Spatio-temporal variation of soil moisture in a fixed dune at the southern edge of the Gurbantunggut Desert in Xinjiang,China

Soil moisture is critical for vegetation growth in deserts. However, detailed dataregarding the soil moisture distribution in space and time in the Gurbantunggut Desert have not yet been reported. In this study, we conducted a series ofinsitu observation experiments in a fixed sand dune at the southern edge of the GurbantunggutDesert from February 2014 to October 2016, to explore the spatio-temporal variation of soil moisture content, investigate the impact of Haloxylonammodendron (C. A. Mey.) Bungeon soil moisture content in its root zone, and examine the factors influencing the soil moisture spatial pattern. One-way analysis of variance,least significant difference testsand correlation analysis were used to analyze the data. The results revealed that the soil moisture content exhibited annual periodicity and the temporal variation of soil moisture content throughout a year could be divided into three periods, namely, a moisture-gaining period, a moisture-losing period and a moisture-stable period.According to the temporal and spatial variability, the 0-400 cm soil profile could be divided into two layers: an active layer with moderate variability and a stable layer with weak variability.The temporal variability was larger than the spatial variability in the active layer,and the mean profile soil moisture content at different slope positions displayed the trend of decreasing with increasing relative heightand mainly followed the order of interdunearea>westand east slopes>slope top.The mean profile soil moisture content in the root zone of dead H. ammodendronindividuals was significantly higher than that in the root zones of adult and young individuals, while the soil moisture content in the root zone of adult individuals was slightly higher than that in the root zone of young individuals with no significant difference.The spatial pattern of soil moisture was attributable to the combined effects of snowfall, vegetation and soil texture, whereas the effects of rainfall and evaporation were not significant. The findings may offer a foundation for the management of sandy soil moisture and vegetation restoration in arid areas.     

The efficiency of nitrogen in cattle manures when applied to a double‐annual forage cropping system

The use of cattle manure (CM) for fertilization presents challenges for optimizing nitrogen (N) use. Our work aimed to assess N efficiencies, in a 6‐year experiment with three biennial rotations of four crops: oat–sorghum (first year) and ryegrass–maize (second year) in a rainfed humid Mediterranean area of Spain. Fertilization treatments included the following: control (no N), 250 kg mineral N ha^?1 year^?1 (250MN), three CM rates (supplying 170, 250 and 500 kg N ha^?1 year^?1) and four treatments where the two lowest CM rates were complemented with either 80 or 160 kg mineral N ha^?1 year^?1. Treatments were distributed randomly in each of three blocks. Maximum dry‐matter yield (~44–49 t ha^?1 rotation^?1) was achieved in the third rotation, and only the control and the 170CM yielded significantly less. Within the limitations of the EU Nitrate Directive, the N steady state supply of 170CM always requires a complement of mineral N (80 kg N ha^?1) to maximize N agronomic efficiency. The maximum N‐fertilizer replacement value (250CM vs. 250MN) was 0·67, without significant differences between the two treatments in other N‐related efficiency indexes, which indicates that plants took advantage of residual‐N effects. Nitrogen losses by leaching in the 250CM treatment were around 5–7% of the N applied. This reinforces the sustainability of manure recycling in long cropping seasons.     

滴灌紫花苜蓿根层水分稳定同位素特征分析

为了明确滴灌紫花苜蓿根层水分运移,进一步阐明滴灌节水机理,采用液态水稳定氢氧同位素技术,分析了滴灌紫花苜蓿根层水分稳定氢氧同位素分布特征。结果表明,紫花苜蓿根层水分稳定氢氧同位素在下层富集,且随土壤剖面深度的增加同位素富集量有增加的趋势。滴灌条件下,紫花苜蓿根层发育有较多细根,可迅速而高效地利用灌溉水,灌溉后紫花苜蓿对灌溉水的利用不明确偏向于某一深度土层,根层内各土层土壤水均有利用。灌溉前土壤干旱时,滴灌紫花苜蓿以30 cm上下土层土壤水作为主要水分来源的概率较高。     

川北地形过渡带地形因子对土地利用与景观格局变化的影响

[目的]基于地形特征分析不同用地类型时空分布变化,不仅能解释土地利用时空变化规律,并能更进一步为优化土地利用结果,生态环境保护奠定基础。[方法]基于四川省北部江油市2003,2010,2018年3期遥感影像,运用土地利用转移矩阵法,分析不同用地类型之间的转化情况;接着利用地形位指数法、分布指数法,分析地形因子影响下不同用地类型分布指数变化特征;之后利用移动窗口法,探究景观格局中斑块密度与Shannon多样性指数时空变化规律;最后结合双变量空间相关性分析,分析地形因子与景观指数间的空间相关性特征。[结果](1)在2003—2010年期间,水田面积减少最多(减少面积2 238.98 hm~2),建设用地面积增加最多(面积增加3 360.36 hm~2);在2010—2018年期间,水田面积减少1 175.84 hm~2,建设用地面积增加1 614.78 hm~2;2003—2010年期间江油市土地利用的变化量整体高于2010—2018年。(2)北部山区主要由旱地转移为林草地,南部平原地区主要为水田转移为建设用地,中部丘陵区域旱地和水田相互转化强烈。(3)随时间变化,旱地和未利用地优势等级向中地形位等级靠拢;低地形位等级上建设用地、水田和水域优势度逐渐降低,并具有优势等级向较高地形位等级扩展趋势。(4)山区河流沿岸以及山地平原交汇处斑块密度与Shannon多样性指数较高,且呈线性分布;随时间变化,丘陵区域斑块密度增加,主城区附近Shannon多样性指数呈下降趋势。(5)高—高聚集区主要表现为向山地丘陵交汇处聚集;城区附近景观指数因受其他因素影响较多,导致该区域景观指数与地形位指数呈现出不显著相关性。[结论]在地形过渡带区域,不同地貌对于各类用地变化的影响在时空上存在差异性,其地形因子与景观指数的空间相关性差异明显。     

过渡地区休眠暖地型草坪草交播技术与展望

本文对我国过渡地区暖地型草坪草冬季交播技术,如交播概念、原理、草坪类型、草种选择、草种播种量及交播草坪建植与管理进行了详细介绍,以期为过渡地区建植四季长绿草坪提供技术上的支持。     

三峡库区澎溪河流域消落区土壤氮磷释放研究

通过模拟试验研究了温度和施肥对三峡库区澎溪河流域消落区冲积土、紫色土和水稻土氮磷释放的影响,估算了这3种土壤氮磷的释放量。结果表明,淹水后消落区土壤氮的释放潜力为水稻土冲积土紫色土,不同温度下消落土壤氮的释放潜力表现为20℃略高于10℃,明显高于30℃;消落区土壤间磷释放的差异因温度的不同而异,10℃时3种土壤间上覆水磷浓度相近,20℃和30℃时,土壤磷的释放潜力为冲积土紫色土水稻土,土壤磷的释放随淹水温度的提高而升高。按云阳县耕地平均施肥量(N0.21g/kg和P0.15g/kg)向消落区土壤施入氮磷肥,冲积土、紫色土和水稻土向水体释放的氮分别提高7.05～17.27,10.03～25.41,5.84～13.70倍,释放的磷分别提高1.47～4.88,4.99～16.49,1.18～3.03倍。根据澎溪河流域水温、水位变动情况及消落区土壤面积,估算出未施肥条件下澎溪河流域消落区冲积土、紫色土和水稻土的氮释放负荷为19.36,29.45,236.07t/a,磷释放负荷分别为0.49,0.94,1.91t/a。     

浅谈住宅小区边坡绿化

简述住宅小区边坡绿化技术,分析小区边坡绿化工程中存在问题,提出住宅小区边坡绿化的对策。     

降雨前后库滨带表层土壤养分研究

在官厅水库库滨地区对降雨前后库滨带表层土壤养分进行试验研究。结果表明,降雨前农田土壤总磷的含量最高,其次为湿生草本带,乔灌草带和挺水植物带则相对较低;土壤表层总氮的含量乔灌草带最高。降雨前后库滨带各区土壤表层的氮和磷大部分以颗粒态存在,库滨带各区表层颗粒直径<0.002 mm的土壤颗粒是颗粒态磷的主要载体,直径为0.02￣0.05 mm的土壤颗粒是颗粒态氮的主要载体。农田和乔灌草带表层土体截流了来水中的总磷,而挺水植物带则表现为总磷的释放,农田、乔灌草带和湿生草本带对总氮有去除作用,而以乔灌草带的去除效果最明显。     

三峡库区库岸带开发中旅游业的发展模式及其对策

三峡库区库岸带人口密集,人地矛盾十分紧张,工业基础遭到破坏,单纯发展一、二产业,投入比较大,且生态效益得不到保障.本文针对三峡库区库岸带发展的现状和存在的问题,提出了库岸带旅游业的发展模式和对策.     

棉田与相邻荒漠过渡带蜘蛛群落结构及动态分析

对新疆莎车县棉田及相邻荒漠过渡带蜘蛛种类,群落结构及动态进行了初步的研究和分析.棉田及相邻荒漠过渡带的蜘蛛有13科、36属、39种.蜘蛛在两个不同生境群落特征及多样性有明显的差异性.逍遥蛛科和蟹蛛科为两个生境中共同的优势科.荒漠过渡带蜘蛛群落的物种数、个体数量、多样性、均匀度、稳定性都高于棉田蜘蛛群落的对应特征.荒漠过渡带蜘蛛群落结构的变动对棉田内蜘蛛群落的变化有明显的影响,可以初步肯定荒漠过渡带的种库作用.