Fine Root Samples Research Articles

Fine roots of Scots pine and European beech respond differently to changes in nutrient availability in a mixed forest: results from a 4-year experiment

Abstract A nutrient availability experiment was carried out for four years in a mature mixed stand of Pinus sylvestris and Fagus sylvatica in the South-western Pyrenees mountains. Initial homogeneous pine regeneration (~58 years ago) was followed by uneven beech regeneration (~45 years ago), leading to the current successional stage in which areas resembling pine monospecific stands are at close distances and under comparable environmental conditions to mixed pine−beech areas. Soil and fine root samples were collected beside trees under three soil nutrient availability treatments: control, litter exclusion, and nitrogen-phosphorus-potassium (NPK) fertilization. Soil samples were collected twice a year (in May and October from 2017 to 2020), and fine root samples were collected twice (in May 2018 and May 2020). Soil fertilization had a bigger impact than litter exclusion on soil chemical parameters, leading to lower pH and NH4+ values. Also, increases in soil total nitrogen, soil available phosphorus, and microbial phosphorus were found after fertilization. Scots pine showed overall lower fine root biomass, specific root length, and root tissue density than beech, presenting also very little response to treatments. On the other hand, beech showed higher biomass and specific root length, but, when soil fertility was enhanced, lower root tissue density was recorded. A negative beech effect over pine fine root biomass was observed, as pine root presence decreased when growing near beech trees in mixed areas. Beech trees not only demonstrated an elevated capability to compete for soil resources but also showed greater root plasticity than pine, enhancing beech potential to take advantage of new soil resources. Our results do not support a complementary niche partitioning but rather a competitive interaction in which European beech has an edge on colonizing the soil volume in the detriment of Scots pine.

Distribution and characterization of endophytic and rhizosphere bacteriome of below-ground tissues in Chinese fir plantation.

Plantations of Chinese fir, a popular woody tree species, face sustainable issues, such as nutrient deficiency and increasing disease threat. Rhizosphere and endophytic bacteria play important roles in plants' nutrient absorption and stress alleviation. Our understanding of the microbiome structure and functions is proceeding rapidly in model plants and some crop species. Yet, the spatial distribution and functional patterns of the bacteriome for the woody trees remain largely unexplored. In this study, we collected rhizosphere soil, non-rhizosphere soil, fine root, thick root and primary root samples of Chinese fir and investigated the structure and distribution of bacteriome, as well as the beneficial effects of endophytic bacterial isolates. We discovered that Burkholderia and Paraburkholderia genera were overwhelmingly enriched in rhizosphere soil, and the abundance of Pseudomonas genus was significantly enhanced in fine root. By isolating and testing the nutrient absorption and pathogen antagonism functions of representative endophytic bacteria species in Pseudomonas and Burkholderia, we noticed that phosphorus-solubilizing functional isolates were enriched in fine root, while pathogen antagonism isolates were enriched in thick root. As a conclusion, our study revealed that the endophytic and rhizosphere environments of Chinese fir hold distinct structure and abundance of bacteriomes, with potential specific functional enrichment of some bacterial clades. These findings assist us to further study the potential regulation mechanism of endophytic functional bacteria by the host tree, which will contribute to beneficial microbe application in forestry plantations and sustainable development.

Fungi associated with fine roots of Fraxinus excelsior affected by ash dieback detected by next-generation sequencing

AbstractThe decline of European ash by dieback caused by Hymenoscyphus fraxineus together with stem collar necroses and rots caused by various fungi has been investigated intensively during the last years. Nevertheless, hitherto nearly nothing is known about the species diversity of the fungal rhizobiome of ash trees. Here we investigated the fine roots of affected ash trees on 15 sampling sites in 6 federal countries of Germany. Fine-root samples have been treated in three different sample regimes each as root-adhering soil, unsterilized fine roots and sterilized fine roots. The samples of trees in sampling sites were pooled to get an overview of the species-richness in the area. The next-generation sequencing platform Oxford Nanopore MinION was used to sequence the entire ITS of pooled probes. Most abundant phyla in all samples were the Basidiomycota and Ascomycota. Species richness in sterilized roots was significantly different from unsterilized roots and root-adhering soil. Surprisingly most abundant genera in sterilized roots were the genera Mycena, Mycenella and Delicatula, all of them agaricoids with saprophytic lifestyle. Eleven genera of Glomeromycota have been detected in various abundances, whereas the detection of H. fraxineus was neglectable.

Effects of nursery production methods on fungal community diversity within soil and roots of Abies alba Mill.

The aim of this study was to elucidate how different nursery production methods influence the composition of and relationship between soil and root community levels of Abies alba. In the Międzylesie Forest District, we quantified the responses of samples of both community-level fine roots and surrounding soil to environmental changes evoked by various seedling production methods. Fungi levels were identified based on their ITS 1 region and 5.8 S rDNA component. Analysis was conducted using Illumina SBS technology, and the obtained sequences were compared with reference samples deposited in the UNITE. Chemical analysis of the soil was also performed. Different nursery production methods resulted in a strong decoupling in the responses of fungal community levels between soil and roots. Changes in growth conditions imposed by production methods were significant in determining species composition. We found differences in fungal communities among functional groups of samples. In the soil, the dominant species of mycorrhizal fungi were Tylospora asterophora, Amanita rubescens, and Russula ionochlora. Mycorrhizal fungi in roots included Tuber anniae, Thelephoraceae sp., and Acephala applanata. Specific soil substrate conditions significantly influenced fungal community composition, leading to an increase in abundance of mycorrhizal fungi, specifically T. anniae.

Effects of forest types on soil carbon content in aggregate faction under climate transition zone

Variations in soil aggregates and soil organic carbon (SOC) in response to land-use change are important to understanding the carbon cycle in forest ecosystems. However, few studies investigated the effect of forest type on aggregate stability, SOC content, and particulate organic carbon (POC) content. Therefore, we collected soil and fine root samples in two natural forests (Pinus massoniana and Quercus variabilis) and a planted forest (Cunninghamia lanceolata) in a warm temperate–subtropical climate transition zone to analyze the effect of forest type on aggregate stability, SOC content, and POC content. The results showed that the mean weight diameter (MWD) of the soil aggregates was significantly higher in Quercus variabilis and Pinus massoniana forests (62% and 21%, respectively) than in the Cunninghamia lanceolata forest due to higher mycelial length density, mycelial infection rate, and glomalin content. Similarly, the SOC and POC contents were significantly higher in Quercus variabilis and Pinus massoniana forests than in the Cunninghamia lanceolata forest (p < 0.05). The dominant size fraction of aggregate was highly correlated with the carbon fraction content. The SOC and POC contents and fungal traits (mycelial length density, mycelial infection rate, and glomalin content) were significantly positively correlated with the MWD. These results indicated that natural forests had higher aggregate stability than planted forests due to higher SOC content and more favorable fungal traits in the warm temperate–subtropical climate transition zone.

马尾松和杉木人工林细根碳氮磷化学计量特征随土层深度的变化

PDF HTML阅读 XML下载 导出引用 引用提醒 马尾松和杉木人工林细根碳氮磷化学计量特征随土层深度的变化 DOI: 10.5846/stxb202203250740 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 福建省杰出青年基金项目滚动资助项目(2014J07005) Variation of carbon, nitrogen and phosphorus stoichiometric characteristics of fine roots in Masson pine and Chinese fir plantations with soil depth Author: Affiliation: Fund Project: Fujian Outstanding Youth Rolling Grant Project (2014J07005) 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:为探究马尾松和杉木人工林细根碳(C)、氮(N)、磷(P)浓度及其化学计量比随土层深度变化的特征,于2011年4月在福建省三明市金丝湾森林公园陈大林业采育场内测定马尾松和杉木人工林五个土层深度(0-10 cm、10-20 cm、20-40 cm、40-60 cm、60-80 cm)细根的C、N、P浓度、比根长(SRL)及其土壤养分浓度,结果表明:林分类型显著影响细根C浓度,但对细根N、P浓度无显著影响,马尾松人工林细根C浓度显著大于杉木人工林。土层深度显著影响马尾松和杉木人工林细根N、P浓度,对C浓度无影响,细根N、P浓度随土壤深度的增加呈指数下降。马尾松和杉木人工林细根N、P浓度与土壤全氮(TN)、全磷(TP)浓度以及SRL均呈正相关。拟合直线表明马尾松人工林和杉木人工林细根N养分获取能力的不同,马尾松对N养分的获取能力更强,而杉木通过SRL获取养分的能力比马尾松更强,可能体现了两种人工林细根N获取策略的差异。马尾松和杉木人工林在不同土层细根N ∶ P比值(33.5±2.81、30.18±2.10)均大于16,表明两者均受P限制,但细根N ∶ P不受土壤N ∶ P和SRL的影响。马尾松和杉木人工林细根N和P浓度受土层深度的影响,与土壤养分和细根形态特征变化有关。 Abstract:In order to examine the characteristics of fine root carbon (C), nitrogen (N), and phosphorus (P) concentrations and their stoichiometric ratios changing with soil depth in Masson pine (Pinus massoniana) and Chinese fir (Cunninghamia lanceolata) plantations, the experiments were conducted in April 2011, in Jinsiwan Forest Park, Sanming City, Fujian Province. The samples of fine roots in five soil depths (0-10 cm, 10-20 cm, 20-40 cm, 40-60 cm, 60-80 cm) of Masson pine and Chinese fir plantations were collected in the big forestry breeding farm to determine C, N and P concentration as well as specific root length (SRL). Soil nutrient contents were also measured. The results showed that forest type significantly influenced fine root C concentration, but not fine root N and P concentration, and that fine root C concentration was significantly greater in the plantation of Masson pine than in the plantation of Chinese fir. Soil depth significantly influenced fine root N and P concentrations, but not C concentrations, and fine root N and P concentrations decreased exponentially with increasing soil depth in both pinus sylvestris and fir plantations. Fine root N and P concentrations were positively correlated with soil Total nitrogen (TN) and Total phosphorus (TP) concentrations as well as SRL in both Horsetail Pine and Fir plantations. The fitted straight lines indicated the difference in the fine root N nutrient acquisition capacity between horsetail pine and fir plantations, with horsetail pine having a greater ability to acquire N nutrients and fir having a greater ability to acquire nutrients through SRL than horsetail pine, possibly reflecting the difference in fine root N acquisition strategies between the two plantations. The fine root N ∶ P ratios (33.5±2.81 and 30.18±2.10) of both horsetail pine and fir plantations were greater than 16 in different soil layers, indicating that both were P-limited, but fine root N ∶ P was not influenced by soil N ∶ P and SRL. Fine root N and P concentrations in plantations of horsetail pine and fir were influenced by soil depth and were related to changes in soil nutrients and fine root morphological characteristics. 参考文献 相似文献 引证文献

SEA-LEVEL RISE AND SETTLEMENT AT EK WAY NAL: CORING THE PAST

Excavations in the spring and summer of 2022 were carried out at the underwater ancient Maya salt work of Ek Way Nal in Punta Ycacos Lagoon, Paynes Creek National Park, Belize. Ek Way Nal provided salt to the ancient Maya during the Late and Terminal Classic periods (600-900 C.E.). In additional to excavations in buildings at the site, a 1 X 2 m unit was excavated to extract a sediment column for examining the relationship between the ancient Maya settlement at Ek Way Nal and sea-level rise. In this article, the excavations, extraction of the sediment column, and processing it for laboratory analyses are described. Field observations are discussed. Fine red mangrove root (Rhizophora mangle) and charcoal samples were extracted from the sediment column for radiocarbon dating. The results from the datum core excavation indicate that sea-level rise occurred before, during, and after the ancient Maya occupation at Ek Way Nal.

Effect of planting density on root biomass and distribution, and soil organic carbon stock of Acacia decurrens stands in Northwestern Ethiopia

Background:The expandingAcacia decurrenswoodlots in Northwestern Ethiopia is recognized for carbon storageviaroot biomass and soil organic carbon (SOC) enhancement but its planting densities have varied considerably. This study evaluated the effect of planting density on the root biomass, SOC stock, and vertical distributions in the stands.Methods:Five planting densities (0.5 m x 0.5 m, 0.75 m x 0.75 m, 1 m x 1 m, 1.25 m x 1.25 m, and 1.5 m x 1.5 m) were replicated four times with randomized complete block design. Soil core (6.67 cm diameter) and pit (900 cm2area) methods were used to collect fine and coarse root samples within 0–50 cm soil depth (having five soil layers in 10 cm intervals), respectively. Fine root biomass samples were classified as live and dead (necromass) and further as tree and herbaceous root. All root biomass samples were washed, oven-dried, weighed, and standardized into gram per meter square (g m-2) for root biomass comparisons for each planting density and soil depth, then summed up for 0–50 cm depth as a total root biomass. The vertical distributions of fine and coarse root biomass at each depth were expressed as a percentage (in decimal) of the total root biomass (0–50 cm).Conclusions:Planting density had significant effects on root biomass, SOC stock, and root distributions (P < 0.05) but inconsistent for the percentage of SOC stock at all soil layers except at 40-50 cm. PlantingA. decurrenswith high density is recommended to increase root biomass, SOC, and percentage of roots in deep soil layers. Further study is suggested for the effects of stand age on root biomass dynamics and SOC stock with large scale.

Linking rhizospheric microbial and fine root C:N:P stoichiometry under long-term forest conversion

The rhizosphere is the microbial hotspot, while fine roots (diameter <2 mm) are the most physiologically active component in forests. However, how rhizospheric microbial carbon (C): nitrogen (N): phosphorus (P) stoichiometry (ESm) is linked with fine root C:N:P stoichiometry (ESfr) in response to long-term forest conversion remains largely unexplored. Using a space-for-time substitution method, we investigated long-term conversion from natural forests (NF) to plantations of Metasequoia glyptostroboides (MG), Cryptomeria fortunei (CF) and Cunninghamia lanceolata (CL). Fine root and rhizospheric soil samples (0–10 cm depth) were collected, and their C, N and P contents were determined. The rhizospheric soil microbial community (SMC) structure, as well as microbial biomass C, N and P, was measured. Both ESm and ESfr present strict homeostasis and ESm did not significantly correlated with the SMC structure or the microenvironment, suggesting that C and nutrient processes via fine roots and rhizospheric microbes return to equilibrium after long-term forest conversion. Moreover, ESm was synergistically and tightly linked with ESfr, indicating that P deficiency was aggravated during NF-to-CF conversion but ameliorated during NF-to-MG and NF-to-CL conversions. The linkage between ESm and ESfr could act as a robust ecological indication of nutrient-use strategies and limitations in forest ecosystems, benefiting our understanding on C and nutrient cycling regarding forest management.

Soil properties and fine root morphological traits in relation to soil particle-size fractions in a broad-leaved beech (Fagus orientalis Lipsky) forest

Soil particle-size fractions play an important influence soil physico-chemical properties, microbial biomass processes as well as fine roots morphological traits in beech forest ecosystem. The objectives of study were to determine how soil texture interacts with soil physico-chemical properties and microbial biomass as well as fine roots traits in oriental beech forest in Guilan province, northern Iran. Five subplots of 400 m 2 were randomly selected at a plot of 1 ha. At five different locations, soil samples were collected at depth of 0–20 cm and fine root samples were also taken from beech trees. Results indicated that clay content was positively correlated with carbon, carbon/nitrogen (C/N) ratio, and moisture, but negatively correlated with nitrogen (N) and phosphorous (P). Silt values had significant positive correlation with C/N, and negative correlation with N and P. The microbial biomass carbon/carbon (MBC/C) ratio in soil increased significantly with clay, but microbial biomass nitrogen (MBN) decreased significantly with increasing clay. The MBC/C ratio decreased significantly with sand values in soil at depth 0–20 cm. Results showed that silt value of soil profile was negatively correlated with MBN, but positively with MBN/N ratio. Soil acidic phosphatase concentration was negatively correlated with clay content, but soil alkaline phosphatase was positively correlated with silt. Clay and sand contents were positively correlated with fine root density, fine root biomass, fine root length, and surface root area. Sand content was negatively correlated with fine root volume. The results of research, considering the correlation between soil particle-size fractions and some soil characteristics as well as fine root traits, show that soil texture in oriental beech forest can play an important role in forest stand dynamics. • The clay content was positively correlated with C, C/N ratio, and moisture. • Clay and sand fractions were positively related to some fine root traits. • 3.The MBC/C ratio in soil increased significantly with increasing clay amount.

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

Abstract 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.

Factors of Carbon and Nitrogen Contents in the Fine Roots of Plants in the Middle Urals

Abstract—Some factors influencing C and N contents in fine plant roots were studied in the Middle Urals. They included ecological (edaphic) features of habitats; type of root symbioses (the capability for symbiotic nitrogen fixation and formation of different mycorrhiza types); and ecological strategies of species. Samples of fine roots from woody and herbaceous plants and of the upper soil layer were collected in two industrial dump sites and in an area with natural communities. In each area, samples were taken from forest and meadow habitats. The content of C or N in the species from the sampling plot served as an observation unit. A total of 83 estimates were analyzed. As a result, differences were revealed between the key factors influencing the content of each element in fine roots: the C content is determined mainly by the type of mycorrhiza, while the determinant factor for the N content is the capability for symbiotic nitrogen fixation; ecological features of habitats and the type of plant ecological strategy are the second and third factors influencing the C and N contents. The patterns of N accumulation in the roots of plants with different ecological strategies and with different types of mycorrhizas do not fully replicate the patterns of N accumulation in their leaves.

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.

Belowground fungal community diversity, composition and ecological functionality associated with winter wheat in conventional and organic agricultural systems.

Understanding the impacts of agricultural practices on belowground fungal communities is crucial in order to preserve biological diversity in agricultural soils and enhance their role in agroecosystem functioning. Although fungal communities are widely distributed, relatively few studies have correlated agricultural production practices. We investigated the diversity, composition and ecological functionality of fungal communities in roots of winter wheat (Triticum aestivum) growing in conventional and organic farming systems. Direct and nested polymerase chain reaction (PCR) amplifications spanning the internal transcribed spacer (ITS) region of the rDNA from pooled fine root samples were performed with two different sets of fungal specific primers. Fungal identification was carried out through similarity searches against validated reference sequences (RefSeq). The R package ‘picante’ and FUNGuild were used to analyse fungal community composition and trophic mode, respectively. Either by direct or cloning sequencing, 130 complete ITS sequences were clustered into 39 operational taxonomic units (OTUs) (25 singletons), belonging to the Ascomycota (24), the Basidiomycota (14) and to the Glomeromycota (1). Fungal communities from conventional farming sites are phylogenetically more related than expected by chance. Constrained ordination analysis identified total N, total S and Pcal that had a significant effect on the OTU’s abundance and distribution, and a further correlation with the diversity of the co-occurring vegetation could be hypothesised. The functional predictions based on FUNGuild suggested that conventional farming increased the presence of plant pathogenic fungi compared with organic farming. Based on diversity, OTU distribution, nutrition mode and the significant phylogenetic clustering of fungal communities, this study shows that fungal communities differ across sampling sites, depending on agricultural practices. Although it is not fully clear which factors determine the fungal communities, our findings suggest that organic farming systems have a positive effect on fungal communities in winter wheat crops.

C:N:P stoichiometry of leaves and fine roots in typical forest swamps of the Greater Hinggan Mountains, China

Investigating ecological stoichiometry of leaves and fine roots of forest swamps in the Greater Hinggan Mountains will improve our understanding of plant nutrient use and material cycling in ecosystems at high latitudes with high sensitivity to climate change. In this study, we collected leaf and fine root samples from 19 dominant and subordinate vascular plant species and measured their C, N and P concentrations in three typical forest swamps (Larix gmelinii-Carex schmidtii, L. gmelinii-Vaccinium uliginosum-moss and L. gmelinii-Ledum palustre-Sphagnum) of the Greater Hinggan Mountains, China. We compared C:N:P stoichiometry in leaves and fine roots among different forest swamp types, plant growth forms, and mycorrhizal types. Standardized major axis regression was performed to examine the relationships between leaf and fine root stoichiometry. The results showed that interspecific variation accounted for the largest proportion of total variation in C:N:P stoichiometry of leaves (42.5%-84.6%). N:P had the highest, C:N had the intermediate, and C:P had the lowest interspecific variation in both leaves and fine roots. L. gmelinii-C. schmidtii forest swamps, which had higher soil nutrient and water availability, had lower C:N and C:P in leaves and fine roots. N:P of all three forest swamps were lower than 10, indicating N limitation in this ecosystem. Herbaceous plants had significantly lower leaf C:P, fine root C:N, and fine root C:P than woody species. Both ectomycorrhizal and ericoid mycorrhizal plants had higher leaf and fine root C:N and C:P than arbuscular mycorrhizal and non-mycorrhizal species, while the C:P of ericoid mycorrhizal plants was significantly higher than that of ectomycorrhizal species. Forest swamp type, plant growth form, and mycorrhizal type all had greater influences on leaf and fine root C:N and C:P rather than N:P. Leaf and fine root C:N, C:P, and N:P were positively correlated, indicating strong coordination between plant above- and below-ground C:N:P stoichiometry.

Sample size estimation for achieving the desired uncertainty for estimates of tree fine root trait parameters

This study investigates efficient strategies for fine tree root sampling, in terms of estimating root trait parameters with desired confidence intervals for least effort and cost. Sampling tree roots is difficult and costly with high variation among samples and wide confidence intervals for parameter estimates. Efficient strategies for fine tree root sampling will estimate root trait parameters with the desired confidence interval for least effort and cost. We compared alternative strategies to sample and estimate fine root surface area density; (1) collecting samples at intervals of 10 cm to a depth of 150 cm for entire tree root systems versus (2) independently taking samples from different randomly-selected 10-cm depth intervals around different trees. We also quantified the pilot sample size needed to reliably estimate the number of samples that would achieve the desired confidence interval. Efficiency of sampling entire tree root systems versus independent samples depended on the structure of the sample data. Pilot sample sizes > 5 per 10-cm soil depth can give reliable estimates of sample sizes required to achieve a 95% confidence interval of ± 10% of the sample mean. The statistical strategies in this paper are not particularly novel or difficult, but are seldom applied to root studies. We contend that they should be used, both to guide efficiency in sampling design and also to assess how realistic it is to expect that estimated sample means will be reliable, in the sense of having confidence intervals of the required width.

Soil and fine roots ecological stoichiometry in different vegetation restoration stages in a karst area, southwest China

The cyclic process of carbon (C), nitrogen (N), and phosphorus (P) elements is an important factor affecting the function of the forest ecosystem. However, the relation between soil and root stoichiometric ratios, especially in karst areas with extremely fragile geology and intensive human disturbance has rarely been investigated. In the current study the concentrations of C, N, and P and their stoichiometric characteristics were investigated using sequential soil coring under different stages of vegetation restoration (primary forest, secondary forest, shrubland and grassland) and soil layer (0-10 cm, 10-20 cm, 20-30 cm) in fine root and soil samples. The results showed that total C concentration had no significant change in all four vegetation types and three soils layer in the fine root, whereas total N and P concentration reached the maximum value in secondary forest and the minimum in grassland. In addition, soil organic C (SOC) and total N increased continuously with natural succession and decreased with soil depth. Secondary forest showed the largest total P concentration in soil, with the smallest corresponding to grassland. Furthermore, both vegetation type and soil layer significantly affected soil C, N, and P stoichiometric ratios. There was a positive correlation among C, N and P in the fine roots, as well as in the soil. While fine root C:N and C:P ratios were negatively related to soil C:N and C:P, fine root N:P was significantly related to soil N:P. This study can provide a scientific basis for the restoration of fragile ecosystem vegetation and for comprehensive treatment of rocky desertification in karst.

Variation in the functional traits of fine roots is linked to phylogenetics in the common tree species of Chinese subtropical forests

The phylogenetic variations of fine root traits, which are related to plant growth and development as well as to physiological and ecological processes, are not fully understood. This study aimed to: (1) examine how tree species and sampling methodology affect the anatomical, morphological and nutrient traits of fine roots; and (2) determine whether phylogenetic signals affect fine root trait relationships and influence comparison of root traits between the branch order-based and diameter-based cut-off sampling categories. Fine root samples of 16 subtropical forest tree species were obtained and their anatomical, morphological and nutrient traits were studied. The phylogenetic signals of trait variations were calculated to determine trait relationships. Tree species and sampling methodology significantly affected fine root traits (p < 0.05). Mean root diameters, root tissue density (RTD) and carbon-to-nitrogen ratio were the lowest in the first-order category and highest in the ≤2 mm category. The reverse pattern was found for specific root length, specific root area and nitrogen concentration. Morphological traits showed significant phylogenetic signals; however, nutrient traits did not reflect phylogenetic conservatism. Phylogenetic factors influenced correlations between traits for the first-order root economics spectrum. Root traits were multidimensional and RTD was loaded on a novel phylogenetic principal component analysis. Functional traits of fine roots are multidimensional for subtropical tree species and closely linked to phylogeny. Morphological traits of first order roots showed a much stronger phylogenetic signal than those of roots ≤2 mm (traditionally defined fine roots). The findings improve understanding of root trait strategies in response to environmental changes.

Source of mycorrhizal inoculum influences growth of Faidherbia albida seedlings

Poor land use management and practice inhibit the growth and establishment of tree seedlings in dryland areas. We assessed arbuscular mycorrhizal fungi (AM) status of Faidherbia albida (Del.) A. Chev. trees grown on different land uses. We quantified the growth and nutrient uptake of F. albida seedlings inoculated with AM from different sources. These efforts were based on soil and fine root samples from the rhizosphere soils of F. albida trees. AM root colonization was determined using the gridline intersect method. Spores were extracted by the wet sieving and decanting method and identified to genus level. The seedling experiment had a completely randomized one-factorial design with four treatments and five replications. Faidherbida albida seedlings were grown in a greenhouse. All in situ F. albida trees were colonized by AM fungi. AM root colonization of F. albida trees was significantly higher (P < 0.0086) in area exclosures than on lands used for grazing or cultivation. Spore abundance was significantly higher (P < 0.0014) in area exclosures followed by cultivated land and grazing land. Glomus was the dominant genus in all land-uses. AM-inoculated F. albida seedlings grew better (P < 0.05) than non-inoculated controls. Seedlings inoculated with AM from area exclosure had significantly (P < 0.05) higher growth and nutrient uptake than those inoculated with AM from grazing and cultivated land. This emphasizes the importance of the native soil AM potential for better establishment of seedlings to achieve optimum plant growth improvement and assist in rehabilitation of degraded arid lands.

Microbial community response to growing season and plant nutrient optimisation in a boreal Norway spruce forest

Interactions between Norway spruce trees and bacteria and fungi in nutrient limited boreal forests can be beneficial for tree growth and fitness. Tree-level effects of anthropogenic nutrient additi ...