The intensity of recent droughts and the uncertainty of moisture variability in the context of increasing temperatures and decreasing precipitation have affected the Mongolian grassland. Mongolia typifies the steppe t...The intensity of recent droughts and the uncertainty of moisture variability in the context of increasing temperatures and decreasing precipitation have affected the Mongolian grassland. Mongolia typifies the steppe terrain and semiarid to arid continental climate that extends across much of Central Asia. In semi-arid areas like Mongolian steppe, vegetation type and distribution are directly relate to the amount of water that plants can extract from the soil. An index for assessment of moisture availability (ma: defined as the ratio of actual to reference evapotranspiration) was developed, namely NTDI [1] 08D0C9EA79F9BACE118C8200AA004BA90B02000000080000000E0000005F005200650066003400300031003800340037003500380031000000 . NTDI (Normalized Day-Night Surface Temperature Difference Index) is defined as the ratio of the difference between the maximum daytime surface temperature and the minimum nighttime surface temperature, to the difference between the maximum and minimum surface temperatures estimated from meteorological data by applying energy balance equations. A verification study conducted at Liudaogou River Basin of the Loess Plateau, China, indicated the capability of NTDI to estimate ma accurately, (R2=0.97,p<0.001) [1] 08D0C9EA79F9BACE118C8200AA004BA90B02000000080000000E0000005F005200650066003400300031003800340037003500380031000000 . In Bayan Unjuul, Mongolia, application of NTDI during the growing season showed a significant inverse exponential correlation with ma (R2=0.86,p<0.001). This result indicates that the NTDI is potent to be used as a surrogate of moisture availability in steppe terrain of Central Asia.展开更多
There is a need for science and community knowledge and resources to be combined in the mitigation and rehabilitation of land degradation, as a large portion of degraded land in South Africa is communal land. Rainfall...There is a need for science and community knowledge and resources to be combined in the mitigation and rehabilitation of land degradation, as a large portion of degraded land in South Africa is communal land. Rainfall simulation was used at Okhombe valley, KwaZulu-Natal, South Africa as a tool to collect scientific data regarding the erosion rates on cattle access paths and to demonstrate erosion driving forces to the community members. The community members were able to experience erosion taking place through rainfall simulation and observe the impact of slope and basal cover change on erosion rates. Cattle access paths and rehabilitated access paths showed similar runoff rates (Figure 1), however the sediment concentration varied between the severely degraded cattle access paths and the rehabilitated land. Through the rainfall demonstration a better understanding of the driving factors in the erosion process, an understanding of why particular mitigation techniques work and where such mitigation measures would be effective were identified. With the combination of scientific techniques and community knowledge and resources a step can be taken towards sustainable land degradation mitigation and rehabilitation in the communal areas of South Africa.展开更多
文摘The intensity of recent droughts and the uncertainty of moisture variability in the context of increasing temperatures and decreasing precipitation have affected the Mongolian grassland. Mongolia typifies the steppe terrain and semiarid to arid continental climate that extends across much of Central Asia. In semi-arid areas like Mongolian steppe, vegetation type and distribution are directly relate to the amount of water that plants can extract from the soil. An index for assessment of moisture availability (ma: defined as the ratio of actual to reference evapotranspiration) was developed, namely NTDI [1] 08D0C9EA79F9BACE118C8200AA004BA90B02000000080000000E0000005F005200650066003400300031003800340037003500380031000000 . NTDI (Normalized Day-Night Surface Temperature Difference Index) is defined as the ratio of the difference between the maximum daytime surface temperature and the minimum nighttime surface temperature, to the difference between the maximum and minimum surface temperatures estimated from meteorological data by applying energy balance equations. A verification study conducted at Liudaogou River Basin of the Loess Plateau, China, indicated the capability of NTDI to estimate ma accurately, (R2=0.97,p<0.001) [1] 08D0C9EA79F9BACE118C8200AA004BA90B02000000080000000E0000005F005200650066003400300031003800340037003500380031000000 . In Bayan Unjuul, Mongolia, application of NTDI during the growing season showed a significant inverse exponential correlation with ma (R2=0.86,p<0.001). This result indicates that the NTDI is potent to be used as a surrogate of moisture availability in steppe terrain of Central Asia.
文摘There is a need for science and community knowledge and resources to be combined in the mitigation and rehabilitation of land degradation, as a large portion of degraded land in South Africa is communal land. Rainfall simulation was used at Okhombe valley, KwaZulu-Natal, South Africa as a tool to collect scientific data regarding the erosion rates on cattle access paths and to demonstrate erosion driving forces to the community members. The community members were able to experience erosion taking place through rainfall simulation and observe the impact of slope and basal cover change on erosion rates. Cattle access paths and rehabilitated access paths showed similar runoff rates (Figure 1), however the sediment concentration varied between the severely degraded cattle access paths and the rehabilitated land. Through the rainfall demonstration a better understanding of the driving factors in the erosion process, an understanding of why particular mitigation techniques work and where such mitigation measures would be effective were identified. With the combination of scientific techniques and community knowledge and resources a step can be taken towards sustainable land degradation mitigation and rehabilitation in the communal areas of South Africa.
