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L. Hua
Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, Soil and Water Conservation Research Centre, Huazhong Agricultural University, Wuhan 430070, China

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Journal article
Published: 10 August 2019 in Remote Sensing
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Drought, as an extreme climate event, affects the ecological environment for vegetation and agricultural production. Studies of the vegetative response to drought are paramount to providing scientific information for drought risk mitigation. In this paper, the spatial-temporal pattern of drought and the response lag of vegetation in Nebraska were analyzed from 2000 to 2015. Based on the long-term Daymet data set, the standard precipitation index (SPI) was computed to identify precipitation anomalies, and the Gaussian function was applied to obtain temperature anomalies. Vegetation anomaly was identified by dynamic time warping technique using a remote sensing Normalized Difference Vegetation Index (NDVI) time series. Finally, multilayer correlation analysis was applied to obtain the response lag of different vegetation types. The results show that Nebraska suffered severe drought events in 2002 and 2012. The response lag of vegetation to drought typically ranged from 30 to 45 days varying for different vegetation types and human activities (water use and management). Grasslands had the shortest response lag (~35 days), while forests had the longest lag period (~48 days). For specific crop types, the response lag of winter wheat varied among different regions of Nebraska (35–45 days), while soybeans, corn and alfalfa had similar response lag times of approximately 40 days.

ACS Style

Li Hua; Huidong Wang; Haigang Sui; Brian Wardlow; Michael J. Hayes; Jianxun Wang. Mapping the Spatial-Temporal Dynamics of Vegetation Response Lag to Drought in a Semi-Arid Region. Remote Sensing 2019, 11, 1873 .

AMA Style

Li Hua, Huidong Wang, Haigang Sui, Brian Wardlow, Michael J. Hayes, Jianxun Wang. Mapping the Spatial-Temporal Dynamics of Vegetation Response Lag to Drought in a Semi-Arid Region. Remote Sensing. 2019; 11 (16):1873.

Chicago/Turabian Style

Li Hua; Huidong Wang; Haigang Sui; Brian Wardlow; Michael J. Hayes; Jianxun Wang. 2019. "Mapping the Spatial-Temporal Dynamics of Vegetation Response Lag to Drought in a Semi-Arid Region." Remote Sensing 11, no. 16: 1873.

Journal article
Published: 22 February 2019 in Sustainability
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Soil aggregate stability is an important aspect of soil function and health. Fertilization could potentially alter soil properties and thereby affect aggregate stability. To determine which fertilizer is useful for improving soil fertility and stabilizing soil aggregates and thereby reducing soil erodibility, we examined three types of fertilizer, and measured how soil organic carbon, carbohydrates, and related soil properties influenced aggregate stability in eroded Ultisols. Treatments included control (CK), mineral fertilizer nitrogen (N), phosphorus (P), potassium (K) (NPK), fertilizer NPK plus straw (NPKS), and farmyard manure (FYM). Aggregate stability was tested according to Le Bissonnais method, involving three disruptive tests: fast wetting (FW), slow wetting (SW), and mechanical breakdown (WS). Total organic carbon, particulate organic carbon, mineral-associated carbon, and cold-water-soluble carbohydrate, hot-water-soluble carbohydrate, and dilute acid hydrolysable carbohydrate were measured, as well as soil intrinsic properties (including pH, bulk density, iron and aluminum oxides). The 12-year fertilization had a larger effect on aggregate stability and related soil properties in a 0–15 cm soil layer, whereas no effect was evident at a soil depth of 15–40 cm. MWD (mean weight diameter) under the three tests decreased with increasing soil depth. Fertilization, especially farmyard manure evidently improved MWDFW and MWDWS at a depth of 0–15 cm. Slaking was the main mechanism of aggregate breakdown in Ultisols studied, followed by mechanical breakdown. Correlation analysis showed that MWDFW and MWDWS at a depth of 0–15 cm increased with the increase of particulate organic carbon, total organic carbon, hot-water-soluble carbohydrate and pH. Furthermore, their interaction with amorphous iron oxides enhanced aggregate stability against slaking or, with amorphous aluminum oxides, modified aggregate stability against mechanical breakdown. Consequently, particulate organic carbon was the dominant cementing agent for aggregation in Ultisols studied, and its combination with pH, amorphous aluminum oxides, amorphous iron oxides, and free aluminum oxides play a synergetic role in stabilizing soil aggregate. Accordingly, farmyard manure or fertilizer NPK plus straw improved soil fertility and the ability to resist slaking.

ACS Style

Zhonglu Guo; Lichao Zhang; Wei Yang; Li Hua; Chongfa Cai. Aggregate Stability under Long-Term Fertilization Practices: The Case of Eroded Ultisols of South-Central China. Sustainability 2019, 11, 1169 .

AMA Style

Zhonglu Guo, Lichao Zhang, Wei Yang, Li Hua, Chongfa Cai. Aggregate Stability under Long-Term Fertilization Practices: The Case of Eroded Ultisols of South-Central China. Sustainability. 2019; 11 (4):1169.

Chicago/Turabian Style

Zhonglu Guo; Lichao Zhang; Wei Yang; Li Hua; Chongfa Cai. 2019. "Aggregate Stability under Long-Term Fertilization Practices: The Case of Eroded Ultisols of South-Central China." Sustainability 11, no. 4: 1169.

Journal article
Published: 06 November 2018 in CATENA
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Water erosion is a time-varying processes controlled by both rainfall and overland flow. A better understanding of dynamic changes in the sediment load and size distribution with various erosive forces can help to develop and verify erosion models. Here, a total of 11 laboratory simulation experiments were conducted in a 1 m by 3 m flume with 3 storm rainfall intensities (60, 90, 120 mm h−1) and 2 inflow rates (5, 7.5 L min−1) on a silty clay red soil. Time-series measurements of the quantity and size distribution of eroded materials were made during 50 min rainfall/inflow time. The mean weight diameter of the effective sediment, sediment enrichment ratio, average stream power and rainfall power were measured and calculated. Fine sediment particles were associated with the short-lived initial stage, which was combined with sheet flow erosion and splash erosion, whereas coarse particles were associated with the rill development and rill stable stages, which were dominated by rill erosion and interrill erosion, respectively. The <0.05 mm aggregates were transported preferentially by the suspension/saltation mechanism, while 0.105–0.25 mm aggregates resisted transportation. Additionally, the sediment load rate showed a significant linear correlation with the stream power at the sheet flow (R2 = 0.84, p < 0.01) and rill development (R2 = 0.72, p < 0.01) stages as well as the rainfall power at the rill development (R2 = 0.76, p < 0.01) and rill stable stages (R2 = 0.78, p < 0.01). Sediment size increased with increasing stream power (p < 0.05) and rainfall power (p < 0.05) only at the rill development stage. The erosion processes play a major role in particle selection, and the erosion forms, aggregate breakdown and soil surface structure development should be considered for a more accurate prediction of size selectivity and the related sediment quality.

ACS Style

Hao-Xin Hao; Jun-Guang Wang; Zhong-Lu Guo; Li Hua. Water erosion processes and dynamic changes of sediment size distribution under the combined effects of rainfall and overland flow. CATENA 2018, 173, 494 -504.

AMA Style

Hao-Xin Hao, Jun-Guang Wang, Zhong-Lu Guo, Li Hua. Water erosion processes and dynamic changes of sediment size distribution under the combined effects of rainfall and overland flow. CATENA. 2018; 173 ():494-504.

Chicago/Turabian Style

Hao-Xin Hao; Jun-Guang Wang; Zhong-Lu Guo; Li Hua. 2018. "Water erosion processes and dynamic changes of sediment size distribution under the combined effects of rainfall and overland flow." CATENA 173, no. : 494-504.

Journal article
Published: 31 August 2018 in Sustainability
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Daye is a city in China known for its rich mineral resources, with a history of metal mining and smelting that dates back more than 3000 years. To analyze the spatial distribution patterns, ecological risk, and sources of heavy metals (Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn) in soils, 213 topsoil samples were collected in the main urban area of Daye in September 2016. The mean concentrations of Cd, Cu, Pb, and Zn were higher than the corresponding background values, with the mean concentration of Cd being almost seven times its background value. Spatially, the high concentrations of Cd, Mn, Pb, and Zn were mainly concentrated in the southeastern part of the region due to nonferrous metal mining and smelting. However, the high concentrations of Co and Cu were concentrated in the central part of the study area, resulted from copper mining and smelting. The data of the geoaccumulation index showed that the contamination levels ranged from no pollution (Co, Cr, Mn, and Ni) to heavy contamination (Cd, Cu, and Pb). Ecological risk assessment showed that Cd posed a high, serious, and even severe ecological risk in 53.78% of the area of Daye. According to the results of the principal component analysis, mineral exploitation and smelting involving a variety of minerals (ES_M), mining exploitation, and smelting of copper ore (ES_C), and natural sources are the three main sources of heavy metals in these soils. Furthermore, the absolute principal component scores showed that 69.21% and 23.17% of the heavy metal concentrations were ascribed to ES_M and ES_C, respectively.

ACS Style

Li Hua; Xue Yang; Yajun Liu; Xiuli Tan; Yong Yang. Spatial Distributions, Pollution Assessment, and Qualified Source Apportionment of Soil Heavy Metals in a Typical Mineral Mining City in China. Sustainability 2018, 10, 3115 .

AMA Style

Li Hua, Xue Yang, Yajun Liu, Xiuli Tan, Yong Yang. Spatial Distributions, Pollution Assessment, and Qualified Source Apportionment of Soil Heavy Metals in a Typical Mineral Mining City in China. Sustainability. 2018; 10 (9):3115.

Chicago/Turabian Style

Li Hua; Xue Yang; Yajun Liu; Xiuli Tan; Yong Yang. 2018. "Spatial Distributions, Pollution Assessment, and Qualified Source Apportionment of Soil Heavy Metals in a Typical Mineral Mining City in China." Sustainability 10, no. 9: 3115.

Journal article
Published: 20 July 2018 in Science of The Total Environment
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This paper aims to investigate the hydrological response of a large-scale (8973 km2) mountainous watershed to different rainstorm spatial patterns and reforestation. Based on 32 years of observations, measurements of 184 rainstorm events and 125 sediment-producing events with complete hydrographs were analyzed. The K-means clustering method was used to classify the spatial patterns of rainstorm events in accordance with their event-based spatial rainfall characteristics. The 184 rainstorm events were classified into four spatial patterns, among which the spatial features differ significantly: (I) Spatial Pattern I (SPI) includes rainstorms with a low amount of cumulative areal rainfall (27.4 mm), the highest spatial variability (0.986), and the highest frequency; (II) Spatial Pattern II (SPII) includes rainstorms of high spatial variability (0.759) and the largest amount of local maximum daily rainfall (106.8 mm); (III) Spatial Pattern III (SPIII) includes rainstorms with a medium amount of cumulative areal rainfall (58.7 mm) and low spatial variability (0.362); and (IV) Spatial Pattern IV (SPIV) includes rainstorms with the largest amount of cumulative areal rainfall (117.2 mm) and the lowest spatial variability (0.313). Vegetation cover in the upper Du watershed was significantly improved after the implementation of the Grain-for-Green project. The average area-specific sediment yields (SSY) for the four SPs were 15.4, 65.5, 55.8, and 286.2 t km−2 before reforestation and decreased to 6.0, 59.3, 43.7 and 89.9 t km−2, respectively, after reforestation. ANOVA (analysis of variance) indicated that reforestation resulted in a significant reduction in runoff coefficient under SPIII and SPIV and a significant reduction in SSY under SPI and SPIV. A hysteresis analysis suggested that the proportion of events with a clockwise loop increased from 64.9% before reforestation to 82.1% after reforestation and that complex loops became less common during 2000–2010 under SPIV, thereby implying a reduced sediment supply.

ACS Style

X. Huang; N.F. Fang; T.X. Zhu; L. Wang; Z.H. Shi; L. Hua. Hydrological response of a large-scale mountainous watershed to rainstorm spatial patterns and reforestation in subtropical China. Science of The Total Environment 2018, 645, 1083 -1093.

AMA Style

X. Huang, N.F. Fang, T.X. Zhu, L. Wang, Z.H. Shi, L. Hua. Hydrological response of a large-scale mountainous watershed to rainstorm spatial patterns and reforestation in subtropical China. Science of The Total Environment. 2018; 645 ():1083-1093.

Chicago/Turabian Style

X. Huang; N.F. Fang; T.X. Zhu; L. Wang; Z.H. Shi; L. Hua. 2018. "Hydrological response of a large-scale mountainous watershed to rainstorm spatial patterns and reforestation in subtropical China." Science of The Total Environment 645, no. : 1083-1093.