Impacts of land use and plant characteristics on dried soil layers in different climatic regions on the Loess Plateau of China

A dried soil layer (DSL) formed in the soil profile is a typical indication of soil drought caused by climate change and/or poor land management. The responses of a soil to drought conditions in water-limited systems and the impacts of plant characteristics on these processes are seldom known due to the lack of comparative data on soil water content (SWC) in the soil profile. The occurrence of DSLs can interfere in the water cycle in soil-plant-atmosphere systems by preventing water interchanges between upper soil layers and groundwater. Consequently, a DSL may limit the sustainability of environmental restoration projects (e.g., revegetation, soil and water conservation, etc.) on the Loess Plateau of China and in other similar arid and semiarid regions. In this study, we investigated and compared the impacts of soil type, land use and plant characteristics within each of the three climatic regions (arid, semiarid, semihumid) of the Loess Plateau. A total of 17,906 soil samples from 382 soil profiles were collected to characterize DSLs across the Plateau. Spatial patterns of DSLs (represented by four indices: (1) DSL thickness, DSLT; (2) DSL forming depth, DSLFD; (3) mean SWC within the DSL, DSL-SWC; and (4) stable field water capacity, SFC) differed significantly among the climatic regions, emphasizing the importance of considering climatic conditions when assessing DSL variations. The impact of land use on DSLs varied among the three climatic regions. In the arid region, land use had no significant effect on DSLs but there were significant effects in the semiarid and semihumid regions (P < 0.05). The development of DSLs under trees and grasses was more severe in the semiarid region than in the semihumid region. In each climatic region, the extent of DSLs depended on the plant species (e.g., native or exotic, tree or grass) and growth ages; while only in the semiarid region, the DSL-SWC and SFC (P < 0.001) were significantly influenced by soil type. The DSL distribution pattern was related to the climatic region and the soil texture, which both followed gradients along the southeast-northwest axis of the Plateau. Optimizing land use can mediate DSL formation and development in the semiarid and semihumid regions of the Loess Plateau and in similar regions elsewhere. Understanding the dominant factors affecting DSLs at the regional scale enables scientifically based policies to be made that would alleviate the process of soil desiccation and sustain development of the economy and restoration of the natural environment. Moreover, these results can also be useful to the modeling of the regional water cycle and related eco-hydrological processes. (C) 2010 Elsevier B.V. All rights reserved.

[1]  Jeffrey D. Niemann,et al.  Analysis and estimation of soil moisture at the catchment scale using EOFs , 2007 .

[2]  L. Ji,et al.  Assessing vegetation response to drought in the northern Great Plains using vegetation and drought indices , 2003 .

[3]  Mingan Shao,et al.  Large-scale spatial variability of dried soil layers and related factors across the entire Loess Plateau of China , 2010 .

[4]  Stephen P. Hubbell,et al.  Drought sensitivity shapes species distribution patterns in tropical forests , 2007, Nature.

[5]  Jacques Gallichand,et al.  Use of the SHAW model to assess soil water recovery after apple trees in the gully region of the Loess Plateau, China , 2006 .

[6]  Jens Kattge,et al.  Temperature acclimation in a biochemical model of photosynthesis: a reanalysis of data from 36 species. , 2007, Plant, cell & environment.

[7]  A. Ritter,et al.  Geostatistical Tools for Characterizing the Spatial Variability of Soil Water Repellency Parameters in a Laurel Forest Watershed , 2006 .

[8]  R. Reedy,et al.  Ecological controls on water-cycle response to climate variability in deserts , 2005, Proceedings of the National Academy of Sciences of the United States of America.

[9]  Fulu Tao,et al.  Changes in agricultural water demands and soil moisture in China over the last half-century and their effects on agricultural production , 2003 .

[10]  Mingbin Huang,et al.  Pasture yield and soil water depletion of continuous growing alfalfa in the Loess Plateau of China , 2008 .

[11]  Thomas J. Jackson,et al.  Large scale measurements of soil moisture for validation of remotely sensed data: Georgia soil moisture experiment of 2003☆ , 2006 .

[12]  N. Pollen.  Temporal and spatial variability in root reinforcement of streambanks: Accounting for soil shear strength and moisture , 2007 .

[13]  Wang Zhi.  A study on water restoration of dry soil layers in the semi-arid area of Loess Plateau , 2003 .

[14]  E. Youngs.  Hydraulic Conductivity of Saturated Soils , 2000 .

[15]  M. Shao,et al.  The characteristics of soil water cycle and water balance on steep grassland under natural and simulated rainfall conditions in the Loess Plateau of China , 2008 .

[16]  Dean Collins,et al.  A high-quality monthly pan evaporation dataset for Australia , 2008 .

[17]  T. Zobeck,et al.  In search of sustainable agricultural systems for the Llano Estacado of the U.S. Southern High Plains , 2008 .

[18]  Kathryn Brown,et al.  Water Scarcity: Forecasting the Future With Spotty Data , 2002, Science.

[19]  Climatic changes in yield index and soil water deficit trends in China , 2000 .

[20]  Mingan Shao,et al.  Soil and water loss from the Loess Plateau in China , 2000 .

[21]  Li Jun,et al.  Effects of deep soil desiccation on artificial forestlands in different vegetation zones on the Loess Plateau of China , 2008 .

[22]  C. Field,et al.  Plants reverse warming effect on ecosystem water balance , 2003, Proceedings of the National Academy of Sciences of the United States of America.

[23]  Chulsang Yoo,et al.  EOF analysis of surface soil moisture field variability , 2004 .

[24]  A. Tsunekawa,et al.  Effects of land-cover type and topography on soil organic carbon storage on Northern Loess Plateau, China , 2010 .

[25]  R. Harper,et al.  Soil water depletion by Eucalyptus spp. integrated into dryland agricultural systems , 2006, Plant and Soil.

[26]  M. Yokozawa,et al.  Climate changes and trends in phenology and yields of field crops in China, 1981-2000 , 2006 .

[27]  T. Andrew Black,et al.  Impact of changing soil moisture distribution on net ecosystem productivity of a boreal aspen forest during and following drought , 2006 .

[28]  Li Wang,et al.  Soil desiccation for Loess soils on natural and regrown areas , 2008 .

[29]  Andrew W. Western,et al.  A terrain and data-based method for generating the spatial distribution of soil moisture , 2005 .

[30]  Jacques Gallichand,et al.  Water–yield relationships and optimal water management for winter wheat in the Loess Plateau of China , 2004, Irrigation Science.

[31]  Bojie Fu,et al.  Soil and water conservation on the Loess Plateau in China: review and perspective , 2007 .

[32]  On Problems of Vegetation Reconstruction in Yan'an Experimental Area III Significance of Native Trees in Plantation , 2000 .

[33]  K. Price,et al.  Regional vegetation die-off in response to global-change-type drought. , 2005, Proceedings of the National Academy of Sciences of the United States of America.

[34]  Z. Shangguan.  Soil desiccation occurrence and its impact on forest vegetation in the Loess Plateau of China , 2007 .

[35]  D. W. Nelson,et al.  Total Carbon, Organic Carbon, and Organic Matter , 1983, SSSA Book Series.

[36]  Zhiming Feng,et al.  Climate-induced changes in crop water balance during 1960-2001 in Northwest China , 2008 .

[37]  Liu You-ping.  Analysing the Silt Particles with the Malvern Mastersizer 2000 , 2005 .

[38]  Baoyuan Liu,et al.  Soil water depletion depth by planted vegetation on the Loess Plateau , 2009 .

[39]  D. Nepstad,et al.  Deep Soil Moisture Storage and Transpiration in Forests and Pastures of Seasonally-Dry Amazonia , 1998 .

[40]  Dang Ting-hui.  Distribution characteristic of dried soil layer in Wangdonggou Watershed in gully region of the Loess Plateau , 2003 .

[41]  R. Lark,et al.  Model‐based analysis using REML for inference from systematically sampled data on soil , 2004 .

[42]  Li Yu.  Effects of forest on water circle on the Loess Plateau , 2001 .

[43]  M. Shao,et al.  Soil desiccation in the Loess Plateau of China , 2008 .

[44]  Y. Li.  THE PROPERTIES OF WATER CYCLE IN SOIL AND THEIR EFFECT ON WATER CYCLE FOR LAND IN THE LOESS REGION , 1983 .

[45]  Li Zhanbin,et al.  Down-scale analysis for water scarcity in response to soil–water conservation on Loess Plateau of China , 2003 .

[46]  Yun-qiang Wang,et al.  A preliminary investigation of the dynamic characteristics of dried soil layers on the Loess Plateau of China , 2010 .