Pinus Sylvestris Var Research Articles

Sensitivity of Stand-Level Biomass to Climate for Three Conifer Plantations in Northeast China

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.

Effects of Shelterbelt Transformation on Soil Aggregates Characterization and Erodibility in China Black Soil Farmland

Farmland shelterbelts are widely used to reduce wind erosion, maintaining the ecological and food security of the black soil plain region of northeast China. In recent years, the protective effect of shelterbelts has been reduced due to tree degeneration. Efforts have been made to transform the construction of shelterbelts to conserve the stability of soil aggregates and enhance protection against erosion, however, the results are not well understood. To evaluate the impact of shelterbelt transformation on the stability of farmland soil aggregates and soil erodibility, three transformation modes of shelterbelts were selected, including pure Pinus sylvestris var. mongolica (ZC), pure Picea asperata (YS), and mixed Populus × xiaohei–Pinus sylvestris var.mongolica (ZY), with a degraded Populus × xiaohei shelterbelt (TYC) used as a control. We set up soil sampling points at 0.5H, 1H, 1.5H, 3H, 5H, 7H, and 9H from the shelterbelts and analyzed aggregate composition, mean weight diameter (MWD), geometric mean diameter (GMD), fractal dimension (D), soil erodibility (K-value), and their relationships to soil properties of the 0–10 cm, 10–20 cm and 20–40 cm soil layers and the shelterbelt structure by using dry and wet sieving and equation estimation methods. The results show that dry (d) sieved soil samples from the transformed shelterbelt-protected farmlands are mainly composed of 2–5 mm and >5 mm grain size aggregates; the sum of the two particle sizes ranged from 48.67% to 51.27%, significantly larger than in the degraded shelterbelts (15.37%), decreasing with increasing distance from the shelterbelts. The effect is most obvious in the 0–10 cm soil layer. Wet (w) sieved soil samples are all dominated by <0.25 mm and 0.25–0.5 mm grain size aggregates; the sum of the two particle sizes ranged from 78.25% to 80.82%, which do not vary significantly with the mode of shelterbelts. The dMWD and dGMD show significantly higher mean values in samples from transformed shelterbelt-protected farmland than in soil from degraded shelterbelt-protected farmland; their magnitudes differ depending on the transformation mode, showing a pattern of ZC > ZY > YS and decreasing with increasing distance from shelterbelts, while the opposite is true for D and K. The difference between wMWD and wGMD for different shelterbelts protected farmland is not significant and is significantly lower than that between dMWD and dGMD. Clay and silt content was highly significantly positively correlated with aggregates dMWD and dGMD, weakly positively correlated with wMWD, wGMD and wD, and highly significantly negatively correlated with dD and K values. This shows that particle composition parameters can be used to reflect the sensitivity of agricultural soils to wind erosion. Farmland shelterbelt porosity is the main factor driving changes in soil aggregates stability, soil erodibility, and other soil properties. The transformation of degraded farmland shelterbelts can decrease the porosity and reduce wind speed, resulting in improved stability and erosion resistance of the farmland soil aggregates by increasing the clay content of the farmland soils. These results are useful in renovating degraded shelterbelts, providing novel insights into how to regulate the stability of soil aggregates and soil erodibility characteristics at the shelterbelt network scale.

Radial and seasonal variation of sap flow and its response to meteorological factors in sandy Pinus sylvestris var. mongolica plantations in the Three North Shelterbelt of China

Mongolian Scots pine (Pinus sylvestris var. mongolica) is one of the main afforestation tree species in the Three North shelterbelt project in China, and an accurate estimation of its transpiration is of importance for plantation scientific density management especially under future climate change scenarios. While radial variation in tree species sap flow is an important factor for estimating transpiration, it is usually neglected. Thus, this study selected Mongolian Scots pine of different ages (10a, 20a, 30a, 40a) to study its radial variation pattern of sap flow using the multipoint (probes of different specifications) thermal dissipation method; additionally, its response characteristics to meteorological factors in northeast China were also discussed. The results show that the radial distribution of the sap flux density varied with age and growing season. It gradually decreased from the outside to the inside of the sapwood of the 10a stand. In contrast, the sap flux densities of the 20a, 30a and 40a stands had all typical single-peak patterns, with the highest value at 15 mm from the outside of the sapwood, and then sharply decreased with increasing distance. The sap flux density in both the 10a and 20a stands slightly changed, while it a significantly change in both the 30a and 40a stands between the middle and end of the growing season occurred. Further estimation of transpiration by single point and multipoint analyses was undertaken. The single point analysis resulted in large errors of -18.81%-11.02%, -52.44%-133.47%, -10.26%-130.38% and -48.78%-162.11% in the 10a, 20a, 30a and 40a stands, respectively. However, Js15mm was significantly correlated with the mean sap flux density of a sapwood area (Jsmean) and exhibited a constant conversion coefficient. The sap flux densities of separate sapwood depths were significantly affected by meteorological factors and varied according to different meteorological factors.

Additive Allometric Equations to Improve Aboveground Biomass Estimation for Mongolian Pine Plantations in Mu Us Sandy Land, Inner Mongolia, China

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.

Biogeography and ecological functions of root‐associated and soil fungi of Pinus sylvestris var. mongolica across different afforestation areas in desertified Northern China

AbstractChina has unquestionably led efforts to 'green' drylands, but an evaluation of the large‐scale effects of afforestation in desert ecosystems mediated by soil microorganisms is lacking. The ecological functions of fungi are closely related to soil and plant health. Therefore, there is a lively interest in revealing the biogeographic patterns of root‐associated (RAF) and soil fungal (SF) communities of Pinus sylvestris var. mongolica, a widespread evergreen tree endemic to Northern China. We revealed the community assembly of RAF and SF of natural forest and plantations in the Hulunbuir Desert, Horqin Desert, and Mu Us Desert and investigated fungal responses to geographical location, climate factors, soil properties, and stand age at regional and local scales. The results indicated that (1) SF was more diverse than RAF. For RAF, the diversity indices in the natural forest were significantly lower than those in plantations, and ectomycorrhizal fungi (50.37%) were the predominant functional guild in the natural forest. (2) At the local scale, SF, not RAF, is more sensitive to the impacts of soil properties. More than half of the differential genera were ectomycorrhizal and endophytic fungi, such as Acephala, Cadophora, Pustularia, and Trichoderma. (3) On the regional scale, precipitation and sunshine duration were the main influences on geographical differences in the fungal community composition. Geographical location directly and significantly influences RAF diversity and structure. The effect of climate factors on SF diversity was low, but it had a shaping effect on SF structure. Our results demonstrated that the fungal communities were geographically structured, a stable relationship was established between hosts and RAF, and soil nutrients had a significant impact on SF community composition. The ecological functions of fungi are important in evaluating afforestation efforts and maintaining stability in desert ecosystems.

Rainfall interception using the revised Gash analytical model for Pinus sylvestris var. mongolica in a semi-humid region of NE China

Rainfall loss by canopy interception comprises a substantial portion of the water budget in forested ecosystems, and accurately measuring and simulating this process is critical for the effective management of forest water resources. Pinus sylvestris var. mongolica is a main afforested species in northeastern China; however, little work has been carried out assessing the canopy interception loss of this plant species in semi-humid areas. Accordingly, a rainfall interception experiment was conducted for P. sylvestris plots in a semi-humid area of northeastern China from June to September 2019. The revised Gash analytical model was then applied to the canopy interception values, and its regional applicability was tested. During the experimental process, incident rainfall (P), throughfall (Tf), and stemflow events (Sf) were collected and measured, while meteorological data were simultaneously obtained on-site. The Penman (PM) equation and the Gash regression method were used to estimate evaporation rates (E) from the saturated canopy, and the Leyton constraint method was applied to obtain canopy storage capacity (S). Parameters such as E, S, stemflow partitioning coefficient (pt), and trunk storage capacity (St) were scaled to the canopy cover fraction per unit area (producing Ec, Sc, ptc, and Stc in the revised Gash analytical model, respectively) for use in the simulated rainfall interception. The proportions of measured canopy interception (I), Sf, and Tf accounted for 17.2 %, 6.0 %, and 76.8 % of P, respectively; whereas the Sc, ptc, and Stc were calculated as 1.60 mm, 0.067, and 0.21 mm, respectively, over the experimental period. The revised Gash analytical model with Ec varied from 0.37 to 0.93, and Ec/R varied from 0.62 to 1.55 (acquired via the PM equation), thus indicating its ability to accurately simulate P. sylvestris canopy interception. These findings can provide a theoretical foundation for understanding correlated ecological and hydrological processes, allowing land managers to predict the impacts of afforestation on water inputs for current and future rainfall scenarios in typical coniferous forests of semi-humid regions.

Plant Growth-Promoting Rhizobacteria Promote Growth of Seedlings, Regulate Soil Microbial Community, and Alleviate Damping-Off Disease Caused by Rhizoctonia solani on Pinus sylvestris var. mongolica.

As the excessive use of chemical fertilizers harms organisms and adversely affects the soil environment, the replacement of chemical fertilizers with biological fertilizers has attracted widespread attention as an environmental protection strategy. In this study, the effects of rhizosphere bacteria inoculation on growth of Pinus sylvestris var. mongolica seedlings, soil parameters, soil microbial community structure, and the biocontrol of damping-off were studied by pot experiments. The results showed that all three rhizosphere bacteria (Pseudomonas chlororaphis, Pseudomonas extremaustralis, and Acinetobacter lwoffii A07) tested exhibited growth-promoting properties, such as the production of indole-3-acetic acid, hydrolase, siderophores, and hydrogen cyanide; nitrogen fixation; and phosphorus solubilization. The application of the three bacteria increased plant biomass, root structure, and nutrient content and also increased soil nutrient content and enzyme activity. Bacterial inoculation promoted the growth of beneficial bacteria and antagonistic bacteria by adjusting the physicochemical properties of the soil, thereby improving the bacterial community structure. Among the soil features, available nitrogen, total nitrogen, available potassium, and urease activity were the main influencing factors. In addition, it was also found that bacterial inoculation significantly increased the activities of plant superoxide dismutase, catalase, peroxidase, and other defense enzymes; enhanced plant disease resistance; effectively inhibited damping-off; and promoted plant growth. In summary, the application of three rhizosphere bacteria systematically affected the interaction between plants, soil parameters, and soil microbial communities. These results provide a basis for understanding how rhizosphere bacteria promote the growth of P. sylvestris var. mongolica, thereby offering a promising sustainable alternative to chemical fertilizers.

An Integrated Method for Estimating Forest-Canopy Closure Based on UAV LiDAR Data

Forest-canopy closure (FCC) reflects the coverage of the forest tree canopy, which is one of the most important indicators of forest structure and a core parameter in forest resources investigation. In recent years, the rapid development of UAV LiDAR and photogrammetry technology has provided effective support for FCC estimation. However, affected by factors such as different tree species and different stand densities, it is difficult to estimate FCC accurately based on the single-tree canopy-contour method in complex forest regions. Thus, this study proposes a method for estimating FCC accurately using algorithm integration with an optimal window size for treetop detection and an optimal algorithm for crown-boundary extraction using UAV LiDAR data in various scenes. The research results show that: (1) The FCC estimation accuracy was improved using the method proposed in this study. The accuracy of FCC in a camphor pine forest (Pinus sylvestris var. mongolica Litv.) was 89.11%, with an improvement of 6.77–11.25% compared to the results obtained from other combined conditions. The FCC accuracy for white birch (White birch platyphylla Suk) was about 87.53%, with an increase of 3.25–8.42%. (2) The size of the window used for treetop detection is closely related to tree species and stand density. With the same forest-stand density, the treetop-detection window size of camphor pine was larger than that of white birch. The optimal window size of camphor pine was between 5 × 5~11 × 11 (corresponding 2.5~5.5 m), while that of white birch was between 3 × 3~7 × 7 (corresponding 1.5~3.5 m). (3) There are significant differences in the optimal-canopy-outline extraction algorithms for different scenarios. With a medium forest-stand density, the marker-controlled watershed (MCW) algorithm has the best tree-crown extraction effect. The region-growing (RG) method has better extraction results in the sparse areas of camphor pine and the dense areas of white birch. The Voronoi tessellation (VT) algorithm is more suitable for the dense areas of camphor pine and the sparse regions of white birch. The method proposed in this study provides a reference for FCC estimation using high-resolution remote-sensing images in complex forest areas containing various scenes.

Comparison of Modeling Approaches for the Height–diameter Relationship: An Example with Planted Mongolian Pine (Pinus sylvestris var. mongolica) Trees in Northeast China

In the process of modeling height–diameter models for Mongolian pine (Pinus sylvestris var. mongolica), the fitting abilities of six models were compared: (1) a basic model with only diameter at breast height (D) as a predictor (BM); (2) a plot-level basic mixed-effects model (BMM); (3) quantile regression with nine quantiles based on BM (BQR); (4) a generalized model with stand or competition covariates (GM); (5) a plot-level generalized mixed-effects model (GMM); and (6) quantile regression with nine quantiles based on GM (GQR). The prediction bias of the developed models was assessed in cases of total tree height (H) predictions with calibration or without calibration. The results showed that extending the Chapman–Richards function with the dominant height and relative size of individual trees improved the prediction accuracy. Prediction accuracy was improved significantly when H predictions were calibrated for all models, among which GMM performed best because random effect calibration provided the lowest prediction bias. When at least 8% of the trees were selected from a new plot, relatively accurate and low-cost prediction results were obtained by all models. When predicting the H values of Mongolian pine for a new stand, GMM and BMM were preferable if there were available height measurements for calibration; otherwise, GQR was the best choice.

First Report of Black Spot Needle Blight of Pinus sylvestris var. mongolica Litv. Caused by Heterotruncatella spartii in China.

Pinus sylvestris var. mongolica Litv. (Pinales: Pinaceae) is an excellent tree for soil and water conservation in Northeast China. The Honghua'erji area in Inner Mongolia is the "hometown of P. sylvestris var. mongolica", however, in recent years, coniferous diseases of P. sylvestris var. mongolica have frequently occurred here. During the investigation, it was found that some black spot needle blight had been observed in addition to the common blight caused by Sphaeropsis sapinea. From May to September 2020, black spot needle blight was found on hundreds of P. sylvestris var. mongolica trees in four forest farms, and the infection rate among the forests was 24.58 % (n=240). This disease first appeared on the upper part of the needles, and the needles then became withered and gradually showed light black spots, although they remained green. As the disease progressed, the needles eventually died and turned gray with many dark black spots. Fungal isolate named YJ-1 was obtained from infected needles of symptomatic pine trees, and a voucher specimen was deposited in Heilongjiang Province Key Laboratory of Forest Protection. Microscopic observation showed the conidia were 3-septate (4 cells) clavate spindles that measured 23.9 μm (20.8-25.9) × 5.9 μm (4.5-8.2) (n=50). The middle two cells were dark brown, and the septa were darker than the cells. Both apical and basal cells were hyaline. The apical cell had 2-4 appendages (mostly 3), and the basal cell had a truncate base (n=50). The cultural characteristics on potato dextrose agar medium were flat off-white and dense in 3-5 d. At approximately 5-7 d, the reverse side of the colony turned pale to slightly luteous. Superficial black acervuli were distributed in the center of the mature colonies after 10 d. Morphological, cultural and microscopic characteristics observed were similar of Heterotruncatella spartii (basionym: Truncatella spartii) reported by Hlaiem et al (2019). To further identify, total DNA was extracted and the internal transcribed spacer region (ITS-rDNA) was amplified by PCR using the primers ITS1/ITS4 and sequenced for BLASTn analysis and phylogenetic tree construction. The resulting 564 bp sequence (GenBank Accession No. OL662864) had 99.24% (521/525) to H. spartii MFLUCC 15-0537, with bootstrap support of at least 94% using the Neighbor-Joining algorithm by MEGA-X (Felsenstein, 1985). The fungus was identified as H. spartii based on morphology and molecular methods. A pathogenicity test was conducted by preparing a conidial suspension of 2.0 × 107 conidia/mL. The suspension was sprayed onto the needles of 20 pots of annual P. sylvestris ar. mongolica seedlings, and the control was sprayed with sterile water. Then the seedlings were placed in a constant temperature room at 25 °C. After 30 d, typical symptoms appeared on 11 inoculated needles, while the control needles remained symptomless. After 50 d, the re-isolation infection rate reached 66.7 %. The fungus present on the inoculated seedlings was morphologically identical to that originally observed on diseased pines, fulfilling Koch's postulates. The fungus was isolated from Spartium junceum for the first time and designated Truncatella spartii (Senanayake et al, 2015). It was then renamed H. spartii (Liu et al, 2019) and has been reported to infect P. pinea in Tunisia (Hlaiem et al, 2019). To our knowledge, this is the first report of H. spartii causing black spot needle blight on P. sylvestris var. mongolica in China and worldwide.

Effects of Forest Types on SOC and DOC in the Permafrost Region of the Daxing’anling Mountains

There is a “symbiotic relationship” between permafrost and the forest ecosystem; the melted permafrost provides sufficient water for forest growth, and the forest ecosystem plays an important role in protecting the permafrost. Aiming to study the effects of different forest types on soil organic carbon (SOC) and dissolved organic carbon (DOC) in the permafrost region of the Daxing’anling Mountains, this research focuses on the soil of the three forest types of pinus sylvestris var. mongolica forest, larch forest, and birch forest in Beiji Village, Mohe County, Daxing’anling Region, and collected vertical profile soil samples from the three soil layers of 0–10, 10–20, and 20–30 cm at three different sites types (upslope, mesoslope, and downslope) in August 2017. The results show that the forest type is the main influencing factor for the content of SOC and DOC. The site type has a significant effect on the content of SOC and DOC in the three forest types, but the difference varies slightly (p > 0.05). The content of SOC and DOC is negatively correlated with the depth of the soil layer of the vertical profile. The geodetector data analysis shows that there are significant differences (p < 0.05) among the contents of SOC and DOC in the three forest types. In conclusion, this study contributes to an in-depth understanding of carbon storage, the carbon dynamics of SOC, and the effects of different forest types on carbon balance in permafrost regions, and it provides a scientific basis for the study of the carbon cycle mechanism in permafrost regions.

Effects of roasting treatment on functional properties and structure of proteins in grafted Korean pine

Effects of roasting treatment on functional properties and structure of pine kernel protein from two grafted species: Pinus koraiensis (PK) and Pinus sylvestris var. (PKS) were evaluated by analysis of SDS-PAGE, FTIR, fluorescence spectrum, solubility, emulsifying properties, etc. The results showed that roasting improved functional properties of PK and PKS. Structure analysis elucidated that conformational changes of tertiary structure, occurrence of unfolded protein structure, and enhancement in α-helix and random coil structures. For PK, solubility, emulsifying and oil holding capacity (OHC) were the highest at 150 °C, 20 min. PKS had the highest emulsification and OHC at 150 °C, 10 min. The improvements in functional properties of PK and PKS should be attributed to the influence of intramolecular intergroup forces on secondary and tertiary structures, which resulted in higher surface charges and reduced turbidity. This study provided a reference for moderating quality properties of two kinds pine kernel.

Effects of Sewage Sludge Application on Plant Growth and Soil Characteristics at a Pinus sylvestris var. mongolica Plantation in Horqin Sandy Land

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.

High adaptability of Pinus sylvestris var. mongolica to drought-induced soil nutrient deficiency

Abstract Background Drought can exert a profound influence on soil nutrient availability, and understanding whether and how tree species adapt to this change is a critical priority for predicting the consequence of climate change on forest structure and function. The objective of this study was to examine the adaptability of Mongolian pine (Pinus sylvestris var. mongolica) to drought-induced changes in soil nutrient availability from the perspective of root functions. Methods We conducted a 7-year precipitation manipulation experiment with three levels of throughfall reduction (0%, 30%, and 50%) to simulate different drought intensities. We measured soil physicochemical properties and fine-root nutrient concentrations and biomass, and calculated the stoichiometric homeostatic regulation coefficient (1/H) of fine roots. Results Drought reduced soil organic carbon (C), nitrogen (N), phosphorous (P) and inorganic N concentrations, as well as ratios of total N to total P, and available N to available P in the 0–20 cm soil layer. In contrast, drought had no significant effect on fine-root N and P concentrations, and fine-root biomass in the 0–40 cm soil layer. Fine roots displayed high homeostatic regulation coefficients of N (with 1/H values of 0.19 and 0) and P (with 1/H values of 0.33 and 0) concentrations in 0–20 and 20–40 cm soil layers, respectively. Conclusions Our results indicate that drought leads to soil nutrient deficiency and the decoupling between N and P cycling, and provide evidence that Mongolian pine has high adaptability to drought-induced decrease in soil nutrient availability by maintaining great fine-root biomass to ensure sufficient nutrient uptake.

Radial Growth of Trees Rather Than Shrubs in Boreal Forests Is Inhibited by Drought.

Of all forest biomes, boreal forests are experiencing the most significant warming. Drought caused by warming has a dramatic impact on species in boreal forests. However, little is known about whether the growth of trees and shrubs in boreal forests responds consistently to warming and drought. We obtained the tree-ring width data of 308 trees (Larix gmelinii and Pinus sylvestris var. mongolica) and 133 shrubs (Pinus pumila) from 26 sites in northeastern China. According to the climate data from 1950 to 2014, we determined three extreme drought years (1954, 1967, and 2008). The response difference of radial growth of trees and shrubs in boreal forests to drought was compared using resilience index, moving correlation and response analysis. The results showed that high temperature (mean and maximum temperature) in previous and current growing seasons promoted the growth of P. pumila, but inhibited the growth of trees. On the contrary, wetter conditions (higher PDSI) promoted tree growth but were not conducive to P. pumila growth in high latitudes. Moving correlation analysis showed similar results. In addition, water deficit was more likely to inhibit P. pumila growth in low latitudes. The drought resistance of P. pumila was stronger than that of L. gmelinii and P. sylvestris var. mongolica. Therefore, the growth loss and recovery time of P. pumila during drought was less than those of trees. We concluded that L. gmelinii and P. sylvestris var. mongolica are more prone to growth decline than P. pumila after the drought caused by climate warming. In the future climate warming, shrub growth may benefit more than trees. Our findings are of great significance in predicting the future changes in ecosystem composition and species distribution dynamics in extreme climate susceptible areas.

Changes of non-structural carbohydrates and nitrogen contents of needles and twigs in Pinus sylvestris var. mongolica plantations along an aridity gradient

With six Pinus sylvestris var. mongolica plantations (Huinan, Xifeng, Fujia, Zhanggutai, Naiman and Wulanaodu) along an aridity gradient in the Horqin sandy land, we examined the changes in non-structural carbohydrates (NSCs) and nitrogen (N) contents of current and one-year-old needles and twigs, to explore the carbon supply and demand status as well as the nutrient accumulation strategies of P. sylvestris var. mongolica under drought. The results showed that the contents of NSCs and soluble sugars in needles and twigs of P. sylvestris var. mongolica plantations significantly decreased with increasing aridity. From the most humid site (Huinan) to the most aridity site (Wulanaodu), the soluble sugar contents in current and one-year old needles of P. sylvestris var. mongolica decreased from 12.8% and 12.5% to 9.0% and 9.5%, respectively. The soluble sugar contents in current-year old twigs decreased from 15.6% to 9.2%. With increasing aridity, the starch contents in needles and twigs remained relatively stable, soluble sugars/starch ratio in current and one-year old needles decreased, the N contents in current and one-year old twigs significantly increased. The P. sylvestris var. mongolica plantations in the Horqin sandy land consumed soluble sugar storage under drought, resulting in a risk of mortality from 'carbon starvation'. P. sylvestris var. mongolica tended to maintain stable starch storage and accumulate N in twigs to cope with long-term drought stress.

Key Strategies Underlying the Adaptation of Mongolian Scots Pine (Pinussylvestris var. mongolica) in Sandy Land under Climate Change: A Review

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.

Effects of Mixed Decomposition of Pinus sylvestris var. mongolica and Morus alba Litter on Microbial Diversity.

Pinus sylvestris var. mongolica is widely planted in China as a windbreak and sand fixation tree. To improve the current situation of large-scale declines of forested areas planted as P. sylvestris var. mongolica monocultures, we investigated the biological and microbial effects of stand establishment using mixed tree species. The interactions during the mixed decomposition of the litter and leaves of different tree species are an important indicator in determining the relationships among species. In this experiment, a method of simulating the mixed decomposition of P. sylvestris var. mongolica and Morus alba litter under P. sylvestris var. mongolica forest was used to determine the total C, total N, and total P contents in the leaf litter, and the microbial structures were determined by using Illumina MiSeq high-throughput sequencing. It was found that with samples with different proportions of P. sylvestris var. mongolica and M. alba litters, the decomposition rate of P. sylvestris var. mongolica × M. alba litter was significantly higher than that of the pure P. sylvestris var. mongolica forest, and the microbial community and composition diversity of litter in a pure P. sylvestris var. mongolica forest could be significantly improved. The possibility of using M. alba as a mixed tree species to address the declines of pure P. sylvestris var. mongolica forest was verified to provide guidance for pure P. sylvestris var. mongolica forests by introducing tree species with coordinated interspecific relationships and creating a mixed forest.

Superhydrophobic wood fabricated by epoxy/Cu2(OH)3Cl NPs/stearic acid with performance of desirable self-cleaning, anti-mold, dimensional stability, mechanical and chemical durability

Pinus wood (Pinus sylvestris var. mongolica Litv.) was modified to make it superhydrophobic by a simple hydrothermal method for in-situ synthesis Cu2(OH)3Cl nanoparticles (NPs) followed by impregnation with a stearic acid/epoxy resin (STA/EP) ethanol solution. Surface microstructure, roughness and chemical constituents of the modified wood were characterized by scanning electron microscopy (SEM), 3D confocal microscope profilometry, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Modified wood exhibited superhydrophobicity, characterized by a static water contact angle (WCA) reach 151 ± 3° and sliding angle (SA) less than 6 ± 3°. The modified wood remained superhydrophobicity under harsh conditions including impregnation with strong acid or alkali, 7 cycles of sandpaper abrasion, 200 cycles of tape paste, 192 h of UV irradiation and exposed at 140 °C. The modified wood also exhibited excellent functions, including anti-mold, dimensional stability, stain resistance and self-cleaning, which suggested that the process has potential for protecting wood in exterior exposures.

Roseococcus pinisoli sp. nov., lacking pufL and pufM bacteriochlorophyll a: synthesizing genes.

A Gram-stain-negative, cocci-to-oval-shaped bacterial strain, designated XZZS9T, was isolated from the rhizosphere soil of Pinus sylvestris var. mongolica and characterized taxonomically using a polyphasic approach. Growth occurred at 20-35°C (optimum, 28°C), pH 6.0-11.0 (optimum, pH 7.0), and in 0-1% NaCl (optimum, 0%). Phylogenetic analysis based on 16S rRNA gene sequencing indicated that strain XZZS9T was related to members of the genus Roseococcus, with the highest sequence identity to Roseococcus microcysteis NIBR12T (96.9%). The major cellular fatty acids (> 5% of the total) were C18:1 ω7c and C19:0 cyclo ω8c. The major isoprenoid quinone was Q-9 and the polar lipid profile contained diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, an unidentified glycophospholipid, and an unidentified phospholipid. Genome sequencing revealed that had a genome size of 4.79 Mbp with a G + C content of 69.5%. Comparative genomic analyses clearly separated strain XZZS9T from the known species of the genus Roseococcus based on average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values below the thresholds for species delineation. Genome annotations did not find pufL and pufM genes in strain XZZS9T, suggesting a possible lack of photosynthetic reaction. Based on genotypic and phenotypic characteristics, strain XZZS9T represents a novel species of the genus Roseococcus, for which we propose the name Roseococcus pinisoli sp. nov. The type strain is XZZS9T (= KCTC 82435T = JCM 34402T = GDMCC 1.2158T).