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To explore the ecological stoichiometric characteristics of C, N and P in leaves of Fraxinus mandshurica from different provenances, and to provide scientific basis for the selection and cultivation of excellent sources of Fraxinus mandshurica, four excellent provenances (Dongfanghong, Tangwanghe, Huinan and Maoershan (compare)) of Fraxinus mandshurica from Maoershan Experimental Forest Farm of Northeast Forestry University were selected as research objects. The seasonal dynamics of C, N and P contents of Fraxinus mandshurica from different provenances, and the allometry relationship of C, N and P contents were analyzed. The results showed that the N and P content of Fraxinus mandshurica leaves gradually decreased during the growing season, the C/N and C/P gradually increased. The N/P increased first and then decreased. There were significant differences in the content of N, P, C/N and C/P in leaves of different provenances at the early growth stage and the flourishing stage. The content of C and N/P were not significantly different in the growing season. The C, N and P contents in the leaves of Fraxinus mandshurica from four provenances had a significant allometric growth relationship. The allometric growth constant of Dongfanghong provenance was significantly different from other provenances. It was forming its own nutrient balance and utilization strategy. The N content of Huinan provenances was higher than that of other provenances, and the C/N and N/P were lower than that of other provenances. It had higher nutrient utilization efficiency. During cultivation process, the nitrogen fertilizer should be applied at the early growth stage of Fraxinus mandshurica and phosphate fertilizer should be applied at the flourishing stage to improve the nutrient utilization efficiency and promote its rapid growth. [ABSTRACT FROM AUTHOR]

The effects of forest management methods on the understory litter and soil water conservation capacity of Larix principisrupprechtii forests of different ages were studied to provide a theoretical basis for the formulation of Larix principis-rupprechtii plantation management and soil and water conservation measures in the study area. In August 2021, young forests, near-mature forests and mature forests of Larix principis-rupprechtii under near-natural management, conventional management and non-management measures were selected as the research objects in Wangyedian Forest Farm, Chifeng City, the method of field survey and sampling combined with indoor experimental analysis was used to compare and analyze the water holding capacity of understory litter and soil in young Larix principis-rupprechtii forest, near-mature forest and mature forest under different management methods, and the entropy weight method was used to comprehensively evaluate the litter and soil water conservation capacity of Larix principis-rupprechtii forest. The results showed that: the total thickness of litter in 9 sample plots ranged from 2. 37 cm to 5. 83 cm, and the total volume of litter ranged from 11. 27 t / hm 2 to 37. 07 t / hm 2 . The maximum and effective water holding capacity of litter under different ages of Larix principis-rupprechtii forests showed the trend of mature forest>near-mature forest>young forest. The maximum and effective water holding capacity of litter under Larix principis-rupprechtii forest under different management modes showed the order of non-management>conventional management> near natural management. Soil total porosity, capillary porosity, saturated water capacity and capillary water capacity under different ages of Larix principis-rupprechtii stands had the regularities of young forest>mature forest>near-mature forest. Soil porosity and water holding capacity of Larix principis-rupprechtii forest under different management patterns showed the change rule of near-natural management>conventional management>non-management. Under non-management measures, the understory water conservation capacity of mature forest stage of Larix principis-rupprechtii forest was the highest; under conventional management measures, the understory water conservation capacity of young forest stage was second, and the understory water conservation capacity of near-mature forest stage under conventional management measures was the lowest. [ABSTRACT FROM AUTHOR]

The research objective is to reveal the effects of thinning intensity with crop tree management and environmental factors on natural regeneration of the mixed stands of Pinus massoniana and Quercus variabilis, so as to provide a scientific basis cultivating multifunctional forests of close-to-nature characteristics. By following crop tree management, 28 quadrats of 5 m×5 m were established in four intensities: weak thinning WT (7. 6%), light thinning LT (15. 3%), moderate thinning MT (24. 3%), and control (CK). The regeneration species richness, species diversity, regeneration density, regeneration frequency, seedling height growth difference at different thinning intensities, and the impact of environmental factors and stand factors on natural regeneration in three different years were analyzed. The result showed that in three consecutive years, 33 natural regeneration species of 23 families and 31 genera, rily prima- broad-leaved species, were recorded; the species richness of natural regeneration at different thinning intensities was greater than CK; and the intrinsic diversity in the following three years after the different thinning was MT>LT>WT>CK. In different years after thinning, there were significant and extremely significant differences in regeneration density between MT and CK (P<0. 05 and P< 0. 01). The mean value of regeneration frequency under different thinning intensities in 3 years was higher than that of CK. The ling seed- height was greater than that of CK at different thinning intensities; increasing the thinning intensity promoted seedling height growth. The canonical correlation analysis between the regeneration group and environmental group revealed that the greater thinning tensity in- together with the gentler slope increased the natural regeneration density and the species richness. The research revealed that the increase of thinning intensity can escalate species richness, species diversity, regeneration density and regeneration frequency, with HT the best, the synergistic negative effect of slope, aspect may offset the positive effect of thinning intensity on natural regeneration to a certain extent, and that the corresponding management countermeasures should be further studied in future management practice. [ABSTRACT FROM AUTHOR]

In order to explore the influence of different feature selection methods and estimation models on canopy closure estimation of natural secondary forests, 63 (0. 09 hm²) sample plots in Maoershan Experimental Forest Farm were taken as the research area, and Airborne Laser Scanning (ALS) data was used to extract features. Three feature selection methods (Pearson correlation analysis, Random Forest (RF) and Boruta)) and three models (Partial Least Squares Regression (PLSR), Random Forest Regression (RFR) and Support Vector Regression (SVR)) were employed to estimate canopy closure, and the accuracy evaluation and analysis of variance (ANOVA) of the model were carried out by fisheye photo method and sample method. The results showed that the accuracy of PLSR was the highest and SVR was the lowest. The estimation accuracy of RF and Boruta algorithm was higher than Pearson correlation analysis. The PLSR model after Boruta feature selection had the highest accuracy (R² = 0. 451 1, RMSE = 0. 067 5). The feature selection of fisheye photo and sample method, model fitting method of the fisheye photo had no significant effect, yet the model of sample method had a significant effect on estimating canopy closure. The results indicated that the accuracy of PLSR was better than others. The model of the sample method had a significant effect on canopy closure. ALS can effectively estimate the canopy closure of natural secondary forests, which provided a basis for large-scale estimation. [ABSTRACT FROM AUTHOR]

This article uses the 2020 L-band fully polarized ALOS-2 of the Saihanba Mechanical Forest Farm in Hebei Province as the data source, and mainly classify larch forests, broad-leaved forests, mixed coniferous forests, etc., compares the classification accuracy of 7 kinds of ground objects by three schemes of multi-temporal polarization decomposition combined with interference coherence, single-temporal polarization decomposition and single-temporal polarization decomposition combined with interference coherence. The methods are as followed: (1) calculate 12 polarization decomposition methods (81 polarization decomposition features) for each time-phase full polarization data; (2) combining the backscattering coefficient and interference coherence with the selected polarization decomposition features respectively, three classification schemes are obtained, and the features involved in the classification are screened according to their importance combined with the random forest classifier; (3) determining the best classification scheme for land cover types within the study area. The results show that: under temporal stage, according to the importance of the selected features, the features participating in the classification are increased, and the overall classification accuracy first increases and then stabilizes. The temporal information can improve the polarization decomposition classification accuracy of polarimetric SAR images. The overall classification accuracy and Kappa coefficient increase from 87. 33% and 0. 851 0 to 90. 41% and 0. 887 5, respectively. Combined with random forest classifier for feature screening, 102 classification features in 5 phases are obtained, and the best classification accuracy is obtained (the overall classification accuracy is 93. 84%, and the Kappa coefficient is 0. 927 6). Multi-temporal interferometric coherence combined with multi-temporal polarization decomposition can effectively improve the identification accuracy of land cover types and can also provide a reference for the rapid identification of stand types. [ABSTRACT FROM AUTHOR]

In order to understand the genetic diversity and change trend of Larix olgensis production groups, and to provide scientific basis for collection, protection and multi-generation genetic improvement of L. olgensis excellent breeding resource, 30 pairs of primers with high polymorphism were selected from 270 pairs of Pinaceae SSR universal primers, and 105 individual plants of L. olgensis seed orchard in Linkou Qingshan forest farm were analyzed by SSR molecular markers. The results showed that a total of 258 pairs of alleles were detected with 30 pairs of primers, the average number of observed alleles（Na） was 2.833, the average number of effective alleles（Ne） was 1.814, the average observed heterozygosity（Ho） was 0.404, and the average expected heterozygosity（He） was 0.401. The inbreeding coefficient in population(Fis) and total inbreeding coefficient in population(Fit) were negative, indicated a slight heterozygote excess and no inbreeding decline. The Shannon diversity index（I） was 0.694, and the polymorphism information content（PIC） was 0.354 1, exhibited a high genetic diversity and genetic variation was mainly within the population. The UPGMA cluster diagram took 0.692 as the threshold and divided the 105 individual plants into four groups. The SSR primers for this study have good versatility, the genetic diversity of L. olgensis seed orchard is high, and the genetic variation level of clonal population is not reduced. [ABSTRACT FROM AUTHOR]

To understand the changes of NSC in trees after fertilization, the 15-year-old Fraxinus mandshurica plantation was selected for nitrogen and phosphorus addition in Xiaojiu Forest Farm in Shangzhi City, Heilongjiang Province. The nitrogen and phosphate fertilizer was set at 4 levels（N0:0 g/m², N1:5 g/m², N2:12.5 g/m², N3:20 g/m²）, and 3 levels（P0:0 g/m², P1:7.5 g/m², P2:15 g/m²） respectively. There was a total of 12 treatments of combined application of nitrogen and phosphate fertilizers. The net photosynthetic rate, chlorophyll, total nitrogen, total phosphorus, and non-structural carbohydrate（NSC） concentration of leaves and fine roots were measured at the 3 rd year after fertilization. The results showed that: N and P fertilization led to an increase in the net photosynthetic rate and concentrations of chlorophyll a, chlorophyll b and total chlorophyll of F. mandshurica leaves, and the treatments of N3 P0, N3 P1, N1 P2, N2 P2 and N3 P2 were significantly higher than that of the control. After fertilization, starch and total NSC concentration of leaves were also higher than that of the control, and the treatments of N1 P1, N2 P1, N3 P1, N1 P2, N2 P2 and N3 P2 were significantly higher than those in the control. After fertilization, starch and total NSC concentrations of fine root gradually decreased with the increase of N application, but there was no significant difference from the control. With the increase of nitrogen addition, the leaf nitrogen concentration gradually increased, and N application also promoted the absorption of P, resulting the leaf P concentration of all fertilization treatments was higher than that of the control. N concentration of leaves was positively correlated with the net photosynthetic rate, chlorophyll, starch and total NSC concentration of leaves significantly, while P concentration of leaves was only positively correlated with the net photosynthetic rate and total NSC concentration of leaves significantly. Our results indicate that N and P fertilization could promoted the net photosynthetic rate by improving the N concentration in leaves, which resulted in the increase of NSC in leaves, but the allocation of NSC to fine roots decreased with the improvement of soil N supply. [ABSTRACT FROM AUTHOR]

:In order to study the growth of Iara; ~linii - Fraxinus rrwndshurica mixed forest, taking the Iara; ~linii - Fraxinus rrwndshurica mixed forest in Jiangshanjiao experimental forest farm of Heilongjiang Province as the research object, the soil physical and chemical properties and the biodiversity of understory vegetation were studied. The results showed that the mean values of growth indexes ( DBH, tree height and undershoot height) of low - density stands with retention density of 1 250 trees/hm2 were higher, which was more suitable for the growth of the Iara; ~linii - Fraxinu.s rrwndshurica mixed forest. The total soil porosity, capillary water holding capacity, non - capillary water holding capacity and saturated water holding capacity of 1 250 trees/hm2 stand were the highest, which indicated that the soil structure of the stand with this reserve density was better, and the soil permeability and water holding capacity were higher, the retention density of soil organic matter content was also the best, soil fertility was good. With the decrease of the reserve density, the richness, density, coverage, height and diversity index of understory vegetation increased. [ABSTRACT FROM AUTHOR]

Air pollution, mainly haze, has become one of the key factors threatening human health, survival and development. In order to improve the well - being of students and teachers, the research of the concentration of fine particles on various underlying surfaces, which means the surface of the earth in direct contact with the lower atmosphere on campus was delivered. According to this research, PM2. 5 concentration was measured in the dormitory area, activity area, forest farm, lawn, and family area of Northeast Forestry University. We analyzed the change of PM2. 5 concentration on these mentioned sites under sunny, cloudy, and partly cloudy conditions by collecting data. Taking a sunny day as example, the PM2. 5 concentration in the family area was about 15% higher than that in the lawn; and under different weather conditions, the PM2. 5 concentration in the activity area on a partly cloudy day was nearly 60% higher than that on a cloudy day. Results showed that the PM2. 5 concentration was higher in areas with frequent movement and human activities, while lower in areas covered by plants. The concentration of fine particles was higher on cloudy days and lower on partly cloudy and sunny days. Therefore, outdoor activities were not recommended on cloudy days. Also, a reasonable green space layout could effectively reduce the concentration of particulate matter and improve air quality. [ABSTRACT FROM AUTHOR]

To reveal the effects of different stand densities on soil respiration in young hybrid larch plantations, three 10-year-old hybrid larch plantations with different densities(1 283 plants per hectare, low density; 2 525 plants per hectare, medium density; 3 308 plants per hectare, high density) were established to measure soil respiration rate(from May to October) using LI-6400-09 infrared gas exchange analyzer in Northeast Forestry University Mao’er Mountain experiment forest farm, Shangzhi, Heilongjiang Province. Results showed that: soil respiration rate gradually decreased with the increase of stand densities, and the mean soil respiration rate(2.05μmol/(m2·s)) of high density stand was significantly lower than medium density stand(2.64μmol/(m2·s)) and low density stand(2.77μmol/(m2·s))(P<0.05). Soil temperature and moisture were both significantly positively correlated with soil respiration rate(P<0.05), but there were no significant differences between stands with different densities(P>0.05). Soil organic carbon and total nitrogen content were not significantly correlated with soil respiration rate(P>0.05). Soil microbial biomass carbon was significantly correlated with soil respiration rate(P<0.05), and had similar dynamic trends with soil respiration rate in May and July of peak growing season, with those in high density stand were both significantly lower than medium density and low density stand(P<0.05). The results indicate that soil microbial biomass is the main reason that causes the differences of soil respiration rate among hybrid larch stands with different densities, and building larch plantation with greater density will be beneficial to decrease C emission caused by soil respiration. [ABSTRACT FROM AUTHOR]

Taking the 43a Picea koraiensis plantation in Mengjiagang Forest Farm of Jiamusi of Heilongjiang Province as the re¬search object, tree growth and forest soil physical and chemical properties were measured. The differences of growth shape and soil fer¬tility artificial trees at different slope positions were analyzed to provide reference for the establishment of large - sized round wood culti- vation technology of P. koraiensis. The sample plots were set up at the upper, middle and lower slopes on the south slope of plantation to investigate the tree height, diameter in breast high of trees (DBH) , crown width and living branch height, and the soil samples from different soil layers were collected at five points to determine the soil pH and soil nutrient content (such as total carbon, total nitrogen, total phosphorus, total potassium, ammonium nitrogen, nitrate nitrogen, available phosphorus and available potassium). According to the survey, the trees growth on the downhill slope position was the best among different slope positions, and the tree height, DBH, crown width, living branch height and individual volume were the highest, respectively. Among the different slope positions, the com¬parison of tree height, crown width, living branch height and individual volume was ranked from small to large as uphill slope position, mid - slope position and downhill slope position. The comparison of breast diameter and individual volume were ranked from small to large as mid - slope position, uphill slope position, downhill slope position. The comparison of the unit area accumulation and the unit area of the chest height area was ranked from smaQ to larege as uphill slope position, downhill position and middle slope position. The results of soil physical and chemical properties analysis showed that the pH value increased with the decrease of slope positions. The soil nutrient content of the downhill slope position was the highest among different slope positions. In addition to the change trend of nutrient content of total potassium and available potassium was ranked from small to large as mid - slope position, uphill slope position and downhill slope position. The other nutrient contents were ranked from small to large as uphill slope position, mid - slope position and downhill slope position. Comparing the spatial distribution of soil nutrients on the same slopes, it was found that the soil nutrient content in the lower layer (0 -20 cm) was higher than that in the deeper ( >20 - 40 cm). The downhill slope position is more favorable for the txee growth of P. koraiensis and soil nutrient accumulation, which is suitable for the cultivation of P. koraiensis trees with large - sized round wood cultivation [ABSTRACT FROM AUTHOR]

Based on multi-sensor integration and spatial-temporal registration technology,this paper realizes the stereo parameter acquisition of forest trees. The self-developed forest parameter multi-sensor integrated system is used to collect the data of forest trees in the forest farm sample of Northeast Forestry University,and the spatial-temporal registration of point cloud data and image data is realized by the coordinate transformation relationship between sensors and the binocular vision algorithm. After the registration,the data extraction target coordinates are compared with the total station to obtain the real coordinates. The RMSE in the three directions of X,Y and Z are 0. 074,0. 117,0. 153 m,respectively,and the average RMSE is 0. 115 m. The results show that the data collected by the integrated system is valid and the registration effect is good. [ABSTRACT FROM AUTHOR]

In order to study the carbon sequestration of forests and its influencing factors such as tree species,mean DBH,average tree height,stems per hectare,altitude,slope and so on,this paper used two types of the forest resources permanent sample plot survey data from three typical forest farms in Muling City,Heilongjiang Province in 2012 and 2016. The carbon storage capacity of each forest farm was estimated by combining the biomass compatibility model and the carbon content of different tree species. Using ArcGIS’s ordinary Kriging interpolation method,spatial interpolation was used to obtain and analyze the spatial distribution pattern and dynamic changes of the two phases of carbon storage. The relationship between carbon storage and topographic factors such as elevation and slope,and forest stand factors such as tree height and DBH were analyzed,and a carbon storage estimation model was obtained. The results showed that the total carbon storage in the study area was on the rise,the forest carbon sink function was strengthening,the carbon storage in the central and western regions was significantly higher than those in other regions,and the carbon storage in the southeast was relatively low,the broad-leaved mingled forest,oak trees and artificial larch all played an important role in the carbon sink function of forest vegetation in this region. Conclusion: forest carbon sequestration was in good condition,and more attention should be paid to the protection and distribution balance of forest resources. [ABSTRACT FROM AUTHOR]

[Objective] As a new type of laser radar, Libackpack has the advantages that other laser radars do not have,but there is no corresponding literature reference. Therefore,this paper uses Libackpack to extract larch factor, which provides a theoretical basis for the use of Libackpack. [Method]Taking 9 plots of Larix Olgensis plantation sample land in Mengjiagang Forest Farm of Huanan County, eilongjiang Province as the research object, according to the morphological characteristics of trees, the point cloud data was acquired by using the Libackpack scanning plot, and the forest individual tree detection in the sample land and extraction of the diameter at breast height(DBH) and tree height were carried out by Lidar 360 software, then compared with the measured data for accuracy evaluation and correlation test. [Result](1) The matching rate of individual tree segmentation using Libackpack data was higher, with an average matching rate of 80. 20%.(2) The determination coefficient R2 of individual tree DBH extraction results was 0. 8 at the lowest and 0. 97 at the highest, the root means squared error(RMSE) was 1.92 m at the highest and 0. 6 m at the lowest,and the extraction precision of the diameter at breast height(DBH) was 97.62% at the highest and 92. 25% at the lowest.(3) The average extraction precision of single tree height was 80. 27%,and there was a great difference between the extraction results and the actual measurement. [Conclusion] The point cloud data scanned by Libackpack can be used for the individual tree detection in the sample land. The extraction result of DBH had the highest reliability,which can meet the requirements of collecting DBH data under forests. Due to sheltering, the incomplete scanning of the canopy top of individual tree point cloud data lead to the low extraction precision of the tree height relatively. It illustrated that Libackpack cannot be directly used for tree height data collection and extraction,and it was necessary to combine with other types of laser radar data for more precision analysis [ABSTRACT FROM AUTHOR]