Responses of waterbirds to flooding in an arid region of Australia and implications for conservation

Floods are a frequent but irregular feature of Australia's dryland river catchments. We investigated changes in abundances of waterbirds in north western New South Wales with changes in wetland distribution at local, catchment and broad scales. The abundance of most functional groups of waterbirds changed in response to broad scale changes in wetland distribution, while local abundance remained highly variable. Patterns of abundance varied among functional groups of waterbirds, with some immediately responding to changes in wetland distribution and area flooded, and others apparently responding to sequences of wetting and drying. In Australia, the main conservation issue for waterbirds is water and its use across the landscape and not the spatial arrangement of any fixed array of reserves established to protect them.     

干旱区人工绿洲间作农田蒸散研究

在黑河流域中游的张掖绿洲区建立了大田环境下的春小麦和夏玉米间作农田能水平衡研究观测点,以气象观测资料为基础,采用波文比能量平衡法(BREB)和参考作物蒸散量—作物系数法(ET₀-K_c)对作物的蒸散进行了计算。结果表明：在一个完整的生长期内,利用波文比能量平衡法得到的间作作物蒸散量为688 mm,日均3.4 mm/d,用参考作物蒸散量—作物系数法得到的作物蒸散量为666 mm,日均3.3 mm/d,两种计算方法得到的蒸散量总值差别小。同期,水文平衡法计算结果为733 mm。利用波文比能量平衡法所得结果的分析表明,试验地在不同生长阶段,ET变化剧烈,生长初期、中期、末期分别为1.19、4.41和2.58 mm/d,其蒸散量分别占全年蒸散总量的7.79%、78.73%和13.48%。ET月变化显示,3月维持在一个较低水平;4月和5月剧烈增加;6月达到最大;此后的7月和8月降低,但仍维持在一个高水平;9月,随着作物进入生长末期,蒸散急剧减小。对ET日内变化分析可知,作物蒸散开始于早晨7∶00～8∶00,在14∶00左右达到最大,19∶00～20∶00趋于0 mm/d。不同生长阶段蒸散强度差异明显。     

Using integrated population modelling to quantify the implications of multiple threatening processes for a rapidly declining population

Many species of conservation concern are in decline due to threats from multiple sources. To quantify the conservation requirements of these species we need robust estimates of the impact of each threat on the rate of population decline. However, for the vast majority of species this information is lacking. Here we demonstrate the application of integrated population modelling as a means of deriving robust estimates of the impact of multiple threats for a rapidly declining koala (Phascolarctos cinereus) population in South-east Queensland, Australia. Integrated population modelling provides a basis for reducing uncertainty and bias by formally integrating information from multiple data sources into a single model. We quantify mortality rates due to threats from dog attacks, vehicle collisions and disease and the extent to which each of these mortality rates would need to be reduced, or how much habitat would need to be restored, to stop the population declining. We show that the integrated population modelling approach substantially reduces uncertainty. We also show that recovery actions that only address single threats would need to reduce those threats to implausibly low levels to recover the population. This indicates that strategies for simultaneously tackling multiple threats are necessary; a situation that is likely to be true for many of the world’s threatened species. This study provides an important framework for quantifying the conservation requirements of species undergoing declines due to multiple threats.     

Sugar beet yield response to different levels of saline irrigation water and leaching in an arid region

The main objective of this work was to evaluate the effects of saline irrigation water and leaching on the sugar beet yield components. In a field experiment in Rudasht region (Isfahan, Iran), three irrigation water salinity levels (1.6, 8.1, and 12.3 dS m^?1) and with/without leaching were applied. The experimental units comprised of a completely randomized block design, with split plot in four replications. The results indicated that the white sugar yield and alkalinity decreased by increasing the water salinity. Salts leaching significantly increased the root yield, white sugar yield, and white sugar concentration. With higher levels of water salinity molasses sugar, leaf weight, and the concentrations of Na, K, and α- amino-N in sugar beet significantly increased. Consequently, it appears that the use of drainage water in combination with fresh water could be recommended as a strategic management way to grow sugar beet in the investigated arid region.     

Assessing the degradation of saline wetlands in an arid agricultural region in Spain

A constellation of saline wetlands in the Spanish Monegros Desert is currently subjected to increasing agricultural pressure. Until now, no systematic study of their degradation status has been performed, and no comprehensive map of these wetlands has been available. Both subjects are addressed for the first time in this study. In addition, we set up a conceptual tool for assessing saline wetlands degradation that improves upon available methods within geomorphological, sedimentological or hydrological frameworks. A wetlands inventory was produced and updated using satellite data, field observations, and orthophotographs, together with the available disperse data about these wetlands' toponymy and location. The degraded landscape appearance of the surviving wetlands, mainly affected by agricultural intensification ― dumping and farming ― has been qualitatively assessed.     

The development of immunoassays to identify and quantify species source of gum arabic

Gum arabic from Acacia senegal is commonly used as an additive in foodstuffs. Adulteration of gum arabic by other gums is a potential problem for reasons of safety and quality. This study aimed to develop and evaluate the use of enzyme-linked immunosorbent assays (ELISAs) for the detection of potential adulterants of gum arabic. Indirect competitive ELISAs (IC-ELISAs) were developed using the monoclonal antibodies SY CC7 (A. senegal), SY HH3 (Acacia seyal), and SY J1A1 (Combretum erythrophyllum). All IC-ELISAs had a working range of 0.005-10 mg/mL. The antibodies used were tested using the IC-ELISAs for cross-reactivity with other Acacia species and other gums. The antibodies were very specific for their respective antigens. Significant cross-reactivity was found for SY CC7 (between A. senegal and A. melliferae) and SY J1A1 (between C. erythrophyllum and A. seyal). The IC-ELISA was adapted further to test confectionery samples for the presence of gum arabic, which was successful, although recovery rates were reduced. Both IC- and plate trapped antigen ELISA (PTA-ELISA) formats were able to distinguish an adulterated sample of gum arabic when blended with either A. seyal or C. erythrophyllum. The PTA-ELISA was more sensitive for A. seyal than the IC-ELISA, but both were equally sensitive for C. erythrophyllum. The results suggest that the antibodies SY CC7, SY HH3, and SY J1A1 could be used in combination with each other for the detection of potential adulterants of A. senegal and the detection of gum arabic in foodstuffs.     

Decomposition and soil biota after reclamation of coal mine spoils in an arid region

Summary We compared soil biota and buried wheat straw decomposition on sites subject to topsoiling plus straw mulch reclamation procedures 1–4 years prior to our study and on an unmined site. Rates of straw decomposition were highest on the unmined site. Decomposition rates were higher on the 1- and 2-year-old sites than on the 3- and 4-year-old reclaimed spoil. Microarthropod population densities and number of taxa were greater from decomposing straw on the unmined site and lowest from straw on the 1- and 2-year-old areas. Soil bacteria, fungi, and protozoan populations on buried straw on the oldest reclaimed sites were generally equal to those on the unmined area. Nematode populations on buried straw in the unmined site and 1- and 2-year-old reclaimed sites were similar. Populations of denitrifying bacteria were larger on recently reclaimed sites than on 3- and 4-year-old sites. Decomposition and nitrogen mineralization varied as a function of the diversity and abundance of soil microarthropods. Soil microfauna can serve as an index of soil development in a disturbed arid soil.     

Variation in soil chemical properties along toposequences in an arid region of the Levant

Detailed characterization of soils and their variation along different topography positions has not been investigated in depth for Mediterranean arid regions. There is a need to accurately understand the variation and the spatial distribution of soil properties within dry region of the Levant. Such understanding is required to optimize the use and management of scarce land and water resources. The objective of this study was to examine the effect of hillslope characteristics on the variation of selected soil chemical properties in an arid Mediterranean climate. At each of five selected transects four sites were chosen to represent four different topographic positions: summit, shoulder, backslope and toeslope. A soil profile was examined at each site and a representative sample from each horizon was withdrawn for chemical analyses. The analyses indicated that generally, the carbonate contents of the surface horizons decreased from higher to lower positions of the toposequence, the carbonate content increased with depth for profiles occupying the lower positions. This suggests more intense leaching within soil at lower positions. The effect of steepness and curvature on controlling the variation of soil properties was obvious at the summit and shoulder positions. Leaching process seems to hinder the effect of steepness and curvature for soils at lower positions. Lower positions receive runoff water and organic matter from upper positions, which complicate the relationship between landform shape and organic matter content. Continuous tillage resulted in lower organic matter contents for soils at lower positions. Higher pH values were reported for soils down along the transect due to the movement of soil material from upper hillslope positions. Electrical conductivity, exchangeable calcium and potassium contents decreased downslope due to higher moisture accumulation. However, no obvious relationship was found between the variation of pH or EC in one hand and the variation of steepness and curvature on the other. Potassium content was variable due to its greater mobility. The analyses indicated that variation in the soil CEC is governed by two factors: the leaching pattern, which is controlled by hillslope position, and the accumulation of Eolian carbonates at the soil surface. The distribution of iron oxides and types of clay minerals indicated more weathering in a descending direction and with soil depth, which is attributed to higher availability of soil moisture along the same direction. These relationships suggested systematic variation of chemical properties along toposequences in this arid environment.     

Lithogenic and anthropogenic impacts on soil surface magnetic susceptibility in an arid region of Central Iran

In this study, natural and anthropogenic factors affecting the spatial distribution of topsoil mass magnetic susceptibility (χlf) were investigated in an arid region in Isfahan province, central Iran. A total of 100 surface (0–5 cm) soil samples were collected, and the χlf value of the soil samples was measured. High values of χlf in the east and northeast parts of the area indicated the occurrence of hilly igneous rocks and pediment geomorphic surface, enriched by ferrimagnetic minerals. In order to investigate the effects of human activities, multivariate geostatistics was applied to the results on the concentrations of eight heavy metals in surface soil samples. The results indicated that the spatial variability of second factor extracted by factor analysis, with high contribution of Zn, Pb and Cu, was well in agreement with the distribution of urban and industrial sites. This implied that magnetic particles accompanying the heavy metal emissions have increased χlf in the topsoil of the west of the area studied. Multiple linear regression analysis of χlf with studied factors revealed that the developed model explained about 64% of total variability in χlf in the studied area; and geology was identified as the most important controlling factor.     

干旱区膜下滴灌制度对土壤盐分分布和棉花产量的影响

土壤盐渍化在干旱区越来越加重。因此在干旱区盐碱粉砂壤土中应用滴灌时,如何制定合理的灌溉制度使得灌溉水对土壤盐分的淋洗是一个关键的科学问题。本文就此问题,2007～2009年进行了3年的膜下滴灌土壤水盐运移的试验研究。结果表明,在棉花生长阶段,随着灌溉定额的增加,土壤盐分峰值位呈现下移的趋势。当灌溉定额从DIA(3 000 m3 hm-2)增加至1.6 DIA时,盐分峰值位置向垂直方向从35 cm下移至65 cm。滴灌结束之后,土壤盐分峰值的下移顺序为1.6 DIA>1.4 DIA>1.2 DIA>DIA。随着滴头流量的增加,在一定的滴水强度范围之内,土壤盐分峰值位置呈现下移的趋势,当滴头流量进一步增加时,土壤孔隙的入渗能力变得小于滴头流量,致使土壤盐分下移受水分运动的影响。灌溉结束之后土壤盐分峰值的下移顺序为2.6 L h-1>2.2 L h-1>1.8 L h-1>3.2 L h-1。在时间尺度上,灌溉结束时,随着时间的推移,土壤盐分呈现从深层到地表和从膜下到膜间的双向迁移趋势。随着灌溉定额或滴头流量的增加,棉花产量也呈现先增加后减少的趋势。由此可见,无论是水分亏缺或者过量灌溉均会降低棉花产量,同时过小或过大的滴头流量也不利于增加棉花产量。因此在干旱区的粉砂壤土中进行膜下滴灌时,要使棉花产量达到较高值,应尽量采用2.6 L h-1的滴头流量和1.4 DIA的灌溉定额处理为宜。     

西北旱区石羊河流域作物耗水点面尺度转化方法的研究

基于DEM与GIS空间分析功能研究了石羊河流域主要农作物春小麦需水量ET_c的时空分异规律。根据8个气象站近50年气象资料,应用1998年FAO推荐的Penman-Monteith公式计算参考作物蒸发蒸腾量ET₀,由收集到的春小麦需水量试验资料获得多年平均作物系数K_c。近50年来流域上游的古浪、天祝春小麦全生育期ET_c呈微弱的增加趋势,中游的凉州区表现出极显著的减少趋势,其他站减少趋势不显著。确立了ET_c与海拔高度、纬度、坡向的多元回归关系,借助Arcview3.3、ArcGIS9.0与Visual Basic6.0软件实现了春小麦ET_c的空间尺度转换,并分析了石羊河流域25%、50%、75%三个不同水文年春小麦ET_c的空间变异情况。石羊河流域春小麦ET_c由山区向绿洲平原递增,多年平均值为270～591 mm。估计值与计算值相差在11.1%以内。     

Comparison of three evapotranspiration models to Bowen ratio-energy balance method for a vineyard in an arid desert region of northwest China

The accurate determination of vineyard evapotranspiration (ET) in the arid desert region of northwest China is important for allocating irrigation water and improving water use efficiency. Taken a vineyard at the Shiyang river basin of the Hexi corridor of Gansu Province as an example, this study evaluated the applicability of the Bowen ratio-energy balance (BREB) method in the arid desert region of northwest China, simulated the variation of vineyard ET by Penman–Monteith (P–M), Shuttle–Wallace (S–W) and Clumping (C) models in this region and compared the estimated ET by the three models with the measured ET by the BREB. Results indicated that the BREB could provide the accurate measurement of vineyard ET from the arid desert region when the Bowen ratio instrument with higher accuracy was correctly installed. Generally, the variation of the estimated ET from P–M, S–W and C models were similar to that of the measured ET by the BREB method. However, the P–M model overestimated the ET significantly; the estimated ET from the S–W and C models, especially from the C model was approximately equal to the measured ET by the BREB. After a rainfall, the performances of the S–W and C models were also good. Therefore, among the three models, the C model was the optimal model in simulating the vineyard ET in the arid region of northwest China. However, after a frost, the C model significantly overestimated the evapotranspiration because the canopy resistance did not fully reflect the dramatic decrease of grapevine transpiration.     

不同种植模式下旱地春玉米产量对降雨和气温变化的响应

为了探究旱区气候变化及主要气象因子对不同种植模式下玉米产量的影响,该研究对AquaCrop模型玉米参数进行校准和验证,并在35a历史气象数据的基础上设计不同气温和降雨梯度,利用模拟的方法分析不同情景下玉米产量变化趋势。结果表明:AquaCrop模型在试验点模拟精度较高,3种种植模式下实测与模拟产量的均方根误差为245.34~745.10 kg/hm~2,标准均方根误差为6.94%~9.49%。在设定范围内(降雨降低15%~升高15%,气温降低1.5℃~升高1.5℃),随气温和降雨升高,3种种植模式下产量波动均呈减小趋势,其中全膜双垄沟播下产量波动最小,平均产量曲线斜率为0.083 4,适应气候变化能力较强。在A3B3(温度升高1.5℃、降雨提高15%)情景下产量均达到最大,相比历史气候,露地、单垄、全膜双垄沟播分别平均增产13.45%、11.57%、17.67%。气温对3种模式下产量均有极显著影响,降雨对露地种植产量影响为极显著,而对单垄和全膜双垄沟播产量影响显著。该研究对气候变化下作物产量预测、风险评估及制定相关管理措施提供参考。     

干旱地区有机肥料腐解及腐殖化系数的研究

新疆农田主要施用的三种秸秆肥和三种厩肥,在一年内的腐解率分别平均为71 84%和43 22%,绿肥(油葵)腐解率高达95%～97%;有机肥料的腐殖化系数在18%～27%,平均21 5%;土壤有机质年矿化率一般在4%～12%,平均5%～6%。表明土壤有机质矿化率较高,而有机肥料的腐殖化系数较低,这是新疆农田土壤有机质含量难于提高的两个很重要的原因。     

Ecological and health risk assessment of trace elements in surface soil in an arid region of Xin Jiang,China

Journal of Soils and Sediments - Trace element pollution in soil has become an increasingly common issue and potentially harms the environment and human health. In this study, the contamination...     

Use of geochemical fingerprints to trace sediment sources in an agricultural catchment of Argentina

Soil erosion and associated sediment redistribution are key environmental problems in Central Argentina. Specific land uses and management practices, such as intensive grazing and crop cultivation, are considered to be significantly driving and accelerating these processes. This research focuses on the identification of suitable soil tracers from hot spots of land degradation and sediment fate in an agricultural catchment of central Argentina with erodible loess soils. Using Energy Dispersive X-Ray Fluorescence (EDXRF), elemental concentrations were determined and later used as soil tracers for geochemical characterization. The best set of tracers were identified using two artificial mixtures composed of known proportions of soil sources collected from different lands having contrasting soil uses. Barium, calcium, iron, phosphorus, and titanium were identified for obtaining the best suitable reconstruction of source proportions in the laboratory-prepared artificial mixtures. Then, these elements, as well as the total organic carbon, were applied for pinpointing critical hot spots of erosion within the studied catchment. Feedlots were identified to be the main source of sediments, river banks and dirt roads together are the second most important source. This investigation provides key information for optimizing soil conservation strategies and selecting land management practices and land uses which do not generate great contribution of sediment, preventing pollution of the waterways of the region.     

干旱区滴灌玉米出苗期施用启动磷肥的增产效应

【目的】目前滴灌施肥技术下,玉米在苗期容易缺肥。研究腐植酸和柠檬酸与磷肥配合作为启动肥对玉米苗期养分吸收的影响,为提高启动磷肥的施用效果提供理论和技术支撑。【方法】于2020和2021年,在新疆石河子市进行滴灌玉米田间试验。试验设全生育期不施磷肥对照(CK);全部氮磷钾肥分8次从拔节期开始滴灌施肥(CF);30%氮磷钾肥做启动肥(DSF);30%氮磷钾结合腐植酸做启动肥(HSF);30%氮磷钾肥结合柠檬酸做启动肥(CSF),3种启动肥处理其余的70%的肥料分8次从拔节期起滴施,共5个处理。在苗期测定滴灌玉米总根长,地上部和地下部干物质累积及磷累积吸收量;在拔节期、抽雄期和成熟期测定玉米光合特性、干物质累积及磷累积吸收量;在成熟期测定玉米产量。【结果】连续两年数据显示,DSF、HSF和CSF处理较CF处理显著增加了苗期玉米总根长、根长密度和根重密度,不同启动磷肥处理促进苗期玉米根系生长,表现为CSF>HSF>DSF。2020年,相比CF处理,DSF、HSF和CSF处理玉米产量分别增加了4.60%、8.77%和9.82%,磷表观利用率分别提升了3.21、9.13和7.66个百分...     

Using lipid analysis and hyphal length to quantify AM and saprotrophic fungal abundance along a soil chronosequence

We evaluate the use of signature fatty acids and direct hyphal counts as tools to detect and quantify arbuscular mycorrhizal (AM) and saprotrophic fungal (SF) biomass in three Hawaiian soils along a natural soil fertility gradient. Phospholipids16:1ω5c and 18:2ω6,9c were used as an index of AM and saprotrophic fungal biomass, respectively. Both phospholipid analysis and hyphal length indicated that the biomass of AMF was greatest at the highest fertility site, and lowest where phosphorus limits plant growth. Saprotrophic fungal biomass did not vary. Hyphal length counts appeared to under-estimate SF abundance, while the phospholipid AMF:SF ratio was in line with expectations. This study indicates that phospholipids may be a valuable and reliable tool for studying the abundance, distribution, and interactions between AM and saprotrophic fungi in soil.     

新疆干旱区湿地景观格局遥感动态监测与时空变异

为了解和掌握全球变化环境下中国干旱区湿地的分布现状、变化过程和时空格局特征,该文通过多源遥感技术手段,采用面向对象分类方法和目视解译相结合,完成了干旱区湿地信息的多期监测,实现了新疆地区2000、2005和2010年的湿地分布制图,并利用动态度模型和地统计方法计算了近10 a时空变化情况,分析了湿地变化的时空特征。研究结果表明:1)近10 a来全疆干旱区湿地约增加了10.1%,2010年新疆湿地总面积达到22 438 km2,较2000年约增加了2 065 km2;2)在类型构成上,2010年河流湿地、湖泊湿地、沼泽湿地和人工湿地所占比例分别为42.73%、29.43%、17.98%、8.92%和0.94%;3)在空间分布上,南北疆呈现不均衡,南疆湿地约占总体的76%,北疆湿地仅占24%;主要分布在塔里木流域,以河流湿地为主,空间分布差异显著;4)新疆湿地面积总体上呈增多的趋势,不同类型的湿地面积变化幅度差异较大。沼泽湿地和人工湿地的动态度分别为:2.58%、2.43%,河流湿地与湖泊湿地的动态度为:0.59%、0.43%;净增量最大的是沼泽湿地和河流湿地,分别增加了827.92和531.86 km2,占湿地净增量的65.85%。在变化原因上,全球变暖、新疆区域气温升高和降水增多是湿地近年来增加的主要原因;人类活动的干扰,加剧了湿地变化的复杂性和空间差异性。研究结果可为区域生态环境变化研究以及湿地资源的保护规划提供数据支持和结论参考。