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排序方式: 共有539条查询结果,搜索用时 15 毫秒
1.
Tsyplenkov Anatoly Vanmaercke Matthias Golosov Valentin Chalov Sergey 《Journal of Soils and Sediments》2020,20(8):3266-3281
Journal of Soils and Sediments - The sediment dynamics of (peri-)glacial catchments can be highly variable and complex. Understanding these dynamics and their underlying causes is not only of... 相似文献
2.
A change in the European Union energy policy has markedly promoted the expansion of biogas production.Consequently,large amounts of nutrient-rich residues are being used as organic fertilizers.In this study,a pot experiment was conducted to simulate the high-risk situation of enhanced greenhouse gas (GHG) emissions following organic fertilizer application in energy maize cultivation.We hypothesized that cattle slurry application enhanced CO2 and N2O fluxes compared to biogas digestate because of the overall higher carbon (C) and nitrogen (N) input,and that higher levels of CO2 and N2O emissions could be expected by increasing soil organic C (SOC) and N contents.Biogas digestate and cattle slurry,at a rate of 150 kg NH4+-N ha-1,were incorporated into 3 soil types with low,medium,and high SOC contents (Cambisol,Mollic Gleysol,and Sapric Histosol,termed Clow,Cmedium,and Chigh,respectively).The GHG exchange (CO2,CH4,and N2O) was measured on 5 replicates over a period of 22 d using the closed chamber technique.The application of cattle slurry resulted in significantly higher CO2 and N2O fluxes compared to the application of biogas digestate.No differences were observed in CH4 exchange,which was close to zero for all treatments.Significantly higher CO2 emissions were observed in Chigh compared to the other two soil types,whereas the highest N2O emissions were observed in Cmedium.Thus,the results demonstrate the importance of soil type-adapted fertilization with respect to changing soil physical and environmental conditions. 相似文献
3.
The effects of weaning on beef calves of different ages were investigated. Forty male and 40 female calves were either weaned at 6 (W6, n = 40) or 8 (W8, n = 40) months of age. The vocalization activity and behaviors (feeding, lying and standing/walking) were observed during the first 3 days following weaning. Body weight was recorded at 6 and 8 months and 2 weeks following weaning. W6 animals vocalized more often than W8 calves and females more than males on day 1 (P < 0.05). The vocalization activity decreased at a higher rate in W8 than in W6 from days 1 to 3. On day 2, W6 calves spent less time lying and more standing/walking than W8 calves (P < 0.05). The behaviors did not differ between males and females. The average daily gain after weaning did not differ between weaning ages (P > 0.05), but W8 calves gained more from 6 to 8 months of age. In conclusion, weaning distress was more pronounced in W6 than in W8 calves. W8 calves also had a superior growth performance during 6 to 8 months of age. The effect of the calves' sex was less pronounced. Therefore, it is recommended to wean beef calves later than 6 months of age. 相似文献
4.
Maria Garcia-Martin Nora Fagerholm Claudia Bieling Dimitris Gounaridis Thanasis Kizos Anu Printsmann Matthias Müller Juraj Lieskovský Tobias Plieninger 《Landscape Ecology》2017,32(11):2133-2150
Context
Human–nature interactions are reflected in the values people assign to landscapes. These values shape our understanding and actions as landscape co-creators, and need to be taken into account to achieve an integrated management of the landscape that involves civil society.Objectives
The aim of this research was to increase the current knowledge on the most and least common landscape values perceived by local stakeholders, the patterns in the spatial distribution of values, and their connection to different socio-economic backgrounds and landscape characteristics across Europe.Methods
The research consisted of a cross-site comparison study on how landscape values are perceived in six areas of Europe using Public Participation GIS surveys. Answers were analysed combining contingency tables, spatial autocorrelation and bivariate correlation methods, kernel densities, land cover ratios, and viewshed analyses. Results were discussed in the light of findings derived from other European participatory mapping studies.Results
We identified shared patterns in the perception of landscape values across Europe. Recreation, aesthetics, and social fulfilment were the most common values. Landscape values showed common spatial patterns mainly related to accessibility and the presence of water, settlements, and cultural heritage. However, respondents in each study site had their own preferences connected to the intrinsic characteristics of the local landscape and culture.Conclusions
The results encourage land planners and researchers to approach landscape values in relation to socio-cultural and bio-physical land characteristics comprehensibly, acknowledging the complexity in the relationship between people’s perception and the landscape, to foster more effective and inclusive landscape management strategies.5.
Landscape Ecology - Landscape archaeology has a lot to offer to landscape ecology, being an interdisciplinary approach that emphasizes the study of long-term human–environment dynamics. We... 相似文献
6.
Tappeiner Ulrike Leitinger Georg Zariņa Anita Bürgi Matthias 《Landscape Ecology》2021,36(8):2317-2328
Landscape Ecology - Landscape ecology early on developed the awareness that central objects of investigation are not stable over time and therefore the historical dimension must be included, or at... 相似文献
7.
In Central Europe vast wetland areas have been converted into agricultural land over the past few centuries. Long-term spatially
explicit reconstructions of wetland cover changes at regional scale are rare but such information is vital for setting appropriate
wetland conservation and restoration goals. In this study wetland cover change over the past 150 years was analyzed for the
Canton Zurich (Switzerland) using information from historical and current topographical maps. Mapping instructions changed
significantly over time, i.e., wetlands were mapped more conservatively on older maps. Therefore a technique was developed
to account for changes in mapping instructions and to reconstruct a series of comparable maps spanning 1850–2000. Wetland
cover dramatically decreased from 13,759 ha in 1850 (more than 8% of the total study area) to 1,233 ha in 2000 (less than
1%). Largest loss is observed for the first half of the twentieth century when more than 50% of the total wetland loss occurred.
In 1850, almost all wetland patches were connected in two large networks defined by a 500 m buffer around all wetland patches
to account for typical dispersal distances of wetland animals. Despite extensive wetland loss, this networks remained largely
intact until 1950, but then collapsed into many medium and small networks consisting of only few wetland patches. In addition
to the direct loss of wetland habitats increased habitat fragmentation is limiting metapopulation dynamics and hindering genetic
exchange between populations. Amphibians and other wetland animals are particularly prone to habitat fragmentation because
of their limited migration abilities. This may lead to time-delayed extinction in the future because current species occurrence
might rather reflect historical than current wetland cover and habitat configuration. Future restoration efforts should focus
on reestablishing connectivity between remaining smaller wetland networks. 相似文献
8.
Turbulent fluxes of carbon, water and energy were measured at the Wind River Canopy Crane, Washington, USA from 1999 to 2004 with eddy-covariance instrumentation above (67 m) and below (2.5 m) the forest canopy. Here we present the decomposition of net ecosystem exchange of carbon (NEE) into gross primary productivity (GPP), ecosystem respiration (R(eco)) and tree canopy net CO(2) exchange (DeltaC) for an old-growth Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco)-western hemlock (Tsuga heterophylla (Raf.) Sarg.) forest. Significant amounts of carbon were recycled within the canopy because carbon flux measured at the below-canopy level was always upward. Maximum fluxes reached 4-6 micromol m(-2) s(-1) of CO(2) into the canopy air space during the summer months, often equaling the net downward fluxes measured at the above-canopy level. Ecosystem respiration rates deviated from the expected exponential relationship with temperature during the summer months. An empirical ecosystem stress term was derived from soil water content and understory flux data and was added to the R(eco) model to account for attenuated respiration during the summer drought. This attenuation term was not needed in 1999, a wet La Ni?a year. Years in which climate approximated the historical mean, were within the normal range in both NEE and R(eco), but enhanced or suppressed R(eco) had a significant influence on the carbon balance of the entire stand. In years with low respiration the forest acts as a strong carbon sink (-217 g C m(-2) year(-1)), whereas years in which respiration is high can turn the ecosystem into a weak to moderate carbon source (+100 g C m(-2) year(-1)). 相似文献
9.
Field-grown poplar trees (Populus nigra L. x P. maximowiczii Henry, clone Kamabuchi) were exposed to severe drought twice during the growing season to evaluate the impact on wood cell development. The drought treatment caused a reduction in leaf water potential, leaf wilting and a decreased concentration of osmotically active solutes in the cambial zone. Drought-induced changes in the anatomy of developing xylem cells were examined in stem sections and macerated wood samples. In early summer, drought significantly reduced the length and cross-sectional area of newly formed fibers, whereas no such effects were observed in late summer. In well-watered trees, fiber cross-sectional area declined between early and late summer. Similarly, drought reduced the cross-sectional area of vessel elements in early summer but not in late summer, whereas in both control and drought-treated trees, the cross-sectional area of vessel elements decreased between early and late summer. The vessel area to xylem area ratio was unaffected by drought because the drought-induced decrease in vessel size was matched by an increase in the number of newly formed vessel cells. In contrast to its effect in early summer, late-summer drought had no significant effect on fiber and vessel cell development, indicating that sensitivity of wood cell development to drought varies seasonally. 相似文献
10.
Matthias Schmidt Andres Kiviste Klaus von Gadow 《European Journal of Forest Research》2011,130(2):303-315
This contribution presents an approach to model individual tree height?Cdiameter relationships for Scots pine (Pinus sylvestris) in multi-size and mixed-species stands in Estonia using the Estonian Permanent Forest Research Plot Network. The dataset includes 22,347 trees. The main focus of the study was to use an approach that is spatially explicit allowing for high accuracy prediction from a minimum set of predictor variables that can be easily derived. Consequently, the height?Cdiameter relationship is modeled as a function of only the stand quadratic mean diameter (dg) and the plot geographical coordinates. A specific generalized additive model gam is employed that allows for the integration of a varying coefficient term and 2-dimensional surface estimators representing a spatial trend and a spatially varying coefficient term. The high flexibility of the model is needed due to the very few predictor variables that subsume a variety of potential influential factors. Subsequently, a linear mixed model is used that quantifies the random variation between plots and between measurement occasions within plots, respectively. Hence, our model is based on the theory of structured additive regression models (Fahrmeir et al. 2007) and separates a structured (correlated) spatial effect from an unstructured (uncorrelated) spatial effect. Additionally, the linear mixed model allows for calibration of the model using height measurements as pre-information. Model bias is small, despite the somewhat irregular distribution of experimental areas within the country. The overall model shows some similarity with earlier applications in Finland. However, there are important differences involving the model form, the predictors and the method of parameter estimation. 相似文献