02613nas a2200217 4500008004100000022001400041245009900055210007100154300001200225490000800237520196300245100001602208700001302224700001702237700001902254700001802273700001502291700001402306700001302320856006202333 2020 eng d a0030-129900aPlant–microbial interactions facilitate grassland species coexistence at the community level0 aPlant–microbial interactions facilitate grassland species coexis a533-5430 v1293 a

Interspecific competition and plant–soil feedbacks are powerful drivers of plant community structure. However, across a range of edaphic conditions the interactive effects of these drivers on complex plant communities remain unclear. For example, plant–soil feedback studies focus on soil trained by a single plant species. We developed a method to assess effects of plant–microbial interactions (PMI) on a complex plant community. We established mesocosms with 13 grassland species, grown individually or together, in overgrazed or restored soil, with or without soil microbial inoculum collected from a productive and diverse native grassland. We assessed biomass production as influenced by edaphic conditions, interspecific competition and PMI. Furthermore, we assessed potential influences of interspecific competition and edaphic conditions on strength and direction of PMI. Our results indicate PMI drives negative growth responses for graminoids while forbs experience positive growth responses. Generally, interspecific competition did not alter the magnitude or direction of PMI‐mediated growth responses. Edaphic conditions altered the influence of soil microbial communities on individual plant growth while PMI facilitated plant evenness. In plant community mesocosms, PMI‐associated benefits were observed in overgrazed soil. However, interspecific competition overwhelmed plant growth benefits associated with soil microbial communities when plant communities were grown in restored soil. In mesocosms containing dominant grass species, interspecific competition had negative effects on species coexistence, but both positive and negative PMI partially counterbalanced this influence on plant species evenness. Understanding these mechanisms may improve our capacity to manage diverse and productive grasslands by enabling prediction of plant community composition following disturbance and subsequent restoration.

1 aLi, Jiahuan1 aXie, Shu1 aWilson, G.T.1 aCobb, Adam, B.1 aTang, Shiming1 aGuo, Lizhu1 aWang, Kun1 aDeng, Bo uhttps://onlinelibrary.wiley.com/doi/abs/10.1111/oik.0660900671nas a2200205 4500008004100000245012800041210006900169300001400238490000800252100001800260700001800278700001700296700001700313700001900330700001300349700001500362700001300377700001900390856005600409 2019 eng d00aFollowing legume establishment, microbial and chemical associations facilitate improved productivity in degraded grasslands0 aFollowing legume establishment microbial and chemical associatio a273 - 2920 v4431 aZhou, Jiqiong1 aZhang, Fengge1 aHuo, Yunqian1 aWilson, G.T.1 aCobb, Adam, B.1 aXu, Xixi1 aXiong, Xue1 aLiu, Lin1 aZhang, Yingjun uhttp://link.springer.com/10.1007/s11104-019-04169-900569nas a2200157 4500008004100000245012900041210006900170300001400239490000700253100001800260700001700278700001900295700001700314700001900331856006100350 2019 eng d00aPhosphorus and mowing improve native alfalfa establishment, facilitating restoration of grassland productivity and diversity0 aPhosphorus and mowing improve native alfalfa establishment facil a647 - 6570 v301 aZhou, Jiqiong1 aWilson, G.T.1 aCobb, Adam, B.1 aYang, Gaowen1 aZhang, Yingjun uhttps://onlinelibrary.wiley.com/doi/abs/10.1002/ldr.325102282nas a2200181 4500008004100000245010700041210006900148300001600217490000700233520169500240100001401935700001401949700001301963700001701976700001901993700001902012856006902031 2018 eng d00aDefoliation and arbuscular mycorrhizal fungi shape plant communities in overgrazed semiarid grasslands0 aDefoliation and arbuscular mycorrhizal fungi shape plant communi a1847 - 18560 v993 a

Overgrazing substantially contributes to global grassland degradation by decreasing plant community productivity and diversity through trampling, defoliation, and removal of nutrients. Arbuscular mycorrhizal (AM) fungi also play a critical role in plant community diversity, composition, and primary productivity, maintaining ecosystem functions. However, interactions between grazing disturbances, such as trampling and defoliation, and AM fungi in grassland communities are not well known. We examined influences of trampling, defoliation, and AM fungi on semiarid grassland plant community composition for 3 yr, by comparing all combinations of these factors. Benomyl fungicide was applied to reduce AM fungal abundance. Overgrazing typically resulted in reduced dominance of Stipa Krylovii, contributing to degradation of typical steppe grasslands. Our results indicated trampling generally had little effect on plant community composition, unless combined with defoliation or AM fungal suppression. Defoliation was the main component of grazing that promoted dominance of Potentilla acaulis over Stipa krylovii and Artemisia frigida, presumably by alleviating light limitation. In non‐defoliated plots, AM fungi promoted A. frigida, with a concomitant reduction in S. krylovii growth compared to corresponding AM suppressed plots. Our results indicate AM fungi and defoliation jointly suppress S. krylovii biomass; however, prolonged defoliation weakens mycorrhizal influence on plant community composition. These findings give new insight into dominant plant species shifts in degraded semiarid grasslands.

1 aYang, Xin1 aShen, Yue1 aLiu, Nan1 aWilson, G.T.1 aCobb, Adam, B.1 aZhang, Yingjun uhttps://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecy.240102146nas a2200217 4500008004100000245012800041210006900169300001400238490000700252520144500259100001601704700001701720700001701737700001901754700002801773700001701801700001901818700001901837700001701856856005501873 2018 eng d00aLong-term effects of grazing and topography on extra-radical hyphae of arbuscular mycorrhizal fungi in semi-arid grasslands0 aLongterm effects of grazing and topography on extraradical hypha a117 - 1270 v283 a

Grazing and topography have drastic effects on plant communities and soil properties. These effects are thought to influence arbuscular mycorrhizal (AM) fungi. However, the simultaneous impacts of grazing pressure (sheep ha-1) and topography on plant and soil factors and their relationship to the production of extra-radical AM hyphae are not well understood. Our 10-year study assessed relationships between grazing, plant species richness, aboveground plant productivity, soil nutrients, edaphic properties, and AM hyphal length density (HLD) in different topographic areas (flat or sloped). We found HLD linearly declined with increasing grazing pressure (1.5-9.0 sheep ha-1) in sloped areas, but HLD was greatest at moderate grazing pressure (4.5 sheep ha-1) in flat areas. Structural equation modeling indicates grazing reduces HLD by altering soil nutrient dynamics in sloped areas, but non-linearly influences HLD through plant community and edaphic changes in flat areas. Our findings highlight how topography influences key plant and soil factors, thus regulating the effects of grazing pressure on extra-radical hyphal production of AM fungi in grasslands. Understanding how grazing and topography influence AM fungi in semi-arid grasslands is vital, as globally, severe human population pressure and increasing demand for food aggravate the grazing intensity in grasslands.

1 aRen, Haiyan1 aGui, Weiyang1 aBai, Yongfei1 aStein, Claudia1 aRodrigues, Jorge, L. M.1 aWilson, G.T.1 aCobb, Adam, B.1 aZhang, Yingjun1 aYang, Gaowen uhttp://link.springer.com/10.1007/s00572-017-0812-x02177nas a2200241 4500008004100000245014500041210006900186300001200255490000800267520142800275100001701703700001601720700001301736700001901749700001901768700001701787700001401804700001301818700001401831700001801845700001701863856005501880 2018 eng d00aPlant functional group influences arbuscular mycorrhizal fungal abundance and hyphal contribution to soil CO2 efflux in temperate grasslands0 aPlant functional group influences arbuscular mycorrhizal fungal  a157-1700 v4323 a

Background and aims: Arbuscular mycorrhizal (AM) fungi are abundant in grassland ecosystem. We assessed AM hyphal contributions to soil CO2 efflux across plant functional groups to better quantify AM fungal influences on soil carbon dynamics.


Methods: We conducted a field experiment using in-growth mesocosms to partition soil CO2 efflux from roots, AM hyphae, and free-living soil microbes associated with C3 grasses, C4 grasses, forbs, and diverse plant communities from May to August in 2017.


Results: AM hyphae contributed <10% to total soil respiration in forb communities and diverse plant communities but accounted for as much as 32% in C3 grasses. Plant functional groups differed in hyphal production efficiencies (the ratio of AM hyphal length to aboveground biomass), with the lowest in C3 grasses (0.47?±?0.15 m g-1) and the greatest in forbs (3.27?±?0.55 m g-1). Mowing reduced hyphal production efficiency of C4 grasses and forbs but did not affect total soil respiration. AM hyphal and microbial respiration peaked at the middle of the growing season, however there was no significant seasonal variation in root respiration.


Conclusion: AM hyphal respiration is an important pathway of carbon flux from plants to atmosphere. Shifts in plant community composition can influence soil carbon processes by regulating hyphal production and respiration.

1 aGui, Weiyang1 aRen, Haiyan1 aLiu, Nan1 aZhang, Yingjun1 aCobb, Adam, B.1 aWilson, G.T.1 aSun, Xiao1 aHu, Jian1 aXiao, Yan1 aZhang, Fengge1 aYang, Gaowen uhttp://link.springer.com/10.1007/s11104-018-3789-002922nas a2200205 4500008004100000245012500041210006900166300000800235490000600243520225200249100001802501700001702519700001902536700001702555700001802572700001702590700001702607700001902624856007302643 2018 eng d00aTrichoderma biofertilizer links to altered soil chemistry, altered microbial communities, and improved grassland biomass0 aTrichoderma biofertilizer links to altered soil chemistry altere a8480 v93 a

In grasslands, forage and livestock production results in soil nutrient deficits as grasslands typically receive no nutrient inputs, leading to a loss of grassland biomass. The application of mature compost has been shown to effectively increase grassland nutrient availability. However, research on fertilization regime influence and potential microbial ecological regulation mechanisms are rarely conducted in grassland soil. We conducted a two-year experiment in meadow steppe grasslands, focusing on above- and belowground consequences of organic or Trichoderma biofertilizer applications and potential soil microbial ecological mechanisms underlying soil chemistry and microbial community responses. Grassland biomass significantly (p = 0.019) increased following amendment with 9,000 kg ha−1 of Trichoderma biofertilizer (composted cattle manure + inoculum) compared with other assessed organic or biofertilizer rates, except for BOF3000 (fertilized with 3,000 kg ha−1 biofertilizer). This rate of Trichoderma biofertilizer treatment increased soil antifungal compounds that may suppress pathogenic fungi, potentially partially responsible for improved grassland biomass. Nonmetric multidimensional scaling (NMDS) revealed soil chemistry and fungal communities were all separated by different fertilization regime. Trichoderma biofertilizer (9,000 kg ha−1) increased relative abundances of Archaeorhizomyces and Trichoderma while decreasing Ophiosphaerella. Trichoderma can improve grassland biomass, while Ophiosphaerella has the opposite effect as it may secrete metabolites causing grass necrosis. Correlations between soil properties and microbial genera showed plant-available phosphorus may influence grassland biomass by increasing Archaeorhizomyces and Trichoderma while reducing Ophiosphaerella. According to our structural equation modeling (SEM), Trichoderma abundance was the primary contributor to aboveground grassland biomass. Our results suggest Trichoderma biofertilizer could be an important tool for management of soils and ultimately grassland plant biomass.

1 aZhang, Fengge1 aHuo, Yunqian1 aCobb, Adam, B.1 aLuo, Gongwen1 aZhou, Jiqiong1 aYang, Gaowen1 aWilson, G.T.1 aZhang, Yingjun uhttp://journal.frontiersin.org/article/10.3389/fmicb.2018.00848/full03815nas a2200181 4500008004100000245011600041210006900157300001200226490000700238520321600245100001803461700001903479700001703498700001903515700001503534700001703549856006703566 2017 eng d00aSmall vegetation gaps increase reseeded yellow-flowered alfalfa performance and production in native grasslands0 aSmall vegetation gaps increase reseeded yellowflowered alfalfa p a41 - 520 v243 a

Reseeding yellow-flowered alfalfa (YFA) in degraded grasslands may require a vegetation-free microsite for germination and subsequent establishment. This study aimed to examine the role of microclimates of different-sized vegetation gaps on seedling performance and adult plant production of YFA. Field microsites were established in the meadow steppe of Hulunber, Inner Mongolia, China. Seedling performance, plant production, the microclimate within vegetation gaps, and soil nutrients (plant-available N, P, and K, total N concentration) were assessed at the end of each growing season from 2013 to 2015. Our results indicate light availability, and topsoil temperature of each gap were significantly increased as gap size increased, while topsoil moisture and air relative moisture were decreased in larger gaps. Small gaps (diameter ≤10 cm) improved seedling emergence, survival, biomass, and root nodulation, as compared with seedling performance associated with the larger gaps, presumably in response to increased shade and moisture. Additionally, large gaps (>20 or >40 cm) were characterized by significantly lower plant-available P, total N concentrations, plant-available K, and soil pH. However, root exclusion treatments did not improve overall seedling performance, plant production, or soil properties, as compared to corresponding microsites with root presence, regardless of gap size. Our results suggest that reseeding YFA into grasslands where disturbance, such as light grazing, has resulted in small gaps will be more effective than in highly degraded grasslands.

1 aZhou, Jiqiong1 aZhang, Yingjun1 aWilson, G.T.1 aCobb, Adam, B.1 aLu, Wenjie1 aGuo, Yanping uhttps://linkinghub.elsevier.com/retrieve/pii/S1439179117300464