To study the effects of different management modes on the growth and diversity of  larch plantation, and provided theoretical basis for the management of larch forest in north China. Taking the Larix principis-rupprechtii plantation in Longtoushan Seed Farm, Mulanweichang National Forestry Administration of Heibei Province as the research object, the sample plots were investigated by the method of combining random distribution and fixed sample plots，and the effects of N, T and CK management modes on the growth and diversity of L. principis-rupprechlii plantation were studied. The average annual growth of DBH and average annual growth of single tree volume in N model were higher than those in T model and CK model. After 2，4 and 6 years of operation，the average annual growth of DBH in N model was 1,1,1.2,1.9,1.3 and 1.9 times of that in T model and CK model,respectively. The average annual growth of single tree volume in N model was 1，1. 07,1.01，1.04, 1.03 and 1. 06 times of that in T model and CK model, respectively; With the increase of management time, the diameter class distribution was constantly changing. The number percentage of small diameter class plants in CK mode was higher, the number percentage of diameter class plants in N mode and T mode was higher, the DBH distribution of N mode and T mode stood shifts to the right relative to CK mode, and the number percent-age of diameter class plants in N mode stands of 16 cm and above was 30. 97% and 17. 24%higher than that of T mode and CK mode; With the increase of operation time, the number of shrub and grass species under N mode and N mode increased, while the number of shrub and grass species under CK mode decreased. After 2 years of operation, there was no significant difference bet ween the Shannon-Wiener index，Simpson index and Pielou evenness index N model and T model were higher than that of CK model ( P<0.05)，and the Shannon-Wiener index，Simpson index and Pielou evenness index of herb layer and shrub layer were significantly improved ( P<0. 05). N model promoted the growth and species diversity of L.principis-rupprechtii plantation; For larch plantation in north China, how to manage the forest depended on improving the growth of the stand in a long time scale, and also required long-term monitoring and research on the sample plots.

Abstract: In order to reveal Quercus mongolica population phenotype differentiation degree and variation law, and explore Q .mongolica characteristics of phenotype variation and geographical distribution pattern of traits. The differences and diversity of 10 phenotype characters of 6 natural populations of Q. mongolica from Hebei, Inner Mongolia, Liaoning, jilin and Heilongjiang provinces were studied. The phenotype differentiation and variation of Q. mongolica phenotype traits with methods of nested analysis of variance, correlation analysis and cluster analysis were analyzed. The results showed that 9 phenotype traits were significantly different. The phenotype differentiation coefficient was 48. 12%，and the degree of phenotype differentiation within populations was slightly higher than that between populations. The Shannon index of 10 phenotype characters was all greater than 1. 00，indicating that the characters were abundant, and the coefficient of variation of population varied greatly, ranging from 5. 0%-51.1%. The variation of the same phenotype trait between different populations and the variation of different phenotype traits within the same population were different. The population of Q. mongolica was divided into three groups by cluster analysis.the clustering results were inconsistent with geographical distance.

The main chemical components of different organs of larch (trunk sapwood, branches, bark, leaves and pine cone) were studied, and their pyrolysis characteristics and basic physical and chemical properties of biochar were analyzed, which provided theoretical basis for multi-stage and high-value utilization of larch felling residues，carbonization back to forest and soil improvement. The contents of cellulose, hemicellulose, lignin, benzene alcohol extract and ash in each organ of larch were isolated and determined, and the thermal stability of each organ material was characterized. Different organ materials of larch were carbonized at 500，700 and 900 C，respectively, and the physico-chemical properties of biochar were characterized. The sapwood of larch trunk had the highest content of hygrocellulose, the lignin and ash content of pine needles had the highest content, and the benzene alcohol extract content of branches had the highest content. The pyrolysis process of larch was divided into three stages: drying,rapid thermal degradation and calcination. The main pyrolysis reaction occurred at 200 一 400 C. The results of gravimetric analysis and carbon yield analysis showed that pine needles had the highest carbon residue rate. The biochar yield and surface functional groups of the same tissue and organ decreased with the increase of carbonization temperature.' The pH value of biochar in the same tissue and organ increased gradually with the increase of carbonization temperature. The specific surface area of the five biochar was bark charcoal > trunk charcoal > pine cone charcoal > pine needle charcoal > branch charcoal, The cellulose content of larch sapwood was the highest, which was suitable for paper-making and other raw materials. The lignin content of pine needles was high，which was suitable for extracting chemicals. Tree trunks sapwood, bark and branches were suitable for carbonization. Bark carbon had higher carbon yield, larger specific surface area, strong alkaline pH and stable chemical properties, which could be used to improve acidic soil.

In order to study vessel cell structure and its change trend in the different ages 107( Populus × euramericana cv.“74/76") of the secondary xylem early wood and late wood timber, and it was the anatomical characteristics of secondary xylem in different tree ages 107 poplar that measured by microscopic imaging technology for slice specimen，and the experimental data was analyzed by variance analysis. In this study, the radial changes of vessel cells in early wood and late wood of 107 poplar at different ages of 3 (3 a)，5 (5 a), 7 (7 a) and 10 (10 a) in a forest farm in Mancheng District of Baoding City were studied. The results showed that: (1) The width value of annual rings was increased rapidly from the pith to the 3rd year, and then showed the trend of reduction with a rapid growth period during 3 to 7 years for 107 poplar trees; The late wood percentage was gradually increased from pith to the phloem, and the value of variation range was 4. 67%- 8.70% and the rate of late wood was low. (2) It gradually increased with the increasing age of the growth ring that the tangential and radial diameter of vessel cells in the 3 years, 5 years, 7 years early wood and late wood, but that in 10 years showed an increasing trend first and then a decreasing trend. It gradually increased with the increase of the growth wheel age that the thickness of the double wall of the vessel, pore chain radial diameter and pore chain tangential diameter in the early wood and late wood of different ages. The wall-cavity ratio gradually decreased with the increase of the growth ring age, and the value of variation range was 0. 12 - 0.18 and 0.16 - 0.25，respectively. It showed that slight upward trend with the increase of growth ring age for the vessel cells ratio in early wood of 3 years polar trees, and a trend of reduction for ones in late wood, and a trend of reduction with the increasing age of growth ring for the vessels ratio in early wood and late wood of 5 years, 7 years and 10 years, its value of variation range was 15. 21%-19. 87% and 13. 96%-17. 17%，respectively. (3) It significantly indicated that the differences in the radial changes of the anatomical structure of 107 poplar in different age groups. According to the differential characteristics and data, which was combined with the requirements of the micro-anatomical structure index of wood, it could be used as the basis for judging the orientation cultivation cycle and cutting time of 107 poplar. In conclusion, if the aim was to cultivate large diameter timber forest, the best rotation period was 10 years old. However, if the aim was to cultivate medium and small timber forests, the best rotation period was at 7 years of age in the young forest stage for the poplar of the artificial forest.

The economic forest planting area in Taihang Mountain Area was taken as the research object. Based on the hyperspectral remote sensing data of unmanned aerial vehicle, the hyperspectral characteristic database of different economic forest species was constructed, and the optimal identification model of economic forest species by hyperspectral remote sensing was obtained by using CART decision tree, maximum likelihood classifier (MLC), random forest (RF) and support vector machine (SVM). The results showed that: (1) The water vapor absorption bands of apple, apricot, persimmon, cherry and walnut were obviously different around the reflection peak of 550 nm, between 750-950 nm and around 960 nm; (2) The simple ratio index (SR), carotenoid reflex index 2 (CRI2), green band index (GRVI) and other 7 plants were more than 0.05, which were beneficial to the identification of economic forest species; (3) SVM was the best classification method based on spectral characteristic band, vegetation index and texture feature, which was better than MLC and RF algorithm. The overall accuracy (OA) was 95.11% and Kappa coefficient was 0.915 8. To sum up, based on the combination of characteristic band, vegetation index and texture features, the identification method of support vector machine (SVM) classification was the best identification method for six tree species.

In order to investigate the effects of different thinning types on the spatial structure of ecological forest in Beijing Plain, nine permanent plots were established in Tongzhou District, Beijing, including representative forest types such as Salix matsudana, Styphnolobium japonicum and Fraxinus chinensis. After selecting the target trees, each stand type was cut with interference, group and strip thinning respectively. The spatial structure of plain ecological forest and the effect of thinning on the spatial structure of target tree and stand were analyzed by using the optimized spatial ratio, angular scale and density.The Comprehensive Spatial Structure Index (CSSI) was constructed to evaluate the effects of different thinning methods on the spatial structure of ecological forest in Beijing Plain. The results indicated that: (1) CSSI combined angular scale, density, and optimized size ratios, which was suitable for the spatial structure evaluation of ecological forests in Beijing Plain. (2)The spatial distribution pattern of plain ecological forests represented by S. japonicum, F. chinensis and S. matsudana was evenly distributed before thinning, most of the trees in a moderate state. The forests were relatively dense, and the spatial structure of F. chinensis and S. matsudana was better than that of S. japonicum. (3) Thinning could significantly optimize the spatial structure of plain ecological plantation, especially for forests with high density such as S. japonicum. (4) For different tree species, the optimal thinning methods to improve the spatial structure were different, but for the spatial structure unit of target tree, the optimal degree of interference tree thinning was the most obvious.

Cultivated land was an important cornerstone of national survival and development, the foundation for promoting agricultural production and ensuring food security, and the important guarantee for maintaining national economic security and social stability. Cultivated land resources were the basis of agricultural production, and agricultural development was inseparated from the sustainable utilization of cultivated land. In order to ensure food security and promote the sustainable development of social economy, this paper took Hejian City as the research area, adopted the land use dynamic attitude and other methods to study the cultivated land in Hejian City, selected evaluation indicators, constructed a sustainable use evaluation system for cultivated land, and used multi-factor weighted summation to conduct district research on Hejian cultivated land. The results showed that: (1) From 2010 to 2019, the cultivated land area decreased by 12 713.71 hm², and the cultivated land occupied more; From 2016 to 2019, irrigated land decreased significantly, the area decreased to 10 318.99 hm². From 2010 to 2019, the total area of dryland decreased by 3 920.76 hm². Overall, the area of arable land decreased sharply. (2) To evaluate and analyze the sustainable utilization of cultivated land resources in Hejian City, the cultivated land was divided into four levels, and the results of the zoning were divided into sustainable area, general sustainable area, preliminary sustainable area and weak sustainable area. (3) Put forward corresponding countermeasures for each zone to promote the improvement of cultivated land quality.

To reveal the differences in photosynthetic characteristics of three Hippophae rhamnoides strains, and explore the effects of mature leaf morphology and other factors on their net photosynthetic rate, this study measured the leaf morphology index and photosynthetic physiological indicators of three H.rhamnoides strains, namely "Nordic No.1", "Yulu", and "Shenqiuhong", and analyzed the influencing factors of net photosynthetic rate. The results showed that:(1) "Yulu" had the largest leaf area and "Shenqiuhong" had the smallest leaf area, but the differences in leaf morphology and various indicators among the three varieties were not significant; (2) Netphotosynthetic rate(Pn),transpiration rate(Tr),intercellular carbon dioxide concentration(Ci),and stomatal conductance(Gs) of "Nordic No.1" were significantly higher than the other two varieties, and the water use efficiency and stomatal limitation values were significantly lower than the other two varieties; (3) Multiple stepwise regression analysis showed that physiological factors transpiration rate and intercellular carbon dioxide con centration were the main influencing factors of netphotosynthetic rate in the three varieties. The decrease in netphotosynthetic rate in "Nordic No.1" and "Shenqiuhong" was influenced by stomatal conductance, while the decrease in netphotosynthetic rate in "Yulu" was caused by non stomatal limitation. In summary, "Nordic No.1" maintains a higher photosynthetic production capacity by consuming more water; "Shenqiuhong" maintained photosynthetic production capacity through higher water use efficiency. However, there was no significant difference in photosynthetic rate and other indicators between "Yulu" and "Shenqiuhong", and the photosynthetic capacity was similar, indicating that "Yulu" guaranteed its photosynthetic production capacity through a larger leaf area.