HJ 1167-2021National Ecological Status Survey and Evaluation Technical Specifications-Field Observation of Forest Ecosystem (English PDF)

7.1 Plot selection

7.1.1 The selection of sample plots should be representative and typical, and avoid the selection of sample plots in areas with unclear ownership and frequent changes.

7.1.2 The field sampling rate is an average of 1 fixed sample plot per 10 000 km2.It is recommended to select the existing sample plot as the fixed sample Consider representation, economy, feasibility, etc., and make appropriate arrangements according to the actual situation of each region, such as in areas where ecosystem types are staggered and complex.

The number of sample plots can be appropriately increased in the domain, and the number of sample plots can be appropriately reduced in the area with a single type.

7.1.3 For the observation object, if possible, select at least 2 sample plots that can represent the observation object, the surface coverage is relatively uniform, the sample area is 10,000 m2.

7.1.4 The sample plot should be selected on the flat land with the same ecosystem type or on the slope with relatively uniform gentle slope.

7.2 Layout of plots

7.2.1 The plots should reflect the changing characteristics of various forest ecosystems with terrain, soil and human environment, etc.

For 2 replicated quadrats, the size of the quadrat is set according to different climate zones and forest types, generally 20 m × 20 m, and the shrub quadrature is 20 m × 20 m.

10m x 10m.

7.2.2 For homogeneous ground sample plots, simple random sampling should be performed in the area instead of the overall distribution.

7.2.3 For non-uniform ground sample plots, stratified sampling should be carried out according to the degree of spatial heterogeneity within the sample plot, requiring relatively uniformity within the stratum, and sampling within the stratum.

Local uniform sampling is carried out within the layer to express the parameters of each layer.

7.2.4 In order to investigate the growth status of forest understory vegetation (species, vegetation height, coverage, biomass, etc.) Arrange no less than 4 understory vegetation quadrats with an area of not less than 1 m2, and try not to arrange them at the edge of the quadrats.

9.1 Altitude

Can be extracted using a Digital Elevation Model (DEM) or measured by GPS.

9.2 Terrain types

Using the observation method, it is divided into plains, hills and mountains, which can be refined and remarked on this basis according to the actual situation. The types are as follows.

a) Plain. flat and open, and the relative height difference is less than 50 m;

b) Hills. there is no obvious vein, the slope is gentle, and the relative height difference is less than 100 m;

c) Mountainous area. the undulations are large, the peaks and valleys are obvious, the elevation is above 500 m, and the relative height difference is above 100 m.

9.3 Slope

The slope can be extracted with a digital elevation model (DEM) or measured with tools such as a compass.

as follows.

a) Grade I is a flat slope. 0°~5°;

b) Grade II is gentle slope. 5°~15°;

c) Grade III is slope. 15°~25°;

d) Grade IV is steep slope. 25°~35°;

e) Grade V is a steep slope. 35°~45°;

f) Grade VI is dangerous slope. above 45°.

9.4 Aspect

The aspect can be extracted using a digital elevation model (DEM) or measured with tools such as a compass. It is divided into eight directions (upper and lower not included).

as follows.

a) North slope. azimuth angle 337°~360°, 0°~22°;

b) Northeast slope. azimuth angle 22°~67°;

c) East slope. azimuth angle 67°~112°;

d) Southeast slope. azimuth angle 112°~157°;

e) South slope. azimuth angle 157°~202°;

f) Southwest slope. azimuth angle 202°~247°;

g) West slope. azimuth angle 247°~292°;

h) Northwest slope. azimuth angle 292°~337°.

9.5 Slope

Using the observation method, the slope positions are divided into six positions. ridge, upslope, mid-slope, downslope, valley, and flat, as follows.

a) Ridge. the dividing line of the mountain range and the range of 15 m vertical height on both sides of it;

b) Uphill. from below the ridge to the uppermost part of the hillside after three equal parts within the valley;

c) Middle slope. the middle slope of three equal parts;

d) Downhill. three equal downhill positions;

e) Valley (or mountain depression). the valley on both sides of the catchment line, if the sample plot is located in a local depression in other parts, it should also be recorded as a valley;

f) Flatlands. Lot of plains or mesas.

9.6 Soil types

According to the soil texture, the soil is divided into three categories. sandy soil, clay soil and loam soil.

It can be refined and remarked on this basis according to the actual situation.

9.7 Humus Thickness

According to the thickness, it is divided into three grades. thick, medium and thin, as follows.

a) Thickness. >5 cm;

b) Medium. 2 to 5 cm;

c) Thin.