基于RS和GIS的青海湖流域植被覆盖度变化与驱动因子研究

基于2001—2010年MOD13Q1数据,采用像元二分模型估算近年青海湖流域的植被覆盖度,分析其时空变化规律,探讨植被覆盖度与气象因子、地形因子之间的关系。结果表明:在青海湖流域,年平均植被覆盖度呈中部高、西北低的态势,中高覆盖度面积最大,占流域总面积的60%以上;近10年流域平均植被覆盖度呈波动上升趋势,最大值出现在2010年;NDVI在年际尺度上与气温的相关性并不显著,但与降雨量呈显著正相关关系(R=0.79),降雨量与植被覆盖度年际变化总体趋势较为相似;植被覆盖度随高程和坡度的增大均先增大后减小,最大值出现在海拔3500—4000m、坡度2°—6°的缓平地上;阳坡的植被覆盖度大于阴坡,而平地最小。     

“十二五”期间高平市空气质量特征及其与气象要素的关系

基于高平市2011~2014年间的常规污染物浓度监测数据并结合同期气象资料,分析了高平市的空气质量变化特征,并讨论了空气污染指数与气象要素之间的相关关系。结果表明,高平市的空气质量从2013年开始下滑,空气良好率下降了7个百分点;首要污染物以PM_(10)为主;空气污染指数月变化具有统计学意义,季变化差异无统计学意义;气象因素与空气污染密切相关,气压、相对湿度与空气污染指数呈显著正相关,全年降水量、风速、气温与空气污染指数呈显著负相关;气温与空气污染指数间的相关性最高,其次为风速;东南气流为主导风向时往往给高平市带来优良空气质量,而北西北风向常伴随着污染日的出现。     

四种短命植物若干生态学特性的研究

1.前言短命植物是温带荒漠地带重要的植物类群之一,通常被定义为:生长发育周期短暂,在春末夏初约两个月左右的时间内迅速完成全部生长周期的一年生草本植物,主要分布于北非、西亚、中亚、北美、南美和澳大利亚等广大地区的干旱荒漠中,亦存在于部分草原、山地草甸和山地林中,以苏联中亚地区较为繁茂,在我国,短命植物主要分布于新疆西北部荒漠及毗邻的草原植被中,局部地段可构成优势层片,甚或形成群聚,从而使北疆植被显著区别于我国其     

玛纳斯河流域上游气候及径流变化特征分析

本文以我国西北干旱区玛纳斯河流域为例,研究玛纳斯河流域上游近50年径流与气候的变化趋势。根据玛纳斯河流域上游肯斯瓦特水文站(1959-2010年)和煤窑水文站(1980-2007年)系列径流量及气象资料,采用线性趋势、五年滑动平均以及Mann-Kendall检验方法,分析玛纳斯河流域上游气候及径流量多年变化特征。结果表明:1近50年玛纳斯河流域上游气温、降水量均呈现上升趋势,其中煤窑水文站增加趋势比较明显;2由于受气温和降水量增加趋势的影响,近50年玛纳斯河径流量也呈现出明显增加趋势;3径流量从1997年开始发生突变,在2002年达到显著性水平,即进入丰水期,表明近50年玛纳斯河流域气候呈现由冷干向暖湿转变。     

发展芦苇湿地污水处理绿色生态工程初论

1问题的提出新疆地处中温带（温带与暖温带）欧亚大陆腹部极端干旱的荒漠地带。四周高山环绕，远离海洋，自然地理环境封闭，是形成新疆干旱自然生态环境的地理基础。其典型的温带大陆性气候决定了新疆气候干燥、少雨、多大风、日较差和年较差大的特征，且冬季寒冷漫长、夏季炎热短促，全年平均降水量为145mm，降水量稀少，只有全国平均降水量630rum的23％，而蒸发量约为2000mrn－2500mm，干燥度在4一伤之间。根据干旱指数分区指标，全区除北疆、天山山区、阿勒泰山区和塔城北部山区干旱指数在5以下属于干旱、半干旱地区外，其余地区干旱指…     

新疆石河子垦区生态系统特征分析(摘要)

从新疆温带干旱、半干旱气候与地貌特征出发,对石河子的城乡生态系统作了调查与资料统计,对该地区的水资源、植被、土地状况和经济等作了现状与动态分析,提出了干旱、半干旱地区城乡发展的主导因子是水资源的保护和开发利用。水质、水量是城乡人民生存的基础,也是建立城乡、发展城乡生态系统的重要依据。水资源的保护与合理开发利用决定着石河子城乡气候因子的动态变化、绿色复盖率和城乡经济的发展;植被的保护起着调节该地区气候与水份     

株洲市臭氧污染状况及相关气象因子分析

采用2013年1～12月空气质量自动监测数据对株洲市臭氧污染现状及相关气象因子进行分析。结果表明:监测期间全年臭氧日最大8 h平均浓度一级标准值达标率达到71.8%,全年超标率为1.6%,超标主要出现在季节变换时期。臭氧日最大8 h平均浓度的月均值变化呈"M"型,浓度高值持续时间长。日变化规律较强,且不同季节变化特征略有差别。臭氧浓度与气温有正相关性,相关系数为0.612;与湿度和云量有负相关性,且臭氧与湿度负相关性较明显,相关系数为0.731。     

红水河流域1961—2011年极端气温变化特征分析

以红水河流域1961—2011年9个气象站点的月平均气温、月平均最高气温、月平均最低气温为基础,运用气候倾向率、小波分析、Mann-Kendall突变检测法和反距离插值法对流域50年的极端气温变化进行时空定量分析。结果表明:1流域平均温度、极端高温和极端低温的气候倾向率呈上升趋势,平均气温和极端低温的气候倾向率均低于全国水平,而极端高温的气候倾向率高于全国水平。2流域极端高温的突变年为2002年和2009年,极端低温的突变年为1985年,平均温度突变年为1996年。3流域50年来极端高温存在着28年左右的震荡周期,极端低温在14—17年较大的时间尺度上经历了低—高—低—高的变化过程,中小尺度上6—8年的周期变化明显,而流域的平均温度存在27年左右的震荡周期。4流域极端高温变幅较大,总体上呈西北高、东南低的空间分布格局,极端低温呈"冷—热—冷—热"的空间分布格局,平均气温总体上呈典型的经向分布特征。     

成都地区2014～2020年PM10变化特征及气象条件分析

利用相关分析、逐步回归等统计方法,考察了成都地区PM₁₀的变化趋势及不同气象要素对PM₁₀变化的作用。结果表明,成都地区PM₁₀逐年递减,月际尺度上呈典型的“U”型分布。PM₁₀质量浓度的变化与最大风速、降水量及气压、日照时数、平均风速的变化负相关,与气温及相对湿度的变化正相关。不同季节影响PM₁₀变化的典型气象因子不同,冬、春季最大风速影响最大,夏、秋季平均风速影响最大。通过建立PM₁₀变化的多元回归预测模型,为成都地区PM₁₀变化的预测及管控措施的制定提供了科学依据。     

内蒙古赤峰地区草麻黄资源的分布及利用

本文论述了内蒙古赤峰地区草麻黄的分布和生态特性。草麻黄从东南至西北受气温和降水等因素的影响,在东南部丘陵沙地干草原区集中分布;在中部低山丘陵干草原区呈零星分布,在西北部山地草甸草原区无分布。草麻黄对干旱的环境条件适应能力强,具有耐干旱、耐沙湿、耐高温、耐寒、耐贫瘠和不耐水湿等生态特性。本文对如何保护与合理利用草麻黄资源,提出了建议。     

Soil Carbon Sequestration Potential for “Grain for Green” Project in Loess Plateau,China

Conversion of cropland into perennial vegetation land can increase soil organic carbon (SOC) accumulation, which might be an important mitigation measure to sequester carbon dioxide from the atmosphere. The “Grain for Green” project, one of the most ambitious ecological programmes launched in modern China, aims at transforming the low-yield slope cropland into grassland and woodland. The Loess Plateau in China is the most important target of this project due to its serious soil erosion. The objectives of this study are to answer three questions: (1) what is the rate of the SOC accumulation for this “Grain for Green” project in Loess Plateau? (2) Is there a difference in SOC sequestration among different restoration types, including grassland, shrub and forest? (3) Is the effect of restoration types on SOC accumulation different among northern, middle and southern regions of the Loess Plateau? Based on analysis of the data collected from the literature conducted in the Loess Plateau, we found that SOC increased at a rate of 0.712 TgC/year in the top 20 cm soil layer for 60 years under this project across the entire Loess Plateau. This was a relatively reliable estimation based on current data, although there were some uncertainties. Compared to grassland, forest had a significantly greater effect on SOC accumulation in middle and southern Loess Plateau but had a weaker effect in the northern Loess Plateau. There were no differences found in SOC sequestration between shrub and grassland across the entire Loess Plateau. Grassland had a stronger effect on SOC sequestration in the northern Loess Plateau than in the middle and southern regions. In contrast, forest could increase more SOC in the middle and southern Loess Plateau than in the northern Loess Plateau, whereas shrub had a similar effect on SOC sequestration across the Loess Plateau. Our results suggest that the “Grain for Green” project can significantly increase the SOC storage in Loess Plateau, and it is recommended to expand grassland and shrub areas in the northern Loess Plateau and forest in the middle and southern Loess Plateau to enhance the SOC sequestration in this area.     

近50年新疆沙尘暴频率时空变化趋势分析

采用新疆54个气象站近50年的气象资料,分析新疆沙尘暴时空分布特征、年际和年内演变趋势及年际演变的影响因素。结果显示：新疆沙尘暴近50年以来空间分布特征是南疆多于北疆,沙尘暴主要出现在3～10月,其中4～7月为高发时段。年际演变趋势20世纪80年代以来较60、70年代都有所减少;80年代以后沙尘暴发生日数减少。     

Germinable Soil Seed Banks and the Restoration Potential of Abandoned Cropland on the Chinese Hilly-Gullied Loess Plateau

Poor vegetation cover is generally considered to be a major factor causing soil erosion on the Loess Plateau in China. It has been argued that tree planting restoration is ineffective, and natural re-vegetation is an alternative ecological solution for restoring abandoned cropland and controlling soil erosion. The aims of this study were to investigate the characteristics of soil seed banks and to assess the natural restoration potential of abandoned cropland in the hilly-gullied Loess Plateau. The soil seed bank was identified by the germination method with the soil samples, which were collected at four sampling times (April, August, and October 2005 and August 2006) from 12 plots abandoned 3–30 years prior to sampling. The seed bank densities of all of the samples in the 0–10 cm soil layer varied from 1,067 ± 225 to 14,967 ± 1,606 seeds m⁻². Fifty-one species (24 annual and 27 perennial species) belonging to 18 families were identified, and 39% of these species belonged to the families Compositae and Gramineae. The pioneer species Artemisia scoparia dominated the seed bank, with an average seed density of 3,722 seeds m⁻², and accounted for 74.4% of the seeds in the bank. The local dominant species (such as Lespedeza davurica, Artemisia gmelinii, Bothriochloa ischaemun and Stipa bungeana) of the later succession stages also existed at densities varying from 17 to 1, 383 seeds m⁻². The combination of soil seed bank characteristics, reproductive traits of the species, the specific landscape conditions indicates that the potential to restoring the abandoned croplands in the hilly-gullied Loess Plateau via natural re-vegetation could be substantial.     

RUNOFF AND SEDIMENT RESPONSES TO CONSERVATION PRACTICES: LOESS PLATEAU OF CHINA1

ABSTRACT: Soil erosion is the most significant threat to land productivity and environmental quality on the Loess Plateau of China. The annual total sediment load of the Yellow River is 1.6 billion tons, with about 90 percent coming from soil erosion from the Loess Plateau. To reduce soil erosion from the Loess Plateau, conservation practices, including tree planting, ridge construction between fields and around gullies, terrace and ditch construction perpendicular to the main slope, and dam construction are being implemented. An evaluation of these conservation practices is required before they are implemented at the large scale. The objective of this study is to evaluate the effectiveness of conservation practices to control runoff and sediment yield from paired watersheds in the hilly gully region of the Loess Plateau. The advantage of the paired watershed approach is its sensibility in detecting differences in runoff and sediment transport by monitoring both watersheds during two periods, an initial period with no conservation practices and a treatment period with only one watershed subjected to conservation practices. Implementation of the conservation practices resulted in (1) cumulative runoff and sediment yield that were, respectively, 25 and 38 percent less from the treatment watershed than from the control, (2) a decrease in the number of rainfall events producing runoff and sediment transport (94 in the control versus 63 in treatment), and (3) a reduction in the maximum discharge and maximum suspended sediment concentration.     

Regional and Local Scale Modeling of Stream Temperatures and Spatio-Temporal Variation in Thermal Sensitivities

Understanding variation in stream thermal regimes becomes increasingly important as the climate changes and aquatic biota approach their thermal limits. We used data from paired air and water temperature loggers to develop region-scale and stream-specific models of average daily water temperature and to explore thermal sensitivities, the slopes of air–water temperature regressions, of mostly forested streams across Maryland, USA. The region-scale stream temperature model explained nearly 90 % of the variation (root mean square error = 0.957 °C), with the mostly flat coastal plain streams having significantly higher thermal sensitivities than the steeper highlands streams with piedmont streams intermediate. Model R ² for stream-specific models was positively related to a stream’s thermal sensitivity. Both the regional and the stream-specific air–water temperature regression models benefited from including mean daily discharge from regional gaging stations, but the degree of improvement declined as a stream’s thermal sensitivity increased. Although catchment size had no relationship to thermal sensitivity, steeper streams or those with greater amounts of forest in their upstream watershed were less thermally sensitive. The subset of streams with three or more summers of temperature data exhibited a wide range of annual variation in thermal sensitivity at a site, with the variation not attributable to discharge, precipitation patterns, or physical attributes of streams or their watersheds. Our findings are a useful starting point to better understand patterns in stream thermal regimes. However, a more spatially and temporally comprehensive monitoring network should increase understanding of stream temperature variation and its controls as climatic patterns change.     

Quantifying the Effects of Conservation Practices on Soil,Water, and Nutrients in the Loess Mesa Ravine Region of the Loess Plateau,China

A large number of soil and water conservation programs have been implemented on the Loess Plateau of China since the 1950s. To comprehensively assess the merits and demerits of the conservation practices is of great importance in further supervising the conservation strategy for the Loess Plateau. This study calculates the impact factors of conservation practices on soil, water, and nutrients during the period 1954–2004 in the Nanxiaohegou Catchment, a representative catchment in the Loess Mesa Ravine Region of the Loess Plateau, China. Brief conclusions could be drawn as follows: (1) Soil erosion and nutrient loss had been greatly mitigated through various conservation practices. About half of the total transported water and 94.8 % of the total transported soil and nutrients, had been locally retained in the selected catchment. The soil retained from small watersheds do not only form large-scale fertile farmland but also safeguard the Yellow River against overflow. (2) Check dam was the most appropriate conservation practice on the Loess Plateau. In the selected catchment, more than 90 % of the retained soil and water were accomplished by the dam farmland, although the dam farmland occupied only 2.3 % of the total area of all conservation measures. Retention abilities of the characteristic conservation practices were in the following order: dam farmland > terrace farmland > forest land and grassland. (3) The conservation practices were more powerful in retaining sediment than in reducing runoff from the Loess Plateau, and the negative effects of the conservation practices on reducing water to the Yellow River were relatively slight.     

巢湖流域蒸发量特征及变化趋势研究

巢湖作为安徽省境内的一个重要湖泊，对安徽省生态环境起到一定的影响作用。蒸发量是影响生态环境的重要因子，在很多方面是该区生态环境的一个反映。采用了统计学方法，对巢湖流域15个蒸发点20年（1981-2000年）的资料进行了分析，初步探讨了巢湖流域的蒸发量空间分布特征与地势、气温、风速、降水量等因子的关系，以及蒸发量在1年内的变化特征和年际变化趋势，试图说明研究时段内人类活动对区域蒸发量的影响。研究表明，由于地形等因素的影响，巢湖流域的蒸发量空间分布不均衡，在研究时段内蒸发量大体呈上升趋势。     

PREDICTION OF STREAM TEMPERATURE IN FORESTED WATERSHEDS1

ABSTRACT: Removal of streamside vegetation changes the energy balance of a stream, and hence its temperature. A common approach to mitigating the effects of logging on stream temperature is to require establishment of buffer zones along stream corridors. A simple energy balance model is described for prediction of stream temperature in forested headwater watersheds that allows evaluation of the performance of such measures. The model is designed for application to “worst case” or maximum annual stream temperature, under low flow conditions with maximum annual solar radiation and air temperature. Low flows are estimated via a regional regression equation with independent variables readily accessible from GIS databases. Testing of the energy balance model was performed using field data for mostly forested basins on both the west and east slopes of the Cascade Mountains, and was then evaluated using the regional equations for low flow and observed maximum reach temperatures in three different east slope Cascades catchments. A series of sensitivity analyses showed that increasing the buffer width beyond 30 meters did not significantly decrease stream temperatures, and that other vegetation parameters such as leaf area index, average tree height, and to a lesser extent streamside vegetation buffer width, more strongly affected maximum stream temperatures.     

秦皇岛地区气候资源及农业气候资源特征分析

利用近50 a秦皇岛气象资料,对该地区气候资源及农业气候资源特征进行了分析总结。结果表明:秦皇岛地区年降水量650～700 mm左右,呈减少趋势。全年80%保证率的降水量为425 mm,存在供需矛盾。蒸发量较降水量明显偏多,直接决定了该地区土壤在自然状态下绝大部分时段处于干旱状态。年平均气温10℃左右,呈上升趋势。平均年太阳辐射总量为5 154 MJ/m2,太阳辐射资源较丰富。秦皇岛地区农时较长,气温稳定通过10℃期间历时192 d,可以实行短生育期作物一年二熟或套作二熟。     

PRIESTLEY‐TAYLOR ALPHA COEFFICIENT: VARIABILITY AND RELATIONSHIP TO NDVI IN ARCTIC TUNDRA LANDSCAPES1

ABSTRACT: Average daily values of the Priestley‐Taylor coefficient (a) were calculated for two eddy covariance (flux) tower sites with contrasting vegetation, soil moisture, and temperature characteristics on the North Slope of Alaska over the 1994 and 1995 growing seasons. Because variations in a have been shown to be associated with changes in vegetation, soil moisture, and meteorological conditions in Arctic ecosystems, we hypothesized that a values would be significantly different between sites. Since variations in the normalized difference vegetation index (NDVI) follow patterns of vegetation community composition and state that are largely controlled by moisture and temperature gradients on the North Slope of Alaska, we hypothesized that temporal variations in a respond to these same conditions and thus co‐vary with NDVI. Significant differences in a values were found between the two sites in 1994 under average precipitation conditions. However, in 1995, when precipitation conditions were above average, no significant difference was found. Overall, the variations in a over the two growing seasons showed little relationship to the seasonal progression of the regional NDVI. The only significant relationship was found at the drier, upland study site.