Evolution of the Minangkabau's shifting cultivation in the West Sumatra highland OF Indonesia and its strategic implications for dynamic farming systems

This paper explores the evolution of the shifting cultivation of the Minangkabau , the biggest matrilineal society in Indonesia, and examines factors underlying the instability and vulnerability of farmers' livelihoods and the degradation of their resource base using an extended factor analysis technique, in order to understand how development strategies might be modified towards a more dynamic farming system. The study distinguished three main phases of the farming system's changes and found that these changes highly corresponded with the emerging market and institutional incentives. Furthermore, the factor analysis generated a six‐factor model suggesting strategic interventions to foster the improvement of farmers' livelihoods and environment in future. In addition, consistent with the results of these factors analysis, we argue that, provided land tenure is conducive, there are substantial possibilities for policies and interventions that focus first on agricultural diversification and then on organization building, to assist in dealing with farmers' vulnerability and environmental degradation in the uplands. Copyright © 2004 John Wiley & Sons, Ltd.     

Stem dimensional fluctuation in Jeffrey pine from variation in water storage as influenced by thinning and prescribed fire

Forest thinning utilizing cut-to-length and whole-tree harvesting systems with subsequent underburning were assessed for their impacts on water storage in the extensible tissues of dominant and codominant trees in an uneven-aged Jeffrey pine (Pinus jeffreyi Grev. & Balf.) stand on the east slope of the Sierra Nevada. Prior to the onset of the third growing season following thinning and the second season after burning, manual band dendrometers were installed at breast height on the selected trees and readings of diurnal fluctuation in stem circumference, an indication of bole water status, were taken monthly for one year. Diameter and relative diameter fluctuation were calculated from the circumference measurements. Overall, thinning had a positive influence on stem water recharge capacity, with the most pronounced effects evident in the latter part of the growing season. During this period, bole contraction in thinned stand portions was 49 to 55% greater than in the unthinned control, suggesting that both a greater volume of stored water was available for transpiration and was transpired in trees of the former treatment. There was no clear evidence that harvesting method affected stem water storage and influences of underburning were also absent entirely. Seasonal effects on diurnal changes in stem diameter were prominent, as the extent to which boles contracted generally increased over the course of the growing season, whereas fluctuations were at a minimum during the colder months. The magnitude of stem dimensional flux was found to be negatively correlated with initial tree DBH in one instance, while negative relationships between the former and live crown length as well as percentage were also revealed, albeit infrequently. Changes in bole size were positively correlated with residual basal area in some cases. These results suggest that improvement in water relations can be realized from density management in a dry site forest type with no apparent compromise of this benefit by broadcast underburning.     

EFFECT OF DAY-NIGHT TEMPERATURE REGIMES ON GROWTH AND MORPHOLOGICAL DEVELOPMENT OF TIMOTHY PLANTS DERIVED FROM WINTER AND SUMMER TILLERS

Winter (vernalized) and summer (non-vernalized) timothy tillers were grown to anthesis in day/night temperature regimes of 32/26°, 27/21°, 21/15°, and 15/10°C. Herbage and total plant yields, total leaf-blade number and area, and total plant growth-rate were highest, or very nearly so, in the 21/15°C regime for both the winter and summer plants. However, summer plants reached anthesis 13 to 14 days later than winter plants in each temperature regime. Even though virtually all primary shoots produced an infiorescence, summer plants had significantiy more leaves and leaf-blade area, produced significantiy higher yields of leaf blade, stem plus sheath, stubble, and root tissues and had a significantly higher total plant growth rate than winter plants in each temperature regime.     

魁北克省多日龄猪接种FLEX系列茵格发(R)猪圆环病毒疫苗预防猪圆环病毒相关疾病(PCVAD)的初步结果

人们认为猪圆环病毒2型(PCV2)是发生断奶仔猪多系统衰竭综合征的一个必要因素.目前断奶仔猪多系统衰竭综合征在欧洲称作猪圆环病毒病(PCVD),在北美称作猪圆环病毒相关疾病(PCVAD).     

Indices of landscape pattern

Landscape ecology deals with the patterning of ecosystems in space. Methods are needed to quantify aspects of spatial pattern that can be correlated with ecological processes. The present paper develops three indices of pattern derived from information theory and fractal geometry. Using digitized maps, the indices are calculated for 94 quadrangles covering most of the eastern United States. The indices are shown to be reasonably independent of each other and to capture major features of landscape pattern. One of the indices, the fractal dimension, is shown to be correlated with the degree of human manipulation of the landscape.     

Evaluation of 3 Assays for Failure of Passive Transfer in Calves

This study examined the sensitivity, specificity, predictive values, and classification accuracy of 3 commonly used screening tests for failure of passive transfer: the sodium sulfite turbidity test, the zinc sulfate turbidity test, and re-fractometry relative to serum immunoglobulin G₁, (IgG₁) concentrations determined by radial immunodiffusion. Serum samples were obtained from 242 calves ranging from 1 to 8 days of age. Using a serum concentration of 1,000 mg/dL IgG₁ to define adequate passive transfer, the zinc sulfate test had a sensitivity of 1.00 and a specificity of 0.52 in the detection of inadequate passive transfer. The endpoint of the test appeared to be higher than desired; calves testing negative had mean serum IgG₁ concentration of 955 mg/dL and a large proportion of calves with adequate passive transfer were misclassified as positive for failure of passive transfer. Using the qualitative zinc sulfate test, the percentage of calves correctly classified with regard to passive transfer status was less than that observed with either the sodium sulfite test or refractometry. The sensitivity of the sodium sulfite assay was 0.85 at a 1+ endpoint and 1.00 at a 2 or 3+ endpoint. The specificity of the sodium sulfite assay varied from 0.87 at a 1+ endpoint and 0.56 at a 2+ endpoint. The sensitivity and specificity of refractometry varied from 0.01 to 1.00 depending on the choice of endpoint. Refractometry correctly classified the largest proportion of calves with regard to their passive transfer status at test endpoints of 5.0 and 5.5 g/dL, 83% and 82% respectively. The highest percentages of calves correctly classified occurred with the sodium sulfite test using a 1+ endpoint (86.30%) and refractometry using a 5.0 g/dL endpoint (83.00%). A regression equation was developed that permitted calculation of an optimal endpoint for refractometric determinations of total serum protein concentration. A serum protein concentration of 5.2 g/dL was equivalent to 1,000 mg/dL serum IgG₁. Optimal selection of tests for passive transfer status in calves will be governed by the prevalence of failure of passive transfer, test performance, and the anticipated costs of classification errors.     

RETROSPECTIVE ASSESSMENT OF COMPUTED TOMOGRAPHIC IMAGING OF FELINE SINONASAL DISEASE IN 62 CATS

Sixty-two cats with sinonasal disease were evaluated with computed tomography. Findings that may lead to a computed tomographic diagnosis of nasal neoplasia versus rhinitis included osteolysis of the paranasal bones, moderate to severe turbinate destruction, lysis of the nasal septum, the presence of a homogenous space occupying mass, and extension of the disease process into the orbit or facial soft tissues. These findings were not pathognomonic for neoplasia and may be associated with severe rhinitis; therefore, nasal biopsy was recommended. When compared with parallel radiographic studies, computed tomography was not more sensitive than radiographs at detecting the presence of nasal cavity abnormalities in cats with referable clinical signs but was more sensitive at localizing these changes and determining the extent of disease.     

Quantifying scale-dependent effects of animal movement with simple percolation models

A simple model of animal movement on random and patterned landscapes was used to explore the problems of extrapolating information across a range of spatial scales. Simulation results indicate that simple relation- ships between pattern and process will produce a variety of scale-dependent effects. These theoretical studies can be used to design experiments for determining the nature of scale-dependent processes and to estimate parameters for extrapolating information across scales.     

Toxicological pathology of cockleburs (Xanthium spp.) for broiler chickens.

Spiking mortality syndrome (SMS) in chickens resembles cocklebur toxicity in cattle, sheep, pigs, and rats. In order to determine if cockleburs are toxic to broiler chicks, crushed burs were fed (25% wt:wt) to broilers for 21 days. Ingestion of cockleburs resulted in significant failure to properly gain body weight. Otherwise, chicks did not develop clinical signs of illness or gross or microscopic lesions. Although there were some significant differences in serum chemistry values among chick groups, there were no consistent patterns. Severe hypoglycemia is said to be a characteristic finding in chicks that die with SMS. Because glucose levels were not low in chicks that were fed cockleburs, we feel certain that cockleburs do not cause SMS.     

Imidazolinone inhibition of acetohydroxyacid synthase in vitro and in vivo

Imidazolinone herbicides inhibit the first enzyme of branched-chain amino acid biosynthesis, acetohydroxyacid synthase. The inhibition of the enzyme in vitro by these herbicides increases with incubation time, but is not irreversible, as deduced by reaction progress curves. In contrast to this result is the apparent irreversible inhibition of the enzyme by these imidazolinones that occurs when the herbicide is applied to intact corn plants. Plants treated with imidazolinone herbicide and then extracted showed dramatically reduced enzyme activity. This effect on extractable enzyme level occurred with several different imidazolinone herbicides in either foliar or soil application. The decrease in extractable enzyme activity could be observed within four hours after treatment. Herbicides other than imidazolinones did not reduce the extractable enzyme level. These findings suggest that the enzyme- imidazolinone interaction in vivo may be different from the interaction observed in vitro.