to RGC in the harsh planting conditions. Field growth was positively related to RGC and plant N concentration in both oaks but the relation was weak or nonexistent under harsh conditions in Q. coccifera. We conclude that fertilization in the nursery is an important tool for improving the success of oak plantations in Mediterranean continental sites, and that large and N-rich seedling have greater field performance than small and low tissue N concentration seedlings, especially in harsh field sites. 相似文献
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Decentralized forest policy has been moderately successful in delivering resource-use rights to local people. At the same time, it is possible that decentralization leads to recentralization because governments never give their authority over forest resources. Recentralization studies have paid little attention to the potential of local dynamics to lead to institutional arrangements that affect forest outcomes. This paper uses a case study of Community-based Forest Management (CBFM) in the Philippines to explore how local realities lead to the development of effective institutions for forest management. In this case study, local informal regulations of forest resource use were created through the process of settling local conflicts among competing CBFM interests, including members and non-members of people’s organizations, and frontline foresters who are working at local level. Frontline foresters played a role as coordinator of institutional arrangements that regulate local forest exploitation within the CBFM implementation process. The behavior of frontline foresters affected by their own personalities and existing social relations among residents, can deter recentralization in some ways. More attention is needed on the role of frontline foresters and non-members of people’s organization as influential negotiators in state-society relations concerning forests. 相似文献
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《Southern Forests》2013,75(4):213-220
This study tested the hypothesis that water stress increases the hydraulic efficiency of Eucalyptus nitens × E. grandis saplings as a result of osmotic and elastic adjustments. Eucalyptus nitens × E. grandis clones (NH00, NH58, NH69 and NH70) were potted in coarse river sand supplemented with a slow-release fertiliser, drip-irrigated four times daily and exposed to full sunlight for eight months. Thereafter, irrigation was withheld twice for seven consecutive days from half of the saplings of each clone, with a seven-day recovery period (regular irrigation) in-between. Relative soil moisture content did not correlate with stomatal conductance (gs) at pre-dawn and at midday. Leaves of plants subjected to the water-stress treatment wilted in 7 d, and the reduction in gs was significant at midday with no significant differences between clones. Stomatal conductance and all traits derived from pressure-volume graphs (e.g. osmotic potential at full turgor) were constant in the control treatment. There were no clear patterns in osmotic and elastic adjustments in both treatments. Root hydraulic conductance was constant between treatments and clones. However, water stress reduced shoot hydraulic conductance and stem hydraulic conductivity with significant interclonal effects. Plant biomass, leaf area and leaf weight ratio were significantly lower in the water-stressed plants, but there were no differences between the clones. In conclusion, the water-stress treatment did not introduce significant differences in stomatal conductance and tissue-water relations of Eucalyptus nitens × E. grandis clones. Interclonal variation in water-stress response was found in shoot hydraulic traits, and clone NH58 may be more suitable for planting across sites prone to moderate water stress. 相似文献
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Jaime Puértolas Juan A. Oliet Douglass F. Jacobs Luis F. Benito Juan L. Peñuelas 《Forest Ecology and Management》2010
Tube shelters were designed to protect against browsing, but they improve seedling survival in Mediterranean dry climates. Mechanisms for this response, however, are not fully understood and this knowledge can be useful to help design optimal tube shelters for Mediterranean species and climates. Our objective in this study was to determine if the positive effect of tube shelters is due to enhanced growth during the wet season or to reduced light stress during the dry season. We performed two independent experiments. In the first, we assessed root growth during the wet season in two Mediterranean species with contrasting light tolerance (Quercus ilex L. and Pinus halepensis Mill.) growing in tubes with varying light transmissivity. In the second experiment, we studied the response of a Quercus ilex plantation to different shelter treatments. Root growth during the wet season was reduced with decreasing light transmissivity in the shade intolerant P. halepensis, but not in the shade tolerant Quercus ilex. Survival of Q. ilex shaded by a mesh shelter only during summer was higher than in unsheltered seedlings and similar to the survival in tube and mesh shelters during the whole season. This suggests that shade during the dry period was the main factor explaining survival in this species. This effect could be related to the lower leaf temperature recorded in sheltered seedlings. We conclude that Q. ilex (and perhaps other late successional, shade tolerant Mediterranean species) should be planted in tubes with the currently used light transmissivity because these shelters reduce light stress in summer without impairing root growth in the wet season. However, current tubes impair root growth in P. halepensis (and likely other pioneer, shade intolerant Mediterranean species), so higher transmissivity tubes may be necessary. Optimal transmissivity for tube shelter in Mediterranean climates is species-specific and identifiable as the point that minimizes light stress during summer without impairing root growth in the wet season. 相似文献
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Staffan Jacobson Hagos Lundström Sten Nordlund Ulf Sikström Folke Pettersson 《Scandinavian Journal of Forest Research》2014,29(7):675-685
Increasing use of forest fuels for energy production is generating greater quantities of wood ash. In Sweden, it is recommended that this ash should be returned to the forest to counter soil acidification and avoid potential future nutrient deficiencies, but the effects on tree growth require clarification. Thus, 10 field experiments were established in Sweden in 1990–2006 to study the effects of adding wood ash of various origins, doses and combinations of both ash and nitrogen on stem growth in Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies L. Karst.) stands on mineral soil. Observations after 5–15 years show that growth responses were strongest when N was added, either alone or with wood ash. Growth responses to additions of wood ash without N were small and variable and statistically insignificant at all study sites. However, there were indications that adding wood ash may increase stem-wood growth at fertile sites and decrease it at less fertile sites. Hence, at fertile sites, it may compensate for the growth reductions that normally follow whole-tree harvests, at least temporarily, presumably due to its effects on soil N turnover. At less fertile sites, adding N is probably essential to counteract these growth reductions. 相似文献
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Much has been written about a supposed shift ‘from government to governance’ in many policy areas, including forest policy. However, the idea remains very much at the level of hypothesis as few empirical studies have confirmed the transition. Part of the problem is the multi-dimensional character of governance itself, which includes traditional ‘government’ as one of many possible governance modes. By providing a three dimensional picture of these potential governance modes, including overlapping institutional, political and regulatory dimensions, this article analyses the complex and incomplete character of moves towards any new governance mode in a high-profile land use planning exercise in British Columbia, that of the “Great Bear Rainforest” protected area strategy on the province's mid-coast region in 2006. Little evidence of such a shift is uncovered, despite much rhetoric to the contrary. 相似文献
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During investigations into the causes of oak decline in six Regional Forestry Directories of the Black Sea Region of Turkey, Phytophthora spp. were obtained from one region and Pythium spp. were collected from three regions. The most frequently isolated Pythium species, Pythium anandrum, when inoculated on stem bases, caused longer cankers than two isolates of both Phytophthora plurivora and 2 of the P. quercina. This is the first report of Pythium anandrum causing disease on sessile oak. P. anandrum may contribute oak decline in Turkey. 相似文献
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We demonstrate a method for evaluating the appropriate number of samples required to estimate plant species richness in different
forest types within a forested landscape. In each of 36 plots (0.1 ha each) from 5 forest types (deciduous broad-leaved secondary
forest and 4 categories of coniferous plantation classified according to stand age) in central Japan, 40 quadrats of 1 × 1 m
were set in a regular pattern; the total number of quadrats in each forest type ranged from 200 to 400. In each plot, the
number of observed species in 40 quadrats ranged from 60 to 80% of the number of species estimated by the rarefaction method
for each forest type. Sampling 30 quadrats detected approximately 90% of the observed species in each plot that were detected
using 40 quadrats. In specific functional groups (i.e., tall trees and weed species), the ratios of both tall trees and weed
species to all species were at equilibrium for 30 or more quadrats. For fewer than 30 quadrats these ratios were highly variable.
No significant differences were found among forest types in the ratio of the observed number of species in each plot to the
estimated number of species calculated using the rarefaction method, and in sampling efficiency estimated by use of non-parametric
estimators. We concluded that the number of samples does not need to be changed according to forest type or plantation stand
age in the studied landscape, and that the method used to evaluate the number of samples could be useful. 相似文献