Hydrogeomorphic Ecosystem Responses to Natural and Anthropogenic Changes in the Loess Plateau of China

Fu, Bojie; Wang, Shuai; Li, Yu; Li, Jianbo; Liang, Wenju; Miao, Chiyuan

doi:10.1146/annurev-earth-063016-020552

Cited by 699 publications

(454 citation statements)

References 70 publications

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“…The channels of the Loess Plateau are incising into wind-blown sediments that drape an extensive area of over 400 000 km 2 (Zhang, 1980) and can exceed 300 m thickness (Fu et al, 2017). The plateau is underlain by the Ordos Block, a succession of non-marine Mesozoic sediments which has undergone stable uplift since the Miocene (Yueqiao et al, 2003;.…”

Section: An Example Of a Relatively Uniform Landscapementioning

confidence: 99%

How concave are river channels?

et al. 2018

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Abstract. For over a century, geomorphologists have attempted to unravel information about landscape evolution, and processes that drive it, using river profiles. Many studies have combined new topographic datasets with theoretical models of channel incision to infer erosion rates, identify rock types with different resistance to erosion, and detect potential regions of tectonic activity. The most common metric used to analyse river profile geometry is channel steepness, or k s . However, the calculation of channel steepness requires the normalisation of channel gradient by drainage area. This normalisation requires a power law exponent that is referred to as the channel concavity index. Despite the concavity index being crucial in determining channel steepness, it is challenging to constrain. In this contribution, we compare both slope-area methods for calculating the concavity index and methods based on integrating drainage area along the length of the channel, using so-called "chi" (χ) analysis. We present a new χ-based method which directly compares χ values of tributary nodes to those on the main stem; this method allows us to constrain the concavity index in transient landscapes without assuming a linear relationship between χ and elevation. Patterns of the concavity index have been linked to the ratio of the area and slope exponents of the stream power incision model (m/n); we therefore construct simple numerical models obeying detachment-limited stream power and test the different methods against simulations with imposed m and n. We find that χ-based methods are better than slope-area methods at reproducing imposed m/n ratios when our numerical landscapes are subject to either transient uplift or spatially varying uplift and fluvial erodibility. We also test our methods on several real landscapes, including sites with both lithological and structural heterogeneity, to provide examples of the methods' performance and limitations. These methods are made available in a new software package so that other workers can explore how the concavity index varies across diverse landscapes, with the aim to improve our understanding of the physics behind bedrock channel incision.

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Section: An Example Of a Relatively Uniform Landscapementioning

confidence: 99%

How concave are river channels?

et al. 2018

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“…Land degradation has been considered a vital economic, social, and ecological problem owing to its impact on food security and ecological environment (Lu, Batistella, Mausel, & Moran, ), which has stroked the attention of the world, especially on the Loess Plateau of China. The Loess Plateau, characterized by the deepest loess deposits in the world, not only has a unique landscape but is also known for its fragile ecosystem, which is especially vulnerable to soil erosion (Fu et al, ). Although some measures, such as the construction of check dams (Zhao, Mu, Wen, Wang, & Gao, ) and terraces (Wei et al, ), have resulted in prominent reductions in soil erosion, vegetation restoration has also had an important influence on soil and water conservation (Lu et al, ).…”

Section: Introductionmentioning

confidence: 99%

Decline in soil moisture due to vegetation restoration on the Loess Plateau of China

Shangguan

2018

Land Degrad Dev

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Afforestation brings lots of water‐related benefits, including reducing soil erosion and improving water conservation, simultaneously; it is considered to be a land use activity, which threatens water resources security. Characterizing the response of soil moisture to revegetation is important for the sustainability of water and plants on the Loess Plateau of China. In this study, we conducted a meta‐analysis of 1,262 observations from 66 published studies to evaluate the effect of land use on the soil moisture of forest, shrubland, and grassland regions at a depth of 5 m in different ecological zones of the Loess Plateau. The results indicated that (a) Soil moisture content (SMC) decreased after land use conversion in all three ecological zones and was inconsistent among different soil layers. (b) Except for other grassland species, changes in the response size for soil moisture were not significant among any tree species, including Pinus tabuliformis, Robinia pseudoacacia, other forest species, Caragana korshinskii, other shrubland species, and Medicago sativa. (c) Soil moisture changes varied with different restoration types and ages. (d) The change in response to precipitation was not significant, whereas the change in response to temperature was significant. In addition, the responses of the initial soil moisture levels exhibited a negative correlation with revegetation. These results indicate that it is vital for scientific afforestation in the Loess Plateau to complement local climate conditions and soil properties.

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“…However, Xin, Yu, and Lu () found that annual high‐intensity or erosive rainfall fluctuated more than total annual rainfall. In addition, these fluctuations may affect soil erosion (Fu et al, ). The values of the rainfall erosivity factor for the 1980s, 1990s, 2000s, and 2010s are 594, 610, 643, and 606 MJ mm·ha −1 ·h −1 ·yr −1 , respectively (Figure d).…”

Section: Discussionmentioning

confidence: 99%

“…However, planted vegetation in such arid and semiarid areas has high water demand; the vegetation intercepts rainfall and likely causes reductions in soil moisture (Mongil‐Manso et al, ). Thus, maintaining a sustainable vegetated ecosystem to achieve the objective of solving the problem of severe soil erosion and maintaining ecosystem security on the Loess Plateau are important challenges (Fu et al, ; S. Wang et al, ).…”

Section: Discussionmentioning

confidence: 99%

The synergistic effects of afforestation and the construction of check‐dams on sediment trapping: Four decades of evolution on the Loess Plateau, China

Liu

Feng

et al. 2019

Land Degrad Dev

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Soil erosion represents a major environmental threat to ecosystems. Effective sediment trapping relies on the cooperation of multiple soil erosion control measures. However, findings on the synergistic effects of multiple soil erosion control measures are still lacking, in particular on a large spatial scale. This study provides a first attempt to analyze four decades of data from the 1980s to the 2010s on the Loess Plateau. The analysis combines the spatial investigation of check‐dam construction in gullies, afforestation on hillslopes, and station‐observed sediment yield within the evaluation framework of the Water and Tillage Erosion Model/Sediment Delivery Model. The results indicate two periods of effective sediment trapping on the Loess Plateau in the last four decades: 1980s–1990s and 2000s–2010s. Check‐dam construction was the main driver of reduced sediment yields before the 1990s. Massive afforestation played an increasingly important role beginning in 1999. The synergistic effects of afforestation and the construction of check‐dams in the period from the 2000s to the 2015 include not only the effective trapping of sediment but also the improvements in the resistance of ecosystems to climate change. These results improve our understanding of the synergistic effects of multiple soil erosion control measures on sediment trapping. The findings support a rational collocation of different soil erosion control measures to support comprehensive management in erosion‐prone regions.

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Hydrogeomorphic Ecosystem Responses to Natural and Anthropogenic Changes in the Loess Plateau of China

Cited by 699 publications

References 70 publications

How concave are river channels?

How concave are river channels?

Decline in soil moisture due to vegetation restoration on the Loess Plateau of China

The synergistic effects of afforestation and the construction of check‐dams on sediment trapping: Four decades of evolution on the Loess Plateau, China

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