| 1. |
- Miao, Yubo, et al.
(författare)
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Greening of China and possible vegetation effects on soil moisture
- 2024
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Ingår i: Ecological Indicators. - 1470-160X. ; 158
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Tidskriftsartikel (refereegranskat)abstract
- Wetting and drying climate sequences and anthropogenic vegetation changes can have profound effects on the hydrological cycle and sustainability of terrestrial ecosystems. China contains many different climates, from humid to extremely arid and it contributes to the global mitigation strategies of climate change. China is also an important contributor to global greening and carbon sequestration. In view of this, we estimated the spatial and temporal variation of leaf area index (LAI), dryness/wetness index (DWI), and soil moisture (SM) in arid (A), semi-arid (SA), semi-humid (SH), and humid (H) climate zones during 1981–2018 in China and analyzed the patterns of DWI and LAI effects on SM under different vegetation greenness. The results showed a significantly increasing trend of LAI in all climatic zones, and the contribution was from highest to lowest: SH (8.17 × 10-3 m2 m−2 year−1), SA (7 × 10-3 m2 m−2 year−1), H (4.71 × 10-3 m2 m−2 year−1), and A (3.98 × 10-3 m2 m−2 year−1). The SA and A zones are becoming wetter, while the soil of SH and H zones are drying. The dry/wet climate variation plays a decisive role in soil moisture, while the role of vegetation is limited. Additionally, the LAI3 (mean LAI from 2016 to 2018) thresholds were 0.25–0.41 and 0.84–0.86 for A and SA as a whole, respectively, as well as 0.47–0.54 and 0.93–1.18 for grassland, respectively. When vegetation exceeded this threshold, the effect of vegetation on soil moisture showed a shift from increasing to decreasing change. Overall, the results of the study provide improved understanding of the atmosphere-soil-vegetation interactions under climate change, as well as effects of vegetation restoration and water conservation efforts.
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| 2. |
- Yang, Tao, et al.
(författare)
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Wind and rainfall erosion energy in large sediment generating and coarse sediment class areas of the middle Yellow river
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Ingår i: International Soil and Water Conservation Research. - 2095-6339.
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Tidskriftsartikel (refereegranskat)abstract
- Joint action by strong winds and high-intensive rainfall leads to serious soil erosion problems in large sediment generating and coarse sediment class areas of the middle Yellow River. Investigating the variation of trend and alternating wind and rainfall energy is an important prerequisite for controlling regional sediment transport problems. We calculated the wind and rainfall erosion energies by using the aerodynamic energy and rainfall kinetic energy formulas. The Mann-Kendall (MK) trend test and Theil-Sen approach were used to analyze the spatial-temporal variation and alternation of joint erosion energy during the last 40 years (1979–2018). The results show the following. 1) Wind erosion energy increased and rainfall erosion energy decreased. However, the former is larger than the latter. 2) The dominant erosive energy varies for different seasons. Wind erosive energy dominates in spring, and rainfall erosive energy dominates in summer. 3) There is a regular wind-rainfall-wind alternation of erosive energy. The wind-rainfall energies were alternately distributed in May–July and the rainfall-wind energies were alternately distributed in September–December. Furthermore, the dominant time of rainfall erosive energy decreased when wind erosive energy increased. The results can help decision makers to develop soil erosion control strategies to reduce soil erosion when it occurs in wind and water staggered areas.
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| 3. |
- Wang, Di, et al.
(författare)
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Forest restoration effects on soil preferential flow in the paleo-periglacial eastern liaoning mountainous regions, China
- 2024
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Ingår i: Journal of Cleaner Production. - 0959-6526. ; 467
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Tidskriftsartikel (refereegranskat)abstract
- To provide a practical reference index for the protection of water conservation forests and the establishment of vegetation in different forest restoration areas, we seek to clarify the preferential flow development and its influencing factors under different rainfall events in the forest restoration areas of paleo-periglacial landform in eastern Liaoning Province of China. To quantify the preferential flow development (PFI) in soil profile-scale through soil profile indexes, we carried out dual-tracer experiments with dyeing in two types of forest restoration lands (plantation forest, PF, and natural secondary forest, NSF) in the paleo-periglacial landform forestland to obtain the soil water infiltration trajectories and water-solute transport characteristics. The indexes of preferential flow morphology and pathway diversity (solute migration) were integrated to construct a more complete evaluation system of the PFI. In addition, we explored factors affecting the PFI through soil physical properties and root characteristics. The results showed that: (1) There were obvious preferential flows in both PF and NSF. Compared with NSF, preferential flow in PF diverged earlier, had greater non-equilibrium degree, more paths and higher development degree, and preferential flow was the main infiltration form. (2) Changes in infiltration amount played a key role in altering the PFI, i.e., increasing infiltration amount reduced the PFI, especially in PF (p < 0.05); (3) After water infiltration, the solute Br− diffusion range of the soil profile was wider than that of Brilliant Blue tracer, thus the development of preferential flow was better synthetical reflected by the indexes of water flow morphology and solute distribution characteristics; (4) Differences in the PFI can be explained by variations in clay content, total porosity (TP), and root volume density (RVD), with total path coefficients of 0.824, 0.462, and 0.624, respectively. In addition to establishing different forest restoration types in similar areas, it would be worthwhile to strengthen the prevention and control measures of soil and water loss in NSF, and properly manage PF in a near-natural model to enhance ecologically sustainable development of forest land. The results of this study contribute to the understanding of the hydrological processes of forest ecosystems in paleo-periglacial landforms, and provide theoretical support for the proposed forest management strategies.
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| 4. |
- Wang, Di, et al.
(författare)
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Predicting Soil Saturated Water Conductivity Using Pedo-Transfer Functions for Rocky Mountain Forests in Northern China
- 2023
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Ingår i: Forests. - 1999-4907. ; 14:6
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Tidskriftsartikel (refereegranskat)abstract
- Soil physicochemical properties and macropore spatial structure affect saturated hydraulic conductivity (Ks). However, due to regional differences and long measurement time, Ks is tedious to quantify. Therefore, it is of great importance to find simplified but robust methods to predict Ks. One possibility is to use pedo-transfer functions (PTFs). Along this line, stratified sampling was carried out in six typical forestlands in the rocky mountain area of Northern China. Penetration experiments and industrial CT scanning were combined to explore the distribution characteristics of regional Ks and its influencing factors. Based on this, we compared three Ks PTF models by multiple linear regression for Ks prediction. The results indicated that: (1) Ks decreased with increasing soil depth, which followed the order coniferous forest < broad-leaved forest < mixed forest, and the change range of mixed forest was greater than that of homogeneous forest. (2) Soil bulk density, water content, sand, silt, organic matter, total nitrogen, total phosphorus, and total potassium were significantly correlated with Ks (p < 0.05). In addition, stand type and soil depth had a certain impact on soil physicochemical properties that affected Ks. (3) Soil macropore structure, such as number density, length density, surface area density, and volume density, all decreased with increasing soil depth. They were all significantly positively correlated with Ks (p < 0.001). (4) The best predictability and universality for PTFs was achieved for PTFs containing bulk density, organic matter content, and total phosphorus. Only PTFs containing parameters of macropore spatial structure did not yield high predictability of Ks. The findings of this study contribute to the understanding of forest hydrological infiltration processes in rocky mountain forests in Northern China, and provide theoretical support for the prediction and management of water loss and soil erosion and the enhancement of water conservation functions.
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| 5. |
- Wang, Di, et al.
(författare)
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Soil water infiltration characteristics of reforested areas in the paleo-periglacial eastern Liaoning mountainous regions, China
- 2024
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Ingår i: Catena. - 0341-8162. ; 234
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Tidskriftsartikel (refereegranskat)abstract
- Plantation forests (PF) and natural secondary forests (NSF) are the primary reforestation approaches. The establishment of PF can affect forest hydrological processes by changing soil structure. To date, few studies have focused on these changes and the effects on hydrological processes for the paleo-periglacial landform. To reveal reforestation approaches effects on water infiltration, including soil water infiltration capacity, retention capacity, and waterflow path pattern, we conducted field dye-tracer investigations with rainfall and laboratory infiltration experiments for the paleo-periglacial landform of eastern Liaoning mountains, China. The results showed that (1) Soil physical properties (including total porosity (TP), capillary porosity (CP), non-capillary porosity (NCP), initial soil water content (IWC), field water capacity (FWC)) and root abundance (RA) decreased with soil depth in both PF and NSF, while the soil bulk density (BD) and distribution of gravel content showed opposite changes. (2) Establishment of PF reduced the infiltration capacity and water retention capacity in the 0–20 cm layer, but enhanced the water retention capacity in 20–30 cm layer. Low IWC was conducive to increase soil water content (SWC) after infiltration. (3) Infiltration capacity parameters (including saturated hydraulic conductivity (Ks), SWC, difference between SWC and IWC (SWC–IWC), dye coverage ratio (DC)) were significantly correlated with BD, TP, CP, NCP, FWC, and fine roots RA (P < 0.05). Better connectivity gravels were more conducive to water infiltration. (4) Preferential flow was the main infiltration type, but with different waterflow paths pattern, with the 'funnel', 'finger' shape for PF, NSF, respectively. Increasing infiltration could increase flow path connectivity. Our findings show that soil physical properties, roots, and gravel occurrence affected soil infiltration, and different reforestation approaches had varying impacts on soil infiltration, water redistribution, transportation, and storage of surface and groundwater, improving the understanding of ecohydrological processes and effects of water resources management in forest ecosystems of paleo-periglacial landform.
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