**Section II: Survey Design**
Survey design is a critical task that must be completed before any harvesting operations begin. It serves as the foundation for forest harvesting and plays a vital role in ensuring efficient and sustainable forest management. Proper survey and design work helps reduce operational blindness, minimize waste, and improve overall productivity. The survey design must be conducted by a qualified professional team to ensure accuracy and compliance with industry standards.
The main steps in the harvesting design process include:
**I. Field Investigation**
**(A) Stand Inspection**
Before conducting any surveys, it is essential to inspect the forest stand thoroughly. This includes understanding the orientation of the small class, the distribution of trees, previous operations, tree height, diameter at breast height (DBH), density, and the condition of the forest. This information provides valuable reference data for investigators and allows internal teams to assess whether the design parameters are reasonable. During fieldwork, all surveying groups should maintain constant communication to avoid inconsistencies and ensure the accuracy of the design.
**(B) Sample Layout**
Based on the stand conditions, square or circular plots can be established in smaller, uniform, and well-organized areas. Larger or more complex stands typically use strip samples. A starting point is selected on the edge of the forest for GPS positioning, serving as the beginning of the mechanical layout. This point must allow the sample strip to cross the entire small class effectively.
Sample belts are usually 6 meters wide and 50 meters long, covering an area of approximately 0.45 mu. The sampling rate should be at least 5%. For forests less than 100 mu, a "V" or "inverted V" shaped belt is used, while forests between 100 and 200 mu may use an "M" shape with a polyline. For larger areas over 300 mu, additional fold lines are added to ensure full coverage and an accuracy of over 90%.
Transect placement should consider the upper, middle, and lower parts of the stand. Due to human activity, the lower part of the slope often has sparse tree density, while the upper portion may have issues like poor measurement, small diameters, or low-quality materials. Balancing these sections helps avoid large errors in volume and material structure, improving the overall design accuracy. If the volume accuracy exceeds 90%, it is considered acceptable; otherwise, additional sample zones should be added to meet the required precision.
**(C) Sample Survey**
1. **Tree Measurement**: For each tree, a 50-meter measuring tape is used, with 3 meters on each side, and a 3-meter ruler is employed for accurate measurements. A 1.3-meter scale is marked on the rod to determine DBH and measure it precisely.
Trees with a DBH below 5 meters are recorded separately but not included in the stand factor or production calculations. Each wooden ruler must be fully measured, and for older forests with damaged bark, inspections are conducted to adjust for accuracy.
2. **Visual Inspection**: Material design is primarily based on visual assessment. Factors such as trunk height, dryness, sharpness, and branch thickness are considered, following the principle of producing marketable products, prioritizing longer pieces, and focusing on high-demand materials. For clear-cutting, dense stands may allow normal design of small poles, while remote areas require careful control of product types.
For trees with a dry bending of more than 3%, longer pieces are prioritized, and short materials are minimized. Logs, beams, and other components are separately categorized during the design process.
When visually measuring, after determining the DBH, the curvature of the trunk is assessed to decide whether it qualifies as commercial or non-commercial material. The length of the wood, seed head diameter, and final material length (typically 50–75% of the tree height) are also noted. For building materials, the trunk is directly cut, while for other cases, the diameter of smaller materials is estimated to ensure accurate design.
3. **Tree Cutting**: Based on the operating area and method, each small class must cut down 3 to 7 trees for growth rate analysis and material design. Clear-cutting operations involve 3 trees for less than 100 mu, 5 for 100–200 mu, and 7 for over 200 mu. For tending operations, 3 trees are cut for under 200 mu, and 5 for over 200 mu.
After cutting, the average DBH, tree height, and dryness are calculated. A standard tree representing the average condition of the stand is selected for growth and material design. Other trees are chosen based on deviations from the average DBH, ensuring symmetry and equal numbers on both sides. For example, if the average DBH is 14.2 cm, three trees could be selected at 12 cm, 14 cm, and 16 cm. For five trees, the selection would be at 10, 12, 14, 16, and 18 cm, and so on.
Cut trees must be located in the upper, middle, and lower parts of the stand, and at least 8 meters away from the forest edge.
**(D) Area Measurement and Job Design Drawing**
1. **Area Measurement**: The actual boundary and area of the forest must be measured accurately for the design. The closing difference should not exceed 1%, otherwise the measurement must be repeated. The director of the forestry area or a forest patrol officer must be present during the measurement. In state-owned or cooperative forests, relevant documents such as maps, topographic maps, and ownership agreements must be reviewed to confirm boundaries, especially for collective forests.
It is strictly prohibited to measure multiple small classes together. The starting point is marked using a handheld GPS.
2. **Job Design Drawing**: Using forest phase maps, topographic maps, and field survey data, job design drawings are created. Natural objects, boundaries, and nearby features are clearly described and sketched on-site. If necessary, GPS is used for precise location marking. Computer mapping is used to calculate the area and mark all details on the map. Once approved, the design scheme, cutting license, and site markings serve as the basis for forest operations.
All boundaries around the design area must be clearly marked. If the small class is isolated, the marking is placed outside the forest; otherwise, it is inside the designated area. After construction, the forest farm is marked on the root of the felled trees.
**Second, Industry Design**
Based on the Hebei Forest Management Technical Specifications (Trial) and the field survey results, internal design is carried out.
1. **Schedule 1**: The actual measured area of the operating zone is recorded, and all vacant land within the forest and its margins must be deducted. The small class account is registered in parallel. The stand type is determined through on-site surveys, including slope position, direction, soil depth, and herbaceous undergrowth. This ensures accuracy for future redesigns.
The age of the forest is verified using a ledger or standard wood. Species composition is dominated by the main tree species. If a species accounts for 2–5%, it is marked with a "+", and less than 2% is marked with a "-".
The number of acres is calculated by dividing the total number of plots by the plot area. The average DBH is obtained from statistical summaries, with a weighted average using the number of trees as weight, accurate to 0.1 cm. The volume per mu is calculated by dividing the total volume by the plot area.
Growth volume is filled in based on the analytical wood results.
Closed degree is surveyed using the rope statistics method, with one sample point every 5 meters. The percentage of canopy coverage is calculated using the formula PC = U/N, where U is the number of points within the canopy and N is the total number of points.
2. **Schedule 2**: Log books and foreign trader-designed logs are registered in the bar product column of Table 2, alongside waste wood. The export rate of commercial materials is calculated accordingly.
3. **Schedule 3**: Based on operation difficulty and cost quotas, revenue and expenditure are determined according to the site conditions.
4. **Schedule 4**: Manual updating is used, with the updated area matching the design forest area (not less than the original sub-class cutting area). The forest type, slope, elevation, soil depth, and understory must be accurately surveyed. Tree species and their allocation depend on the site conditions. Mixed forests of larch, spruce, and broad-leaved trees are encouraged to maximize benefits.
**Third, Design Accuracy Index**
- Area error within ±5%.
- Accumulation accuracy over 90%.
- Commercial material error within 5%.
- By-product error within ±20%.
- Number of acres error within 5%.
- DBH error within ±0.2 cm.
Through field investigations, internal calculations, and the preparation of job design programs, the work is publicized weekly as a unit. After receiving no objections, the plan is submitted for approval before implementation.
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