Climatic conditions and hence climate change influence agriculture. Most studies that addressed the vulnerability of agriculture to climate change have focused on potential impacts without considering adaptation. When adaptation strategies are considered, socio-economic conditions and farm management are often ignored, but these strongly influence current farm performance and are likely to also influence adaptation to future changes. This study analysed the adaptation of farmers and regions in the European Union to prevailing climatic conditions, climate change and climate variability in the last decades (1990–2003) in the context of other conditions and changes. We compared (1) responses in crop yields with responses in farmers’ income, (2) responses to spatial climate variability with responses to temporal climate variability, (3) farm level responses with regional level responses and (4) potential climate impacts (based on crop models) with actual climate impacts (based on farm accountancy data). Results indicated that impacts on crop yields cannot directly be translated to impacts on farmers’ income, as farmers adapt by changing crop rotations and inputs. Secondly, the impacts of climatic conditions on spatial variability in crop yields and farmers’ income, with generally lower yields in warmer climates, is different from the impacts of temporal variability in climate, for which more heterogeneous patterns are observed across regions in Europe. Thirdly, actual impacts of climate change and variability are largely dependent on farm characteristics (e.g. intensity, size, land use), which influence management and adaptation. To accurately understand impacts and adaptation, assessments should consider responses at different levels of organization. As different farm types adapt differently, a larger diversity in farm types reduces impacts of climate variability at regional level, but certain farm types may still be vulnerable. Lastly, we observed that management and adaptation can largely reduce the potential impacts of climate change and climate variability on crop yields and farmers’ income. We conclude that for reliable projections of the impacts of climate change on agriculture, adaptation should not be seen anymore as a last step in a vulnerability assessment, but as integrated part of the models used to simulate crop yields, farmers’ income and other indicators related to agricultural performance. 相似文献
Artificial insemination (AI) is poorly developed in camelids owing to the difficulty in collecting high quality semen and the highly viscous nature of the semen. Semen collected by artificial vagina (AV) is often of low quality and must be improved before any further development of AI technology can occur. The present study investigated the effects of adding a cervix‐like stricture to the AV, presence of females, collecting semen into Androhep®, skim‐milk or Tris diluents, and catalase supplementation (0, 100, 200 or 600 units/ml) of Tris diluent on alpaca semen quality parameters. The addition of a cervix‐like stricture increased mating length (p < 0.05), whilst the presence of females during semen collection did not improve semen quality parameters (p > 0.05). Collection of semen into Tris diluent improved sperm motility (58.0 ± 11.9%) compared with the control (34.0 ± 10.8%; p < 0.05), Androhep® (33.5 ± 10.7%) and skim‐milk diluents (28.2 ± 10.4%). Semen viscosity was reduced by collection into Androhep® (4.6 ± 1.7 mm) and skim‐milk diluents (3.6 ± 1.3 mm) compared with Tris diluent (5.7 ± 2.1 mm) and no collection medium (9.3 ± 3.5 mm; p < 0.05). Tris diluent supplemented with 100, 200 or 600 units/ml catalase increased semen viscosity (5.0 ± 3.2 and 4.9 ± 3.2 mm). Collection of alpaca semen by AV into Tris diluent increased semen quality facilitating further development of AI technology in alpacas. 相似文献
The present article is attempting to evaluate the to date performance of the BHV-1 eradication campaign currently run in Saxony-Anhalt. Special emphasis is put on the modelling of missing data and an optimum performance--for comparison with the observed progress of eradication. The eradication campaign turned out to have performed almost optimally so far, but problems might arise in its final phase due to insular management deficiencies and violation of laws, as well. Possible sanctions are mentioned. 相似文献
Pure cultures of Treponema hyodysenteriae given orally to conventional pigs resulted in the development of swine dysentery, whereas identical cultures given to gnotobiotic pigs did not produce the disease. Oral inoculation of gnotobiotic pigs with Vibrio coli and/or a peptostreptococcus in addition to T. hyodysenteriae did not result in dysentery. Neutralization of gastric secretions with NaHCO3 immediately prior to inoculation with T. hyodysenteriae increased the period during which treponemes were evident in the feces, as did the inoculation of this organism via the intracecal route. None of the gnotobiotic pigs with a persistent fecal Treponema population developed signs of dysentery. Factors other than those investigated in this work must play a part in the etiology of swine dysentery. 相似文献
A series of experiments was performed to examine the effects of blastomere biopsies on subsequent development of IVF-derived bovine embryos. The first experiment was designed to assess the optimal time for blastomere removal. One blastomere was removed either 48 or 72 h after IVF. Biopsy at 48 h resulted in 17.2% of embryos proceeding to the blastocyst stage, which was lower than when biopsies were performed at 72 h (37.5%, p < 0.05). In the second experiment, embryos were cultured either under atmospheric or 5% O(2) following blastomere removal. Biopsies had no effect on rate of blastocyst formation with 36% of controls and 33.7% of biopsied embryos proceeding to that stage. However, culture under 5% O(2) significantly increased the number of blastocysts from 29.9% to 40.3% (p < 0.05). This effect was significant in both biopsied and control embryos. In the final experiment, biopsied embryos were again cultured under different oxygen tension. Blastocysts were collected and cultured individually for 48 h in medium droplets in their respective O(2) concentration after which time the medium was assayed for concentration of interferon-tau (IFN-tau). Reduced O(2) concentration again significantly increased blastocyst formation from 24.9% to 41.9% (p < 0.05). IFN-tau secretion was not affected by biopsies, but culture under atmospheric O(2) resulted in significantly increased IFN-tau concentration in medium droplets (12274.0 +/- 2825.9 pM vs 5046.5 +/- 2562.2 pM; p < 0.05). 相似文献
A major objective of the ESPACE—wheat programme was to perform by means of open-top chambers (OTCs) ‘standardised’ experimental investigations of spring wheat responses to increased atmospheric CO2 and O3 concentrations and to other environmental stresses at different locations in Europe, representing a broad range of different climatic conditions. From 1994 to 1996 a total number of 25 OTC experiments were carried out. In addition, four growth chamber experiments focusing on key physiological processes of wheat growth in CO2-enriched air were performed. According to the specific needs for subsequent modelling purposes, environmental data were collected during experiments, i.e. air temperature, global radiation, humidity and trace gas concentrations. In the present paper results of these measurements are summarised. It was shown, that the OTC-experiments covered a considerable range of growing season mean-air-temperatures (13.0–23.4°C) and global irradiances (10.8–18.1 MJ m−2 d−1), the most important driving variables for crop growth simulation models. Mean concentrations of CO2 and O3 in ambient air and in different treatments illustrated the observed variability of trace gas exposures between different experiments. Implications for subsequent analyses of biological response data are discussed. 相似文献
The response of crop growth and yield to CO2 and ozone is known to depend on climatic conditions and is difficult to quantify due to the complexity of the processes involved. Two modified mechanistic crop simulation models (AFRCWHEAT2-O3 and LINTULCC), which differ in the levels of mechanistic detail, were used to simulate the effects of CO2 (ambient, ambient ×2) and ozone (ambient, ambient ×1.5) on growth and developmental processes of spring wheat in response to climatic conditions. Simulations were analysed using data from the ESPACE-wheat project in which spring wheat cv. Minaret was grown in open-top chambers at nine sites throughout Europe and for up to 3 years at each site.
Both models closely predicted phenological development and the average measured biomass at maturity. However, intermediate growth variables such as biomass and leaf area index (LAI) at anthesis, seasonal accumulated photosynthetically active radiation intercepted by the crop (ΣIPAR), the average seasonal light use efficiency (LUE) and the light saturated rate of flag leaf photosynthesis (Asat) were predicted differently and less accurately by the two models. The effect of CO2 on the final biomass was underestimated by AFRCWHEAT2-O3 due to its poor simulation of the effect of CO2 on tillering, and LAI.LINTULCC overestimated the response of biomass production to changes in CO2 level due to an overprediction of the effect of CO2 on LUE. The measured effect of ozone exposure on final biomass was predicted closely by the two models. The models also simulated the observed interactive effect of CO2 and ozone on biomass production. However, the effects of ozone on LAI, ΣIPAR and Asat were simulated differently by the models and less accurately with LINTULCC for the ozone effects on LAI and ΣIPAR. Predictions of the variation between sites and years of growth and development parameters and of their responses to CO2 and ozone were poor for both AFRCWHEAT2-O3 and LINTULCC. It was concluded that other factors than those considered in the models such as chamber design and soil properties may have affected the growth and development of cv. Minaret. An analysis of the relationships between growth parameters calculated from the simulations supported this conclusion. In order to apply models for global change impact assessment studies, the difficulties in simulating biomass production in response to CO2 need to be considered. We suggest that the simulation of leaf area dynamics deserves particular attention in this regard. 相似文献