沙丘和植被是半干旱、干旱风沙区重要的地表景观，并且风沙-植被互馈作用影响风沙蚀积格局和植被生长状况，进而引起沙丘个体形态和群体结构改变，导致景观格局与过程发生变化。本文以鄂尔多斯高原北部片状沙丘地为研究区，采用遥感监测、地面测量及空间分析相结合的方法，从景观尺度探明沙丘地斑块类型、植被分布及沙丘格局时空演变规律，从沙丘尺度定量分析沙丘形态、移动等动态特征，阐释植被引起沙丘动态变化的不同模式及其所导致的沙丘格局演化过程。在此基础上，结合气候要素和土地利用变化，探讨沙丘单体动态及群体格局变化的主要控制因素，以期深入理解剥蚀高原变化环境下的沙丘-植被作用关系及其景观效应。主要研究结论如下：

（1）研究区沙丘与植被格局时空变化显著。沙丘类型包括新月形沙丘、新月形沙丘链、抛物线形沙丘和灌丛沙丘。随着时间推移，灌丛沙堆从镶嵌分布于丘间地逐渐向外扩展，抛物线沙丘由边缘区域向沙丘地内部发展，两者扩张间断了新月形沙丘及沙丘链的连续分布。沙丘地面积随时间减小，但各类沙丘面积增减不一，其中灌丛沙堆和抛物线沙丘面积不断增大，而新月形沙丘及沙丘链面积逐渐减小。沙丘地边缘植被覆盖始终较高，并且2012年以来降水增加不仅促进自然植被在丘间地及沙丘表面定植，而且有利于人工栽植乔灌木成活，使得研究区植被覆盖度增幅较大。

（2）植被使原沙物质与气流相互作用转为风沙流与植被间的相互作用，影响近地表蚀积格局，导致沙丘自组织形式改变即沙丘格局演化。在空间尺度上，贯穿沙丘地的暂时性河流和道路隔断了沙丘顺风向连续性和沙丘间的相互作用，扰乱了沙丘自组织演变，导致沙丘格局参数自西向东无明显变化规律，并且在河流和道路分隔区内因受空间限制和植被等影响，沙丘格局参数空间变化趋势性并不明显。在时间变化上，沙丘脊线走向以NE~SW和NNE~SSW为主，但因后期西风分量增加发生逆时针偏转；因降水增多和植被盖度增大，沙丘脊线长度趋于减小、间距增大、高度降低、缺陷密度增大，沙丘格局参数之间的相关性变差。

（3）近14年来，新月形沙丘、新月形沙丘链和抛物线沙丘的移动方式一直为顺风向 迁移且方向以东为主导，其中新月形沙丘移动方向出现向北偏转。沙丘移动速率在2005~2010年、2010~2016年和2016~2019年三个时段依次递减；不同类型沙丘在各时间段内均为新月形沙丘最快，抛物线沙丘次之，新月形沙丘链最慢。沙丘在迁移过程中形态变化明显，新月形沙丘背风坡由顺风向内凹转为外凸，沙丘基部和两翼被固定，平面形状由新月形转为不规则饼状甚至呈抛物线形；抛物线沙丘轮廓由平滑变得破碎且沙丘前端趋于狭窄；新月形沙丘链顺风向凹进的弯曲度减小，连接处不断向顺风向凸出，并且植被定植在此处使各组成沙丘趋于分离状态。沙丘在迁移过程中因植被固定作用出现沙物质趋于亏损状态，大部分沙丘面积趋于减小。

（4）降水和风况是研究区沙丘动态变化的主导因素。自2012年以来，降水增加且风速减小，前者促进了自然和人工植被的定植和成活，丘间地植被向沙丘表面扩展使新月形沙丘转形为抛物线形沙丘，使新月形沙丘链在顺风向凸进处分离成若干并排的新月形沙丘而后转至抛物线形沙丘，同时导致沙丘缺陷对个数增加和脊线长度减小。丘间地植被又直接覆盖沙源使不饱和气流侵蚀丘顶，沙丘迎风坡变长、高度降低、间距增大。风速减小导致沙丘整体移动速率减慢，且有利于植被扩展；合成输沙方向随时间逐渐向北偏转，使得沙丘脊线走向整体出现逆时针转动。

Dunes and vegetation are the main landscape features in semi-arid and arid sandy areas, and the interaction between aeolian processes and vegetation affects the sand erosion-accumulation pattern and the vegetation condition, which leads to the changes of individual morphology and population structure of dunes, resulting in the changes of landscape patterns and processes. In this paper, taking the dune field on the northern Ordos Plateau as the study area, we used the remote sensing monitoring, ground measurement and spatial analysis. Combining landscape and dune scales, the temporal and spatial evolution of landscape patch types, vegetation distribution and dune pattern are explored from the former scale; the dynamic characteristics of dune morphology and movement are quantitatively analyzed, the different patterns of dune dynamic changes caused by vegetation and the dune evolution process caused by this process are explained from the latter scale. On this basis, combined with the changes of climatic elements and land use, this paper discusses the main control factors of individual dune dynamic and population pattern change, in order to deeply understand the interaction between dunes and vegetation and its landscape effect under the changing environment of the denuded plateau. The main research contents are listed as follows:

(1) The distribution pattern of dune and vegetation has significant temporal and spatial changes. Dune types include barchan dunes, barchan dune chains, parabolic dunes and nebkhas. As time goes by, nebkhas gradually expanded from the mosaic distribution among the dune field and the parabolic dunes first developed in the edge area and then appeared in the interior of the dune field. The expansion of the two has interrupted the patchy distribution of barchan dunes and dune chains. The area of dune field has decreased with time, and the area of various types of dunes has increased or decreased. Among them, the area of nebkhas and parabolic dunes increases, while the barchan dunes and dune chains decrease gradually. The vegetation coverage at the edge is always high, and the precipitation has increased significantly since 2012, which not only has promoted the colonization of natural vegetation on the interdune field and dune surface, but also has been conducive to the survival of artificially planted trees and shrubs, resulting in a large rise in vegetation coverage in the study area.

(2) Vegetation changes the interaction between original sand material and wind into the interaction between sand drift and vegetation, which is bound to affect the near surface erosion-accumulation pattern, and then leads to the change of dune self-organization form, that is, the evolution of dune pattern. On the spatial scale, the seasonal valleys and roads running through the dune field have blocked the downwind continuity of dunes and the interaction between dunes, disrupted the dunes self-organization evolution, resulting in no obvious trend of dune pattern parameters from west to east, and in each separated area of valleys and roads, the spatial change trend of dune pattern parameters is not obvious due to spacing constraints and vegetation growth. In terms of time, the trend of dune crest line is mainly NE-SW and NNE-SSW, but it gradually deflects counterclockwise due to the increase of west wind component in the later stage; Because of the increase of precipitation and vegetation coverage, the average length of crest lines decreases, the spacing increases, the height reduces and the defect density rises with time, and the correlation between dune pattern parameters becomes worse.

(3) In recent 14 years, the movement mode of typical barchan dunes, dune chains and parabolic dunes has been moving downwind, and the direction is dominated by the east, in which the movement direction of barchan dunes deflects northward with time. The dune movement rate shows a decreasing trend in the three periods of 2005-2010, 2010-2016 and 2016-2019; Movement rate of different dunes varies in different periods. Barchan dunes move the fastest, followed by parabolic dunes, and barchan dune chain is the smallest. The morphological changes have been obvious during the migration of dunes. The leeward slope of barchan dunes has changed from downwind inward concave to outward convex, the base and two horns have been fixed, and two dimensional shape has changed from crescent shape to irregular cake shape or even parabolic curve; The contour of parabolic dunes changes from smooth to broken, and the front of dunes tends to be narrow; The curvature of the barchan dune chain concave along the wind direction decreases, and the joints continue to protrude along the wind direction. Vegetation colonization makes the dunes tend to separate. During the migration of dunes, due to the fixation of vegetation, the sand material tends to be in a state of loss, and the area of most dunes tends to decrease.

(4) Precipitation and wind conditions are the dominant factors in the dynamic changes of dunes in the study area. Since 2012, the precipitation has increased and the wind speed has decreased significantly. The increase of precipitation has promoted the colonization of natural vegetation and survival of the artificial. Vegetation expands from interdune field to the dune surface, which makes the barchan dunes turn into parabolic dunes and separates the barchan dune chains into several side-by-side barchan dunes to parabolic dunes at the convex position along the wind. At the same time, it leads to the increase of the number of dune defect pairs and the decrease of crest length. Because the vegetation growing on the interdune field directly covers the sand source, the unsaturated airflow erodes the upper part of dunes, so as to carry the sand material downwind, the windward slope of dunes and spacing become longer and the height shorter. The decrease of wind speed slows down the overall movement rate of dunes and is conducive to the expansion of vegetation; The resultant direction of drift potential gradually has deflected northward with time, making the overall trend of crest line rotate counterclockwise.