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71.
A series of lab and greenhouse studies were undertaken to understand how Cu and Zn toxicity influences Bromus carinatus (Hook and Arn.) growth, to what degree an organic amendment (yard waste compost) may reduce Cu and Zn bioavailability in Cu-Zn minespoil and promote plant growth in combination with fertilizer, and how the vertical distribution of compost in the minespoil influences rooting depth. Root Cu and Zn toxicity thresholds were determined to be 1 mgL(-1) and 10 mgL(-1) in solution, respectively. The compost amendment had exceptionally high Cu and Zn binding capacities (0.17 and 0.08 g metal g C(-1), for Cu and Zn, respectively) that were attributed to high compost humic and fulvic acid concentrations. Maximum plant biomass was achieved when minespoil was amended with compost and fertilizer in combination. Fertilizer alone had no effect on plant growth. Mixing compost into the minespoil was essential to promote adequate rooting depth.  相似文献   
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What supports the adaptive capacity of watershed governance? Using document review, interviews, and network diagrams, we analyze how structural attributes of a governance network emerged and co-evolved with changes in biophysical conditions in a case study of a small watershed in northeast Ohio. Results indicate that the network governance structure that emerged evolved to become a hybrid of two different structural forms that diversified stakeholder engagement, generated social capital, improved social learning, and stimulated change in management practices, all of which have enhanced adaptive capacity. A significant challenge to adaptive capacity arises, however, as network governance has come to rely significantly on a centralized organization to broker relationships for information and other resources.  相似文献   
74.
Conservation practices are implemented on farm fields in the USA through Farm Bill programs; however, there is a need for greater verification that these practices provide environmental benefits (e.g., water quality). This study was conducted to assess the impact of Farm Bill eligible conservation practices on soluble P (SP) and total P (TP) losses from four fields that were monitored between 2004 and 2013. No-tillage doubled SP loading compared to rotational tillage (e.g., tilled only before planting corn); however, no-tillage decreased TP loading by 69 % compared to rotational tillage. Similarly, grassed waterways were shown to increase SP loads, but not TP loads. A corn–soybean–wheat–oat rotation reduced SP loads by 85 % and TP loads by 83 % compared to the standard corn–soybean rotation in the region. We can potentially attain TP water quality goals using these Farm Bill practices; however, additional strategies must be employed to meet these goals for SP.  相似文献   
75.
Like the rest of the world, African countries are reeling from the health, economic and social effects of COVID-19. The continent’s governments have responded by imposing rigorous lockdowns to limit the spread of the virus. The various lockdown measures are undermining food security, because stay at home orders have among others, threatened food production for a continent that relies heavily on agriculture as the bedrock of the economy. This article draws on quantitative data collected by the GeoPoll, and, from these data, assesses the effect of concern about the local spread and economic impact of COVID-19 on food worries. Qualitative data comprising 12 countries south of the Sahara reveal that lockdowns have created anxiety over food security as a health, economic and human rights/well-being issue. By applying a probit model, we find that concern about the local spread of COVID-19 and economic impact of the virus increases the probability of food worries. Governments have responded with various efforts to support the neediest. By evaluating the various policies rolled out we advocate for a feminist economics approach that necessitates greater use of data analytics to predict the likely impacts of intended regulatory relief responses during the recovery process and post-COVID-19.  相似文献   
76.
The strategic importance of ecosystem service valuation as an operational basis for policy decisions on natural restoration has been increasingly recognized in order to align the provision of ecosystem services with the expectation of human society. The contingent valuation method (CVM) is widely used to quantify various ecosystem services. However, two areas of concern arise: (1) whether people value specific functional ecosystem services and overlook some intrinsic aspects of natural restoration, and (2) whether people understand the temporal dimension of ecosystem services and payment schedules given in the contingent scenarios. Using a peri-urban riparian meadow restoration project in Flanders, Belgium as a case, we explored the impacts of residents’ perceived importance of various ecosystem services and stated financial constraints on their willingness-to-pay for the proposed restoration project employing the CVM. The results indicated that people tended to value all the benefits of riparian ecosystem restoration concurrently, although they accorded different importances to each individual category of ecosystem services. A longer payment scheme can help the respondents to think more about the flow of ecosystem services into future generations. A weak temporal embedding effect can be detected, which might be attributed to respondents’ concern about current financial constraints, rather than financial bindings associated with their income and perceived future financial constraints. This demonstrates the multidimensionality of respondents’ financial concerns in CV. This study sheds light on refining future CV studies, especially with regard to public expectation of ecosystem services and the temporal dimension of ecosystem services and payment schedules.  相似文献   
77.
One commonly accepted mechanism for biological invasions is that species, after introduction to a new region, leave behind their natural enemies and therefore increase in distribution and abundance. However, which enemies are escaped remains unclear. Escape from specialist invertebrate herbivores has been examined in detail, but despite the profound effects of generalist herbivores in natural communities their potential to control invasive species is poorly understood. We carried out parallel laboratory feeding bioassays with generalist invertebrate herbivores from the native (Europe) and from the introduced (North America) range using native and nonnative tetraploid populations of the invasive spotted knapweed, Centaurea stoebe. We found that the growth of North American generalist herbivores was far lower when feeding on C. stoebe than the growth of European generalists. In contrast, North American and European generalists grew equally well on European and North American tetraploid C. stoebe plants, lending no support for an evolutionary change in resistance of North American tetraploid C. stoebe populations against generalist herbivores. These results suggest that biogeographical differences in the response of generalist herbivores to novel plant species have the potential to affect plant invasions.  相似文献   
78.
Norwegian Protected Landscapes aim to preserve landscape character. As most of the agricultural land in Protected Landscapes is privately owned, the attitudes and behaviour of farmers are crucial in achieving this goal. We present results of a nationwide questionnaire to farmers who owned or managed farmland in Protected Landscapes. Thirty-eight percent of the respondents claimed that their farm business had been changed as a consequence of landscape protection. Niche products and alternative income possibilities, commonly forwarded as potential benefits of landscape protection status, had generally not been realised. Although we found that most farmers agreed on the importance of taking care of cultural landscapes, 76% felt that this was best done by using rather than protecting the landscape. The study revealed negative attitudes towards municipal authorities. A quarter of respondents were strongly against the establishment of new Protected Landscapes, even if they were compensated for economic losses. Based on results of the study we suggest that major improvements to the protection system could be made by improving communication between management authorities and farmers, and ensuring real involvement of farmers in making and carrying out management plans.  相似文献   
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A large-scale database concerning benthic copepods from the Arctic, Baltic Sea, North Sea, British Isles, Adriatic Sea and Crete was compiled to assess species richness, biodiversity, communities, ecological range size and biogeographical patterns. The Adriatic showed the highest evenness and the most species-rich communities. Assemblages from the North Sea, British Isles, Baltic and Crete had a lower evenness. The British Isles were characterised by impoverished communities. The ecological specificity of copepod species showed two diverging trends: higher specificity of species in more diverse assemblages was observed in the Adriatic, North Sea and Baltic. A uniformly high species specificity disregarding sample diversity was found on Crete and in the British Isles. Benthic copepod communities showed distinct patterns that clearly fit the predefined geographical regions. Communities were distinguishable and β-diversity was found to be high around Europe, indicating a high species turnover on the scale of this investigation. The British Isles and the North Sea were found to be faunistic links to the Baltic and the Arctic.  相似文献   
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