Effects and mechanism of plant litter on grassland ecosystem: A review

Plant litter is dead, above and below ground; organic material i.e. leaves barks, needles, twigs and roots. Plant litter plays a key role in nutrient cycling and community organization in grassland ecosystems. Litter can have important consequences on recruitment of plant species through modification of biological, physical, and chemical features of microenvironment. Plant litter offers a major input of organic matter to the soil which modifies soil chemistry, hence impacts nutrient cycling. At early stages of litter decomposition, a particular amount of carbon is transporting to the soil nutrient pool. In terrestrial ecosystems, plant litter regulating biogeochemical cycles, maintain soil fertility, nutrient availability, and therefore influence plant growth, diversity, composition, structure, and productivity. Litter can also impact plant above net plant productivity and below net plant productivity in grassland ecosystem. Plant litter accumulation and decomposition can impact plant species composition and community structure through temperature, light and nutrient availability. The effects of plant litter on vegetation may be negative, positive or neutral due vegetation variability, study duration, habitat, latitude, quantity and quality of litter. These diverse effects of plant litter on grassland ecosystem might be due to, management practice type, management intensity, climate type, timing, precipitation and soil nutrient pool etc. Current review attempts to describe prominent effects of plant litter on vegetation, seed germination, soil fertility, Productivity, species composition, community structure and mechanism in grassland ecosystem.     

Root responses to domestication,precipitation and silicification: weeping meadow grass simplifies and alters toughness

Plant and Soil - Plant breeding usually focuses on conspicuous above-ground plant traits, yet roots fundamentally underpin plant fitness. Roots show phenotypic plasticity in response to soil...     

Effects of plant-soil feedback on tree seedling growth under arid conditions

Aims Plants are able to influence their growing environment by changing biotic and abiotic soil conditions. These soil conditions in turn can influence plant growth conditions, which is called plant–soil feedback. Plant–soil feedback is known to be operative in a wide variety of ecosystems ranging from temperate grasslands to tropical rain forests. However, little is known about how it operates in arid environments. We examined the role of plant–soil feedbacks on tree seedling growth in relation to water availability as occurring in arid ecosystems along the west coast of South America.Methods In a two-phased greenhouse experiment, we compared plant–soil feedback effects under three water levels (no water, 10% gravimetric moisture and 15% gravimetric moisture). We used sterilized soil inoculated with soil collected from northwest Peru (Prosopis pallida forests) and from two sites in north-central Chile (Prosopis chilensis forest and scrublands without P. chilensis).Important findings Plant–soil feedbacks differed between plant species and soil origins, but water availability did not influence the feedback effects. Plant–soil feedbacks differed in direction and strength in the three soil origins studied. Plant–soil feedbacks of plants grown in Peruvian forest soil were negative for leaf biomass and positive for root length. In contrast, feedbacks were neutral for plants growing in Chilean scrubland soil and positive for leaf biomass for those growing in Chilean forest soil. Our results show that under arid conditions, effects of plant–soil feedback depend upon context. Moreover, the results suggest that plant–soil feedback can influence trade-offs between root growth and leaf biomass investment and as such that feedback interactions between plants and soil biota can make plants either more tolerant or vulnerable to droughts. Based on dissecting plant–soil feedbacks into aboveground and belowground tissue responses, we conclude that plant–soil feedback can enhance plant colonization in some arid ecosystems by promoting root growth.     

Nitrate uptake and carbon exudation – do plant roots stimulate or inhibit denitrification?

Plant and Soil - Plant growth affects soil moisture, mineral N and organic C availability in soil, all of which influence denitrification. With increasing plant growth, root exudation may stimulate...     

Differential responses of soil bacteria,fungi, archaea and protists to plant species richness and plant functional group identity

Plants are known to influence belowground microbial community structure along their roots, but the impacts of plant species richness and plant functional group (FG) identity on microbial communities in the bulk soil are still not well understood. Here, we used 454‐pyrosequencing to analyse the soil microbial community composition in a long‐term biodiversity experiment at Jena, Germany. We examined responses of bacteria, fungi, archaea, and protists to plant species richness (communities varying from 1 to 60 sown species) and plant FG identity (grasses, legumes, small herbs, tall herbs) in bulk soil. We hypothesized that plant species richness and FG identity would alter microbial community composition and have a positive impact on microbial species richness. Plant species richness had a marginal positive effect on the richness of fungi, but we observed no such effect on bacteria, archaea and protists. Plant species richness also did not have a large impact on microbial community composition. Rather, abiotic soil properties partially explained the community composition of bacteria, fungi, arbuscular mycorrhizal fungi (AMF), archaea and protists. Plant FG richness did not impact microbial community composition; however, plant FG identity was more effective. Bacterial richness was highest in legume plots and lowest in small herb plots, and AMF and archaeal community composition in legume plant communities was distinct from that in communities composed of other plant FGs. We conclude that soil microbial community composition in bulk soil is influenced more by changes in plant FG composition and abiotic soil properties, than by changes in plant species richness per se.     

Variation in plant–soil interactions among temperate forest herbs

Plant Ecology - Antagonistic interactions between plants and soil biota promote species diversity in many plant communities but little is known about how these plant–soil interactions...     

Phytochemicals induced in chickpea roots selectively and non-selectively stimulate and suppress fungal endophytes and pathogens

Plant and Soil - Plant roots shape the structure of the soil microbiome by producing a wide array of phytochemicals, which in turn impact plant growth and health. The synthesis of root metabolites...     

Plant functional traits and soil carbon sequestration in contrasting biomes

Plant functional traits control a variety of terrestrial ecosystem processes, including soil carbon storage which is a key component of the global carbon cycle. Plant traits regulate net soil carbon storage by controlling carbon assimilation, its transfer and storage in belowground biomass, and its release from soil through respiration, fire and leaching. However, our mechanistic understanding of these processes is incomplete. Here, we present a mechanistic framework, based on the plant traits that drive soil carbon inputs and outputs, for understanding how alteration of vegetation composition will affect soil carbon sequestration under global changes. First, we show direct and indirect plant trait effects on soil carbon input and output through autotrophs and heterotrophs, and through modification of abiotic conditions, which need to be considered to determine the local carbon sequestration potential. Second, we explore how the composition of key plant traits and soil biota related to carbon input, release and storage prevail in different biomes across the globe, and address the biome-specific mechanisms by which plant trait composition may impact on soil carbon sequestration. We propose that a trait-based approach will help to develop strategies to preserve and promote carbon sequestration.     

Woody plant encroachment alters soil hydrological properties and reduces downward flux of water in tallgrass prairie

Plant and Soil - Plant and soil interact to shape ecosystem properties, processes and services provided. Changes in ecosystem productivity, biogeochemical cycling and plant herbivore interactions...     

Effects of fairy ring fungi on plants and soil in the alpine and temperate grasslands of China

Plant and Soil - Soil fungi are considered to be key regulators of plant and soil relationships. The fairy rings (FRs) caused by basidiomycete fungi can influence plant productivity and soil...     

Nutrient addition affects AM fungal performance and expression of plant/fungal feedback in three serpentine grasses

Plant/soil microbial community feedback can have important consequences for species composition of both the plant and soil microbial communities, however, changes in nutrient availability may alter plant reliance on mycorrhizal fungi. In this research, we tested whether plant/soil community feedback occurs and if increased soil fertility altered the plant/soil community interactions. In two greenhouse experiments we assessed plant and AM fungal performance in response to different soils (and their microbial communities), collected from under three co-occurring plants in serpentine grasslands, and nutrient treatments. The first experiment consisted of two plant species (Andropogon gerardii, Sorghastrum nutans), their soil communities, and three nutrient treatments (control, calcium, N-P-K), while the second experiment used three plant species (first two and Schizachyrium scoparium), their soil communities collected from a different site, and two nutrient treatments (control, N-P-K). Plant/soil community feedback was observed with two of the three species and was significantly affected by nutrient enrichment. Negative Sorghastrum/soil feedback was removed with the addition of N-P-K fertilizer at both sites. Andropogon/soil feedback varied between sites and nutrient treatments, while no differential Schizachyrium growth relative to soil community was observed. Addition of N-P-K fertilizer to the nutrient poor serpentine soils increased plant biomass production and affected plant/soil community interactions. Calcium addition did not affect plant biomass, but was associated with significant increases in fungal colonization regardless of plant species or soil community. Our results indicate that nutrient enrichment affected plant/soil community feedback, which has the potential to affect plant and soil community structure.     

Isotopic estimates of new carbon inputs into litter and soils in a four-year climate change experiment with Douglas-fir

Plant and Soil - Because soil is a major reservoir of terrestrial carbon and a potential sink for atmospheric CO2, determining plant inputs to soil carbon is critical for understanding ecosystem...     

Linkage of fine and coarse litter traits to soil microbial characteristics and nitrogen mineralization across topographic positions in a temperate natural forest

Plant and Soil - Topographic positions within a natural forest can considerably influence litter traits, soil microbial characteristics, and nitrogen (N) mineralization, causing plant–soil...     

Streptomyces strains alleviate water stress and increase peppermint (Mentha piperita) yield and essential oils

Plant and Soil - Drought is the most significant factor limiting plant production in a majority of agricultural fields worldwide. PGPRs (plant growth promoting rhizobacteria) are beneficial soil...     

Factorial and ‘self vs. other’ plant soil feedback experiments produce similar predictions of plant growth in communities

Plant and Soil - In species-factorial plant–soil feedback (PSF) experiments plants are grown on replicate soils from each other potential plant in a community. Species-factorial experiments...     

Impact of soil leachate on microbial biomass and diversity affected by plant diversity

Plant and Soil - High plant diversity is usually linked with high soil microbial diversity, which is hypothesized to be attributed to a high diversity of components in the soil leachate, but...     

Recovery succession drives the convergence,and grazing versus fencing drives the divergence of plant and soil N/P stoichiometry in a semiarid steppe of Inner Mongolia

Plant and Soil - Plant–soil feedbacks (PSFs) and grazing drive community dynamics in grasslands. We examined how the intensity of grazing and PSF interact to affect plant growth and explored...     

Conspecific plant–soil feedback scales with population size in Lobelia siphilitica (Lobeliaceae)

Plant–soil interactions directly affect plant success in terms of establishment, survival, growth and reproduction. Negative plant–soil feedback on such traits may therefore reduce the density and abundance of plants of a given species at a given site. Furthermore, if conspecific feedback varies among population sites, it could help explain geographic variation in plant population size. We tested for among-site variation in conspecific plant–soil feedback in a greenhouse experiment using seeds and soils from 8 natural populations of Lobelia siphilitica hosting 30–330 plants. The first cohort of seeds was grown on soil collected from each native site, while the second cohort was grown on the soil conditioned by the first. Our goal was to distinguish site-specific effects mediated by biotic and/or abiotic soil properties from those inherent in seed sources. Cohort 1 plants grown from seeds produced in small populations performed better in terms of germination, growth, and survival compared to plants produced in large populations. Plant performance decreased substantially between cohorts, indicating strong negative feedback. Most importantly, the strength of negative feedback scaled linearly (i.e., was less negative) with increasing size of the native plant population, particularly for germination and survival, and was better explained by soil- rather than seed-source effects. Even with a small number of sites, our results suggest that the potential for negative plant–soil feedback varies among populations of L. siphilitica, and that small populations were more susceptible to negative feedback. Conspecific plant–soil feedback may contribute to plant population size variation within a species’ native range.     

松嫩盐碱草地西部的植物群落特征与土壤因子动态关系分析

应用逐步回归法,分析了5~9月松嫩盐碱草地植物群落的生物量、丰富度、多样性和均匀度与同月土壤因子间的关系。松嫩盐碱草地植物群落特征受若干土壤因子的共同影响,不同月份影响因子的变化较复杂。5~7月土壤盐分和养分共同影响着松嫩盐碱草地植物群落生物量,但是土壤盐分因子与群落生物量的相关性更明显（5月的Ca²⁺质量分数,6月和7月的Mg²⁺质量分数）。土壤盐分因子在整个生长季内对松嫩盐碱草地植物群落生物量的直接作用都大于土壤养分因子的。6月时影响松嫩盐碱草地植物群落丰富度、Simpson指数和Shannon指数的土壤养分因子增加,其中土壤全氮质量分数的直接作用是所有土壤因子中最大的。8月植物群落生物量、Simpson指数和Shannon指数仅受土壤盐分因子影响,其中生物量与土壤pH值以及Simpson指数与土壤碱化度都是极显著负相关,Shannon指数与土壤含盐量显著负相关。6~9月的松嫩盐碱草地植物群落均匀度也同时受土壤养分和盐分因子的作用,其中6月和9月时土壤盐分因子对群落均匀度的直接作用更突出。生长末期（9月）松嫩盐碱草地植物群落生物量与土壤因子间的关系以及生长初期（5月）植物群落均匀度与土壤因子间的关系都不明显。     

Resistance of soil biota and plant growth to disturbance increases with plant diversity

Plant diversity is critical to the functioning of ecosystems, potentially mediated in part by interactions with soil biota. Here, we characterised multiple groups of soil biota across a plant diversity gradient in a long‐term experiment. We then subjected soil samples taken along this gradient to drought, freezing and a mechanical disturbance to test how plant diversity affects the responses of soil biota and growth of a focal plant to these disturbances. High plant diversity resulted in soils that were dominated by fungi and associated soil biota, including increased arbuscular mycorrhizal fungi and reduced plant‐feeding nematodes. Disturbance effects on the soil biota were reduced when plant diversity was high, resulting in higher growth of the focal plant in all but the frozen soils. These results highlight the importance of plant diversity for soil communities and their resistance to disturbance, with potential feedback effects on plant productivity.