Modeling the Potential of the Northern China Forest Shelterbelt in Improving Hydroclimate Conditions¹

Abstract

The forest shelterbelt (afforestation) project in northern China is the most significant ecosystem project initiated in China during the past three decades. It aims to improve and conserve the ecological environment in the project areas. The tree belt stands along the southern edge of the sandy lands, nearly paralleling to the Great Wall. This study used a regional climate model to simulate the potential of improving regional hydroclimate conditions resulting from the afforestation project. Two simulations with preafforestation and postafforestation land cover were performed over East Asia from January 1987 to February 1988. The model resolution is 60 km. The differences between the two simulations suggest that the northern China forest shelterbelt project is likely to improve overall hydroclimate conditions by increasing precipitation, relative humidity, and soil moisture, and by reducing prevailing winds and air temperature. The effects are more significant in spring and summer than fall and winter. Changes in many hydrologic properties (e.g., evapotranspiration, soil moisture, and water yield), however, differ between the dry Northeast China and the moist Northeast China. The hydroclimate effects are also found in the surrounding areas, featured by noticeably moister conditions in the area south of the afforestation project. The results imply that the shelterbelt project would reduce water yield in afforested Northwest and North China during spring, but increase water yield in the afforested Northeast China as well as in the southern surrounding area, offset some greenhouse effects, and reduce the severity of dust storms. Possible improvements of this study by using actual afforestation data, modeling with higher resolution, longer integration and more detailed processes, and analyzing the physical mechanisms are discussed.

Contribution of soil moisture feedback to hydroclimatic variability

“…It could also permit better targeting of alterations to the land surface (e.g. forestation of desert boundaries, Liu et al, 2008;Ornstein et al, 2009) to achieve desirable climate consequences.…”

A numerical study on hydrological impacts of forest restoration in the southern United States

“…Many studies have provided simulation and measurement evidence of the importance of landcover change to regional hydrology (Pielke and Avissar, 1990;Shukla et al, 1990;Dickinson et al, 1993;Xue, 1996;Bonan, 1997;Liu et al, 2008). Latent heat energy is necessary for evapotranspiration.…”

“…Thus, the southern United States is likely comparable to the Amazon in the hydrologic and climatic impacts of landscape change. This is different from a large-scale forest restoration program in northern China (Liu et al, 2008), which is located in the mid-latitudes and controlled mainly by the westerly atmospheric systems. There are many factors for the relative importance between the two types of processes in a specific region.…”

Forest Influences on Climate and Water Resources at the Landscape to Regional Scale

“…A lower albedo value means more solar energy available (higher net radiation) for sensible heat and latent heat, i.e., evapotranspiration. A comparison of albedo and net radiation measured for a mid-rotation (15-year-old) and young loblolly pine .1 A conceptual model describing the interactions of forests, climate, and streamflow at multiple scales (modified from Liu et al 2008Liu et al , 2010 forest shows that albedo and net ration fluctuate seasonal and change over time due to the climate variation and plant development resulting a decrease in albedo and an increase in net radiation ( Fig. 15.2) (Sun et al 2010).…”