James D. Ford | Geology Reports

USGS2019

Effect of permafrost thaw on plant and soil fungal community in the boreal forest: Does fungal community change mediate plant productivity response?

Permafrost thaw is leading to rapid shifts in boreal ecosystem function. Permafrost thaw affects soil carbon turnover through changes in soil hydrology, however, the biotic mechanisms regulating plant community response remain elusive. Here, we measured the response of fungal community composition and soil nutrient content in an intact permafrost plateau forest soil and an adjacent thermokarst bog using barcoded amplicon targeting ITS2 and 28S rRNA genes. Next, we used the soils from the permafrost plateau and the thermokarst bog as soil inoculum in a greenhouse experiment to measure whether shifts in fungal community and soil water level regulate plant productivity. Overall, we found that fungal community composition differed significantly between the thawed and intact permafrost sites, but soil nutrient content did not. Relative abundance of mycorrhizal fungal taxa decreased while relative abundance of putative fungal pathogens increased with permafrost thaw. In the greenhouse, we found that ecto- and arbuscular associated host plants had higher productivity in permafrost-intact soils relative to thawed soils. However, productivity of non-mycorrhizal tussock grass was more affected by soil water levels than soil communities. Our results suggest that fungal communities are crucial in mediating plant response to permafrost thaws inducing hydrology changes.

Alaska↗

USGS2017

Grand challenges in understanding the interplay of climate and land changes

Half of Earth’s land surface has been altered by human activities, creating various consequences on the climate and weather systems at local to global scales, which in turn affect a myriad of land surface processes and the adaptation behaviors. This study reviews the status and major knowledge gaps in the interactions of land and atmospheric changes and present 11 grand challenge areas for the scientific research and adaptation community in the coming decade. These land-cover and land-use change (LCLUC)-related areas include 1) impacts on weather and climate, 2) carbon and other biogeochemical cycles, 3) biospheric emissions, 4) the water cycle, 5) agriculture, 6) urbanization, 7) acclimation of biogeochemical processes to climate change, 8) plant migration, 9) land-use projections, 10) model and data uncertainties, and, finally, 11) adaptation strategies. Numerous studies have demonstrated the effects of LCLUC on local to global climate and weather systems, but these putative effects vary greatly in magnitude and even sign across space, time, and scale and thus remain highly uncertain. At the same time, many challenges exist toward improved understanding of the consequences of atmospheric and climate change on land process dynamics and services. Future effort must improve the understanding of the scale-dependent, multifaceted perturbations and feedbacks between land and climate changes in both reality and models. To this end, one critical cross-disciplinary need is to systematically quantify and better understand measurement and model uncertainties. Finally, LCLUC mitigation and adaptation assessments must be strengthened to identify implementation barriers, evaluate and prioritize opportunities, and examine how decision-making processes work in specific contexts.

Earth Interactions↗