Effects of vegetation near-soil-surface factors on runoff and sediment reduction in typical grasslands on the Loess Plateau, China
LI Panpan1, WANG Bing1,2, YANG Yanfen1,2,*(), LIU Guobin1,2
1State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F University, Yangling 712100, China 2State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling 712100, China
Vegetation near-soil-surface factors can protect topsoil from erosion, however, their contributions to the reduction of soil erosion, especially under natural rainfall events, have not been systematically recognized. This study was performed to quantify the effects of near-soil-surface factors on runoff and sediment under natural rainfall events on grasslands dominated by Bothriochloa ischaemum (Linn.) Keng (BI grassland) and Artemisia gmelinii Thunb. (AG grassland) in two typical watersheds on the Loess Plateau, China in 2018. By successive removal of the plant canopy, litter, biological soil crusts (BSCs) and plant roots, we established five treatments including plant roots, plant roots+BSCs, plant roots+BSCs+litter, intact grassland and bare land in each grassland type. In total, twenty runoff plots (5 m×3 m) with similar slopes and aspects were constructed in the two types of grasslands. Results showed that plant canopy, litter and roots reduced runoff, while BSCs, which swelled in the presence of water, increased runoff. In contrast, all of these factors reduced sediment yield. In addition, the reductions in runoff and sediment yield increased with I30 (maximum 30-min rainfall intensity) for each vegetation near-soil-surface factor except for BSCs. Among these factors, plant canopy had the largest contribution to runoff reduction, accounting for 48.8% and 39.9% in the BI and AG grasslands, respectively. The contributions of these vegetation near-soil-surface factors to sediment yield reduction were similar (21.3%-29.9%) in the two types of grasslands except for BSCs in the AG grassland (10.3%). The total reduction in runoff in the BI grassland (70.8%) was greater than that in the AG grassland (53.1%), while the reduction in sediment yield was almost the same in both grasslands (97.4% and 96.7%). In conclusion, according to the effects of different vegetation near-soil-surface factors on runoff and sediment production, our results may provide more complete insight and scientific basis into the effects of various vegetation related factors in controlling soil erosion.
LI Panpan, WANG Bing, YANG Yanfen, LIU Guobin. Effects of vegetation near-soil-surface factors on runoff and sediment reduction in typical grasslands on the Loess Plateau, China. Journal of Arid Land, 2022, 14(3): 325-340.
Fig. 1(a), distribution of two experimental plots; (b), BI grassland is the grassland with B. ischaemum as the dominant species; (c), AG grassland is the grassland with A. gmelinii as the dominant species. A schematic diagram of T1-T4 treatments is shown in Figure S1. The treatments named T0, T1, T2, T3, T4 and T5 indicate bare land, plant roots, plant roots+BSCs, plant roots+BSCs+litter, intact grassland and dead roots, respectively, and the T5 is not analyzed in the study. BSCs, biological soil crusts.
Fig. 2Reduction of runoff amount and sediment yield of different near-soil-surface factors at each rainfall event in the BI grassland (a, c) and AG grassland (b, d). F1, F2, F3 and F4 refer to plant canopy, litter, BSCs and plant roots, respectively.
Near-soil-surface factor
Runoff
Sediment yield
BI grassland
AG grassland
BI grassland
AG grassland
Plant canopy (%)
48.8a
39.9a
21.3a
29.5a
Plant litter (%)
13.5b
23.9a
24.3a
29.9a
BSCs (%)
-6.4c
-16.1c
24.2a
10.3b
Plant roots (%)
14.8b
5.3b
27.7a
27.0a
Table 1 Average contribution of each near-soil-surface factor to runoff and sediment yield reduction
Fig. 3Correlation analysis of rainfall characteristics with runoff and sediment yield under different near-soil-surface factors. P, precipitation; t, rainfall duration; IA, average rainfall intensity; I30, maximum 30-min rainfall intensity; E, rainfall kinetic energy; R, rainfall erosivity. RR_C and SR_C indicate runoff and sediment yield reduction caused by plant coverage; RR_L and SR_L indicate runoff and sediment yield reduction caused by litter; RR_B and SR_B indicate runoff and sediment yield reduction caused by BSCs (biological soil crusts); and RR_R and SR_R indicate runoff and sediment yield reduction caused by plant roots. **, P<0.01 level;*, P<0.05 level.
Fig. 4Variations in runoff and sediment yield reduction with I30 (maximum 30-min rainfall intensity) under different near-soil-surface factors in the BI grassland and the AG grassland. (a, e), plant canopy; (b, f), litter; (c, g), BSCs (biological soil crusts); (d, h), plant roots.
Fig. 5Contributions of grassland to runoff reduction (a) and sediment yield reduction (b)
Sample plot site
Soil layer (cm)
Soil organic carbon (g/kg)
Total nitrogen (g/kg)
NO3--N (mg/kg)
NH4+-N (mg/kg)
Bulk density (g/cm3)
BI grassland
0-10
6.33
0.39
3.16
3.98
1.22
10-20
3.09
0.21
0.79
2.71
1.41
20-30
2.68
0.18
0.77
4.79
1.46
30-40
2.50
0.16
0.58
2.59
1.44
AG grassland
0-10
7.67
0.41
0.55
3.64
1.16
10-20
4.19
0.29
0.82
2.67
1.19
20-30
3.17
0.18
0.66
3.18
1.33
30-40
2.76
0.17
0.63
3.44
1.31
Sample plot site
Soil layer (cm)
Soil water-stable aggregate (%)
>5.00 mm
2.00-5.00 mm
1.00-2.00 mm
0.50-1.00 mm
0.25-0.50 mm
<0.25 mm
BI grassland
0-20
33.96
8.47
6.83
6.60
5.05
39.09
AG grassland
0-20
21.35
6.94
4.19
4.00
2.94
60.58
Table S1 Basic soil information of sample plots
Sample site
Rainfall date
Rainfall (mm)
Rainfall duration (min)
I30 (mm/h)
Rainfall kinetic energy (MJ/hm2)
Rainfall erosivity (MJ•mm/(hm2•h))
BI grassland
31 Jul
5.6
684
7.3
1.0
7.3
9 Aug
3.6
263
4.8
0.5
2.5
11 Aug
3.0
113
5.6
0.6
3.2
18 Aug
9.8
147
12.0
2.0
23.9
22 Aug
41.0
1383
11.6
6.3
73.1
31 Aug
15.8
890
5.8
2.2
12.7
2 Sep
16.0
351
10.6
2.7
28.5
14 Sep
15.8
542
11.6
2.5
28.6
19 Sep
13.2
3181
2.5
1.4
3.4
AG grassland
9 Aug
4.4
227
6.8
0.9
6.3
11 Aug
7.8
122
6.8
1.7
11.2
22 Aug
15.6
363
9.6
2.9
27.5
31 Aug
26.4
779
11.6
5.1
59.5
2 Sep
20.4
283
11.6
4.1
47.5
14 Sep
9.6
498
5.0
1.7
8.2
Table S2 Characteristics of rainfall events
Treatment
Date
Runoff (mm)
Sediment (g/m2)
Date
Runoff (mm)
Sediment (g/m2)
Date
Runoff (mm)
Sediment (g/m2)
T0
31 Jul
0.1
6.1
18 Aug
5.3
1138.8
2 Sep
1.4
38.8
T1
0.1
1.8
3.2
416.0
1.0
13.4
T2
0.1
0.6
2.8
89.8
0.7
2.9
T3
0.1
0.6
1.3
15.4
0.3
0.5
T4
0.0
0.1
0.3
3.9
0.1
0.2
T0
9 Aug
0.0
0.4
22 Aug
5.1
359.4
14 Sep
2.7
102.8
T1
0.0
0.2
3.3
118.3
1.4
25.8
T2
0.0
0.1
3.3
22.2
1.3
8.8
T3
0.0
0.0
1.3
3.2
0.6
1.2
T4
0.0
0.0
0.3
0.6
0.1
0.3
T0
11 Aug
0.0
1.1
31 Aug
0.3
9.1
19 Sep
0.0
0.1
T1
0.0
0.3
0.2
2.4
0.0
0.0
T2
0.0
0.2
0.2
0.6
0.0
0.0
T3
0.0
0.1
0.1
0.2
0.0
0.0
T4
0.0
0.0
0.1
0.2
0.0
0.0
Table S3 Variations in runoff and sediment yield in the BI grassland under rainfall events
Treatment
Date
Runoff (mm)
Sediment (g/m2)
Date
Runoff (mm)
Sediment (g/m2)
T0
9 Aug
0.0
0.6
31 Aug
7.0
476.8
T1
0.0
0.1
5.5
202.3
T2
0.0
0.1
5.7
104.8
T3
0.0
0.0
3.3
30.1
T4
0.0
0.0
2.1
15.8
T0
11 Aug
0.0
0.5
2 Sep
2.3
46.0
T1
0.0
0.3
2.9
21.8
T2
0.0
0.3
2.7
19.2
T3
0.0
0.1
1.6
4.6
T4
0.0
0.0
0.5
1.0
T0
22 Aug
0.6
23.9
14 Sep
0.0
0.1
T1
0.4
9.9
0.0
0.1
T2
0.7
4.9
0.0
0.1
T3
0.3
0.3
0.0
0.1
T4
0.1
0.2
0.0
0.0
Table S4 Variations in runoff and sediment yield in the AG grassland under rainfall events
Fig. S1Schematic diagram of vegetation near-soil-surface factors involved in different treatments (T1-T4). BSCs, biological soil crusts.
Fig. S2Recorded rainfall events in the BI and AG grasslands during rainy season. BI grassland is the grassland with B. ischaemum as the dominant species, and AG grassland is the grassland with A. gmelinii as the dominant species. Non-effective rainfall events indicate that no runoff or sediment is generated. Effective rainfall events indicate that runoff and sediment are generated.
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