Larix Principis-rupprechtii Research Articles

Structural Equation Modeling of Phosphorus Transformations in Soils of Larix principis-rupprechtii Mayr. Plantations

Understanding the soil phosphorus (P) cycle is a prerequisite for the sustainable management of land resources. The sequential-extraction method was used to determine P fractions in 513 soils of Larix principis-rupprechtii Mayr. plantations. With these data, this study applied structural equation modeling to evaluate the interaction between various soil P fractions. Quantitative analysis was conducted on the importance of different soil P pools and P transformation pathways on soil P availability in a larch plantation. Our study showed that soluble inorganic P (Pi) was directly positively affected by labile Pi, labile organic P (Po), secondary mineral P, and primary mineral P, and was directly negatively affected by moderately labile Po. Soluble Pi was not directly affected by occluded P. The primary mineral P (β = 0.40) had the greatest total impact on soluble Pi, followed by secondary mineral P (β = 0.32) and labile P (labile Pi and Po, β = 0.31), and then occluded P (β = 0.11), with the total impact of moderately labile Po being relatively small (β = −0.06). In summary, this study reveals the important roles of soluble Pi in P transformations and in determining overall P availability in soils, as well as the extensive effects of weathering on soil P dynamics in L. principis-rupprechtii plantations.

Drivers of vegetation and soil determine natural regeneration of a single plantation at different slope positions

Promoting natural regeneration in artificial forest ecosystems is crucial for sustainable management. Understanding the fundamental mechanisms and drivers of tree regeneration is the prerequisite for promoting it effectively. This study worked with Larix principis-rupprechtii, a species considered difficult to regenerate. Twenty-four sample plots measuring 30 m × 30 m were established, with eight plots at each of the lower, middle, and upper slope positions, respectively. Field investigation and multivariate analysis were performed to uncover the regeneration traits in the plantations with abundant seedlings on the continuous slope. The results revealed that ground diameter and height of the regeneration (RGD and RH) were larger at the lower slope, with significant positive correlations to available nitrogen (contribution rate, CR: 0.858) and slope (CR: 0.652). In contrast, regeneration density (RD), representing the quantity of regeneration, was greater at the middle slope. Its significant impact factors were slope position (CR: −0.648) and herb diversity, represented by Pielou index (CR: 0.961). Stand density had a significant negative effect on regeneration, particularly at the upper slope, with CRs of −0.842 and −0.764 to RGD/RH and RD, respectively. Common contribution was found among the factors, with the largest contribution groups being the topographical and soil factors (CR: 0.358). These findings provide valuable insights into the single species regeneration progress on northern mountainous slopes and offer essential information for developing facilitation methods for the natural regeneration in artificial forests.

Antifreeze Evaluation of Two Dehydrin Proteins from Pseudotsuga menziesii and Larix principis-rupprechtii Mayr

Dehydrins exist widely in plants and play an important role in abiotic stress resistance. Two low-temperature-induced dehydrin-like genes, PmCAP and LpCAP, from the pine species Pseudotsuga menziesii and Larix principis-rupprechtii Mayr were cloned and found to contain 576 bp and 687 bp, encoding 191 and 228 amino acids, respectively. Both genes were individually assembled into prokaryotic expression vectors and transferred into E. coli cells. When transgenic stains were cultured at −5 °C, the lethal time 50% (LT50) was 50 h and 54 h for PmCAP and LpCAP, respectively, compared with 32 h for the control. When cultured at −20 °C, the LT50 was 38 h, 41 h, and 25 h for PmCAP, LpCAP, and the control. Thermal hysteresis (TH) testing of PmCAP and LpCAP proteins revealed TH values of 0.27 °C and 0.72 °C, respectively, relative to 0.05 °C for the BSA control. These results indicate that the two pine dehydrin proteins have antifreeze characteristics and that their antifreeze levels were well in relation to the environmental conditions of pine growth (Larix principis-rupprechtii Mayr mostly grows in cold and high-altitude zones, while Pseudotsuga menziesii grows in temperate and low-altitude zones). LpCAP, especially, could be a better gene resource for the molecular breeding of plant cold resistance.

Soil Microbial Community, Soil Quality, and Productivity along a Chronosequence of Larix principis-rupprechtii Forests.

Elucidating the correlation between soil microbial communities and forest productivity is the focus of research in the field of forest ecology. Nonetheless, the relationship between stand age, soil quality, soil microorganisms, and their combined influence on productivity is still unclear. In this study, five development stages (14, 25, 31, 39, and >80 years) of larch (Larix principis-rupprechtii) forests were investigated in Inner Mongolia and Shanxi provinces of China. We evaluated soil quality using the Integrated Soil Quality Index (SQI) and analyzed changes in bacterial and fungal communities using high-throughput sequencing. Regression models were also established to examine the impacts of stand age, microbial diversity, and SQI on productivity. The findings revealed an ascending trend in soil organic matter (SOM), total nitrogen (TN), total phosphorus (TP), available potassium (AK), and SQI in 14, 25, 31, and 39-year-old stands. The abundance of oligotrophic bacteria Acidobacteria exhibited a gradual decline with increasing forest age, whereas copiotroph bacteria Proteobacteria displayed a progressive increase. Stands older than 80 years exhibited a higher abundance of both the saprophytic fungus Ascomycota and mycorrhizal fungus Basidiomycota. Forest age had a significant impact on microbial diversity, particularly in terms of bacterial diversity, impacting both α and β diversity. The soil bacterial community structure was influenced by AK, SOM, TN, TP, and pH. Conversely, the fungal community structure was regulated by crucial factors including SOM, TN, TP, TK, AK, and pH. Fungal diversity demonstrated a significant and positive correlation with the basal area increment (BAI) of larch. Furthermore, microbial diversity accounted for 23.6% of the variation in BAI. In summary, the findings implied a robust association between microbial composition, diversity, and soil chemical properties throughout the chronosequence of larch forests. These factors collectively played a crucial role in influencing the productivity of larch forest.

Potential factors promoting the natural regeneration of Larix principis-rupprechtii in North China.

Natural regeneration plays an important role in species diversity and evolution. Exploring the causes of variation in regeneration dynamics can provide key insights into the factors affecting regeneration. However, the relationship between the regeneration of Larix principis-rupprechtii and environmental factors in North China has remained unexplored. In this study, 14 plots were established based on the three extents of regenerated plant numbers in Shanxi Province. Redundancy analysis determined that environmental factors (topography, stand structure, soil property, and litter) affected natural regeneration. Structural equation modeling identified the most important direct and indirect factors that affected L. principis-rupprechtii natural regeneration. Litter thickness, canopy density, and adult tree diameter at breast height were positively correlated with natural regeneration. Aspect and total nitrogen volume were negatively associated with natural regeneration. Additionally, there was no significant correlation between natural regeneration and other environmental factors (altitude, slope, adult tree height, stand density, soil water content, SOC, total P, available N, available P, or soil enzyme). Further artificial intervention measures should be considered to promote plantation regeneration. These findings provide an effective basis for future forest restorations and sustainable management.

Differences in ecological resilience of radial growth between Larix principis-rupprechtii and Picea meyeri after drought.

To understand the responses of radial growth to climatic factors and the differences in ecological resilience to drought between a heliophilous species Larix principis-rupprechtii and a shade species Picea meyeri in mixed forests, we developed the tree-ring width chronologies of L. principis-rupprechtii and P. meyeri in three mixed forests based on the samples collected from Toudaogou of Saihanba in Hebei, Ningwu County and Kelan County in Shanxi Province. We analyzed the correlation between climatic factors and various chronologies and examined the differences in resistance (Rc), recovery (Rt), and resilience (Rs) of L. principis-rupprechtii and P. meyeri in response to drought stress. The results showed that the radial growth of L. principis-rupprechtii and P. meyeri was negatively correlated with the mean and maximum air temperature from May to July in three mixed forests, and was positively correlated with the Palmer drought index (PDSI) from May to September. Radial growth decline in trees due to drought stress was significantly different between the two species among the three sites, indicating different physiological and ecological regulation strategies. The resistance of P. meyeri was stronger than that of L. principis-rupprechtii at the three study sites, with stronger resilience and resilient elasticity of L. principis-rupprechtii than P. meyeri. As a result, P. meyeri exhibited greater drought resistance than L. principis-rupprechtii. Under global warming condition, L. principis-rupprechtii might be at greater risk of growth decline than P. meyeri in this region.

Distribution Pattern of Bacterial Community in Soil Profile of Larix principis-rupprechtii Forest in Luya Mountain

Microbial communities are the key component to maintaining the structure and function of forest soil ecosystems. The vertical distribution of bacterial communities on the soil profile has an important impact on forest soil carbon pools and soil nutrient cycling. Using Illumina MiSeq high-throughput sequencing technology, we analyzed the characteristics of bacterial communities in the humus layer and 0-80 cm soil layer of Larix principis-rupprechtii in Luya Mountain, China, to explore the driving mechanisms affecting the structure of bacterial communities in soil profiles. The results showed that the α diversity of bacterial communities decreased significantly with increasing soil depth, and community structure differed significantly across soil profiles. The relative abundance of Actinobacteria and Proteobacteria decreased with increased soil depth, whereas the relative abundance of Acidobacteria and Chloroflexi increased with the increase in soil depth. The results of RDA analysis showed that soil NH+4, TC, TS, WCS, pH, NO-3, and TP were important factors determining the bacterial community structure of the soil profile, among which soil pH had the most significant effect. Molecular ecological network analysis showed that the complexity of bacterial communities in the litter layer and subsurface soil (10-20 cm) was relatively high, whereas the complexity of bacterial communities in deep soil (40-80 cm) was relatively low. Proteobacteria, Acidobacteria, Chloroflexi, and Actinobacteria played important roles in the structure and stability of soil bacterial communities in Larch. The species function prediction of Tax4Fun showed a gradual decline in microbial metabolic capacity along the soil profile. In conclusion, soil bacterial community structure showed a certain distribution pattern along the vertical profile of soil, the community complexity gradually decreased, and the unique bacterial groups of deep soil and surface soil were significantly different.

Aridity index and quantile regression influences on the maximum size-density relationship for coniferous and broad-leaved mixed forests

The maximum size-density relationship (MSDR) of mixed stands is of great significance for optimizing stand structural components and increasing stand productivity. However, model structure, climatic factors and parameter estimation methods affect the prediction accuracy of MSDR for multi-species mixed stands with complex structures, emphasizing the need to improve MSDR prediction methods. This study applied likelihood analysis to 333 sample plots of larch (Larix principis-rupprechtii Mayr.) and birch (Betula platyphylla Suk.) coniferous and broad-leaved mixed forests in Saihanba, Hebei Province, China to determine the structure of MSDR. Nonlinear least squares and nonlinear quantile regression were used to construct the MSDR of mixed stands, including the Martonne aridity index (M) which is a composite index that responds to temperature and precipitation. The results indicate that the optimal model form for predicting the MSDR of mixed stands is a nonlinear additive error structure. When considering M and using a quantile q = 0.95, the MSDR can accurately describe the variation in stand density of mixed larch-birch coniferous and broad-leaved forests.

Effect of thinning intensity on natural regeneration of Larix principis-rupprechtii.

We analyzed the impacts of thinning intensity on the natural regeneration of Larix principis-rupprechtii in Shanxi Pangquangou Nature Reserve, with an experiment of five thinning intensities (5%, 25%, 45%, 65% and 85%). We constructed a structural equation model of thinning intensity-understory habitat-natural regeneration by using correlation analysis. The results showed that the regeneration index of moderate thinning (45%) and intensive thinning (85%) stand land was significantly higher than that of other thinning intensities. The constructed structural equation model had good adaptability. The effects of thinning intensity on each factor were as follows: soil alkali-hydrolyzable (-0.564) > regeneration index (0.548) > soil bulk density (-0.462) > average height of seed tree (-0.348) > herb coverage (-0.343) > soil organic matter (0.173) > undecomposed litter layer thickness (-0.146) > total soil nitrogen (0.110). Thinning intensity had a positive impact on the regeneration index, which was mainly through adjusting height of the seed tree, accelerating litter decomposition, improving soil physical and chemical properties, and thus indirectly promoting the natural regeneration of L. principis-rupprechtii. Tending thinning could effectively improve the survival environment of regeneration seedlings. From the perspective of natural regeneration of L. principis-rupprechtii, moderate thinning (45%) and intensive thinning (85%) were more reasonable in the follow-up forest management.

EVOLUTION AND DISTRIBUTION OF SHAKES IN LARCH LOGS DURING AIR DRYING

This paper analyzed the length, width, and location of shakes in the air-drying process of larch log (Larix principis-rupprechtii Mayr) 1 m long and 66% initial moisture content. The development law and distribution characteristics of shakes during log drying of larch were studied and shake generation and development law were analyzed from two aspects of microstructure and growth defects. The variation of dry shrinkage deformation along the radial direction and knot influence on it was analyzed using the split-shaped stress test strips. At the cellular level, the cell wall shrinkage behavior of heartwood and sapwood and the microstructure of knots were observed. The results showed a significant relationship between eccentricity and shake distribution; the IIa region is the most prone to dry shake. The evolution of shakes is closely related to the drying rate. In the high-speed drying stage (MC ≥ 40%), shakes almost do not occur; in the decelerating drying stage (40% ≥ MC ≥ 20%), the amount, length, and width of shakes increase rapidly. In the low-speed drying stage (20% ≥MC), the area of shakes tends to stabilize or even decline. The main reasons for dry shaking are the dry shrinkage difference between tangential and radial cell walls, early and late wood, heartwood and sapwood, and moisture content gradient during the drying process.

Dynamics of soil net nitrogen mineralization and controlled effect of microbial functional genes in the restoration of cold temperate forests

Soil nitrogen mineralization (Nmin) generally controls the availability and circulation of soil nitrogen (N). To better understand the mechanisms of soil Nmin and environmental protection, this study explored the dynamics of net Nmin in soils from restored forests and the effect of soil physicochemical properties (SPPs) and soil microbial mineralization genes (SMGs) on Nmin. Field studies were conducted from July 2019 to April 2020 in five representative restored forests in the mountainous region of northwestern Hebei, China (i.e., Larix principis-rupprechtii forest (LF), Betula platyphylla forest (BF), mixed forest of Larix principis-rupprechtii and Betula platyphylla (MF), Picea asperata forest (SF) and Pinus sylvestris var. mongolica forest (MPF)), and soil net nitrogen mineralization rate (Rmin), SPPs and SMGs were determined after collecting soil samples in five plots. The influence of restored forests and seasonality on Rmin was investigated to determine the characteristics of the dynamics of soil net Nmin. Principal component analysis (PCA) and variation partitioning analysis (VPA) revealed that soil properties and functional genes could explain approximately 80 % of the variation in Nmin. SMGs significantly contributed to the variation in the soil net ammonification rate (Ramm) and nitrification rate (Rnit) compared to soil properties. SMGs were strongly correlated with Ramm\\Rnit (except in LF), implying that the shifts in functional genes may control Rmin. Given the debate on the role of soil properties and N cycling genes in driving soil N transformation, this study provides new insights into the controlled effect of microbial functional genes during the early stage of forest restoration in the cold temperate zone.

Deterioration of Microstructures and Properties in Ancient Architectural Wood from Yingxian Wooden Pagoda (1056 AD) during Natural Aging

The Yingxian Wooden Pagoda (1056 AD), located in Shanxi province, China, is a unique architectural pure-wooden artifact standing for a millennium. Despite its longevity, the structures and properties of the ancient architectural woods used in its construction have been significantly degraded due to long-term natural aging, which has profoundly impacted the preservation of this valuable cultural heritage. To better understand this degradation, we studied the deterioration of a baluster (Larix principis-rupprechtii Mayr.) from Yingxian Wooden Pagoda. The study employed various analytical techniques, including optical microscopy, atomic force microscopy, Fourier-transform infrared spectroscopy, solid-state 13C nuclear magnetic resonance spectroscopy, X-ray diffraction, and nanoindentation technology, to evaluate the microstructures and properties of the ancient architectural woods. Results indicated that the destruction of wood cell walls was primarily transverse transwall destruction and interfacial debonding and that the degradation of chemical components was primarily in the hemicellulose (xylan) and amorphous region of cellulose. The reduced elastic modulus and hardness of tracheid cell walls in the ancient architectural woods were higher than in recent larch woods. This study would help deepen understanding of wood deterioration during long-term natural aging for the subsequent preservation and protection of wooden cultural heritages and longer use of ancient timber constructions.

Effects of Environmental Factors on the Nonstructural Carbohydrates in Larix principis-rupprechtii

Nonstructural carbohydrates (NSCs) reflect the carbon balance in trees and play a central role in their responses to environmental stresses. However, our understanding of tree NSC storage dynamics under environmental stress is unclear. Here, we quantified the deciduous conifer Larix principis-rupprechtii at five altitudes on Luya Mountain, North-Central China. We measured NSCs in different organs and simultaneously monitored environmental variables during the growing seasons in 2018 and 2019. The results showed that temperature was the main environmental factor affecting tree NSCs. Furthermore, as the soil–atmosphere temperature gradient decreased, the concentrations of soluble sugars in the needles increased while their starch decreased, as well as the concentrations of starch in the shoots, stems, and roots increased. These results may indicate that temperature gradients may assist carbohydrate allocation within individual trees. The NSCs, especially starch, in the needles increased with lower soil moisture, and the soluble sugars and starch in the needles and shoots increased with a higher vapor pressure deficit. The soluble sugars in the stems were significantly affected by soil moisture, and the NSCs in the roots were mainly affected by temperature. These results provide new insights to improve our understanding of the environmental stress effects on future forest C balances.

Predicting the growth suitability of Larix principis-rupprechtii Mayr based on site index under different climatic scenarios.

Larix principis-rupprechtii Mayr (larch) is one of the main afforestation and timber production species used in North China. Climate change has led to a change in its suitable distribution and growth. However, the impact of climate change on its growth suitability is not clear. In this study, using forest resource inventory data and spatially continuous environmental factor data (temperature, precipitation, topography, and soil) in Hebei and Shanxi Provinces, China, the random forest model (RF) was used to simulate the larch site index (SI) and growth suitability under three shared socioeconomic pathways (SSPs: SSP1-2.6, SSP2-4.5, and SSP5-8.5) for the current and future (2021-2040, 2041-2060 and 2080-2100). The results revealed that (1) RF had excellent performance in predicting the regional SI (R2 = 0.73, MAE = 0.93m, RMSE = 1.35m); (2) the main factors affecting the productivity of larch were the mean temperature of the warmest quarter (BIO10), elevation (ELEV), mean diurnal range (BIO2), and annual precipitation (BIO12); and (3) larch currently had a higher SI in the Bashang areas and in the high-altitude mountains. The areas characterized as unsuitable, poorly suitable, moderately suitable, and highly suitable accounted for 15.45%, 42.12%, 31.94%, and 10.49% of the total area, respectively. (4) Future climate warming had an obvious inhibitory effect on the SI, and the effect strengthened with increasing radiation intensity and year. (5) The moderately suitable and highly suitable areas of larch growth showed a downward trend under future climate scenarios. By the end of this century, the suitable growth areas would decrease by 14.14% under SSP1-2.6, 15.17% under SSP2-4.5, and 19.35% under SSP5-8.5. The results revealed the impact of climate change on larch growth suitability, which can provide a scientific basis for larch forest management.

Biochar catalysts for efficiently 5-Hydroxymethylfurfural (HMF) synthesis in aqueous natural deep eutectic solvent (A-NADES)

This study prepared a series of biochar-based catalysts using different parts of Larix principis-rupprechtii as feedstock, to promote the 5-Hydroxymethylfurfural (HMF) synthesis from glucose and fructose. Sulfonated biochar showed high converting efficiency of fructose in both dimethyl sulfoxide (DMSO) and aqueous-natural deep eutectic solvent (A-NADES) reaction systems, with HMF yield of 96.3% prepared from the pine needle-derived acidic catalyst under mild condition. Bifunctional acidic biochar catalysts containing both Lewis acid and Brønsted acid functional groups could effectively enhance the glucose conversion with 57.2% of the HMF yield obtained in A-NADES. After the detailed characterization of the biochar catalysts, the potential mechanism of the bifunctional catalyst for the synthesis of HMF by conversion of glucose and fructose was proposed. The possible promoting mechanism of carbohydrate conversion by A-NADES through intermolecular hydrogen bonding was also explored.

Biomass allometric models for Larix rupprechtii based on Kosak's taper curve equations and nonlinear seemingly unrelated regression.

The diameter at breast height (DBH) is the most important independent variable in biomass allometry models based on metabolic scaling theory (MST) or geometric theory. However, the fixed position DBH can be misleading in its use of universal scaling laws and lead to some deviation for the biomass model. Therefore, it is still an urgent scientific problem to build a high-precision biomass model system. A dataset of 114 trees was destructively sampled to obtain dry biomass components, including stems, branches, and foliage, and taper measurements to explore the applicability of biomass components to allometric scaling laws and develop a new system of additive models with the diameter in relative height (DRH) for each component of a Larch (Larix principis-rupprechtii Mayr) plantation in northern China. The variable exponential taper equations were modelled using nonlinear regression. In addition, applying nonlinear regression and nonlinear seemingly unrelated regression (NSUR) enabled the development of biomass allometric models and the system of additive models with DRH for each component. The results showed that the Kozak's (II) 2004 variable exponential taper equation could accurately describe the stem shape and diameter in any height of stem. When the diameters in relative height were D0.2, D0.5, and D0.5 for branches, stems, and foliage, respectively, the allometric exponent of the stems and branches was the closest to the scaling relations predicted by the MST, and the allometric exponent of foliage was the most closely related to the scaling relations predicted by geometry theory. Compared with the nonlinear regression, the parameters of biomass components estimated by NSUR were lower, and it was close to the theoretical value and the most precise at forecasting. In the study of biomass process modelling, utilizing the DRH by a variable exponential taper equation can confirm the general biological significance more than the DBH of a fixed position.

不同时间尺度下华北落叶松人工林冠层蒸腾与环境因子的关系

PDF HTML阅读 XML下载 导出引用 引用提醒 不同时间尺度下华北落叶松人工林冠层蒸腾与环境因子的关系 DOI: 10.5846/stxb202107151903 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 内蒙古自治区关键技术攻关计划项目(2021GG0033);内蒙古自治区林业和草原局科研能力提升项目;内蒙古自治区自然科学基金项目(2021MS03101) Relationship between canopy transpiration of larch plantation and environmental factors at different time scales Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:在半干旱区连续2年监测华北落叶松(Larix principis-rupprechtii)的树干液流、气象因子和土壤体积含水量,分析不同时间尺度下人工林冠层蒸腾与环境因子的关系。结果表明:不同时间尺度下,华北落叶松人工林冠层蒸腾的季节变化均呈单峰曲线,即先增大后减小的趋势;2016年、2017年日蒸腾量分别为1.58 mm/d和1.71 mm/d,生长季蒸腾总量分别为241.30 mm和260.97 mm。在日尺度下,气温、太阳辐射强度和饱和水汽压差是影响华北落叶松人工林冠层蒸腾主要环境因子;月尺度下,气温、风速、降水和土壤水分是冠层蒸腾的主要影响因子;冠层蒸腾与降水、大气相对湿度的相关关系由日尺度下的负相关到月尺度的正相关,相关性增强。总体来看,随时间尺度由小到大,气温、风速、大气相对湿度、降水、土壤水分对冠层蒸腾的影响作用增大,而太阳辐射强度、饱和水汽压差的作用减弱;在未来增温增雨趋势下,研究区生长季将延长,华北落叶松人工林冠层蒸腾量可能会加大。 Abstract:Canopy transpiration is a major part of forestland water balance and a fundamental datum in understanding the planted forest ecophysiology in dry regions. Quantitatively analyzing variation of canopy transpiration induced by the environmental factors is beneficial for a better estimation forestland water balance and prediction the plantation ecophysiology. But the response mechanism of canopy transpiration to environmental factors may be different in different time scales, so it needs to be further understood. This study was conducted in a 42-year-old Larix principis-Rupprechtii plantation (a density of 1933 trees/hm2) at the middle position of a north facing slope in the Inner Mongolian Daqingshan National Nature Reserve, a semi-arid region of China. Firstly, the sap flow velocity in ten healthy and dominant Larix principis-Rupprechtii trees, soil volumetric water content and meteorological factors including air temperature, precipitation, solar radiation intensity, air relative humidity and wind speed, were observed during two growing seasons (May 1 to September 30) in 2016 and 2017 which precipitation was 435.00 mm and 348.80 mm, respectively. Then, sap flow velocity values which was measured by the thermal diffusion method, were upscaled to the forest canopy level. Finally, the relationship between canopy transpiration and the environmental factors at different time scales was analyzed. The results showed that the seasonal changes of canopy transpiration showed a single peak curve under the different time scales, that was, the trend of increase first and then decrease. In 2016 and 2017, the average value of daily canopy-level transpiration was 1.58 mm/d and 1.71 mm/d, respectively, and the total transpiration in the growing season was 241.30 mm and 260.97 mm, respectively. On the daily scale, air temperature, solar radiation intensity and saturated vapor pressure deficit markedly affected canopy transpiration. At the monthly scale, air temperature, wind speed, precipitation and soil volumetric water content were the main influencing factors of canopy transpiration. The correlation between transpiration and precipitation and air relative humidity increased from negative correlation on the daily scale to positive correlation on the monthly scale. In general, with time scale from small to large, the effects of air temperature, wind speed, air relative humidity, precipitation and soil water content on canopy transpiration increase, while the effects of solar radiation intensity and saturated vapor pressure deficit decrease. With the trend of increasing temperature and rainfall in the future, the growing season of Larix principis-Rupprechtii in the study area will be prolonged, and the canopy transpiration may increase. 参考文献 相似文献 引证文献

气候变化对北京常见树种春季萌芽的影响——基于控制实验研究

PDF HTML阅读 XML下载 导出引用 引用提醒 气候变化对北京常见树种春季萌芽的影响——基于控制实验研究 DOI: 10.5846/stxb202112183591 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家杰出青年基金项目（42025101）；高等学校学科创新引智计划项目（B18006） Effects of climate change on spring budburst of typical tree species in Beijing based on manipulative experiments Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:气候变化对植物物候产生了重要影响，春季萌芽时间的变化不仅会通过改变植物的光合作用影响碳汇能力，还会通过改变群落内的种间关系影响生态系统结构和功能。因此，掌握群落内不同树种春季萌芽对气候变化的响应对于深刻理解物候时间位分化、认识陆地生态系统碳水循环和能量平衡具有重要意义。为提高春季物候模型的预测精度，阐明气候变化对不同树种春季萌芽的影响，以鹅耳枥（Carpinus turczaninowii）、黑桦（Betula dahurica）、华北落叶松（Larix principis-rupprechtii）、糠椴（Tilia mandshurica）和元宝枫（Acer truncatum）5个温带森林的典型树种为研究对象，通过剪枝实验分析了冬季冷激、春季温度和光周期对枝条春季萌芽时间的影响。结果表明，温度升高和冷激增加显著提前了所有树种的春季萌芽时间，从5℃到20℃，春季萌芽时间平均提前了54.5 d；在较高的冷激条件下，春季萌芽时间平均缩短了17.8 d；光周期对各树种春季萌芽时间均没有显著影响，8 h和16 h光周期条件下各树种平均萌芽时间分别为30.3和30.5 d。此外，随着温度升高，5个树种萌芽时间间隔显著缩短，这主要是由于温度升高萌芽热量需求降低导致的，冷激对树种间萌芽时间间隔无显著影响。在气候变暖背景下，森林群落中不同树种萌芽时间间隔将显著缩短，进而影响物候时间生态位分化，导致种间竞争加剧。研究阐明了气候变化对温带阔叶树种春季萌芽及其时间间隔的影响，为气候变化条件下森林生态系统群落动态及森林可持续经营与管理策略的制定提供了理论支撑。 Abstract:Climate change has caused substantial effects on plant phenology over the past decades. Shifts in spring budburst not only affect carbon sink capacity by changing plants' photosynthesis but also influence the structure and function of the ecosystem by altering the relationship between species within the forest community. Understanding how spring budburst of different species respond to climate change is thus essential to improve our knowledge of phenological temporal niche differentiation, carbon and water cycles, as well as the energy balance of terrestrial ecosystems. In order to improve the ability of the spring phenology model and the influence underlying the responses of spring budburst to climate change, we selected five typical temperate tree species in Beijing, i.e. Carpinus turczaninowii, Betula dahurica, Larix principis-rupprechtii, Tilia mandshurica, and Acer truncatum, to test the effects of winter chilling, spring temperature and photoperiod on spring budburst by using twig cutting experiment. We found that photoperiod had no significant effect on spring budburst while increasing spring temperature and winter chilling significantly advanced budburst date. From 5℃ to 20℃, the budburst was advanced by 54.5 days on average, and it was shortened under high chilling conditions by about 17.8 days. The photoperiod had no significant effect on the budburst of each tree species. The average budburst of tree species was 30.3 and 30.5 days under the condition of 8 hours and 16 hours of photoperiod, respectively. In addition, the time interval of budburst between the five tree species was significantly shortened with the spring warming, which might be caused by the heating requirements of budburst under different temperature treatments, which was mainly caused by the decrease of heat requirement for budburst with the increase of temperature, and the chilling had no significant effect on their time interval. Under the background of climate change, the budburst and time interval of budburst between tree species is likely to largely shorten, which would change the differentiation of temporal niche, leading to the increased inter-species competition. This study clarifies the impact of climate change on the budburst and time interval of temperate broad-leaved tree species and provides theoretical support for the formulation of forest ecosystem community dynamics and forest sustainable operation and management strategies under the condition of climate change. 参考文献 相似文献 引证文献

Growth Suitability Evaluation of Larix principis-rupprechtii Mayr Based on Potential NPP under Different Climate Scenarios

Larch (Larix principis-rupprechtii Mayr) is a major coniferous tree species in northern China, and climate change has serious impacts on larch growth. However, the impact of future climate change on net primary productivity (NPP) and the growth suitability of larch is unclear. Based on forest inventory data, spatially continuous environmental factor data (climate, topography, soil), and NPP from the Carnegie-Ames-Stanford approach (CASA) model in the study area, the random forest (RF) model was used to simulate the potential NPP and growth suitability of larch under different shared socioeconomic pathways (SSP1-2.6, SSP2-4.5, SSP3-7.0, SSP5-8.5) for current and future (2041–2060, 2080–2100). The correlation between potential NPP and determinants under different climate scenarios was analyzed at the pixel scale. The results showed that: (1) RF showed excellent performance in predicting the potential NPP of the region (R2 = 0.80, MAE = 15.61 gC·m−2·a−1, RMSE = 29.68 gC·m−2·a−1). (2) Under current climatic conditions, the mean potential NPP of larch was 324.9 gC·m−2·a−1. Low growth suitability of larch occurred in most parts of the study area, and high growth suitability only existed in the Bashang area and the high-elevation mountains. (3) The total area of high and medium growth suitable areas were projected to be 76.0%, 66.7%, 78.2%, and 80.8% by the end of this century under the SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5 climate scenarios, respectively. (4) Under the SSP1-2.6 and SSP2-4.5 climate scenarios, the temperature had a significant contribution to the accumulation of the larch’s NPP, whereas precipitation had less effect on the larch’s growth. The results provided a theoretical basis for the adaptive management of larch forests under global climate change.

Effects of natural ageing on macroscopic physical and mechanical properties, chemical components and microscopic cell wall structure of ancient timber members

The main objective of this study was to investigate the effects of natural ageing on macroscopic physical and mechanical properties, chemical components, and microscopic cell wall structure of larch (Larix principis-rupprechtii Mayr) and nanmu (Phoebe zhennan S. Lee) timber members in ancient architecture. In this work, aged larch and nanmu timber members were obtained from the restoration architecture and their ages were determined based on accelerated mass spectrometer 14C method. Macroscopic physical, mechanical properties and chemical components were tested and determined of each timber members; meanwhile, the microstructural changes of cell wall were observed by scanning electron microscope (SEM). Finally, Pearson’s correlation analysis was conducted to reveal the relationships among them. The results indicated that natural ageing has a significantly effect on the macroscopic physical and mechanical properties, chemical components, and microscopic cell wall structure. First, equilibrium moisture content (EMC), the coefficient of wet swelling coefficient (SW) and colour parameters considerably changed of larch and nanmu timber members with aging years. Mechanical property parameters of larch timber show a significant decrease, and the changes of chemical components and microstructure of cell structure of nanmu specimens indicates the mechanical property parameters decreased. Further, the relative contents of cellulose and hemicellulose were significantly reduced, obvious damage and deformation were observed in the cell wall of larch and nanmu timber specimens. The results explained the change of macroscopic physical and mechanical properties, especially negative effects on mechanical properties. It was concluded that the relative contents of cellulose and hemicellulose were decreased, and the microstructure was damaged under the natural ageing effect, resulting in a decrease in mechanical properties with an increase in colour properties and dimensional stability.