Journal of Resources and Ecology >
Rating the Degradation of Natural Hay Pastures in Northern China
Received date: 2018-10-19
Accepted date: 2018-12-30
Online published: 2019-03-30
Supported by
National Key Research and Development Program of China (2017YFC0503805, 2016YFC0500603, 2017YFE0104500)
China Agriculture Research System (CARS-34)
National Nonprofit Institute Research Grant of CAAS (821-32).
Copyright
Natural hay pastures in semi-arid pastoral areas produce the highest yields of hay in northern China. However, long-term continuous hay harvesting with no rest interval has resulted in severe degradation across widespread areas of these natural hay pastures. In addition, no clear data exist on the spatial distribution or degree of degradation occurring in natural hay pastures primarily because a nationally unified and normative evaluation standard is lacking. In view of the above problems, we employed an analytic hierarchy process to carry out screening and accuracy validation of evaluation indicators for natural hay pastures in north China grasslands (temperate meadow steppes, temperate steppes, mountain meadows, and lowland meadows). Our study identified seven easily measured indicators that reflect the state of natural hay pastures (average height, aboveground biomass, coverage, proportion of medium grasses, litter biomass, proportion of degradation-indicative plants, and proportion of bare spots and saline-alkali spots). A five-level scoring method was employed to delineate the threshold range for these indicators, The results of this study show that this method effectively solved the technical bottleneck for graded evaluation of degradation in natural hay pastures. This provides a theoretical basis for the scientific assessment of natural hay pasture degradation as well as important technical support for sustainable use of natural hay pastures and livestock production.
Key words: natural hay pastures; degradation; grading; grassland classification
XU Lijun , SHEN Beibei , NIE Yingying , XIN Xiaoping , GAO Wa , LI Da , WANG Di , YAN Ruirui , CHEN Baorui . Rating the Degradation of Natural Hay Pastures in Northern China[J]. Journal of Resources and Ecology, 2019 , 10(2) : 163 -173 . DOI: 10.5814/j.issn.1674-764X.2019.02.007
Fig. 1 Distribution of several types of natural hay pasture in the semi-arid region of north China |
Table 1 Selection of degradation rating indices of natural hay pasture in north China |
A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
A | 1 | 1 | 1 | 2 | 3 | 3 | 1 | 2 | 2 | 1 | 3 | 2 | 3 | 3 | 7 | 3 | 3 | 9 | 2 | 3 | 3 | 5 |
B | 1 | 1 | 1 | 2 | 3 | 3 | 1 | 2 | 2 | 2 | 4 | 3 | 3 | 3 | 8 | 5 | 5 | 9 | 2 | 5 | 4 | 6 |
C | 1 | 1 | 1 | 2 | 3 | 3 | 1 | 2 | 2 | 2 | 4 | 2 | 3 | 3 | 7 | 4 | 4 | 9 | 2 | 4 | 3 | 5 |
D | 1/2 | 1/2 | 1/2 | 1 | 2 | 2 | 1/2 | 1 | 1 | 1 | 2 | 1 | 2 | 2 | 4 | 2 | 2 | 6 | 1 | 2 | 2 | 3 |
E | 1/3 | 1/3 | 1/3 | 1/2 | 1 | 1 | 1/2 | 1 | 1 | 1/2 | 2 | 1 | 1 | 1 | 3 | 2 | 2 | 5 | 1 | 2 | 2 | 2 |
F | 1/3 | 1/3 | 1/3 | 1/2 | 1 | 1 | 1/2 | 1 | 1 | 1/2 | 2 | 1 | 1 | 1 | 3 | 2 | 2 | 5 | 1 | 2 | 1 | 2 |
G | 1 | 1 | 1 | 2 | 2 | 2 | 1 | 2 | 2 | 2 | 3 | 2 | 4 | 3 | 6 | 4 | 2 | 9 | 2 | 3 | 3 | 5 |
H | 1/2 | 1/2 | 1/2 | 1 | 1 | 1 | 1/2 | 1 | 1 | 1 | 2 | 1 | 2 | 2 | 4 | 2 | 2 | 6 | 1 | 2 | 2 | 3 |
I | 1/2 | 1/2 | 1/2 | 1 | 1 | 1 | 1/2 | 1 | 1 | 1 | 2 | 1 | 2 | 2 | 4 | 2 | 2 | 6 | 1 | 2 | 2 | 3 |
J | 1 | 1/2 | 1/2 | 1 | 2 | 2 | 1/2 | 1 | 1 | 1 | 2 | 2 | 2 | 5 | 3 | 3 | 8 | 1 | 3 | 2 | 3 | 3 |
K | 1/3 | 1/4 | 1/4 | 1/2 | 1/2 | 1/2 | 1/3 | 1/2 | 1/2 | 1/2 | 1 | 1/2 | 1 | 1 | 2 | 1 | 1 | 3 | 1/2 | 1 | 1 | 1 |
L | 1/2 | 1/3 | 1/2 | 1 | 1 | 1 | 1/2 | 1 | 1 | 1/2 | 2 | 1 | 1 | 1 | 3 | 2 | 2 | 5 | 1 | 1 | 1 | 2 |
M | 1/3 | 1/3 | 1/3 | 1/2 | 1 | 1 | 1/4 | 1/2 | 1/2 | 1/2 | 1 | 1 | 1 | 1 | 2 | 2 | 2 | 5 | 1 | 1 | 1 | 2 |
N | 1/3 | 1/3 | 1/3 | 1/2 | 1 | 1 | 1/3 | 1/2 | 1/2 | 1/5 | 1 | 1 | 1 | 1 | 2 | 2 | 2 | 4 | 1/2 | 1 | 1 | 2 |
O | 1/7 | 1/8 | 1/7 | 1/4 | 1/3 | 1/3 | 1/6 | 1/4 | 1/4 | 1/3 | 1/2 | 1/3 | 1/2 | 1/2 | 1 | 1/2 | 1/2 | 2 | 1/3 | 1/2 | 1/2 | 1 |
P | 1/3 | 1/5 | 1/4 | 1/2 | 1/2 | 1/2 | 1/4 | 1/2 | 1/2 | 1/3 | 1 | 1/2 | 1/2 | 1/2 | 2 | 1 | 1 | 3 | 1/2 | 1 | 1 | 1 |
Q | 1/9 | 1/9 | 1/9 | 1/6 | 1/5 | 1/5 | 1/9 | 1/6 | 1/6 | 1 | 1/3 | 1/5 | 1/5 | 1/4 | 1/2 | 1/3 | 1/3 | 1 | 1/6 | 1/3 | 1/3 | 1/2 |
R | 1/2 | 1/2 | 1/2 | 1 | 1 | 1 | 1/2 | 1 | 1 | 1/3 | 2 | 1 | 1 | 2 | 3 | 2 | 2 | 6 | 1 | 2 | 2 | 3 |
S | 1/3 | 1/5 | 1/4 | 1/2 | 1/2 | 1/2 | 1/3 | 1/2 | 1/2 | 1/2 | 1 | 1/2 | 1 | 1 | 2 | 1 | 1 | 3 | 1/2 | 1 | 1 | 1 |
T | 1/3 | 1/4 | 1/3 | 1/2 | 1/2 | 1 | 1/3 | 1/2 | 1/2 | 1/3 | 1 | 1/2 | 1 | 1 | 2 | 1 | 1 | 3 | 1/2 | 1 | 1 | 1 |
U | 1/5 | 1/6 | 1/5 | 1/3 | 1/2 | 1/2 | 1/5 | 1/3 | 1/3 | 1/3 | 1 | 1/2 | 1/2 | 1/2 | 1 | 1 | 1 | 2 | 1/3 | 1 | 1 | 1 |
Note: A: Average height; B: Aboveground biomass; C: Coverage; D: Proportion of medium grasses; E: Proportion of reduction in plant species; F: Litter biomass; G: Proportion of degradation-indicative plants; H: Proportion of bare spots and saline-alkali spots; I: Proportion of edible herbivorous species in all species; J: Proportion of increase in edible herbivorous species; K: Proportion of non-edible grass in total herbaceous vegetation; L: Proportion of harmful grasses in total herbaceous vegetation; M: Proportion of increase in soil erosion modulus; N: Proportion of rodent hole area in grassland area; O: Proportion of increase in soil bulk density in the soil layer; P: Proportion of reduction in total nitrogen content in the soil layer; Q: Proportion of increase in soil salinity; R: Proportion of reduction in organic matter content; S: Proportion of grasses; T: Proportion of increase in desertification-indicative plants; U: Proportion of increase in salinization-indicative plants;V: ??? |
Table 2 Weights of the degradation indices of natural hay pasture in north China |
Indicator | Weight | Indicator | Weight |
---|---|---|---|
Aboveground biomass | 0.104 | Litter biomass | 0.039 |
Coverage | 0.096 | The proportion of harmful grasses in total herbaceous vegetation | 0.033 |
Proportion of degradation-indicative plants | 0.090 | Proportion of increase in soil erosion modulus | 0.031 |
Average height | 0.089 | Proportion of increase in desertification-indicative plants | 0.026 |
Litter biomass | 0.070 | Proportion of increase in edible herbivorous species | 0.025 |
Proportion of medium grasses | 0.053 | Proportion of grasses | 0.025 |
Proportion of bare spots and saline-alkali spots | 0.050 | Proportion of reduction in total nitrogen content in the soil layer | 0.023 |
Proportion of edible herbivorous species in all species | 0.050 | Proportion of increase in soil bulk density in the soil layer | 0.023 |
Proportion of reduction in organic matter content | 0.046 | Proportion of increase in salinization-indicative plants | 0.019 |
Proportion of non-edible grass in total herbaceous vegetation | 0.041 | Proportion of rodent hole area in grassland area | 0.014 |
Proportion of reduction in plant species | 0.041 |
Table 3 Critical values of the degradation index for natural hay pasture in north China |
Indicator | Max | Min | |
---|---|---|---|
Average height (cm) | Temperate meadow steppe | 55 | 32 |
Temperate steppe | 46 | 25 | |
Mountain meadow | 50 | 30 | |
Lowland meadow | 80 | 49 | |
Aboveground biomass (kg ha-1) | Temperate meadow steppe | 1800 | 720 |
Temperate steppe | 1200 | 480 | |
Mountain meadow | 1600 | 600 | |
Lowland meadow | 2500 | 1000 | |
Coverage (%) | Temperate meadow steppe | 85 | 40 |
Temperate steppe | 60 | 26 | |
Mountain meadow | 90 | 51 | |
Lowland meadow | 98 | 61 | |
Proportion of medium grasses (%) | 50 | 10 | |
Litter biomass (kg ha-1) | 400 | 100 | |
Undegraded | Lower limit of degradation | ||
Proportion of degradation-indicative plant (%) | 0-2 | 11 | |
Proportion of bare spots and saline-alkali spots (%) | 0-2 | 14 |
Table 4 Evaluation positive index system of natural hay pasture degradation in north China (five-level) |
Indicator | Weight | Index score | |||||
---|---|---|---|---|---|---|---|
100 | 77.5 | 55 | 32.5 | 10 | |||
Average height (cm) | Temperate meadow steppe | 0.25 | >55 | 55-49.7 | 49.6-44.3 | 44.32-39 | <39 |
Temperate steppe | 0.25 | >46 | 46-41.3 | 41.32-36.7 | 36.6-32 | <32 | |
Mountain meadow | 0.25 | >50 | 50-45.7 | 45.6-41.3 | 41.32-37 | <37 | |
Low wetland meadow | 0.25 | >80 | 80-72 | 71-64 | 63-56 | <56 | |
Aboveground biomass (kg ha-1) | Temperate meadow steppe | 0.2 | >2000 | 2000-1532 | 1531-1064 | 1063-596 | <596 |
Temperate steppe | 0.2 | >1200 | 1200-936.7 | 936.6-673.3 | 673.2-410 | <410 | |
Mountain meadow | 0.2 | >1500 | 1500-1198.7 | 1198.6-897.3 | 897.2-596 | <596 | |
Low wetland meadow | 0.2 | >2500 | 2500-1998.7 | 1998.6-1497.3 | 1497.2-996 | <996 | |
Total coverage (%) | Temperate meadow steppe | 0.15 | >85 | 85-70 | 69-55 | 54-40 | <40 |
Temperate steppe | 0.15 | >60 | 60-48.7 | 48.6-37.3 | 37.2-26 | <26 | |
Mountain meadow | 0.15 | >90 | 90-77 | 76-64 | 63-51 | <51 | |
Lowland meadow | 0.15 | >98 | 98-85.7 | 85.6-73.3 | 73.2-61 | <61 | |
Proportion of medium grasses (%) | 0.1 | >50 | 50-36.7 | 36.6-23.3 | 23.2-10 | <10 | |
Litter biomass (kg ha-1) | 0.1 | >400 | 400-300 | 299-200 | 199-100 | <100 |
Table 5 Evaluation negative index system of natural hay pasture degradation in north China (five-level) |
Negative evaluation indicators | Weight | Index score | ||||
---|---|---|---|---|---|---|
100 | -10 | -35 | -60 | -85 | ||
Proportion of degradation-indicative plant (%) | 0.1 | 0-2 | 2.1-4.7 | 4.6-7.3 | 7.2-10 | >10 |
Proportion of sandy and saline-alkali spots (%) | 0.1 | 0-2 | 2.1-5.3 | 5.2-8.7 | 8.6-12 | >12 |
Table 6 Evaluation positive index system of natural hay pasture degradation in north China (seven-level) |
Positive indicator type | Weight | Index score | |||||||
---|---|---|---|---|---|---|---|---|---|
100 | 85 | 70 | 55 | 40 | 25 | 10 | |||
Average height (cm) | Temperate meadow steppe | 0.25 | >55 | 55-51.8 | 51.7-48.6 | 48.5-45.4 | 45.3-42.2 | 42.1-39 | <39 |
Temperate steppe | 0.25 | >46 | 46-43.2 | 43.1-40.4 | 40.3-37.6 | 37.5-34.8 | 34.7-32 | <32 | |
Mountain meadow | 0.25 | >50 | 50-47.4 | 47.3-44.8 | 44.7-42.2 | 42.1-36.6 | 39.5-37 | <37 | |
Low wetland meadow | 0.25 | >80 | 80-75.2 | 75.1-70.4 | 70.3-65.6 | 65.5-60.8 | 60.7-56 | <56 | |
Above-biomass (kg ha-1) | Temperate meadow steppe | 0.20 | >2000 | 2000-1719.2 | 1719.1-1438.4 | 1438.3-1157.6 | 1157.5-876.8 | 876.7-596 | <596 |
Temperate steppe | 0.20 | >1200 | 1200-1042 | 1041-884 | 883-726 | 725-568 | 567-410 | <410 | |
Mountain meadow | 0.20 | >1500 | 1500-1319.2 | 1319.1-1138.4 | 1138.3-957.6 | 957.5-776.8 | 776.7-596 | <596 | |
Low wetland meadow | 0.20 | >2500 | 2500-2199.2 | 2199.1-1898.4 | 1898.3-1597.6 | 1597.5-1296.8 | 1296.7-996 | <996 | |
Total coverage (%) | Temperate meadow steppe | 0.15 | >85 | 85-76 | 75-67 | 66-58 | 57-49 | 48-40 | <40 |
Temperate steppe | 0.15 | >60 | 60-53.2 | 53.1-46.4 | 46.3-39.6 | 39.5-32.8 | 32.7-26 | <26 | |
Mountain meadow | 0.15 | >90 | 90-82.2 | 82.1-74.4 | 74.3-66.6 | 66.5-58.8 | 58.7-51 | <51 | |
Lowland meadow | 0.15 | >98 | 98-90.6 | 90.5-83.2 | 83.1-75.8 | 75.7-68.4 | 68.3-61 | <61 | |
Litter biomass (kg ha-1) | 0.10 | >400 | 400-340 | 339-280 | 279-220 | 219-160 | 159-100 | <100 | |
Proportion of medium grasses (%) | 0.10 | >50 | 50-42 | 41-34 | 33-26 | 25-18 | 17-10 | <10 |
Table 7 Evaluation negative index system of natural hay pasture degradation in north China (seven-level) |
Negative indicator type | Weight | Index score | ||||||
---|---|---|---|---|---|---|---|---|
100 | -10 | -25 | -40 | -55 | -70 | -85 | ||
Proportion of degradation-indicative plant (%) | 0.1 | 0-2 | 2.1-3.6 | 3.7-5.2 | 5.3-6.8 | 6.9-8.4 | 8.5-10 | >10 |
Proportion of sandy and saline-alkali spots (%) | 0.1 | 0-2 | 2.1-4 | 4.1-6 | 6.1-8 | 8.1-10 | 10.1-12 | >12 |
Fig. 2 Distribution diagram of sampling plots of several types of natural hay pasture in the semi-arid region of north China |
Fig. 3 Score analysis diagram of five-level score and seven-level score evaluation index system |
Table 8 Results for positive indices and scores for degradation of natural hay pasture in north China |
Score | Indicator | 100 | 77.5 | 55 | 32.5 | 10 |
---|---|---|---|---|---|---|
Average height (cm) | Temperate meadow steppe | ≥55 | 55-47 | 47-40 | 40-32 | <32 |
Temperate steppe | ≥46 | 46-39 | 39-32 | 32-25 | <25 | |
Mountain meadow | ≥50 | 50-43 | 43-37 | 37-30 | <30 | |
Lowland meadow | ≥80 | 80-70 | 70-59 | 59-49 | <49 | |
Above-biomass (kg ha-1) | Temperate meadow steppe | ≥1800 | 1800-1440 | 1440-1080 | 1080-720 | <720 |
Temperate steppe | ≥1200 | 1200-960 | 960-720 | 720-480 | <480 | |
Mountain meadow | ≥1600 | 1600-1267 | 1267-933 | 933-600 | <600 | |
Lowland meadow | ≥2500 | 2500-2000 | 2000-1500 | 1500-1000 | <1000 | |
Coverage (%) | Temperate meadow steppe | ≥85 | 85-70 | 70-55 | 55-40 | <40 |
Temperate steppe | ≥60 | 60-49 | 49-37 | 37-26 | <26 | |
Mountain meadow | ≥90 | 90-77 | 77-64 | 64-51 | <51 | |
Lowland meadow | ≥98 | 98-86 | 86-73 | 73-61 | <61 | |
Proportion of medium grasses (%) | ≥50 | 50-37 | 37-23 | 23-10 | <10 | |
Litter biomass (kg ha-1) | ≥400 | 400-300 | 300-200 | 200-100 | <100 |
Table 9 Results for negative indices and scores for degradation natural hay pasture in north China |
Score | 100 | -10 | -35 | -60 | -85 |
---|---|---|---|---|---|
Proportion of degradation-indicative plant | 0-2 | 2-5 | 5-8 | 8-11 | ≥11 |
Proportion of bare spots and saline-alkali spots | 0-2 | 2-6 | 6-10 | 10-14 | ≥14 |
The authors have declared that no competing interests exist.
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