Detecting Holocene movements of the woodland–steppe ecotone in northern China using discriminant analysis

Discriminant functions link vegetation zones and surface pollen along the woodland–steppe ecotone in northern China. These links were utilised to reconstruct palaeovegetation using fossil pollen data from four lake sediment sites within the ecotone. Holocene movements of the vegetation zones were derived from the above results and were interpreted as the results of climatic, topographic and edaphic factors. This study shows that climatic change was the driving factor for ecotonal movement, but that the positions of vegetational zones were nevertheless controlled by topographical and edaphic conditions, and consequently boundaries between different vegetational zones responded individualistically. Copyright © 2001 John Wiley & Sons, Ltd.     

1960—2020年内蒙古荒漠草原连续无降水日变化特征分析

基于内蒙古荒漠草原9个气象站逐日降水和美国国家环境预报中心(National Centers for Environmental Prediction,NCEP)/美国国家大气研究中心(National Center for Atmospheric Research,NCAR)再分析资料,利用统计方法分析了该地区1960—2020年连续无降水事件变化特点及异常年份环流特征。结果表明:(1)连续无降水事件最多出现在夏季,但平均持续日数和最大持续日数在夏季最短,短期连续无降水事件和较长期降水事件相间出现是夏季降水分配格局,而其他季节则相反。(2)研究区年均无降水日数为304.1 d·a^?1,年均连续无降水事件次数为39.6次·a^?1,年均连续无降水事件平均持续日数为8.0 d·a^?1,年均最大持续日数为43.7 d·a^?1。(3)近61 a连续无降水事件3个参数变化不显著,但2005—2020年连续无降水事件次数显著增加而平均持续日数则显著减小。(4)年平均持续日数和最大持续日数均与连续无降水事件次数呈显著负相关关系,而平均持续日数和最大持续日数呈显著的正相关。(5)异常连续无降水事件期间对流层中高层有明显的温度、湿度和高度异常。     

放牧对退化草地近地面辐射的影响

随着环境变化,草原地表状态也会改变,尤其是近地面能量收支过程变化更明显。为深入理解半干旱草原地表辐射能量平衡过程对放牧的响应特征,利用内蒙古正镶白旗典型退化草原2020年生长季（6—10月）的辐射通量观测资料,对比分析了禁牧、放牧草地太阳总辐射、地表反射辐射、大气长波辐射、地表长波辐射、净辐射以及地表反照率的日变化和生长季变化规律的差异。结果表明：在生长季,太阳总辐射随着时间推进逐月递减;禁牧区的地表反射辐射总体小于放牧区;各月大气长波辐射日变化幅度很小,处于130—370 W·m^-2;禁牧、放牧条件下地表长波辐射存在明显的季节变化规律,但是二者之间的差异甚微。内蒙古典型退化草原生长季近地面辐射通量有显著单峰型日变化特征。禁牧、放牧草地地表反照率都呈现“U”型日变化规律。生长季放牧草地的反照率明显高于禁牧草地。在禁牧区,辐射分量（地表反射辐射、大气长波辐射）和植被指数（归一化差异植被指数）对净辐射的影响是正向极显著的;而地表反照率和另一辐射分量（地表长波辐射）对净辐射有显著的负向作用。在放牧区,地表反射辐射和大气长波辐射对净辐射有极显著的正向作用;而地表反照率和地表长波辐射对净辐射的作用则是负向显著的。植被状况是影响内蒙古典型退化草原近地表辐射能量收支过程的首要因子。     

不同改良措施对退化羊草（Leymus chinensis）草原的影响

 对1983年通过不同改良措施（播种羊草、耙地、围栏封育）处理过的退化羊草草原群落特征进行比较研究,结果表明：虽然经过23 a的恢复,土壤条件仍有差别,经过耙地处理土壤容重最小,含水量最高;三种改良措施的增产效果都很明显,播种羊草、耙地、围栏封育的群落地上生物量比围栏外分别提高了127.30%、146.64%、138.04%;播种羊草和耙地处理的根茎禾草所占比例较高,而围栏外和围栏封育处理的丛生禾草所占的比例较高;三种改良措施中,旱生植物的绝对生物量都低于围栏外;耙地处理后群落多样性最高,而围栏外均匀性指数最高。综上所述：经过耙地改良所产生的效果维持时间最长,而播种羊草和围栏封育改良的后效依然存在。     

内蒙古短花针茅草原种子植物区系研究

对短花针茅草原种子植物科、属、种的区系特征进行了统计分析,结果表明：①研究区共统计种子植物31科,96属,161种,并集中分布在几个大科,区系的优势现象明显;②属种比为1∶1.68,较内蒙古自治区、全国及全世界均低,物种分化程度低;③植物区系组成具有明显的温带性质,但与热带植物区系也存在一定的亲缘关系,具有过渡性;④植物区系组成以年轻成分为主,兼有古老性;⑤植物生活型特征表明本区多年生草本植物占绝对优势,表现出草原植物群落种类组成的特征,但由于该区土壤覆沙或沙质化明显,因此,灌木和半灌木种类也较多;⑥植物水分生态类群以旱生为主,非旱生也占有很大比例,具有明显的过渡性;⑦该生态系统比较脆弱,应加强保护,合理利用,实现可持续性发展。     

半干旱荒漠草原覆盖区地气测量方法研究—以内蒙古维拉斯托锌铜多金属矿床为例

半干旱荒漠草原是我国重要的地貌景观类型,由于长期受风成沙的干扰,常规化探方法在该区找矿效果不理想。本文以位于内蒙古半干旱荒漠草原覆盖区的维拉斯托锌铜多金属矿为研究对象,进行了地气测量实验。同时,为筛选地气组分中的有效指示元素,对矿石矿物进行了采样分析。结果表明该矿区矿石矿物主要为闪锌矿、黄铜矿、磁黄铁矿、毒砂,成矿元素主要为Cu、Zn、Ag、As、Fe,部分矿石中Pb、Bi、Cd、Mn、Ni含量较高。地气组分中异常元素种类与矿石成矿及伴生元素一致,且异常位置与隐伏矿体基本吻合。地气与矿石、围岩的稀土元素（REE）球粒陨石标准化配分图解显示,异常区地气REE配分特征与矿石接近,说明地气成分继承了隐伏矿体的地球化学信息。以上研究证明地气测量可作为半干旱荒漠草原覆盖区寻找隐伏锌铜多金属矿的有效手段。     

内蒙古草原生态服务演替轨迹

运用灰色系统理论及方法,基于生态学家、经济学家对内蒙古草原生态服务边际量指标体系、数理模型及相对重要性的评价和判断,创建草原生态服务边际量的数学模型系统。选取1947—2006年期间统计数据,测算过去60 a内蒙古草原生态服务的判明值,分析其基本演替轨迹。结果表明,60 a来内蒙古草原生态服务变迁过程基本遵循早期缓慢水平下降,中期快速曲线下降,后期骤然快速直线下降的演替轨迹。同时,分析了内蒙古草原生态服务“M”形波浪式下降原因的草原开垦之说。     

Rehabilitation of steppe pastures of Khakassia

We consider the current tendencies in the agricultural production of Siberia's steppe regions and the processes that are responsible for the current state and future utilization of pastures. It is shown that the ongoing reduction in livestock population, combined with a decrease in sown areas, has led to an increase in natural meadowlands, and to a widespread occurrence of post-pasture demutational successions. We outline the digression and demutation stages of steppe and sandy-steppe pastures and identify the features of their similarity and difference associated with resistance to grazing pressure. It is shown that overgrazing and underutilization decrease their natural potential. We have defined the degradation and desertification criteria for pastures, and the priorities of their utilization.     

放牧制度下荒漠草原主要植物生物量及能量分配研究

以内蒙古苏尼特右旗短花针茅荒漠草原为研究对象,通过划区轮牧与自由放牧的比较试验,从植物构件方面研究了3种主要植物种短花针茅、无芒隐子草和碱韭营养枝、生殖枝、分蘖节及其根生物量和能量分配对不同放牧制度的响应。结果表明,禁牧和划区轮牧有利于植物的地上部分生长和有性繁殖,自由放牧区短花针茅和无芒隐子草将把更多的资源和能量用于营养生长,有性生殖严重受阻,以抵御不利的生长环境;划区轮牧提高了碱韭分蘖节的生物量、短花针茅和碱韭构件能量现存量及总能量现存量。短花针茅、无芒隐子草和碱韭根的生物量、能量现存量、生物量分配比例以及根冠比能量现存量、根的能量分配比例划区轮牧区与自由放牧区均高于禁牧对照区;短花针茅、无芒隐子草和碱韭不同构件及植株整体热值划区轮牧区也高于自由放牧区。营养枝与生殖枝的生物量和能量分配没有显著的颉颃关系,但营养枝与分蘖节生物量和能量分配比例间呈显著的颉颃关系。     

Water use characteristics of coexisting sand-binding vegetation in two typical soil habitats in the desert steppe of China

Understanding the water use characteristics and water relationship of coexisting vegetation in a mixed-species plantation of trees and shrubs is crucial for the sustainable restoration of degraded arid areas. This study investigated the water use characteristic of coexisting sand-binding vegetation combinations in the sierozem habitat (Populus przewalskii Maxim namely Populus-S and Caragana liouana) and aeolian sandy soil habitats (Populus przewalskii Maxim namely Populus-A and Salix psammophila) of the desert steppe. By analysing the δ²H and δ¹⁸O isotopes in xylem, soil water, groundwater and precipitation, a Bayesian MixSIAR model was employed to quantitatively assess the water utilization characteristics of plants. Throughout the growing season, in the sierozem habitat, C. liouana exhibits the highest efficiency in utilizing soil moisture above 60 cm (53.45%) and displays adaptable water use strategies. In contrast, Populus-A predominantly relies on deep soil moisture below 60 cm plus groundwater (63.89%). In the aeolian sandy soil habitat, both Populus-A and S. psammophila similarly favour deep soil moisture below the 60 cm soil plus groundwater (66.77% and 67.60%, respectively). During the transition period from the dry to the wet seasons, although both Populus-A and S. psammophila in the aeolian sandy soil habitat shifted their water sources from deeper to shallower ones, there was considerable overlap in the water sources used by Populus-A and S. psammophila. This overlap led to competition for water resources and exacerbated the depletion of deep soil moisture in both seasons. Conversely, in the sierozem habitat, the partitioning of water sources between Populus-S and C. liouana facilitated the allocation and utilization of water resources between the two species. The findings highlight the need for species-specific consideration in water resource allocation within mixed-species plantations of trees and shrubs, which is crucial for sustainable vegetation restoration in sand-binding ecosystems.