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Traditional Land-Use Systems and Patterns of Forest Fragmentation in the Highlands of Chiapas, Mexico 总被引:1,自引:0,他引:1
Ochoa-Gaona S 《Environmental management》2001,27(4):571-586
The influence of slash-and-burn agriculture and tree extraction on the spatial and temporal pattern of forest fragmentation
in two municipalities in the highlands of Chiapas, Mexico was analyzed. The data series were derived from two subsets of satellite
images taken in 1974 and 1996. The analysis was based on area, edge, shape, core area, and neighbor indices. During the 22
years, the dense forest decreased by 8.9%/yr in Huistán and by 8.6%/yr in Chanal, while open/disturbed forest, secondary vegetation,
and developed area increased in both municipalities. The total number of fragments increased by 1.4%/yr and 2.3%/yr in Huistán
and Chanal, respectively. Dense forest showed the highest increase in the number of fragments (6%/yr in Huistán and 12%/yr
in Chanal), while edge length, core area, and number of dense forest core areas decreased. The larger fragments of dense forest
present in 1974 were divided into smaller fragments in 1996; at the same time, they experienced a process of degradation toward
open/disturbed forest and secondary vegetation. Two different fragmentation patterns could be distinguished based on agricultural
or forestry activities. Forest fragmentation did not occur as a continuous process; the pattern and degree of fragmentation
were functions of land tenure, environmental conditions, and productive activities. The prevalence of rather poor soil conditions,
small-holdings, growing human population densities, increasing poverty, and the absence of alternative economic options will
maintain a high rate of deforestation and forest fragmentation in the studied region. 相似文献
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BEN H. J. DE JONG MICHAEL A. CAIRNS PATRICIA K. HAGGERTY NEPTALÍ RAMÍREZ-MARCIAL SUSANA OCHOA-GAONA JORGE MENDOZA-VEGA GONZÁLEZ-ESPINOSA IGNACIO MARCH-MIFSUT 《Environmental management》1999,23(3):373-385
6 tons C were released to the atmosphere during the period of time covered by our study, equal to approximately 34% of the
1975 vegetation C pool. The Chiapas highlands, while comprising just 0.3% of Mexico's surface area, contributed 3% of the
net national C emissions. 相似文献
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Optimization of the Resources Management in Fighting Wildfires 总被引:1,自引:0,他引:1
Wildfires lead to important economic, social, and environmental losses, especially in areas of Mediterranean climate where
they are of a high intensity and frequency. Over the past 30 years there has been a dramatic surge in the development and
use of fire spread models. However, given the chaotic nature of environmental systems, it is very difficult to develop real-time
fire-extinguishing models. This article proposes a method of optimizing the performance of wildfire fighting resources such
that losses are kept to a minimum. The optimization procedure includes discrete simulation algorithms and Bayesian optimization
methods for discrete and continuous problems (simulated annealing and Bayesian global optimization). Fast calculus algorithms
are applied to provide optimization outcomes in short periods of time such that the predictions of the model and the real
behavior of the fire, combat resources, and meteorological conditions are similar. In addition, adaptive algorithms take into
account the chaotic behavior of wildfire so that the system can be updated with data corresponding to the real situation to
obtain a new optimum solution. The application of this method to the Northwest Forest of Madrid (Spain) is also described.
This application allowed us to check that it is a helpful tool in the decision-making process. 相似文献
4.
Siar SV 《Environmental management》2003,31(5):0569-0580
The coastal zone is a place of intense activity where resources, users, and resource-use practices interact. This case study
of small-scale fisheries in Honda Bay, Palawan, Philippines shows that resources, space, and gender are intertwined. The study
was conducted between June 1997 and July 1998. The data were gathered using free listing, pile sort, ranking, resource mapping,
and key informant interviews. The results showed that women's knowledge about fishery resources and their fishing activities
are associated with the intertidal zone whereas men's knowledge is associated with coral reefs. In classifying fishery resources,
appearance is the main consideration for women whereas a combination of appearance, habitat, and type of fishing gear is the
consideration used by men. Market price is very important because of its dependence on the demand of the export market as
well as the local market. Women dominate the buying of fishery products. Many women market their husband's catch, process
fish, or gather shells and sea cucumber for sale. Among the fishing households, type of fishing gear provides an indication
of socioeconomic standing. This paper concludes that access to resources is shaped by gender and age. The differences in resource
knowledge possessed by men and women lead to differential access to fishery resources. In addition, the differences in socioeconomic
status also influence resource access. The socialization of children into fishing reinforces the gender division of labor
and space in the coastal zone. 相似文献
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