**5. Conclusions**

Consistent with the spatial changes in precipitation, there were areas with significantly changed energy budget extending beyond the degraded area. Outside the Guizhou Karst Plateau, the variations in sensible heat flux and latent heat flux were controlled by the precipitation differences. For example, in the areas between 30°–34°N, 112°– 120°E (i.e., the southeastern coastal area of China), the increased evaporation (**Figure 13f**) was caused by the increase in precipitation (**Figure 12a**), which further led to the lower temperature (**Figure 12b**), and the lower sensible heat flux (**Figure 13e**). The issue on the impact of atmospheric

**Figure 13(g)** shows the impacts of cloud albedo and land surface albedo on shortwave radiation. In the degraded areas within Guizhou Karst Plateau, the cloud fraction was reduced due to the less evaporation and moisture flux convergence after land degradation, and the reduced cloud fraction further led to more incoming shortwave radiation. However, the increase in upward shortwave radiation (**Figure 13a**) due to the higher land surface albedo was much more than the downward shortwave radiation, which resulted in the reduced net shortwave radiation (**Figure 13b**). Moreover, in the southeastern coastal areas of China, the increased cloud fractions, consistent with more rainfall, led to the decrease in incoming

The modified water and energy budget due to Karst rocky desertification was the first-order effects. Because of the different input of heat and moisture into atmospheric circulation, the large-scale circulation features were altered, resulting in climatic effects beyond the desertification area. As shown in **Figure 14**, the weakened 3-month mean wind vector at 700 hPa

circulations on precipitation will be discussed in the next section.

shortwave radiation, dominating the alteration in net shortwave radiation.

**Figure 14.** Ensemble mean differences in JJA wind vector (m/s) at 700 hPa between Case D and Case C.

**4.7. Effects of KRD on atmospheric circulation**

48 Land Degradation and Desertification - a Global Crisis

The growing-season NDVI increased significantly during the last 30 years in the Karst region of the southwest China. There were also differences in the increase rate of vegetation types. The distribution of NDVI presented obvious spatial patterns, specifically, lower values in the western part and higher values in the east. The correlation between NDVI and climatic factors implied the limiting role of temperature for the vegetation growth and distribution in the study area, although the regression coefficients presented spatial heterogeneity. Additionally, the decreased NDVI was analyzed to detect the influencing mechanism. It was found that the increased cloud cover and rainfall led to the decrease in solar radiation and temperature, and further impeded photosynthesis.

We also observed that after the land cover change, there is need to consider its climatic effects through the impact of LCC on land surface water and energy budget. Karst rocky desertification (i.e., extensive exposure of basement rocks, serious soil erosion, drastic decrease in soil productivity and appearance of desert-like landscape) can modify the energy budget at land surface and then the regional climate. Specifically, after land degradation, the higher surface albedo and temperature caused the reduced net shortwave radiation and net longwave radiation. The sensible heat flux was increased by the higher temperature. Specifically, the substantial increase in sensible heat flux from ground offset the decrease in that from canopy. Due to higher stomatal resistance and lower LAI, the latent heat flux in KRD was reduced significantly. Less atmospheric heating from degraded land resulted in relative subsidence and less moisture flux convergence (MFC). The decrease in rainfall was probably attributed by both the reduced MFC and the reduced evaporation. A feedback loop was activated when precipitation was affected, for example, the altered soil moisture, vegetation growth, and phenology can further result in less diabatic heating rates, less moisture flux convergence, and lower rainfall. Moreover, the changed rainfall beyond the degraded areas was more significant. The modified energy and water balance due to land degradation weakened the southwest monsoon flow and affected the atmospheric circulation and moisture flux. In the southeastern coastal areas, the precipitation increased due to two reasons: (1) the weaker low-layer anticyclone causing the stronger vertical ascending motion, (2) the air mass diverging in the lower troposphere accompanying rising up over southeastern China.
