| Analysis on the natural factors affecting NPP in Loess Plateau |
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| DOI：10.7606/j.issn.1000-7601.2016.04.37 |
| Key Words: NPP substance CASA model the natural influence factors Loess Plateau |
| Author Name | Affiliation | | XU Qian | School of Geography and Planning/Center of Land Research, Sun Yat-Sen University, Guangzhou 510062, China | | Yang Ren | School of Geography and Planning/Center of Land Research, Sun Yat-Sen University, Guangzhou 510062, China | | REN Zhi-yuan | College of Tourism & Environment Science, Shaanxi Normal University, Xi’an, Shaanxi 710062, China |
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| Abstract: |
| This study explored differences of natural factors that affected NPP and the driving factors of NPP, which was based on a variety of data of natural geographical elements including the type of land-forms, and SPOT NDVI using a modified light use efficiency model. The study showed that from 1998 to 2010, the mean value of NPP substance changed from 9.884 gC·m-2·a-1 to 50.790 gC·m-2·a-1 in the Loess Plateau region. The value was lower than the national average level which was 342 gC·m-2·a-1. In addition, natural factors that affected the changes of NPP showed significant differences. The loess platform had high water retention, low water loss and soil erosion intensity, such that NPP substance became increased significantly. NPP was maintained at a relatively low level and was dropped significantly in wind erosion landform areas. Dry and wet conditions were important natural elements which affected the changes of NPP. NPP increase amount was much bigger in semi-humid zone than others. Slope had significantly effects on NPP changes. With the increase of vegetation coverage in steep slope areas, NPP was obviously increased. Within micro scales, heat water spatial distribution was found to be related with the elevation. In the study areas, NPP was significantly increased at altitude from 200 m to 1 000 m. However, NPP was shown to become declined when altitude was over 1 000 m. Furthermore, the dominant factor which affected the differences of NPP special distribution was hydro-thermal condition. But the main effect factor of NPP substance based on loess ridge and loess hill was altitude. Its correlation coefficient was 0.52, under the 0.01 confidence level. There was a significant negative correlation between solar radiation and NPP, which was particularly apparent in arid region. |
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