Impacts of Climate Change on the Distribution of Larix Spp. and Pinus Sylvestris and Their Climatypes in Siberia

Inter- and intraspecific effects of climate change were assessed for the dominant conifers of Siberia (60–140^∘E and 48–75^∘N): Larix spp. (L. sibirica, L. dahurica, and L. sukaczewii) and Pinus sylvestris . The approach employed a tri-variate (degree-days above 5 ^∘C, degree-days below 0 ^∘C, and a moisture index) estimate of the climatic envelope within which exists the actual ecological distribution of a species and their constituent climatypes (genotypes physiologically attuned to similar environments). Limits of the actual ecological distribution were approximated by reducing the climatic envelope according to effects of permafrost and interspecific competition. Climatypes were mapped within the climatic envelope according to the climatic interval that must separate populations for reasonable assurance of genetic differentiation. This interval was calculated from response functions that related 13-year growth and survival of a species to the difference in climate between the provenance of a climatype and the climate of numerous test sites distributed across Russia. Mapping species' distributions and their climatypes was done for the contemporary climate and for future climates predicted by the HadCM3GGa1 scenario of Hadley Centre. The results showed that if the forests of the future are to reflect the adaptedness of today, the distribution of species will shift and genotypes within species will be redistributed. Some contemporary climatypes are projected to disappear from Siberia while others common elsewhere would evolve. To mitigate these effects, climatypes should be transferred today to the expected future location of their climatic optima, a distance that is likely to approach 700–1200 km for these species.     

杨树产业对宿迁市生态环境的影响及反思

杨树产业所导致的生态环境的破坏是当前宿迁市环境保护工作中出现的新问题。在对宿迁杨树产业的由来、发展现状进行简要介绍后,着重分析了杨树产业对宿迁生态环境的影响,并对如何使宿迁的杨树产业走可持续发展的道路提出了自己的意见,最后还对如何避免此类问题的出现进行了思考。     

高温气冷堆新燃料运输事故频率分析

商用高温气冷堆核电站是中国未来可能发展的第四代核电站,其新燃料元件和运输容器有显著的特点.探索了将概率安全评价(PSA)方法引入放射性物品运输的辐射风险评价中,首先用故障树方法分析了高温气冷堆新燃料元件公路运输的潜在事故频率,经过事故情景分析、力学分析和临界分析,选择了货包辐射水平升高和临界两种潜在事故予以分析.结果表明,货包辐射水平升高的事故频率很低;临界事故的频率极低,在后续的风险评价中可忽略.     

模拟酸雨对木兰科树种叶片膜脂过氧化和抗氧化系统的影响

酸雨对森林、水体和农田等生态系统造成的危害受到许多研究者的重视,并已取得一些成果,但关于木本园林植物的伤害机理及抗性机制没有得到澄清,尤其是对抗氧化系统的影响研究较少。采用盆栽法,以木兰科(Magnoliaceae)树种抗酸性强的阔瓣含笑(Michelia platypetala)和抗酸性弱的红花木莲(Manglieta insignis)为试材,研究了不同pH值模拟酸雨处理对叶片膜脂过氧化和抗氧化系统的影响。结果表明,随着酸雨pH值的下降,两树种叶片抗氧化剂抗坏血酸(ASA)和谷胱甘肽(GSH)质量分数下降;抗氧化酶超氧化物歧化酶(SOD)及谷胱甘肽还原酶(GR)活性下降,而过氧化物酶(POD)活性变化趋势不一致,阔瓣含笑一直呈上升趋势,红花木莲则先上升后下降。此外,超氧阴离子(O2?·)产生速率上升,丙二醛(MDA)含量和膜透性增加;相关性分析表明,O2?·产生速率与MDA和膜透性呈显著正相关,与抗氧化酶SOD,GR和抗氧化剂ASA质量分数呈显著负相关,说明酸雨降低了植物体防御活性氧伤害有关的酶系统和非酶系统抗性能力,提高了体内活性氧含量,膜脂过氧化加剧。与红花木莲相比,阔瓣含笑具有较强的抗氧化能力。本研究结果从自由基的产生及清除的角度,探讨木本园林植物的伤害机理以及抗性机制,也为该类园林树种在江南城市中的选择提供一些科学参考依据。     

基于C5.0决策树和时序HJ-1A/B CCD数据的神农架林区植被分类

我国神农架林区海拔高、气候复杂,森林类型多样,结构破碎,森林遥感分类难度较大。将2013年时间序列HJ-1A/B CCD遥感影像作为数据源,计算出植被指数(NDVI、DVI、RVI)和主成分第一分量(PC1),使用DEM数据生成地形因子(高程、坡度、坡向),构建植被分类时序因子集。运用C5.0决策树分类法将神农架林区植被细分为七类:针叶林;针阔混交林;落叶阔叶林;常绿和落叶阔叶混交林;常绿阔叶林;灌丛和草甸。结果表明:该方法的总体精度为72.7%,Kappa系数为0.67;在6~8月,针叶林、草甸和灌丛的植被指数明显低于常绿阔叶林、常绿和落叶阔叶混交林、落叶阔叶林和针阔混交林,对分类的贡献较大,称为植被分类的"窗口期"。PC1、NDVI和高程因子对神农架林地的区分度较高,而坡度、坡向和RVI因子对分类帮助不大。作为一种智能分类方法,C5.0决策树分类方法应用于30m分辨率的时间序列HJ-1A/B CCD数据,能够将地貌复杂的神农架林区植被分为七类,提高了类别精度,具有更高的应用价值。     

Characterizing the Spatial Pattern of Soil Carbon and Nitrogen Pools in the Turkey Lakes Watershed: A Comparison of Regression Techniques

There is considerable spatial heterogeneity in organic carbon (C), total nitrogen (N), and potentially mineralizable nitrogen (PMN) pools in the soils of the Turkey Lakes Watershed. We hypothesized that topography regulates the spatial pattern of these pools through a combination of static factors (slope, aspect and elevation), which influence radiation, temperature andmoisture conditions, and dynamic factors (catenary position,profile and planar curvature), which influence the transport ofmaterials downslope. We used multiple linear regression (MLR)and tree regression (TR) models as exploratory techniques todetermine if there was a topographic basis for the spatialpattern of the C, N and PMN pools. The MLR and TR modelspredicted similar integrated totals (i.e., within 5% of eachother) but dissimilar spatial patterns of the pools. For thecombined litter, fibric and hemic layer, the MLR models explaineda significant portion of the variance (R² = 0.38, 0.23 and0.28 for C, N and PMN, respectively), however, the residuals werelarge and biased (the smallest contents were over-predicted andthe largest contents were under-predicted). The TR models (9-branch), in contrast, explained a greater portion of the variance (R² = 0.75, 0.67 and 0.62 for C, N and PMN, respectively) and the residuals were smaller and unbiased. Based on our sampling strategy, the models suggested that static factors were most important in predicting the spatial pattern of the nutrient pools. However, a nested sampling strategy that included scales where both static (among hillslopes) and dynamic (within hillslope) factors result in a systematic variation in soil nutrient pools may have improvedthe predictive ability of the models.     

Importance of conserving large and old trees to continuity of tree-related microhabitats

Protecting structural features, such as tree-related microhabitats (TreMs), is a cost-effective tool crucial for biodiversity conservation applicable to large forested landscapes. Although the development of TreMs is influenced by tree diameter, species, and vitality, the relationships between tree age and TreM profile remain poorly understood. Using a tree-ring-based approach and a large data set of 8038 trees, we modeled the effects of tree age, diameter, and site characteristics on TreM richness and occurrence across some of the most intact primary temperate forests in Europe, including mixed beech and spruce forests. We observed an overall increase in TreM richness on old and large trees in both forest types. The occurrence of specific TreM groups was variably related to tree age and diameter, but some TreM groups (e.g., epiphytes) had a stronger positive relationship with tree species and elevation. Although many TreM groups were positively associated with tree age and diameter, only two TreM groups in spruce stands reacted exclusively to tree age (insect galleries and exposed sapwood) without responding to diameter. Thus, the retention of trees for conservation purposes based on tree diameter appears to be a generally feasible approach with a rather low risk of underrepresentation of TreMs. Because greater tree age and diameter positively affected TreM development, placing a greater emphasis on conserving large trees and allowing them to reach older ages, for example, through the establishment of conservation reserves, would better maintain the continuity of TreM resource and associated biodiversity. However, this approach may be difficult due to the widespread intensification of forest management and global climate change.     

胡杨年轮记录的塔里木河下游54年来区域水环境历史变迁

通过胡杨（Populus euphratica Oliv．）树木年轮宽度的分析,建立了塔里木河下游大西海子（A）、阿克墩（B）、亚合甫马汗（c）、英苏（D）、阿布达勒（E）、喀尔达依（F）、吐格买莱（G）、阿拉干（H）、依干不及麻（I）和考干（J）10个采样区过去54a来的STD、RES和ARS年表,并借助RES年表,采用年代际变化分析和突变检验,反演了塔里木河下游54a年来区域水环境状况变迁时空格局。结果表明：①下游10个样区54a来区域水环境状况具有多样性和复杂性,并不完全表现为距离下游上段（大西海子水库）越近其水环境状况就越好,区域水环境状况总体变异程度由低到高排序为A、G、C、H、E、D、I、B、F、J,也反映了下游10个样区生态退化程度的差异;②下游54a来区域水环境状况最好时期出现在20世纪60年代和21世纪初,大部分区域最差时期主要集中在20世纪90年代,是下游地区长达30a断流水环境变干累积效应的体现;③下游10个样区区域水环境变化具有明显的突变时间,突变出现时间相对水文事件年代具有滞后性。胡杨年轮记录的塔里木河下游54a来区域水环境时空变迁格局对下游生态退化的历史认识具有重要意义。     

树皮在大气有机氯农药监测中应用的研究进展

有机氯农药(Organochlorine pesticides,OCPs)曾在全世界被大量使用,即使禁用多年,仍能在各种环境介质中被广泛检出,对生态环境和人体健康存在着潜在的威胁。因此OCPs的环境迁移和归趋一直是该领域的研究热点。树皮是一种天然的被动采样器,能够很好的反映出大气有机物长期的污染程度。本文简要论述了树皮作为被动采样器在大气污染物监测研究中应用的优势,并对OCPs在树皮中的残留浓度、特征及影响其富集的因素进行了探讨,最后特别针对具有手性的OCPs在树皮中的对映体选择性特征进行了评述。     

Predicting how defaunation-induced changes in seed predation and dispersal will affect tropical tree populations

The loss of large animals due to overhunting and habitat loss potentially affects tropical tree populations and carbon cycling. Trees reliant on large-bodied seed dispersers are thought to be particularly negatively affected by defaunation. But besides seed dispersal, defaunation can also increase or decrease seed predation. It remains unclear how these different defaunation effects on early life stages ultimately affect tree population dynamics. We reviewed the literature on how tropical animal loss affects different plant life stages, and we conducted a meta-analysis of how defaunation affects seed predation. We used this information to parameterize models that altered matrix projection models from a suite of tree species to simulate defaunation-caused changes in seed dispersal and predation. We assessed how applying these defaunation effects affected population growth rates. On average, population-level effects of defaunation were negligible, suggesting that defaunation may not cause the massive reductions in forest carbon storage that have been predicted. In contrast to previous hypotheses, we did not detect an effect of seed size on changes in seed predation rates. The change in seed predation did not differ significantly between exclosure experiments and observational studies, although the results of observational studies were far more variable. Although defaunation surely affects certain tree taxa, species that benefit or are harmed by it and net changes in forest carbon storage cannot currently be predicted based on available data. Further research on how factors such as seed predation vary across tree species and defaunation scenarios is necessary for understanding cascading changes in species composition and diversity.