不同治沙措施对荒漠绿洲过渡带植物群落与土壤因子的影响

沙漠化是河西走廊荒漠绿洲过渡带土地退化的主要原因,科学合理的治沙措施能够有效控制风沙侵害,有助于植被-土壤系统的重建与恢复。多年来,治沙措施的研究主要集中在不同时间梯度下某种给定措施对植物群落及土壤的影响方面,对于同一时间段内不同类型措施产生的生态惠益尚缺乏足够认识。鉴于此,以流动沙地丘间地为对照,选取围栏封育+麦草沙障(Ge+Ws)、麦草沙障+人工梭梭(Ws+H)和尼龙沙障+人工梭梭(Nn+H)3种不同的治沙措施区为研究对象,通过群落学调查与土壤因子测定,研究了不同治沙措施影响下植物群落数量特征和土壤因子的变化规律与相互关系,并对各措施的生态效益进行了评价。结果表明：(1)植被方面,3种治沙措施影响下草本层和灌木层群落数量特征均呈增加趋势,其中Ge+Ws草本层恢复效果较佳,Ws+H和Nn+H灌木层恢复程度更明显;土壤方面,伴随植物群落的恢复,3种治沙措施均能大幅改善土壤全碳、全氮、有机质等主要养分,但同时对土壤水分带来负面效应,Ge+Ws、Ws+H及Nn+H的表层土壤含水量依次减少了37.99%、 31.37%和35.94%。(2)结构方程模型显示,治沙措施通过直接影响灌木和草本群落...     

不同修复措施对黄河源退化高寒草甸植物群落与土壤养分的影响

为了揭示退化高寒草甸逆向转变的驱动因子,通过野外调查和室内分析相结合的方法探究了黄河源不同修复措施(施有机肥F、免耕补播N、施有机肥+免耕补播FN)处理高寒草甸植物群落特征、土壤理化性质和两者相关性的变化规律,阐明不同修复措施对黄河源退化高寒草甸植物群落与土壤养分的影响。结果表明：免耕补播显著增加草甸物种丰富度指数(P<0.05);施有机肥+免耕补播显著增加草甸植物盖度、总生物量、Shannon Wiener多样性指数和Pielous均匀度指数(P<0.05)。不同人工修复后草甸植物功能群地上、地下生物量变化趋势基本一致(除豆科)。和对照相比,莎草科,杂类草地上和地下生物量含量在N、FN处理分别降低83.04%、73.86%、30.43%、92.37%和96.51%、84.09%、85.68%、95.36%;禾本科地上和地下生物量含量在F、N和FN处理分别增加7.29%、23.45%、17.93%和6.04%、4.03%、10.52%;豆科地上生物量含量基本保持不变,地下生物量含量在F、N和FN处理分别降低24.43%、82.19%和42.61%。F显著增加土壤有机碳含量(...     

棘冠海星暴发及其对珊瑚礁的生态影响研究进展

棘冠海星的反复暴发是导致印度—太平洋区域珊瑚礁生态系统退化的最主要原因之一。然而,我国对棘冠海星的研究非常有限。本文综述了国内外关于棘冠海星及其暴发的生态影响和应对策略的研究进展,得出以下主要结论：1)雌性棘冠海星个体每年产卵数量高达50万—2亿个,环境因素变化只要导致幼虫和幼体存活率的轻微提高,成体就将得到大量补充;2)棘冠海星暴发的阈值为1000—1500个/km²,暴发周期为10—27 a,每次暴发持续1—10 a,最终可能以“种群集体感染疾病而崩溃”结束;3)棘冠海星暴发对印度洋及太平洋东部和北部珊瑚礁的破坏性非常小,却直接导致太平洋的西部和南部珊瑚礁90%以上的珊瑚死亡,并通过改变珊瑚群落组成、减少珊瑚和鱼类多样性而对珊瑚礁产生间接影响;4)关于棘冠海星暴发原因的假说中“陆地营养物质输入假说”和“捕食者过度捕捞假说”得到了最普遍的认可,但都不能解释所有的暴发事件;5)应对棘冠海星暴发的主要策略有改善水质、设立保护区、投放天敌和人工清理等,其中人工清理是最直接有效的策略,但迄今并没有发现可长期抑制棘冠海星暴发的方法。因此,急需加强对棘冠海星的深入研究,探查...     

基于地质灾害敏感性的生态安全格局关键区识别与修复——以济南市为例

区域生态安全格局构建对提升生态系统服务功能提供了重要路径,同时统筹各种生态要素进行生态保护与修复分区也是新时期做好生态修复的重要举措。以济南市为例,基于现状生态系统类型分布,聚焦生态本底和地质灾害敏感性的特征,基于形态学空间格局分析方法和自然保护区结合进行生态源地提取。采用夏季降水、植被覆盖度、坡度3个地质灾害敏感性因子修正基本生态阻力面。并采用最小成本路径方法（Least-Cost Path method,LCP）提取生态廊道,构建了市域的生态安全格局。采用电路理论进行生态关键区域（生态"夹点"和生态障碍点）的识别,进一步划分生态修复改善区,并对此提出针对性的生态保护修复策略和工程措施。研究表明：1）市域生态源地的个数为35个,面积为567.15 km²,主要类型为林地和草地。空间上主要分布南部山区。生态廊道818.42 km,平均廊道长度为12.99 km,廊道分布存在较为明显的空间分布差异性,整体呈现出"一屏、一带、三轴"的生态安全格局。2）识别的生态修复关键区包含生态"夹点"25处,历城区生态"夹点"分布最为密集。全市亟需修复的生态障碍点共34处,面积为6.90 km²,主要分布章丘区。生态改善区共识别2994.84 km²,近期亟需修复的面积为96.1 km²,主要分布在长清区、历城区、莱芜区。3）通过对比生态修复关键区和现状土地利用类型,因地适宜的制定了生态修复策略与工程措施布置指引方向。研究结果可为济南市国土空间生态修复规划提供一定的技术支撑,同时也可为其他地质灾害敏感性区域的生态修复规划提供指引。     

A new method for ageing wild boar using dental measures

Over the last decades, wild boar (Sus scrofa) populations in Europe have increased with impacts on agriculture, livestock and biodiversity. Thus, changes in population management for wild boar are increasingly important. Knowledge of the age structure of the population is crucial to designing effective management plans. However, the costs and efforts required to estimate the age of wild boar, primarily in the oldest animals, is problematic for managers and researchers. Here, we describe a new method to estimate wild boar age based on simple dental measures (the external aperture of the pulp cavity, root length and crown length from primary and secondary incisors). Our study was based on data from 93 wild boar of known age belonging to two different populations in central and south-eastern Spain. We propose a model based on Boosted Regression Trees (BRT). Our results show a final age estimation model that included all the explanatory variables proposed (dental measures) and showed a high percentage of estimated deviance (61%), obtained by cross-validation. Thus, at least in Iberian wild boar populations, our method constitutes a low-cost and reliable method for wild boar age estimation.     

Comparison of Treatment Outcome Measures for Irritable Bowel Syndrome

We have examined the relations among three common treatment outcome measures in irritable bowel syndrome (IBS): end of treatment global ratings by a physician, end of treatment patient global ratings, and measures derived from a daily symptom diary completed by the patient. Eighty-four IBS patients (53 female, 31 male) participated in a randomized controlled evaluation of three psychological treatment conditions for IBS. Treatment outcome measures from this trial (Blanchard et al., 1992) were used in the present methodological study. Physician global ratings were significantly correlated with patient global ratings (r = .45, p < .01). Both of these global ratings also correlated significantly with a composite score from patient diary ratings. Multiple regression analyses revealed that reductions in bloating and constipation account for 18% of the variance in patient global ratings. Global ratings at end of treatment by either patient or physician were only partially related to symptom relief as measured by a daily diary.     

Issues in performing arts teacher preparation program evaluation policy

Solid, well-grounded teachers can be instrumental in solving the problems facing our schools and students because it is successful teachers who are the most valuable, in-school contributors to our students' success. The importance of teacher preparation programs (TPPs) in developing quality teachers has been reinforced by researchers who have demonstrated that preparation linked directly to practice benefits teachers in their first year of teaching. In contrast, federal legislation and government officials' statements suggest that TPPs are responsible for many of the problems facing public education, which has resulted in additional regulations and systems designed to evaluate TPPs' success in preparing effective teachers, including graduates' knowledge of appropriate content. In order to analyze the status of TPP evaluation as it relates to arts education, past models for TPP assessment are reviewed, newer models are discussed, and the possible effects on teacher evaluation processes are outlined. Early research and scholarly writing into the noted and projected effect of these models are discussed as well as suggestions and implications for future models and research into TPP effectiveness.