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451.
Monitoring the dynamics of vegetation growth and its response to climate change is important to understand the mechanisms underlying ecosystem behaviors. This study investigated the relationship between vegetation growth and climate change during the growing seasons on the Loess Plateau in China by analyzing the normalized difference vegetation index (NDVI) derived from the Land Long Term Data Record dataset from 1982 to 2011. Results showed that growing-season NDVI had increased at an annual rate of 0.0028, particularly in the semi-arid and semi-humid regions. By contrast, the NDVI first increased from 1982 to 1994 (0.0013 year?1, P < 0.05) and then decreased from 1994 to 2011 (0.0016 year?1, P < 0.05) in the arid region. Temperature had a positive effect on NDVI in most periods within and across seasons in the semi-humid region but had no significant effect in the arid region. Precipitation had a positive effect on NDVI in the arid region in summer and in the semi-arid region in autumn. Summer precipitation was important for autumn vegetation growth in the arid region, whereas summer temperature increased autumn vegetation growth in the semi-arid and semi-humid regions. Further analyses supported the lag-time effects of climate change on vegetation growth on the Loess Plateau. Precipitation shifts had 15- to 18-month time lag effects on vegetation growth in the three climate regions. Vegetation NDVI had a 17-month lag response to temperature in the semi-arid region. Human activities should not be neglected in analyzing the relationship between vegetation growth and climate change on the Loess Plateau.  相似文献   
452.
Massanjore reservoir (area ~67 km2) located 84 km downstream from the most distant upstream source capacitates 620,000,000 m3 of water, and regulated flow characters are highly responsible for dam downstream alteration of hydrological, sedimentological and geomorphological characteristics of Mayurakshi River. In dam after condition, monsoon water level (mean water level during monsoon months) and pre-monsoon water level (mean water level during pre-monsoon months, i.e., March–May) have attenuated about 0.56 and 0.32 m, respectively. Maximum duration of high flow period during monsoon has reduced up to 16.5 %; coefficient of variation of diurnal fluctuation of water level during monsoon has increased from 31 to 47 %. Suspended sediment load in Mayurakshi River is reduced to 34 % in dam after period as recorded at Narayanpur gauge station. Average suspended sediment load has decreased even after Tilpara barrage construction from 4.960 to 4.350 mg/L. Average suspended sediment load is 7.875 mg/L in the sites of dam upstream course, and this average is only 4.46 mg/L in different sites of dam downstream course. Volume of discharge has decreased up to 11.3 % during monsoon time in dam after condition. Such reduction in discharge volume in turn has reduced about 24.6 % bed load-carrying capacity. As a result, huge deposition within channel invigorated channel bed aggradations (average 73.6 cm up to Saspara, site 14 at Fig. 1) in dam after condition. Narrowing of active channel, coarsening of channel bed materials, lowering of lateral stability, accelerating rise of braiding index, mixed response of the channel adjustment of the tributaries to local scale positive or negative base level change due to river bed aggradations and degradation, etc. signify the morphological alteration of dam downstream course.
Fig. 1 Mayurakshi River basin indicating Massanjore Dam, Tilpara barrage and sample working sites
  相似文献   
453.
On-farm tree cultivation is considered an important strategy to mitigate detrimental environmental impacts of agricultural land-use change (ALUC). In South Africa, however, little is known about farm-level incentives and constraints that govern ALUC decisions among small-scale farmers. To address this knowledge gap, this study employs a mixed multinomial logit model by using a combination of revealed and stated preference data. After correcting for endogeneity, the estimated results show that decisions about ALUC are rationally derived and driven by clear but heterogeneous preferences and trade-offs between crop productivity, food security and labour saving. The results further show that the decision to plant sugarcane is constrained by landholding, whilst farmland afforestation is negatively influenced by household size. Decisions to convert land use are also driven by the behaviour of peer groups and agro-ecological conditions. Based on these findings, important policy implications for sustainable land use are outlined.  相似文献   
454.
This two-part study investigates household preferences and willingness to pay (WTP) for water quality improvement of the Swat River in Pakistan. First, a four-point Likert scale was used to rank preferences for water quality benefits without using any financial metric. Results show that households have comparatively strong preferences for non-use benefits. Second, a contingent valuation question was designed to determine WTP for adopting a management plan developed exclusively for water quality improvement in the Swat River. The estimated annual mean WTP per household for water quality improvement is $2.40 when donating to an NGO. Generalizing this value to households living in Swat Valley would generate up to $544,000 per year. The present value aggregate benefit for 15 years would be sufficient to cover the present value of aggregate costs to adopt the management plan. A mandatory program that would require paying for the management plan generates half the WTP compared to the voluntary plan, but is still sufficient to cover costs and may be more feasible than a voluntary program because payment is assured.  相似文献   
455.
By 2050 most seafood will be sourced through aquaculture, with a range of production intensities being required to sustain livelihoods and to meet future needs from seafood. This makes Vietnam a particularly insightful case, since Vietnam is at the forefront of the trend toward greater aquaculture production. Our aim in this paper is to examine the social-ecological sustainability of small producer livelihoods contributing to Vietnam’s seafood boom. This paper uses original survey data to understand the range of fishery-based livelihoods that have contributed to Vietnam being a leading global exporter of seafood. We investigate the kinds of fishery-based livelihood activities that households are engaged in, consider the type and amount (kilograms) of species caught or farmed annually, and examine household perceptions’ of change in species quantity. We find that Vietnam’s seafood sector is facing real sustainability challenges: Nearly 30 % of small producers—fishers and fish farmers—within our sample rest at or below Vietnam’s rural poverty line. Ecological decline and disease in farmed fish is perceived to be a serious issue for all fishers. In this context, policy and management interventions need to better reflect social and ecological variability, adopt an integrated coastal systems perspective across fisheries and aquaculture, and consider the most impact-effective poverty interventions.  相似文献   
456.
This study analyzes the sources of income inequality among ethnic minorities in the Northwest region—the poorest and highest inequality region of Vietnam. Using an analysis of Gini decomposition by income source, the results show that while agricultural income, notably crop income, considerably decreases income inequality, off-farm income sources (wage and non-farm self-employment incomes) are found to increase inequality. This can be explained that in comparison with other income sources, agricultural income is more equally distributed and the main income source for most poor households. However, off-farm income sources are more unequally distributed and flow disproportionately toward the better-off. The findings support the hypothesis that income diversification in non-farm activities results in either greater inequality if opportunities for these activities are skewed toward to the better-off or less inequality if such opportunities are accessible to the poorer part of the population.  相似文献   
457.
Relationships between stem diameter and phytomass of trees and their parts (single- and multistemmed growth forms) have been studied at different altitudinal levels of the present-day upper treeline ecotone on the Iremel’ Massif, the Southern Urals. The time course of changes in the structure and phytomass of birch–spruce stands during the past centuries has been reconstructed. It is shown that the expansion of forests to the mountains in this period has occurred against the background of rise in summer and winter temperatures and increase in the amount of solid precipitation in the Southern Urals.  相似文献   
458.
The probable source of stone moroko, Pseudorasbora parva (Temminck & Schlegel, 1846), populations in lake- and stream-type Dnieper reservoirs was revealed. The dynamics and specific growth rates of these populations over 20 years were analyzed. The dynamic phase portrait method was used to determine the timing of stages in the process of invader naturalization and the periods when its populations were in equilibrium. The potential growth rates of P. parva populations in the Kremenchug and Dneprodzerzhinsk reservoirs were estimated.  相似文献   
459.
Deforestation and oil palm expansion in Central Kalimantan province are among the highest in Indonesia. This study examines the physical and monetary impacts of oil palm expansion in Central Kalimantan up to 2025 under three policy scenarios. Our modelling approach combines a spatial logistic regression model with a set of rules governing land use change as a function of the policy scenario. Our physical and monetary analyses include palm oil expansion and five other ecosystem services: timber, rattan, paddy rice, carbon sequestration, and orangutan habitat (the last service is analysed in physical units only). In monetary terms, our analysis comprises the contribution of land and ecosystems to economic production, as measured according to the valuation approach of the System of National Accounts. We focus our analysis on government-owned land which covers around 97 % of the province, where the main policy issues are. We show that, in the business-as-usual scenario, the societal costs of carbon emissions and the loss of other ecosystem services far exceed the benefits from increased oil palm production. This is, in particular, related to the conversion of peatlands. We also show that, for Central Kalimantan, the moratorium scenario, which is modelled based on the moratorium currently in place in Indonesia, generates important economic benefits compared to the business-as-usual scenario. In the moratorium scenario, however, there is still conversion of forest to plantation and associated loss of ecosystem services. We developed an alternative, sustainable production scenario based on an ecosystem services approach and show that this policy scenario leads to higher net social benefits including some more space for oil palm expansion.  相似文献   
460.
The concept of ecosystem services (ES) is being increasingly applied in environmental governance and science. To safeguard key ES in changing and complex social–ecological systems such as treeline areas, we need to (1) map key ES in different types of treeline landscapes, (2) identify the stakeholders benefiting from and threatening ES, and (3) examine how ES could be governed more sustainably. We explore these questions in European treeline areas by using quantitative and qualitative social science techniques to analyse responses from a survey of local scientific experts in 20 altitudinal and polar treeline areas in 15 European countries. In contrast to the prevalent consideration of treeline areas as a single type of a social–ecological system, we show that European treeline areas can be divided into two types that significantly differ in the delivery of ES. Our analyses allowed us to categorize stakeholders according to their benefits from and threats to ES; “Green key players” formed the most numerous group, while smaller number of stakeholder groups was categorized as “Harmless crowd”, “Occasional stressors”, and “Risky users”. However, behaviour of stakeholders is very much site-specific. Of 595 pairs of stakeholders analysed, we found <5 EU-wide “Allies” and “Opponents”. Recommendations for improved governance include adjusting governance instruments to specific problems in divergent treeline systems and creating participatory structures where stakeholders better interact with scientists and can genuinely influence management decisions.  相似文献   
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