电磁微波共轭杀青对乌龙茶杀青叶理化变化的影响

将电磁微波共轭杀青工艺应用于乌龙茶杀青,通过单因素试验和正交试验,探讨电磁杀青滚筒温度、转速以及微波磁控管开启个数、微波杀青带速等因素对乌龙茶杀青叶理化变化的影响。结果表明,电磁微波共轭杀青较佳工艺参数为：高温滚筒杀青温度310℃,滚筒转速为10 r·min-1,低温滚筒温度150℃,配套微波杀青,微波电磁管开启6个,输送带带速为0.14 m·s-1,且共轭杀青最佳含水率为35％左右。     

21世纪以来我国经济林资源动态变化浅析

基于21世纪以来3次全国森林资源连续清查结果,对我国经济林面积总量、林种结构、品种结构、经济林经营集约化程度等4个方面的动态变化,以及主要树种主产区分布、经济林地稳定性,进行了初步分析,得出了我国经济林资源“总量变化趋于平稳、结构变化较为频繁、主产区分布基本定型、经营集约化程度进一步提升”的初步结论。     

Using ecological trajectories to track long-term taxonomic and functional changes in benthic shallow soft-bottom communities (Bay of Saint-Brieuc,English Channel)

1. Taxonomic and functional trajectories of benthic assemblages were studied in shallow soft-bottom sediments in the bay of Saint-Brieuc (Western English Channel). Changes were assessed at different spatial and temporal scales using a macrobenthic dataset based on 38 stations sampled in 1987 and 2019, coupled with data from one station sampled annually between 2005 and 2019 as part of the European Water Framework Directive monitoring programme.
2. Taxonomic trajectories indicated 1) changes in the structure and distribution of benthic assemblages, 2) an homogenization of the assemblages, and 3) significant functional shifts.
3. Fishing activities and nutrient enrichment are probably strong drivers of the observed changes, as suggested by the higher mortality rate of fragile, flexible, tubiculous and burrowing species, and the increase in the abundance of opportunistic species in the assemblages. Certain populations of macroinvertebrates seem jointly controlled by climate change and by the aforementioned local factors of disturbance.
4. The Community Trajectory Analysis framework appears as a new and interesting method to track ecological changes in marine ecosystems by measuring change with respect to a baseline state, to help define ecological recovery (station returning to the initial ecological state) and departure (station presenting increased changes over time), and to analyse trajectory similarity.
5. According to the degradation of habitat over time, we identify the need for the implementation of knowledge-based conservation strategies, especially within Natura 2000 sites.

     

Challenging conservation of migratory species: Sahelian rainfalls drive first-year survival of the vulnerable Lesser Kestrel Falco naumanni

In the context of attested global changes, accurate estimation of whether climatic fluctuations impact on population demographic parameters is needed for adequate management, especially for migratory species. We present a capture-recapture analysis linking survival rates of the vulnerable Lesser Kestrel (Falco naumanni) to annual rainfalls in the Sahel region, considered as a proxy of climatic conditions on wintering grounds. Recapture data were obtained from field observations of individuals ringed and sexed as juveniles over a 14-year monitoring period (1994-2007). We addressed a common but problematic situation in birds where: (i) sex is known with certainty for first-summer or older birds but only suspected for juveniles, and (ii) a large proportion of individuals never return to the study population (e.g. transient behavior). Transient behavior and unknown sexes were explicitly integrated considering a two age class in a multistate capture-recapture model. Survival was time-varying for juveniles (geometric mean: 0.499 ± 0.021) but constant - and higher - for adults (0.718 ± 0.013). Yearling survival probabilities were strongly correlated with rainfalls in the Sahel, suggesting a high dependence of juvenile upon the wintering conditions. While taking sex uncertainty into account, we detected no sex-dependence in survival. Incorporating the sensitivity of survival of wintering migratory birds to climatic variables such as precipitations in arid Sahelian ecosystem may allow to model conservation scenarios with a greater realism. Finally, we encourage the development of international management strategies for migratory species on wintering areas in addition to the existing conservation actions on summering Mediterranean grounds.     

An integrated watershed modelling framework to explore the covariation between sediment connectivity and soil erosion

Quantitative identification of the covariation between sediment connectivity and soil erosion can contribute to provide the key information for watershed sediment management. However, this covariation and its spatiotemporal response mechanisms are still unclear, especially whether this covariation can be used as a basis for identifying critical source areas of sediment in large-scale ecological restored watersheds. In this study, an integrated methodology framework by the revised universal soil loss equation (RUSLE), index of connectivity (IC) and sediment delivery ratio (SDR) was proposed to visually assess the spatiotemporal characteristics of erosion and sediment yield processes in the Yanhe Watershed with large-scale ecological restoration from 1985 to 2020 and to identify the covariation between sediment connectivity and erosion in subbasins. The soil erosion estimated by RUSLE has decreased by over 80% since 1985 owing to increased vegetation cover and the effective implementation of soil conservation measures, but the upper reaches still have high erosion intensity due to differences in specific controlling factors such as topographic conditions and land cover, requiring focused soil conservation practice. The IC results showed that as the vegetation restoration and soil conservation measures in the Yanhe Watershed varied from year to year, their spatial and temporal patterns had a strong influence on the distribution of sediment connectivity, and some local areas in the middle reaches showed local minima of IC in 1995, 1998 and 2010 mainly due to the implementation of long-term ecological restoration project. The developed IC-Erosion maps indicated that areas with high connectivity but low erosion accounted for over 60% of the total watershed area from 1985 to 1999, demonstrating a reverse correlation between sediment connectivity and erosion. Meanwhile, over 40% of the erosion occurred in a few areas (approximately 20%) with high connectivity and high erosion from 2000 to 2004, which can be characterized as the critical areas of erosion. The methods and results of this study provide ideas for separately defining both erosion and connectivity and quantifying bi-variable erosion–connectivity classification, which can be easily viewed on a scatterplot.     

宁夏盐池沙地不同密度人工柠条林土壤水分时空变化分析

对宁夏盐池退化沙地不同密度的人工柠条林地的土壤水分时空特征进行分析。结果表明:1)林下土壤体积含水量随着深度的增加呈先增大后降低的趋势,在垂直剖面上可分为土壤水分速变层(0-20cm)、活跃层(20-80cm)、相对稳定层(80-100cm);2)土壤水分季节动态变化可划分为:积累期(4-5月);消耗期(6-9月);稳定期(10月至次年4月)3个时期;3)土壤体积含水量随人工林密度增加呈下降趋势,2490丛/hm2和1665丛/hm2可作为该区人工柠条林调控密度的参考依据。     

牛瘤胃酸中毒的血液学及生化指标变化

瘤胃酸中毒是由于牛过量采食含可溶性糖类物质的精饲料,瘤胃内急剧产生、积聚并吸收大量乳酸等物质所致的一种急性消化性酸中毒,危及牛的健康。本文分析了24例病牛的临床表现、血液学和生化指标变化情况。结果表明,病牛主要临床表现为轻症者食欲减退,瘤胃收缩力降低;中度病牛精神迟钝,食欲废绝,呼吸急促;重症病牛陷入昏迷状态,呼吸浅表而快,最后衰竭而死亡。血液学检测结果为病牛的RBC、Hb、Pcv均显著高于健康牛(P<0.05),且随着瘤胃酸中毒的加剧而升高;WBC总数上升,嗜中性白细胞增加而淋巴细胞减少。生化指标检测结果为随病情加重,其血浆二氧化碳结合力及钾、氯、钙等离子不同程度下降;尿素氮含量高于健康牛;轻度酸中毒阶段血糖含量不断增加,但病情严重时则下降。通过本研究,以期为反当动物瘤胃酸中毒的防治提供参考依据。     

Effects of Carbohydrate-free Diets on the Performance of Lactating Mink (Mustela vison) and the Growth Performance of Suckling Kits

The effects of carbohydrate-free diets on body weight changes, feed consumption, and plasma concentrations of nutrients, metabolites, and hormones in lactating mink and on growth performance in kits were investigated in a total of 108 litters during the lactation period of seven weeks. The litters were distributed in three experimental groups fed different ratios of metabolisable energy (ME) derived from protein and fat (61:38; 47:52; 33:66). The females and kits were weighed at parturition and 2, 3, 4, and 7 weeks after parturition. Blood samples were collected from females in the second, fourth, and sixth week of the lactation period. Carbohydrate-free diets fed to lactating mink can in principle support normal performance, health of the females, and growth performance of the kits. However, mink need a sufficient supply of available gluconeogenic precursors in the form of amino acids. In the present experiment, the diet with 33% of ME from protein contained insufficient amounts of gluconeogenic precursors for lactating mink, and three weeks post partum this group was excluded from the experiment. The differences in dietary protein level (61% and 47% of ME) and fat level (38% and 52% of ME) influenced the plasma concentrations of free fatty acids (FFA) and urea, but had minimal influence on plasma concentrations of other nutrients, metabolites, and hormones.     

化德县七号乡生态环境遥感监测及其动态变化研究

以遥感技术对化德县七号乡生态环境进行监测,利用GIS技术对遥感监测结果进行解译与分析,对2005年土地利用现状进行分析,同时对1995～2004年该乡生态环境时空动态变化进行分析与评价。结果表明,七号乡土地利用以草地和林地为主,其次为耕地,居民、交通建设用地面积很小;生态环境动态变化主要特点是林地、草地、水域面积在增加,耕地、农村居民点面积在减少,交通建设用地增加,而未能利用的土地面积在减少。     

鸡传染性贫血病临床症状与诊断

鸡群感染传染性贫血病后通常表现翼部发炎或变蓝,鸡体苍白,软弱无力,全身出血,死亡率增加等症状,剖检典型病变为骨髓退色、贫血、淋巴器官萎缩等。该病可通过鸡与鸡直接接触传播,最可能的感染途径是呼吸道。该文主要从鸡传染性贫血病的病原、流行病学特点、临床症状、病理学变化、诊断等方面对鸡传染性贫血病进行论述。