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1.
P. M. S. Jayathilaka Peeyush Soni Sylvain R. Perret H. P. W. Jayasuriya Vilas M. Salokhe 《Regional Environmental Change》2012,12(1):55-68
Climate change is the main global challenge of this century; it is therefore imperative to identify its effects on agriculture
in developing countries. This research makes spatial assessment of climate change effect on major plantation crops in Sri
Lanka, with emphasis on crop suitability of tea, rubber, and coconut. Geo-referenced maps of spatial and temporal changes
in crop suitability and production potentials are generated and compared. Data pertaining to six agro-ecological zones under
the study area are analyzed for a period of 1980–2007. Crop suitability maps are generated amalgamating yield maps and climatic
factors maps using AHP in multi-criteria analysis under two time frames of 1980–1992 and 1993–2007. Percent change in crop
suitability and crop yield classes is calculated based on five crop suitability and five crop yield classes during two time
frames. Dynamics of climatic parameters and crop yield are recognized using geo-referenced maps. The suitability maps of the
two time frames are compared to identify the changes with each crop in conjunction with changes in the prevailing climate
and yield. Geographic shift of suitability, yield, and climate classes are examined. Net gain or loss in crop production is
quantified. Long-term annual rainfall significantly decreased in mid-country wet zone, whereas the mean temperature of the
study area increased by 1.4°C. Results clearly showed that the climate and yield can be meaningfully related to the crop suitability
and management. 相似文献
2.
Technical- and Environmental-Efficiency Analysis of Irrigated Cotton-Cropping Systems in Punjab,Pakistan Using Data Envelopment Analysis 总被引:1,自引:0,他引:1
Cotton cropping in Pakistan uses substantial quantities of resources and adversely affects the environment with pollutants from the inputs, particularly pesticides. A question remains regarding to what extent the reduction of such environmental impact is possible without compromising the farmers’ income. This paper investigates the environmental, technical, and economic performances of selected irrigated cotton-cropping systems in Punjab to quantify the sustainability of cotton farming and reveal options for improvement. Using mostly primary data, our study quantifies the technical, cost, and environmental efficiencies of different farm sizes. A set of indicators has been computed to reflect these three domains of efficiency using the data envelopment analysis technique. The results indicate that farmers are broadly environmentally inefficient; which primarily results from poor technical inefficiency. Based on an improved input mix, the average potential environmental impact reduction for small, medium, and large farms is 9, 13, and 11 %, respectively, without compromising the economic return. Moreover, the differences in technical, cost, and environmental efficiencies between small and medium and small and large farm sizes were statistically significant. The second-stage regression analysis identifies that the entire farm size significantly affects the efficiencies, whereas exposure to extension and training has positive effects, and the sowing methods significantly affect the technical and environmental efficiencies. Paradoxically, the formal education level is determined to affect the efficiencies negatively. This paper discusses policy interventions that can improve the technical efficiency to ultimately increase the environmental efficiency and reduce the farmers’ operating costs. 相似文献
3.
M. M. Lambrechts A. Rieux M. -J. Galan M. Cartan-Son P. Perret J. Blondel 《Russian Journal of Ecology》2008,39(7):516-522
Although mistimed reproduction (i.e., time-lag between peak food supply and offspring food demand) has been attributed to
habitat modifications or climate change in recent avian investigations, earlier breeding parents have higher reproductive
success in many habitats. Here we compare first and second broods in great tits (Parus major L.) from two Mediterranean oak habitats differing significantly in the timing (about 5 weeks), but not the amount of caterpillar
supply required to rear chicks. The study indicates that both the extent of mistimed reproduction and the breeding date per se influence breeding performance in this study system.
The text was submitted by the authors in English. 相似文献
4.
Environmental Fluid Mechanics - The characteristics of large- and small-scale turbulent motions at roof-level in a street canyon flow were experimentally investigated along with their... 相似文献
5.
Anne?CharmantierEmail author Philippe?Perret 《Behavioral ecology and sociobiology》2004,56(4):360-365
We tested the effect of manipulation of breeding density on the occurrence of extra-pair paternity in a blue tit (Parus caeruleus) population during two consecutive years. In a homogeneous oak forest, nest-box manipulation provided a high density plot (plot A, 1.10 and 1.32 pairs/ha) and a low density plot (plot B, 0.43 and 0.46 pairs/ha). Microsatellite analysis on 91 broods revealed a higher proportion of extra-pair paternity in broods in plot A (mean of 17.2%) than in plot B (mean of 11.4%). A correlative approach showed that the proportion of extra-pair young in broods was affected by the number of breeding neighbours within 100 m around the nest-box, by the distance to the nearest breeding neighbour and by an additional plot effect. However, the nearest neighbours accounted for only 39.3% of extra-pair paternities and distance to extra-pair fathers was significantly higher than the nearest neighbour distance in both plots. This implies that the effect of density on the occurrence of extra-pair paternities is associated with active female choice to enhance the brood fitness. Although there were more extra-pair young in broods when density was high, the number of extra-pair fathers did not increase and stayed close to one. We suggest that density increases the cost of mate guarding by males, thereby increasing the possibility for females to solicit extra-pair paternities to the cuckolding male they have chosen. Finally, we discuss why correlatives approaches do not always show evidence for an effect of breeding density on extra-pair paternity occurrence.Communicated by M. Soler 相似文献
6.
In Southeast Asia, inland fish resources are crucial for small-scale fishing households. Their decline, due to overfishing and a set of socio-ecological factors, jeopardises aquatic ecosystems and the livelihoods of fishing communities. Singkarak Lake (West Sumatra) exemplifies this sustainability challenge. The paper proposes a multi-disciplinary analysis of the situation. First, it identifies and documents the primary livelihood systems and the strategic adaptations involved in fishing communities. Based upon a sample of 200 households and the implementation of multivariate analyses, a typology is developed. Three household types are identified. Type I comprises better-off farming fishers that have high fishing capitals and income but the lowest returns on fishing and land assets. Type II includes poor fishing farmers with higher farming income; they show the highest return on land assets. Type III is composed of poorer, younger fishers with the highest return on fishing assets and fishing costs. They have little land, low farming income, and diversified livelihood sources. Second, the technical efficiency (TE) of fishing households is studied using a data envelopment analysis. The results show that the average TE is low, but marked differences exist between the types. Type I households have the lowest TE in fishing, confirming an extensification and overcapitalisation strategy. Type II households show a high technical fishing efficiency. They have developed on-farm diversification with a combined, balanced livelihood system. Type III households are the most efficient fishers. They developed an intensification strategy together with off-farm diversification. Different livelihood strategies and economic portfolio have been developed as the response to the limited resources, uncertainty, fluctuating environment and other source of vulnerability. The fishers built up their livelihood based on their assets’ ownership, access to other resource out of fishing and their socio-economic status. In this context, understanding livelihood diversity among small-scale fishers, different socio-economic, their efficiency, constraints and opportunities emerge as important factor in policy formulation to enhance support to small-scale fishing communities and improved management of both the resources and local development. Finally, the paper suggests a focus on people and community-related solutions and proposes a threefold approach of resource conservation, livelihood improvements and restructured governance. 相似文献
7.
Studying evolutionary mechanisms in natural populations often requires testing multifactorial scenarios of causality involving direct and indirect relationships among individual and environmental variables. It is also essential to account for the imperfect detection of individuals to provide unbiased demographic parameter estimates. To cope with these issues, we developed a new approach combining structural equation models with capture-recapture models (CR-SEM) that allows the investigation of competing hypotheses about individual and environmental variability observed in demographic parameters. We employ Markov chain Monte Carlo sampling in a Bayesian framework to (1) estimate model parameters, (2) implement a model selection procedure to evaluate competing hypotheses about causal mechanisms, and (3) assess the fit of models to data using posterior predictive checks. We illustrate the value of our approach using two case studies on wild bird populations. We first show that CR-SEM can be useful to quantify the action of selection on a set of phenotypic traits with an analysis of selection gradients on morphological traits in Common Blackbirds (Turdus merula). In a second case study on Blue Tits (Cyanistes caeruleus), we illustrate the use of CR-SEM to study evolutionary trade-offs in the wild, while accounting for varying environmental conditions. 相似文献
8.
Alice Rémy Arnaud Grégoire Philippe Perret Claire Doutrelant 《Behavioral ecology and sociobiology》2010,64(11):1839-1847
Badges of status, usually color patches, are hypothesized to serve as important signals within natural populations by communicating
an individual’s fighting ability or aggressiveness before an interaction ever takes place. These signals, which may evolve
via sexual and/or social selection, mediate intra-specific competition by influencing the outcome or escalation of contests
between individuals. The last 10 years saw the rise of interest in the role of ultraviolet (UV)-based coloration in intra-sexual
communication. However, the rare experimental studies that tested this hypothesis found opposite results, which may originate
from the different methodological procedures used to assess the badge of status theory. We present here the results of an
experiment testing whether male blue tits (Cyanistes caeruleus) respond differently to unfamiliar conspecifics presenting contrasted UV crest coloration. In an aviary, we simultaneously
presented two caged blue tits with enhanced (UV+) or reduced (UV−) crest coloration to a focal bird. We found that focal males
acted more aggressively towards the UV− males than UV+ males. In addition, focal males fed more often close to males that
were similar in brightness or duller than themselves. We conclude that, in blue tits, UV blue crest coloration affects both
social and aggressive responses towards unfamiliar individuals, and thus it has some properties of a badge of status. 相似文献
9.
Technical and socio-economic characteristics are known to determine different types of fishers and their livelihood strategies. Faced with declining fish and water resources, small-scale fisheries engage into transformations in livelihood and fishing practices. The paper is an attempt to understand these changes and their socio-economic patterns, in the case of Singkarak Lake in West Sumatra, Indonesia. Based upon the hypothesis that riparian communities have diverse, complex yet structured and dynamic livelihood systems, the paper’s main objective is to study, document and model the actual diversity in livelihood, practices and performance of inland small-scale fisheries along the Singkarak Lake, to picture how households are adapted to the situation, and propose an updated, workable model (typology) of those for policy. Principal component analysis and cluster analysis were used to develop a typology of fishing households. The results show that small-scale fishers can be classified into different types characterized by distinct livelihood strategies. Three household types are identified, namely “farming fishers” households (type I, 30 %), “fishing farmers” households (type II, 30 %), and “mainly fishers” households (type III, 40 %). There are significant differences among these groups in the number of boats owned, annual fishing income, agriculture income and farming experience. Type I consists of farming fishers, well equipped, with high fishing costs and income, yet with the lowest return on fishing assets. They are also landowners with farming income, showing the lowest return on land capital. Type II includes poor fishing farmers, landowners with higher farming income; they show the highest return on land asset. They have less fishing equipment, costs and income. Type III (mainly fishers) consists of poorer, younger fishers, with highest return on fishing assets and on fishing costs. They have little land, low farming income, and diversified livelihood sources. The nature of their livelihood strategies is discussed for each identified group. This helps to understand the complexity and diversity of small-scale fishers, particularly in the study area which is still poorly known. This paper concludes with policy implication and possible management initiatives for environmentally prudent policy aiming at improvement of fishers’ livelihood. 相似文献
10.
Adapting cropping systems to climate change in Nepal: a cross-regional study of farmers’ perception and practices 总被引:4,自引:1,他引:3
Sujata Manandhar Dietrich Schmidt Vogt Sylvain R. Perret Futaba Kazama 《Regional Environmental Change》2011,11(2):335-348
Climate change is a global challenge that has a particularly strong effect on developing countries such as Nepal, where adaptive
capacity is low and where agriculture, which is highly dependent on climatic factors, is the main source of income for the
majority of people. The nature and extent of the effects of climate change on rural livelihoods varies across Nepal in accordance
with its highly diverse environmental conditions. In order to capture some of this variability, a comparative study was performed
in two different ecological regions: Terai (lowland) and Mountain (upland) in the western development region of Nepal. The
study focuses on perceptions of, and on adaptations to climate change by farmers. Information was collected from both primary
and secondary data sources. Climate data were analyzed through trend analysis. Results show that most farmers perceive climate
change acutely and respond to it, based on their own indigenous knowledge and experiences, through both agricultural and non-agricultural
adaptations at an individual level. The study also shows that there is a need to go beyond the individual level, and to plan
and provide support for appropriate technologies and strategies in order to cope with the expected increasing impacts of climate
change. 相似文献