MycoDB, a global database of plant response to mycorrhizal fungi

Plants form belowground associations with mycorrhizal fungi in one of the most common symbioses on Earth. However, few large-scale generalizations exist for the structure and function of mycorrhizal symbioses, as the nature of this relationship varies from mutualistic to parasitic and is largely context-dependent. We announce the public release of MycoDB, a database of 4,010 studies (from 438 unique publications) to aid in multi-factor meta-analyses elucidating the ecological and evolutionary context in which mycorrhizal fungi alter plant productivity. Over 10 years with nearly 80 collaborators, we compiled data on the response of plant biomass to mycorrhizal fungal inoculation, including meta-analysis metrics and 24 additional explanatory variables that describe the biotic and abiotic context of each study. We also include phylogenetic trees for all plants and fungi in the database. To our knowledge, MycoDB is the largest ecological meta-analysis database. We aim to share these data to highlight significant gaps in mycorrhizal research and encourage synthesis to explore the ecological and evolutionary generalities that govern mycorrhizal functioning in ecosystems

The pervasive and multifaceted influence of biocrusts on water in the world's drylands

The capture and use of water are critically important in drylands, which collectively constitute Earth's largest biome. Drylands will likely experience lower and more unreliable rainfall as climatic conditions change over the next century. Dryland soils support a rich community of microphytic organisms (biocrusts), which are critically important because they regulate the delivery and retention of water. Yet despite their hydrological significance, a global synthesis of their effects on hydrology is lacking. We synthesized 2,997 observations from 109 publications to explore how biocrusts affected five hydrological processes (times to ponding and runoff, early [sorptivity] and final [infiltration] stages of water flow into soil, and the rate or volume of runoff) and two hydrological outcomes (moisture storage, sediment production). We found that increasing biocrust cover reduced the time for water to pond on the surface (−40%) and commence runoff (−33%), and reduced infiltration (−34%) and sediment production (−68%). Greater biocrust cover had no significant effect on sorptivity or runoff rate/amount, but increased moisture storage (+14%). Infiltration declined most (−56%) at fine scales, and moisture storage was greatest (+36%) at large scales. Effects of biocrust type (cyanobacteria, lichen, moss, mixed), soil texture (sand, loam, clay), and climatic zone (arid, semiarid, dry subhumid) were nuanced. Our synthesis provides novel insights into the magnitude, processes, and contexts of biocrust effects in drylands. This information is critical to improve our capacity to manage dwindling dryland water supplies as Earth becomes hotter and drier.This work was conducted as part of the Powell Working Group “Completing the dryland puzzle: creating a predictive framework for biological soil crust function and response to climate change” supported by the John Wesley Powell Center for Analysis and Synthesis, funded by the US Geological Survey. J.B. and S.R. were funded by USGS Ecosystems and Land Use Change Mission Areas, by the US Department of Energy (DESC-0008168), and by the Strategic Environmental Research and Development Program (RC18-1322). J.D. is supported by grants from the Holsworth Wildlife Research Endowment & The Ecological Society of Australia, and a scholarship from China Scholarship Council (No. 201706040073). B.C. is supported by grants from the National Science Foundation (award DEB-1844531) and DePaul University. M.A.B. is supported by a grant from the National Science Foundation (award DEB-1638966). B.W. was supported by the Max Planck Society and a Paul Crutzen Nobel Laureate Fellowship. E.H.-S. was supported by CONACYT grant 251388 B. F.T.M. was supported by the European Research Council (ERC grant agreement 647038 [BIODESERT]) and Generalitat Valenciana (CIDEGENT/2018/041)

Impact of changing climate on bryophyte contributions to terrestrial water, carbon, and nitrogen cycles

Bryophytes, including the lineages of mosses, liverworts, and hornworts, are the second-largest photoautotroph group on Earth. Recent work across terrestrial ecosystems has highlighted how bryophytes retain and control water, fix substantial amounts of carbon (C), and contribute to nitrogen (N) cycles in forests (boreal, temperate, and tropical), tundra, peatlands, grasslands, and deserts. Understanding how changing climate affects bryophyte contributions to global cycles in different ecosystems is of primary importance. However, because of their small physical size, bryophytes have been largely ignored in research on water, C, and N cycles at global scales. Here, we review the literature on how bryophytes influence global biogeochemical cycles, and we highlight that while some aspects of global change represent critical tipping points for survival, bryophytes may also buffer many ecosystems from change due to their capacity for water, C, and N uptake and storage. However, as the thresholds of resistance of bryophytes to temperature and precipitation regime changes are mostly unknown, it is challenging to predict how long this buffering capacity will remain functional. Furthermore, as ecosystems shift their global distribution in response to changing climate, the size of different bryophyte-influenced biomes will change, resulting in shifts in the magnitude of bryophyte impacts on global ecosystem functions

原著

Mean Plant Response to Mycorrhizal Inoculation (PDF 113 kb

Greenhouse monitoring data

Cover through time of added biocrust species in three greenhouse experiments. File also includes derived data such as overyield and productivity as defined in text

Seven years of carbon dioxide enrichment, nitrogen fertilization and plant diversity influence arbuscular mycorrhizal fungi in a grassland ecosystem

We tested the prediction that the abundance and diversity of arbuscular mycorrhizal (AM) fungi are influenced by resource availability and plant community composition by examining the joint effects of carbon dioxide (CO2) enrichment, nitrogen (N) fertilization and plant diversity on AM fungi. We quantified AM fungal spores and extramatrical hyphae in 176 plots after 7 yr of treatment with all combinations of ambient or elevated CO2 (368 or 560 ppm), with or without N fertilization (0 or 4 g N m−2), and one (monoculture) or 16 host plant species (polyculture) in the BioCON field experiment at Cedar Creek Ecosystem Science Reserve, Minnesota, USA. Extramatrical hyphal lengths were increased by CO2 enrichment, whereas AM spore abundance decreased with N fertilization. Spore abundance, morphotype richness and extramatrical hyphal lengths were all greater in monoculture plots. A structural equation model showed AM fungal biovolume was most influenced by CO2 enrichment, plant community composition and plant richness, whereas spore richness was most influenced by fungal biovolume, plant community composition and plant richness. Arbuscular mycorrhizal fungi responded to differences in host community and resource availability, suggesting that mycorrhizal functions, such as carbon sequestration and soil stability, will be affected by global change

Heavy Logging Machinery Impacts Soil Physical Properties More than Nematode Communities

Mechanized logging equipment causes considerable soil disturbance, but little information is available regarding thresholds for impacts on soil nematodes—critical members of soil foodwebs which perform important ecological functions. We examined responses of nematode communities and soil physical characteristics to the increasing number of passes (one, three, or nine) by a tracked feller buncher during thinning of a xeric mixed conifer forest in New Mexico, USA. Within and between the harvester tracks, we measured soil surface penetration resistance and shear strength, quantified bulk density at four depth increments up to a maximum depth of 27 cm, and characterized nematode assemblages in the upper 10 cm. Eight months after treatment, nematode communities were less impacted than soil physical properties by harvester passes. Total nematode abundance was unaffected by any level of feller buncher disturbance, and sensitive K-selected nematode groups were reduced only at nine passes. Conversely, soil compaction occurred with a single pass and extended deep into the soil profile to at least 23–27 cm. The first pass also decreased surface penetration resistance and shear strength, indicating disruption of soil surface structural integrity. Additional passes did not further increase bulk density or decrease surface structural integrity. Our results indicate that low levels of logging machinery traffic may have negligible effects on nematode communities, but nevertheless emphasize the importance of minimizing areas subjected to disturbance because of impacts on soil physical properties