1986—2015年青藏高原哈拉湖湖泊动态对气候变化的响应

湖泊是气候变化的敏感指示器,研究其动态变化对揭示全球气候变化具有重要意义。以哈拉湖流域为研究区,基于3S技术提取流域内湖泊面积、形状等信息,揭示近30年哈拉湖流域湖泊动态变化特征,并探讨其对气候变化的响应。结果表明：1986—2015年间,哈拉湖流域湖泊面积变化呈“V”型,其动态变化大致可分为两个阶段：波动下降阶段（1986—2001年）和波动上升阶段（2001—2015年）。其中1986—2001年湖泊面积由593.68 km²减少到584.83 km²（减少8.85 km²）;2001—2015年由584.83 km²增加到614.31 km²（增加29.48 km²）。对湖泊面积变化量与冰川面积变化量及同期遥感数据阶段各气候要素相关分析发现,湖泊面积变化量与阶段降水量呈正相关,且相关显著性水平在0.01以上,进而降水量是湖泊动态变化的主导因素。     

基于土地利用的中国城镇化SD模型与模拟

中国正处在快速推进的城镇化进程中,耕地与林地、牧草地和水域等生态用地将如何变化,以及建设用地是否仍将快速增长?这不仅是国家宏观政策制定者关心的问题,也是广大学者和普通民众面临的具体问题。通过构建基于土地利用的中国城镇化系统动力学（System dynamics,SD）模型,尝试对上述问题作出分析。研究结果表明：（1）本文构建的模型是有效的,具备可靠性和稳定性。（2）若要保持国家耕地保有量不少于18.25亿亩,到2050年需补充83.17万~412.67万hm²耕地资源。（3）到2050年,如果中国城镇化水平达到78%左右,建设用地总量将达到4007.29万~4214.25万hm²,较2020年净增加了155.87万~342.88万hm²。（4）2020—2050年生态用地数量表现为先增加后减少,其中,林地显著增加,牧草地减少,水域略有增加。研究成果可为全国国土空间规划多方案模拟、评估和决策提供科学服务。     

分子模拟方法在爆炸反应机理方面的应用进展

针对爆炸过程反应机理异常复杂,实验检测手段对其认识匮乏的现状,综述了量子化学、反应分子动力学等分子模拟方法的特点及研究进展,分析了分子模拟技术在燃爆机理研究中的应用进展,包括量子化学方法对于燃料热解/燃烧、瓦斯等可燃体系爆炸过程的微观基元反应步骤、反应能垒及热力学参数的计算,以及反应分子动力学(ReaxFF MD)在含能材料、可燃混合气等复杂爆炸体系获取可能的反应路径及中间自由基变化的应用。对分子模拟方法在爆炸领域研究的应用提出了建议及展望,指出ReaxFF MD和密度泛函理论(DFT)相结合是一种研究复杂爆炸体系微观反应机理极具潜力的方法,借助先进的分析检测手段对模拟方法的验证及修正,能获取更准确、全面的微观反应动力学模型。     

Evaluating the success of functional restoration after reintroduction of a lost avian pollinator

Conservation translocation is a common method for species recovery, for which one increasingly frequent objective is restoring lost ecological functions to promote ecosystem recovery. However, few conservation translocation programs explicitly state or monitor function as an objective, limiting the ability to test assumptions, learn from past efforts, and improve management. We evaluated whether translocations of hihi (Notiomystis cincta), a threatened New Zealand passerine, achieved their implicit objective of restoring lost pollination function. Through a pollinator-exclusion experiment, we quantified, with log response ratios (lnR), the effects of birds on fruit set and seed quality in hangehange (Geniostoma ligustrifolium), a native flowering shrub. We isolated the contributions of hihi by making comparisons across sites with and without hihi. Birds improved fruit set more at sites without hihi (lnR = 1.27) than sites with hihi (lnR = 0.50), suggesting other avian pollinators compensated for and even exceeded hihi contributions to fruit set. Although birds improved seed germination only at hihi sites (lnR = 0.22–0.41), plants at sites without hihi had germination rates similar to hihi sites because they produced 26% more filled seeds, regardless of pollination condition. Therefore, although our results showed hihi improved seed quality, they also highlighted the complexity of ecological functions. When an important species is lost, ecosystems may be able to achieve similar function through different means. Our results underscore the importance of stating and monitoring the ecological benefits of conservation translocations when functional restoration is a motivation to ensure these programs are achieving their objectives.     

努力创建地震预报的应用基础学科——兼论板内现今地壳运动动力学

分析地震预报已取得的成就和面临的困境,根据国内外各相关学科的新进展,作者认为创建地震预报的应用基础学科是当务之急。一种可能的选择是,在现今地球动力学、动力大地测量学(地壳形变学)、实时大地构造学及系统科学、非线性动力学等前沿学科的交叉部位上,逐步建立板内现今地壳运动动力学(或板内现今构造微动态动力学、或板内地壳形变系统动力学)。它既是地震、火山、滑坡、泥石流等灾害预测的应用基础,又是立脚于中国的全球变化研究。对它的意义、研究对象、内容与方法作了探讨,最后提出了一批建议着手开展的应用基础研究课题。     

秦岭中段撂荒地植被恢复过程中土壤微生物代谢特征

明确撂荒地植被恢复过程中土壤微生物养分限制特征及其驱动机制对揭示土壤养分循环和维持生态系统稳定具有重要意义.以秦岭中段不同年限撂荒地为研究对象,通过测定土壤理化性质、5种胞外酶活性[β-1,4-葡萄糖苷酶(BG)、纤维二糖水解酶(CBH)、β-1,4-N-乙酰基氨基葡萄糖苷酶(NAG)、亮氨酸氨基肽酶(LAP)和酸性磷...     

塔里木河下游输水前后NDVI差异分析

运用统计方法分析塔里木河下游英苏、喀尔达依、阿拉干三断面输水前后归一化植被指数(NDVI)的差异大小并推测河畔植被对输水的响应程度。结果表明:随着输水进行,研究区NDVI与地下水埋深逐渐呈负相关趋势,NDVI增幅随地下水埋深减小逐渐增大;输水前后相同断面NDVI差异极显著,根据输水前后NDVI差值大小确定植被恢复速度为:英苏>喀尔达依>阿拉干;各断面NDVI在输水前没有差异,输水后断面间NDVI差异显著,根据差异大小确定恢复程度顺序为英苏>喀尔达依>阿拉干;以大西海子水库周边NDVI为参照,确定经7年8次生态输水英苏、喀尔达依、阿拉干三断面植被恢复度分别为20.2%、18.4%和8.4%。以上研究表明,研究区植被恢复仍然有限,坚持持续输水很有必要。     

植物群落对铜尾矿废弃地土壤微生物量和酶活性的影响

以铜尾矿废弃地为对象,研究了铜尾矿废弃地上植物群落发展与表层尾矿微生物量C、N和脱氢酶、过氧化氢碱性磷酸酶和脲酶活性的变化,探讨了植物群落-微生物量C、N_土壤酶活性之间的相互关系.结果表明,随着植物群落的发展,铜尾矿废弃地表层尾矿微生物量和酶活性在不断增加;铜官山老尾矿废弃地白茅群落下表层尾矿(TBM)微生物量和酶活性与杨山冲尾矿废弃地及铜官山新尾矿废弃地表层尾矿微生物量和酶活性存在显著差异性(p<0.05).相关分析表明铜尾矿废弃地表层尾矿微生物量C、N与土壤有机质、总氮之间呈显著正相关(P<0.01);脱氧酶、碱性磷酸酶及脲酶与微生物量C、微生物量N、土壤有机质、总氮之问呈显著正相关(P<0.01),但过氧化氢酶与微生物量C、微生物量N、土壤有机质、总氮之间呈显著负相关(P<0.01).     

Assessing the impact of biological control of Plutella xylostella through the application of Lotka–Volterra model

The Lotka–Volterra model was applied to the population densities of diamondback moth (DBM), Plutella xylostella (L.) and its exotic larval parasitoid Diadegma semiclausum (Hellen) data that was collected earlier by icipe's DBM biological control team. The collections were done for 15 months before the release and 36 months after release of the parasitoid in two areas; in Werugha, Coast Province of Kenya and Tharuni, Central Province of Kenya, respectively. For each area in pre- and post-release periods, we estimated Lotka–Volterra model parameters from the minimization of the loss function between the theoretical and experimental time-series datasets following the Nelder-Mead multidimensional method. The model estimated a reduction in the value of the steady state of DBM population from 4.86 to 2.17 in Werugha and from 6.11 to 3.76 and 3.45 (with and without exclusion of the time before D. semiclausum recovery) in Tharuni when transiting from the pre- and post-release periods, respectively. This change was a consequence of the newly introduced parasitoid, in the areas. The study presented a successful and detailed technique for non-linear model parameters restoration which was demonstrated by the correct mimicking of empirical datasets from the classical biological control with D. semiclausum, in different areas of Kenya. The applied model has measured the parasitoids impact on the DBM biological control through a quantitative estimate of the effectiveness of the newly introduced species D. semiclausum. These equations may therefore be used as tool for decision making in the implementation for such pests’ management system strategy.     

Recruitment and attrition of associated plants under a shading crop canopy: Model selection and calibration

Associated plant and animal diversity provides ecosystem services within crop production systems. The importance of the maintenance or restoration of diversity is therefore increasingly acknowledged. Here we study the population dynamics of associated annual plants (‘weeds’) during the growth of a crop in a season and introduce a minimal model to characterize the recruitment and attrition of the associated plants under the influence of shading by the crop. A mechanistically based, logistic, light interception model was parameterized with light interception measurements in two single crops (barley and rye) and in mixtures of these cereals with peas. Population dynamics data were collected for the annuals Papaver rhoeas, Centaurea cyanus, Chrysanthemum segetum, and Misopates orontium. A minimal population dynamics model was identified for each annual plant species, using system identification techniques as model selection and calibration.