QX/T 90-2024 in English
VALIDTechnical requirements for tree ring sample collection
- Issued on:2024-06-20
- Implemented on:2024-10-01
- File Format:PDF
- Delivery:RFQ
| Standard No: | QX/T 90-2024 |
| Document status: | VALID |
| Title in English: | Technical requirements for tree ring sample collection |
| Title in Chinese: | 树轮样本采集技术要求 |
| Language: | English |
| File Format: | Electronic (PDF) |
| Delivery: | RFQ |
| Issued on: | 2024-06-20 |
| Implemented on: | 2024-10-01 |
| Chinese Classification: | A51-Quantity and Unit |
| Professional Classification: | QX-Meteorology |
| Related Keywords: | sample size
sample size tree-ring width analysis sample collection introduction background ≤2cm/min sample processing stage sample integrity rate |
Introduction
Background of Standard Revision and Technological Evolution
This revision is the first update of the QX/T90 standard since its first release in 2008, reflecting the progress of the research methodology of dendroclimatology in the past 16 years. The revision focuses on the elimination of traditional tools such as growth cones, and the standardization requirements of new analytical techniques such as tree ring grayscale, density, and stable isotopes.
Comparative Analysis of Core Changes
| Dimensions | 2008 Edition | 2024 Edition | Significance of Changes |
|---|---|---|---|
| Structural Framework | 10 Chapters + 2 Appendices | 6 Chapters + 2 Appendices | More compact logic |
| Terminology | 4 Terms | No clear definition | Unified with QX/T Series Standards |
| Sampling Technology | Disc Sampling | Cancelled | Protect tree ecology |
| Analysis type | Width analysis only | 5 types of analysis standards | More comprehensive technical coverage |
Analysis of key technical requirements
4.1 Sample site environment selection
The standard requires priority selection of areas with stable growing conditions (annual precipitation variation coefficient <15%) and human disturbance index <0.3, and recommends verifying vegetation continuity through the NDVI index.
5.2 Scientific Basis of Sample Size
Tree-ring Width Analysis requires a sample size of 20 trees × 2 cores, which is derived from the signal-to-noise ratio theory proposed by Fritts (1976): when the sample size reaches 40 cores, the proportion of climate signals can be increased to more than 85%. However, due to the high detection sensitivity of Stable Isotope Analysis, 4 trees can meet the requirements of δ13C analysis.
Implementation recommendations
- Sampling planning stage: It is recommended to select climate-sensitive areas in combination with historical meteorological data, and refer to the "China Tree Ring Climate Zoning"
- Field operation stage: When using the incremental growth cone, the drilling speed must be kept ≤2cm/min
- Sample processing stage: Grayscale and density samples should be immediately sealed and protected from light, and isotope samples should be frozen at -20℃
Standard application case
In the study of Tianshan spruce tree rings, after adopting this standard:
- The sample integrity rate increased from 78% to 93%
- The climate response function R2 increased by 0.12
- The cross-dating error rate decreased by 40%
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