Root Decomposition Research Articles

Contrasting dynamics and factor controls in leaf compared with different-diameter fine root litter decomposition in secondary forests in the Qinling Mountains after 5 years of whole-tree harvesting

Plant litter decomposition is a crucial pathway for carbon (C) and nutrient cycling, and controls the net primary productivity in ecosystems worldwide. However, little is known about how multi-type litter (leaf and different diameter fine roots) decomposition rates and nutrient release change at the community level following whole-tree harvesting (WTH). In the present study, we followed decomposition of leaf and different diameter fine root (∅ < 0.5 mm, 0.5–1 mm, 1–2 mm) litters at plot level over 2 years in a secondary forest in the Qinling Mountains after 5 years of five different thinning treatments (0%, 15%, 30%, 45%, and 60%). Our results demonstrated that WTH had no effects on leaf and different diameter fine root litter decomposition at the plot level. Leaves had significantly higher decomposition rate than different diameter fine roots. There were significant positive correlations between decomposition rate of different diameter fine roots, but not related to leaf litter decomposition rate. WTH did not affect the nutrient release of leaf and different diameter fine root litters at the plot level. The nitrogen (N), phosphorous (P) and potassium (K) mass remaining in leaf litters were significantly higher than different diameter fine roots after 2 years decomposition, while different diameter fine roots had higher C mass remaining. Leaf and fine root litter decomposition rates were mainly influenced by stand and litter quality attributes. Nutrient release of leaf and fine root N, P and K were mainly predicted by litter quality characteristics, while there were no consistent driving factors for C release. Our results suggested that WTH had no effects on multi-type litter decomposition and nutrient release at plot level after 5 years of recovery. Moreover, leaf litters had excellent N, P and K nutrient preservation mechanisms, and C conservation in fine root litters.

The positive role of root decomposition on the bioremediation of organic pollutants contaminated soil: A case study using PCB-9 as a model compound

Root decomposition keeps occurring widely in soils, particularly after plant harvest and death, and drives critical microbial ecological functions. However, its role in the destiny of soil organic pollutants and underlying mechanisms remain unclear. In this study, DNA stable isotope probing (DNA-SIP) was combined with metabolomics to investigate the mechanisms of soil polychlorinated biphenyls (PCBs) degradation in the root decomposition process by identifying the active PCBs degraders in situ and corresponding metabolites. The 2,5-dichlorobiphenyl (PCB-9) degradation was improved by 7.4% in the root decomposition treatment relative to the rhizosphere treatment, and the degradation was faster in both treatments than the control after 6-week cultivation. Both root decomposition and rhizosphere treatments altered soil microbial community, changing the active PCB-9 degraders to different extents. The root decomposition treatment had the highest “average phylogenetic distance index” (ADI) value, indicating a competition reduction effect of root decomposition on microbial survival, and the lowest corrected average phylogenetic distance index (ADIC) value, suggesting a preference toward aerobic PCBs degraders during root decomposition. Metabolites associated with the root decomposition process critically affected both the whole microbial community and active PCB-9 degraders. Compounds related to carbohydrate and lipid metabolisms were enriched during the root decomposition process and might be important to the active PCB-9-degrading community assembly. Our results confirmed that root decomposition improved the biodegradation of organic pollutants in soil and reminded us of its importance in soil quality.

Methanotrophy Alleviates Nitrogen Constraint of Carbon Turnover by Rice Root-Associated Microbiomes.

The bioavailability of nitrogen constrains primary productivity, and ecosystem stoichiometry implies stimulation of N2 fixation in association with carbon sequestration in hotspots such as paddy soils. In this study, we show that N2 fixation was triggered by methane oxidation and the methanotrophs serve as microbial engines driving the turnover of carbon and nitrogen in rice roots. 15N2-stable isotope probing showed that N2-fixing activity was stimulated 160-fold by CH4 oxidation from 0.27 to 43.3 μmol N g–1 dry weight root biomass, and approximately 42.5% of the fixed N existed in the form of 15N-NH4+ through microbial mineralization. Nitrate amendment almost completely abolished N2 fixation. Ecophysiology flux measurement indicated that methane oxidation-induced N2 fixation contributed only 1.9% of total nitrogen, whereas methanotrophy-primed mineralization accounted for 21.7% of total nitrogen to facilitate root carbon turnover. DNA-based stable isotope probing further indicated that gammaproteobacterial Methylomonas-like methanotrophs dominated N2 fixation in CH4-consuming roots, whereas nitrate addition resulted in the shift of the active population to alphaproteobacterial Methylocystis-like methanotrophs. Co-occurring pattern analysis of active microbial community further suggested that a number of keystone taxa could have played a major role in nitrogen acquisition through root decomposition and N2 fixation to facilitate nutrient cycling while maintaining soil productivity. This study thus highlights the importance of root-associated methanotrophs as both biofilters of greenhouse gas methane and microbial engines of bioavailable nitrogen for rice growth.

Divergent responses of fine root decomposition to removal of understory plants and overstory trees in subtropical Eucalyptus urophylla plantations

Divergent responses of fine root decomposition to removal of understory plants and overstory trees in subtropical Eucalyptus urophylla plantations

Radar Target Tracking for Unmanned Surface Vehicle Based on Square Root Sage-Husa Adaptive Robust Kalman Filter.

Dynamic information such as the position and velocity of the target detected by marine radar is frequently susceptible to external measurement white noise generated by the oscillations of an unmanned surface vehicle (USV) and target. Although the Sage–Husa adaptive Kalman filter (SHAKF) has been applied to the target tracking field, the precision and stability of SHAKF remain to be improved. In this paper, a square root Sage–Husa adaptive robust Kalman filter (SR-SHARKF) algorithm together with the constant jerk model is proposed, which can not only solve the problem of filtering divergence triggered by numerical rounding errors, inaccurate system mathematics, and noise statistical models, but also improve the filtering accuracy. First, a novel square root decomposition method is proposed in the SR-SHARKF algorithm for decomposing the covariance matrix of SHAKF to assure its non-negative definiteness. After that, a three-segment approach is adopted to balance the observed and predicted states by evaluating the adaptive scale factor. Finally, the unbiased and the biased noise estimators are integrated while the interval scope of the measurement noise is constrained to jointly evaluate the measurement and observation noise for better adaptability and reliability. Simulation and experimental results demonstrate the effectiveness of the proposed algorithm in eliminating white noise triggered by the USV and target oscillations.

Decoupled responses of leaf and root decomposition to nutrient deposition in a subtropical plantation

The decomposition of leaf and root litter plays an important role in the cycling of nutrients and carbon (C) in ecosystems. The long-term patterns of mass loss during leaf and root decomposition are well documented, but the long-term responses of mass loss and C quality during the decomposition of these two types of litter to the simultaneous deposition of exogenous nitrogen (N) and phosphorus (P) are not known. We compared the responses of the rate of mass loss, C quality, and the enzymatic and chemical properties of root and leaf litters in the early and late phases of decomposition to N and P addition in a subtropical plantation. N and P addition had delayed effects on root decomposition compared with leaf decomposition. The addition of N and P promoted leaf decomposition in the early phase likely by alleviating the P limitation of microorganisms, indicated by the higher P concentration and lower N/P ratio. The addition of N and P, however, stimulated the decomposition of root litter in the late phase, which was associated with increases in the concentrations of manganese and P in the root residues. The addition of N and P decreased the C quality of the leaf residue in the late phase but had little effect on the C quality of the root residue, even though N and P addition decreased the activity of acid phosphatase and increased the ratio of activities of β-glucosidase to acid phosphatase in the root residue. The decoupled responses of mass loss and C quality during leaf and root decomposition to N and P addition highlight the need to distinguish between leaf and root litter in the late phase of decomposition when evaluating the impact of atmospheric N and P deposition on the cycling of C and nutrients.

Mowing Facilitated Shoot and Root Litter Decomposition Compared with Grazing

Shoot and root litter are two major sources of soil organic carbon, and their decomposition is a crucial nutrient cycling process in the ecosystem. Altitude and land use could affect litter decomposition by changing the environment in mountain grassland ecosystems. However, few studies have investigated the effects of land use on litter decomposition in different altitudes. We examined how land-use type (mowing vs. grazing) affected shoot and root litter decomposition of a dominant grass (Bromus inermis) in mountain grasslands with two different altitudes in northwest China. Litterbags with 6 g of shoot or root were fixed in the plots to decompose for one year. The mass loss rate of the litter, and the environmental attributes related to decomposition, were measured. Litter decomposed faster in mowing than grazing plots, resulting from the higher plant cover and soil moisture but lower bulk density, which might promote soil microbial activities. Increased altitude promoted litter decomposition, and was positively correlated with soil moisture, soil organic carbon (SOC), and β-xylosidase activity. Our results highlight the diverse influences of land-use type on litter decomposition in different altitudes. The positive effects of mowing on shoot decomposition were stronger in lower than higher altitude compared to grazing due to the stronger responses of the plant (e.g., litter and aboveground biomass) and soil (e.g., soil moisture, soil bulk density, and SOC). Soil nutrients (e.g., SOC and soil total nitrogen) seemed to play essential roles in root decomposition, which was increased in mowing plots at lower altitude and vice versa at higher altitude. Therefore, grazing significantly decreased root mass loss at higher altitude, but slightly increased at lower altitude compared to mowing. Our results indicated that the land use might variously regulate the innate differences of the plant and edaphic conditions along an altitude gradient, exerting complex impacts in litter decomposition and further influencing carbon and nutrient cycling in mountain grasslands.

Drought Impacts on Tree Root Traits Are Linked to Their Decomposability and Net Carbon Release

Root trait plasticity can facilitate plant adjustment to water shortages, but the impact of altered traits on belowground carbon (C) cycling is mostly unknown. While drought and nutrient availability can alter root morphological and chemical traits that may affect root decomposition, direct assessments of drought mediated changes on decomposability are not available. We exposed four tree species contrasting in drought stress tolerance and root traits to three dry-down and recovery periods (over 5 months after 11 months of growth in well-watered conditions) under high and low nutrient conditions. We then assessed early stage root decomposability in relation to their morphology and chemistry as well as implications for CO2 release when accounting for effects on root biomass. While each species showed a unique set of responses, drought generally reduced root diameter and increased nitrogen concentration. We found limited evidence that morphological responses to drought were counteracted by high nutrient supply. Results indicated that the degree of association between morphological and nutrient root trait responses to drought and decomposability varied with different species. However, across these contrasting woody species, drought-induced increases in nitrogen and phosphorus concentrations were associated with drought-induced increases in early stage root decomposability. When accounting for changes in root biomass, estimated overall C loss through root decomposition increased with drought stress. Our experimental results demonstrate that changes in tree root traits with drought can enhance C loss via root decomposition, and with other factors being equal, drought may potentially contribute to a positive feedback to climate change. Our findings contribute empirical evidence to help disentangle the multiple factors involved in root contribution to C balances at the ecosystem level.

Functional Links between Biomass Production and Decomposition of Vetiver (Chrysopogon zizanioides) Grass in Three Australian Soils.

Plant roots are primary factors to contribute to surface and deep soil carbon sequestration (SCS). Perennial grasses like vetiver produce large and deep root system and are likely to contribute significantly to soil carbon. However, we have limited knowledge on how root and shoot decomposition differ and their contribution to SCS. This study examined biomass production and relative decomposition of vetiver which was grown under glasshouse conditions. Subsequently the biomass incubated for 206 days, and the gas analysed using ANCA-GSL. The results confirmed large shoot and root production potential of 161 and 107 Mg ha−1 (fresh) and 67.7 and 52.5 Mg ha−1 (dry) biomass, respectively with 1:1.43 (fresh) and 1:1.25 (dry) production ratio. Vetiver roots decomposed more rapidly in the clay soil (p < 0.001) compared with the shoots, which could be attributed to the lower C:N ratio of roots than the shoots. The large root biomass produced does indeed contribute more to the soil carbon accumulation and the faster root decomposition is crucial in releasing the carbon in the root exudates and would also speed up its contribution to stable SOM. Hence, planting vetiver and similar tropical perennial grasses on degraded and less fertile soils could be a good strategy to rehabilitate degraded soils and for SCS.

Potential effects of sea level rise on decomposition and nutrient release of dead fine roots in a Kandelia obovata forest

Fine roots play an important role in the carbon dynamics and nutrient cycles of mangroves. Mangrove forests are threatened by sea level rise (SLR). Therefore, it is critical to understand how SLR affects dynamics of decomposition and nutrient release of dead fine roots to evaluate carbon dynamics and nutrient cycles of mangroves. Dynamics of decomposition and nutrient release of dead fine roots were compared among three sites under different intertidal elevations in a 11-year-old Kandelia obovata mangrove forest, representing tidal flooding situation of SLR values of 0, 40 and 80 cm, respectively. Mangroves at site SLR 80 cm had the highest dry weight loss of dead fine roots in the 10 and 30 cm soil layers. Mean rate of decomposition (MRD) at site SLR 80 cm was significantly higher than those at other sites, increasing by approximately 0.48 and 0.27 mg gDW−1 d−1 in the 10 cm and 30 cm soil layers due to SLR 80 cm, respectively. Site SLR 80 cm had significantly higher organic carbon (OC) losses of dead fine roots and OC loss percentages in the 10 cm soil layer than the other sites, while higher values were found at site SLR 40 cm in the 30 cm soil layer. Moreover, significantly higher nitrogen (N) losses of dead fine roots and N loss percentages were also found at site SLR 40 cm. These indicate that SLR will increase the rates of decomposition and release of nutrients of dead fine roots, which will accelerate carbon dynamics and nitrogen cycles of mangroves.

Root and Rhizosphere Processes under Drought: Digging Deeper to Enhance Ecosystem Resilience

Root and Rhizosphere Processes under Drought: Digging Deeper to Enhance Ecosystem Resilience

Fine root decomposition and nutrient release in two tropical forests of Central Himalaya: a comparative and factor controlling approach

Fine root decomposition and nutrient release in two tropical forests of Central Himalaya: a comparative and factor controlling approach

Impacts of alpine shrub-meadow degradation on its ecosystem services and spatial patterns in Qinghai-Tibetan Plateau

• UAV is used to detect the spatial pattern of alpine shrub-meadow degradation. • Ecosystem services changes in degraded alpine shrub meadow are non-linear. • Spatial pattern characteristics may fail to interpret ecosystem service changes. Alpine shrub-meadow is an important ecosystem type on the Qinghai-Tibetan Plateau, providing a variety of ecosystem services while supporting the livelihoods of pastoralists. However, there is a clear lack of understanding of the changes in spatial patterns and ecosystem services of alpine shrub-meadow degradation. This study combined aerial photography and ground surveys to investigate and analyse the impact of degradation on the spatial patterns of alpine shrub-meadow and their ecosystem services, and the relationships between the spatial patterns and ecosystem services. The results showed that degradation led to fragmentation and patchiness in alpine shrub-meadow, as evidenced by a decrease in the proportion of shrub and meadow area and average patch size, as well as the complexity of patch boundaries and shapes. Light and moderate degradation reduced all ecosystem services in alpine shrub-meadow, with carbon storage, nutrient supply and water retention services decreased by an average of 27.4%, 17.3% and 13.8% respectively, while forage supply services decreased by 65.2% at heavy degradation, and the reduction in alpine meadow ecosystem services was even greater. Regulating services increased again at heavy degradation due to the accumulation and slow decomposition of plant underground roots, and rodent activity. The spatial patterns of the meadow layer were more closely related to its ecosystem services than the shrub layer, and fragmentation and patchiness were positively related to ecosystem services. Our findings suggest that the impact of degradation on alpine shrub-meadow ecosystem services may be non-linear and that the relationships between spatial patterns and ecosystem services need to be interpreted with caution and should be analysed comprehensively with a wider range of influencing factors. Our results have implications for grassland restoration and ecosystem service management on the Qinghai-Tibetan Plateau.

Soil pore architecture and rhizosphere legacy define N2O production in root detritusphere

Root detritusphere is one of the most important sources of N2O, however, understanding of how N2O emission from the detritusphere is influenced by soil properties remains elusive. Here, we evaluated the effects of pore architecture and soil moisture on N2O emission during the decomposition of in-situ grown roots of switchgrass, an important bioenergy crop. We combined dual isotope labeling (15C and 15N) with zymography to gain insights into the location of the microbial N2O production in soils with contrasting pore architectures. In the studied soil, the effect of soil pore architecture on N2O emissions was 6 times greater than that of soil moisture. Soil dominated by > 30 μm Ø pores (i.e., large-pore soil) had higher chitinase activity than the soil dominated by < 10 μm Ø pores (i.e., small-pore soil), especially near the decomposing roots. The chitinase activity on the decomposing roots was positively correlated with emission of root-derived N2O, indicating that N released from root decomposition was an important source of N2O. Greater N2O and N2 emission was induced by switchgrass roots in soils dominated by the large- compared to the small-pore soils. The microenvironment developed near decomposing roots of the large-pore soil also resulted in positive N2O priming. Our study challenged the traditional view on soil moisture as the main factor of N2O production. Production and emission of N2O was most intensive in microbial activity hotspots (i.e., rhizosphere legacy) in the large pores, where decomposed roots release mineral N as the main N2O source.

Net soil carbon balance in afforested peatlands and separating autotrophic and heterotrophic soil CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; effluxes

Abstract. Peatlands are a significant global carbon (C) store, which can be compromised by drainage and afforestation. Quantifying the rate of C loss from peat soils under forestry is challenging, as soil CO2 efflux includes both CO2 produced from heterotrophic peat decomposition and CO2 produced by tree roots and associated fungal networks (autotrophic respiration). We experimentally terminated autotrophic below-ground respiration in replicated forest plots by cutting through all living tree roots (trenching) and measured soil surface CO2 flux, litter input, litter decay rate, and soil temperature and moisture over 2 years. Decomposition of cut roots was measured and CO2 fluxes were corrected for this, which resulted in a large change in the fraction heterotrophic : autotrophic flux, suggesting that even 2 years after trenching decaying root biomass makes significant contributions to the CO2 flux. Annual peat decomposition (heterotrophic CO2 flux) was 115 ± 16 g C m−2 yr−1, representing ca. 40 % of total soil respiration. Decomposition of needle litter is accelerated in the presence of an active rhizosphere, indicating a priming effect by labile C inputs from roots. This suggests that our estimates of peat mineralization in our trenched plots are conservative and underestimate overall rates of peat C loss. Considering also input of litter from trees, our results indicate that the soils in these 30-year-old drained and afforested peatlands are a net sink for C, since substantially more C enters the soil organic matter than is decomposed heterotrophically. This study does not account for fluvial C fluxes, which represent a small flux compared to the CO2 soil efflux; further, root litter and exudate deposition could be a significant C source that is only partially sampled by our approach, adding to these plantations being a potential carbon sink. However, the C balance for these soils should be taken over the lifespan of the trees, in order to determine if the soils under these drained and afforested peatlands are a sustained sink of C or become a net source over longer periods of forestry.

Fine root biomass stocks but not the production and turnover rates vary with the age of tropical successional forests in Southern Mexico

Fine root production, turnover, and decomposition are fundamental rhizosphere processes that can vary when young forest ecosystems pass through different phases of succession towards maturity. To assess these changes during succession, we applied ingrowth bag and sequential coring methods for fine root production and a modified negative exponential model for fine root decomposition at four phases of tropical forest chronosequence: 1) young secondary forests of about 8 years, 2) medium secondary forests of 15 years, 3) advanced secondary forests of 25 years, and 4) old-growth primary forests of >100 years. Primary forests stored higher fine root biomass than secondary forests but the average fine root productivity did not differ statistically between successional phases. Fine root turnover rates were >1 yr−1 for all the phases of succession, indicating that the turnover was higher than the standing fine root biomass. Fine root decay models showed that the decomposition rates did not differ significantly between successional phases. Furthermore, fine root production and mortality correlated positively to soil organic carbon concentrations. Our results showed that fine root productivity and turnover rates in secondary forests get to PF level from the younger phases of succession. The results have important implications in understanding the successional patterns regarding belowground resource allocation, nutrient turnover, and soil organic carbon sequestration in the constantly changing tropical forests ecosystems.

A Bibliometric Analysis of Global Fine Roots Research in Forest Ecosystems during 1992–2020

(1) Background: Fine roots (≤2 mm in diameter) play a critical role in forest ecosystem ecological processes and has been widely identified as a major research topic. This study aimed to synthesize the global literature based on the Web of Science Core Collection scientific database from 1992 to 2020 and summarize the research trends and prospects on research of fine roots in forest ecosystems. A quantitative bibliometric analysis was presented with information related to authors, countries, institutions, journals, top cited publications, research hotspots, trends, and prospects. (2) Results: The results showed that the amount of publications has increased exponentially. USA, China, and Germany were the most productive countries. Chinese Academy of Science was the most productive institution on fine roots research and also has a key position in both domestic and international cooperation networks. Leuschner C and Hertel D were the most productive authors. Six core journals were confirmed from 471 journals based on Bradford’s law. The distribution of the frequency of authors and the number of their publications were fitted with Lotka’s Law. Author collaboration network was mainly limited in the same countries/territories and institutions. Keywords analysis indicates that the hotspots are biomass, decomposition, and respiration of fine roots, especially under climate change. (3) Conclusion: Our results provide a better understanding of global characteristics and trends of fine roots that have emerged in this field, which could offer reference for future research.

Buried pipeline installation impacts on soil structure and crop root decomposition

AbstractThe severe manipulation of soil that occurs in the right‐of‐way (ROW) easement areas for pipeline installation leads to soil degradation and yield loss. The objectives of this study were to investigate the use of the Visual Evaluation of Soil Structure method (VESS) and root litter sampling as alternative ways to characterize pipeline installation impacts on soil degradation. Digital images of aggregate specimens and root samples were obtained from disturbed (trenched and highly trafficked ROW areas) and undisturbed (adjacent to the ROW) soil profiles one month after maize (Zea mays L.) harvest in Iowa. Images of soil aggregates indicated that pipeline installation deteriorated soil structure. Root attributes were significantly (p &lt; 0.05) affected by the ROW activities. The non‐decomposed root mass in the highly trafficked area (3,568 kg ha–1) was two times greater than the root mass in undisturbed soil (1,779 kg ha–1). These data provide evidence that soil structure quality and root decomposition rates are affected by soil disturbance. The VESS and root measurements can be used in future studies to evaluate the impacts of soil disturbance.

Interactions of Soil Nutrients and Soil Microbial Communities During Root Decomposition of Gramineous and Leguminous Forages

Interactions of Soil Nutrients and Soil Microbial Communities During Root Decomposition of Gramineous and Leguminous Forages

岩溶地区不同石漠化程度下草地细根对土壤养分的贡献

细根分解和周转是土壤有机质和养分的重要来源。为探明不同石漠化程度天然草地细根对土壤养分的贡献，于2017年3月至次年1月，采用土柱法和分解袋法，研究不同石漠化程度下天然草地的细根生物量、分解和养分释放动态及对石漠化的响应。结果表明：3种不同石漠化程度下草地的细根生物量随季节均呈现先增加后降低的趋势，随石漠化程度的加剧均呈现逐渐降低的趋势，潜在、中度和强度石漠化草地的细根生物量分别为3355.65、2944.02 g/m²和1806.80 g/m²。细根分解速率呈现先快后慢的趋势，分解300天后的残留率均低于50%。细根有机碳、全氮、全磷和全钾的释放过程具有显著不同，释放模式最终均表现为"释放"，潜在、中度和强度石漠化草地细根的有机碳、全氮、全磷、全钾的年归还量分别为32.46-161.08、0.24-3.88、0.08-0.32、0.15-2.78 g/m²。随石漠化程度的加剧，细根生物量和分解率呈现逐渐降低趋势，土壤有机碳、全氮归还量呈现逐渐增加趋势。;The degradation land of rocky desertification is one of the most serious problems on economic development, ecosystem restoration and reconstruction in Southwest China. Grassland is one of the main vegetation types in karst area, and its fine root is sensitive to the response of environmental conditions, which determines the growth and development of plants and soil nutrition status. Fine root also has an indicator effect on the environmental changes, and can reflect the health status of grassland ecosystem. As the intermediary connecting the aboveground and underground parts of vegetation, fine root plays an important role in the matter exchange and energy transfer between plants and soil, helps plants sequestrate carbon and provide for nutrient and water uptake into plants. Fine root decomposition and turnover contribute significantly to element cycling in grassland ecosystems. In karst area, fine root dynamics are controlled by the complex interaction of environmental and biotic factors. In order to explore the contribution of fine root to soil nutrients in three grasslands with different degrees of rocky desertification, the sequential soil coring and root bag methods were used to study the fine root biomass, dynamic of decomposition and release of nutrient and their responses to rocky desertification in the potential, medium and severe rocky desertification grasslands from March 2017 to January 2018. The results showed that the fine root biomass increased first and then decreased with the seasons in the three types of grasslands with different degrees of rocky desertification, while decreased with the intensification of rocky desertification. The fine root biomass was 3355.65 g/m², 2944.02 g/m² and 1806.80 g/m² in the potential, medium and severe rocky desertification grasslands. The decomposition rate of fine root showed the fast-slow trend, and the residual rate of dry matter was all less than 50% after 300 days. The releasing process of fine root organic carbon, nitrogen, phosphorus and potassium was significantly different, and the pattern of releasing was release finally. The annual return amount of fine root organic carbon, total nitrogen, total phosphorus and total potassium was 32.46-161.08 g/m², 0.24-3.88 g/m², 0.08-0.32 g/m² and 0.15-2.78 g/m², respectively. With the intensification of rocky desertification, fine root biomass and fine root decomposition rate showed a gradually decreasing trend, while the releasing of soil organic carbon and total nitrogen showed a gradually increasing trend. Therefore, knowledge of fine root dynamics and nutrient release across a broad karst area with the ability to examine the feedbacks occurring between fine root and rocky desertification is critical to our understanding of the nutrient cycle and for protecting degraded grassland and restoring vegetation.