To address the challenge of Sentinel-2 data in distinguishing spectrally similar tree species， this study established a multi-dimensional feature fusion classification system based on the google earth engine （GEE） cloud platform， with Tieling City， Liaoning Province as the experimental area. By integrating Sentinel-2 multi-temporal data and employing multi-dimensional feature statistical methods， we extracted spectral and vegetation index features including quantiles， extremes， and standard deviations， combined with topographic， textural， phenological， and harmonic features， forming a total of 120 features across six categories. Multiple feature combination schemes were designed and implemented through a hierarchical classification strategy using the random forest algorithm， ultimately achieving fine classification of seven dominant tree species： Pinus tabuliformis， Pinus sylvestris var. mongolica， Larix gmelinii， Populus， fruit trees， Quercus mongolica， and Robinia pseudoacacia. The results demonstrated that multi-dimensional temporal statistical features effectively captured subtle interspecies differences. Variations in water content between Pinus sylvestris var. mongolica and Pinus tabuliformis were successfully characterized through multiple vegetation indices. Topographic and textural features played decisive roles in distinguishing deciduous species. The classification overall accuracy reached 94.7% for evergreen species and 88.1% for deciduous species， with all six feature combination schemes achieving overall accuracy exceeding 77.9%. This study confirms that the integration of multi-dimensional feature statistical methods with the GEE platform fully exploits the multi-band advantages of Sentinel-2 data， significantly enhancing large-scale tree species classification capabilities through temporal feature analysis. It provides a cost-effective solution for dynamic monitoring of forest resources at large-scale， with the cloud-based processing framework demonstrating potential for application expansion to broader geographical regions.
Land is an indispensable part of human life. The analysis of land use status is helpful to deeply understand the relationship between environmental conditions and economic development， and to achieve a more reasonable land use model. Predicting future land use will help improve the sustainable management of land resources and provide a scientific basis for assessing carbon potential. Taking Heilongjiang Province as the research area， the current situation of land use in Heilongjiang Province from 2000 to 2020 was analyzed， and the patch-generating land use simulation （PLUS） model coupled with the long short-term memory （LSTM） model was adopted to simulate and predict the land use situation in Heilongjiang Province in 2030. The results showed that： 1） The Kappa coefficient for verifying the PLUS-LSTM model was 0.878. The relative simulation errors of the six land types （cultivated land， forest land， grassland， water area， construction land， and unused land） were all less than 15%. Compared with the traditional model， it had higher accuracy and can be used to simulate the land use situation in Heilongjiang Province in 2030. 2） Compared with 2020， the area of forest land， grassland， water area， and construction land in Heilongjiang Province would increase in 2030. Among them， the change rate of construction land was the highest， 8.57%； the area of forest land increased by 2 584.26 km²， mainly in the central region； the expansion of grassland was mainly in the southwest. The area of cultivated land and unused land decreased， and the unused land changed the most， with a change rate of 29.68%.
Used 15-year-old Pinus koraiensis on three slope aspects （sunny slope， semi-sunny slope， and shady slope） in Wangjiagou Management Area， Maoshan Experimental Forest Farm of Northeast Forestry University， as materials to investigate the responses of the functional traits and photosynthetic characteristics of Pinus koraiensis needles to the differences in environmental factors on different slope aspects. The results showed that the soil moisture content of the shady slope was 5% higher than that of the sunny slope， and the photosynthetically active radiation of the sunny slope was 3 times that of the semi-sunny slope and 10 times that of the shady slope. The specific leaf area of Pinus koraiensis needles on shady slopes was about 1.29 times that of sunny slopes. Pinus koraiensis growing on the shady slope obtained more light energy by expanding the specific leaf area. The stomatal density， water content and NSC content of the coniferous leaves on the sunny slope were significantly higher than those on the semi-sunny slope and the shady slope. The photosynthetic capacity of the one-year coniferous leaves was higher than that of the two-year coniferous leaves， and the photosynthetic characteristics on the sunny slope were higher than those on the semi-sunny slope and the shady slope. The environmental conditions on the sunny slope were more conducive to the growth and development of Pinus koraiensis. The main environmental factors affecting the photosynthetic characteristics of Pinus koraiensis needles were land surface temperature and photosynthetically active radiation， and the main environmental factors affecting the functional traits of Pinus koraiensis needles were photosynthetically active radiation. Pinus koraiensis of different slopes adapted to environmental changes by adjusting their own needle morphology， photosynthetic characteristics and nutrient distribution to form a unique adaptation strategy. The environmental factors that affect the growth and development of Pinus koraiensis trees are not single， but the result of the coupling of multiple environmental factors.
To investigate the effects of nitrogen and phosphorus additions and water treatments on the growth and photosynthetic characteristics of Fraxinus mandshurica seedlings， this study used one-year-old seedlings of F. mandshurica as the research subject. A randomized block design was utilized with three water gradients： drought （DR， volumetric water content 13%）， control （CK， volumetric water content 26%）， and water addition （W， volumetric water content 39%）， and four fertilization gradients： N0P0 （0 g/plant N， 0 g/plant P）， N1P1 （0.5 g/plant N， 0.25 g/plant P）， N2P2 （1 g/plant N， 0.5 g/plant P）， and N3P3 （1.5 g/plant N， 0.75 g/plant P）. The growth， biomass allocation， and photosynthetic characteristics of F. mandshurica seedlings under different water and fertilizer treatments were analyzed to elucidate their physiological responses to these conditions. The results showed that water availability had a more significant impact on the growth of F. mandshurica seedlings compared to nitrogen and phosphorus fertilization. When soil water content was 39% and fertilization reached N2P2， the seedling height growth， base diameter growth， total biomass， and net photosynthetic rate achieved their maximum values. Specifically， these parameters were 82.59%， 39.83%， 74.61%， and 64.03% higher， respectively， compared to the control （soil water content 26%+N0P0）. Compared with water addition treament， drought significantly reduced indicators such as seedling height growth， base diameter growth， total biomass， and net photosynthetic rate of F. mandshurica seedlings. Therefore， appropriate fertilization can enhance the growth of F. mandshurica seedlings under adequate water conditions. These findings provide a theoretical basis for the cultivation of F. mandshurica seedlings.
Exploring the effects of different rejuvenating treatment measures on the nutritional composition， secondary metabolites and photosynthetic characteristics of Populus simonii×P. nigra leaves， and providing a theoretical basis for the establishment of the rejuvenating system of P. simonii×P. nigra in forestry practice in the future. The 40-year-old superior clones of P. simonii×P. nigra were rejuvenated and cut into seedlings （the mother tree cutting seedlings were used as the control group） by two methods of buried stems and buried roots. The differences in water content， total flavonoid content， and light saturation point among the three cutting seedlings were measured and analyzed. The results showed that the rejuvenating treatment could significantly increase the water content and nutrient element mass fraction of P. simonii×P. nigra leaves. Among them， the relative water content （81.600%） and total potassium mass fraction （2.332%） of the leaves of the buried stem cutting seedlings were the highest. The contents of secondary metabolites such as total phenolics （1.633%） and total flavonoids （6.214%） in the leaves of buried root cutting seedlings were significantly higher than those in the other two leaves. The light saturation point （1 585.093， 1 730.273 μmol/（m2·s）） and CO2 saturation point （1 132.690、1 123.560 μmol/mol） of the leaves of the buried root and stem cutting seedlings were higher than those of the mother tree， which improved the photosynthetic capacity of P. simonii×P. nigra to a certain extent. It can be seen that rejuvenating treatment will have a positive impact on the nutritional composition and photosynthetic characteristics of P. simonii×P. nigra leaves.
The water adaptation strategy of extremely small population Taxus cuspidata is the basis of its response to climate change， and studies based on isotopes are still blank. By measuring the δD and δ18O values of plant xylowater and soil water， direct correlation method and multiple linear mixing model （Iso-Source） were used to analyze the water sources and water use strategies of Taxus cuspidata. The results showed that： the fluctuation range of soil water content in 0-40 cm soil layer of Taxus cuspidata was 32.69% to 54.29%， and the trend was first increased and then decreased； the fluctuation range of soil water content in 40-100 cm soil layer was 22.55% to 25.73%， and the fluctuation range was small. The soil water content in the 0-40 cm soil layer was higher than that in the 40-100 cm soil layer. The δD and δ18O values of soil water from 0 to 100 cm of Taxus cuspidata were -84.26‰ to -52.17‰ and -11.69‰ to -7.49‰， respectively， and decreased gradually with the increase of soil depth. The δD and δ18O values of soil water changed sharply in 0-40 cm soil layer， but changed little in 40-100 cm soil layer. The main water source of Taxus cuspidata was 0-40 cm soil water， and the utilization rate was 89.55%， and the utilization rate of 40-70 cm and 70- 100 cm soil water was 5.15% and 5.30%， respectively. This study reflects the water adaptation of Taxus cuspidata under the background of global warming， and the results can provide scientific basis for assessing the stability of Taxus cuspidata ecosystem under future climate change.
The climate in Northeast China is cold， and low-temperature events can severely affect the growth of trees. Fraxinus mandshurica is a precious timber tree species in Northeast China. Little was known about its fiber anatomical characteristics in responses to low temperatures and its adaptation strategies. The progeny test forest of Fraxinus mandshurica in Xiao Xing'an Mountains was selected as research object. Dendrochronology and wood anatomy methods were used to investigate the relationship between the fiber anatomical characteristics of Fraxinus mandshurica and the key climate factors， aiming to clarify the effect of low temperatures on wood fiber anatomical characteristics. The results showed that the fiber anatomical characteristics of Fraxinus mandshurica in Xiaoxing'an Mountains exhibited significant interannual variability. There was a highly significant positive correlation between the fiber cell number （FN）， the total fiber cell area （TFA） and the ring width （RW）. All of them showed a trend of ‘first increase and then decrease’ during the young forest stage. The fiber density （FD） and square of the total-to-bound ratio （（T/B）2） showed a decreasing trend year by year. The mean fiber cell area （MFA） and the overall mean thickness of all fiber cell walls （CWTall） showed an increasing trend annually. The fiber anatomical characteristics of Fraxinus mandshurica were greatly affected by temperature， especially the minimum temperature during the growing season. Low-temperature events suppressed the radial growth of Fraxinus mandshurica. The ring width， the fiber cell number， the mean fiber cells area， the total fiber cell area， and the mean percentage of fiber cell area within xylem （RFTA） were significantly decreased by 32.6%， 20.3%， 22.4%， 45.9% and 9.4%， respectively， compared with non low-temperature years， while the fiber density increased by 11.6%. In response to low-temperature events， Fraxinus mandshurica adopted a relatively conservative survival strategy of reducing the fiber cell number and increasing the fiber density. In response to low-temperature events， Fraxinus mandshurica adopts a relatively conservative survival strategy by reducing the number of wood fiber cells and increasing fiber cell density. These findings provide a scientific basis for the breeding of cold-resistant Fraxinus mandshurica in the Xiao Xing'an Mountains region.
Larch is an important plantation tree species in northern China. In order to reveal the physiological effects of tree management on the mother tree of larch， the mother tree of the second generation seed orchard of larch was used as the research object in this study. The physiological indexes such as endogenous hormones， nutrients， oxidase， MDA and free proline in the fruiting branches of the mother tree of larch were determined and analyzed by means of trunk truncation， pulling branches and trunk truncation+pulling branches. The results showed that the contents of IAA， GA3 and ZT were increased， while the content of ABA was decreased. Especially for the treatment combining trunk truncation + pulling branches （TT+PB）， the contents of IAA， GA3 and ZT in TT+PB were 107.80%， 108.61% and 107.29% of CK， respectively. In terms of endogenous hormone ratio， tree management increased the ratio of IAA/ABA， GA3/ABA， ZT/ABA， GA3/IAA， ZT/IAA and ZT/GA3. Tree management increased the contents of soluble protein， starch and soluble sugar in the fruiting branches of larch mother tree， especially trunk truncation + pulling branches （TT+PB）， whose contents of soluble protein， starch and soluble sugar were 103.09%， 115.99% and 104.40% of CK. The activity of SOD and POD was improved by tree management， and the resistance of larch mother tree was improved. In summary， tree management technology provides sufficient material substrate for improving seed yield and quality of larch mother tree. This study provided theoretical support for high and stable yield of larch seed orchard.
To conduct a preliminary evaluation and select superior clonal lines of Larix olgensis， this study used 68 clonal lines from the Larix olgensis collection area at the Qingshan National Larch Seed Orchard in Linkou County， Mudanjiang City， Heilongjiang Province， as materials， measured their growth and wood quality traits were measured， and analyzed them using variation analysis， variance analysis， correlation analysis， and other methods for comprehensive evaluation. The results of the variance analysis showed that the differences in growth and wood quality traits among the clonal lines were highly significant. The variation analysis of growth and wood quality traits indicated that the coefficients of variation ranged from 2.55% to 19.71%， with volume exhibiting the largest coefficient of variation and total cellulose having the smallest. The repeatability values ranged from 0.602 to 0.924， with tree height showing the highest repeatability， followed by basic density and total cellulose. Correlation analysis revealed that diameter at breast height （DBH） was significantly positively correlated with tree height， and the east-west crown width was highly positively correlated with the north-south crown width. Volume， DBH， and tree height all exhibited significant positive correlations， with a stronger correlation between volume and DBH， indicating that volume was more influenced by DBH. Furthermore， correlation analysis revealed no significant relationship between growth traits and wood quality traits. Using the Breeding multi-trait evaluation method， superior clonal lines were selected based on both growth and wood quality traits， with a selection rate of 15%. The superior clonal lines selected for growth traits were 241， 456， 96， 475， 179， 161， 83， 759， 339， and 43， while those selected for wood quality traits were 357， 223， 161， 7， 249， 741， 657， 14， 475， and 113. The clonal lines 475 and 161 exhibited excellent performance in both growth and wood quality traits. The selected superior clonal lines can provide valuable material for the future breeding of superior varieties.
Studies on plantations of Juglans mandshurica in northeast China have primarily focused on growth traits， while relatively limited research on seed and fruit variation. Therefore， early selection of Juglans mandshurica based on integrated growth and seed traits can accelerate its genetic improvement programs. Taking 10 years old Juglans mandshurica experimental forest as the research object， this study measured the descriptive phenotypic traits， growth traits， and seed traits. Variance analysis， principal component analysis and Breitzin comprehensive evaluation were used to analyze the variation of traits among different families of Juglans mandshurica. The results showed that the variation coefficient of descriptive phenotypic traits ranged from 16.15% to 57.70%， the variation coefficient of ridge width （57.70%） and ridge protrusion （56.98%） were the largest， and the variation coefficient of top prominence （16.15%） was the smallest， the phenotypic traits were relatively stable. Except for the branch angle， the other quantitative traits were significantly different among families （P<0.01）. Among the growth traits， the variation coefficient of volume （58.06%） was the largest， and other related indicators ranged from 17.03% to 22.51%. Among the fruit traits， the variation coefficient of single fruit mass （17.12%） was the largest， and other related indexes ranged from 5.13% to 8.19%. The variation coefficient of single nut mass （18.76%） was the largest， and other related indexes ranged from 6.74% to 9.25%. Correlation analysis showed that there were significant positive correlations among plant height， crown diameter， basal diameter， DBH and volume （P<0.01）， there were significant positive correlations among fruit tridiameter， nut tridiameter， single fruit mass and single nut mass （P<0.01）. General combining ability analysis showed that three excellent parents were selected for each trait. Four principal components were extracted by principal component analysis， and the cumulative contribution rate reached 84.32%. By using the comprehensive evaluation method of multiple traits， five excellent families were selected from the perspectives of wood use， fruit use， and both fruit and wood use. The excellent families preliminarily selected could provide theoretical support for the selection and application of Juglans mandshurica in this area.
To identify superior poplar varieties adapted to different soil moisture conditions， this study evaluated nine major cultivated poplar varieties in Heilongjiang Province—namely， Populus cathayana （JDQY）， Populus deltiodes×P.cathayana ZHF2， （Populus×euramericana）×（P.simonii×P.nigra）（2111）， Populus euramericana ‘N3016’×P.ussuriensis ‘HQ-1’ （HQY）， P.alba L×P.berolinensis Dippel （YZY）， 1019， Populus ‘Heifang-3’ （QSY）， 406， and Populus deltoides×Populus simonii ‘LongFeng-2’ （LF2）. By applying two soil moisture gradients （mild drought， HL is 14%- 18%； moderate drought， HM is 6%-10%）， we systematically measured 14 morphological and physiological-biochemical indicators， including apparent morphology， leaf water content， relative chlorophyll content， ion metabolism， and antioxidant enzyme activities. Based on principal component analysis and membership function evaluation， the drought resistance rankings were as follows： （1） under mild drought， JDQY， HQY， QSY， YZY， LF2， 2111， 406， ZHF2， 1019； （2） under moderate drought， JDQY， HQY， 2111， YZY， LF2， QSY， ZHF2， 406， 1019. Research indicated that， JDQY maintained osmotic balance by by significantly accumulating K⁺ and Ca²⁺， while HQY responded rapidly to oxidative stress via elevated superoxide dismutase （SOD） activity， both exhibited broad-spectrum drought resistance under two types of stress. This study reveals inter-varietal differences in drought resistance and underlying physiological mechanisms among the nine poplar varieties， identifying JDQY and HQY as drought-tolerant candidates. The findings provide a theoretical basis for stress-resilient afforestation and precision tree species selection in cold， drought-prone regions.
Acanthopanax senticosus is a valuable medicinal and edible plant， with significant potential for leaf utilization. To comprehensively investigate the phenotypic diversity of A. senticosus in Heilongjiang Province， 281 natural individuals from the 10 provenances were transplanted into a common nursery garden under uniform cultivation. Two relative phenotypic traits and nine phenotypic traits were measured and calculated， followed by variation， variance， correlation， and cluster analyses. Key findings include： （1） Significant differences （P<0.01） were observed in 11 leaf phenotypic traits both among and within populations， with inter-population variation exceeding intra-population variation. Traits such as petiole hair density （PH）， prickles on petiole （PP）， prickle on petiole length （PPL）， leaf vein hair density （LVH）， prickle vein density （PV）， and prickle on leaf vein length （PVL） exhibited extremely high coefficients of variation （CV）， indicating substantial variability. （2） The average diversity index of A. senticosus reached 1.615， with four phenotypic traits exceeding 1.9. Eight traits showed repeatability above 0.7， reflecting rich leaf phenotypic diversity and relatively stable genetic inheritance of A. senticosus. （3） Leaf phenotypic traits were strongly correlated， among which the prickle-related characteristics of petioles and veins were interrelated and vary together. Leaf phenotypic traits also correlated with geographic and climatic factors， with longitude identified as the primary environmental driver. （4） Cluster analysis classified the 10 provenances into three distinct groups with varying proportions， highlighting population-specific divergence. This study establishes a foundation for elucidating the genetic mechanisms of leaf traits， informs conservation strategies， germplasm collection， and breeding programs for A. senticosus， and provides a theoretical framework for developing reliable phenotypic identification methods.
Soil nitrogen （N） and phosphorus （P） are critical for tree growth. Investigating the variation characteristics of N and P fractions across soil profiles and their primary influencing factors following the transformation from pure plantations to multi-layered， uneven-aged plantations provides insights into the mechanisms by which structural regulation of pure forest stands impacts soil quality. This study focused on pure Cunninghamia lanceolata plantations and multi-layered uneven-aged mixed C. lanceolata and Phoebe bournei plantations （hereafter referred to as mixed C. lanceolata and P. bournei plantations）. We examined the variations in N and P fractions， other soil properties， and root traits across different soil layers （0-10 cm， >10-30 cm， >30-50 cm） in these two stands， as well as their interrelationships. The results revealed that after the transition from pure C. lanceolata plantations to mixed C. lanceolata and P. bournei plantations， the contents of most N and P fractions in the 0-10 cm soil layer significantly increased. Specifically， labile， moderately labile， and stable P fractions， along with total P contents， increased by 38.2%， 31.6%， 15.4%， and 25.1%， respectively， compared to the pure C. lanceolata plantations， and inorganic， organic， and total N contents increased by 42.1%， 35.8%， and 35.9%， respectively. In the >10-30 cm soil layer， the contents of moderately labile organic P， inorganic N， acid-hydrolysable organic N， total N， and total P were significantly higher in the mixed C. lanceolata and P. bournei plantations than pure C. lanceolata plantations. However， no significant differences in N and P fractions contents were observed between the two stands in the >30-50 cm soil layer. The contents of N and P fractions of the two stands decreased with increasing soil depth. Furthermore， the transformation of stand structure affects root distribution and traits. The mixed C. lanceolata and P. bournei plantations exhibited higher root biomass， root length density， and specific root length compared to pure C. lanceolata plantations. The root biomass and root length density at 0-10 cm increased by 124.66% and 269.23%， respectively， compared to the pure C. lanceolata plantations. In pure C. lanceolata plantations， root biomass and root length density initially increased and then decreased with soil depth. In contrast， due to the surface aggregation of P. bournei roots in the mixed C. lanceolata and P. bournei plantation， the root biomass and root length density of C. lanceolata gradually increased with soil depth. The variations in soil nitrogen and phosphorus components across different stand types and soil depths were primarily associated with root distribution， soil organic carbon， and soil microbial characteristics. The findings highlight that structural optimization of C. lanceolata plantations in subtropical regions significantly influences soil fertility.
The construction and quality improvement of water conservation forests are important research contents in forest management. This paper compares the differences in water conservation functions among four forest types in the eastern mountainous areas of Heilongjiang Province through the study of litter and soil hydrological effects： Korean pine-broadleaved forest （KH）， spruce-fir forest （YLS）， larch forest （LYS）， and Mongolian oak forest （MGL）. The results indicate that the total thickness of the litter layer for the four forest types in the mountainous areas of eastern Heilongjiang Province varies from 3.08 to 7.78 cm， and the litter stock volume ranges from 7.65 to 11.08 t/hm². The effective water retention capacity of the undecomposed litter layer is 2.58-15.41 t/hm²， with an effective retention rate of 56.02%-216.67%. The effective water retention capacity of the semi-decomposed layer is 0.95-9.88 t/hm²， and the effective retention rate reaches 62.78%-281.29%. The water conservation capacity of the undecomposed layer is higher. The immersion time of the litter has a logarithmic relationship with the litter's water holding capacity and a power function relationship with the water absorption rate. For the four forest types， the soil bulk density increases with the increase of soil depth， while the soil porosity decreases. The soil saturated water holding capacity in the 0-20 cm soil layer of KH， YLS， LYS， and MGL ranges from 973.41 to 1，085.08 t/hm². The total water holding capacity of the four forest types， from largest to smallest is KH， LYS， MGL， and YLS. The soil layer plays a key role in the water conservation function of forests， with a water holding capacity of 97.41%-98.15% of the total water holding capacity. The research results provide a theoretical basis for the quality improvement and transformation of water conservation forests in this region.
In order to study the relationship between the growth and development of native plants and the accumulated temperature of the environment under the compound heavy metals stress， a pot experiment was conducted to analyze the response of the leaf expansion process of six plants to the active accumulated temperature （A AT） and daily temperature difference accumulated temperature （D AT） under the stress of seven mixed heavy metals by setting three concentration gradients. A Logistic growth curve with accumulated temperature as the independent variable was established. The results showed that the leaf area constants of six plants under different concentrations of heavy metals stress were significantly different from those of the control group. There were significant differences between the leaf area growth of the six plants in the control group and the leaf area growth of the plants under different concentrations of heavy metal stress. The relative leaf area of the six plants in the control group， A AT and D AT were in accordance with the Logistic growth curve， but the overall fitting degree （R 2） of theese model in the heavy metals stress groups was poor and the prediction accuracy was low. In particular， the R 2 of the relative leaf area-A AT fitting model of the low concentration treatment was only 0.265 4 for Ficus tikoua， indicating that the heavy metal stress significantly interfered with the normal growth process of the plant. The leaf area-accumulated temperature Logistic growth model can better reflect the growth difference of leaf area under environmental stress during the leaf expansion period of plants. The research results can provide scientific reference for the screening and cultivation of ecological restoration seedlings in mining areas.
To investigate the density response characteristics and driving mechanisms of plant diversity and biomass in typical forest stands of the Loess Plateau， this study focused on Robinia pseudoacacia and Pinus tabuliformis plantations， establishing five density gradients for each （The density gradient Ⅰ of Robinia pseudoacacia forests was 1 200-1 500 stems/hm²， density gradient Ⅱ was 1 500-1 800 stems/hm²， density gradient Ⅲ was 1 800-2 100 stems/hm²， density gradient Ⅳ was 2 100-2 400 stems/hm²， and density gradient Ⅴ was 2 400-2 700 stems/hm². The density gradient I of Pinus tabuliformis forests was 1 000-1 500 stems/hm²， density gradient Ⅱ was 1 500-2 000 stems/hm²， density gradient Ⅲ was 2 000-2 500 stems/hm²， density gradient Ⅳ was 2 500-3 000 stems/hm²， and density gradient Ⅴ was 3 000- 3 500 stems/hm²）. Through field surveys， diversity index calculations， and biomass measurements， we employed one-way ANOVA， two-way ANOVA， and Pearson correlation analysis to identify influencing factors. The results showed， （1） Forest type significantly affected plant diversity and biomass， with shrub diversity and tree biomass significantly higher in Pinus tabuliformis stands， while herbaceous diversity was greater in Robinia pseudoacacia stands. （2） In Robinia pseudoacacia stands， shrub and herb diversity indices exhibited bimodal curves with density， peaking at 1 500- 1 800 stems/hm²， whereas in Pinus tabuliformis stands， shrub diversity peaked at 1 500-2 000 stems/hm²， and herb diversity was significantly higher at low densities （1 000-1 500 stems/hm²）. Aboveground and total biomass of Robinia pseudoacacia reached maxima at 1 800-2 100 stems/hm²， while Pinus tabuliformis biomass showed weaker density dependence. （3） Correlation analysis revealed that shrub diversity indices in Robinia pseudoacacia stands were negatively correlated with tree height， and herb evenness indices were negatively correlated with slope. For Pinus tabuliformis stands， diversity indices of shrubs and herbs were significantly correlated with crown width， and positively correlated with diameter at breast height （DBH） and tree height. （4） Pinus tabuliformis demonstrated greater competitive advantages in Loess Plateau ecological restoration. Moderate densities （Robinia pseudoacacia： 1 800-2 100 stems/hm²； Pinus tabuliformis： 1 500-2 000 stems/hm²） synergistically enhanced plant diversity and biomass， with DBH， crown width， and topographic factors identified as key regulators. These findings provide a scientific basis for optimizing stand density and improving ecological functions in the Grain for Green Project on the Loess Plateau.
By comparing the response of root and overall seedling growth of Fraxinus mandshurica （deep-rooted seedlings） and Larix gmelinii （shallow-rooted seedlings） to root space requirements and root restrictions， and this turns to clarify the relationship between the root type， root development and root growth space of seedlings. This study took the current-year F. mandshurica and L. gmelinii container seedlings as the research objects， and set up five root growth space （4 cm×20 cm，6 cm×20 cm，8 cm×20 cm，10 cm×20 cm，12 cm×20 cm） comparative experiments. Differences in seedling growth and root development were analyzed at the end of growing season. The seedling height， ground diameter， leaf area， total biomass， lateral root length， root volume， root amplitude， the proportion of 80°-90° lateral roots and lateral-root meristem length of F. mandshurica seedlings increased gradually with the increase of root growth space， while these indexes of L. gmelinii seedlings all increased first and then decreased with the increase of root growth space. With the enhancement of root restriction， the main root length of F. mandshurica seedlings gradually increased， the length of the main root in the minimum root growth space was about 1.5 times that in the maximum root growth space， the diameter of lateral roots at angles <60° for L. gmelinii seedlings gradually increased. Deep-rooted and shallow-rooted seedlings had different root restriction responses and root growth space requirements. When the root growth space was restricted， deep-rooted seedlings mainly resisted the influence of root restriction by increasing the length of the main root， while shallow-rooted seedlings enhanced their resistance mainly by increasing the diameter of lateral roots with smaller branch angles. The reduction of root growth space has a greater impact on the growth of deep-rooted seedlings， and the smaller the root growth space， the weaker the growth ability of seedlings； for shallow-rooted seedlings， moderate reduction of root growth space actually promotes root development and seedling growth.
Aiming at the difficulty of accurately recognizing the heartwood of larch standing trees， this study proposes an intelligent segmentation method based on electrical resistance tomography （ERT）. By comparing and analyzing ERT images and physical sections of larch samples， it is found that the resistance change rate of the junction region of the heart sapwood reached 90%-94%. Based on this threshold range， the segmentation annotation criterion for ERT image segmentation of larch standing tree heartwood was established. Due to the difficulty in acquiring ERT images， two datasets， Mini-200 small samples and Mids-3200 large samples， were constructed to quickly adapt to the segmentation task through the small training set， and combined with the large training set to improve the model robustness and reduce overfitting. The improved semantic segmentation network （DeepLabv3+） model was proposed to optimize its feature extraction capability by introducing ResNet101， convolutional block attention mechanism （CBAM） and data communication module （DCM）. The ablation experiments showed that the five evaluation indexes of accuracy （A）， precision （P）， intersection over union （IoU）， mean intersection over union （mIoU） and Dice loss function of the improved model were improved by 0.14%-0.44% compared with the base model on the Mini-200 dataset； on the Mids-3200 dataset， the improved DeepLabv3+ model had the optimal segmentation performance， and compared with the original model， the pixel accuracy （PA） and IoU of the heartwood were improved by 0.32% and 2.45%， respectively， and the class pixel accuracy （CPA）， mIoU and Dice coefficient were improved by 0.47%， 2.13%， 0.25%， respectively， and the IoU reached 98.80%， compared with the original model. It proves that the improved model works well for the segmentation of the heartwood of the ERT image of larch.
In forest harvesting operations， transportation routing and task scheduling are highly coupled. Traditional single-objective optimization approaches often fail to balance operational efficiency with ecological impact. This study proposes a multi-objective scheduling method integrating ecological disturbance control for coordinated optimization of harvesting and transportation. A multi-objective model is developed to minimize total transportation distance， makespan， and surface disturbance. Road-level disturbance coefficients and regional sensitivity factors are prominently introduced for refined assessment of surface disturbance. An improved non-dominated sorting genetic algorithm Ⅱ （NSGA-Ⅱ） is employed， utilizing specific encoding and evolutionary strategies for multi-objective optimization. Simulation results show that the proposed method reduces transportation distance by approximately 14.3% and surface disturbance by nearly 32% compared to greedy and ACO-based algorithms， while maintaining comparable completion times. The multi-objective compromise solution demonstrates superior to single objective extreme solutions in terms of the balance of three indicators. The method effectively reduces environmental disturbance without significantly sacrificing efficiency， achieves efficient coordination between scheduling optimization of forest harvesting tasks and ecological control， and is suitable for smart forestry scheduling scenarios under ecological constraints and showcasing strong potential for practical application.
As an important carrier of the national new energy strategy， the leakage of gas pressure pipelines in forest areas not only causes direct economic losses， but also may lead to secondary disasters such as soil pollution， vegetation destruction and even forest fires due to the sensitivity of forest ecosystems. The current ultrasonic sound source-based localization methods suffer from challenges such as high sidelobe artifact interference and insufficient localization accuracy caused by wide main lobe beamwidth in multi-leakage source scenarios. Moreover， the complex terrain， dense vegetation coverage， and environmental noise in forest areas further compromise the applicability of conventional detection techniques. In this paper， an adaptive inverse convolution beamforming algorithm is proposed to achieve high-precision leakage localization by optimising the weight matrix and the inverse convolution iteration strategy. Firstly， the initial weight matrix is constructed based on the minimum variance distortionless response （MVDR） criterion， and the weights are adjusted with adaptive iteration to enhance the focusing ability of the target signal while suppressing the interference of the sidelobes. Secondly， the main lobe width is compressed through Gauss-Seidel deconvolutional iteration， thereby enhancing resolution. To validate the algorithm's performance， this study establishes a pressure pipeline model with a diameter of 150 mm and operating pressure of 0.8 MPa to simulate ultrasonic signals from 0.5 mm and 0.7 mm leakage orifices， while constructing an experimental system for comparative analysis. Results demonstrate that compared with conventional deconvolution beamforming， the proposed algorithm reduces localization errors by 0.06 m for Source 1 （0.7 mm orifice） and 0.05 m for Source 2 （0.5 mm orifice） under signal-to-noise ratio （SNR） conditions ranging from -10 dB to 20 dB， while effectively eliminating artifact interference. The experiments further validate the method's robustness and computational efficiency advantages under low SNR conditions （-10 dB to 20 dB）. This study provides a high-precision solution for non-contact detection of minor pressure pipeline leaks in forest environments， characterized by strong anti-interference capability and superior environmental adaptability. The findings hold significant implications for ensuring energy transportation safety and ecological conservation.
