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1.
During the last century the boreal forests of south-eastern Norway have been converted into patchworks of agricultural areas, clear-cuts and even-aged conifer monocultures. Even though Scandinavian forest ecosystems are strongly influenced by small mammals’ dynamics, the effects of anthropogenic changes on these communities are still debated. We conducted an extensive capture–mark–recapture study to examine the relative abundance and distribution of 11 species of small mammals during the reproductive season with respect to all available landscape-scale habitat types and fine-scale vegetation characteristics.  相似文献   

2.
The short-term effects of selection cutting of different intensities on the forest structure and species diversity of evergreen broad-leaved forest in northern Fujian Province were investigated and analyzed. The results showed that selection cutting of low and medium intensities caused little variation in the forest structure. After cutting, the dominant species retained their leading status in the community. However, the community structure changed significantly following selection cutting of high and extra-high intensities; the status of the dominant species of the community declined dramatically. Some tree species began to disappear from the sampling plots. Except for extra-high intensity cutting, the diversity of tree species did not change significantly for the other three cutting intensities. However, the evenness of the stands was very different among the four kinds of cutting plots. For low and medium intensity selection cutting, the evenness declined slightly. For extra-high intensity selection cutting, the evenness increased to some extent, which might be due to a more even distribution of tree species after cutting. Cutting operations resulted in some adverse reactions to development of arborous species diversity of evergreen broad-leaved forest, particularly serious damage to the forest canopy. But the rational selection cuttings, which may benefit the restoration and maintenance of species diversity over a long period and may come about from the variations in environmental factors such as sunlight, temperature and humidity.  相似文献   

3.
European Journal of Forest Research - Research on mixed forests has mostly focused on tree growth and productivity, or resistance and resilience in changing climate conditions, but only rarely on...  相似文献   

4.
The aim of this study is to clarify the roles of researchers in forest policy development processes. Comparative case studies between Japan and Sweden were conducted. The research–integration–utilisation (RIU) model on scientific knowledge transfer was employed as a framework. Based on the RIU model, ‘scientist’, ‘integrator’, and ‘policy entrepreneur’ were defined as three hypothesised roles of researchers, discussed in conjunction with Pielke's ‘honest broker’ model. It was found that researchers played important roles, both as scientists and integrators in Japan. In Sweden, researchers played only the role of scientist. However, no researchers working as policy entrepreneurs were found in either country. These results indicate that the RIU model could work as a basis for the comparison between countries and the clarification of the roles of researchers in forest policy processes. The case study analysis also specified three additional topics for further discussion: (1) different types of science-based policy advice; (2) the relationship between power allies and consensus building; and (3) the reason why the roles of researchers differ between Japan and Sweden.  相似文献   

5.
Roads are recognised as having different ecological roles such as barrier, corridor or habitat, but the spatial extent of road effects on plant communities in forests remains unclear. We studied the effect of forest road distance on plant understory diversity at 20 sites in young and adult oak stands in a French lowland forest with a long history of management and road construction. All vascular and bryophyte species were collected at five distances ranging from the road verge to 100 m into the adjacent forest stand. We analysed species composition, individual species response, a priori life-history traits response – life form, habitat preference and dispersal mode – and environmental indicator values in relation to road distance and stand age. Plant composition strongly differed between road verge and forest interior habitats. The main road effect extended less than 5 m into the forest stand. A third habitat was detected at the forest-road edge resulting from the road effect on light and soil conditions, and from edge-specific topography. Non-forest species were almost absent from the forest interior. In contrast, many bryophytes and several vascular plants kept away from the road. We identified a posteriori six species groups that better explained the variability of plant response profiles than a priori life-history traits. Plant response to road distance was also dependent on stand age: some species colonised from the road into the forest interior in young stands following regeneration cutting, while other species displayed the reverse pattern in adult stands once canopy closed above the forest road. Even if the depth of forest road effect measured in lowland managed stands was narrow, building of a new forest road has non-negligible effects on plant population dynamics. Forest managers should take into account the impacts of roads on biodiversity, since the expected intensification of silviculture in response to global changes is set to accentuate the effect of forest roads. We recommend further study on the role of dispersal by vehicles (i.e. agestochory) in road effects.  相似文献   

6.

The main objective of this case study was to explore the possible influence of forest management on the levels and distribution of biomass and carbon (C) in even-aged stands of Norway spruce [Picea abies (L.) Karst.] in Denmark. Data originated from a long-term thinning experiment and an adjacent spacing experiment at stand ages of 58 and 41 years, respectively. Biomass of 16 trees from different thinning and spacing treatments was measured or partly estimated, and soils were sampled for determination of C stocks. All trees in each plot were measured for stem diameter and some for total height, to allow for scaling-up results to stand-level estimates. For trees of similar size, foliage biomass tended to be higher in the spacing experiment, which was located on slightly more fertile land. Foliage biomass increased with increasing thinning grade, but the effect could not be separated from that of tree size. At stand level, foliage biomass tended to increase with increasing spacing as well as with increasing thinning grade. For branchwood, stems and roots (including below-ground stump), the biomass increased with increasing tree size and stand volume at tree and stand level, respectively, but no differences between stands, spacings or thinning grades were observed, apart from that expressed by tree size or stand volume. At stand level, C stocks of all biomass compartments decreased with increasing thinning grade, while the distribution between compartments was hardly influenced. The ratio between above-ground and stem biomass was about 1.21 at stand level, while the ratio between below- and above-ground biomass was about 0.17. Thinning influenced the C stock of the forest floor and mineral soil oppositely, resulting in no effect of thinning on total soil C.  相似文献   

7.
8.
This study was aimed to investigate structure–function relationship of 20(S)-panaxadiol (PD) and its epimeric derivatives ((20S, 24S)-epoxy-dammarane-3β, 12β, 25-triol, PDD1 and (20S, 24R)-epoxy-dammarane-3β, 12β, 25-triol, PDD2) in myocardial ischemia injury in rats. It was shown that PD and PDD2 resulted in a reduction in creatine kinase activity. PD and PDD2 inhibited the elevation of malondialdehyde content, the reduction of superoxide dismutase and glutathione peroxidase activities. The pathohistological changes were ameliorated by PD and PDD2. The configuration of C-24 of funan ring was linked to the pharmacological action of 20(S)-panaxadiol and its epimeric derivatives.  相似文献   

9.
Studying contents and seasonal dynamics of active organic carbon in the soil is an important method for revealing the turnover and regulation mechanism of soil carbon pool. Through 3 years of field sampling and lab analysis, we studied the seasonal variations, content differences, and interrelationships of total organic carbon (TOC), light fraction organic carbon (LFOC), and particulate organic carbon (POC) of the soil in the forest areas burned with different fire intensities in the Daxing’anling Mountains. The mean TOC content in the low-intensity burned area was greater than that in the unburned area, moderate-intensity, and high-intensity burned areas in June and November (P < 0.05). LFOC and POC in the low-intensity burned area were greater than that in either moderate-intensity or high-intensity burned areas, with significant differences in LFOC in September and November (P < 0.05). A significant difference in LFOC between the unburned and burned areas was only found in July (P < 0.05). However, the differences in POC between the unburned and burned areas were not significant in all the whole seasons (P > 0.05). Soil LFOC and POC varied significantly with the seasons (P < 0.05) in the Daxing’anling Mountains. Significant linear relationships were observed between soil TOC, LFOC, and POC, which were positively correlated with soil nitrogen and negatively correlated with soil temperature in the Daxing’anling Mountains.  相似文献   

10.
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