采用基于多指标的决策树分类方法制作。
\n1.生态系统不稳定性指数 = 植被变异系数 * 风蚀强度归一化指数
\n其中：
\n植被变异系数：
\n利用1982-2013年的AVHRR GIMMS数据集、2000年以来的MODIS MOD13Q1数据集，根据研究区范围进行统一的裁切、投影转换、数据融合等处理，基于CASA（Carnegie-Ames-Stanford approach）模型模拟研究区净初级生产力（Net Primary Productivity，NPP）值，反演获得研究区1982.01-2016.12的NPP数据集，进一步计算获得研究区植被变异系数。
\n风蚀强度归一化指数：
\n依据修正的土壤风蚀模型（RWEQ）模拟计算的研究区1982-2016年多年平均土壤风蚀强度，通过去量纲计算了研究区土壤风蚀强度归一化指数，作为土壤稳定性评价的主要量化指标。
\n2.生态系统稳定性程度 = 植被稳定性综合指数 * 风蚀强度归一化指数
\n其中：
\n植被稳定性综合指数：
\n对1982-2016年时间序列NPP计算得到植被的恢复力指数、植被对干旱与温度的阻抗性指数以及植被变异系数，按照恢复性、阻抗性和时间稳定性合成计算，得到植被综合稳定性指数。", "ds_source": "
采用基于多指标的决策树分类方法制作。", "ds_process_way": "
采用基于多指标的决策树分类方法制作。", "ds_quality": "
数据质量良好", "ds_acq_start_time": "2020-01-01 00:00:00", "ds_acq_end_time": "2020-12-31 00:00:00", "ds_acq_place": "北方半干旱区", "ds_acq_lon_east": 127.0, "ds_acq_lat_south": 35.5, "ds_acq_lon_west": 104.0, "ds_acq_lat_north": 50.5, "ds_acq_alt_low": null, "ds_acq_alt_high": null, "ds_share_type": "apply-access", "ds_total_size": 4368571, "ds_files_count": 2, "ds_format": "tif", "ds_space_res": "1000m", "ds_time_res": "", "ds_coordinate": "WGS84", "ds_projection": "", "ds_thumbnail": "9ee0776f-c53c-4ba1-be79-cccffaef87ae.jpg", "ds_thumb_from": 2, "ds_ref_way": "", "paper_ref_way": "", "ds_ref_instruction": "用户在使用数据时请在正文中明确声明数据的来源，并在参考文献部分引用本元数据提供的引用方式。", "ds_from_station": null, "organization_id": "8534e8f7-cbd5-4771-81d6-d524ffde0065", "ds_serv_man": "敏玉芳", "ds_serv_phone": "0931-4967596", "ds_serv_mail": "ncdc@lzb.ac.cn", "doi_value": "10.12072/ncdc.ZDYF.db1682.2022", "subject_codes": [ "170.4510" ], "quality_level": 3, "publish_time": "2022-04-18 11:33:34", "last_updated": "2022-04-24 17:17:37", "protected": false, "protected_to": "2024-01-13 00:00:00", "lang": "zh", "cstr": "11738.11.ncdc.ZDYF.db1682.2022", "i18n": { "en": { "title": "Spatial distribution of ecosystem stability in semi-arid areas of northern China", "ds_format": "", "ds_source": "
<p> The decision tree classification method based on multi index is used to make.\n <p> Good data quality\n\nThe decision tree classification method based on multi index is adopted
1. Ecosystem instability index = vegetation variation coefficient * normalized index of wind erosion intensity
Where:
Coefficient of variation of vegetation:
AVHRR GIMMS data set from 1982 to 2013 and MODIS mod13q1 data set since 2000 are used to carry out unified cutting, projection conversion and data fusion according to the scope of the study area. The net primary productivity (NPP) value of the study area is simulated based on CASA (Carnegie Ames Stanford approach) model, and the NPP data set from January 1982 to December 2016 is retrieved, The coefficient of variation of vegetation in the study area was obtained by further calculation
Normalized index of wind erosion intensity:
According to the multi-year average soil wind erosion intensity in the study area from 1982 to 2016 simulated and calculated by the modified soil wind erosion model (rweq), the normalized index of soil wind erosion intensity in the study area is calculated through dimensionless calculation, which is used as the main quantitative index for soil stability evaluation
2. Degree of ecosystem stability = comprehensive index of vegetation stability * normalized index of wind erosion intensity
Where:
Comprehensive index of vegetation stability:
For the 1982-2016 time series NPP, the vegetation resilience index, vegetation resistance index to drought and temperature and vegetation variation coefficient are calculated, and the vegetation comprehensive stability index is obtained according to the synthetic calculation of resilience, resistance and time stability.
", "ds_time_res": "", "ds_acq_place": "Northern semi-arid region", "ds_space_res": "1000m", "ds_projection": "", "ds_process_way": " <p> The decision tree classification method based on multi index is used to make.\n