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1.
This paper attempts to determine whether and to what extent forest birds take the risk of feeding in an open area in winter. In each of three plots the extra food (lard) was initially placed on the border of the forest and open area and then moved into the open area and located within 15, 30 and 45 m from the edge of the forest. Only in one plot the total number of all the birds feeding on lard significantly decreased along with the food being moved away from the edge of the forest. In other plot the number of the most numerous Great Tit Parus major and Blue Tit Cyanistes caeruleus significantly increased along with the food source being moved away into open area. The numbers of the other 7 species of birds fell or did not have directional nature. Only in one plot the aggregation (the number of individuals of a given species feeding simultaneously) increased significantly along with moving the food into open area. In other plots differences in aggregation did not have the directional nature and, in most cases, were not significant.  相似文献   

2.
The needles of juniper growing in spruce and birch forests of the Khibiny Mountains have been analyzed to evaluate the pattern of changes in their chemical composition (ADF, lignin, cellulose, lignin/cellulose, lipids, phenolic compounds, proanthocyanidins, flavonoids, N, C, and also Ca, Mg, K, Mn, Zn, P, S, Al, and Fe). It has been shown that the concentrations of lignin, lipids, phenolic compounds, Ca, Al, and Fe in the needles increase with age, while those of flavonoids, soluble and bound proanthocyanidins, N, P, K, Mg, Zn, and Mn decrease. The needles of juniper from spruce and birch forests differ in the contents of nutrient elements, which is explained by differences in the composition of soils. The contents of lignin, cellulose, and lipids in aging needles are lower in birch forests than in spruce forests.  相似文献   

3.
We are accustomed to solve the problem of the water scarcity in the western region by the thought of increasing the effective supply of water to meet the needs of Go-west Campaign. After introducing the dynamic equilibrium principle on supply and demand in economy, we find that we should solve the problem of the water scarcity in the western region through reducing total demand to achieve the dynamic equilibrium of supply and demand. Finally water resources in the western region can be enlarged by an accumulated way.  相似文献   

4.
The species composition of Odonata facultatively associated with forest ecosystems at the adult stage have been studied in the forest–steppe of Central Chernozem region. Factors facilitating the entry of adult dragonflies deep into forested areas, specific features of their behavior in the forest, and the role of human activities in the spread of these insects in forest ecosystems have been elucidated.  相似文献   

5.
Fertilization with 2.5 t/ha limestone: (83% CaCO3, 8% MgO, 6% K2O, 3% P2O5) reduces the 137Cs transfer from spruce forest soil into plants like fern (Dryopteris carthusiana) and blackberry (Rubus fruticosus) by a factor of 2–5 during at least 11 years as measured by the aggregated transfer factor Tag. In 1997 and 2006 these results were confirmed by additional measurements of the 137Cs transfer factor TF, related to the root zone (Oh horizon), which were explained by the selective sorption of 137Cs in the root zone by measurements of the Radiocaesium Interception Potential (RIP) in fertilized (RIP > 179 meq/kg) and non-fertilized soils (RIP < 74 meq/kg).  相似文献   

6.
This study proposes and empirically tests a framework that integrates the concepts of community resilience and social–ecological system (SES) resilience through community forestry case studies. The framework provides a possible approach for assessing community resilience based on the development and allocation of socio-cultural, economic, and natural capital of individual households within a given forest community. Furthermore, aspects of SES resilience and system dynamics are used to define the potential state thresholds of community resilience. This exploratory attempt to quantify community resilience, using the proposed framework, aims to advance understanding of the conceptual overlaps of SES and community resilience as applied to forestry management. We consider community forestry groups as SES examples in which the community is an important stakeholder in managing natural forest capital. We selected pioneer communities under the community-based forest management (CBFM) Program in the Philippines as our case studies. We found that, on average, CBFM group members demonstrated moderate levels of resilience according to their acquired levels of capital. Although economic capital remained the weakest capital, the CBFM program had a positive effect in increasing the socio-cultural and natural capital of an entire community.  相似文献   

7.
We summarize the patterns of 137Cs activity concentrations and transfer into fish and other biota in four small forest lakes in southern Finland during a twenty-year period following the Chernobyl accident in April 1986. The results from summer 1986 showed fastest accumulation of 137Cs into planktivorous fishes, i.e. along the shortest food chains. Since 1987, the highest annual mean values of 137Cs have been recorded in fish occupying the highest trophic levels, for perch (Perca fluviatilis) 13,600 Bq/kg (ww) and for pike (Esox lucius) 20,700 Bq/kg (ww). At the same time, activity concentrations of 137Cs in crustacean zooplankton and Asellus aquaticus have ranged between 1000 and 19,500 Bq/kg (dw). In 2006, 5-28% of the 1987 137Cs activity concentration levels were still present in perch and pike. Since 1989 their 137Cs activity concentrations in oligohumic seepage lakes have remained significantly higher than in polyhumic drainage lakes due to the increased transfer of 137Cs into fish in the seepage lakes with lower electrolyte concentrations, longer water retention times and lower sedimentation rate.  相似文献   

8.
Russian Journal of Ecology - Studies in the northern forest–tundra of Siberia have been performed to estimate temperature conditions in individual months of the growing season that have an...  相似文献   

9.
Forest fragmentation results in a loss of forest interior and an increase in edge habitat. As a result, these changes may affect the bird species distribution and composition. We studied how understorey bird community composition and habitat variables changed along an edge-to-interior gradient in a fragmented lowland rainforest in Peninsular Malaysia. Birds and environmental variables were recorded at each of the 93 sampling points distributed along the 14 parallel transects that were systematically placed across the gradient of distance from the forest edge to the forest interior. Species composition was different along the edge–interior gradient, although only a few species were strictly confined to either edge or interior habitat. Based on bird–habitat associations along the edge–interior gradient, some of these edge-preferred species occurred in high numbers at the matrix surrounding the patch. In contrast, the interior-specialist group, mainly terrestrial insectivores, avoided the forest edge and was positively associated with humidity, canopy cover, the number of dead trees, percentage of litter cover, and depth of the litter layer. Species endemic to the Sunda subregion were more abundant in the interior of the forest. From a conservation perspective, forest remnants in the lowlands of Peninsular Malaysia that have a deep leaf litter layer, dense canopy cover, high number of dead trees, and high relative humidity are able to support understorey bird species that are sensitive to edge effects. The forest has important conservation value even though it is fragmented and isolated.  相似文献   

10.
This paper explores China’s role in deforestation in Latin America. Brazil’s Amazon region contains vast natural resources including land, timber, minerals and hydroelectric potential. China’s strong economy and large demands relative to domestic supplies of these resources mean that China has become Brazil’s largest trading partner, primarily for natural resources. The paper examines how China influences deforestation in Brazilian Amazonia in a variety of ways, including through the direct influence of Chinese enterprises through land purchases and other mechanisms. This paper finds that the rapid rise in exports of soy and beef products to China are two of the major drivers of Amazonian deforestation in Brazil. The paper further argues that Chinese purchases of agricultural and forest land and Chinese imports of commodities such as timber and aluminum also cause environmental impacts in Amazonia. Chinese financing and investment in Amazonian infrastructure such as railways and mineral processing facilities have additional impacts.  相似文献   

11.
The horizontal distribution and quantitative characteristics of macrozoobenthos were studied in small lakes of the Darwin Nature Reserve (southern Vologda oblast). The aggregation index varied in the open areas of acid lakes, which indicated that communities of small acid water bodies were unstable. The aggregation was the lowest in the open area of a neutral lake. In acid lakes, the number and biomass of macroinvertebrates were the highest near the coasts. In the neutral lake, conversely, these values were maximum in open areas and low near the coast due to a strong pressure of predatory invertebrates and fish. An aggregating effect of invertebrate predators was observed near the coasts of lakes of different types.  相似文献   

12.
Monthly anomalies of stormy wind–wave heights and return periods are evaluated using secular routine observations in the coastal zone of the northern Black Sea. It is shown that wind–wave anomalies in this region are characterized by high-amplitude quasi-periodical variability with typical timescale of about 50 years. This timescale is determined by temporal variability of the coupled ocean–atmosphere system and coincides with periodicity of Atlantic Multidecadal Oscillation. Atmospheric re-analysis data show that cyclonic activity over the Black Sea basin intensifies when North Atlantic is relatively cold and meridional forms of atmospheric circulation are more frequent in the North Atlantic-Eurasian region. This leads to generation of more frequent Black Sea storm events and enhanced recurrence of extreme waves and results in profound (and mostly negative) environmental consequences. When North Atlantic is relatively warm and meridional forms of atmospheric circulation are less frequent in the North Atlantic-Eurasian region, environmental conditions in the Black Sea region are calmer. Thus, statistics of dangerous events can be wrongly estimated even if relatively long-term (~30 years) time series are considered and interdecadal variability of wind–wave anomalies must be taken into account when the risk assessment is accomplished.  相似文献   

13.
A quantitative survey of 1,377 households in three war-affected coastal districts of Jaffna, Mannar and Trincomalee in the north and east of Sri Lanka shows that inflation or price hikes, specially fuel, and natural disasters such as floods and droughts are highlighted as the shocks with the biggest impacts on fisher and non-fisher households. We hypothesise that the pattern/severity of households’ coping strategies to face these shocks depends on a set of household characteristics: livelihood diversity, asset ownership, level of education and the ability to borrow. Livelihood diversity, asset ownership and borrowings correlate significantly with the severity of coping strategies adopted by households for both fisher and non-fisher households. Education and livelihood diversification does not show a significant correlation for fisher households although it significantly affects livelihood diversification of both types of households.  相似文献   

14.
ObjectiveA recent longitudinal study reported an association between fine particulate (PM2.5) exposure and preterm birth (PTB) in a US cohort. We applied the same design to an Australian cohort to investigate associations with PTB and pre-labor rupture of membranes (PROM).MethodsFrom 287,680 births, we selected 39,189 women who had singleton births at least twice in Western Australia in 1997–2007 (n = 86,844 births). Analyses matched pregnancies to the same women with conditional logistic regression.ResultsFor PROM adjusted odds ratios (ORs) for a 1 μg/m3 increase in PM2.5 in the first trimester, second trimester, third trimester, and whole pregnancy were 1.00 (95% confidence interval (CI): 0.97, 1.03), 1.03 (95% CI: 1.00, 1.06), 1.02 (95% CI: 1.00, 1.05), and 1.02 (95% CI: 0.99, 1.05) respectively. For PTB, corresponding ORs were 1.00 (95% CI: 0.96, 1.04), 1.00 (95% CI: 0.96, 1.04), 0.98 (95% CI: 0.94, 1.02), and 0.99 (95% CI: 0.95, 1.04) respectively.ConclusionRisk of PROM was greater for pregnancies with elevated PM2.5 exposure in the second trimester than were other pregnancies to the same Australian women at lower exposure. There was insufficient evidence for an association with PTB, indicating that a longer time period might be needed to observe an association if a causal effect exists.  相似文献   

15.
Snow cover in Spanish mountains is crucial for ensuring water availability in spring and summer months, for the success of winter tourism or for the maintenance of biodiversity in mountain ecosystems. A changing climate may affect the volume of snow cover even in high mountains, where weather conditions are usually favorable for snow accumulation. In this paper, we aim to investigate the evolution (1970–2007) of combined precipitation–temperature modes in the Spanish mountains, and the sensitivity of the snowpack to their occurrence. The climatic database “Spain02” and snow thickness data for Spanish mountains were used for this purpose. Results showed that the frequency of dry-warm and wet-warm days has increased over time in all mountain ranges, while the frequency of the “cold” modes has decreased. The thickness of the snowpack in the Pyrenees has also decreased and its evolution is negatively correlated with the frequency of dry-warm days, and positively correlated with the frequency of dry-cold and wet-cold days. This work constitutes the first approach that relates the evolution of climatic conditions favorable or unfavorable for snow accumulation and the evolution of the snowpack in Spanish mountains.  相似文献   

16.
17.
Shifting cultivation around the Calakmul Biosphere Reserve of Mexico, part of the Mesoamerican Biological Corridor, appears to be intensifying temporally through reductions in crop–fallow cycles, with potential impacts on species diversity in the regenerating forest patches surrounding the reserve. This paper documents the temporal intensity of shifting maize cultivation in the region and links it to the species diversity found in secondary vegetation of different ages following different crop–fallow cycles. It finds that younger secondary growth, which is increasing under intensification, has less diversity in species composition. Simultaneously, the concentration of cultivation practices appears to foster more patches in older and more species-diverse vegetation. The implications for the preservation of the region’s forest remain uncertain, however, given the spatial concentration of open lands along two key axes, one which dissects the reserve.  相似文献   

18.
Two plants, a fern (Athyrium filix-femina) and a moss (Polytrichum commune Hedw.), both commonly occurring in Northern Temperate forests, were exposed in a laboratory study to a solution of (36)Cl-chloride. The uptake of (36)Cl-chloride by the plants was investigated and the emission of volatile chlorine 36 by the plants was determined. Furthermore, speciation of the emitted volatile organochlorine compounds (VOCls) was investigated. For the fern and the moss a rapid uptake of (36)Cl-chloride was observed within a 1-h exposure period. The uptake rates for the fern and the moss, respectively, were 16 mug (36)Cl-chloride g(-1) fresh weight (FW) h(-1) and 3.0 mug (36)Cl-chloride g(-1) FW h(-1), respectively. The study also suggested that after uptake by the plants (36)Cl-chloride is incorporated into VOCls, which were emitted by the plants into the atmosphere. Speciation analysis of the VOCls revealed the emission of chloroform, tetrachloromethane and 1,1,1-trichloroethane.  相似文献   

19.
This paper aims at identifying the link between significant rainfall decreases (1950–2000) in the Mediterranean basin and the atmospheric circulation at the 500 hPa level. The months and seasons of the subregions with significant rainfall decrease during this period have been identified previously (Norrant and Douguédroit, Theor Appl Climatol 83(1–4):89–106, 2006): October in the Mediterranean Iberia, March in the Atlantic Iberia, January and winter in Greece, and winter in the Near East. Canonical Correlation Analyses based on the monthly and daily data records from 62 rainfall stations and 138 grid points at the 500 hPa level over a Euro-Atlantic window were first calculated to define the TeleConnection Patterns explaining significant regional rainfall decreases. Then, 500 hPa level weather types (ZWTs) of the rainy days with important or little rainfall associated with each Teleconnection Pattern were identified in each subregion. Rainfall-causing disturbances from the Atlantic reach Iberia directly; some of them are regenerated if they reach the Mediterranean. Other disturbances are generated locally near Greece and the Near East (Meteorological Office in Weather in the Mediterranean I: general meteorology, Her Majesty’s Stationery Office, London, 1962). The relationship between significant rainfall decreases and the corresponding 500 hPa level appears to be a nonlinear phenomenon. In all of the studied subregions, a break during the 1970s separates two subperiods differing significantly from each other. Rainfall decrease is due to the higher frequency of important rainfall ZWTs over low rainfall ZWTs, during the first period, which the opposite is true during the second period. Such an inversion could be partially linked with the prevailing North Atlantic Oscillation-positive phase during the last quarter of the twentieth century.  相似文献   

20.
The relationship between human beings and forests has been important for the development of society. It is based on various productive, ecological, social and cultural functions of forests. The cultural functions, including the spiritual and symbolic role of forests, are often not addressed with the same attention as the other functions. The aim of this paper is to put a stronger emphasis on the fact that the acknowledgement of cultural bonds is needed in the discussion of sustainable development. Forest should not only be considered as a technical means to solve environmental and economic problems. To achieve a deeper understanding of the dependency of society on forests, it is necessary to recognise the role of forests in our consciousness of being human. Giving a historical overview about the cultural bonds between people and forests, the first part of the paper puts focus on non-productive aspects in human–forest relationships. Through history, forest values have changed and new functions have emerged. Industrialisation and urbanisation have contributed to an alienation from nature and weakened the connection of humans to forests. The consequences of these changes for the development of society and its environment are discussed in the second part of the paper. Finally, it is elaborated how the awareness of the cultural bonds can be strengthened in the population and especially in forest management; a management which should relate to cultural, emotional and aesthetical aspects, in addition to economic, ecological and social functions, and lead towards a sustainable relationship between forests and society.  相似文献   

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