Broad-leaved Korean Pine Mixed Forest Research Articles

Scale-dependent effects of vegetation attributes and soil fertility on productivity in two temperate forests in Northeast China

Forests are rich in biodiversity and high in productivity, and understanding the relationship between biodiversity and productivity is critical to the sustainable management of forest ecosystems. Although biodiversity and other factors contribute to forest productivity to varying degrees, it is unclear whether spatial scale (or plot size) influences this relationship. In this study, we analyzed the impacts of biodiversity, trait composition, structural attributes, and soil fertility on forest productivity at three scales in two temperate old-growth forests. We found that structural attributes, including basal area and stand density, were positively correlated with productivity and were consistently the strongest drivers of productivity changes in both forest types. Trait composition had a weak direct positive correlation with productivity. Soil nitrogen had positive effects on productivity, and soil moisture content had negative effects, both of which increased with increasing plot size. Different results for the effect of biodiversity on productivity were found between the two forests. In the mixed broadleaved-Korean pine forest, diversity correlated positively with productivity, and the strength of the relationship increased with increasing plot size. In contrast, in the spruce-fir valley forest, diversity had a direct positive correlation with productivity at 10 m × 10 m, no significant effect at 20 m × 20 m, and a negative correlation at 30 m × 30 m. Our results suggest that the contribution of vegetation attributes and soil fertility to forest productivity varies with scale. Despite the fact that both the niche complementarity hypothesis and the mass ratio hypothesis act simultaneously in forests, they have limited effects on productivity. Stand structural attributes play a key role in elucidating the biodiversity-productivity relationships, and they may serve as a more significant regulator of forest productivity than diversity. At the same time, the role of soil fertility in regulating productivity cannot be ignored.

Differences and similarities in radial growth of Betula species to climate change

Betula platyphylla and Betula costata are important species in mixed broadleaved-Korean pine (Pinus koraiensis) forests. However, the specific ways in which their growth is affected by warm temperatures and drought remain unclear. To address this issue, 60 and 62 tree-ring cores of B. platyphylla and B. costata were collected in Yichun, China. Using dendrochronological methods, the response and adaptation of these species to climate change were examined. A “hysteresis effect” was found in the rings of both species, linked to May–September moisture conditions of the previous year. Radial growth of B. costata was positively correlated with the standardized precipitation-evapotranspiration index (SPEI), the precipitation from September to October of the previous year, and the relative humidity in October of the previous year. Growth of B. costata is primarily restricted by moisture conditions from September to October. In contrast, B. platyphylla growth is mainly limited by minimum temperatures in May–June of both the previous and current years. After droughts, B. platyphylla had a faster recovery rate compared to B. costata. In the context of rising temperatures since 1980, the correlation between B. platyphylla growth and monthly SPEI became positive and strengthened over time, while the growth of B. costata showed no conspicuous change. Our findings suggest that the growth of B. platyphylla is already affected by warming temperatures, whereas B. costata may become limited if warming continues or intensifies. Climate change could disrupt the succession of these species, possibly accelerating the succession of pioneer species. The results of this research are of great significance for understanding how the growth changes of birch species under warming and drying conditions, and contribute to understanding the structural adaptation of mixed broadleaved-Korean pine (Pinus koraiensis) forests under climate change.

Microbial community and enzyme activity respond differently to seasonal and edaphic factors in forest and grassland ecosystems

Although microbial community and function patterns have been extensively studied, little is known about whether the patterns are consistent in different ecosystems and how they are influenced by seasonality or other environmental factors. To test the driving factors of microbial communities and potential functions, we collected soil samples from five forests (mixed broadleaved-Korean pine forest, mixed pine and oak forest, deciduous broadleaved mixed forest, subtropical evergreen broad-leaved forest and tropical rainforest) and three grassland ecosystems (meadow steppe, semi-arid grassland and arid grassland) across China in three seasons (spring, summer and autumn). Microbial diversity based on the sequencing of 16S rRNA gene for bacteria and internal transcribed spacer (ITS) genes for fungi were measured, and potential functions represented by soil extracellular enzyme activities (EEAs) were analyzed. The results found that soil EEAs were significantly higher in summer than in spring and autumn, and both bacterial and fungal richness indices showed greater seasonal fluctuations than the diversity. Fungal richness indices were highest in summer in both forest and grassland ecosystems, while the lowest were observed in spring for forest and in autumn for grassland, respectively. In addition, fungal communities were closely related to ecosystem types, while bacterial communities were not significantly different across ecosystems and exhibited a broader habitat niche breadth, but the relative abundance of dominant bacterial phyla showed stronger correlations with environmental variables (including climate, soil properties and nutrients) in grassland than in forest ecosystems. The decoupling of microbial community and EEAs was observed in both forest and grassland ecosystems, indicating the function redundancy of soil microorganisms. The present study provided crucial information about the effects of ecosystem types, seasonality and edaphic factors on soil microbial communities and EEAs, and could advance the understanding of soil potential function responses to environmental changes.

Dynamics of glomalin-related soil protein and soil aggregates during secondary succession in the temperate forest

Despite the key role of glomalin-related soil protein (GRSP) in soil organic C (SOC) and soil aggregate stability, the influence of secondary successional processes on GRSP and the interrelationship of GRSP on SOC and its soil aggregate stability is unclear. Based on this, four stages of the secondary succession (including 20-, 32–, 47-, and 61-year-old stands) and the primary broad-leaved Korean pine (Pinus koraiensis) mixed forest were selected. The results showed that total GRSP (T-GRSP), easily extractable GRSP (EE-GRSP), SOC, mean weight diameter (MWD), and geometric mean diameter (GMD) all tended to increase with the secondary succession at 0–30 cm soil layer. The secondary succession contributed to the accumulation of GRSP content, so much so that after 61 years, both EE-GRSP and T-GRSP reached the level of the primary forest. EE-GRSP, T-GRSP, SOC, MWD, GMD, and GRSP/SOC significantly decreased with the deepening of soil depth in all successional stages. In addition, during the 20- and 32 year-old stands of secondary succession, the proportion of GRSP in the SOC was relatively high. With the progress of secondary succession, the content of macroaggregates (>0.25 mm) in the soil increased significantly and was not significantly different from the primary forest. The correlation analysis showed that T-GRSP was more correlated with SOC than EE-GRSP, while EE-GRSP was more correlated with MWD than T-GRSP. Additionally, there was also a significant positive correlation between MWD and SOC at 0–20 cm soil layer. Our results elucidate that GRSP may stabilize SOC pools by direct contribution to SOC in the early secondary succession, and the stabilizing effect on SOC is more pronounced in the later stages by forming macroaggregates. This enables us to understand the ecological functions played by GRSP in soil C sequestration and the enhancement of soil stability during the secondary succession.

Driving mechanisms of productivity stability vary with selective harvesting intensities in a mixed broad-leaved Korean pine forest

Key messageWe found that the stabilizing mechanisms for forest productivity varied across harvesting intensities in a mixed broad-leaved Korean pine forest. Effects of overyielding at high species richness and species asynchrony occurred only in unharvested and lightly harvested plots, whereas asymmetries between individuals of different size contributed significantly to stabilizing productivity when harvestings became intensive.ContextUnderstanding the driving factors of forest ecosystem stability has become increasingly crucial in forest management. However, it remains unclear whether and how the stabilizing mechanisms of forest productivity might be influenced by management practices.AimsWe related the temporal stability of aboveground biomass productivity to harvesting history. We further tested how three key driving mechanisms of stability might be modulated by selective harvesting intensities.MethodsBased on a 10-year monitoring (five repeated tree inventories) of a mixed broad-leaved Korean pine forest in Northeastern China recovering from selective harvesting, we examined the relative importance of two diversity-dependent mechanisms (overyielding and species asynchrony) and one size-dependent mechanism (asymmetric growth) for productivity stability across a wide range of intensities (0–73.4% basal area removed).ResultsWe found that selective harvesting significantly lowered the productivity stability, species asynchrony, and growth dominance coefficient. Growth dominance coefficient had an overall stronger effect on stability than species richness and asynchrony. Moreover, the strengths of stabilizing mechanisms varied across harvesting intensities: effects of overyielding at high species richness and species asynchrony were detected only in unharvested and lightly harvested plots, whereas the explanatory power of growth dominance coefficient outweighed the diversity-related variables when harvesting became intensive.ConclusionsWe emphasized the importance to consider both diversity- and size-related explanatory variables as potential mechanisms for the temporal stability of forest productivity. In fact, how growth is partitioned among trees of different species as well as sizes may co-determine the response of forest stability to disturbances.

Responses of economic and anatomical leaf traits to soil fertility factors in eight coexisting broadleaf species in temperate forests

The multidimensionality of leaf traits allows plants to have diverse survival strategies to adapt to complex living environments. Whether the anatomical traits of leaves are associated with leaf economic traits and which group of traits are more strongly correlated with soil fertility factors remains unclear. We measured four leaf economic traits, four anatomical traits, and five soil fertility factors of eight coexisting broadleaf species distributed in mixed broadleaved-Korean pine (Pinus koraiensis) forests located in Northeast China. Results show a strong interdependence between economic and anatomical traits (p < 0.05). The range of variation between economic and anatomical traits were almost equal, but the causes of variation were different. Specific leaf area was positively correlated with the abaxial epidermis, negatively correlated with the ratio of spongy tissue to leaf thickness (ST/LT), and not correlated with adaxial epidermis. Leaf dry matter content was negatively correlated with the abaxial epidermis and adaxial epidermis, positively correlated with ST/LT. Specific leaf area, palisade tissue, and ST/LT showed stronger correlation with soil fertility factors than other traits. Soil fertility factors dominating trait variation were dependent upon the trait. Our results suggest anatomical traits can be considered in economic trait dimension. The coupled relationship between anatomical and economic traits is potentially a cost-effective adaptation strategy for species to improve efficiency in resource utilization. Our results provide evidence for the complex soil-trait relationship and suggest that future studies should emphasize the role of anatomic traits in predicting soil fertility changes.

Forest Conversion Changes Soil Particulate Organic Carbon and Mineral-Associated Organic Carbon via Plant Inputs and Microbial Processes

Primary forest conversion greatly influences soil organic carbon (SOC) sequestration. However, our understanding of how primary forest conversion affects SOC fractions and chemical component evenness remains limited. We examined how primary forest conversion (from primary mixed broadleaved Korean pine forest to secondary broadleaved forest and coniferous plantation) affects free particulate OC (POC), aggregate-occluded POC, mineral-associated OC (MAOC), and their chemical component evenness via plant inputs (e.g., litter and fine roots) and microbial properties (e.g., microbial biomass and residue C) in Northeast China. Primary forest conversion led to a large increase in litter and fine root quality (lower C/N ratio), SOC, and MBC of secondary forests and a reduction in litter and fine root quantity and quality, SOC, MBC, and microbial residue C of plantations, which drove changes in POC and MAOC. As a result, after conversion to secondary forests, free POC decreased by 20.3% and aggregate-occluded POC increased by 57.2%. After conversion to plantations, free POC increased by 49.1%, while aggregate-occluded POC and MAOC decreased by 42.4% and 9.0%, respectively. Free POC was negatively correlated with fine root biomass. Aggregate-occluded POC and MAOC were positively correlated with litter and fine root quality, MBC, and microbial residue C. Meanwhile, forest conversion decreased the evenness of free and aggregate-occluded POC chemical components in secondary forests, with O-alky C being higher and aromatic C being lower, while MAOC was not affected by forest conversion. The evenness of free and aggregate-occluded POC chemical components was associated with litter and fine root quality, and that of MAOC was associated with MBC and microbial residue C. High-quality plant inputs benefit OC sequestration in soil aggregates and MAOM through microbial assimilation and residue accumulation after primary forest conversion. Future forest management should consider tree species with high-quality input as a possible compensation for climate change by sequestering more OC in soil aggregates.

Sensitivity of forest composition and productivity to climate change in mixed broadleaved-Korean pine forest of Northeastern China

Temperate forest is one of the largest forest biomes and is undergoing remarkable shifts in forest composition and ecosystem productivity under warming climates. However, there are considerable uncertainties when predicting future dynamics of temperate forest ecosystems partly because of the uncertainties in future climate predictions. Sensitivity analysis provides an effective mean to evaluate the uncertainties in the predicted forest responses to climate change. Here we evaluated the sensitivity of forest composition and productivity to climate change in the mixed broadleaved-Korean pine forest, a keystone temperate forest type in northeast China. In this study, we used a process-based forest dynamic model, FORMIND, to simulate and predict the response of the mixed broadleaved-Korean pine forest under climate change based on plant functional types (PFTs), and we performed model calibration using forest investigation. We then designed a factorial experiment to quantify the sensitivity to temperature and precipitation of forest composition and ecosystem productivity. Results showed that the uncertainty in future climate predictions could result in divergent responses of forest composition and ecosystem productivity to climate change over the 21st century. The response of PFTs to climate (temperature and precipitation) varied in terms of aboveground biomass. Both shade-tolerant and shade-intolerant PFTs exhibited higher sensitivity (>80% for most of the PFTs) to temperature than precipitation, yet they responded oppositely to climate warming with shade-tolerant PFTs generally increasing but shade-tolerant PFTs decreasing. Moderate shade-tolerant PFTs showed higher precipitation sensitiveness (>50%). Such differences in response and sensitivity of PFTs to climate change are related to PFTs’ competitiveness. Ecosystem productivity exhibited a higher sensitivity (≥50%) to temperature than to precipitation. There was more increase in ecosystem respiration than gross primary productivity (GPP) under warming climate, leading to a decrease in carbon sequestration and net ecosystem exchange (NEE). Our study addresses the importance of evaluating the sensitivity of a forest ecosystem model to climate change, which is relatively less studied. The insight from the study may help design effective forest management strategies to cope with future climate change.

Soil water content and nitrogen differentially correlate with multidimensional leaf traits of two temperate broadleaf species

The variation and correlation of leaf economics and vein traits are crucial for predicting plant ecological strategies under different environmental changes. However, correlations between these two suites of traits and abiotic factors such as soil water and nitrogen content remain ambiguous. We measured leaf economics and vein traits as well as soil water and nitrogen content for two different shade-tolerant species (Betula platyphylla and Acer mono) in four mixed broadleaved-Korean pine (Pinus koraiensis) forests along a latitudinal gradient in Northeast China. We found that leaf economics traits and vein traits were decoupled in shade-intolerant species, Betula platphylla, but significantly coupled in a shade-tolerant species, A. mono. We found stronger correlations among leaf traits in the shade tolerant species than in the shade intolerant species. Furthermore, leaf economic traits were positively correlated with the soil water gradient for both species, whereas vein traits were positively correlated with soil water gradient for the shade intolerant species but negatively correlated in the shade tolerant species. Although economic traits were positively correlated with soil nitrogen gradient in shade intolerant species but not correlated in shade tolerant species, vein traits were negatively correlated with soil nitrogen gradient in shade tolerant species but not correlated in shade intolerant species. Our study provides evidence for distinct correlations between leaf economics and vein traits and local abiotic factors of species differing in light demands. We recommend that the ecological significance of shade tolerance be considered for species when evaluating ecosystem functions and predicting plant responses to environmental changes.

中国温带典型森林植物比叶面积的空间格局及其影响因素

比叶面积（SLA）能够反映植物自身生长对策、对光能的捕获能力、对外界环境变化的适应和对可利用资源的分配策略，对植物的生境适应状况和群落的自然演替程度也起到重要的指示作用。为了深入了解温带森林植物SLA随空间变化的变异特征及其影响因素，跨越1200 km选取中国东北部12个典型温带森林（寒温带兴安落叶松林、温带红松针阔混交林和暖温带落叶阔叶栎林），通过对样地内物种进行系统性的调查，分析了植物SLA在空间上的变化规律及环境因素的影响效应。结果显示：中国温带森林植物SLA范围为2.02-99.65 m²/kg（均值为34.18 m²/kg），其中乔木SLA范围为2.02-58.74 m²/kg（均值为21.32 m²/kg），灌木SLA范围为2.88-99.65 m²/kg（均值为31.60 m²/kg），草本SLA范围为4.66-98.53 m²/kg（均值为38.75 m²/kg）。SLA在不同森林类型之间差异显著，具体表现为：温带红松针阔混交林 > 暖温带落叶阔叶栎林 > 寒温带兴安落叶松林。SLA受到气候因素和土壤因素的影响，其中随着年均降水、土壤碳氮含量的增加显著增加；随着年均温度、紫外辐射、光合有效辐射，呈先增加后降低的趋势；随着土壤碳氮比的增加显著降低。以上结果揭示了温带森林SLA的空间变异规律，可以为将来区域乃至全球尺度下植物功能性状研究提供理论支撑。;Specific leaf area (SLA) can reflect plant growth strategies, the ability to capture light energy, adaptation to changing environments, and allocation strategies of available resources. SLA critically plays an important role in indicating plant adaptation to their habitat and the degree of community succession as well. SLA is a complex of plant leaf area and weight, and is defined as the ratio of single leaf area to its dry weight. The current research on SLA in temperate forests mostly focused on the spatial variation of dominant species or just a certain tree, and the vertical variation among forests. However, the systematic investigation of the entire community was rarely carried out. This research was conducted in the northeast of China in which covered three forest types. These types were respectively cold-temperate Larix gmelinii forests, temperate broad-leaved Korean pine mixed forests and warm-temperate deciduous broad-leaved Oak forests. This study selected 12 typical temperate forests spanning 1200 km, and performed a systematic survey to explore the spatial patterns and influencing factors of plant SLA. The results showed that the SLA of China's temperate forest plants ranged from 2.02 to 99.65 m²/kg (mean, 34.18 m²/kg). Specifically, the SLA range was 2.02-58.74 m²/kg for trees (mean, 21.32 m²/kg), 2.88-99.65 m²/kg for shrubs (mean, 31.60 m²/kg), and 4.66-98.53 m²/kg for herbs (mean, 38.75 m²/kg). Plant SLA significantly differed among different forest types, with the greatest SLA in temperate broad-leaved Korean pine mixed forest, followed by warm-temperate deciduous broad-leaved Oak forest and cold-temperate Larix gmelinii forest. Significant latitudinal pattern of plant SLA was observed. As latitude increased, SLA initially increased and then decreased. SLA was found to be affected by both climatic and soil factors. SLA increased significantly with the increasing mean annual precipitation, soil carbon content, and soil nitrogen content. However, with the increase of mean annual temperature, ultraviolet radiation, and photosynthetically active radiation, SLA first increased, followed by a decline. Moreover, it decreased significantly as the soil carbon to nitrogen ratio increased. In summary, this study reveals the spatial variation of SLA in temperate forests, and it can not only provide a new perspective for the study on the response of different forest ecosystems to global change, but also provide an important theoretical basis for the development of the adaptive management of natural forests in China. Moreover, it also provides a theoretical support for future studies on plant functional traits at the regional and global scales.

长白山阔叶红松林紫椴种群结构与动态特征

PDF HTML阅读 XML下载 导出引用 引用提醒 长白山阔叶红松林紫椴种群结构与动态特征 DOI: 10.5846/stxb202106191629 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家科技基础资源调查项目(2019FY101602) Population structure and dynamic characteristics of Tilia amurensis in broad-leaved Korean pine mixed forest in Changbai Mountain 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:紫椴(Tilia amurensis)为国家二级重点保护野生植物。以长白山北坡阔叶红松林内的紫椴种群为研究对象,通过建立种群静态生命表、绘制存活曲线、计算数量动态指数并引入生存函数和时间序列预测模型定量描绘其结构与动态特征。结果表明:1)种群年龄结构呈不规则金字塔形,幼龄阶段(Ⅰ-Ⅳ龄级)个体数之和占个体总数的67.26%。2)种群存活曲线接近Deevey-Ⅲ型,表明植株在幼龄阶段死亡率高。3)总体数量动态变化指数Vpi>V'pi>0,表明紫椴种群为增长型,但V'pi趋近于0,结合死亡率(qx)和消失率(Kx)曲线呈现出连续性先增后降的复杂动态变化趋势,可知该种群不稳定且在干扰情况下增长趋势不明显。4)生存函数分析显示,种群在Ⅲ-Ⅳ龄级间达到平衡状态,尔后进入衰退期且从第Ⅷ龄级开始进入生理衰退。5)时间序列预测分析表明,在未来2、3、4、5、6、7、8、9、10龄级时间后,紫椴幼龄个体数逐渐减小,而中、成和老龄个体数量将逐渐增加,说明未来紫椴种群的增长主要依靠后者。生物学特性和生境是限制紫椴种群增长的主要原因。建议加强幼苗抚育工作,提高幼苗和小树的存活率,保护和改善生存环境,从而促进紫椴种群的自然更新和恢复。 Abstract:Tilia amurensis is the second-class national protection species. In this study, the population structure and dynamic characteristics of T. amurensis distributed in Changbai Mountain were analyzed by population statistics, including static life table, survival curve, the quantity dynamic index, survival function, and time series prediction model. The results showed that:1) the age-class structure of T. amurensis population was irregular pyramid type, and the sum of number of young individuals (I-IV age class) accounted for 67.26% of the total individuals. 2) The survival cure was close to Deevey-Ⅲ type, which showed that the number of young individuals was abound while their survival rate was low. 3) The population dynamics index was Vpi>V'pi>0, indicating that T. amurensis population belonged to the increasing type. However, the index V'pi closed to 0, and the curve of mortality rate (qx) and vanish rate (Kx) showed a complex dynamic trend of continuous increase first and then decrease, which indicated that the population stability was poor and the growth trend was not obvious in the case of disturbance. 4) The analysis of survival function showed that the population reached a balance between the age classes of Ⅲ-Ⅳ, and then entered the decline period. From the age class of Ⅷ, the population entered a physiological decline phase. 5) Time series prediction analysis showed that in the next 2, 3, 4, 5, 6, 7, 8, 9, 10 age classes, the number of young individuals would gradually decrease, while the number of middle-aged, adult and old individuals would gradually increase, indicating that the maintenance of T. amurensis population mainly depends on the latter in the future. The biological characteristics and habitat are the main factors limiting the population growth of T. amurensis. We suggest that the seedling raising should be strengthened to improve the survival rate of the seedlings and small trees, and the habitat should also be protected to enhance natural regeneration and restoration of the T. amurensis population. 参考文献 相似文献 引证文献

Use of direct seeding and seedling planting to restore Korean pine (Pinus koraiensis Sieb. Et Zucc.) in secondary forests of Northeast China

The poor natural regeneration of Korean pine represents a substantial hurdle limiting the restoration of secondary forests to mixed broad-leaved Korean pine forests (MBKPFs). Active restoration based on direct seeding or planting seedlings is accordingly considered to be a prerequisite for promoting Korean pine recruitment in secondary forests. To evaluate the most effective practices for restoring Korean pine in secondary forests, we studied the effects of microsites associated with gaps of different sizes and within-gap locations on direct seeding (rodent access/exclusion and soil/litter cover) and seedling planting (1-, 2-, and 3-year-old seedlings). We found that an average of 82.4% of sown seeds were eaten by rodents, with only 9.9% germinating and surviving after two growing seasons. Among the germinated seedlings, 37.6% were subsequently excised by rodents, whereas 6% died due to other natural causes. Furthermore, compared with the control sites (forest understorey), we detected no significant differences among the different microsites with respect to an effective reduction in rodent damage or promotion of seed germination, whereas rodent exclusion was more effective in protecting seeds from predation than the effect of microsite. With regards to planted seedlings, we found that the proportion of survival and relative root collar diameter growth were highest in the center (64.1%) and edge (60.0%) sites of large gaps, and that the survival of planted seedlings (43.7%) was considerably higher than that of seedlings derived from directly sown seeds (9.9%). Collectively, our findings indicate that, owing to seed predation and seedling excision by rodents, direct seeding with either mesh or soil cover would not represent an effective strategy for promoting Korean pine recruitment in secondary forests. Accordingly, for the purposes of restoring secondary forests to MBKPFs, we recommend planting 3-year-old Korean pine seedlings in large gaps within secondary forests.

Long-term (42 years) effect of thinning on soil CO2 emission in a mixed broadleaved-Korean pine (Pinus koraiensis) forest in Northeast China

Thinning is an important forest management practice that has great potential to influence regional soil carbon storage and dynamics. The present study measured soil respiration (RS, the efflux of CO2 emitted) and its two components (heterotrophic (RH) and autotrophic (RA) respiration) from soil 42 years after thinning in comparison to un-thinning (control). Autotrophic respiration was significantly greater in the thinning plot, approximately 44% higher compared to the control, while both Rs and RH were slightly, but not significantly, higher in the thinning plot. Higher fine root biomass might have contributed to the higher Ra in the thinning plot. Both Rs and RH showed clear soil temperature-dependent seasonal patterns, whereas Ra was less responsive to changes in temperature, especially within one specific season. The annual and season-specific temperature sensitivities of RS and RH were lower in the thinning plot, specifically during the mid-growing season. Furthermore, variations in the season-specific temperature sensitivity of Rs and RH were less intense in the thinning plot. We conclude that forest thinning can reduce the temperature sensitivity of RS and RH during the mid-growing season and increase soil CO2 emission in the long term.

阔叶红松林不同演替阶段灌木器官的N、P分配特征

氮（N）、磷（P）是植物生长发育重要的限制元素，N、P以及N、P间的关系是化学计量学研究的重要内容。植物不同器官对N、P的需求存在差异，因此N、P的分配与权衡对植物的生长发育起到重要的调节作用。为了探究阔叶红松（Pinus koraiensis）林不同演替阶段主要灌木器官的N、P化学计量特征及其分配格局，了解灌木的养分限制因子及其分配策略，在黑龙江凉水国家级自然保护区的阔叶红松林四个演替阶段——白桦（Betula platyphylla）次生林、阔叶混交林、针阔混交林和阔叶红松林内，选取主要灌木种，分析了叶片、枝条、茎干和根的N、P化学计量特征以及异速生长关系。结果发现：灌木不同器官之间的N、P含量差异显著，其中叶的N、P含量均为最高，茎干的N、P含量均为最低。所有器官中，叶的N ： P最高，为7.59；根的N ： P最低，为5.47。灌木叶、茎干、根之间的N ： P存在显著差异，而茎干、根与枝条之间的N ： P没有显著差异。阔叶红松林不同演替阶段对灌木同一器官N、P化学计量的影响不同，灌木叶片的N含量在不同演替中具有显著差异，其他器官的差异不显著；不同演替阶段灌木器官的P含量均无显著差异。在不同演替阶段中各器官的N ： P均小于14，说明N元素是阔叶红松林各演替阶段灌木生长的限制因子，而P对灌木的生长没有起到限制作用。研究表明在不同演替阶段中，N、P的异速生长关系普遍存在于灌木器官中，呈现显著的正相关关系；整体上各器官之间的斜率没有显著差异，说明灌木采取保守分配策略，以此来适应环境和满足自身生长发育的需要。;Nitrogen (N) and phosphorus (P) were important limiting elements for plant growth and development in the nature. N, P and their relationship were essential contents in stoichiometry. Different plant organs had different demands for N and P, therefore the allocation and trade-off of N and P played an important role in the growth and development of plants. In order to explore the N and P stoichiometric characteristics and allocation patterns of shrub organs in different successional stages of the mixed broadleaved-Korean pine (Pinus koraiensis) forest, and to understand the nutrient limiting factors and allocation strategies, the dominant shrub species in four successional stages (secondary birch forest, mixed broad-leaved forest, mixed broadleaved-conifer forest and the mixed broadleaved-Korean pine forest) were selected in Liangshui National Nature Reserve, Heilongjiang. In this study, to research the N and P stoichiometric characteristics and allometric relationship, leaves, twigs, stems and roots of shrubs were collected to analyzed. The results showed that the contents of N and P in different organs were significantly different. In addition, the contents of N and P in leaves were the highest, while those in stems were the lowest among all shrub organs. The N:P ratio of leaves was the highest (7.59), and that of roots was the lowest (5.47). N:P ratio in leaves, stems and roots were significantly different, but N:P ratios in stems, roots and twigs were not significantly different. The effects on N and P stoichiometry of the same organ in different successional stages of the mixed broadleaved-Korean pine forest were different. Specifically, the N content in leaves had a significant difference, though the difference in other organs was not significant. There was no significant difference in P content of shrub organs among the four successional stages. In fact, all of N:P ratios were less than 14, which showed that N was always a limiting factor for shrub growth in different successional stages of the mixed broadleaved-Korean pine forest. However, P had no limiting effect on the growth of shrubs. Our research revealed that the allometric relationship of N and P generally existed in shrub organs in different successional stages, presenting a significantly positive correlation. In general, there was no significant difference among the allometric slopes of shrub organs in the mixed broadleaved-Korean pine forest, indicating that the shrub adopted a conservative allocation strategy to adapt to the environment change and satisfy the needs of its own growth and development.

Characteristics of shrub leaf carbon, nitrogen and phosphorus stoichiometry and influencing factors in mixed broadleaved-Korean pine forests at different successional stages

Characteristics of shrub leaf carbon, nitrogen and phosphorus stoichiometry and influencing factors in mixed broadleaved-Korean pine forests at different successional stages

Effects of canopy structure on productivity in a typical mixed broadleaved-Korean pine forest

Effects of canopy structure on productivity in a typical mixed broadleaved-Korean pine forest

Effects of Korean Pine Basal Area in Mixed Broadleaved–Korean Pine Forest Stands on Its Natural Regeneration in Northeast China

Abstract Understanding the natural regeneration of Korean pine (Pinus koraiensis Sieb. et Zucc.) in mixed broadleaved–Korean pine (MBK) forests is crucial for MBK forest conservation and secondary deciduous broadleaved forest restoration. We hypothesized the ratio of Korean pine basal area (RKp) in MBK stands affected its natural regeneration. Regeneration censuses, including the height, root collar diameter, age, and growth stages (younger seedling, older seedling, smaller sapling, and taller sapling) of Korean pine, were conducted in northeast China. Results indicated the stem density and age composition of younger seedlings were positively correlated with RKp, whereas those of the saplings were negatively correlated with RKp. In the stands with lower RKp (<80% in Lesser Khingan Mountains [LKM]; <40% in Lushuihe Forestry Bureau [LFB]), individuals in all growth stages regenerated well with an age span of 65 yr. However, the regeneration of taller saplings was severely inhibited with increasing RKp (LKM: RKp ≥ 80%; LFB: RKp ≥ 40%). In summary, RKp significantly affected the natural regeneration of Korean pine in MBK forests. The basal-area thresholds limiting regeneration were found to be 80% in LKM stands and 40% in LFB stands. These basal-area thresholds provided evidence of why the zonal climax was MBK forests rather than pure Korean pine forests.

Importance of organ age in driving intraspecific trait variation and coordination for three evergreen coniferous species

Plant functional traits play an important role in plant growth and community composition in forest ecosystem. However, how the intraspecific trait variations for both leaf and branch were driven by organ age is less clear. We chose three evergreen coniferous species in the mixed broadleaved-Korean pine (Pinus koraiensis) forest in Northeast China and measured the functional traits for leaf and branch across organ ages. We mainly evaluated the influences of needle or branch age on the intraspecific trait (both leaf and branch) variations and bivariate correlation of traits for three species. We found that organ age had the largest contributions to the intraspecific variations in most traits for the three species. Current organ had high specific leaf area, high leaf nitrogen content, high specific branch length and low leaf and branch dry matter content, while perennial organ showed the opposite trend, indicating the differentiation of ecological strategies at different organ ages. The organ age significantly modified most of the trait-trait relationships, indicating that the transformation of the plant ecological strategy was driven by organ age. Unexpectedly, the variation in plant hydraulic traits was not affected by branch age and decoupled with most other traits for the three species. Our results suggest that the organ age effect should be incorporated into future studies of trait-based ecology for evergreen coniferous species.

Comparison of Soil Greenhouse Gas Fluxes during the Spring Freeze–Thaw Period and the Growing Season in a Temperate Broadleaved Korean Pine Forest, Changbai Mountains, China

Soils in mid-high latitudes are under the great impact of freeze–thaw cycling. However, insufficient research on soil CO2, CH4, and N2O fluxes during the spring freeze–thaw (SFT) period has led to great uncertainties in estimating soil greenhouse gas (GHG) fluxes. The present study was conducted in a temperate broad-leaved Korean pine mixed forest in Northeastern China, where soils experience an apparent freeze–thaw effect in spring. The temporal variations and impact factors of soil GHG fluxes were measured during the SFT period and growing season (GS) using the static-chamber method. The results show that the soil acted as a source of atmospheric CO2 and N2O and a sink of atmospheric CH4 during the whole observation period. Soil CO2 emission and CH4 uptake were lower during the SFT period than those during the GS, whereas N2O emissions were more than six times higher during the SFT period than that during the GS. The responses of soil GHG fluxes to soil temperature (Ts) and soil moisture during the SFT and GS periods differed. During the SFT period, soil CO2 and CH4 fluxes were mainly affected by the volumetric water content (VWC) and Ts, respectively, whereas soil N2O flux was influenced jointly by Ts and VWC. The dominant controlling factor for CO2 was Ts during the GS, whereas CH4 and N2O were mainly regulated by VWC. Soil CO2 and N2O fluxes accounted for 97.3% and 3.1% of the total 100-year global warming potential (GWP100) respectively, with CH4 flux offsetting 0.4% of the total GWP100. The results highlight the importance of environmental variations to soil N2O pulse during the SFT period and the difference of soil GHG fluxes between the SFT and GS periods, which contribute to predicting the forest soil GHG fluxes and their global warming potential under global climate change.

Effect of canopy gap size on soil respiration in a mixed broadleaved-Korean pine forest: Evidence from biotic and abiotic factors

Understanding the effects of forest structure, the frequency and size of canopy gaps is pivotal for precisely modelling forest soil carbon budgets. We aimed to determine the differences in soil respiration between closed canopy areas and canopy gaps with various sizes and how soil respiration is affected by biotic and abiotic factors, e.g., soil nutrients, soil microbial biomass and community composition, enzyme activities and fine root biomass. Soil respiration and these environmental factors were measured in eleven tree fall gaps (separated into small, medium and large with sizes ranging from 20 m2 to 450 m2) and three control plots in a mixed broadleaved-Korean pine forest during the growing season. Our results showed that soil respiration was similar between the control and small canopy gaps, while it was 17–49% lower in the medium and large canopy gaps compared to that of the control. There was a significant parabolic relationship between soil respiration and soil moisture, and the optimum moisture was approximately 40%. Fine root biomass and soil enzyme activities showed positive effects on soil respiration across different levels of canopy gaps. Furthermore, soil respiration was significantly declined with increasing soil microbial diversity (OTUs of bacteria). Our findings demonstrate that canopy gap has significant impact on soil CO2 emission in a temperate mixed forest, however, further studies concerning other forest ecosystem types and larger scale are warranted.