This study suggests that one of the most productive (and most neglected) uses of social science research in forestry development projects is to examine foresters' beliefs regarding rural peoples. This suggestion is illustrated with data from the Forestry Planning and Development Project, Pakistan's first nation-wide social forestry project.The operational component of this project, intended to assist small farmers to cultivate trees on their farmlands, ran into immediate difficulties. Many of the foresters involved insisted that small farmers were simply not interested in tree cultivation. A comprehensive base-line study subsequently was carried out to examine the validity of this belief. The results of this study (confirmed by the subsequent experience with the project in the field) varied markedly from the foresters' beliefs.While many of the foresters believed small farmers were opposed to having trees on their farms and would not agree to plant trees under the project, most farmers already had trees on their farms and expressed interest in planting more; while many foresters believed farmers would only be interested in planting large blocks of market-oriented exotics, most farmers requested small plantings of multi-purpose native trees; while many foresters believed farmers would plant trees only for market sale, most farmers requested trees to meet household needs for fuel and timber; and while many foresters did not think that increasing supplies of fuelwood could reduce the burning of dung, all of the evidence provided by the farmers suggested that it would.The disparity between farmer reality and forester belief is attributed to failures on the part of both foresters and social scientists — failure by foresters to distinguish their non-empirical beliefs about farmers from their empirically-based knowledge of trees, and failure by social scientists to recognize the belief systems of foresters as a legitimate and important object of study. Their study comprises three parts: finding out what the foresters think the farmers want, finding out from the farmers what they actually want, and then analyzing and explaining the differences. 相似文献
Anthropogenic grasslands, meaning grasslands that have been influenced and modified by humans, are one of the most important land covers of the tropics, but their management is dominated by conflicted and contested views, which is reflected in the problematic record of grassland development intervention. This chapter analyzes the historic, cultural, political, and institutional factors that affect the way grasslands are viewed, drawing largely on data from Southeast Asia. These data suggest that perceptions of grasslands are colored in part by the marginal place that they occupy in the cosmology of western industrialized societies, which idealize forest covers. Consequently, national and international agencies view grasslands not as a common land cover but as a development problem. The agendas of government and development agencies are often not grounded in a proper understanding of the local human and bio-physical ecology of grasslands or of successful local agroforestry practices; and research on many of the most important dimensions of grassland management is poorly conducted and/or utilized. The recent rise in scientific interest in indigenous knowledge, environmental history, and non-equilibrium systems, has opened up new possibilities for the study of grasslands. Agroforestry, given its inherent bridging of nature and culture, is ideally suited to benefit from these possibilities, by focusing research attention on the bio-social factors that determine the appearance, disappearance, and maintenance of anthropogenic grasslands.
Swidden agriculture is today the focus of a great deal of debate in the context of agroforestry development in humid, tropical countries. This paper argues that much of this debate deals not with the empirical facts of swidden agriculture, however, but rather with widely-accepted myths, and that this explains the widespread failures of developmental schemes involving swidden agriculturalists. The paper examines three of these myths in some detail. One myth is that swidden agriculturalists own their land communally (or not at all), work it communally, and consume its yields communally. The truth is that their land (including land under secondary forest fallow) is typically owned by individual households, it is worked by individual household labor forces and/or by reciprocal but not communal work groups, and its yields are owned and consumed privately and individually by each household. A second myth is that swidden cultivation of forested land is destructive and wasteful, and in the worst cases results in barren, useless grassland successions. The truth is that swidden cultivation is a productive use of the forests, indeed more productive than commercial logging in terms of the size of the population supported, and forest-grassland successions are typically a function not of rapaciousness but of increasing population/land pressure and agricultural intensification — the grasses, including Imperata cylindrica, having value both as a fallow period soil-rebuilder and as cattle fodder. A third myth is that swidden agriculturalists have a totally subsistence economy, completely cut off from the rest of the world. The truth is that swidden agriculturalists, in addition to planting their subsistence food crops, typically plant market-oriented cash crops as well, and as a result they are actually more integrated into the world economy than many of the practitioners of more intensive forms of agriculture. In the conclusion to the paper, in a brief attempt to explain the genesis of these several myths, it is noted that they have generally facilitated the extension of external administration and exploitation into the territories of the swidden agriculturalists, and hence can perhaps best be explained as a reflection of the political economy of the greater societies in which they dwell. 相似文献
Dry matter intake (DMI), dry matter digestibility (DMD), and fecal output (FO) are difficult to measure directly in the field, and indirect methods using external and internal markers have thus been developed. An experiment was conducted consisting of two digestion trials with two periods in each trial to examine the use of five odd-chain alkanes (C25 to C33) of plant cuticular wax as internal markers to estimate DMD of hay or hay plus concentrate diets in horses. Eight mature Thoroughbred geldings were housed in 4- x 4-m stalls and randomly assigned to one of two mixed grass/legume hays (Diets 1 and 2) in Trial 1 and to mixed grass/legume hay plus one of two concentrates (Diets 3 and 4) in Trial 2. After the first 12-d period was conducted, dietary assignments for each group were switched for the second period in each trial. Each period consisted of a dietary accommodation from d 1 to 7 and total fecal collection from d 8 to 11. Results indicated that fecal recoveries of odd-chain alkanes were 88 to 90% for Diet 1, 75 to 92% for Diet 2, 71 to 81% for Diet 3, and 71 to 82% for Diet 4. Alkane recoveries were not related to alkane chain lengths. Digestibilities calculated from alkane concentration data adjusted using the mean fecal recovery of individual odd-chain alkanes (DA1) were not significantly different from the digestibilities estimated from total collection (DTC) for Diets 1 and 2 in Trial 1 and Diets 3 and 4 in Trial 2. When adjustment was based on the mean recovery of all alkanes (DA2; estimated by linear regression), all DA2 estimates for horses offered all diets were similar to DTC. Results indicate that accurate mean estimates of DMD can be obtained by using plant wax alkane markers and adjusting for the mean recovery of five odd-chain alkanes in a diet. 相似文献
In bacteria, promoter recognition depends on the RNA polymerase sigma subunit, which combines with the catalytically proficient RNA polymerase core to form the holoenzyme. The major class of bacterial promoters is defined by two conserved elements (the -10 and -35 elements, which are 10 and 35 nucleotides upstream of the initiation point, respectively) that are contacted by sigma in the holoenzyme. We show that recognition of promoters of this class depends on the "flexible flap" domain of the RNA polymerase beta subunit. The flap interacts with conserved region 4 of sigma and triggers a conformational change that moves region 4 into the correct position for interaction with the -35 element. Because the flexible flap is evolutionarily conserved, this domain may facilitate promoter recognition by specificity factors in eukaryotes as well. 相似文献
A cooperative research study involving 353 litters was conducted at three stations to determine the effects of graded levels of supplemental Cr from chromium tripicolinate (CrPic) on reproductive performance of sows and preweaning performance of their pigs. Primiparous and multiparous sows were fed fortified corn-soybean meal diets with supplemental levels of 0, 200, 600, or 1,000 ppb Cr (as-fed basis). Each station used at least three of the supplemental Cr levels, with two of those levels being 0 and 200 ppb. Station effects were observed for sow gestation weight gain, lactation weight change, lactation feed intake, litter size at birth and weaning, and pig weight at birth and weaning (P = 0.001 to 0.087). Supplemental Cr increased the number of pigs born live per litter (9.49, 9.82, 10.94, and 10.07; quadratic, P = 0.05) and sow lactation weight change (-0.2, 0.8, -4.1, and -3.9 kg; linear, P = 0.01) but decreased individual birth weight of total pigs born (1.61, 1.57, 1.47, and 1.56 kg; quadratic, P = 0.10). Tissues were obtained from a subset of sows from one station after they had completed three parities on the study. The content of Cr in the adrenal gland (16.4, 20.0, 34.0, and 48.4 ppb), kidney (35.8, 56.4, 132.6, and 176.0 ppb), and liver (22.8, 37.4, 87.6, and 92.2 ppb) was increased linearly (P = 0.001 to 0.005) by increasing CrPic supplementation. The results suggest that the supplementation level that maximizes the biological response is above that currently allowed. Additionally, supplementation of Cr at 1,000 ppb (five times currently permitted supplementation levels) was not detrimental to sow performance, even when fed continuously for three parities. There may be merit to continued research to evaluate higher supplementation rates. 相似文献
The complexity of biomineralized structures suggests the potential of organic constituents for controlling energetic factors during crystal synthesis. Atomic force microscopy was used to investigate the thermodynamic controls on carbonate growth and to measure the dependence of step speed on step length and the dependence of critical step length on supersaturation in precisely controlled solutions. These data were used to test the classic Gibbs-Thomson relationship and provided the step edge free energies and free energy barriers to one-dimension nucleation for calcite. Addition of aspartic acid, a common component in biomineralizing systems, dramatically affected growth morphology and altered the magnitude of the surface energy. 相似文献