Search Results (17)

The temperate evergreen needleleaf forest (ENF), primarily composed of Mongolian Scots pine (Pinus sylvestris var. mongolica), plays a pivotal role in the “The Great Green Wall” Shelterbelt Project in northern China as a major species for windbreak and sand fixation. Solar-induced chlorophyll fluorescence (SIF) has emerged as a revolutionary remote sensing signal for quantifying photosynthetic activity and gross primary production (GPP) at the ecosystem scale. Meanwhile, eddy covariance (EC) technology has been widely employed to obtain in situ GPP estimates. Although a linear relationship between SIF and GPP has been reported in various ecosystems, it is mainly derived from satellite SIF products and flux-tower GPP observations, which are often difficult to align due to mismatches in spatial and temporal resolution. In this study, we analyzed synchronous high-frequency SIF and EC-derived GPP measurements from a Mongolian Scots pine plantation during the seasonal transition (August–December). The results revealed the following. (1) The ENF acted as a net carbon sink during the observation period, with a total carbon uptake of 100.875 gC·m⁻². The diurnal dynamics of net ecosystem exchange (NEE) exhibited a “U”-shaped pattern, with peak carbon uptake occurring around midday. As the growing season progressed toward dormancy, the timing of CO₂ uptake and release gradually shifted. (2) Both GPP and SIF peaked in September and declined thereafter. A strong linear relationship between SIF and GPP (R² = 0.678) was observed, consistent across both diurnal and sub-daily scales. SIF demonstrated higher sensitivity to light and environmental changes, particularly during the autumn–winter transition. Cloudy and rainy conditions significantly affect the relationship between SIF and GPP. These findings highlight the potential of canopy SIF observations to capture seasonal photosynthesis dynamics accurately and provide a methodological foundation for regional GPP estimation using remote sensing. This work also contributes scientific insights toward achieving China’s carbon neutrality goals. Full article

Mongolian pine (Pinus sylvestris var. Mongolia) has been widely utilized as a key species for afforestation projects within the Three-North Shelterbelt of Liaoning Province in China. Its impressive ecological resilience has made it a favorite choice for this endeavor. However, as the stands mature and climate conditions shift, some areas are experiencing premature decline or even mortality. Ecological stoichiometry is capable of uncovering the supply and equilibrium of plant and soil nutrients within ecosystems and is extensively utilized in the identification of limiting elements. Therefore, studying its ecological stoichiometry and internal stability dynamics is of crucial significance for clarifying the nutrient cycling process in the Mongolian pine region and alleviating the decline situation. The eastern and northwestern regions of Liaoning differ significantly in precipitation and soil nutrient availability. This study examines Mongolian pine plantations in both regions, analyzing the carbon (C), nitrogen (N), and phosphorus (P) content in plant tissues, soil, microbial biomass, and stoichiometric ratio under distinct environmental conditions. In order to provide a theoretical basis for alleviating the decline of artificial poplar forests and healthy management. Results indicate that (1) leaf C, N, and P contents in the eastern Liaoning region averaged 496.67, 15.19, and 1.66 g·kg⁻¹, respectively, whereas those in northwestern Liaoning were 514.16, 14.82, and 1.23 g·kg⁻¹, respectively. Soil C, N, and P concentrations exhibited notable regional differences, with eastern Liaoning recording 34.54, 2.62, and 0.48 g·kg⁻¹, compared to significantly lower values in northwestern Liaoning (7.74, 0.77, and 0.21 g·kg⁻¹). Similarly, microbial biomass C, N, and P were higher in eastern Liaoning (18.63, 5.09, and 7.72 mg·kg⁻¹) than in northwestern Liaoning (10.18, 3.46, and 4.38 mg·kg⁻¹). (2) The stoichiometric ratio of soil in the Mongolian pine plantations is higher than that in northwestern Liaoning, but the stoichiometric ratio of plants shows the opposite trend. Specifically, microbial carbon-to-nitrogen (MBC/MBN) ratios are higher in eastern Liaoning, whereas microbial carbon-to-phosphorus (MBC/MBP) and nitrogen-to-phosphorus (MBN/MBP) ratios are greater in northwestern Liaoning. Correlation analysis of plant–soil–microbe stoichiometry indicates that plant growth in both regions is co-limited by nitrogen, with Mongolian pine exhibiting strong internal stability. Full article

Accurate estimation of the potential increase in the carbon (C) sink function of forests is required for climate mitigation and C neutrality assessments. Also, accurate forest carbon density estimates are critical for understanding national- and global-level carbon cycling and storage and can inform climate change mitigation. This study established a stand C density growth model to further analyze the C sink potential of planted Mongolian pine (Pinus sylvestris var. mongolica) forests. Samples (390) from fixed plots of Mongolian pine were collected in Heilongjiang Province, Northeast China. The site index (SCI) and stand density index (SDI) were introduced to a constructed stand C density growth model, with an optimal model selected through model fitting. The effect of SDI on stand C density in different SCI grouping intervals was assessed. Total C sequestration of Mongolian pine was calculated using the established C density model. Sample plots with higher C density in each forest age stand were selected to establish a model of potential C sequestration for Mongolian pine, and the difference between this rate and the average was compared to obtain the potential increase in C sink capacity of the forest stand. Slightly different fitting accuracies among the different C density growth models were observed, with the Richards model showing the best performance, which improved through the introduction of the SCI and SDI. Stand C density was associated with an increasing trend in SCI, which within each SCI subgroup was related to the increasing SDI trend. The potential C sequestration rate of the stand was close to the average between years 5 and 13. The average C sequestration rate peaked at 3.86 Mg·ha⁻¹·year⁻¹ at year 13, whereas the potential C sequestration rate peaked at 4.42 Mg·ha⁻¹·year⁻¹ in year 15. A gap between the potential and average C sequestration rate existed between ages 13 and 45, indicating the possibility for an increased C sink function in this forest age range. The Richards growth model incorporating SCI and SDI provided a better reflection of the C density of the Mongolian pine plantation, and the established stand C sequestration rate model showed that the optimal increment in the plantation C sink function can be obtained between years 13 and 45. The results of this study can guide C sink management in the Mongolian pine plantation. Full article

Seasonal precipitation variance significantly alters soil water content, potentially inducing water stress and affecting plant transpiration in semiarid deserts. This study explored the effects of environmental variables and hydraulic conductance on whole-tree transpiration (E_T) in Mongolian pines (Pinus sylvestris var. mongolica) across different forest stages in the semiarid deserts of Northern China. We measured E_T using sap flow in mature (MMP), half-mature (HMP), and young (YMP) Mongolian pine plantations. Measurements included soil-leaf water potential difference (ΔΨ), atmospheric conditions, and soil moisture contents on sunny days, both in dry and wet periods. Seasonally variable rainfall distinctly affected soil moisture; during the dry periods, both stomatal and hydraulic conductance influenced E_T, whereas stomatal conductance primarily regulated it during the wet periods. Discrepancies between predicted and measured E_T were noticed: compared to the predicted E_T, the measured E_T was lower during dry periods while higher during wet periods. Hydraulic conductance (K_T) increased with tree height (H) and ΔΨ. The K_T values in the dry period were lower than those in the wet period, indicating that the hydraulic resistance in the dry period was higher. The hydraulic compensation occurred and was observed between 11:00 and 13:00, aligned with increased hydraulic resistance during dry periods. Decreasing hydraulic conductance intensified leaf water stress in dry periods, especially when photosynthetically active radiation (PAR) and vapor pressure deficit (VPD) were heightened, potentially increasing stomatal sensitivity to drought, promoting water conservation and plant survival. A linear relationship between predawn and midday leaf water potentials was noticed, indicating extreme anisohydric behavior across forest stages during dry and wet periods. Although stomatal and hydraulic conductance influenced E_T during the dry period, MMP and YMP were more susceptible to drought conditions. Understanding these dynamics could help evaluate semiarid desert ecological functions for water conservation amidst uneven seasonal precipitation in Northern China. Full article

The accurate assessment of forest biomass is vital to climate change mitigation. Based on forest survey data, stand biomass models can effectively assess forest biomass carbon at large scales. However, traditional stand biomass models have ignored the potential effects of the climate on stand biomass estimation. There is still a lack of research on whether or not and in what ways the effects of the climate reduce uncertainty in biomass estimation and carbon accounting. Therefore, two types of stand biomass models, including basic stand biomass models (BBMs) and climate-sensitive stand biomass models (CBMs), were developed and tested using 311 plantation plots of Korean pine (Pinus koraiensis Siebold & Zucc.), Korean larch (Larix olgensisi A. Henry), and Mongolian pine (Pinus sylvestris var. mongolica Litv.) in Northeast China. The two types of models were developed by applying simultaneous equations based on nonlinear, seemingly unrelated, regression (NSUR) to ensure additivity of the stand total and components biomass (root, stem, branch, and needle). The results of fitting and leave-one-out cross-validation (LOOCV) indicated that the CBMs performed better than the corresponding BBMs. The RMSEs of the stand total biomass decreased by 3.5% to 10.6% for the three conifer species. The influence of temperature-related climate variables on the biomass of stand components was greater than that of precipitation-related climate variables. The sensitivity of the three conifer species to climate variables was ranked as Korean pine > Mongolian pine > Korean larch. This study emphasizes the importance of combining climate variables in stand biomass models to reduce the uncertainty and climate effects in forest biomass estimation, which will play a role in carbon accounting for forest ecosystems. Full article

Afforestation is conducive to improving ecosystem service functions and ecosystem diversity in the Mu Us Sandy Land, however, the important attribute of biomass for Mongolian pine (Pinus sylvestris var. mongolica Litv.) plantations has yet to be accurately evaluated. This study aimed to develop additive allometric biomass equations for the species and evaluate biomass partitioning patterns within tree components. A total of 131 trees were measured for stem, branch, and leaf biomass by destructively sampling and tree climbing, with the latter as a supplement. For each biomass component, we tested three equations with the diameter at breast (D) alone, height (H) as additional, and diameter in combination with height (D²H) as predictors using the weighted least squared method. Weighted nonlinear seemingly unrelated regression was adopted to fit a system of additive allometric biomass equations utilizing the selected equations. A leave-one-out cross-validation method (the jackknife procedure) was used to assess the predictive ability. The biomass partitioning pattern was evaluated by calculating the ratios. The results revealed that the diameter alone is a good predictor for branches and foliage biomass estimates, while the stem requires H included to improve estimation accuracy. Mongolian pine allocates relatively more biomass to the crown (51.4%) compared to the stem (48.6%). Branch biomass fraction increased monotonously with increasing tree size while a reverse trend was observed for foliage. In conclusion, the additive models developed in this study provide a robust biomass estimation and can be extensively used to estimate Mongolian pine forests biomass in Mu Us Sandy Land. Full article

The application of domestic sewage sludge (SS) may affect plant growth and soil quality through altering nutrient availability. However, the effect of SS application on the plant–soil system in sandy soils is poorly understood. In this study, we established SS application treatment plots (SL, 25 t ha⁻¹) and control treatment plots without sewage sludge application (CK, 0 t ha⁻¹). SS was applied to the soil surface of a Mongolian pine (Pinus sylvestris var. mongolica) plantation in Horqin Sandy Land, Inner Mongolia, China, to assess its potential effects on plants and soil. We analyzed tree growth performances (tree height, basal diameter, and diameter at breast height), understory traits (species diversity, coverage, and aboveground biomass), soil physical and chemical parameters (nutrient content, dissolved organic carbon, soil water content, bulk density, pH), and proxies of ecosystem services (soil organic carbon and total nitrogen stocks). The results showed that SS addition not only significantly increased soil nutrient contents, but also markedly enhanced aboveground productivity and plant coverage. Specifically, SS addition decreased soil bulk density and increased concentrations of soil organic carbon, total nitrogen, and total phosphorus and mineral nitrogen, and it also increased soil carbon and nitrogen stocks. Furthermore, the addition of SS significantly increased soil dissolved organic carbon contents and enhanced the fluorescence intensities of dissolved organic carbon components (humic acid-like and UV fulvic acid-like) in the topsoil (0–5 cm). This study provides evidence that SS is an acceptable, and possibly preferred organic fertilizer for improving the soil quality and tree–grass growth of Mongolian pine plantations. Full article

Forest degradation and mortality have been widely reported in the context of increasingly significant global climate change. As the country with the largest total tree plantation area globally, China has a great responsibility in forestry management to cope with climate change effectively. Mongolian Scots pine (Pinus sylvestris var. mongolica) was widely introduced from its natural sites in China into several other sandy land areas for establishing shelterbelt in the Three-North Shelter Forest Program, scoring outstanding achievements in terms of wind-breaking and sand-fixing. Mongolian Scots pine plantations in China cover a total area of ~800,000 hectares, with the eldest trees having >60 years. However, plantation trees have been affected by premature senescence in their middle-age stages (i.e., dieback, growth decline, and death) since the 1990s. This phenomenon has raised concerns about the suitability of Mongolian Scots pine to sandy habitats and the rationality for further afforestation, especially under the global climate change scenario. Fortunately, dieback has occurred only sporadically at specific sites and in certain years and has not spread to other regions in northern China; nevertheless, global climate change has become increasingly significant in that region. These observations reflect the strong drought resistance and adaptability of Mongolian Scots pines. In this review, we summarized the most recent findings on the ecohydrological attributes of Mongolian Scots pine during its adaptation to both fragile habitats and climate change. Five main species-specific strategies (i.e., opportunistic water absorb strategy, hydraulic failure risk avoidance strategy, water conservation strategy, functional traits adjustment strategy, rapid regeneration strategy) were summarized, providing deep insights into the tree–water relationship. Overall, the findings of this study can be applied to improve plantation management and better cope with climate-change-related drought stress. Full article

Height-diameter (H-D) models are important tools for forest management practice. Sandy Mongolian pine plantations (Pinus sylvestris var. mongolica) are a major component of the Three-North Afforestation Shelterbelt in Northern China. However, few H-D models are available for Mongolian pine plantations. In this paper we compared different equations found in the literature for predicting tree height, using diameter at breast height and additional stand-level predictor variables. We tested if the additional stand-level predictor variable is necessary to produce more accurate results. The dominant height was used as a stand-level predictor variable to describe the variation of the H-D relationship among plots. We found that the basic mixed-effects H-D model provided a similar predictive accuracy as the generalized mixed-effects H-D model. Moreover, it had the advantage of reducing the sampling effort. The basic mixed-effects H-D model calibration, in which the heights of the two thickest trees in the plot were included to calibrate the random effects, resulted in accurate and reliable individual tree height estimations. Thus, the basic mixed-effects H-D model with the above-described calibration design can be an accurate and cost-effective solution for estimating the heights of Mongolian pine trees in northern China. Full article

This study aimed to evaluate the seasonal variations of Greenhouse Gas fluxes (CH₄, CO₂, and N₂O), Greenhouse Gas (GHG) emissions, and Global Warming Potential (GWP) over the extent of the regions and understand the controlling factors. CH₄, CO₂, and N₂O fluxes were measured along with their environmental variables from the over-mature forest, Korean pine plantation, and five 60-year-old natural secondary forests in mountainous regions in Northeast China from May 2015 to April 2016. The results revealed that secondary forests, except for Betula platyphylla forest, significantly increased CH₄ absorption by 19.6% to 51.0% and 32.6% to 67.0% compared with over-mature forest (OMF) and Korean pine plantation (KPP). Five secondary forests significantly increased CO₂ flux by 32.9% to 78.6% and 14.1% to 53.4% compared with OMF and KPP, respectively. According to the annual statistics, the N₂O fluxes had significant differences among seven forest types and decreased in the following order: mixed deciduous forest (MDF) > OMF > KPP > Populous davidiana forest (PDF) > hardwood forest (HWF) > Mongolian oak forest (MOF) > Betula platyphylla forest (BPF). The CH₄ absorption and CO₂ emission peaks occurred in summer, while the peak N₂O fluxes occurred in spring. Stepwise multiple linear regression showed that CH₄ and CO₂ fluxes from soils were strongly influenced by air and soil temperature, soil volumetric water content (SVWC), nitrate nitrogen (NO₃⁻-N), ammonium nitrogen (NH₄⁺-N), and soil organic carbon (SOC) across the whole year. Air temperature, SVWC, pH, NO₃⁻-N, and NH₄⁺-N were the dominant factors controlling N₂O fluxes from OMF and five secondary forests (except for BPF). No significant relationships were observed between these environmental factors and N₂O fluxes from KPP and BPF. Additionally, the total cumulative CH₄, CO₂, and N₂O fluxes were –13.37 t CH₄ year⁻¹, 41,608.96 t CO₂ year⁻¹, and 3.24 t N₂O year⁻¹, and the total cumulative GWP were 42,151.87 t CO₂ eq year⁻¹ through the whole year in seven forest types at the Maoershan Ecosystem Research Station in Northeast China. For the annual GWP per hectare, secondary forests and KPP averaged a higher GWP by 33.7%–80.1% and 17.9% compared with OMF. This indicates that the effects of early human activities have not been completely eliminated in the middle stage of KPP and secondary forests. Full article

The effects of replacing over-mature forest with secondary forests and plantations are significant for terrestrial ecosystem carbon (C) dynamics. However, the carbon balance and recovery time of this replacement process remain unclear. This study measured the fluxes of CH₄ and CO₂ in soils and the annual net C sequestration (ANCS) from seven ecosystems with different vegetation types (over-mature forest (OMF), Korean pine plantation (KPP), hardwood forest (HWF), Betula platyphylla forest (BPF), Populous davidiana forest (PDF), mixed deciduous forest (MDF), and Mongolian oak forest (MOF)) using the static chamber-gas chromatography method and the relative growth equation method. We examined the effects of environmental factors (e.g., air and soil temperature, soil volumetric water content (SVWC), soil pH, nitrate nitrogen (NO₃⁻-N), ammonium nitrogen (NH₄⁺-N), and soil organic carbon (SOC)) on CH₄ and CO₂ fluxes at the Maoershan Ecosystem Research Station in Northeast China. The carbon source or sink of OMF, KPP, and five secondary forests (HWF, BPF, PDF, MDF, and MOF) were then evaluated based on net ecosystem C balance. The results revealed that the mean annual CH₄ fluxes varied between −0.046 and −0.077 mg m⁻² h⁻¹. The mean annual absorption of CH₄ in the secondary forests and OMF were respectively 1.09–1.67 times and 1.11 times higher than that of KPP (0.046 mg m⁻² h⁻¹, p < 0.05). The mean annual CO₂ fluxes varied between 140.425 and 250.023 mg m⁻² h⁻¹. The CO₂ fluxes in the secondary forests and KPP soils were respectively 1.33–1.78 times and 1.16 times higher than that of OMF (140.425 mg m⁻² h⁻¹, p < 0.05). The CH₄ and CO₂ fluxes were mainly influenced by air and soil temperature, SVWC, soil pH, NO₃⁻-N, NH₄⁺-N, and SOC in Northeast China. The ANCS of vegetation (3.41 ± 0.27 − 6.26 ± 0.75 t C ha⁻¹ y⁻¹) varied widely among different forest types: KPP had the largest ANCS (6.26 ± 0.75 t C ha⁻¹ y⁻¹, which was higher than secondary forests and OMF by 1.20–1.84 times and 1.46 times, respectively, p > 0.05). Carbon sources and sinks were significantly different among the seven types of vegetation: OMF and KPP were observed to be the greatest C sinks, and secondary forests were shown to be the weakest carbon sinks or net C sources in the study region. Full article

The Mongolian pine (Pinus sylvestris var. mongolica) is one of the most common tree species in semiarid and arid areas of China, especially in the sand dunes of the Hulunbeier steppe. This study addresses the morphological and physiological characteristics of the Mongolian pine according to sand dune height. Five sites were chosen with various sand dune heights (P1–P5). Nine years after planting, tree growth, leaf area, leaf mass per leaf unit area (LMA), diameter at breast height (DBH), tree height, diameter at root collar (DRC), longest shoot length, carbon isotope composition, and intrinsic water use efficiency (iWUE) were measured to explore the responses of Mongolian pine trees to drought. DBH, tree height, DRC, leaf area, leaf length, and longest shoot length significantly decreased with greater sand dune height (p < 0.05). However, the carbon isotope actually increased with dune height (p < 0.05). Conversely, the iWUE of current-year pine needles was significantly higher at measurement points P3 (132.29 μmol CO₂ mol ⁻¹ H₂O), P4 (132.96 μmol CO₂ mol ⁻¹ H₂O), and P5 (125.34 μmol CO₂ mol ⁻¹ H₂O) than at the lower points P1 (95.18 ± 9.87 μmol CO₂ mol ⁻¹ H₂O) and P2 (103.10 ± 11.12 μmol CO₂ mol ⁻¹ H₂O). Greater sand dune height increases the distance to groundwater, which in this study led to an increase in iWUE in the Mongolian pines, thus these trees appear to adapt to increased sand dune height by increasing their iWUE and decreasing their leaf area. However, prolonged periods characterized by such adaptations can lead to tree death. We expect these findings to be useful when selecting plantation sites for Mongolian pines in semiarid and arid climates. Full article

The Mongolian pine (Pinus sylvestris L. var. mongolica Litv.) was first introduced to the southeastern Horqin sandy land in the mid-1950s. Since then, it has been widely planted and has become the most important conifer species in Northern China, providing significant ecological, economic and social benefits. However, its function in sequestering carbon at different developmental stages has been little studied. In this study, twenty plots inventory and destructive sampling of eight trees were conducted in 12-, 19-, 34-, 48- and 58-year-old Mongolian pine stands of China. Allometric biomass equations (ABEs) for tree components were established and used to determine the magnitude and distribution of tree biomass and carbon density. The carbon density of the understory, forest floor and soil was also determined. The ABEs with age as the second variable could simply and accurately determine the biomass of plantation tree branches, foliage and fruit, which were considerably influenced by age. With increasing stand age, the proportion of stem biomass to total tree biomass increased from 22.2% in the 12-year-old stand to 54.2% in the 58-year-old stand, and the proportion of understory biomass to total ecosystem biomass decreased, with values of 7.5%, 4.6%, 4.4%, 4.1% and 3.0% in the five stands. The biomass of the forest floor was 0.00, 1.12, 2.04, 6.69 and 3.65 Mg ha⁻¹ in the five stands. The ecosystem carbon density was 40.2, 73.4, 92.9, 89.9 and 87.3 Mg ha⁻¹ in the 12-, 19-, 34-, 48-, and 58-year-old stands, in which soil carbon density accounted for the largest proportion, with values of 67.4%, 76.8%, 73.2%, 63.4%, and 57.7% respectively. The Mongolian pine had the potential for carbon sequestration during its development, especially in the early stages, however, in the later growth stage, the ecosystem carbon density decreased slightly. Full article

Expected changes in precipitation over large regions of the world under global climate change will have profound effects on terrestrial ecosystems in arid and semiarid regions. To explore how changes in the amount of precipitation in the growing season would affect soil nitrogen (N) availability in a semiarid ecosystem, we established rainout shelters and irrigation systems by simulating 30% reduced (DRY) and 30% increased precipitation (WET) relative to natural precipitation (Control) to measure some key soil process properties for two growing seasons in a nutrient-poor Mongolian pine (P. sylvestris var. mongolica) plantation. Both WET and DRY treatments significantly affected monthly soil inorganic nitrogen concentrations, which showed a higher inorganic N under DRY than Control in each month and lower in WET than Control. Monthly soil microbial biomass N content was reduced by DRY and raised by WET treatments. The results indicated the asynchrony of the availability of soil moisture and soil nutrients in Mongolian pine plantations at the Horqin Sandy Lands in Northeast China. Water limited plant growth in Mongolian pine plantations when precipitation decreased, and nitrogen limitation became increasingly important when precipitation increased. Accumulation of N in microbial biomass is an important mechanism for N cycling in this ecosystem. To effectively manage Mongolian pine plantations, it is advised that evapotranspiration is minimized when precipitation decreases and that there is an increase in soil N availability by protecting litterfall when precipitation increases. Full article

Accurate quantification of tree biomass is critical and essential for calculating carbon storage, as well as for studying climate change, forest health, forest productivity, nutrient cycling, etc. Tree biomass is typically estimated using statistical models. In this study, a total of 289 trees were harvested and measured for stem, root, branch, and foliage biomass from three coniferous plantation species in northeastern P.R. China. We developed two additive systems of biomass equations based on tree diameter (D) only and both tree diameter (D) and height (H). For each system, likelihood analysis was used to verify the error structures of power functions in order to determine if logarithmic transformation should be applied on both sides of biomass equations. The model coefficients were simultaneously estimated using seemingly unrelated regression (SUR). The results indicated that stem biomass had the largest relative contribution to total biomass, while foliage biomass had the smallest relative proportion for the three species. The root to shoot ratio averaged 0.27 for Korean pine, 0.25 for larch, and 0.23 for Mongolian pine. The two additive biomass systems obtained good model fitting and prediction performance, of which the model R_a² > 0.80, and the percent mean absolute bias (MAB%), was <17%. The second additive system (D and H) had a relatively greater R_a² and smaller root mean square error (RMSE). The model coefficient for the predictor H was statistically significant in eight of the twelve models, depending on tree species and biomass component. Adding tree height into the system of biomass equations can marginally improve model fitting and performance, especially for total, aboveground, and stem biomass. The two additive systems developed in this study can be applied to estimate individual tree biomass of three coniferous plantation species in the Chinese National Forest Inventory. Full article