陕西省油松混交林木质残体储量与腐烂特征

木质残体是油松针阔混交林的重要组成部分,具有多种的生态功能,对生态系统的稳定和发展有着不可忽视的作用。以陕西省黄龙山林区为研究区域,设置1 hm2(100 m×100 m)的固定样地,研究典型油松针阔混交林木质残体的储量组成、优势树种的空间关系、腐烂特征及密度与含水量,研究结果表明:(1)研究区油松针阔混交林内木质残体的总储量为10.73 t·hm–2,倒木是林分内木质残体的主要来源。在径级组成结构上,径级20 cm以上的木质残体储量占总储量的绝大部分。腐烂等级中,以腐烂等级Ⅱ与腐烂等级Ⅲ的木质残体贮量最多;(2)利用线性模型模拟该林分木质残体的分解密度与含水量,其拟合结果显示木质残体的密度随着腐烂等级的增加而呈现下降趋势,而含水量则随着腐烂等级的增加而呈现升高的趋势;(3)林分内主要研究树种(油松、白桦和山杨)之间在小空间尺度上呈负关联,大尺度下呈正关联,顶级树种与先锋树种间达到互利共生,群落具有较大稳定性。林分内种间竞争的结果将为地带性顶级树种油松代替白桦与山杨等先锋树种。天然油松针阔混交林木质残体的贮量组成及腐烂特征反映了该区森林群落演替后期阶段木质残体的结构特征,本文的研究结果为我国黄土高原针阔混交林生态系统的管理和保护以及可持续经营提供科学依据。     

Spatial distribution of coarse woody debris in pine forests of the Marii El Transvolga region

The spatial distribution of coarse woody debris in pine forests has been studied in the Transvolga region of the Marii El Republic. For this purpose, 30 test plots have been established in pine (Pinus sylvestris) stands of the study region. The results are indicative of a tendency toward the spatial grouping (clustering) of woody debris by fractions, decomposition classes, and stocks along with increase in stand age.     

Structure and Dynamics of Coarse Woody Debris Stocks in Middle-Taiga Bilberry Pine Forests

Russian Journal of Ecology - The purpose of this study was to ascertain the stocks of coarse woody debris (CWD) in bilberry pine forests in the southern part of the Republic of Karelia (the middle...     

Carbon fluxes from coarse woody debris in southern taiga forests of the Valdai Upland

Studies in three typical forest biotopes of the Valdai Upland were performed to evaluate the stocks and surface area of coarse woody debris from spruce and birch (in linear transects), its colonization by xylotrophic fungi (during reconnaissance surveys), and CO₂ emission (by a chamber method). The stock and surface area were minimum in a paludal birch forest (46.4 m³/ha and 960 m²/ha) and maximum in a decay area of spruce forest (256.1 m³/ha and 3761 m²/ha, respectively). The assemblages of wood-decay fungi had a composition typically found in southern taiga forests. The total CO₂ flux varied from 145 kg C-CO₂/ha per year in the paludal birch forest to 462 kg C-CO₂/ha per year in small herb–green moss spruce forest. It is concluded that air temperature is an informative predictor of seasonal C-CO₂ flux rate from coarse woody debris.     

Exploring correlation between redox potential and other edaphic factors in field and laboratory conditions in relation to methane efflux.

Methane is primarily a biogenic gas, which is implicated in global warming. Although its production in the anoxic conditions is regulated by several edaphic factors, aquatic macrophytes also influence methane emission by providing aerenchyma to act as chimney for CH4 transport from the sediment to troposphere, by releasing root exudates to the sediment to serve as substrate for methanogenic bacteria and by transporting atmospheric O2 to rhizosphere, which stimulates CH4 consumption. Among the edaphic factors, redox potential (Eh) is the most important, which largely determines the action of methanogenic bacteria. Hence, a study was undertaken first to find out the correlation between CH4 emission and edaphic factors in the field conditions and then to understand the relationship between Eh and other edaphic factors. The field studies revealed that natural wetlands were the major source of CH4 emission, and the vegetation plays an important role in CH4 emission from the water bodies. However, it was very difficult to establish a strong relationship between the CH4 emission and the edaphic factors in the field conditions due to other limiting factors and their constant fluctuations. In this connection, the laboratory experiments exhibited that soil temperature, pH, moisture regime and incubation period were negatively correlated with Eh, which determines the initiation of methanogenic process. However, organic carbon and the water regime over the soil surface did not show any impact on Eh in this study.     

Carbon Emission from the Surface of Coarse Woody Debris in Korean Pine Forests of Southern Primorye

Carbon dioxide fluxes from the surface of coarse woody debris (CWD) have been measured in Korean pine forests of the southern Sikhote-Alin mountain range. The seasonal dynamics of oxidative conversion of CWD carbon have been evaluated, and average values of the CO₂ emission rate have been determined for CWD fragments of three tree species at different stages of decomposition. The degree of decomposition is an important factor of spatial variation in CO₂ emission rate, and temporal variation in this parameter is adequately described by an exponential function of both CWD temperature and air temperature (R² = 0.65–0.75).     

Latitudinal Gradients of Trophics in Ural Macrolepidoptera: The Role of Food Quality

The Macrolepidoptera fauna of the Urals, from the southern to the northern boundary of the forest zone (i.e., from the forest–steppe of the Southern Urals to the forest–tundra of the Polar Urals) has been analyzed. It has been demonstrated that the proportion of Lepidoptera feeding on woody plants, including evergreens, increases in this direction. Among the Heterocera, the proportion of species feeding on graminoids decreases; in the Polar Urals, none of these species is specialized. The food spectrum is particularly variable in noctuids and almost invariable in geometrids and Rhopalocera. It is assumed that foods with a low nutrient value (grasses, mosses, lichens, plant debris, wood, and roots of various plants) prevent Macrolepidoptera species from spreading in the Subarctic region. In the Polar Urals, multiyear developmental cycles and wintering at the larval stage are related to feeding on these types of food.     

Aggregated Estimation of the Basic Parameters of Biological Production and the Carbon Budget of Russian Terrestrial Ecosystems: 1. Stocks of Plant Organic Mass

The data presented were obtained at the first stage (1993–1999) of studies on evaluating the basic parameters of biological production in Russian terrestrial ecosystems in order to provide information for assessing and modeling the carbon budget of the entire terrestrial biota of the country. Stocks of phytomass (by fractions), coarse woody debris, and dead roots (underground necromass) were calculated by two independent methods, which yielded close results. The total amount of phytomass in Russian terrestrial ecosystems was estimated at 81800 Tg (=10¹² g = million t) dry matter, or 39989 Tg carbon. Forest ecosystems comprise a greater part (82.1%) of live plant organic matter (here and below, comparisons are made with respect to the carbon content); natural grasslands and brushwoods account for 8.8%; the phytomass of wetlands (bogs and swamps), for 6.6%; and the phytomass of farmlands, for only 2.5%. Aboveground wood contains approximately two-thirds of the plant carbon (63.8%), and green parts contain 9.9%. For all classes of ecosystems, the proportion of underground phytomass averages 26.7% of the total amount, varying from 22.0% in forests to 57.1% in grasslands and brushwoods. The average phytomass density on lands covered with vegetation (1629.9 million hectares in Russia) is 5.02 kg/m² dry matter, or 2.45 kg C/m². The total amount of carbon in coarse woody debris is 4955 Tg C, and 9180 Tg C are in the underground necromass. In total, the vegetation of Russian terrestrial ecosystems (without litter) contains 54124 Tg carbon.     

基于流域演化的泥石流敏感性分析

基于泥石流来源于某些处于特殊演化阶段的分支小流域的理论,分析了面积高程曲线及其参数与泥石流活动的关系。面积高程曲线积分值S表征流域内松散固体物质量,S/2对应的相对高差比值K表征流域源地面积在不同高程的分布,以S和K为参数提出泥石流敏感性分析思路。针对汶川县主要公路(都汶公路和省道303)沿线泥石流敏感性分析,在Arcgis、Matlab等软件的支持下,基于震前1:50 000地形数据,计算了研究区泥石流流域的S和K。根据计算结果,初步判定了各流域的地貌发育阶段,以及流域源地汇水区的高程位置。并根据震后泥石流实际活动情况,对于S小于0.5但又属于震后频发型,或者S值大于0.5但其面积较大且分支较多泥石流沟,进行了次一级子流域的面积高程值计算,判定其易发生泥石流具体源地。最后,根据流域面积高程值S得出了研究区泥石流敏感性分级图,分析结果基本反应了地貌演化对泥石流发生能力的潜在影响。     

Assessing the physiological state of woody plants by parameters of chlorophyll fluorescence in the bark of annual shoots

The relative yield of variable chlorophyll fluorescence in the bark of annual shoots of woody plants was measured with a portable pulse-modulated fluorometer designed for this purpose at the Department of Biophysics (Biological Faculty, Moscow State University). Experiments were performed to study the response of this parameter to external influences (treatment with an herbicide, water loss, etc.). The results demonstrated the possibility of reliably recording the parameters of fluorescence in the annual shoots of various woody plants without damaging these shoots. It is concluded that measurements of chlorophyll fluorescence in the bark of woody plants can be used for analyzing changes in the physiological state of tree stands under the effects of natural and anthropogenic factors.     

汶川地震后四川省安县黄洞子沟泥石流特征

2008年5月12日汶川地震诱发了黄洞子沟流域规模巨大的大光包滑坡,部分滑体前冲堆积于沟道内,直接为后期泥石流的形成提供了丰富的松散固体物质,改变了黄洞子沟泥石流形成条件,使黄洞子沟从一条非泥石流沟演变成了一条高频泥石流沟。震后黄洞子沟几乎每年雨季都会暴发不同规模的泥石流,其中以2013年"7·09"泥石流灾害规模和危害最大。本文着重分析了黄洞子沟泥石流形成特征,并从地形、降水和地质三个方面将黄洞子沟和文家沟进行对比,得出了物源堆积体颗粒粒径与泥石流形成的关系。     

长江（万州段）水体溶解性有机物的荧光光谱分析

按照河床形态、水文条件、排污口分布、支流状况等特点从长江万州段及长江支流苎溪河选取8个断面进行采样，对水样中溶解性有机物（DOM）的荧光光谱特征进行了分析和研究。利用日立F 4500荧光分光光度计对长江水、普通自来水和纯水在紫外光激励下产生的荧光光谱及其特性进行了比较研究。同时，研究了不同水样、不同取样点的水体DOM的荧光特性和三维荧光光谱图。结果表明：长江水在波长290 nm左右的紫外光激励下能产生较强的荧光。荧光峰是350~550 nm 范围的宽谱峰，荧光峰值波长在450 nm左右。但是不同取样点水样的荧光峰强度明显有差异，在4号、5号、2号取样点的水样荧光强度明显高于其他取样点，这与采样点附近污染源排放有明显的关系。该研究方法可作为鉴别水质污染的一种有效的手段.     

大渡河上游沙耳沟泥石流震后特征及其发展趋势

沙耳沟是一条老泥石流沟，处于“5.12”地震的严重波及区。为了研究地震对严重波及区泥石流沟的影响，通过详细的野外调查和勘查，对沙耳沟泥石流震后基本特征和发展趋势进行了探讨。沙耳沟泥石流的性质可判定为“中频率 中~大规模 较高粘度泥石质泥石流”，具有暴雨激发、成灾速度快、危害严重等特点，其危害作用主要为冲毁和淤埋。泥石流物源主要以沟床质起动、沟源侵蚀和沟岸崩滑补给为主，沟内固体物源方量约1300×104 m3，其中可能参与泥石流活动的固体物源动储量约300×104 m3，已经具备暴发中 大规模泥石流的可能性。根据计算，在50 a一遇的暴雨作用下，一次泥石流总量超过9×104 m3；在100 a一遇及更低频率的暴雨作用下，一次泥石流总量超过13×104 m3。通过研究发现，“5.12”地震对地震严重波及区的泥石流沟有一定的影响，但影响不十分明显，其发展趋势仍按自身规律进行演化。     

基于层次分析法的未确知测度理论泥石流危险性评价

将未确知测度理论与层次分析方法相结合用于评价泥石流危险性。根据泥石流危险性的影响因素和等级划分标准，选取泥石流规模、泥石流发生频率、流域面积、主沟长度、最大相对高差、流域切割密度、主沟床弯曲系数、泥砂补给长度比、24小时最大降雨量、人口密度等10个指标作为泥石流危险评价因子，利用未确知测度理论建立泥石流危险性评价指标的未确知测度函数，通过层次分析方法确定各评价指标的权重，依据置信度识别准则对泥石流危险性进行评价，并结合实例进行了对比分析。研究结果表明，基于层次分析方法的未确知测度理论的评价方法评价过程合理、置信度高、结果可靠，为泥石流危险性评价提供了一种新的方法     

Late 20th century mangrove encroachment in the coastal Australian monsoon tropics parallels the regional increase in woody biomass

In Kakadu National Park, a World Heritage property in the Australian monsoon tropics 250 km to the east of Darwin, a number of recent studies have shown that woody encroachment (expansion of woody communities) and densification (increased biomass in woody communities) has occurred in the last 40 years. The cause of this increase in woody biomass is poorly understood, but possibly associated with the control of invasive Asian water buffalo, trend to higher rainfall, and increased frequency of fires. Mangroves provide an important context to understand these landscape changes, given that they are unaffected by fire or feral water buffalo. We examine change in mangrove distribution in a series of coastal tropical swamps fringing Darwin, Northern Territory, Australia over a 30-year period using a series of 7 aerial photographs spanning 23 years from 1974 and a 2004 high-resolution satellite image. In late 1974, Darwin was impacted by an intense tropical cyclone. Vegetation at 3,000 randomly placed points was manually classified, and a multinomial logistic model was used to asses the impact of landscape position (coastal, intertidal, and upper-tidal) and swamp on mangrove change between 1974 and 2004. Over the study period, there was instability and slight mangrove loss at the coast, stability in the intertidal zone, and mangrove gain in the upper-tidal zone, with an overall increase in mangrove presence of 16.2% above the pre-cyclone distribution. A swamp that was impacted by drainage works for mosquito control and the construction of a sewage treatment plant showed a greater mangrove increase than the two unmodified swamps. The mangrove expansion is consistent with woody encroachment observed in nearby but ecologically distinct systems. Plausible causes for this change include changed local hydrology, changes in sea level, and elevated atmospheric CO₂ concentrations.     

Free radicals and chromosome aberrations in leaves of woody plants as a test system for the genotoxicity of the urban environment

A new method for estimating the genotoxicity of the urban environment is proposed. The method is based on the analysis of the lipid peroxidation (LPO) rate in leaves of woody plants. The mutagenicity of the urban environment was estimated using standard test systems, including plant root meristem (kidney beans germinated in water with suspended particles collected at different points along the Temernik River) and the Ames test (silt samples were tested). Sensitivities of elm, willow, and poplar leaf meristem cells to unidentified environmental mutagenes were compared. Frequencies of chromosome aberrations (CAs) in leaves of woody plants growing at different points along the Temernik River within the Rostov-on-Don city districts differed from those in the control zone. The frequency of CAs was found to correlate with the concentration of LPO products. This allows a biochemical estimation of the malonic dialdehyde (MDA) concentration in woody plants to be used as an express test for the mutagenicity of environmental factors. An advantage of the proposed test is the possibility of monitoring the level of unidentified environmental mutagens over many years, independently of its sporadic temporal variations.     

泥石流对岩性的敏感性分析及其在危险性评价中的应用

泥石流对不同岩性的敏感程度存在很大的差异，而岩性在泥石流相关的科学研究中也难以量化使用。本研究选择三江并流区为研究区，采用工程地质岩组划分方法，将研究区的地质岩性分为14个工程地质岩组；进而引入岩性敏感度计算公式Fn = Nn / Sn，分析研究区泥石流灾害点分布与地质岩组的相关性，计算出泥石流对各地质岩组的敏感值。在ArcGIS 90平台的支持下，根据泥石流对岩性的敏感值，将研究区的地质岩性进行量化分级，划分为4个敏感性等级，并将本研究成果应用到三江并流区泥石流危险性评价的应用中。本文选择坡度、岩性、断裂、植被和人类工程活动等5个影响因子为泥石流危险性的评价指标，建立泥石流危险性评价模型，在GIS技术支持下，绘制研究区的泥石流危险性区划图。本研究结果与研究区已有的地质灾害点分布情况基本吻合，充分证明本研究方法是切实可行的，进而可为我国西南地区的地质灾害评价以及防灾减灾工作提供方法指导与参考     

基于小流域单元的怒江州泥石流易发性评价

开展泥石流灾害易发性评价,了解区域泥石流易发程度的整体特征和空间异质性,为区域宏观层面国土空间布局及地质灾害防治规划等提供依据。基于小流域评价单元,选择距断裂带距离、岩性、melton比率、流域延伸率、流域高差率、河流弯曲系数、流域水系密度、平均植被覆盖度、年均降水量、距道路距离、距居民点距离等11个评价指标,采用确定性系数模型CF和多因子叠加权重确定法开展怒江州泥石流易发性评价研究。将易发性评价结果划分为5个等级,并以研究区历史泥石流灾害对易发性评价结果验证。结果表明:极高易发区面积仅占研究区总面积的8.31%,但发生泥石流灾害的数量占泥石流总数的29.75%;高易发区的面积占总面积的12.29%,发生泥石流的数量占22.59%。最后通过独立样本验证,易发性评价模型性能(AUC=0.742)良好。怒江州泥石流灾害易发性评价结果与历史泥石流灾害点空间分布较为吻合,表明选取的易发性评价指标和评价方法可行,评价结果可为怒江州防灾减灾工作提供参考。     

安宁河上游冷渍沟泥石流特征及其发展趋势

冷渍沟是安宁河上游左岸的一级支沟，沟内发育了一大型滑坡 碎屑流，为后续泥石流活动提供充足的松散物质来源。为了研究冷渍沟泥石流的危害特征，在野外调查和实地勘测的基础上，分析了泥石流的形成背景条件及其特征，探讨了泥石流的发展趋势，提出了相应的泥石流防治对策。研究表明，冷渍沟泥石流属于过渡性（亚粘性）高频大规模泥石流，泥石流成灾速度快，危害严重；百年一遇的泥石流容重为21 t/m3，五十年一遇的泥石流容重为20 t/m3，二十年一遇害泥石流容重为19 t/m3，相应的峰值流量分别为12768、8171和3818 m3/s。在常态下，冷渍沟泥石流的发生频率和规模会逐渐减小；但如果近期遭遇强震或者暴雨，一旦滑坡失稳堵塞沟道，将会暴发大规模泥石流，很容易堵断安宁河，对上下游造成严重危害。因此，建议在该流域布设必要的泥石流防治工程；同时加强对沟道两岸和滑坡稳定性监测，做好泥石流发生的监测预警工作     

泥石流与人类经济活动

山地是泥石流与人类共存的环境,泥石流作用于山地环境,强烈地影响人类经济活动：人类经济活动也作用于山地环境,强烈地影响泥石流。泥石流对山地环境的危害,主要为破坏地表、破坏生态系统和淤堵江河;泥石流对人类及其经济活动的危害,主要为破坏城镇,村庄,工矿,交通水利水电工程,农田和人类自身的安全。泥石流危害的结果,能导致山地坡面破碎化、沟口沙石化、河床宽浅化和植被逆向演替化,以及耕地贫瘠化、经济发展滞后化和