Fine Root Characteristics Research Articles

Introducing Native Tree Species Alter the Soil Organic Carbon, Nitrogen, Phosphorus, and Fine Roots in Moso Bamboo Plantations

Bamboo and wood-mixed forests are management models that remarkably enhance the balance and productivity of bamboo ecosystems. However, the effects of this model on soil nutrients and enzyme activities remain largely unknown. This study compared the soil organic carbon, nitrogen, phosphorus, and enzyme activity, along with the characteristics of fine roots in pure Moso bamboo plantations (CK) and those mixed with Liriodendron chinense (ML), Sassafras tzumu (MS), Cunninghamia lanceolata (MC), and Pseudolarix amabilis (MP). The results showed that mixed forests improve carbon pools in 0–40 cm soil layers, increasing the total organic C(TOC), free particulate organic C (fPOC), occluded particulate organic C (oPOC), hot-water-extractable organic C (DOC), and mineral-associated organic C (MOC). They also increase soil total N, total P, available N, available P, NH4+-N, NO3−-N, inorganic P, organic P, and microbial biomass N. Bacterial and fungal abundances, along with enzyme activities (urease, acid phosphatase, polyphenol oxidase, peroxidase, and β-glucosidase), also improved. MP and MS were the most effective. Moreover, MS and MP supported a higher biomass and length of fine root and increased the nitrogen and phosphorus uptake of Moso bamboo. In conclusion, Sassafras tzumu and Pseudolarix amabilis are optimal for mixed planting, offering substantial benefits to soil nutrient dynamics and preventing soil quality decline in Moso bamboo forests, thereby supporting better nutrient cycling and carbon sequestration. This research offers insights into enhancing soil quality through diversified Moso bamboo forestry.

Evaluation of Fine Root Morphology and Rhizosphere Environmental Characteristics of the Dioecious Idesia polycarpa Maxim

To explore the differences in the fine root characteristics and rhizosphere environment of male and female Idesia polycarpa Maxim at different stages, 7-year-old male and female I. polycarpa were used as plant materials. The fine root characteristics were measured with a root scanner, and rhizosphere soil was collected at the flowering stage (May), fruit accumulation stage (July), and fruit maturity stage (October). In addition, this study analyzed the soil nutrient characteristics of these conditions at different stages. At the same time, Illumine high-throughput sequencing technology and gas chromatography–tandem mass spectrometry (GC–MS) technology were used to analyze the rhizosphere microbes and metabolites of male and female plants at different stages. The results showed that the total root length, surface area, total volume, root tip number, and total average diameter of the fine root of female plants were larger than those of male plants, and the difference reached its maximum in the fruit material accumulation stage. Total carbon (TC) and total nitrogen (TN) content in the rhizosphere soil of male and female plants significantly differed over multiple stages, while available soil nitrogen and potassium content significantly differed during fruit ripening. The rhizosphere microbial composition of male and female plants was similar, and the dominant bacteria in the rhizosphere soil of each stage were Proteobacteria, Acidobacteria, Ascomycota, and Mortierellomycota. The relative abundance of Bacillus, Arthrobacter, Volutella, and Neocosmospora in rhizosphere soil at different stages differed between male and female plants. Combined with the OPLS-DA model and database retrieval, 29 significantly different metabolites, most of which were carbohydrates, were detected in the rhizosphere soil of male and female plants. Moreover, there were more significant metabolites in the rhizosphere soil at the flowering stage than in the fruit ripening stage. Through RDA analysis, available potassium (AK), Pedomicrobium, Chaetomium, and Glucose 1 had the greatest influence on fine root traits of I. polycarpa. The results indicated that the fine root traits were negatively correlated with AK and rhizosphere metabolites. Moreover, positive correlations were found with rhizosphere microorganism traits. The above results laid a foundation for the field management of I. polycarpa and the screening and application of rhizosphere growth-promoting bacteria resources.

Persistent soil organic carbon deficits from converting primary forests to plantations and secondary forests in subtropical China

Soil organic carbon (SOC) plays a critical role in supporting key ecosystem functions and services for humanity. Despite the widespread conversion of primary forests to plantations and secondary forests, it remains uncertain how it affects the content and distribution of SOC. We evaluated SOC content, its components in two fractions, particulate organic carbon (a mean residence time shorter than decades) and mineral-associated organic carbon (a mean residence time of multiple decades to centuries), and the fine root characteristics (biomass, necromass, and C: N of dead fine roots) across Chinese fir plantations and secondary forests during stand development (5–41 years old) in subtropical China, employing primary forests as a reference. We found that SOC content differed significantly between forest types and soil depths, but not with stand age within plantations or secondary forests. In the topsoil (0–10 cm), the SOC content of primary and secondary forests was 47 % and 25 % higher than that of Chinese fir plantations, respectively. The SOC content in the subsoil (40–60 cm) was approximately 6 ± 1.7 mg C g−1 and did not change significantly with forest types or stand ages. The higher SOC contents in primary forests and secondary forests in topsoil resulted primarily from particulate organic carbon accumulation caused by higher fine root biomass and dead root C: N. The fraction of mineral-associated organic carbon to SOC increased with soil depth and was higher in Chinese fir plantations than in secondary forests, suggesting that more SOC is composed of mineral-associated organic carbon that was associated with a higher amount of fine root necromass. Contrary to our expectations, we found SOC content or its fractions did not increase with 40 years of plantation and secondary forest development. Our results reveal persistent SOC deficits from converting primary forests to plantations and secondary forests and highlight the urgent need to conserve the remaining primary forests and protect secondary forests and plantations from disturbances, allowing them to evolve towards older-aged primary forests.

Dynamics of Fine Root Decomposition in Different Vegetation Types: Investigating the Impact of Soil Fungal Communities and Enzyme Activities

Fine root decomposition plays a vital role in driving the carbon cycle in terrestrial ecosystems, as it constitutes a substantial part of annual net primary production and, as transient tissues, returns to the soil within relatively short timescales. Soil fungal communities and enzyme activities strongly influence this process. In this study, we used an in situ soil core decomposition method to compare the fine root decomposition rates of Liriodendron chinense (Hemsl.) Sargent, Cunninghamia lanceolata (Lamb.) Hook, and Phyllostachys edulis (Carrière) J.Houz forests over a 1-year period (March 2021–March 2022). We quantified the chemical attributes of fine roots and soil enzymatic activities across different forests, detected fungal communities via ITS rRNA gene sequencing, and forecasted fungal functional groups using the FUNGuild database. The results showed that fine root decomposition was fastest in the Liriodendron chinense (Hemsl.) Sargent forest (77.2%) and the slowest for Cunninghamia lanceolata (Lamb.) Hook (59.2%). Structural equation modeling (SEM) results indicated that the carbon content of fine roots and the functional groups of soil fungi are crucial to fine root decomposition. They not only directly influence fine root decomposition but also promote it through soil enzymatic activities, clearly suggesting that changes in soil enzymatic activities can be employed to explain the ecological effects of the root decomposition process. This study illuminates significant differences in the chemical characteristics of fine roots, soil enzymatic activities, and soil fungal communities among different forest types, all of which significantly affect fine root decomposition.

Response of Fine-Root Traits of Populus tomentosa to Drought in Shallow and Deep Soil

Understanding the response characteristics of fine roots to soil drought of different degrees is essential for revealing the ecological adaptability of trees to different water environments and diverse plant resource absorption strategies. This study focused on a Chinese white poplar (Populus tomentosa) plantation stand, which gradually experienced the process of deep soil drying. In 2019 and 2021, by measuring the fine-root length density (FRLD), mean root diameter (MRD), specific root length (SRL), and root tissue density (RTD) of 1920 root samples and continuously monitoring the soil water content (SWC) in 0–600 cm soil layers, we explored the response characteristics of fine-root distributions and morphological traits relative to soil drought of different degrees. The results showed that P. tomentosa primarily changed the fine-root vertical distribution rather than the total amount of fine roots for coping with soil drought of different degrees. Shallow soil drought induced more fine-root distributions in the deep soil layer, while drought in both shallow and deep soil further aggravated this trend. Shallow soil drought restrained shallow fine-root growth, yet deep soil drought promoted deep fine-root growth. The very deep fine roots (400–600 cm) were more sensitive to soil drought than shallow fine roots. The shallow soil drought significantly increased the SRL of very deep fine roots; in contrast, when deep soil drought also occurred, the MRD and SRL significantly increased and decreased, respectively. In addition, fine-root morphological traits exhibited significant vertical spatial and temporal variation. MRD increased and then decreased, and the RTD gradually decreased with depth, while SRL had an increased trend in the very deep soil layer (400–600 cm). When the rainy season came, MRD and SRL increased and decreased, respectively. In conclusion, when facing gradual deep soil drying, P. tomentosa will use a large range of rooting patterns to meet the water demand of the canopy. These patterns range from “drought tolerant strategies” by distributing more fine roots in the deeper soil layer where water is abundant to “drought tolerant strategies” by changing very deep fine-root morphological traits to improve water-absorbing and transporting efficiencies. Our findings provide insight into the ecological adaption strategy of tree root systems relative to soil drought of different degrees in arid and semi-arid regions and provide crucial theoretical support for developing water management technologies to cope with deep soil drying under climate change.

增温和氮添加对杉木不同序级细根形态和化学性状的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 增温和氮添加对杉木不同序级细根形态和化学性状的影响 DOI: 10.5846/stxb202204291200 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金重点项目（31830014）；国家重点研发计划项目课题项目（2021YFD2200403） Effects of soil warming and nitrogen addition on the morphological and chemical characteristics of fine roots in different order classes of the Chinese fir Author: Affiliation: Fund Project: National Natural Science Foundation of China(31830014);Topics of state key R & D projects（2021YFD2200403） 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:全球气候变暖与氮（N）沉降是两个同时存在的全球变化主要因素，但目前关于二者的研究多以单因子为主。细根形态和化学性状等功能性状在促进植物养分获取和森林生物地球化学循环方面起着关键作用，但目前气候变暖、N沉降以及两者交互对细根形态和化学性状的影响尚不清楚。在福建三明森林生态系统国家野外科学观测研究站陈大观测点开展土壤增温与N添加双因子试验，包括对照（无增温，无氮添加）、低氮（+4gN m-2 a-1）、高氮（+8gN m-2 a-1）、增温（+5℃）、增温+低氮（+5℃，+4gN m-2 a-1）、增温+高氮（+5℃，+8gN m-2 a-1）六个处理，探讨增温与N添加对杉木（Cunninghamia Lanceolata）细根形态和化学性状的影响。结果表明：（1）增温显著增加了细根直径（D）。增温和N添加的交互作用对细根比根长（SRL）、比表面积（SRA）及组织密度（RTD）均存在显著影响，与对照相比，增温处理及增温+高氮处理均降低了细根SRL和SRA；不同处理间细根RTD无显著差异。N添加与序级交互作用对细根SRA存在显著影响，仅低氮添加显著增加了1级根SRA。（2）增温和N添加交互作用对细根碳（C）含量存在显著影响，与对照相比，仅增温+高氮处理显著增加了细根C含量。N添加与序级交互作用对细根C含量存在显著影响，仅在1级细根中，高氮添加的细根C含量要显著高于低氮添加。增温、N添加以及序级三者交互作用对细根N含量及碳氮比（C ： N）存在显著影响，与对照相比，低氮和高氮处理对细根N含量及C ： N影响因序级而异；增温处理、增温+低氮处理以及增温+高氮处理均显著提高了细根N含量，降低了细根C ： N；与高阶根相比，低阶根N含量和C ： N对单独增温处理及增温+低氮处理响应要更为敏感。以上结果表明，不同细根功能性状对增温、N添加及两者交互的响应存在差异，这种差异主要与细根序级和N添加水平有关；增温和N添加抑制了细根SRL和SRA，但促进了细根N含量并降低了细根C ： N，这将有助于理解亚热带地区森林地下养分循环以及C固存对全球环境变化的响应。 Abstract:Global warming and nitrogen deposition are two main global change drivers, often occurring simultaneously. However, most of related studies referred to only single factor. Fine root functional traits such as morphology and chemical properties play a key role in promoting plant nutrient acquisition and forest biogeochemistry cycling. The effects of climate warming, N deposition and their interactions on fine root morphology and chemical properties remain unclear. To explore the effects of warming and N addition on the morphological and chemical characteristics of fine roots of Cunninghamia Lanceolata. We conducted a two-factor experiment of soil warming and nitrogen addition, which consisted control (CT), low nitrogen treatment (LN), high nitrogen treatment (HN), warming treatment (W), warming and low nitrogen treatment (WLN), warming and high nitrogen treatment (WHN), at the Forest Ecosystem and Global Change Research Station of Fujian Normal University, Chenda, Sanming, Fujian Province. The results showed that:(1) the warming significantly increased fine root diameter (D). The interaction of warming and N addition had significant effects on the specific root length (SRL), specific surface area (SRA) and root tissue density (RTD) of fine roots. Compared with CT, the W and WHN reduced fine root SRL and SRA; there was no significant difference in RTD of fine roots among different treatments. The interaction of N addition and order had significant effects on fine root SRA. Low nitrogen addition only increased SRA of first order root significantly. (2) The interaction of warming and N addition had a significant effect on fine root C concentration, and only WHN significantly increased fine root C concentration. The interaction of N addition and order had significant effects on fine root concentration. The fine root C concentration of high N addition was significantly higher than that of low N addition. The interaction of warming, N addition and order had significant effects on fine root N concentration and C:N. Compared with CT, the effects of LN and HN on fine root N content and C:N varied with the order; The W, WLN and WHN significantly increased the fine root N concentration and decreased the fine root C:N. Compared with high-order root, low-order root N concentration and C:N were more sensitive to the effects of W and WLN. The results showed that the responses of fine root morphology and chemical characteristics to warming, N addition and their interaction were different, and the differences were mainly regulated by fine root branch order and N addition level; The warming and N addition promoted fine root N concentration and decreased fine root C:N, which would contribute to understand the subsurface nutrient cycling and the response of C sequestration to global environmental change in subtropical forests. 参考文献 相似文献 引证文献

Effects of warming on growth, morphology and physiological metabolism characteristics of fine roots in a mature <i>Cunninghamia lanceolata</i> plantation in different seasons

Effects of warming on growth, morphology and physiological metabolism characteristics of fine roots in a mature <i>Cunninghamia lanceolata</i> plantation in different seasons

In Situ Rainwater Collection and Infiltration System Alleviates the Negative Effects of Drought on Plant-Available Water, Fine Root Distribution and Plant Hydraulic Conductivity

Soil water status and fine-root characteristics are the foundation for implementing forest water-management strategies in semiarid forest plantations, where rainwater is always the sole source of water for plant growth. Rainwater management and utilization are effective strategies to alleviate water scarcity in semiarid areas as ground water is always inaccessible there. Through the implementation of an in situ rainwater collection and infiltration system (IRCIS), we investigated the effects of IRCIS on soil water and fine-root distributions in the 0–5 m soil profile in a wet (2015, 815 mm) and a dry year (2016, 468 mm) in rainfed Robinia pseudoacacia forests in the Loess Plateau region of China. The results showed drought significantly decreased plant water availability and hydraulic conductivity of roots and branches, but strongly increased soil moisture deficits and fine-root (<2 mm diameter) biomass. With the implementation of IRCIS, soil profile available water and plant hydraulic conductivity can be significantly increased, but soil moisture deficits and fine-root (<2 mm diameter) biomass can be significantly decreased. Drought also significantly influenced the root distribution of Robinia pseudoacacia. The maximum depth of Robinia pseudoacacia roots in the dry year was significantly greater than in the wet year. Therefore, Robinia pseudoacacia can absorb shallow (0–1.5 m) soil water in wet years, while utilizing deep (>1.5 m) soil water in dry years to maintain normal growth and resist drought stress. The results of this study will contribute to the formulation of appropriate strategies for planning and managing rainwater resources in forest plantations.

Effects of Tree Species on Moso Bamboo (Phyllostachys edulis (Carriere) J. Houzeau) Fine Root Morphology, Biomass, and Soil Properties in Bamboo–Broadleaf Mixed Forests

Understanding fine root characteristics in relation to soil properties of bamboo–broadleaf mixed forests may help optimize belowground production management and ecological functions in mixed-forest ecosystems. In this study, we compared four different bamboo–broadleaf mixed forests: Castanopsis chinensis (Sprengel) Hance with moso bamboo (CCB), Alniphyllum fortunei (Hemsl.) Makino with moso bamboo (AFB), Choerospondias axillaris (Roxb.) Burtt and Hill with moso bamboo (CAB), and Castanopsis fargesii Franch with moso bamboo (CFB), and analyzed their effects on the traits of fine roots of moso bamboo, soil nutrient contents, and enzyme activities. In January 2022, fine root and soil samples from four different mixed bamboo–broadleaf forests were collected from a subtropical region of Fujian Province, China. Results showed that CAB significantly increased fine root biomass (FRB) and root length density (RLD); however, specific root length (SRL) was only in the 0–20 cm soil layer. Specific surface area (SSA) was significantly reduced in the CCB in the 0–20 cm and 20–40 cm soil layers. The total phosphorous (TP) and total potassium (TK) contents of AFB and CAB were significantly increased (p < 0.05), and the alkali-hydrolyzable nitrogen (AN) content was significantly increased by CCB in the 0–20 cm soil layer (p < 0.05). Additionally, CFB increased the activities of acid phosphatase (ACP) and catalase (CAT) but decreased the activity of sucrase (SC). Principal component analysis showed that fine root traits (FRB, RLD, SRL, and SSA) were not only positively associated with soil organic carbon (SOC), total nitrogen (TN) and available potassium (AK) but also associated with urease (UE) and CAT. Therefore, belowground interactions between different species have a significant impact on the characteristics of fine roots and soil in bamboo–broadleaf mixed forests.

Effects of Tree Species Diversity on Fine Root Morphological Characteristics, Productivity and Turnover Rates

Fine roots (φ ≤ 2 mm) play an important role in the process of material and nutrient cycling in forest ecosystems, but the effect of tree species diversity on the functional characteristics of fine roots is unclear. In this study, 1−7 subtropical communities with different species richness were selected to study the morphological characteristics, productivity (PRO), and turnover rate (TUR) of fine roots by continuous soil core extraction, ingrowth soil core method, and root analysis system. The effects of tree species diversity on fine root morphological characteristics, PRO, and TUR are also analyzed. The results showed that with the increase in tree species diversity in the community, the effect of fine root morphological characteristics including specific root length (SRL) and specific surface area (SSA) of each community was not significant, but the fine root PRO in the community increased from 71.63 g·m−2·a−1 (Ligustrum lucidum pure forest) to 232.95 g·m−2·a−1 (Cinnamomum camphora mixed forest with seven species richness communities), and the fine root TUR increased from 0.539 times·a−1 to 0.747 times·a−1. Correlation analysis and redundancy analysis showed that species richness, root functional traits, and soil physicochemical properties were important driving factors affecting root characteristics. The increase in tree species diversity did not change the morphological characteristics of fine roots but increased the PRO and TUR of fine roots.

Anatomical structure interpretation of the effect of soil environment on fine root function.

Fine root anatomy plays an important role in understanding the relationship between fine root function and soil environment. However, in different soil environments, the variation of fine root anatomical structure in different root sequences is not well studied. We measured the soil conditions and anatomical structure characteristics (root diameter, cortical tissue, vascular tissue and xylem) of fine roots of Cupressus funebris in four experimental sites, and analyzed each level of fine roots separately. We link these data to understand the relationship between fine root anatomy and soil conditions. We found that the anatomical structure of fine roots is closely related to soil environmental factors. The fine roots of lower root order are mainly affected by soil nutrients. Among them, the cortical tissue of first-order fine roots was positively correlated with potassium and phosphorus, but negatively correlated with nitrogen, while second- and third-order fine roots was positively correlated with soil total potassium and negatively correlated with nitrogen and phosphorus. For the fine roots of high root order, the cortical tissue disappeared, and the secondary vascular tissue was mainly affected by soil moisture. In addition, we also found that the division of fine root functional groups is not fixed. On the one hand, the function of third-order fine roots will slip. For example, the decrease of soil moisture will promote the transformation of third-order fine roots into transport roots, and the reduction of nitrogen will promote the transformation of third-order fine roots into absorption roots to fix nitrogen. This transformation strategy can effectively prevent the restriction of soil nutrients on plant growth. On the other hand, with the change of habitat, the first- and second-order fine roots are still the absorbing root, and the fourth- and fifth-order fine roots are still the transport root, but the efficiency of absorption and transport will be affected. In conclusion, our findings emphasize the fine roots in different soil environment to show high levels of plasticity, shows that fine root anatomical structure changes may make plants, and reveals that the fine is just order of reaction and its mechanism in the soil environment.

Responses of Fine Roots at Different Soil Depths to Different Thinning Intensities in a Secondary Forest in the Qinling Mountains, China.

Simple SummaryFine roots of different sizes make critical contributions to carbon stocks and terrestrial productivity, but the changed characteristics of fine roots with different diameters at different soil depths under thinning disturbances remain poorly understood. In our study, we aimed to elucidate the response characteristics of fine roots with different diameters to thinning intensities at different soil depths, and to explore the driving mechanism of the change in the fine-root characteristics. We found that higher thinning intensities negatively affected 0.5–1 mm and 1–2 mm fine-root biomass, while the <0.5 mm fine-root characteristics fluctuated with increasing thinning intensities. Our results suggest that the thinning intensity exhibits varied influential mechanisms on the changed characteristics of <0.5 mm fine roots and thicker fine roots (0.5–2 mm). Collectively, our findings provide important insights into the effects of forest management on changes in fine-root characteristics, and supplement meaningful data on fine-root productivity to improve the parameterization of future ecological models.Fine roots make critical contributions to carbon stocks and terrestrial productivity, and fine roots with different diameters exhibit functional heterogeneity. However, the changed characteristics of fine roots with different diameters at different soil depths following thinning disturbances are poorly understood. We investigated the biomass, production, mortality and turnover rate of <0.5 mm, 0.5–1 mm, and 1–2 mm fine roots at 0–20 cm, 20–40 cm, and 40–60 cm soil depths under five thinning intensities (0%, 15%, 30%, 45%, and 60%) in a secondary forest in the Qinling Mountains. The biomass, production and turnover rate of <0.5 mm fine roots fluctuated with increasing thinning intensities, while the 0.5–1 mm and 1–2 mm fine-root biomass significantly decreased. The thinning intensities had no effects on the fine-root necromass or mortality. The change in the fine-root characteristics in deeper soils was more sensitive to the thinning intensities. The principal component analysis results showed that increased <0.5 mm fine-root biomass and production resulted from increased shrub and herb diversity and biomass and decreased soil nutrient availability, stand volume, and litter biomass, whereas the 0.5–1 mm and 1–2 mm fine-root biomass showed the opposite trends and changes. Our results suggest that different thinning intensities exhibit varied influential mechanisms on the changed characteristics of fine roots with different diameters.

Shade affects fine-root morphology in range-encroaching eastern redcedars (Juniperus virginiana) more than competition, soil fertility and pH

Fine-root morphological variables are often directly correlated with soil nutrient availability and water absorption. Indirectly, these morphological variables could be related to nutrient depletion by other plants. The relationships of fine-root variables with shade, direct or indirect, are unknown. I tested the relationships between a number of soil quality variables (levels of nitrogen and lime), competition with a co-dominant tree, and shade for the range-encroaching eastern redcedar Juniperus virginiana. I measured seven fine-root parameters as indices of potential nutrient-uptake or competitive ability. I also assessed the relationships of these fine-root parameters with foraging return (i.e., tissue nitrogen, non-structural carbohydrates, relative growth rate and biomass). There were no significant (main) effects of soil amendments (added nitrogen and lime) or tree competition on any of the seven root parameters. There was a significant (indirect) effect of shade (affecting five out of seven fine-root morphological variables), and a significant interaction effect between fertilizer and lime amendments, although the last-mentioned interaction affected one fine-root variable only. There were two additional pieces of evidence that support the effect of shade: a significant difference between shaded and unshaded plants in the slope of the negative relationship between root diameter and specific root length, and a significant overall difference among all fine-root morphological variables in a principal components analysis between shaded and unshaded plants. I found that fractal dimension was the only variable for which there were positive correlations with foraging return, probably because a higher fractal dimension leads to more effective use of nutrients. I expected a negative correlation between foraging returns and fine-root characteristics that incurred substantial costs. I only found a significant cost for specific root length, which may be mediated by the unmeasured parameter of root lifespan.

Variation in Fine Root Characteristics and Nutrient Dynamics Across Alaskan Ecosystems

Carbon cycle perturbations in high-latitude ecosystems associated with rapid warming can have implications for the global climate. Belowground biomass is an important component of the carbon cycle in these ecosystems, with, on average, significantly more vegetation biomass belowground than aboveground. Large quantities of dead root biomass are also in these ecosystems owing to slow decomposition rates. Current understanding of how live and dead root biomass carbon pools vary across high-latitude ecosystems and the environmental conditions associated with this variation is limited due to the labor- and time-intensive nature of data collection. To that end, we examined patterns and factors (abiotic and biotic) associated with the variation in live and dead fine root biomass (FRB) and FRB carbon (C), nitrogen (N) and phosphorus concentrations for 23 sites across a latitudinal gradient in Alaska, spanning both boreal forest and tundra biomes. We found no difference in the live or dead FRB variables between these biomes, despite large differences in predominant vegetation types, except for significantly higher live FRB C:N ratios in boreal sites. Soil C:N ratio, moisture, and temperature, along with moss cover, explained a substantial portion of the dead:live FRB ratio variability across sites. We find all these factors have negative relationships with dead FRB, while having positive or no relationship with live FRB. This work demonstrates that FRB does not necessarily correlate with aboveground vegetation characteristics, and it highlights the need for finer-scale measurements of abiotic and biotic factors to understand FRB landscape variability now and into the future.

Root architecture and fine root characteristics of Juglans mandshurica saplings in different habitats in the secondary forest on the west slope of Zhangguangcailing, China

The whole root excavation method was used to examine root configuration of Juglans mandshurica, with the age of 5-6 years in three habitats (forest edge, gap, and canopy) in a secondary forest on the western part of Zhangguangcailing Mountains. Root structure and fine root function were measured. The root topological index, average joint length, cross-sectional area ratio before and after root branching were calculated and fine root chemical compositions were analyzed. Roots of J. mandshurica at forest edge tended to be dichotomous branch (Topological index:TI=0.68), that under the canopy were herringbone-like branch (TI=0.79), and the gap was between the two (TI=0.72). The average connection length of roots among the three habitats was not significant. The cross-sectional area ratio of roots before and after root branching in three habitats was 1.06, 1.04 and 1.07, respectively, which was not affected by root diameter, in accordance with the Leonardo da Vinci rule. For the same order fine root in different habitats, its length and specific surface area gradually increased from the edge of the forest to the canopy. The N content decreased first and then increased, while the C content and C/N increased first and then decreased. From the forest edge to the gap and to the under canopy, roots tended to move from the dichotomous branch to the herringbone-like branch by reducing the overlap between the secondary branches and roots, increasing specific root length, specific surface area and changing the contents of C and N to cope with environmental change and improve nutrient absorption efficiency.

Stoichiometric characteristics of fine roots and rhizosphere soil of &lt;i&gt;Broussonetia papyrifera&lt;/i&gt; adapted to the karst rocky desertification environment in southwest China

Stoichiometric characteristics of fine roots and rhizosphere soil of &lt;i&gt;Broussonetia papyrifera&lt;/i&gt; adapted to the karst rocky desertification environment in southwest China

The response of fine root morphological and physiological traits to added nitrogen in Schrenk's spruce (Picea schrenkiana) of the Tianshan mountains, China.

Fine roots are essential for water and nutrient uptake in plants, but little is known about the variation in fine root traits and the underlying mechanisms that drive it. Understanding the responses of fine root function traits to changing environmental conditions and the role of fine root traits as drivers of forest ecosystem processes are critical for informing physiological and ecological theory as well as ecosystem management. We measured morphological and physiological traits of fine roots from six soil layers and three diameter classes in Schrenk’s spruce (Picea shrenkiana) forests of the Tianshan mountains, China. We found significant effects of nitrogen addition on these morphological and physiological traits, which varied by soil layer and root diameter. Specifically, specific root length (SRL) was higher in medium N addition group (N2) than in control group (N0). Specific root area (SRA) was higher in the control group (N0) than fertilized groups (N1, N2 and N3). Root tissue density (RTD) was higher in low N addition group (N1) than in the other group. Root dry matter content had no significant difference among four treatment groups. SRL, SRA, and RTD of fine roots in different diameter classes were all significantly different between high N addition (N3) and the control (N0) groups. The physiological characteristics of fine roots showed that soluble sugar (SS), fine root vitality (FRV), and tissue water content (TWC) in different soil layers were higher in the control group than in the fertilized groups. While soluble protein (SP), malondialdehyde (MDA) and free proline (FP) were lower in the control group (N0) than in the fertilized groups. In addition, SS, FRV, SP, TWC, FP, and MDA in all N addition treatments groups were significantly different from the control group. Fine root morphological traits were closely related to physiological traits, and added nitrogen inputs change these correlations. Our study confirms that nitrogen addition has specific effects on the morphological and physiological traits of fine roots of Schrenk’s spruce, and the effects of N addition vary according to the amount added.

Changes in quantity, morphology and nitrogen content of fine roots with stand development in a subalpine fir-wave forest

ABSTRACTTo determine the change in nutrient absorption capacity with stand development, we aimed to clarify the changes in fine root characteristics with stand development and stand characteristics. Stand characteristics (stand age, maximum tree height, tree density and basal area) and fine root characteristics were examined in three fir-wave stands that aged sequentially along the slope in a subalpine Abies forest in central Japan. The biomass, length, surface area and N content of fine roots did not change, but the specific root length (SRL) decreased with stand development, i.e. distance from the upper side of each transect. On the other hand, we observed an increase in fine root biomass with stand characteristics, i.e. maximum tree height and basal area of the Abies community, while a decrease in SRL was also observed. These changes resulted in an increase in surface area and N content of fine roots. However, the surface area of absorptive roots that were <0.5 mm in diameter did not change with stand characteristics. Thus, we suggest that the nutrient absorption capacity of the subalpine Abies community increased with aboveground biomass from the viewpoint of comprehensive activity of fine roots, but not from the viewpoint of fine root morphology. We further confirmed that the ratios of surface area and N content of fine roots to basal area decreased with stand development. Future research is needed to understand the actual effect of surface area and N content of fine roots on the maintenance of aboveground organs.

Biomass and morphological characteristics of fine roots and their affecting factors in diffe-rent vegetation restoration stages in depressions between karst hills

This study focused on four vegetation restoration stages of grasslands, shrublands, secondary forests and primary forests in the typical karst peak-cluster depression. The soil core method was used to collect fine roots with 2 mm or less in diameter in three layers (0-10, 10-20, 20-30 cm). The biomass, morphological characteristics of fine roots and their relationship with soil properties were analyzed. The results showed that fine root biomass ranged between 194.63 and 255.19 g·cm-2 in different vegetation restoration stages. Most of fine roots distributed in the surface soil of 0-10 cm, which accounted for more than 60% of the total biomass in the soil layer of 0-30 cm. No significant difference was found among different stages in fine root biomass. There was significant difference among different stages in the specific root length and specific surface area of fine roots. Both parameters were gradually decreased with vegetation forward restoration from grassland to primary forest. More than 66% root length and 64% root area were distributed in the surface soil of 0-10 cm. The length and area of most of the fine root were in the diameter class of 0-0.5 mm and 0.5-1mm, respectively. These two levels of the root length and root area accounted for more than 87% and 72% of the total amount, respectively. Results from the redundancy analysis showed that there were different correlations between karst peak-cluster depression vegetation community characteristics and soil properties, with soil organic carbon, available potassium, and total nitrogen having a great influence on the characteristics of fine roots. It is an effective strategy for plants to better adapt to the habitats.

武夷山不同海拔黄山松细根碳、氮、磷化学计量特征对土壤养分的适应

PDF HTML阅读 XML下载 导出引用 引用提醒 武夷山不同海拔黄山松细根碳、氮、磷化学计量特征对土壤养分的适应 DOI: 10.5846/stxb201701040034 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（31722007，31370589）；福建省自然科学基金项目（2015J01123）；福建省青年拔尖人才支持计划；国家重点研发计划课题（2017YFC0505400） Response of fine root carbon, nitrogen, and phosphorus stoichiometry to soil nutrients in Pinus taiwanensis along an elevation gradient in the Wuyi mountains 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:细根的生态化学计量特征承载着植物生存环境的变化信息，从而为探索全球变化对植物内在机制的影响提供理论依据。以江西武夷山国家级自然保护区内五个不同海拔梯度（1200、1400、1600、1800、2000 m）的黄山松为对象，运用挖掘法采样后测定细根C、N、P含量及化学计量比特征，研究不同的海拔下细根对土壤养分变化的适应规律。结果表明：（1）黄山松细根C含量年平均值为（486.27±64.32）mg/g，海拔对其没有显著的影响，与土壤养分之间不存在显著的相关关系。（2）细根N含量年平均值为（9.26±2.09）mg/g，海拔对其没有显著的影响，但与土壤C含量存在显著的正相关关系。（3）细根P含量年平均值为（0.39±0.13）mg/g，与海拔梯度及土壤P含量均存在极显著正相关关系，而与土壤碳氮比呈显著负相关关系。（4）细根氮磷比为26.94±12.51，与海拔梯度、土壤P含量及土壤碳氮比均显著负相关。因此，黄山松细根吸收N是以消耗C为代价；细根P主要受土壤P供应量的限制；武夷山地区N沉降将进一步增加植物的氮磷比，加剧黄山松生长的P限制。 Abstract:The ecological stoichiometric characteristics of fine roots reflect environmental changes. Thus, they provide a theoretical basis to explore the mechanisms of global changes affecting plants. The objective of the present study was to analyze the stoichiometry of Pinus taiwanensis is fine roots inhabiting five different elevation gradients (i.e., 1,200, 1,400, 1,600, 1,800, and 2,000 m) in Wuyishan National Nature Reserve. The fine roots were collected and the carbon (C), nitrogen (N), and phosphorus (P) concentrations and stoichiometric characteristics were analyzed. The results showed that:(1) The annual average C concentration of fine roots was (486.27±64.32) mg/g, and was not significantly affected by elevation. There was no significant correlation between the C concentration of fine roots and soil nutrients; (2) The annual average N concentration of fine roots was (9.26±2.09) mg/g, and was not significantly affected by elevation. But, there was a close correlation between the N concentration of fine roots and C concentration of soils; (3) The annual average P concentration of fine roots was (0.39±0.13) mg/g, which was closely correlated with altitude gradients and soil P contents, but negatively correlated with the soil C:N ratio; (4) The annual average N:P ratio of fine roots was 26.94±12.51, which was negatively correlated with altitude, soil P concentration, and the soil C:N ratio. Therefore, fine roots absorb N at the expense of C, fine root P is primarily limited by soil P supply, which would be further exacerbated by N deposition in the Wuyi Mountains. 参考文献 相似文献 引证文献