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1.
Abstract

Swedish forest commons are collectively owned and managed by shareholders who always also own other forest holdings. The majority of them are non-industrial private forest (NIPF) owners. The objective of this study was to assess differences, with respect to harvesting intensity and related business activities on their individually managed forest properties, between non-shareholders and shareholders in a Swedish forest common. Forest commons are intended to promote local agriculture and forestry and to serve as a model for forestry activities. On this basis, the hypotheses examined in this study were that the shareholders’ harvesting and business activities, as well as their contributions to the local economy, are greater than those of non-shareholders. An apparent difference between shareholders and non-shareholders was found, but it was unexpected since non-shareholders undertook more harvesting and business activities than shareholders, and contributed more to the local economy through taxes. Since no evidence was found for a significant difference between the two categories in their potential to undertake forestry activities, one provisional conclusion is that the outcome is partly due to differences between the institutional frameworks in which shareholders and non-shareholders operate and the impact of these frameworks on incentives to maximize forest production.  相似文献   

2.
Saturated hydraulic conductivity (Ks) is an important soil hydraulic parameter for charactering the rate of water flow across the soils and is mainly related to its high spatial variability. In a small watershed with the area of 0.27 km2 in the Loess Plateau, Ks of 197 soil samples under different vegetations and landforms were measured. Ks had a moderate variability for total samples. The forestland had high Ks with low coefficient of variation (CV), but the grassland in the watershed bottom had low Ks wit...  相似文献   

3.
We studied infiltration and fractal mechanisms on sloping farmlands in a small watershed in Shandong Province in the rocky mountain areas of northern China.We studied soil fraction and soil water retention curves,and developed a soil infiltration model to analyze its quantitative relationship with soil particle size and pore dimensions under four types of land use,including sloping farmland,abandoned land,natural forest,and forest plantation(Malus pumila,Crataegus pinnatifida).Soil stability infiltration rate ranked as sloping farmland>abandoned land>natural forest>forest plantation.The sequence of soil particle size and pore dimension ranked as natural forest>forest plantation>abandoned land>sloping farmland.There were significant positive correlations between soil particle size and pore dimension,and both were positively correlated with the percent volume of silt and clay.They were negatively correlated with soil infiltration rate.The Horton model and the power function model were more suitable for simulating soil infiltration and the infiltration rate.We concluded that the soil in this area displayed typical fragments of rocky mountainous regions due to the loss of silt and clay caused by cultivation on sloping farmland.The uniformity and fractal dimensions of soil particle sizes and pore distribution decreased,thereby enhancing soil infiltration capacity and decreasing soil water retention capacity.  相似文献   

4.
In order to understand the effects of thinning on microsite conditions and natural regeneration in the larch plantation, thinning experiment was conducted in a 40-year-old Larix olgensis plantation in Qingyuan County in eastern Liaoning Province, China in 2003-2004 Five thinning treatments (0%, 10.2%, 19.8%, 29.7% and 40.3% thinned) were designed on the same site. After thinning, canopy openness and the microsite conditions such as photosynthetic photon flux density (PPFD), soil moisture content, and soil temperature were measured in one growing season. Meanwhile, the investigation of natural regeneration was conducted at the end of the growing season. The results showed that the canopy openness increased with the increase of thinning intensities. PPFD and soil temperature and soil moisture content in different soil layers were positively relative with canopy openness after thinning. The richness of regenerating tree species did not significantly increase (p=0.30) after one growing season since thinning, but the regeneration density and frequency of tree species increased significantly (p〈0.05). In addition, the number of regenerating tree species increased, and the increment was correlated with the characteristics of iudividual tree species. The increasing percentage of regenerating seedlings of the shade-intolerant tree species was more than that of shade-tolerant tree species. Among the investigated regeneration species, the biggest response of seedling emergency to the canopy openness was Phellodendron amurense. This paper confirmed the following conclusions: after thinning, the variety of regenerating tree species was correlative with the characteristics of regenerating tree species, and the distribution of unthinned trees and the site conditions in the investigated larch plantation were the additional factors influencing, the regeneration.  相似文献   

5.
Acacia karroo is an indigenous, strong drought-tolerant and widely planted tree in South Africa. In order to match the plant with its adaptation to forest sites in China, it is important to know the drought-tolerance of this species under Chinese forest site conditions. Our study was carried out in cinnamon soils in Beijing and with Platycladus orientalis, the most drought-tolerant tree in Beijing, as control. Physiological parameters of young plants of the trees were measured and divided into three groups in response to soil drying. The first group included root activity, ABA content in roots and peroxidase (POD) activity in leaves. Their values changed similarly to those of P. orientalis and dramatically increased to maximum values when the soil water content (SWC) decreased from its normal level of 20% to 7.6% where the three indices decreased dramatically when SWC was reduced further from 7.6%. The second group of parameters included the contents of proline, soluble protein and malondialdehyde (MDA). Their values showed greater variation than those of P. orientalis and significantly increased when SWC decreased from 20% in response to soil drying. However, the proline and soluble protein contents fluctuated in A. karroo at a lower level than those in P. orientalis. In contrast, the content of MDA in A. karroo was much higher than that in P. orientalis which almost did not increase in the drying soil. The third group of parameters consisted of soluble sugar, superoxide dismutase (SOD) and catalase (CAT). These parameters showed greater diversity and fluctuations among the three varieties of A. karroo compared with the control in response to soil drying. These results suggest that A. karroo is characterized as a strong, drought tolerant species in most of physiological parameters but weaker than P. orientalis in membrane lipid antioxidation.  相似文献   

6.
Academic scholarship and development paradigms promote non-timber forest products (NTFPs) as potential options to link environmental conservation with sustainable economic development objectives for rural communities worldwide. The açaí berry (Euterpe oleracea) is a native palm found in forest ecosystems of northern Brazil and historically extracted and sold in regional markets. Recent increases in national and international açaí demand have resulted in dramatic price increases. Management decisions on a local producer level reflect trends not typically associated with traditional NTFPs as future production and income expectations increase. This case study draws on research conducted in peri-urban communities in close proximity to Belém, Brazil. The work draws links between recent açaí intensification trends in upland areas and information pathways that are contributing to this pattern. This paper argues that external information sources regarding land use choices are prioritized over local knowledge and market indicators which previously have been described as drivers for intensification processes of NTFPs. This qualitative analysis highlights the power structures that influence information sharing and in turn, land use choices on a community level. The results of this analysis are important for NTFP intervention initiatives focused on risk management for smallholders. Finally, this study is a useful complement for ecological studies currently being conducted on intensification processes of non-timber forest products.  相似文献   

7.
Rhizophora mangle L. dominated 10 overwash islands within Tampa Bay forming the northernmost mangrove forests on the west coast of Florida. The mean number of trees and basal area were 5040 trees ha-1 and 20.5m2ha-1, respectively. Basal areas ranged from 1.1 (Avicennia germinans (L.) Stern), to 2.6m2ha-1 (Laguncularia racemosa Gaertner), to 16.8 (R. mangle). Cockroach Bay mangroves are small (5.8–7.0m tall) versus coastal forests of south Florida and the Caribbean. Total litter production for a 12 month period was maximal in September for fringing (7.4gdwtm-2d-1) and interior (8.7gdwtm-2d-1) areas with the two zones not being significantly different. Average litter fall (3.1gdwtm-2d-1) was similar to more tropical Caribbean mangals. Leaves accounted for 68 of the litter and reproductive material for 6, being similar to tropical riverine and overwash marine angiosperm communities on the Mexican coast. Although mangrove forests in Tampa Bay are small in stature and experience cold damage and occasional frosts, their litter fall is similar in biomass to that of more tropical mangals. However, their reproductive output is low based on litter fall versus more tropical mangals suggesting that the northern extension is less than optimum. Macroalgal diversity was low (10 species) as compared to Caribbean mangals. Macroalgal turf (0.8gCm-2d-1) and epiphyte communities of A.germinans pneumatophores (2.7gCm-2d-1) have productivity levels that are equal to or greater than those of Caribbean mangals.  相似文献   

8.
There is increasing interest worldwide in using tree harvesting biomass as an energy source. Bark retained on logs is commonly used as an energy source, but is generally removed from eucalypt logs during harvest. In order to evaluate the potential use of eucalypt bark as fuel, there is a need for information on the productivity and cost implications of retaining eucalypt bark during harvest operations. The study examined the impact of retaining bark on logs on the productivity and costs of a whole?tree to roadside harvesting system in a short?rotation Eucalyptus nitens plantation in Australia being harvested for pulp logs. Trees were felled and bunched with a feller?buncher in spring, then left infield for four weeks to promote bark adhesion and reduce bark loss. A skidder extracted the trees to roadside where a processor processed them to predominantly 10?m logs. Machine productivities were calculated from estimated tree and log volumes and cycle times recorded from video recordings. The feller?buncher's productivity (65 m3 PMH0?1) was less than expected as it appeared to be underpowered to handle the larger trees on the study site. The skidder's productivity (56 m3 PMH0?1) was comparable to those reported in studies under similar conditions and with bark retained. The roadside processor's productivity (25 m3 PMH0?1) was lower than expected. This was believed to result from the operator separately stacking 10?m and 5?m logs, and the lower feed speed resulting from slippage due to the reduced feed roller pressure used in the study to reduce bark loss. Future research could identify feed rollers that increase feed speed while retaining bark. Harvest system costs (AUD18 GMt?1) were similar to those reported for a eucalypt roadside processing trial where bark was removed. These results suggest that retaining bark on the logs at roadside did not affect the harvesting system's productivity or costs.  相似文献   

9.
Background: The Siberian moth (Dendrolimus sibiricus) (SM) defoliates several tree species from the genera Larix, Piceo and Abies in northern Asia, east of the Urals. The SM is a potential invasive forest pest in Europe because Europe has several suitable host species and climatic conditions of central and northern Europe are favourable for the SM.
Methods: This study developed a grid-based spatio-temporal model for simulating the spread of the SM in case it enters Europe from Russia via border stations. The spread rate was modeled as a function of the spatial distribution of host species, climatic suitability of different locations for the SM, human population density, transportation of moth-carrying material, and flying of moths from tree to tree.
Results and conclusions: The simulations showed that the SM is most likely to spread in the forests of northeast Belarus, the Baltic countries, and southern and central Finland. Climatic conditions affected the occurrence of the SM more than human population density and the coverage of suitable host species.  相似文献   

10.
In order to improve the understanding of the role of a canopy opening/gap on the physical environments in a secondary forest in Northeastern China, a case study was conducted in and around a small irregular gap in a montane secondary forest. The secondary forest, which was severely disturbed by human beings about 50 years ago, was dominated by Quercus mongolica and Fraxinus rhynchophyllaan. Temporal variation in photosynthetic photon flux density (PPFD), air temperature (TA) at 10 cm above the ground, soil temperature (Ts) and soil water content (SWC) at top-layer (0-15 cm) and sub-layer (15-30 cm) were measured from May to September after the second year since the formation of the small gap (the ratios of gap diameter to stand height were less than 0.5) in 2006 respectively. Results indicated that the highest value of PPFD occurred at the northern edge of the gap, particularly at the beginning of the growing season in May. On sunny days, the highest value of PPFD appeared earlier than that on overcast days. Maximum and mean values of TAwere higher in the northern part of the gap, and the minimum values of TAwere at the southern edge of the gap. Soil temperature varied obviously in the gap with the range from 1 to 8 ℃. Maximum values of Ts occurred at the northern part of the gap, which was significantly correlated with the maximum values of TA (R = 0.735, P〈0.05). SWC was higher in the top-layer (0-15 cm) than that in sub-layer (15-30 cm), but the difference of them was not significant (p〉0.05), which might be attributed to the small gap size and the effects of aboveground vegetations. From these results, the maximum of PPFD in the study area occurred at the northern part of the gap, which was consistent with the results observed in north hemisphere, but the occurrence time varied with the differences of the latitudes. The highest values of air and soil temperatures also occurred in the northern part of the gap because they were affected by the radiation. However  相似文献   

11.
12.
The recombinant expression vectorpET43. lb-AFP, which contains full encoding region of a carrot 36 kD antifreeze protein (AFP) gene was constructed. The recombinant was transformed into expression host carrying T7 RNA polymerase gene (DE3 lysogen) and induced by 1 mmol. L-1 IPTG (isopropyl-β-D-thiogalactoside) to express 110 kD polypeptide of AFP fusion protein.The analysis of product solubility revealed that pET43. 1b-AFP was predominately soluble, and the expressed amount reached the maximum after the IPTG treatment for 3 h.  相似文献   

13.
Interactions between value-creating activities are vital to increasing product value. Information sharing is a cornerstone of such interactions. For a forest-owning company with the primary objective to be leading in selling roundwood to forest industries, it appears therefore crucial that the sales people within a forest company have up-to-date knowledge about the forest in planning their sales, and that the forest knowledge is presented in a format that is suitable for them. To investigate if this is the case, a study was conducted at Sveaskog, a large Swedish forest-owning company. Semi-structured interviews were conducted with respondents from different levels in the organization. The results show that most sales managers did not directly use the knowledge about the forests when planning their sales; instead, they relied on historical data and had low trust in the knowledge presented in the tactical forest plan. The study pinpoints the organizational obstacles for using forest information in sales planning. These obstacles need to be addressed if more sophisticated information made available through new technology is to be utilized.  相似文献   

14.
To halt biodiversity loss in the humid tropics of developing countries, it is crucial to understand the roles and effects of human-modified landscapes with fragmented forest remnants in maintaining biodiversity while fulfilling the demands of local communities and reducing poverty. To implement appropriate landscape planning for conserving biodiversity and ecosystem functioning, appropriate information is required about parameters of habitat suitability among various anthropogenic habitats with a range of distances to forests and vegetation characteristics, but such information is limited. We examined differences in avian communities between a remnant forest and four types of man-made forest (two mature plantations and two agroforests) in a forest–agricultural landscape of West Java, and we analyzed the effects of both local and landscape factors on various types of species richness in this landscape. The results from non-metric multidimensional scaling revealed avifauna in the two types of agroforest was clustered separately from that in the remnant forest, mainly because drastic declines in the abundance of forest specialists (including IUCN red-listed species) and their replacement with open-habitat generalists. The mixed-tree agroforests were colonized by 30 % of forest specialists and forest-edge species found in the remnant forest, and maintained the highest richness of species endemic to Indonesia among man-made forests, implying that some forest specialists and endemics might have adapted to ancient landscape heterogeneity. High proportion of insectivorous birds was found in the remnant forest (more than 50 %) and drastically decline in man-made forests, although the species richness of insectivores did not decline significantly in broad-leaved plantations. We concluded that protection of remnant forests should be prioritized to conserve forest bird diversity. However, as different environmental factors affected the richness values of different ecological groups, appropriate landscape design and habitat management could improve functional diversity in forest–agricultural landscapes in the tropics.  相似文献   

15.
Mao'ershan region is representative in the natural secondary forested region of the eastern mountainous region, northeast China. The landscape nearest neighbor index and landscape connectivity index were calculated with ARC/INFO software for Mao'ershan region. The spatial distribution of the landscape of the region was analyzed. The results showed that the landscape connectivity index of non-woodland was significantly higher than that of woodland. The landscape connectivity index of natural forest was nearly equal to zero, which means its fragmentation degree is high. The nearest neighbor index of plantation was lower than that of natural forest and non-forestland. Among the man-made forests, the distance index of the coniferous mixed plantation is the lowest, and its pattern is nearly glomeration. The landscape pattern of natural forest presented nearly random distribution. Among non-forest land, the distance index of cut blank was the lowest, and its pattern was also nearly glomeration. Foundation item: This paper was supported by the Key Project of State Department of Science Technology (2002BA515B040). Biography: LI SHu-juan (1977), female. Lecture in Ocean University of China, Qingdao 266003, P. R. China. Responsible editor: Zhu Hong  相似文献   

16.
Based on investigation of 53 gaps and 25 quadrats (15m×15m each) of non-gap closed stand in an old-growth tropical montane rain forest of Hainan Island, China, canopy disturbance regimes and gap regeneration were studied. Gaps were elliptical in horizontal form, the ratio of long axis /short axis was about 1.4. Percentage of expanded gaps (EG) and canopy gaps (CG) area in the landscape were 53.5% and 25.2% respectively. EG ranged from 31.4 m2 to 488.2m2 and CG/rom 14.9m2 to 354.2m2, their average sizes were about 160 m2 and 80m2 respectively. Natural disturbance frequency for canopy gaps  相似文献   

17.
Four experiments were established on the semi-arid west coast plain of South Africa during the 1990s. The trails tested the survival and growth of several eucalypt species and hybrids, some of which were established in a climate that is drier than their natural distribution range. The aridity indices (AI; defined as mean annual precipitation [MAP]/mean annual potential evapotranspiration) ranged from 0.21 to 0.36 and MAP from 228 to 423 mm. The driest trial site (AI = 0.21 and MAP = 228) had high levels of mortality. However, a number of species (in particular, Eucalyptus gomphocephala, E. camaldulensis and E. tereticornis, as well as individual hybrids of the latter two species with E. grandis) survived and grew well at the remaining sites. Eucalyptus cladocalyx survived well and attained competitive growth rates only on the wettest site in the group (AI = 0.36). The dominant height of the top-performing genotypes at age 5 ranged between 9 and 10 m on the two wetter sites. This corresponded to mean annual increment values in excess of 10 m3 ha?1 a?1, which is comparable to volume obtained at more favourable aridity indices in the summer rainfall zone of South Africa and exceeds the growth rates obtained in several other arid zone studies globally. The E. grandis × E. camaldulensis hybrid ranked among the top performers in two trials, but its susceptibility to recently introduced pests and relatively poor wood quality makes it a less attractive choice for planting. The high density and durability of timber, acceptable growth rate (given the low rainfall conditions), and low pest and disease incidence make E. gomphocephala and E. cladocalyx the species of choice for planting in the drier and relatively wetter sections of the semi-arid zone, respectively.  相似文献   

18.
In South Africa, commercial eucalypt stands may be regenerated through the stepwise reduction of coppice shoots following felling. The development of secondary coppice regrowth following these reduction operations results in competition with the remaining stems, possibly resulting in a reduction in growth. Currently, secondary coppice regrowth is controlled manually, or through spraying with glyphosate at 0.6% when ca. 0.75?m in height. No research has been conducted to determine whether alternative rates and/or timing of application are possible or cost-effective. In 2006 a trial was implemented in Zululand, South Africa on a recently coppiced stand of Eucalyptus grandis × Eucalyptus urophylla so as to optimise rates of glyphosate application (0.6%, 1.2% and 1.8%) for the control of secondary coppice regrowth at various heights (0.5, 1.0 and 1.5?m). Tree and secondary coppice regrowth variates were measured annually until rotation-end (9 years, 3 months). The volume of herbicide used, the number of occasions each treatment was sprayed and associated costs were combined to provide an indication of the most cost-effective treatment. Although there were no significant differences in final coppice yield for the various rates of glyphosate and timing of application (as assessed by the size of the secondary coppice regrowth) tested, treatment efficacy in terms of treating secondary coppice regrowth increased with an increase in the rate of glypho- sate applied (0% < 0.6% < 1.2% < 1.8%), especially when treated at either 1.0 or 1.5?m in height. The use of glypho- sate, irrespective of rate and/or timing of application (as assessed by secondary coppice regrowth height), proved to be more cost-effective compared with manual control or the spraying of the secondary coppice regrowth at 0.75?m height with 0.6% glyphosate. The most cost-effective treatment was 1.2% glyphosate applied when the secondary coppice regrowth was 1.5?m. If reduced herbicide use is a major criterion within a company portfolio, then the secondary coppice regrowth can be manually removed when 1.5?m.  相似文献   

19.
In this study, the spatial distribution of nutrient stocks (K, Ca, Mg and P) was examined in humus and soils at the forest massif scale (Fougères forest, France). A random stratified sampling plan including 100 sampling points was used and three potential variation factors of nutrient stocks were tested: age of stand, type of stand (broad-leaved or coniferous trees) and type of soil. Sampling classes were then compared and the variation factors were examined. Results demonstrated that nutrient stocks in the humus were not influenced by the cited factors and only the type of soil influenced nutrient stocks in soils. In fact, stocks of exchangeable elements in soils were much higher in Colluviosols-Fluviosols which show redoximorphic characteristics, and available phosphorus stocks were lower than in Alocrisols-Neoluvisols. Moreover, a low variability of nutrient stocks was observed in Alocrisols-Neoluvisols as opposed to Colluviosols-Fluviosols, which may suggest the existence of other variation factors not taken into account in this study (hydromorphic gradient, type and age of stand in hydromorphic zones).  相似文献   

20.
The land-cover/use change dynamics in Manica Province in Mozambique are analysed, based upon interpretation of LANDSAT images, to assess trends and highlight management suggestions considering current policies in place that include the ownership and participation of local communities in natural resources management and the recognition of traditional ownership systems. Applying an object-oriented approach to compare the year 2004 with 1990, one observes that land-cover/use changes are not distributed evenly in the province. A substantial decrease in areas with trees belonging to the ‘miombo ecosystem’ occurred and an increase of cultivated areas. The nature of agriculture is changing from shifting cultivation to more permanent types. These changes are found in prevalence on gentle slopes and close to the road network.  相似文献   

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