Fine Root Dynamics Research Articles

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.

Gap Size in Hyrcanian Forest Affects the Lignin and N Concentrations of the Oriental Beech (Fagus orientalis Lipsky) Fine Roots but Does Not Change Their Morphological Traits in the Medium Term

Research Highlights: Fine roots play an important role in plant growth as well as in carbon (C) and nutrient cycling in terrestrial ecosystems. Gaining a wider knowledge of their dynamics under forest gap opening would improve our understanding of soil carbon input and below-ground carbon stock accumulation. Single-tree selection is increasingly recognized as an alternative regime of selection cutting sustaining biodiversity and carbon stock, along with timber production, among ecosystem functions. However, the fine root response in terms of morphological and chemical composition to the resulting harvest-created gaps remains unclear. Background and Objectives: This paper investigates the effect in the medium term (i.e., 6 years after logging) of differently sized harvest-created gaps on fine root dynamics and chemical composition. Materials and Methods: A total of 15 differently sized gaps (86.05–350.7 m2) and the adjacent 20 m distant closed canopies (control) were selected in a temperate Fagus orientalis forest (Hyrcanian region, Iran). Eight soil cores were collected at the cardinal points of the gap edge, including four facing the gap area—the same at the adjacent intact forest. Results: For the selected edge trees, the different size of gaps, the core position, and the tree orientation did not affect the investigated morphological traits, except for the slightly higher specific root length (SRL) for the larger fine root fraction (1–2 mm) in the side facing the gap area. Differently, the investigated chemical traits such as N concentration and cellulose:lignin ratio significantly increased with increasing gap size, the opposite for C:N ratio and lignin. Moreover, N concentration and C:N significantly decreased and increased with the fine root diameter, respectively. Conclusions: This work highlighted that, in the medium term and within the adopted size range, artificial gap opening derived from single-tree selection practice affected the chemistry rather than the biomass and morphology of gap-facing fine roots of edge trees. The medium term of six years after gap creation might have been long enough for the recovery of the fine root standing biomass to the pre-harvest condition, particularly near the stem of edge trees. A clear size threshold did not come out; nevertheless, 300 m2 may be considered a possible cut-off determining a marked change in the responses of fine roots.

Influence of Nepalese alder on soil physico-chemical properties and fine root dynamics in white oak forests in the central Himalaya, India

The main objective of the study was to investigate influence of Nepalese alder (Alnus nepalensis D. Don) on fine root biomass (diameter ≤ 2 mm) dynamics and the physical and chemical properties of the soil in white oak (Quercus leucotrichophora A. Camus) forests. Five representative stands of each oak mixed alder (OMA) and oak without alder (OWA) were selected along the stand development gradient in the Indian central Himalaya. Fine root and soil samples from of 0–10 cm, 10–20 cm, and 20–30 cm depths were collected using soil core method. Soil physical and chemical properties and monthly variations in fine root dynamics (biomass distribution and decomposition) were analyzed. Fine root decomposition was studied by using the litterbag technique. Redundancy and correlation analyses were performed to evaluate the relationship between fine root dynamics, stands, and tree total basal area and soil properties. Both the fine root biomass and production of Q. leucotrichophora were significantly (P < 0.05) higher for oak without alder stands than oak mixed alder stands. Fine root biomass, production, and turnover rate of A. nepalensis were significantly (P < 0.05) higher than Q. leucotrichophora in oak mixed alder stands. Within the investigated soil profile, in all the sites, maximum fine root biomass and production were found in the upper (0–10 cm) soil depths. The analyses revealed clear differences in all the measured soil physical and chemical properties and fine root traits in oak mixed alder and oak without alder stands. The soil organic carbon (SOC), total nitrogen (TN) contents, and soil C and N stocks were significantly (P < 0.05) higher in oak mixed alder stands than oak without alder stands while opposite trends were found for soil pH and bulk density (BD). Present findings reveal that improvement of the soil properties under oak mixed alder stands was significantly higher than the oak without alder stands. Fine root decomposition for A. nepalensis was significantly faster than Q. leucotrichophora. Q. leucotrichophora fine roots in OMA stands decomposed at significantly faster rates compared to OWA stands. Additionally, the present study suggests that variation, in fine root dynamics across the forest stands was not only positively correlated to the soil physical and chemical properties but also highly dependent on the forest stand characteristics.

Fine root dynamics and below- and above-ground carbon inputs into soil in boreal forests

Fine root dynamics and below- and above-ground carbon inputs into soil in boreal forests

Fine Roots Dynamics in Two Forest Strata of a Semi-Deciduous Forest in Northern Republic of Congo

The belowground biomass is represented by coarse and fine roots. Concentrated in the superficial horizons of the soil, the fine roots play a crucial role in the functioning of a forest ecosystem. However, studies on their dynamics in natural forests are almost non-existent in the Republic of Congo. Here, we estimated the biomass, production, turnover and fine root lifespan of two forest strata of a semi-deciduous forest: the Gilbertiodendron dewevrei (De Wild.) J. Léonard forest (GF) and the mixed forest (MF) of land. The ingrowth cores method was used to estimate the biomass, production, turnover and lifespan of fine roots. The results of this study revealed that the biomass, production and fine root turnover of the two forest strata studied significantly decreased with increasing soil depth, with an increase in lifespan. The annual fine root biomass of GF (2284.50 ± 37.62 and 1034.61 ± 14.52 ) was slightly lower than that of MF (2430.07 ± 40.68 and 1043.10 ± 11.75 ) in the 0-15 cm and 15-30 cm horizons, respectively. The annual production of fine roots from these latter horizons was respectively 1300.19 ± 32.17 and 539.18 ± 11.55 in GF and 1362.24 ± 39.59 and 492.95 ± 14.38 in the MF. Root turnover was higher in the GF (1.68 ± 0.05 and 1.35 ± 0.03 ) than in the MF (1.57 ± 0.05 and 1.13 ± 0.02 ). The lifespan of fine roots increased with the depth of the soil. The difference in fine root dynamics observed between the forest strata studied was influenced by the Evenness index and the above-ground biomass.

森林细根动态和形态对氮有效性增加响应的研究进展

森林细根动态和形态对氮有效性增加响应的研究进展

Fine Root and Soil Nitrogen Dynamics during Stand Development Following Shifting Agriculture in Northeast India

Nitrogen (N) dynamics during changes in land use patterns in tropical forests may profoundly affect fine root dynamics and nutrient cycling processes. Variations in fine root biomass and soil N dynamics were assessed in developing stands of increasing ages following shifting agriculture in Mizoram, Northeast India, and comparisons were made with a natural forest stand. Concentrations of soil available N (NH4-N and NO3-N) and the proportion of NH4-N in total available N increased with stand age. The N-mineralization rate also increased with stand age whilst the proportion of nitrification relative to ammonification declined during succession. Fine root biomass and N-mineralization increased, and available N decreased during the monsoon season while this pattern was reversed during the winter season. A greater proportion of fine roots were &lt;0.5 mm diameter in the younger sites, and turnover of fine roots was more rapid in the developing stands compared to the natural forest. Fine root biomass was correlated positively with N-mineralization rate and soil water content. Thus, it can be concluded that the fine root growth was aided by rapid N-mineralization, and both fine root growth and N-mineralization increase as stands redevelop following shifting cultivation disturbance.

Effect of snow removal on the fine root biomass, dynamics, and carbon and nitrogen concentrations of oak and dwarf bamboo, Sasa in eastern Hokkaido, Japan

ABSTRACT Fine root is a significant component in carbon (C) and nitrogen (N) dynamics in temperate forests. Winter processes affect plant growth and nutrient concentration, however, the effect of reduced snowpack on fine root remains unclear. Here, we conducted snow removal manipulation and investigated the fine root biomass and necromass, dynamics (production, mortality and disappearance) and the C and N concentrations of Quercus crispula (oak) and Sasa nipponica (Sasa), in mineral topsoil (0–10 cm) throughout 1 year. The effect of snow removal on the fine root biomass and necromass was insignificant. The effect of snow removal on the production, mortality and disappearance of fine root, and on total C and N concentrations of fine root biomass and necromass were insignificant. The fine root biomass of oak was significantly greater than that of Sasa, although the fine root necromass of Sasa was significantly greater than that of oak. Fine root necromass showed clear seasonal change, although a seasonal change of fine root biomass was unclear. Total C concentration in the fine root biomass and necromass of oak was significantly higher than that of Sasa. Total N concentration in the fine root necromass in May 2015, when after the snow removal, of Sasa was significantly higher than that of oak, in both snow removal and control plots. Our results showed that the fine root necromass of Sasa supplies more N than that of oak in spring, regardless of snowpack depth.

Carbon contents and fine root production in tropical silvopastoral systems

AbstractOwing to the increasing extension of land for livestock production, silvopastoral practices have been among the promising approaches to enhance carbon (C) sequestration. However, the extent of C sequestration in different silvopastoral systems (SPS) and their relationship with fine root production (FRP) is not well understood. The objective of this research was to evaluate the changes in C storage, FRP, and turnover in a part of tropical SPS. We evaluated above‐ and belowground C storage, FRP and turnover in live fences (LF), dispersed tree (DT) silvopasture, and compared these with open pasturelands (OP) in Southeastern Mexico. We applied the stock change approach to calculate biomass growth rates and the ingrowth monolith method for FRP. Biomass stocks in the same plots are re‐measured over time in the stock change approach. Woody biomass stocks differed significantly between SPS (DT: 37.2, LF: 9.8 Mg ha−1) and the accumulation rates in both SPS were significantly higher than zero (0.2–2.2 Mg ha−1 yr−1). Soil organic carbon (SOC) contents were significantly higher in SPS (LF: 2.4%, DT: 3.1%) compared to OP (1.6%). FRP significantly differed between SPS (LF: 27.8, DT: 45.4, and OP: 9.4 g m−2 yr−1) and correlated positively with SOC content. Higher SOC reduced soil compaction in silvopastoral lands as indicated by lower soil bulk density. The results on C stocks change and fine root dynamics contribute to understanding C sequestration potential of tropical SPS, identifying ecologically sound strategies to mitigate greenhouse gases from the livestock sector, and aid restoration of ecosystem services for degraded pasturelands.

Seasonal patterns of fine root dynamics and their contribution to net primary production in hinoki cypress (Chamaecyparis obtusa) and konara oak (Quercus serrata) forests

Key messageFine root and litterfall are major contributor of NPP and fine root production may reflect forest productivity in a warm-temperate forest in Japan.Forest ecosystems play an important role as the major carbon sink on land, with fine root dynamics and litterfall representing major carbon fluxes. The objectives of this research were to estimate NPP including annual fine root production values, to investigate fine root dynamics and the relationships between above– and belowground organs in konara oak (Quercus serrata) and hinoki cypress (Chamaecyparis obtusa) forests. Litterfall was collected seasonally for 1 year from June 2013. The ingrowth core method and the sequential soil core method were applied with a root litterbag experiment to estimate fine root (< 2 mm) production (FRP), mortality (FRM), and decomposition (FRD) for 1 year (from 2013 to 2014), using the continuous inflow estimate method and the simplified decision matrix. The total NPP ranged from 8.2 to 13.9 (t ha− 1 yr− 1), and the sum of aboveground litterfall and FRP accounted for 60% of the total NPP on average, confirming the significance of above- and belowground litter for the forest NPP as a source of detritus for the decomposer system. In hinoki cypress stand, fine root biomass peaked in the end of winter while fine root necromass showed the highest peak in late summer. In konara oak stand, only very fine root (< 0.05 mm) biomass and necromass demonstrated significant seasonal patterns. The seasonal patterns of fine root production did not differ between forest types and root diameter classes. We found a possible relationship between above- and belowground production and fine root production tended to be high in productive forests. This study improves our understanding of different patterns of carbon dynamics between temperate broadleaved and coniferous forest ecosystems.

Biomass Allocation to Resource Acquisition Compartments Is Affected by Tree Density Manipulation in European Beech after Three Decades

This study reports on an investigation of fine root and foliage productivity in forest stands dominated by European beech (Fagus sylvatica L.) and exposed to contrasting intensities of mature forest harvesting. The main aim of this study was to consider the long-term effects of canopy manipulation on resource acquisition biomass compartments in beech. We made use of an experiment established in 1989, when five different light availability treatments were started in plots within a uniform forest stand, ranging from no reduction in tree density to full mature forest removal. We measured fine root standing stock in the 0–30 cm soil layer by coring in 2013 and then followed annual fine root production (in-growth cores) and foliage production (litter baskets) in 2013–2015. We found that the plot where the tree density was reduced by 30% had the lowest foliage and the highest fine root production. In 2013, this plot had the highest fine root turnover rate (0.8 year−1), while this indicator of fine root dynamics was much lower in the other four treatments (around 0.3 year−1). We also found that the annual fine root production represented around two thirds of annual foliage growth on the mass basis in all treatments. While our findings support the maintenance of source and sink balance in woody plants, we also found a long-lasting effect of tree density manipulation on investment into resource acquisition compartments in beech forests.

Root Mass and Elemental Concentrations in an Irish Oak Woodland

Fine roots (&lt; 2 mm diameter) are key for nutrient and carbon cycling in forests but less well studied for oak than other European trees. To better understand controls on root mass and nutrient concentrations in oak stands, a study was conducted at Glendalough in Ireland. Roots were removed from soils and measured for biomass, length and nutrient concentrations along with soil nutrients. Fine root mass was 360 gm-2 and comparable to other oak stands. Whilst root N concentrations were high, P concentrations were low and N, P, K, Mg, but not C or Ca were at greater concentrations in fine roots compared to coarse (2-5 mm) roots. The root Ca:Al ratio suggested Al toxicity although this was less marked in organic-rich soils. Neither root mass nor root nutrient concentrations showed particularly strong correlations with soil nutrients or pH. Whilst this data agrees well with other similar studies, improved analysis by separating live and dead roots will further advance our understanding of controls on forest fine root dynamics.

Fine-root dynamics vary with soil depth and precipitation in a low-nutrient tropical forest in the Central Amazonia.

A common assumption in tropical ecology is that root systems respond rapidly to climatic cues but that most of that response is limited to the uppermost layer of the soil, with relatively limited changes in deeper layers. However, this assumption has not been tested directly, preventing models from accurately predicting the response of tropical forests to environmental change.We measured seasonal dynamics of fine roots in an upper-slope plateau in Central Amazonia mature forest using minirhizotrons to 90cm depth, which were calibrated with fine roots extracted from soil cores.Root productivity and mortality in surface soil layers were positively correlated with precipitation, whereas root standing length was greater during the dry periods at the deeper layers. Contrary to historical assumptions, a large fraction of fine-root standing biomass (46%) and productivity (41%) was found in soil layers deeper than 30cm. Furthermore, root turnover decreased linearly with soil depth.Our findings demonstrate a relationship between fine-root dynamics and precipitation regimes in Central Amazonia. Our results also emphasize the importance of deeper roots for accurate estimates of primary productivity and the interaction between roots and carbon, water, and nutrients.

Patterns and controls on fine-root dynamics along a rainfall gradient in Ghana

Fine-root biomass relates to environmental variables differently along a rainfall gradient in Ghana. Understanding changes in root dynamics in response to environmental factors is crucial for projections of climate change, yet information on controls of root dynamics is limited in the tropics. This study quantified fine-root dynamics along a rainfall gradient in Ghana, ranging from dry to wet evergreen forests. Fine-root biomass and necromass were estimated by the sequential coring method for a year and analyzed in relation to measured environmental factors (rainfall, soil moisture content, air temperature and soil temperature). Overall, fine-root biomass increased along the gradient with the highest estimate found in the wet forest site. Mean annual fine root production ranged from 276.60 to 348.95 gm−2 year−1 across the different forest types. Fine-root turnover rates ranged from 2.3 to 3.1 year−1, and roots tended to turn over faster in the dry than in the moist and wet forest sites. There was a non-linear but significant relationship between fine-root biomass and soil moisture content in the wet forest. None of the environmental factors related to fine-root biomass in the moist forest. However, there was a significant non-linear relationship between rainfall and fine-root biomass in the dry forest site. These results suggest that environmental factors influence fine-root biomass differently across the three forest types. Therefore, future studies should focus on a comprehensive measurement of environmental controls to deepen our understanding of fine root dynamics.

Effect of Pollarding for Fodder on Fine Root Dynamics of Soil Conservation Willow Trees in New Zealand

A field study of the effect of pollarding on fine root development of tree willow (Salix matsudana × alba 'Tangoio') was carried out measuring fine and coarse root length and mass for unpollarded (UP), pollarded (IP) and repollarded trees (RP) at 3-monthly intervals over a period of 1 year following pollarding.

Pioneer root invasion and fibrous root development into disturbed soil space observed with a flatbed scanner method

Fine roots with thick diameter preferentially elongated into disturbed soil space, indicating positive invasion of pioneer roots that recolonize distal root systems. Fine roots and their morphological traits are related to below-ground resource dynamics at physiological and ecological levels. Established approaches for investigating fine root dynamics inevitably cause artificial soil disturbance due to root excavation or instrument installation into the soil. Soil disturbance can have considerable effects on fine root dynamics. The aim of the present study was to clarify the temporal changes of morphological traits of fine roots produced after soil disturbance. The flatbed scanner method was employed in cypress (Chamaecyparis obtusa Endl.) and deciduous oak (Quercus serrata Thunb.) stands, and changes in length and diameter of elongated roots were measured for 4 years after soil disturbance. In both stands, specific trends of diameter and length production of fine roots were observed. Root length production increased extensively, and diameter was greater in an initial phase after soil disturbance. However, temporal patterns varied between the two stands. Soil disturbance affected fine root dynamics for a longer duration in the cypress stand, but more intensively in the oak stand. These results indicate that soil disturbance can affect fine root morphology and can induce invasion of thick fine roots, which are traditionally grouped as pioneer roots. Moreover, the results showed high length production continued for a longer period than that of larger diameter roots, suggesting recolonization of fine root systems by elongating pioneer roots followed by the branching of absorptive fibrous roots in order to recover root uptake capacity lost due to soil disturbance.

四种不同生活型树种细根寿命及影响因素

PDF HTML阅读 XML下载 导出引用 引用提醒 四种不同生活型树种细根寿命及影响因素 DOI: 10.5846/stxb201904020641 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（30800137，31270489） Fine root lifespan and influencing factors of four tree species with different life forms 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:以4种不同生活型树种（常绿阔叶和针叶树种、落叶阔叶和针叶树种）为研究对象，通过微根管法现地观测细根的生长动态，比较不同生活型树种细根寿命在种内和种间的差异，探讨影响细根寿命的主要因子，研究结果对理解和预测森林生态系统碳及养分循环过程具有重要的理论意义。结果表明：（1）细根形态特征（分枝结构和直径）显著影响种内细根寿命，分枝等级越低、直径越小，细根的寿命越短；（2）4个树种的细根寿命表现出明显的土层效应和季节效应，即随土壤深度增加，细根的累积存活率逐渐增加，寿命延长；而不同季节出生的细根其寿命长短模式在树种间不一致，春季或夏季出生的细根寿命要长于秋冬季；（3）常绿树种（柳杉、石栎）的细根寿命要长于落叶树种（池杉、麻栎），同时，针叶树种（池杉、柳杉）的细根寿命要长于阔叶树种（麻栎、石栎）。在同一树种内，细根寿命受细根直径、根系分枝结构、土壤环境因子（土层）等因素显著影响，但在不同树种间，细根寿命可能更依赖于树木生长速率、碳分配模式等树木整体的功能性状差异。 Abstract:In this study, four tree species with different life forms (evergreen broad-leaved, coniferous species, deciduous broad-leaved, and coniferous species) were used as the experimental materials. The growth dynamics of fine roots were observed by minirhizotron method. We compared differences in the root lifespan for tree species with different life forms within and between species, and also explored the main factors affecting the lifespan of fine roots. The study would help us to understand carbon and nutrient cycling processes in forest ecosystems. The results showed that: (1) fine root morphological characteristics (branched structure and root diameter) significantly affected the lifespan of fine roots within the species. The fine root lifespan with the lower branching order and the smaller diameter was shorter than that of the higher-order roots and the coarser roots. (2) The root lifespan showed obvious soil layer effect and the seasonal effect, that is, with the increase of soil depth, the cumulative survival rate of fine roots gradually increased and the root lifespan was prolonged; while the lifespan pattern of fine roots born in different seasons was inconsistent among tree species. The lifespan of the fine roots born in spring or summer was longer than that born in autumn and winter. (3) The fine roots lifespan of evergreen trees (Lithocarpus glaber and Cryptomeria fortunei) was longer than that of deciduous trees (Quercus acutissima and Taxodium ascendens). The fine root lifespan of conifers trees was longer than that of broadleaf species. Generally, within the tree species, the fine root lifespan is significantly affected by factors such as fine root diameter, root branching structure, and soil environmental factors (soil layer). However, between tree species, fine root lifespan may be more dependent on the differences in functional traits of trees as a whole, such as tree growth rate, carbohydrate distribution patterns. 参考文献 相似文献 引证文献

Effects of Microtopography on Absorptive and Transport Fine Root Biomass, Necromass, Production, Mortality and Decomposition in a Coastal Freshwater Forested Wetland, Southeastern USA

Forested wetlands are an important carbon (C) sink. Fine roots (diameter < 2 mm) dominate belowground C cycling and can be functionally defined into absorptive roots (order 1–2) and transport roots (order ≥ 3). However, effects of microtopography on the function-based fine root dynamics in forested wetlands are poorly understood. We studied fine root biomass allocation and biomass, necromass, mass loss rate, production, mortality and decomposition of absorptive and transport roots in hummocks and hollows in a coastal plain freshwater forested wetland (FFW) in the southeastern USA using dynamic-flow method. Biomass ratios of first- to second-order roots and absorptive to transport roots and the biomass and necromass of absorptive and transport roots were significantly higher in top 0–10 cm organic peat layer than in 10–20 cm muck and mineral layer, and were significantly higher in hummocks than in hollows. The mass loss rate, production, mortality and decomposition were significantly higher in hummocks than in hollows. Absorptive roots did not have a lower mass loss rate than transport roots. Microtopography significantly affected the contributions of absorptive and transport roots to the total production, mortality and decomposition. Production, mortality and decomposition of absorptive roots were higher than those of transport roots in hummocks but lower than those of transport roots in hollows. Total (hummocks plus hollows) fine root production, mortality and decomposition were 455 ± 106 g m−2 y−1, 475 ± 79 g m−2 y−1 and 392 ± 60 g m−2 y−1, respectively. Greater mortality than decomposition resulted in net fine root C input to soil. The observed microtopographic controls on fine root dynamics have great implications for soil C cycling. As sea level rises, the relative area of hollows in coastal plain FFWs will increase, causing a decrease in fine root mass loss rate, biomass, production, mortality and decomposition and it is the balance of these processes that will determine future soil C storage and cycling.

Fine root dynamics and partitioning of root respiration into growth and maintenance components in cool temperate deciduous and evergreen forests

We aim to show the seasonality of fine root dynamics and examine the relationship between root respiration (Rr) and fine root dynamics. In addition, we try partitioning Rr into growth (Rg) and maintenance (Rm) components. Soil respiration (Rs), fine root biomass (B), and fine root production (P) were measured simultaneously over a growing season in adjoining deciduous (DF) and evergreen (EF) forests. The Rr was separated from Rs by the trenching method, and Rr was partitioned into Rg and Rm using an empirical model. The seasonality of P was almost the same in both forests, though that of B was different. The Rr showed a positive correlation with P in both sites. Annual Rr was estimated to be 610 (DF) and 393 (EF) g C m−2 year−1. Annual Rg and Rm were 121 and 166 (DF), and 86 and 182 (EF) g C m−2 year−1, respectively. We found a clear seasonal pattern in P and a positive linearity between Rr and P. Despite considerable uncertainty due to the small sample size, presence of larger roots, and measurement uncertainty, the results suggest that our approach is capable of partitioning Rr.

Variations in fine root dynamics and turnover rates in five forest types in northeastern China

Quantifying fine root (≤ 2.0 mm in diameter) distribution and turnover is essential for accurately estimating forest carbon budgets. However, fine root dynamics are poorly understood, possibly because of their inaccessibility. This study quantifies fine root distribution and turnover rates for five representative Chinese temperate forests types. Fine root number, diameter, biomass, necromass, production, mortality, and turnover rates were measured using a minirhizotron over a 12-month period. More than 90% of the fine roots were < 0.5 mm in diameter, with thin fine roots at shallow layers, and thicker ones in deeper soil layers. The fine root dynamics were significantly different among the forest types. Coniferous plantations had fewer fine roots, less biomass, necromass, production and mortality but greater average diameters than fine roots of broadleaved forests. All traits, except for diameter, decreased along the soil profile. Fine root numbers and production exhibited a unimodal seasonal pattern with peaks occurring in summer, whereas biomass, necromass and mortality progressively increased over the growing season. The turnover rates of roots < 0.5 mm varied from 0.4 to 1.0 a−1 for the five forest types, 0.5–1.0 a−1 for the soil layers and 0.2–1.1 a−1 for the seasons, with the largest turnover rate at the 0–10 cm depth in summer. The patterns of fine root numbers, biomass, necromass, production, mortality, and turnover rates varied with forest types, soil depths, growing season and diameter classes. This study highlights the importance of forest types and diameters in quantifying fine root turnover rates.