Responses of Vegetation Growth to Climatic Factors in Shule River Basin in Northwest China: A Panel Analysis
Abstract
:1. Introduction
2. Overview of the Study Region
3. Data Sources and Methodology
3.1. Data Sources and Processing
3.2. Research Methodology
3.2.1. Linear Trend Analysis
3.2.2. Multiple Correlation Analysis
3.2.3. Mann–Kendall (M-K) Trend Detection
3.2.4. Panel Data Regression
4. Results
4.1. Quantity Characteristic of Vegetation Coverage
4.2. Spatial Characteristics of Vegetation Change
4.3. Correlation between Vegetation Variation and Climatic Factors
4.3.1. Multiple Correlation between Vegetation Variation and Climatic Factors
4.3.2. Trends of NDVI and Climatic Factors in a Year
4.4. Impact of Climatic Change on NDVI
4.4.1. The Overall Effect of the Panel Regression Models
4.4.2. Contribution of Climatic Change to NDVI
4.4.3. Individual-Specific Effect in Phase and Year
4.4.4. Coefficients Variation with Phase
5. Discussion and Conclusions
5.1. Discussion
5.2. Conclusions
Acknowledgments
Author Contributions
Conflicts of Interest
References
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NDVIgs Trends | High Significance p ≤ 0.01 | Significance 0.01 < p ≤ 0.1 | No Significance p > 0.1 | Summary |
---|---|---|---|---|
Moderate degradation (−0.03 < θ < −0.02) | 0.4363 | 0.5849 | 0.2585 | 1.2797 |
Slight degradation (−0.02 ≤ θ < 0) | 0.0569 | 0.4376 | 5.4947 | 5.9892 |
No change (θ = 0) | - | - | 0.0283 | 0.0283 |
Slight improvement (0 < θ < 0.02) | 31.254 | 32.2391 | 28.7498 | 92.2429 |
Moderate improvement (0.02 ≤ θ < 0.04) | 0.4597 | - | - | 0.4597 |
High improvement (0.04 ≤ θ < 0.05) | 0.0002 | - | - | 0.0002 |
Summary | 32.2071 | 33.2616 | 34.5313 | 100 |
Degradation (θ < 0) | No Change (θ = 0) | Improvement (θ > 0) | Summary | |
---|---|---|---|---|
Guazhou | 1.41 | 0.00 | 5.88 | 7.29 |
Dunhuang | 0.62 | 0.00 | 4.26 | 4.87 |
Yumen | 0.97 | 0.00 | 9.09 | 10.06 |
Tianjun | 3.09 | 0.01 | 15.84 | 18.94 |
Subei (southern part) | 1.01 | 0.01 | 44.74 | 45.76 |
Subei (northern part) | 0.14 | 0.00 | 4.03 | 4.17 |
Aksai | 0.03 | 0.00 | 8.87 | 8.90 |
Summary | 7.27 | 0.03 | 92.70 | 100.00 |
Degradation (θ < 0) | No Change (θ = 0) | Improvement (θ > 0) | Summary | |
---|---|---|---|---|
Grassland | 4.27 | 0.02 | 48.94 | 53.23 |
Shrubland | 0.11 | 0.00 | 0.74 | 0.86 |
Wetland | 0.25 | 0.00 | 1.25 | 1.50 |
Cultivated land | 0.99 | 0.00 | 4.32 | 5.31 |
Bareland | 1.55 | 0.01 | 37.22 | 38.78 |
Artificial surfaces | 0.10 | 0.00 | 0.21 | 0.30 |
Permanent snow and ice | 0.00 | 0.00 | 0.02 | 0.02 |
Summary | 7.27 | 0.03 | 92.70 | 100.00 |
R | F-Statistic | Probability | ||
---|---|---|---|---|
Upstream | Current | 0.7984 | 8.7902 | 0.0063 |
Lag phase 1 | 0.9680 | 74.4811 | 0.0000 | |
Lag phase 2 | 0.9262 | 30.1908 | 0.0001 | |
Lag phase 3 | 0.6934 | 4.6294 | 0.0377 | |
Lag phase 4 | 0.4467 | 1.2463 | 0.3286 | |
Downstream | Current | 0.6889 | 4.5157 | 0.0401 |
Lag phase 1 | 0.9252 | 29.7200 | 0.0001 | |
Lag phase 2 | 0.9809 | 126.9627 | 0.0000 | |
Lag phase 3 | 0.8335 | 11.3765 | 0.0027 | |
Lag phase 4 | 0.6313 | 3.3130 | 0.0787 |
LLC | Breitung | IPS | Fisher | HT | ||
---|---|---|---|---|---|---|
NDVI | upstream | −8.0570 *** | −6.6448 *** | −5.7781 *** | −8.7002 *** | 0.1909 *** |
downstream | −4.4107 *** | −1.5658 ** | −2.4993 *** | −2.4852 *** | 0.6760 *** | |
Precipitation | upstream | −5.7606 *** | −9.4949 *** | −9.4238 *** | −5.1822 *** | −0.1524 *** |
downstream | −7.7871 *** | −8.7712 *** | −8.3680 *** | −3.3978 *** | −0.0013 *** | |
Accumulated temperature | upstream | −6.2357 *** | −7.3473 *** | −7.0134 *** | −6.1442 *** | −0.0515 *** |
downstream | −5.9864 *** | −8.0651 *** | −8.1293 *** | −6.5662 *** | −0.0535 *** | |
Temperature | upstream | −8.9307 *** | −6.7161 *** | −8.8995 *** | −6.2323 *** | −0.0939 *** |
downstream | −7.4510 *** | −7.9551 *** | −8.6820 *** | −6.8601 *** | −0.1733 *** |
No. | Model | Cons | Pre | Atem | R2 | χ2 | F |
---|---|---|---|---|---|---|---|
1 | OLS | 0.08029 *** (0.00164) | 0.00040 ** (0.00017) | 0.00047 *** (0.00002) | 0.8096 | 775.85 *** | |
2 | FE | 0.12000 *** (0.00527) | 0.00018 (0.00013) | 0.00003 (0.00006) | 0.8624 | 1.19 | |
3 | BE | 0.07961 *** (0.00566) | −0.00012 * (0.00168) | 0.00053 ** (0.00020) | 0.8697 | 66.76 *** | |
4 | LSDV | 0.07928 *** (0.00313) | 0.00018 (0.00014) | 0.00004 (0.00005) | 0.9447 | 170.13 *** | |
5 | FE_TW | 0.11352 *** (0.00377) | 0.00013 (0.00009) | 0.00002 (0.00004) | 0.8613 | 3669.19 *** | |
6 | RE | 0.09402 *** (0.00472) | 0.00030 *** (0.00010) | 0.00032 *** (0.00003) | 0.8690 | 115.50 *** | |
7 | FGLS | 0.09589 *** (0.00546) | 0.00035 ** (0.00016) | 0.00029 *** (0.00005) | 0.8687 | 54.28 *** | |
8 | MLE | 0.10613 *** (0.00889) | 0.00028 *** (0.00011) | 0.00018 *** (0.00006) | 13.92 *** | ||
9 | PCSE | 0.08308 *** (0.00283) | 0.00025 ** (0.00011) | 0.00048 *** (0.00001) | 0.8515 | 217.90 *** | |
10 | 2S-GMM | 0.11213 *** (0.00060) | 0.00028 *** (0.00003) | 0.00011 *** (0.000005) | 0.8096 | 446.47 *** |
No. | Model | Cons | Pre | Atem | R2 | χ2 | F |
---|---|---|---|---|---|---|---|
1 | OLS | 0.09791 *** (0.00269) | 0.00092 * (0.00047) | 0.00034 *** (0.00001) | 0.6993 | 424.33 *** | |
2 | FE | 0.14486 *** (0.00527) | 0.00071 ** (0.00027) | 0.00006* (0.00003) | 0.7460 | 7.27 *** | |
3 | BE | 0.09870 *** (0.01072) | −0.00182 (0.00732) | 0.00037 *** (0.00010) | 0.7527 | 30.44 *** | |
4 | LSDV | 0.10211 *** (0.00319) | 0.00071 ** (0.00029) | 0.00006 (0.00004) | 0.9379 | 175.24 *** | |
5 | FE-TW | 0.13509 *** (0.00476) | 0.00039** (0.00015) | 0.00003 (0.00002) | 0.7463 | 165.24 *** | |
6 | RE | 0.128991 *** (0.00724) | 0.00069 *** (0.00015) | 0.00016 *** (0.00002) | 0.7502 | 55.67 *** | |
7 | FGLS | 0.118130 *** (0.00650) | 0.00092 *** (0.00030) | 0.00022 (0.00003) | 0.7503 | 56.42 *** | |
8 | MLE | 0.12105 *** (0.01070) | 0.00090 *** (0.00024) | 0.00020 *** (0.00004) | 24.41 *** | ||
9 | PCSE | 0.10313 *** (0.00290) | 0.00081 *** (0.00016) | 0.00022 *** (0.00003) | 0.8162 | 68.87 *** | |
10 | 2S-GMM | 0.13437 *** (0.00635) | 0.00176 *** (0.00017) | 0.00008 ** (0.00004) | 187.51 *** |
FE | RE | Difference | Std. Err. | |
---|---|---|---|---|
Constant | 0.1199954 | 0.958935 | 0.0241019 | - |
Precipitation | 0.000175 | 0.0003507 | −0.0001757 | 0.0000291 |
Temperature | 0.000035 | 0.000293 | −0.0002582 | 0.0000414 |
Region | Constant (αi) | Precipitation (β0) | Temperature (β0) | χ2 (Wald) | χ2 (Test of Parameter Constancy) |
---|---|---|---|---|---|
Upstream | 0.112663 *** (0.011126) | −0.0001927 (0.000469) | 0.000979 (0.000687) | 2.33 | 1307.78 *** |
Downstream | 0.134833 *** (0.012624) | 0.000188 0.0005347 | 0.001483 *** 0.0005626 | 6.53 ** | 2454.42 *** |
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Qi, J.; Niu, S.; Zhao, Y.; Liang, M.; Ma, L.; Ding, Y. Responses of Vegetation Growth to Climatic Factors in Shule River Basin in Northwest China: A Panel Analysis. Sustainability 2017, 9, 368. https://doi.org/10.3390/su9030368
Qi J, Niu S, Zhao Y, Liang M, Ma L, Ding Y. Responses of Vegetation Growth to Climatic Factors in Shule River Basin in Northwest China: A Panel Analysis. Sustainability. 2017; 9(3):368. https://doi.org/10.3390/su9030368
Chicago/Turabian StyleQi, Jinghui, Shuwen Niu, Yifang Zhao, Man Liang, Libang Ma, and Yongxia Ding. 2017. "Responses of Vegetation Growth to Climatic Factors in Shule River Basin in Northwest China: A Panel Analysis" Sustainability 9, no. 3: 368. https://doi.org/10.3390/su9030368