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1.
Forest-covered home gardens around the tropical world vary in their structure, but serve to supply food and other products for direct family consumption or marketing. Little quantitative data exist defining home garden structure. Thus, this study was undertaken to examine the variation in home garden structures in response to market or household needs and the subsequent variation in light interception and productivity.Four home gardens were studied in the Department of the Petén, in northern Guatemala. Areal extent and height of canopies were mapped in transects through four gardens representing a range of site water regimes and market orientation. Light intensities incident on the ground were measured along each transect to assess light use. Results showed structural complexity, with full canopy closure in the one or more layers within the canopy for most gardens. The garden architectures made efficient use of light and space, with intersive management for food and fuel production. Farmers grew the crops for both cash and family subsistence. One home garden on a comparatively dry site with shallow soil seemed less structured, with only a single broken canopy layer, but with diverse species of plants.The results indicate that development of gardens in this area utilized existing trees, thinning them to leave the most useful, and inserting other desirable trees and shrubs in the understory and in open spaces. This strategy seemed to maximize light use, regardless of market orientation.This look at the structure and composition of four home gardens, in a forested area of current immigration, demonstrated (1) variety of organization and plant components, (2) different architecture for different soil/site conditions and market orientations, and (3) efficient use of available light through the arrangement of plants. 相似文献
2.
The importance of the role of local community forestry institutions towards forest conservation is exemplified through a comparison of two adjacent areas within the Central Yucatan Peninsular Region (CYPR) in which Land-Use Cover Change (LUCC) analyses were conducted. We also used logistic regression analyses to examine key environmental, socioeconomic and institutional drivers associated with deforestation. One of the areas, La Montaña (LM) at Hopelchen, Campeche, is part of the northern section and buffer zone of the Calakmul Biosphere Reserve (CBR) as well as part of the Mesoamerican Biological Corridor. LM is an agricultural forest frontier region economically dependent on productive activities. The other study, Zona Maya (ZM), found at the municipality of Felipe Carrillo Puerto in Quintana is characterized by having developed community-based forestry enterprises with world wide recognition. In addition, the major tourism industry in nearby Cancun and Riviera Maya provide an important source of off-farm labor and temporary migration. Results show contrasting annual deforestation rates among the two study areas, being greater in the Campeche site (0.7% from 2000 to 2005) compared to Quintana Roo (−0.002% from 2000 to 2004). Logistic regression results show that the occurrence of land clearing at LM is significantly related to demographic variables as well as soil-environment types and conservation status did not reveal to relate to LUCC processes at all. At Quintana Roo, despite twice the population density, population variables at large did not strongly correlate to forest clearing. Rather forest conservation or maintenance was shown to be influenced by local community forestry institutions and a landscape zoning provided by larger management goals from the part of the communities. Greater availability of wage labor for the prominent tourism economy may also reflect a lesser dependence on agriculture and contribute to the much lower deforestation rate. Nonetheless, results show that community forest management can play an effective role in forest conservation. We argue for a regional land use management approach as a conservation strategy in which local inhabitants are considered key actors. 相似文献
3.
Solis-Calderon JJ Segura-Correa VM Segura-Correa JC Alvarado-Islas A 《Preventive veterinary medicine》2003,57(4):199-208
The main objective of this cross-sectional study was to estimate the seroprevalence of infectious bovine rhinotracheitis (IBR) in a population of non-vaccinated beef cattle in the livestock region of Yucatan, Mexico and to determine potential risk factors related to the seroprevalence. Also, we estimated the intraherd correlation (re) and design effect (D) of IBR seropositivity. Cattle were selected by two-stage cluster sampling. Blood samples were collected from 564 animals from 35 herds. Sera were tested for antibodies against IBR using the serum-neutralisation test. Information regarding the herd and each animal sampled were recorded through a personal interview with the farmer or farm manager. The data were analysed using fixed-effects logistic multiple regression. Thirty-four of the 35 herds had at least one seropositive animal. The animal true seroprevalence was 54.4%. Animals in large herds or in production had higher odds of seropositivity than those in small herds or growing. The re and D were 0.17 and 3.62, respectively. 相似文献
4.
José Ramos-Zapata Roger Orellana Patricia Guadarrama Salvador Medina-Peralta 《Journal of plant nutrition》2013,36(5):855-866
Arbuscular mycorrhizal fungi (AMF) can act as an extension of the root system of their host plants. In Desmoncus orthacanthos Martius (Arecaceae), which has thick and unbranched roots (i.e., magnolioid roots) and low densities of root hairs, this association may be essential to reach a maximum growth with minimum fertilizers. This is important because of the potential in the south of Mexico to use D. orthacanthos' shoots as a raw material to build handcrafts. To evaluate the effect of arbuscular mycorrhizae on phosphorus (P) uptake and initial growth of D. orthacanthos seedlings, a 160-day bi-factorial experiment was carried out in which plants were subject to one of two levels of mycorrhizal colonization (with or without) and one of three levels of P substrate addition (4, 12, and 24 ppm). Our results show that total dry weight (DW) and leaf area (LA) responded significantly to P addition but not to mycorrhizal colonization. Phosphorus concentration in plant tissues (Pt) was increased by both factors (mycorrhizae and P addition). Mycorrhizae increased relative growth rate (RGR) at low P level. Our results indicate that AMF play an important role in early growth and P uptake by D. orthacanthos seedlings; therefore, the AMF must be considered in plantations of this potentially economically important palm. 相似文献
5.
Fishing operations and adaptive strategies of small‐scale fishers: insights for fisheries management in data‐poor situations 
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下载免费PDF全文 A. Saldaña S. Salas A. M. Arce‐Ibarra E. Torres‐Irineo 《Fisheries Management and Ecology》2017,24(1):19-32
Small‐scale fisheries' management is complex given its multigear, multispecies nature; despite this, fishing effort has usually been controlled by nominal units, ignoring changes in effective fishing effort. This study aimed to understand the adaptive strategies of small‐scale fishers in San Felipe, Yucatan, Mexico through an analysis of their fishing operations. Minor changes in trip numbers among three seasons were observed, but increases in fishing time, depth and travel costs from one season to another at the operational level were found. It was also evident that high value species at the beginning of the season were gradually replaced by low‐value finfish as the season progresses. The results provide insights for new adaptive management strategies according to fisher's adaptive responses. For instance, using boats or fishing trips as fishing effort units in Yucatan may not be the most appropriated unit for management, as fishers adapt their strategies at different levels. 相似文献
6.
In the Yucatan, cenotes or water sinkholes formed by the dissolution of limestone and surrounded with a characteristic dense layer of heterogeneous vegetation, are the main sources of water for plant and animal assemblages. We investigated their importance to bats by comparing the assemblage structure and diversity between tropical forest and pastureland, with and without cenotes. We set ground level mist nets, sub-canopy nets and harp traps for 96 nights and caught 2819 bats of 26 species and six families. Forest had a greater bat species diversity and abundance than pastureland, as well as rare and threatened species. In forest, sites with and without cenotes had a similar bat assemblage structure and diversity, whereas in pastureland there was a greater species diversity and abundance and number of rare and threatened species at cenotes than sites without cenotes. Chrotopterus auritus and Micronycteris schmidtorum, both threatened in Mexico, and Eptesicus furinalis, were exclusively captured at cenotes. We suggest that it may be the vegetation around cenotes rather than the water bodies per se that attracts many bat species in pastureland. Cenotes are threatened by nitrate contamination from untreated domestic and animal waste and fertilizers and the removal of vegetation to allow livestock access to water. In Yucatan’s agricultural landscapes, protection of cenotes and their characteristic vegetation is key not only for bat conservation but also because they represent potential seed sources for the regeneration of the lowland forest, in which bats play key roles as pollinators and seed dispersers. 相似文献
7.
A. Sotelo E. Contreras S. Flores 《Plant foods for human nutrition (Dordrecht, Netherlands)》1995,47(2):115-123
The chemical and toxicological composition of ten wild legumes collected in Yucatan, Mexico was determined. For each species the whole fruit, (seed and pod), were studied as well as the seed and pod separately. A higher protein content was found in the seeds ofA. lebbeck andP. saman (37.07 and 37.60% respectively). In the seeds ofL. longystilus, C. yucatanensis andP. keyense a high concentration of fat was found, especially in the first with 31.34%. A high quantity of fiber was found in the pods. In general, the samples were rich in lysine (especially seeds) and scant in sulfur amino acids and tryptophan. All the samples showed high concentration of potassium and calcium. Some of them exhibited significant concentrations of iron. The pods ofP. saman and P. keyense showed a high content of lectins. In the seeds ofC. yucatanensis and in the pod ofP. keyense high concentrations of trypsin inhibitors were found 60 and 406.7 TUI/mg sample respectively. The presence of saponins, was detected in seven samples, of which the seed ofP. keyense had the highest concentration. Alkaloids were found only in the whole fruit and pod ofP. saman and cyanogenic glucosides were present inA. pennatula. In general terms, the whole legume showed better digestibility than the pods alone. 相似文献
8.
In Southern Mexico and Central America, inland fisheries form part of the livelihood portfolio of an as-yet unknown number of rural communities. This paper reports on the first comprehensive study of such fisheries located in common property lands (ejidos) of the Mayan Zone in Quintana Roo, Mexico. Given the “data-sparse” nature of these fisheries, with a lack of data available on their current status and on participation levels, a fishery assessment approach was used which included methods from both the natural and social sciences, with a focus on survey methods applied to fishery users, water, fish and creel surveys. Moreover, local knowledge of community residents complemented scientific knowledge in a substantial part of the research. The results, from 48 fishing sites (four with sub-saline waters, the remainder freshwater) indicated (1) a resource base of multi-specific nature with a total of 18 bony fish species in the study area, (2) artisanal (small-scale) fisheries, with very basic technology (notably hand-lines) utilized primarily through barefoot fishing along the shores, or with the aid of rafts and canoes, (3) seasonal fishing, primarily during the dry season (February to May), due to greater accessibility of the sites in those periods, but also related to the end of work on major local livelihoods, (4) both indigenous (Mayan) and non-indigenous fishers, of ages ranging from teenage to senior adults, for most of whom the major occupation was slash-and-burn agriculture, and (5) a mainly male-oriented fishery, but with some women involved in five out of nine ejidos studied. While the key motivation of fishers was subsistence, the study found, for the first time in this form of fishery, that recreation was also a significant goal of many participants. In terms of methodology, the study demonstrated the importance of cross-validating the accuracy of information from informants interviewed in the type of social surveys used here. This combined assessment approach proved effective in providing new information on these previously under-studied fisheries, and may be useful in similar data-sparse situations elsewhere. 相似文献
9.
A.H. Parsons R.E. Wells 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》1989,18(4):90-92
Mean values and ranges for 16 hematological parameters for healthy, young, sexually-mature Yucatan miniature swine are presented. No significant differences were observed between sexes with regard to hemograms. Comparison of observed values with those published in the literature for standard domestic and other breeds of miniature swine reveals no major differences. 相似文献
10.
J. Martínez-Castillo P. Colunga-GarcíaMarín D. Zizumbo-Villarreal 《Genetic Resources and Crop Evolution》2008,55(7):1065-1077
Lima bean (Phaseolus lunatus L.) is an important crop in traditional Mayan agriculture of the Yucatan Peninsula, Mexico, its Mesoamerican center of diversity.
Genetic erosion in this species is currently a threat in this region out of 3 of 21 landraces dominate 71.24% of the cultivated
area, and 12 are rare landraces grown only in 6.29%. Using 90 ISSR loci, we estimated the diversity and genetic relationships
for 21 landraces to analyzing their risk of genetic erosion, and generate data for their in situ conservation. Total genetic diversity was high (h = 0.29), however it was lower than wild gene pool reported (h = 0.69). The abundant landraces had genetic diversity values lower (h = 0.13, I = 0.17) than the common (h = 0.26, I = 0.33) and rare landraces (h = 0.24, I = 0.27). However, the rare landraces are in a higher risk of genetic erosion due to local extinction. The cluster analysis
showed no groups corresponding to morpho-phenological characteristics, geographic origin or traditional classification, which
resulted from high inter-landraces gene flow levels. The molecular data confirmed that the domesticated Lima bean pool of
the Yucatan Peninsula has a high risk of genetic erosion. If current tendencies in landrace cultivation continue, many will
no longer be planted within two to three generations, with a consequent loss of their alleles. Programs urgently need to be
established for in situ conservation of Lima bean landraces in this region. 相似文献