Mixed Pine Forest Research Articles

Mixed Pine Forests in a Hotter and Drier World: The Great Resilience to Drought of Aleppo Pine Benefits It Over Other Coexisting Pine Species

Drought is an important driver of forest dynamics in the Mediterranean region. The forecasted increase in drought frequency and severity can notably influence tree growth, forest structure, composition and productivity. Understanding how coexisting tree species respond to drought is thus crucial to understand which are less vulnerable and will perform better in a warmer and drier world. To assess drought vulnerability, we used dendrochronology to study the radial growth trends and responses to a drought index of four pine species (Pinus halepensis, Pinus pinea, Pinus nigra, and Pinus sylvestris) coexisting in North-eastern Spain. We reconstructed the growth of each species and evaluated their short- and long-term growth response to drought for the common period 1980–2017. The growth of the four pine species depended on water availability and high early spring temperatures impacted the growth of P. nigra and P. sylvestris negatively. The occurrence of a severe drought between 2005 and 2007 lead to marked growth reductions in the four species, but it was greater in magnitude in P. pinea and P. halepensis in 2005, and in P. nigra in 2007. The results of basal area increment models at the individual tree level suggested that P. halepensis trees grow more than the rest of species. After accounting for age and drought effects, P. nigra and P. sylvestris displayed negative growth trends in the 2008–2017 period while P. pinea and P. halepensis displayed positive growth trends. P. sylvestris was the most resistant species and P. pinea the less resistant. Conversely, P. halepensis and P. pinea were slightly more resilient than P. sylvestris. Moreover, P. sylvestris was the species displaying the highest autocorrelation and the lowest coefficient of variation in ring-width indices. A marked drop in the autocorrelation of P. pinea ring-width index was observed in response to the 2005 drought. These results indicate that all study species are vulnerable to drought but in different degrees. The strong resilience capacity of P. halepensis suggests that it will better thrive in a drier future, but mixed pine forests, such as the one here studied, may contract or become rare due to the strong sensitivity of P. pinea to drought and the lower post-drought performance of P. nigra and P. sylvestris.

Variations in Litterfall Dynamics, C:N:P Stoichiometry and Associated Nutrient Return in Pure and Mixed Stands of Camphor Tree and Masson Pine Forests

Litterfall, directly and indirectly, affects the soil physicochemical properties, microbial activity, and diversity of soil fauna and flora by adding organic matter and nutrients to the soil. This study explores litterfall dynamics such as litterfall production, litter decomposition rate, and associated nutrient return in three forest types, that is, camphor tree forest (CTF), Masson pine forest (MPF), and camphor tree and Masson pine mixed forest (CMF), in subtropical China. Results showed that CMF had the highest mean annual litterfall production (4.30 ± 0.22 t ha−1), which was significantly higher than that of MPF (3.41 ± 0.25 t ha−1) and CTF (3.26 ± 0.17 t ha−1). Leaf represented the major fraction of litterfall, constituting over 71% of the total litterfall mass in the three forest types. The contribution of branch litter was 16.3, 8.9, and 16.9%, and miscellaneous litter was 12.6, 18.9, and 11.1% in CTF, MPF, and CMF, respectively. The concentration of macronutrients ranked as N > Ca > K > Mg > P in all litter fractions. The total annual macronutrient return to the soil from the litterfall was in order as CTF (74.2 kg ha−1‧yr−1) > CMF (70.7 kg ha−1‧yr−1) > MPF (33.6 kg ha−1‧yr−1). The decomposition rate was higher in leaf litter than in branch litter throughout the three forests. Among the forest types, the leaf and branch decomposition rates were in a pattern: CTF > CMF > MPF. The ratio of C/N in both leaf and branch litters was significantly higher in MPF than in CTF and CMF, while no significant differences in N/P ratio were found in these litters among the three forests. The high N:P ratios in leaf litter (23/30) and the branch (24/32) litter indicated the high N returning and low nutrient returning to the soil. Our results suggested that the broadleaved forests have faster litter decomposition and higher macronutrient returns than conifer forests. Moreover, the litter decomposition rate was mainly associated with litterfall quality and chemical composition. The introduction of broadleaved trees into monoculture coniferous stands could increase litter production nutrients return, and thus, it had advantages in soil nutrients restoration and sustainable forest management.

Changes in Carbon Storage of Masson Pine Forests along a Latitudinal Gradient with Different Stand Structures in Southern China

The spatial patterns of carbon pool in landscape vary greatly with variation of forest structures and climate conditions. In this field study, the carbon storage in overstory, understory, litter layer of plants and soil carbon in forests was investigated in 26-28 year-old Masson pine (Pinus massoniana) pure and mixed forests along a latitudinal gradient (20–30 °N) crossing Hunan and Guangxi provinces of China, during the period of May 2015–August 2017. We found that the total carbon storage in Masson pine forests ranged 88.92–149.41 Mg/ha, of which 54.03% occurred in aboveground compound and 45.97% occurred belowground. The overall total carbon storage distribution was 34.62–68.72 Mg/ha, 3.82–10.19 Mg/ha, 2.37–3.96 Mg/ha, and 6.06–12.08 Mg/ha in stems, branches, leaves, and roots, respectively. The carbon storage in the overstory of forest stands and forest soils significantly decreased with increasing latitude, while the carbon storage in the understory and litter of the forest stands significantly increased as the latitude increased. The overall carbon storage significantly decreases by 8.26 Mg/ha in Masson pine forests as the latitude increased by one degree. The carbon storage increased by 8.43% in Masson pine mixed forests compared to the pure forest stands after the transformation from the pure forest stands into the mixed forest stands ∼ 15 years later. The results of changes in carbon storage in the studied forests with the latitudinal gradient could be attributed to variations in hydrothermal conditions with changing latitudes. The forest structure with different tree species composition was another important factor regulating carbon storage in forest ecosystems at the same latitude. The results provided a scientific basis for better understanding of latitudinal variation and spatial distribution of carbon storage in Masson pine forest stands with optimal forest stand structures in subtropical region of China.

Year-round multi-scale habitat selection by Crested Tit (Lophophanes cristatus) in lowland mixed forests (northern Italy)

Determining how animals respond to resource availability across spatial and temporal extents is crucial to understand ecological processes underpinning habitat selection. Here, we used a multi-scale approach to study the year-round habitat selection of the Crested Tit (Lophophanes cristatus) in a semi-natural lowland woodland of northern Italy, analysing different habitat features at each scale. We performed Crested Tit censuses at three different spatial scales. At the macrohabitat scale, we used geolocalized observations of individuals to compute Manly's habitat selection index, based on a detailed land-use map of the study area. At the microhabitat scale, the trees features were compared between presence and absence locations. At the foraging habitat scale, individual foraging birds and their specific position on trees were recorded using focal animal sampling. Censuses were performed during both the breeding (March to May) and wintering (December to January) seasons. At the macrohabitat scale, the Crested Tits significantly selected pure and mixed pine forests and avoided woods of alien plant species, farmlands and urban areas. At the microhabitat scale, old pine woods with dense cover were selected, with no significant difference in the features of tree selection between the two phenological phases. At the foraging habitat scale, the species was observed spending more time foraging in the canopies than in the understorey, using mostly the portion of Scots Pine (Pinus sylvestris) canopies closer to the trunk in winter, while during the breeding period, the whole canopy was visited. Overall, breeding and wintering habitats largely overlapped in the Crested Tit. Based on our findings, lowland Crested Tits can be well defined as true habitat specialists: they are strictly related to some specific coniferous woodland features. Noteworthily, compared to other tit species, which normally show generalist habits during winter, the Crested Tit behaves as a habitat specialist also out of the breeding season. Our study stressed the importance of considering multi-scale (both spatial and phenological) habitat selection in birds.

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

Diversity and distribution of the large centipedes (Chilopoda: Scolopendromorpha) in the Phia Oac - Phia Den National Park, Vietnam

The scolopendromorph fauna of the Phia Oac - Phia Den National Park, northernmost Vietnam has been studied. As a result, a total of 17 species in eight genera and three families have been recorded in five different types of habitats (wood forest, bamboo forest, wood-bamboo mixed forest, pine forest, and grassland-shrubs) and from three elevation range (<1,000 m, 1,000–1,600 m, and >1,600 m). Scolopendridae is the most diverse family with nine recorded species. Of the five habitats, most species have been found in wood forests and wood-bamboo mixed forests (11 species each habitat), and at the elevation range of 1,000–1,600 m (15 species). The research also recommended that this number does not reflect the true biodiversity of this region; more intensive surveys are needed to have a better understanding of the scolopendromorph diversity in the Phia Oac - Phia Den National Park.

Changes in soil ammonia oxidizers and potential nitrification after clear-cutting of boreal forests in China.

The Korean pine and broad-leaved mixed forests are the most typical and complete ecosystem among the global boreal forests, with extremely important ecological functions. However, few studies on the changes of soil ammonia oxidizers and potential nitrification after clear-cutting of forests are reported. In this study, in contrast to primary Korean pine forests, nitrate (NO3-) was significantly higher in secondary broad-leaved forests, while ammonium (NH4+) was on the contrary. The abundance of ammonia-oxidizing bacteria (AOB) was greatly higher in secondary broad-leaved forests, while levels of ammonia-oxidizing archaea (AOA) were not significantly different between them. The significant differences of community structure of AOA and AOB were observed in different forest types and soil layers. Compared with AOA, community compositions of AOB was more sensitive to forest type. The dominant groups of AOA were Nitrososphaera and Nitrosotalea, and the dominant group of AOB was Nitrosospira, of which Nitrosospira cluster 2 and 4 were functional groups with highly activity. Soil potential nitrification rate (PNR) was higher in secondary broad-leaved forests. Furthermore, PNR and AOB abundance had a significant positive correlation, but no significant correlation with AOA abundance. These results provide insights into the soil nitrogen balance and effects on forest restoration after clear-cutting.

Soil physico-chemical properties have a greater effect on soil fungi than host species in Mediterranean pure and mixed pine forests

Soil fungi are fundamental drivers of forest ecosystem processes. Soil physico-chemical parameters and vegetation features such as host type or stand structure can affect soil fungal communities. However, there is a lack of comprehensive studies describing the relative importance of niche processes (soil physico-chemistry and forest structural drivers) versus neutral processes (geographical distance) driving soil fungal community assemblages, especially in less-studied drought-prone ecosystems such as Mediterranean forests. In this study, we performed Pacific Biosciences sequencing of internal transcribed spacer 2 amplicons to characterize the soil fungal community composition and diversity of 42 forests dominated by either pure Pinus nigra, Pinus halepensis or Pinus sylvestris or a P. nigra–P. halepensis or P. nigra–P. sylvestris mixture. Our specific aims were to identify and disentangle the relative importance of the main soil characteristics and the spatial and forest structural factors that accounted for the greatest proportion of fungal community variation along a regional gradient in the Mediterranean Pre-Pyrenees. Soil parameters accounted for the greatest significant proportion of the total variance in the overall fungal community (25%), in the mycorrhizal (23%) and saprotrophic (22%) communities, while geographical distance accounted for 14% of the variance in the overall fungal community, 7% in the mycorrhizal and 22% in the saprotrophic communities. Conversely, forest structure did not significantly affect the soil fungal community, as fungal composition and diversity did not differ significantly among the pine hosts. Moreover, pH, followed by P and the C:N ratio explained the largest differences in the composition of the overall fungal community and in the mycorrhizal fungal community. By contrast, the largest proportion of differences in saprotrophic composition were explained by geographical distance, closely followed by the C:N ratio and N. Our results show that, in these Mediterranean pine forests, soil parameters are the most important driving forces shaping soil fungal communities at the regional scale given that ectomycorrhizal and saprotrophic fungi were more influenced by soil physico-chemical parameters or geographical distance than by Pinus species or forest structural variables. Finally, P content in soils also emerged as a significant factor driving differences in mycorrhizal communities.

Fine root production and nutrient dynamics in relation to stand characteristics of chir pine mixed banj oak forests in central Himalaya

Stand density and basal area are considered to be an important indicator of aboveground as well as belowground dynamics in forests. To understand the relationship between stand characteristics and fine root dynamics of chir pine (Pinus roxburghii) mixed banj oak (Quercus leucotrichophora) forests in central Himalaya we studied fine root mass, productivity, turnover rate and nutrient dynamics. Four sites were selected on the basis of increasing density and basal area of trees. From each site, ten random fine root samples were collected for one year by sequential coring method, using root corer of 8.0 cm diameter from three depths (0–10, 10–20 and 20–30 cm) on a monthly basis. Total mean fine root mass varied from 2.15 to 3.12 Mg ha−1, with biomass and necromass varying from 1.48 to 1.93 Mg ha−1 and 0.67 to 1.18 Mg ha−1, respectively. In terms of vertical distribution, values of both biomass and necromass decreased with increasing soil depth. Productivity was estimated between 1.24 and 1.51 Mg ha−1 y−1 while turnover rate varied from 0.78 to 0.84 y−1 throughout the sites. Concentration of nitrogen was found higher in live fine roots whereas, phosphorus, potassium and calcium did not show any significant variation between live and dead fine roots. In the present study, higher fine root mass upon increase in density and basal area of trees suggests that stand characteristics positively correlate with fine root mass while nutrient dynamics remain unaffected by stand characteristics as well as seasonal changes.

Overyielding in mixed pine forests with belowground complementarity: impacts on understory

The impact of biodiversity loss on the functioning of forest ecosystems has become a central issue in ecology. Most reports of the positive effects of tree mixture on the biodiversity–productivity relationship focus on mixtures that combine tree species with contrasting traits. Nevertheless, little is known about how coniferous mixtures of the same genus affect forest productivity, what mechanisms are involved, and how the understory is affected. Here, we assessed the effect of mixed versus monospecific stands of Pinus sylvestris L. and P. pinaster Ait. on productivity, its impact on the understory, and its relationship with soil water and fertility, based on research with six triplets (6 triplets × 3 forest stands × 1 plot = 18 plots) in North-Central Spain. Each triplet consisted of two plots dominated either by P. sylvestris or P. pinaster and of one mixed plot that contained both species. Productivity, at the stand and neighborhood levels, and the understory richness, and soil water and fertility at the stand level were analyzed. A positive effect of pine mixture on productivity was observed at the smaller spatial scale, and it had no negative effect on the understory richness. The greater space-use efficiency (higher tree density and basal area) of both Pinus species in the admixtures was related to soil water and fertility niche complementarity. The fundamental role of scale in determining the relationship between species richness and ecosystem functioning in forests is highlighted.

The population status and threats of Taxus cuspidata, a plant species with extremely small populations in China

Taxus cuspidata Siebold et Zuccarini, one of the plant species with extremely small populations in China, is listed as a first-class national key protected wild plant that urgently needs to be rescued. However, there are different viewpoints on the population status of T. cuspidata. To elucidate the current actual population status of T. cuspidata, we conducted a systematic field survey in the distribution area of T. cuspidata in China, and analyzed the size structure, sex ratio, dynamics, and threat factors of T. cuspidata populations. Our results are as follows. (1) T. cuspidata was mainly distributed in Wangqing County, Helong City, Hunchun City of Jilin Province, and Muling City of Heilongjiang Province, while seldom distributed in Liaoning Province. T. cuspidata was distributed in the broad-leaved-conifer-Korean pine mixed forest in Northeast China, mostly as sporadic single individuals or scattered small populations. The highest density of adult individuals of T. cuspidata was 20 individuals/0.1 ha in DHZ, and the highest density of regeneration individuals was 28 individuals/0.1 ha in JGL. There was a significant exponential relationship (p < 0.05) and a serious polarization between the number of adult and regeneration individuals. (2) The T. cuspidata population showed an inverted J-shaped size structure, and its survival curve belonged to the Deevey Ⅲ, in which the number of surviving individuals decreased sharply from the sapling to the seventh size class. The ratio of females to males in the T. cuspidata population was 1:2.30, which was significantly different from 1:1 (p < 0.001). (3) Disturbance intensity was the primary environmental variable affecting the regeneration and adult individuals of T. cuspidata. Interestingly, disturbance factors together with habitat factors explained 41.6% and 59.8% of the variation in the number of regeneration and adult individuals respectively, and habitat factors (29.6%) had a greater independent effect than disturbance factors (17.3%) on regeneration individuals, whereas disturbance factors (16.0%) had a greater independent effect than habitat factors (12.5%) on adult individuals. Taken together, we highlighted that excessive disturbance directly resulted in the sharp decline in the population size and habitat area of T. cuspidata in China. Currently, T. cuspidata is endangered and faced with a high risk of local extinction in China. Therefore, we should continue to pay more attention to this species and we suggest that the International Union for Conservation of Nature (IUCN) could reconsider the threatened category of T. cuspidata.

Eleven New Nearctic Species of Sciophila Meigen Fungus Gnats (Diptera: Mycetophilidae)

Eleven new species of Sciophila Meigen fungus gnats were discovered in mixed pine and hardwood forest in the Lower Peninsula of Michigan. The current effort (and five species in press elsewhere) presents the only Sciophila species known to the author that were described from Michigan. Sciophila ansluta Taber, Sciophila betula Taber, Sciophila enigma Taber, Sciophila impala Taber, Sciophila michigana Taber, Sciophila paludosa Taber, Sciophila platalea Taber, Sciophila rugosa Taber, Sciophila separata Taber, Sciophila sunda Taber, and Sciophila typha Taber are known from adult males. Adult females and immature forms are unknown.

Abiotic and biotic modulators of litterfall production and its temporal stability during the succession of broad-leaf and Korean pine mixed forest

Abiotic and biotic modulators of litterfall production and its temporal stability during the succession of broad-leaf and Korean pine mixed forest

Effects of nitrogen addition on microbial residues and their contribution to soil organic carbon in China's forests from tropical to boreal zone.

Atmospheric nitrogen (N) deposition has a significant influence on soil organic carbon (SOC) accumulation in forest ecosystems. Microbial residues, as by-products of microbial anabolism, account for a significant fraction of soil C pools. However, how N deposition affects the accumulation of soil microbial residues in different forest biomes remains unclear. Here, we investigated the effects of six/seven-year N additions on microbial residues (amino sugar biomarkers) in eight forests from tropical to boreal zone in eastern China. Our results showed a minor change in the soil microbial residue concentrations but a significant change in the contribution of microbial residue-C to SOC after N addition. The contribution of fungal residue-C to SOC decreased under low N addition (50kgN ha-1 yr-1) in the tropical secondary forest (-19%), but increased under high N addition (100kgN ha-1 yr-1) in the temperate Korean pine mixed forest (+21%). The contribution of bacterial residue-C to SOC increased under the high N addition in the subtropical Castanopsis carlesii forest (+26%) and under the low N addition in the temperate birch forest (+38%), respectively. The responses of microbial residue-C in SOC to N addition depended on the changes in soil total N concentration and fungi to bacteria ratio under N addition and climate. Taken together, these findings provide the experimental evidence that N addition diversely regulates the formation and composition of microbial-derived C in SOC in forest ecosystems.

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.

Spatial variation and radiocesium flux of litterfall in hardwood-pine mixed forest and cedar plantations based on long-term monitoring data

Long-term monitoring revealed that radiocesium (137Cs) deposition that fall from the canopy with litterfall was characterized by forest types, seasonal change, and canopy closure (CC). The sum of autumn and spring 137Cs deposition values divided by the sum of summer and winter tended to have higher values in the cedar forest. The angle of view α when the correlation between the CC size and litterfall amount is strongest, was 5° or less in the young cedar forest, but varied in the hardwood–pine mixed forest. This indicates the spatial distribution of 137Cs deposition has heterogeneity and homogeneity in each forest.

Burning season and vegetation coverage influenced the community-level physiological profile of Mediterranean mixed-mesogean pine forest soils

Knowledge of forest soil ecology is necessary to assess vulnerability to disturbances, such as wildfires, and improve its microbial diversity and functional value. Soil microbiota play an important role in forest soil processes and are a key driver of postfire recovery, but they are very vulnerable to heat. According to future scenarios for climate and land-use change, fire regimes will undergo transformations in semiarid terrestrial ecosystems, mainly in the Mediterranean Basin. To develop tools for forest management in fire-prone areas, i.e., fire prevention, we assessed the impact of prescribed burnings on soil microorganisms in Mediterranean mixed pine forests. We hypothesised that low severity fire burns would not influence the functional diversity of soil microorganisms, although the burning season could influence that response due to seasonal variations in its vulnerability. We used the Biolog EcoPlate System to record soil biological indicators and assess the effect of the prescribed burning season (early or late season) on bacterial communities, including the soil–plant interphase. The soil microbiome response differed significantly according to vegetation coverage but prescribed burning season was not directly related. Burning increased the proportions of soil organic matter and soil organic carbon, and also promoted cation-exchange capacity and total phosphorus, which were higher following spring burns. Microbial richness and the Shannon–Weaver diversity index both showed a positive correlation with vegetation cover. However, microbial richness was triggered after burning uncovered patches of vegetation. We also noted differences in the usage pattern for the six substrate groups defined in our study: the use of carboxylic acids, amino acids and carbohydrates was higher in unburned plots and those subject to late burns, whereas amino acids did not predominate in early burn plots.

The response of the soil bacterial community and function to forest succession caused by forest disease

Abstract Forest succession is a key driver of plant communities and understanding succession is central to forest restoration. Currently, the information on the response of the microbial community to the forest succession process, however, is limited. In the present study, we investigated the dynamics of the soil bacterial community in three forest types undergoing succession caused by pine wilt disease, representing the initial pine forest, gradual mixed pine and broadleaved forest, and eventual broadleaved forest, using Illumina MiSeq coupled with Functional Annotation of Prokaryotic Taxa (FAPROTAX) analysis. The results showed that the soil pH, contents of soil organic carbon (SOC) and soil total nitrogen (TN) increased after the occurrence of initial succession and differed among the forest sites. The mixed pine forest had significantly higher bacteria biomass (p &lt; 0.05), whereas, the total microbial biomass did not differ during the succession. The bacterial community diversity and richness increased significantly following the succession process (p &lt; 0.05). Proteobacteria, Actinobacteria, Acidobacteria and Bacteroidetes were the dominant phyla across the succession, in which the abundance of Bacteroidetes significantly increased (p &lt; 0.05), whereas, Planctomycetes, WPS‐2 and Burkholder decreased in abundance after succession occurred (p &lt; 0.05). The three forests formed distinct bacterial community structures during the succession (p &lt; 0.05), whereas, only two functional structures were clustered, in which the mixed and pure broadleaved forest did not differ. The dominant functional groups involved in the C cycle in the initial pure pine forest were replaced gradually by the groups involved in N and S cycles following the subsequent succession. The soil pH, soil TN and SOC were the most important factors affecting the bacterial community and functional structures during the succession. These results indicate that the bacterial community and function shift drastically in the early stages of succession, which reflects the changes in ecological environment caused by succession. The findings provide useful information to better understand the response of microbes to natural forest disturbance and highlight the importance of microbes during forest succession. A free Plain Language Summary can be found within the Supporting Information of this article.

Tree Species Structure, Composition and Regeneration in Van Panchayat Forests of Kumaun Himalaya, India

Present investigation was carried out to assess the structure, composition and regeneration of tree species along the altitudinal gradients of van panchayat (VP) forests in Kumaun Himalaya. The objective ofpresent study was to assess the VP forests in the context ofexisted disturbance level based on tree canopy cover, density, collection and lopping pressure in each selected VP forest. The density of trees, saplings and seedlings was 747-910, 507-1290 and 1553- 6660 ind.ha' in sal, 443-683, 137-207 and 1003-8843 ind.ha ' in pine and 773-873, 237-937 and 1193-1233 ind.ha ' in oak mixed VP forests, respectively. The sal mixed (site-1) and oak mixed (site-5) VP forests had shown good regeneration. The teak mixed (site-2), pine mixed (site-3 and site-4) and oak mixed (site-6) VP forests had depicted the fairregeneration, it showed that the existed seedlings were unable to shift in the higher class i.e. sapling stage. The girth class structure in site-1 and site-5 VP forests had clearly indicated good regeneration potential. In contrast, site-3 VP forest had depicted the fair regeneration because ofanthropogenic disturbance resulted change in the structure of VP forest. Thus it is very imperative to upgrade the management strategies of VP forests so that these forests could be conserved and managed in ajudicious and sustainable ways and also increase the active participation of villagers for conservation, management and efficient use of forest tree resources.