Gmelinii Plantation Research Articles

Niches, interspecific associations, and community stability of main understory regeneration species after understory removal in temperate forests.

Understory removal is frequently used to relieve the renewal pressure on trees and promote the growth capability of trees for maintaining community stability, while the lack of previous study on temperate forests limits our assessment of the effectiveness of this essential management measurement. In this study, we calculated the niche characteristics and interspecific association of main understory species and community stability in temperate forests [original broad-leaved Korean pine forest (BKF), Betula platyphylla secondary forest (BF), and Larix gmelinii plantation (LF)] after understory removal for characterizing the resource utilization capacity of the regeneration trees. During the restoration stage, the niche breadth of understory plants with similar habits varied across stands and layers; regeneration tree species with heliophile and semishade occupied a larger niche in BKF and LF, while it was the opposite in LF. Niche overlap among heliophile regeneration trees increased in both BKF and BF, but not in LF. The interspecific association among main species revealed that the distribution of each species was independent and the interspecific association was loose and it varied in different forests and different light-demanding species with regeneration trees. The stability of shrub communities in BF and LF improved whereas that of BKF declined, while that of the herb communities of corresponding forests showed the opposite state. Our study demonstrated that the effectiveness of understory removal depends on species' ecological habits, which enhances the renewal and resource utilization capacity of regeneration tree species in temperate forests and shrub community stability in BF and LF.

Short-term responses of root traits and carbon exudation to drought in a Larix gmelinii plantation

Short-term responses of root traits and carbon exudation to drought in a Larix gmelinii plantation

Assessment of soil quality under different land use types in the rocky mountain area of northern Hebei Province, China.

To assess the variations of soil quality among land use types and with altitude in the rocky mountain area of northern Hebei Province is critical for preventing further human-induced degradation of land and vegetation, and for formulating a strategic plan on vegetation restoration after the Beijing Winter Olympics. Taking Betula platyphylla natural forest, Larix gmelinii plantation, natural grassland and abandoned cropland as research objects, 13 soil physicochemical indices (e.g., soil bulk density, porosity and soil nutrient content) were measured to compare soil quality among land use types. The results showed that soil quality presented the trend as B. platyphylla natural forest > natural grassland > L. gmelinii plantation > abandoned cropland. B. platyphylla natural forest had the best soil quality due to high total nitrogen (3.24 ±1.42 g·kg-1) and phosphorus (0.59±0.10 g·kg-1) contents, suggesting that long-term soil nutrient accumulation played an important role in preventing soil degradation. Soil quality in natural grassland was lower than that in B. platyphylla natural forest, due to topographic factors and coarse soil fraction. Soil physical properties in L. gmelinii plantation had been substantially improved after 40 years restoration, as indicated by significant reductions in soil gravel fraction, while soil nutrient contents changed little. The low soil quality in abandoned cropland was attributable to low vegetation coverage and intense human activities in the low-altitude area. Driven by soil total nitrogen, soil quality under the four land use types increased with altitude, and peaked at about 1700 m. We suggested that enclosure and ecological restoration measures should be strengthened in ecologically-fragile, low-altitude areas, taking sustainable development into consideration for high-density stands and promoting plantations to adapt to environmental change.

Understory plant diversity and soil physicochemical properties of Pinus tabuliformis artificial water conservation forests in the upper reaches of Miyun Reservoir, China

We examined the characteristics of understory plant diversity and physicochemical properties and analyzed the correlation between understory plant diversity and soil factors across four Pinus tabuliformis artificial water conservation forests (P. tabuliformis × Larix gmelinii plantation, P. tabuliformis × Quercus mongolica plantation, P. tabuliformis × Armeniaca sibirica plantation, and P. tabuliformis plantation) in Fengning County, upstream of Miyun reservoir. The results showed that the composition and structure of understory community of the four forests were significantly different. The understory community in the P. tabuliformis × A. sibirica plantation was the richest in species composition, with Spiraea salicifolia, Ostryopsis davidiana, and Carex lanceolata as the main dominant species. In terms of species richness, Simpson index, Shannon diversity index, and Pielou index, plant diversity in the P. tabuliformis × A. sibirica plantation was the highest. Species diversity in the shrub layer and the herb layer was the highest in the P. tabuliformis × Q. mongolica plantation and the P. tabuliformis × Q. mongolica plantation, respectively. All physical and chemical indicators except total phosphorus differed significantly among the four forests. Soil physical and chemical properties of the P. tabuliformis × A. sibirica plantation were the best overall, and that in the P. tabuliformis × Q. mongolica plantation was the worst. Soil capillary porosity, pH, and organic matter were the main factors affecting species diversity in the shrub layer, while soil pH and capillary moisture capacity were the main factors affecting plant species diversity in the herb layer. The construction of P. tabuliformis × A. sibirica plantation was more conducive to increasing the diversity of understory plants and promoting soil improvement. Soil pH, organic matter, capillary porosity, and capillary moisture capacity were the dominant soil factors affecting the diversity of understory plants in the study area.

The Effects of Shrub Removal on Soil Microbial Communities in Primary Forest, Secondary Forest and Plantation Forest on Changbai Mountain.

Shrub removal is a common management method in forest ecosystems, but comparatively little is known regarding the effects of shrub removal on soil microbial communities among primary forest, secondary forest, and plantation forests in temperate forests, which limits our accurate assessment of sustainable management of understory vegetation removal. Given this, we used a long-term operation experiment across a contrasting mixed broadleaved-Pinus koraiensis forest, Betula platyphylla forest, and Larix gmelinii plantation forest to explore the variations of soil properties and microbial community after 5years of shrub removal on Changbai Mountain, as well as the contribution of the soil properties and understory plant diversity to the soil microbial community. The results demonstrated that shrub removal could significantly alter soil SWC and TN, TP, and AP contents of the L. gmelinii, as well as N/P of B. platyphylla. Moreover, shrub removal also clearly improved soil bacterial Pielou_e index and Simpson index of mixed broadleaved-P. koraiensis and soil bacterial Simpson index of L. gmelinii, and decreased soil fungal Pielou_eindex and Shannon index of L. gmelinii and soil bacterial Pielou_e index and soil fungal Shannon index of B. platyphylla. Identically, shrub removal notably altered the soil bacterial community composition. Soil characteristics and understory plant diversity accounted for 48.02% and 26.88%, and 45.88% and 27.57% of the variance in the bacterial and fungal community composition, respectively. This study aimed to provide an important scientific basis for the restoration and sustainable management of temperate forests in the Changbai Mountain region.

Differential Responses of Soil Bacterial and Fungal Community to Short-Term Crop Tree Management in a Larix gmelinii Plantation

Crop tree management (CTM) is a widely applicable silviculture technology that is used to improve the performance of individual trees. However, only little information is available about the effects of the CTM regime on the soil microbial community structure. We conducted a study to explore the effects of short-term (five years) CTM on the soil bacterial and fungal diversity, community composition, and structure in the 0–10 cm soil layer in a Larix gmelinii (Rupr.) Kuzen. plantation. We set out to investigate the differential response of bacterial and fungal communities to variations in soil properties mediated by short-term CTM. Compared with the control plots, the soil microbial biomass carbon and microbial biomass nitrogen in CTM increased significantly by 64.2% and 32.3%, respectively. CTM significantly promoted the content of soil organic carbon, dissolved organic carbon, and nitrate nitrogen, and reduced the content of dissolved organic nitrogen. CTM changed the Shannon and Simpson indices of soil fungi to a remarkable extent but had little effect on the α diversity of bacterial communities. The bacterial β diversity was more sensitive to CTM than fungi. The relative abundance of Verrucomicrobiae (the dominant class of soil bacteria) in CTM was significantly increased by 78.2%, while the relative abundance of Agaricomycetes (dominant class for soil fungi) was reduced by 43.3%. We observed a significantly increased number of unique OTUs for soil fungi in the CTM plots. Redundancy analysis showed that dissolved organic carbon, soil moisture, and total phosphorus content significantly affected the composition of bacterial communities, while soil dissolved organic nitrogen, C/N, and total phosphorus drove the high variation in fungal community composition. Overall, our results emphasize the divergent response of soil bacterial and fungal communities in Larix gmelinii plantations to short-term CTM. We must pay more attention to the functional role of soil microbiota in future forest management.

Leaf hydraulic traits of larch and ash trees in response to long-term nitrogen addition in northeastern China

Abstract Aims Atmospheric nitrogen (N) deposition influences tree hydraulic architecture and thus the growth and survival; but the responses of leaf hydraulic traits remain uncertain, and may vary with species or plant functional types. Methods We used the 16-year N addition experiment (10 g N m−2 year−1) on Fraxinus mandshurica (ash, broadleaf angiosperm) and Larix gmelinii (larch, conifer gymnosperm) plantations in northeastern China and examined the effect of N addition on their leaf hydraulics. We measured the leaf pressure–volume traits by the bench drying method and quantified the maximum leaf hydraulic conductance (Kleaf_max) and resistance to embolism (P50leaf) by the timed rehydration method. Important Findings Larch had higher Kleaf_max and stronger drought tolerance (i.e., lower relative water content at turgor loss point (RWCtlp) and modulus of elasticity (ε), and more negative P50leaf) than ash. N addition increased the leaf osmotic potential at turgor loss (πtlp) and full turgor (π0), and leaf capacitance (Cleaf_mass) for ash but not for larch, indicating that ash is more sensitive to N addition. N addition consistently increased Kleaf_max and P50leaf values for both species. πtlp and π0 were positively while Cleaf_mass was negatively correlated with leaf density (LD) for ash. Kleaf_max was positively but P50leaf was negatively related with LD for larch. There were negative relationships between Kleaf_max and P50leaf for both species. Overall, our findings suggest that long-term N addition decreases the leaf drought tolerance for these two important tree species, which improve the understanding of the tree hydraulic performance under N deposition.

Growth variations of Dahurian larch plantations across northeast China: Understanding the effects of temperature and precipitation

Climate change is affecting the growth and distribution of trees in the Chinese boreal forest. Such changes in China, the southern terminus of the extensive Eurasian boreal forests, reflect on the changes that could occur further north under a warming climate. Most studies have found that tree growth increases with increasing temperature and precipitation in boreal forests, but there is little observational evidence of the climate thresholds that might slow these growth rates at the more extreme temperatures which are predicted to occur under future global warming. Here, we examine growth responses of this dominant boreal tree species (Larix gmelinii) to climate based on the data from plantation sample plots across a broad region (40° 51′–52° 58′N, 118° 12′E−133° 42′E) in northeast China. From statistically significant fits to quadratic equations, temperature and precipitation are the important climatic factors determining tree growth in L. gmelinii plantations at two age classes (<10 year and 10–30 year-old stands). The maximum rates of tree height and diameter at breast height (DBH) were about 0.53 m/year and 0.46 cm/year at <10 year stands, and about 0.63 m/year and 0.60 cm/year at 10–30 year stands, respectively. For stands with the highest values of mean annual increment (MAI), the corresponding optimal mean annual temperature (MATopt) focused between 0.66 °C and 1.57 °C. The optimal mean annual precipitation (MAPopt) between 663 mm and 708 mm produced the maximal growth increments. With mean annual temperature of −2.4 °C and precipitation of 470 mm averaged over 1954–2005 in Chinese boreal forest region as baseline, we conservatively estimated that trees in Chinese boreal forest appear to have higher growth potentials with the maximum temperature increase of 3.6 °C and precipitation increase of 40%.

A study of emissions and marker gases from smouldering combustion in Larix gmelinii plantations of the Daxing’an Mountains

Underground fires are characterized by smouldering combustion with a slow rate of spread rate and without flames. Although smouldering combustion releases large amounts of gaseous pollutants, it is difficult to discover by today’s forest fire monitoring technologies. Carbon monoxide (CO), nitrogen oxides (NOx) and sulfur dioxide (SO2) were identified as high concentration marker gases of smouldering combustion-easily-be monitored. According to a two-way ANOVA, combustion time had a significant impact on CO and NOx emissions; smoldering -depth also had a significant impact on NOx emissions but not on CO emissions. Gas emission equations were established by multiple linear regression, Cco = 156.989 − 16.626 t and CNOx = 3.637 − 0.252 t − 0.039 h.

Effects of climate change on tree water use efficiency, nitrogen availability and growth in boreal forest of northern China

Climate change, particularly rising atmospheric carbon dioxide (CO2) concentration, can influence carbon (C) and nitrogen cycling (N) in different forest ecosystems. The major objective of this study was to quantify the long-term physiological and tree growth trends of Larix gmelinii plantation in a boreal environment of northern China in response to elevated atmospheric CO2 concentration and other climatic conditions. Tree rings were extracted from four Larix gmelinii sample trees, located in a boreal plantation forest of Mohe City, Heilongjiang Province, China. Tree rings were measured with a mean annual basal area increment (BAI), while tree ring stable C isotope composition (δ13C) and N isotopic composition (δ15N) as well as total C and N concentration were measured on mass spectrometer at 3-year intervals. Tree intrinsic water use efficiency (iWUE) was calculated using tree rings δ13C and atmospheric δ13C data. Multiple regression analysis was used to quantify the BAI and WUE relationships with atmospheric CO2 concentration, temperature, precipitation and humidity of the study site. The results showed a quadratically decrease in relative humidity over the past 60 years with rising temperature, indicating the initial increasing water availability, which is peaked, but increasing water limitation thereafter. Tree iWUE continued to increase as atmospheric CO2 concentration (Ca) increased. Tree BAI showed a quadratic relationship with atmospheric CO2 (Ca), increasing initially, but peaking at the critical threshold of 352.5 ppm or in 1986, and decreasing with the Ca thereafter. Tree ring δ15N, an index of N availability, also responded non-linearly to the rising Ca, increasing initially with the Ca, but peaking at the critical Ca of 348–367 ppm and decreasing thereafter with the rising Ca, indicating the decreasing N availability in the last 20–30 years after the Ca continued to rise. The iWUE of Larix gmelinii continued to increase under rising Ca, but this increased iWUE did not translate into tree growth consistently due to increasing water and N limitation in the boreal forest ecosystems under intensifying climate change in the last 20–30 years.

Soil quality assessment of vegetation restoration after a large forest fire in Daxing’anling, northeast China

Forest fires significantly change soil function and quality. Finding an effective way to accelerate the restoration of soil quality after forest fires is a major issue. This study investigated the soil quality index (SQI) during vegetation restoration after a fire in a Larix gmelinii plantation, throughout different restoration years. Fifteen physical, chemical, and biological properties of soil were examined using principal component analysis, and soil quality was assessed by SQI. The results revealed that soil physical properties, chemical properties, and enzyme activities showed the most improvement after 24 yr of restoration. Soil microbial biomass carbon content and microbial biomass nitrogen content increased with restoration years. Soil bulk density, microbial biomass nitrogen, sucrase, and catalase were retained in the minimum data set. After 24 yr of restoration, SQI was the highest, with a value of 0.52, followed by natural restoration, 21, 13, and 16 yr; the SQI after 3 yr of restoration was the lowest, with a value of 0.26. Artificial regeneration accelerated the recovery of soil quality after 24 yr. Soil quality should be monitored continuously in the study area.

Soil phosphorus forms and phosphorus solubilizing bacteria distribution after restoration from seriously burning in Greater Khingan Mountain areas, China

To understand the contents of various phosphorus forms, phosphorus solubilizing bacte-rial community structure and the relationship between them in soils after restoration from the seriously burning, we collected soil samples from artificial restoration (Pinus sylvestris var. mongolica plantation, Larix gmelinii plantation), artificial accelerated natural restoration (secondary forest) and natural restoration (natural secondary forest) stands in Greater Khingan Mountain area. Using methods of Sui et al. modified from Hedley phosphorus fractionation, we measured the contents of different phosphorus forms in rhizosphere soil and bulk soil (0-10, 10-20 cm). Abundances of phosphorus solubilizing bacteria were quantified by high-throughput sequencing method. The results showed that the contents of H2O-Pi, NaHCO3-Pi and NaHCO3-Poin 0-10 cm bulk soil and NaHCO3-Po in rhizosphere soil followed the order of L. gmelinii plantation : P. sylvestris var. mongolica plantation : natural secondary forest : secondary forest. The contents of H2O-Pi, NaHCO3-Pi, NaHCO3-Po in 10-20 cm bulk soil and H2O-Pi, NaHCO3-Pi in rhizosphere soil followed the order of L. gmelinii plantation : P. sylvestris var. mongolica plantation : secondary forest : natural secondary forest. The ratios of contents of H2O-Pi, NaHCO3-Pi and NaHCO3-Po in rhizosphere to those in bulk soil (R/S) were higher than 1 in all forest stands. The moderately labile NaOH-P included NaOH-Pi and NaOH-Po. The content of NaOH-P was in order of L. gmelinii plantation : natural secondary forest : secondary forest : P. sylvestris var. mongolica plantation in 0-10 cm layer of bulk and rhizosphere soil, and ranked as L. gmelinii plantation : P. sylvestris var. mongolica plantation : secondary forest : natural secondary forest in 10-20 cm layer of bulk soil. There was rhizosphere effect of NaOH-P in the soil. The stable HCl-P included HCl-Pi and HCl-Po. The content of HCl-P followed the order of L. gmelinii plantation : natural secondary forest : P. sylvestris var. mongolica plantation : secondary forest in 0-10 cm layer of bulk soil,and ranked as L. gmelinii plantation : P. sylvestris var. mongolica plantation : natural secondary forest : secondary forest in the 10-20 cm layer. The content of residual-P in the soil was not sensitive to restoration methods. Bradyrhizobium, Streptomyces, Burkholderia and Bacillus were the main phosphorus solubilizing bacteria across all forest stands. The abundances of phosphorus solubilizing bacteria in soil of L. gmelinii plantation and P. sylvestris var. mongolica plantation were significantly higher than that of secondary forest and natural secondary forest. Results of redundancy analysis showed that the correlation between phosphorus solubilizing bacteria and various phosphorus forms was different. Our results showed that artificial afforestation was more conducive in improving the availability of phosphorus in soil and the abundance of phosphorus solubilizing bacteria.

Improved root turnover assessment using field scanning rhizotrons with branch order analysis

AbstractRoot turnover is a key process contributing to soil carbon storage, nutrient cycling, and other ecosystem functions. However, quantifying root turnover rates remains highly uncertain and methodologically challenging. Field rhizotrons were employed to quantify root turnover times using median longevities of five branching orders in a Larix gmelinii plantation. Root images were recorded by scanning the rhizotron windows at a monthly interval during four growing seasons. Root demographic data and branching orders were obtained by analyzing these images using Rootfly software coupled with manual mouse‐tracing of individual roots. Root longevities and turnover estimates were calculated using these data. Roots of different branching orders showed significantly different turnover times. The mean turnover times of the first‐order roots and second‐order roots were 284 and 994 d, respectively. Roots of higher branching orders (third to fifth orders) remained alive at the end of the 4‐yr experimental period, indicating much longer turnover times than the duration of the experiment. Root turnover times increased exponentially with branching orders. Further analysis of these data suggested that root branching orders combined with sampling biases, timing of root cohorts, and longevity distribution patterns crucially influenced root turnover times. The method of combining field glass rhizotrons with electronic scanning permits quantification of root turnover for five branching orders in a temperate forest. The overall result empirically demonstrates the crucial role of branching orders for accurately quantifying root turnover times.

Effects of Long-term Nitrogen Addition on Soil Enzymes in Larix gmelinii Plantation in Northeast China

Effects of Long-term Nitrogen Addition on Soil Enzymes in Larix gmelinii Plantation in Northeast China

Effects of different land use patterns on the soil microbial community diversity in montane region of eastern Liaoning Province, China.

An experiment was conducted to examine the differences of soil microbial diversity across different land use patterns in montane region of eastern Liaoning Province, China. The relationships between soil physicochemical properties and soil microbial diversity in five different land use types, including Quercus mongolic forest, shrubland, Larix gmelinii plantation, Pinus koraiensis plantation, and Zea mays cropland were analyzed by Biolog-Eco method. The results showed that both soil total C and N contents were the highest in the Q. mongolica forest, which were 57.74 and 4.40 g·kg-1, followed by shrubland, but only 17.46 and 1.31 g·kg-1 in the Z. mays cropland, respectively. There were significant differences in microbial utilization rate of different land use types. The carbon utilization capacity by soil microbial communities was following the order of Q. mongolica forest > shrubland > L. gmelinii plantation > P. koraiensis plantation > Z. mays cropland, indicating that soil microbial metabolism and activity in Z. mays cropland were the lowest. The Shannon diversity index (2.997), Simpson diversity index (0.942) and McIntosh diversity index (5.256) of soil microbial community in the Z. mays cropland were significantly lower than those in other ecosystems. The average absorbance value (AWCD) was associated with Simpson diversity index and McIntosh diversity index. Esters, alcohols and amines were the primary carbon sources for the differentiation, which might be due to a joint action of many factors such as litter, soil nutrients, and specific soil microorganisms. The soil nutrient and soil microbial community diversity in forest land after reclamation sharply decreased, causing the loss of soil fertility and productivity. The region should keep the Q. mongolica forest, which could help restore soil fertility.

Soil microbial biomass, phosphatase and their relationships with phosphorus turnover under mixed inorganic and organic nitrogen addition in a Larix gmelinii plantation

Atmospheric nitrogen (N) deposition can affect soil microbial biomass, phosphatase activity, and the concentrations of organic phosphorus (P), inorganic P and available P, but the changes in soil microbial biomass under mixed inorganic and organic N addition and their relationships with soil P turnover in forest ecosystems are not fully understood. In this study, a simulated N deposition experiment was conducted in a Larix gmelinii plantation in Northeastern China to investigate the variation of soil microbial biomass, phosphatase activity, P forms and available P concentrations as well as the relationships between these features. The experiment was arranged in a randomized block design with three replications for each treatment, including the control (no N addition, CK), total inorganic N (NH4NO3, TIN), mixed inorganic and organic N (inorganic N and organic N in the ratio of 7:3, ION), and total organic N (urea and glycine 1:1, TON). The results indicated that there was a significant difference in the response of soil biochemical characteristics to different types of N addition. Soil total microbial biomass, the biomass of bacteria and actinomycetes, alkaline phosphomonoesterase (AlP) activity, as well as oxalate-extracted aluminum (Al), cMonoesters, cDiesters and orthophosphate concentrations were significantly increased by the addition of mixed inorganic and organic N, whereas they were not affected by single inorganic or organic N addition. Compared to the CK treatment, the increase in soil microbial biomass and Al oxides concentrations under ION treatment significantly increased soil cMonoesters and cDiesters concentrations, and the increased bacterial biomass contributed to the increase of soil AlP activity. Moreover, the ION treatment also significantly increased soil total P concentration and enhanced microbial immobilization of P compared to the CK treatment. However, there was no significant difference in available P concentration between the ION treatment and other treatments, which could be attributed to increased orthophosphate concentration under the ION treatment. Overall, the findings suggest that bacteria and AlP can play important roles in maintaining soil P availability by accelerating P turnover under conditions of increased atmospheric N deposition in a Larix gmelinii plantation.

Vertical variation in stoichiometric relationships of soil carbon, nitrogen and phosphorus in five forest types in the Maoershan region, Northeast China.

Five forests under diverse site conditions but under identical climate in the Maoershan region of Northeast China were sampled for measuring contents of soil carbon (C), nitrogen (N), and phosphorus (P), soil bulk density, and soil thickness by soil profile horizons. The stands included two plantations (i.e., Pinus koraiensis and Larix gmelinii plantations) and three broadleaved forests (i.e., Quercus mongolica stand, Populus davidiana Betula platyphylla mixed stand, and hardwood stand). Our aim was to examine vertical distribution of the content, density, and stoichio metry of soil C, N and P for the five forest types. The results showed that the contents and densities of soil C, N and P differed significantly among the forest types, with the maxima of the soil C and N at both O and A horizons occurring in the hardwood stand. The contents of C and N decreased significantly with increasing soil depth in all the stands. P content decreased significantly only in the broadleaved stands, and P content had no significant difference among different soil layers in the coniferous stands. The soil C/N at the A horizon, N/P at the O horizon, and the C/P at A and B horizons were significantly different among the forest types. The soil C and N linearly correlated significantly across all the forest types without significant differences in the slopes and intercepts, and the soil N and P, or the soil C and P correlated significantly only in the broadleaved stands. This result suggested that the C-N coupling relationship tended to converge across the forest types, and the N-P and C-P relationships varied with forest types.

Newly sequestrated soil organic carbon varies with soil depth and tree species in three forest plantations from northeastern China

To evaluate and improve the ecological benefit of forestation programs, post-forestation estimations of newly sequestrated soil organic carbon (SOC) are necessary. Here, we collected soil samples from three plantations in northeast China and used 13C natural abundance to measure the amount of SOC sequestrated since 1998. Newly sequestrated SOC decreased with the increasing soil depth in the Larix gmelinii plantation, but increased with soil depth in the Populus trichocarpa plantation. In contrast, newly sequestrated SOC in the Armeniaca sibirica plantation peaked at a soil depth of 30–40cm. With increasing distance from the tree trunk, average newly sequestrated SOC gradually decreased in the L. gmelinii plantation, did not vary in the P. trichocarpa plantation, and exhibited a gentle unimodal curve in the A. sibirica plantation. Overall, the average density of newly sequestrated SOC in the L. gmelinii, P. trichocarpa, and A. sibirica plantations at a soil depth of 0–50cm was 0.60, 0.70, and 0.61gcm−3, respectively. Determination of δ15N and the C/N ratio provided evidence to support the hypothesis that newly sequestrated SOC was primarily regulated by the root-microbial system. Soil depth and tree species should be taken into account when estimating soil carbon sequestration in future studies.

Effects of continuous nitrogen addition on microbial properties and soil organic matter in a Larix gmelinii plantation in China

Continuous increases in anthropogenic nitrogen (N) deposition are likely to change soil microbial properties, and ultimately to affect soil carbon (C) storage. Temperate plantation forests play key roles in C sequestration, yet mechanisms underlying the influences of N deposition on soil organic matter accumulation are poorly understood. This study assessed the effect of N addition on soil microbial properties and soil organic matter distribution in a larch (Larix gmelinii) plantation. In a 9-year experiment in the plantation, N was applied at 100 kg N ha−1 a−1 to study the effects on soil C and N mineralization, microbial biomass, enzyme activity, and C and N in soil organic matter density fractions, and organic matter chemistry. The results showed that N addition had no influence on C and N contents in whole soil. However, soil C in different fractions responded to N addition differently. Soil C in light fractions did not change with N addition, while soil C in heavy fractions increased significantly. These results suggested that more soil C in heavy fractions was stabilized in the N-treated soils. However, microbial biomass C and N and phenol oxidase activity decreased in the N-treated soils and thus soil C increased in heavy fractions. Although N addition reduced microbial biomass and phenol oxidase activity, it had little effect on soil C mineralization, hydrolytic enzyme activities, δ13C value in soil and C–H stretch, carboxylates and amides, and C–O stretch in soil organic matter chemistry measured by Fourier transform infrared spectra. We conclude that N addition (1) altered microbial biomass and activity without affecting soil C in light fractions and (2) resulted in an increase in soil C in heavy fractions and that this increase was controlled by phenol oxidase activity and soil N availability.

6种温带森林凋落量年际及年内动态

PDF HTML阅读 XML下载 导出引用 引用提醒 6种温带森林凋落量年际及年内动态 DOI: 10.5846/stxb201509091861 作者: 作者单位: 东北林业大学生态研究中心,东北林业大学生态研究中心,东北林业大学生态研究中心 作者简介: 通讯作者: 中图分类号: 基金项目: 教育部长江学者和创新团队发展计划（IRT15R09）；中央高校基本科研业务费专项资金项目（2572014AA11） Inter- and intra-annual dynamics in litter production for six temperate forests Author: Affiliation: Center for Ecological Research,Northeast Forestry University,Center for Ecological Research,Northeast Forestry University,Center for Ecological Research,Northeast Forestry University 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:森林凋落物量及其组分因生态系统结构特征和环境变化而表现出明显的时间动态，从而影响森林生态系统物质循环和生态服务功能。连续6年观测帽儿山地区6种温带森林凋落物量及组份的时间动态、温度和降雨量等气象因子，旨在深入了解该地区森林生态系统的物质循环过程及调控因子。结果表明：6种森林的年落凋落量差异显著，平均值依次为：蒙古栎林（4.60 t/hm2） > 杂木林（4.21 t/hm2） > 硬阔叶林（4.03 t/hm2） > 红松林（3.95 t/hm2） > 杨桦林（3.89 t/hm2） > 落叶松林（3.85 t/hm2）。各森林年凋落量的年际变化表现为“升高-降低”交替波动模式，但总体上呈上升趋势。凋落物各组份的年际变化不同，枝凋落量变化较为稳定；叶凋落量与凋落总量一致，升高-降低波动明显；繁殖器官及其他凋落量随林龄增加而增加。各森林凋落物量的年内变化呈单峰曲线波动，最大值出现时间因林型而异。枝凋落量在年内表现为双峰曲线模式波动；叶凋落量年内呈单峰曲线模式波动，并与凋落总量年内动态一致；繁殖器官与其他凋落量年内动态波动平缓，无明显凋落峰值。降雨量显著影响年凋落物量（P < 0.05），分别解释了凋落总量、叶凋落量90%、87%变化。平均温度、积温和总降雨量显著影响凋落量年内动态，总降雨量的影响作用最为突出。因此，除林分自身的生物学特性外，降雨是影响该温带森林凋落量年内、年际动态的重要因素。 Abstract:Litter production and its composition in temperate forests show seasonal dynamics due to changes in the ecosystem structure and environment, which directly affect the nutrient cycling and ecological services in the ecosystems. In this study, we investigated seasonal dynamics in the litter production and its composition for six forest types in Maoershan region for six continuous years in order to reveal the factors driving the inter- and intra-annual variability of the litter production. The results showed that annual litterfall (t/hm2) decreased in the order of:Quercus mongolica stand (4.60) > mixed deciduous stand (4.21) > hardwood stand (4.03) > Pinus koraiensis plantation (3.95) > Populus-Betula stand (3.89) > Larix gmelinii plantation (3.85). There was a significant difference in total litterfall among the six stands. The litter production fluctuated interannually and showed an overall increasing tendency. The interannual variation in the litter composition depended upon its compoents:the litter production of woody tissues was relatively stable; that of foliages was consistent with the total litter production; and that of reproductive tissues and others increased with stand age. The production of total litter showed a mono-peak seasonal pattern for all the stands, and the occurrence of the peak varied with forest type. The litter production of woody tissues displayed a bimodal seasonal course; that of foliages was a mono-peak curve; and that of reproductive tissues and others was relatively stable intra-annually. Total rainfall significantly influenced the inter-annual litter production (P < 0.05), and explained 90% and 87% of the variability in the total litter production and the production of woody tissues, respectively. Mean temperature, cumulative temperature and total rainfall significantly affected intra-annual variability in litter production, among which the effect of total rainfall was dominant. In conclusion, rainfall, in addition to the biological characteristics of the forests, was a key factor driving the inter- and intra-annual dynamics in litter productions. 参考文献 相似文献 引证文献