水保所知识产出(1956---)知识库

Net soil CO 2 emissions are not independent of topography but tend to decline with
increasing slope gradients. Such decline has been attributed to increased runoff and
greater soil loss on steep slopes, leaving the soil less habitable for microorganisms.
However, the specific variations of slope gradients and thus the associated soil properties
relevant for CO 2 emissions, especially from terraced slopes, are often disguised by the
coarse resolution of digital terrain models (DTMs) based on commonly available open-
source data. Such misrepresentation of the relationship between topography and soil CO 2
emissions carries the risk of a wrong assessment of soil-atmosphere interaction. By
applying a slope dependent soil CO 2 emission model developed from erosion plots to
nearby sloping and partially terraced cropland using two DTMs of different spatial
resolutions, this study tested the significance of these resolution-induced errors on
CO 2 emission estimates. The results show that the coarser-resolution Shuttle Radar
Topography Mission (SRTM) underestimated CO 2 -C emission by 27% compared to the
higher-resolution DTM derived from Unmanned Aerial Vehicles (UAV) imagery. Such
difference can be mostly attributed to a better representation of the proportion of flat
slopes in the high-resolution DTM. Although theobservationsfrom erosion plots cannot be
directly extrapolated to a larger scale, the 27% underestimation using the coarser-
resolution SRTM DTM emphasizes that it is essential to represent microreliefs and their
impact on runoff and erosion-induced soil heterogeneity at an appropriate scale. The
widespread impact of topography on erosion and deposition on cropland, and the
associated slope-dependent heterogeneity of soil properties, may lead to even greater
differences than those observed in this study. The greatly improved estimation on CO 2
emissions by the UAV-derived DTM also demonstrates that UAVs have a great potential to
fill the gap between conventional field investigations and commonly applied coarse-
resolution remote sensing when assessing the impact of soil erosion on global soil-
atmosphere interaction.