毛乌素沙地南缘沙区不同类型地表水分特征曲线测定与分析

为探明不同类型地表(裸沙、浅灰色藻类结皮、黑褐色藻类结皮和藓类结皮)的持水性能,采用砂性漏斗法对毛乌素沙地南缘沙区不同类型地表表层[(0~5)cm]土壤水分特征曲线进行了测定;并用v-G模型进行拟合。结果表明:1不同类型地表持水性能有差异,持水性能由弱到强依次是裸沙、浅灰色藻类结皮、黑褐色藻类结皮和藓类结皮,不同类型生物结皮样地持水性能分别是裸沙的1.3、1.7和2倍,不同类型生物结皮的持水性随结皮的发育呈增加的趋势;2不同类型地表土壤水分特征曲线呈"S"型分布,不同类型地表吸湿过程较脱湿过程具有显著的滞后性;3用v-G模型对测定结果进行拟合,拟合系数均小于0.009,拟合度高,表明该模型适用于此地区土壤,可用于模拟水分特征曲线;研究结果有助于全面了解生物结皮的水文效应,为受损系统的生态修复过程具有现实意义。     

Arbuscular mycorrhizal fungi associated with the clonal plants in Mu Us sandland of China

Clonal plants in Mu Us sandland change the sandy enviroment. The clonal plant is a kind of resource in restoration of the Mu Us sandy landscape. Soil samples at depth of 50 cm in the rhizosphere of the clonal plants were collected in 4 replicates at each location and divided into sections corresponding to 0—10, 10—20, 20—30, 30—40 and 40—50 cm depths in two representative sites from north to south in Mu Us sandland, northwestern China, in July 2005. Clonal plants included Psammochloa villosa and Hedysarum laeve. The colonization and ecological distribution of arbuscular mycorrhizal (AM) fungi were investigated in the rhizosphere of clonal plants in Mu Us sandland. The results showed that the clonal plants established well symbiosis with AM fungi; AM fungal species and spatial distribution were significantly related with the host plants and soil factors. Of 16 AM fungal taxa in three genera isolated and identified, Glomus multicaule was only observed in the rhizosphere of Psammochloa villosa; Glomus aggregatum, Glomus hydembadensis, Glomus constrictum and Acaulospora rehmii only appeared in the rhizosphere of Hedysarum leave. The depth of soil layers observably affected the spore density and the frequency of colonization (%F). The maximal %F and spore density occurred in the 10—20 cm layer at the site of Ordos Sandy Land Ecological Station, but which occurred in the 0—10 cm layer in Shanxi Yulin Rare Sandy-plants Conversation Field. AM fungal status and colonization might be used to monitor desertification and soil degradation.     

Arbuscular mycorrhizal fungi associated with the clonal plants in Mu Us sandland of China

Clonal plants in Mu Us sandland change the sandy enviroment. The clonal plant is a kind of resource in restoration of the Mu Us sandy landscape. Soil samples at depth of 50 cm in the rhizosphere of the clonal plants were collected in 4 replicates at each location and divided into sections corresponding to 0—10, 10—20, 20—30, 30—40 and 40—50 cm depths in two representative sites from north to south in Mu Us sandland, northwestern China, in July 2005. Clonal plants included Psammochloa villosa and Hedysarum leave. The colonization and ecological distribution of arbuscular mycorrhizal (AM) fungi were investigated in the rhizosphere of clonal plants in Mu Us sandland. The results showed that the clonal plants established well symbiosis with AM fungi; AM fungal species and spatial distribution were significantly related with the host plants and soil factors. Of 16 AM fungal taxa in three genera isolated and identified, Glomus multicaule was only observed in the rhizosphere of Psammochloa villosa; Glomus aggregatum, Glomus hydembadensis, Glomus constrictum and Acaulospora rehmii only appeared in the rhizosphere of Hedysarum leave. The depth of soil layers observably affected the spore density and the frequency of colonization (%F). The maximal %F and spore density occurred in the 10—20 cm layer at the site of Ordos Sandy Land Ecological Station, but which occurred in the 0—10 cm layer in Shanxi Yulin Rare Sandy-plants Conversation Field. AM fungal status and colonization might be used to monitor desertification and soil degradation.     

Validating a dust production model by field experiment in Mu Us Desert, China

It is essential for validation and improvement of a dust production model to perform field observations on dust emissions. The dust production model (DPM model) consists of two physically explicit sub-models, namely saltation model [1, 2] (eq. (1)) and sandblasting model [3] (eqs. (2) and (3)). Fh is saltation flux, E is fraction of erodible surface, C is a dimensional constant, ρa is air density, g is gravitational acceleration, U* is the wind friction velocity, Ut*(Dp) is threshold frict…     

毛乌素沙地地貌发育规律及对人类生存环境的影响

根据毛乌素沙地东南部若干第四纪剖面,分析了沙地生成、发育的过程,认为沙地地貌的发育经历了湖泊——风成砂——湖沼(黑垆土)——风成砂的旋回过程,并与整个自然环境的变化相对应,使人类生存环境形成了脆弱、多灾、易灾的特点。     

Characteristics of surface runoff in a sandy area in southern Mu Us sandy land

To better understand the key role of biological soil crusts (BSCs) in redistribution processes of limited water resources in semi-arid sandy ecosystems, surface runoff over BSCs in a sandy area in the southern Mu Us sandy area was observed in this study. The results indicated that runoff occurred twice among six rainfall events during the experimental period. Runoff yields varied among types of BSCs, and that they increased in the following order: light algae crusts, dark algae crusts and moss crusts. These findings showed that runoff yields were increasing with the development of BSCs. The percentage of runoff in individual rainfall events increased from light algae crusts to moss crusts, which indicated that the redistribution ratios of different types of BSCs differed. Surface runoff of BSCs may be influenced by rainfall, rain intensity, degree of water saturation of the BSCs before the rain and degree of development of BSCs. Formation of BSCs on the surface of sand dunes changed the spatial distribution pattern of water in this semi-arid sandy ecosystem, which increased the heterogeneity of resources such as water and nutrients. Therefore, making appropriate disturbances of BSCs during storm season is beneficial to maintaining the balance of natural resources in the semi-arid sandy ecosystem.     

Developing stages and causes of desertification in the Mu Us sandland

Based on historical aerial photography of three periods and together with field investigation, the status of desertification development after the 1950s in the Mu Us sandland was analyzed, the difference of the desertification developing speed at two stages was compared, and its possible causes were explored. The results show that the developing speed of desertification from the late 1970s to the early 1990s is apparently slowed down, compared with that from the late 1950s to the late 1970s and there exists an obvious recovery trend at the second stage. The difference between the two stages accounts for severely over-reclaiming, over-grazing and unrestricted cutting during the first stage, which are the main causes of desertification development in the semi-arid steppe and arid desert steppe areas.     

毛乌素沙地中国沙棘无性系种群林缘扩散规律

以样地调查资料为基础。分析了中国沙棘无性系种群的林缘扩散规律及其生态学意义。结果表明,中国沙棘通过无性系生长向林缘扩散形成“阶梯式”同龄斑块镶嵌体系。群落依靠该体系不断向前移动或者同龄斑声之间的交替更新来维持和恢复其稳定性。同时,林缘扩散种群具有密度大、生产力高等特征,但其生物量积累和自然稀疏过程与有性植物种群具有相同的规律。     

科尔沁沙地范围确定及风沙地貌特征研究

科尔沁沙地范围的界定,目前尚未达成共识.本文利用Landsat8OLI影像和ASTER GDEM数据,采用水系流域分割方法,划定科尔沁沙地的自然地理范围.并提取了各类沙丘分布信息,对沙丘格局特征和形态示量做了定量研究.结果表明,科尔沁沙地面积64 387.22km2,风沙覆盖面积37 381.00km2.风沙地貌分布及格局具有一定规律性,沙丘类型自西向东、自南向北趋于简单,并主要分布在西辽河干、支流沿岸的冲积平原上,不同河谷形态、走向其两侧沙丘发育呈现差异性,河流对沙地发育演化及维持其平衡态具有重要意义.     

表土粒度特征对风蚀荒漠化的响应

 为了阐明风蚀对表土粒度特征的影响,采用时空替代法选择毛乌素沙地5 种不同利用类型的土地（草地、新垦耕地、7~8 年耕地、>20 年耕地、沙丘）,以其表层土壤（0~1、1~2、2~3、3~4、4~5 cm）为研究对象,通过野外实地采样和室内实验相结合的方法进行土壤机械组成与土壤颗粒分形分析。结果表明：1）5 个样地表层土壤机械组成均以细沙质量分数最高,为62.52%~80.40%,粗沙质量分数最低,仅为0.16%~0.43%,不同粒级土壤颗粒的质量分数高低排序为：细沙>中沙>极细沙+粉沙>粗沙,说明研究区土壤基质组成以细沙为主,沙物质分选好;2）5 个样地不同采样深度上的粗沙和中沙质量分数从大到小为0~1 cm>1~2 cm>2~3 cm>3~4 cm>4~5 cm;细沙质量分数各层次之间差异不显著（P=0.4558）,以0~1 cm 层的质量分数最低;极细沙+粉沙的质量分数0~1 cm和1~2 cm层显著低于其他3层（P=0.0126）,表明从草地到沙丘的演化是一个主要以极细沙+粉沙质量分数减少的风蚀荒漠化过程;3）土壤颗粒分形维数与极细沙+粉沙的质量分数呈极显著正相关关系,D=0.3661lnx+1.3409（P<0.0001）。5个样地的土壤颗粒分形维数存在极显著差异（P<0.0001）,从大到小依次为：草地（2.579）、新垦耕地（2.479）、7~8年耕地（2.361）、>20年耕地（2.100）、沙丘（1.716）。因此认为土壤颗粒分形维数可替代土壤机械组成来表征土地风蚀荒漠化的程度。     

新疆和田地区土地沙漠化原因及其对策分析

土地沙漠化是全世界共同面临的一个重大的环境与社会经济问题.新疆和田地区自然条件恶劣,生态环境脆弱,环境灾害多发,土地沙漠化不断加剧,沙进人退的形势日趋严峻,严重制约着当地经济和社会的可持续发展.文章从多个侧面阐述了该地区土地沙漠化的原因,并提出了相应的对策和建议.     

水肥状况对沙地小麦灌浆的影响

通过对不同品种、不同水肥条件和不同砂土类型的小麦子粒形成及灌浆强度的测定表明，沙地小麦灌浆主要良现为灌浆期短(一般15-17天)，开花至成熟持续时间短(30天左右)，千粒重低，灌浆强度较高的特点。千粒重与旗叶单位面积干重、茎秆上部三个节间单位面积干重均呈极显著负相关，与倒二叶、倒三叶相关不显著。土壤水分状况是影响沙地小麦灌浆的重要因素，增施有机肥，可减少灌水，提高灌浆强度，延长灌浆时间。     

近15年来呼伦贝尔沙地土地沙漠化发展及其驱动力

基于2001—2015年MODIS NDVI遥感数据反演了呼伦贝尔沙地近15年来植被覆盖度和沙漠化土地的空间格局与变化.结果表明:2001年以来呼伦贝尔沙地土地沙漠化总体有所减弱,但年际变化显著.其中:2001—2007年沙漠化土地以扩张为主;2007—2013年随植被覆盖缓慢恢复,沙漠化逐渐逆转;2013—2015年沙漠化有所加剧.降水量年际变化是该区沙漠化逆转或加剧最重要的驱动力.在气候变化背景下,未来几十年内该区沙漠化具有正过程发展趋势.     

毛乌素沙地中国沙棘无性系生长的表型可塑性

无性系植物可通过自身的表型可塑性调节适应不同的环境资源供应水平.在环境条件相同的情况下,以典型的无性系植物中国沙棘为对象,采用跟踪挖掘和样方相结合的方法,调查分析中国沙棘无性系生长差异.结果表明:中国沙棘无性系之间的生长特征和形态特征均存在明显差异,具体表现在子株数量和子株大小、子株数量散布格局和子株大小散布格局,以及无性系子株群结构等方面.此外,子株地径与母株地径之间存在显著的正相关关系.     

呼伦贝尔沙地不同树龄樟子松对气候的响应

【目的】对呼伦贝尔沙地不同树龄樟子松年表的特点及其径向生长与气候因子的关系进行探讨,分析不同树龄樟子松对气候响应的差异性,为该地区沙地樟子松的年轮气候学和不同树龄组沙地樟子松的经营管理提供一定的理论依据。【方法】采用COFECHA、ARSTAN程序建立标准年表,利用呼伦贝尔沙地两个样地的樟子松(Pinus sylvestris var. mongolica)样芯,划分成3个不同树龄组,运用DendroClim2002进行标准年表与气候因子响应分析。【结果】从不同树龄组的年表统计特征值发现,平均敏感度(MS)相差不大,都含有较高的气候信号。不同树龄组的一阶自相关(AC₁)是逐渐递增的,不同树龄组的信噪比(SNR)和样本代表性(EPS)都以中龄组最高,老龄组最低。从响应分析的结果来看,低龄组对气温的敏感性最高,老龄组对降水的敏感性最强。中龄组受前一年6月、7月的降水和最低气温共同影响显著,与6月的平均气温也呈显著负响应,同时与前一年12月的降水呈显著负响应。【结论】呼伦贝尔沙地不同树龄组樟子松的径向生长受气候条件的响应不尽相同,老龄组树木的生长对前一年12月的降水最为敏感,达到响应系数的最高值,低龄组和中龄组的生长都出现了与6月气温之间的负响应关系,这些是否与全球变暖、大兴安岭地区气候暖干化趋势加强有关,还需要进一步的研究。     

夏季高寒沙地乌柳林的水分来源

【目的】共和盆地位于青藏高原的半干旱区,属于典型的高寒沙地,是青海省土地荒漠化最严重的区域之一。乌柳是当地退化草地恢复的主要树种,乌柳林的稳定性是其可持续管理的关键。研究夏季乌柳林的水分来源以分析它们在半干旱区能否维持稳定性。【方法】利用稳定氢、氧同位素技术研究了夏季4个林龄乌柳林的水分来源,比较乌柳林的木质部水分与各潜在水源的稳定氢、氧同位素值,确定7月乌柳林主要利用的水源。【结果】不同林龄乌柳林可利用不同深度的土壤水或地下水。其中,2年生乌柳林主要利用地表下25 cm的土壤水,占总水源的75.5%; 10年生乌柳林主要利用地表下25～75 cm的土壤水和地下水,占总水源的73.9%; 20年生乌柳林主要利用地表下50～75 cm的土壤水和地下水,占总水源的67.7%; 30 年生乌柳林主要利用地表下25 cm的土壤水和地下水,占总水源的69.6%。随着林龄的增加(从10 a到30 a),乌柳林对地下水的依赖性逐渐增强。【结论】乌柳林通过调整水分利用策略来适应共和盆地的半干旱气候。利用稳定的深层土壤水和地下水有助于长期维持乌柳林稳定性,建议将乌柳作为高寒沙地和其他半干旱地区退化植被恢复的主要树种推广。     

科尔沁沙地生物与工程结合的固沙措施与效果

应用生物与工程措施对科尔沁沙地西部流动沙丘进行植被恢复,并通过沙丘监测和植被调查来评价流沙固定和恢复效果.1.0×1.0m的草方格结合适宜的固沙植物,能达到最佳的防风固沙效果.流动沙丘经人工措施固定后,随固定年限的增加,土壤水源涵养能力逐步提高,土壤中的有效养分如全C、有效K、碱解N和有效P等指标显著提高,土壤化学性质得到明显改善.植被盖度明显提高,植物生态系统趋于相对稳定的状态.     

科尔沁沙地不同演替阶段植被特征及固沙作用

为了解不同措施对退化生态系统植被恢复的作用,采用空间代替时间的方法研究了科尔沁沙地不同演替阶段的植被变化特征,同时探讨了植被的抗风蚀及固沙作用。结果表明,人工植被恢复措施可有效提高沙丘的植被盖度和物种丰富度,多年生植物逐渐取代了一年生植物：沙丘与草场的植被相似性较差：植被的抗风蚀能力随植被盖度的增加而增加。根据目前植被的发展现状,对不同演替阶段的植被保护、管理和恢复提供了科学的指导意见。     

Landscape and land use in southern Hainan Island, China

According to the landscape/land use relation of southern Hainan Island, four main zones are considered: the mountain and high hill zone, the inner coastal zone, the shoreline zone and the marine zone. The economic boom has led to an increase in urbanization and development of tourism, at times harming the local environment.