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Zheng X.,CAS Shenyang Institute of Applied Ecology | Zheng X.,University of Chinese Academy of Sciences | Zheng X.,Key Laboratory for Management of No commercial Forests | Zhu J.J.,CAS Shenyang Institute of Applied Ecology | And 5 more authors.
Agricultural Water Management | Year: 2012

Since the Three-North Shelter Forest Program was launched in 1978, more than 3.0×10 5ha of Mongolian pine (Pinus sylvestris var. mongolica, MP) plantations have been introduced to control erosion in sandy areas. However, MP plantations in the earliest introduction area (Zhanggutai region in Horqin Sandy Land, which dates back to 1954) declined at the beginning of the 1990s. Meanwhile, a linear decrease in the groundwater table was found during the years 1953-2009. This gave rise to concerns regarding the influence of introduced MP plantations on the environment. To clarify the relationships between land use changes, the decrease in the groundwater table, and the decline of MP plantations, land use changes from 1953 to 2009 were explored using remote sensing data, and the levels of water consumption associated with different types of land use were estimated using a modified CROPWAT model. The results showed that during the period 1953-2009, the area of bare sandy land in the study region sharply decreased by 89.7%. Agricultural land and broadleaved forests were the two major consumers of water resources, accounting for more than 40.0 and 20.0% of the total water consumption, respectively. MP plantations, in contrast, accounted for only about 12.0% of the total water consumption. The establishment of MP plantations has played a significant role in controlling the expansion of sandy land. Compared with agricultural land and broadleaved forests, MP plantations contribute less to the decrease in the groundwater table. The decline of the MP plantations may be a result of the decrease in available groundwater, but the MP plantations contributed less than expected to this decrease. To ensure a sustainable water balance, the area of agricultural land and broadleaved forests should be maintained below the maximum that can be supported by the guaranteed water resource. © 2012 Elsevier B.V.


Zheng X.,Key Laboratory for Management of No commercial Forests | Zheng X.,Chinese Academy of Sciences | Zheng X.,CAS Shenyang Institute of Applied Ecology | Zhu J.,Key Laboratory for Management of No commercial Forests | And 2 more authors.
Agricultural Systems | Year: 2016

The Three-North Shelter Forest Program (TNSFP), which is the largest ecological afforestation program worldwide, was launched in 1978 and will last until 2050 in the Three-North regions (accounting for 42.4% of China's territory). As a dominant component in the TNSFP, shelterbelts or windbreaks play an important role in preventing from wind damage and erosion and providing appropriate microclimate conditions for crop growth, thus improving crop yields. However, how shelterbelts influence crop yields at the regional scale has not yet been determined because there are certain difficulties in identifying the effects of shelterbelts on crop yields due to other factors such as climatic factors, crop seeds, fertilizer and management measures. In this study, a new approach is used to estimate the effects of shelterbelts on crop yields while overcoming these difficulties. The specific processes used in this study are detailed as follows. First, the climatic potential productivity, which is a combination of solar radiation, temperature and precipitation, was estimated using the multi-sensor remote data. All farmland in the region was divided into high, middle and low climatic potential productivity zones. Second, the crop (i.e., maize) yield across the Northeast China was estimated using the harvest index method and MODIS data. Third, according to the effectively protected distance, the levels of protection provided by the shelterbelts to the farmland at the regional scale were calculated by combining the stand age and the growth status of the shelterbelts using a time series of Landsat images. Finally, the levels of protection and the corresponding maize yields in pixels were extracted and averaged to identify the effects of shelterbelts on crop yields. The results of this study indicated that shelterbelts could enhance crop yields at the regional scale. The contribution rates of shelterbelts to increasing maize yields were found to be 4.68%, 4.28% and 9.45% in the high, middle and low climatic potential productivity zones, respectively. In Northeast China, the average level of protection of farmland was 18.28%, which was obviously lower than the optimal level of protection (i.e., approximately 80%); thus, many shelterbelts must be planted in the future. The findings of this study provide a sound theoretical foundation for increasing crop yields by planning shelterbelts in farmland regions similar to those in Northeast China. © 2015.


Zheng X.,CAS Shenyang Institute of Applied Ecology | Zheng X.,Key Laboratory for Management of No commercial Forests | Zheng X.,Chinese Academy of Sciences | Zheng X.,University of Chinese Academy of Sciences | And 4 more authors.
Theoretical and Applied Climatology | Year: 2015

Reference evapotranspiration (ETo) maps play an important role in distributed hydrological modeling and are particularly useful for regional agricultural and water resource management. In the Three-North Shelter Forest Program, water requirements (i.e., ETo) of different land use types are important preconditions for afforestation program management. The Food and Agriculture Organization Penman–Monteith (FAO-PM) method is the most common method for estimating ETo, but it requires many different types of meteorological data, and few stations with adequate meteorological resources exist in the Three-North regions. In addition, the spatial distribution of ordinary meteorological stations is limited. This study employed two temperature-based ETo methods, Hargreaves and Thornthwaite. The monthly mean, maximum, and minimum air temperatures were estimated using moderate resolution imaging spectroradiometer (MODIS) data. The original coefficients of Hargreaves and mean temperatures of Thornthwaite were modified for regional calibration (with the FAO-PM method as the standard). In the comparison between the original/adjusted Hargreaves and the original/adjusted Thornthwaite methods, the adjusted Hargreaves method was appropriate for estimating ETo in the Three-North regions. The average mean bias error (MBE) was −0.21 mm, the relatively root mean square error (RRMSE) was 13.44 %, the correlation coefficient (R2) was 0.85, and the slope (b) was 1.00 for the monthly ETo. While the MBE was 2.32 mm, the RRMSE was 7.07 %, the R2 was 0.90, and the b was 1.00 for the annual ETo. Therefore, it is possible to estimate monthly and annual ETo values for other parts of the country or the world using adjusted Hargreaves with the estimated air temperature data instead of using the FAO-PM with observed data. © 2014, Springer-Verlag Wien.


Zheng X.,CAS Shenyang Institute of Applied Ecology | Zheng X.,Key Laboratory for Management of No commercial Forests | Zheng X.,Chinese Academy of Sciences | Zhu J.,CAS Shenyang Institute of Applied Ecology | And 2 more authors.
Theoretical and Applied Climatology | Year: 2015

Afforestation and reforestation activities achieve high attention at the policy agenda as measures for carbon sequestration in order to mitigate climate change. The Three-North Shelter Forest Program, the largest ecological afforestation program worldwide, was launched in 1978 and will last until 2050 in the Three-North regions (accounting for 42.4 % of China’s territory). Shelter forests of the Three-North Shelter Forest Program have exhibited severe decline after planting in 1978 due to lack of detailed climatic classification. Besides, a comprehensive assessment of climate adaptation for the current shelter forests was lacking. In this study, the aridity index determined by precipitation and reference evapotranspiration was employed to classify climatic zones for the afforestation program. The precipitation and reference evapotranspiration with 1-km resolution were estimated based on data from the tropical rainfall measuring mission and moderate resolution imaging spectroradiometer, respectively. Then, the detailed climatic classification for the afforestation program was obtained based on the relationship between the different vegetation types and the aridity index. The shelter forests in 2008 were derived from Landsat TM in the Three-North regions. In addition, climatic zones and shelter forests were corrected by comparing with natural vegetation map and field surveys. By overlaying the shelter forests on the climatic zones, we found that 16.30 % coniferous forests, 8.21 % broadleaved forests, 2.03 % mixed conifer-broadleaved forests, and 10.86 % shrubs were not in strict accordance with the climate conditions. These results open new perspectives for potential use of remote sensing techniques for afforestation management. © 2015 Springer-Verlag Wien

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