Response of Mycorrhizal Diversity to Current Climatic Changes

Abstract

Form and function of mycorrhizas as well as tracing the presence of the mycorrhizal fungi through the geological time scale are herein first addressed. Then mycorrhizas and plant fitness, succession, mycorrhizas and ecosystem function, and mycorrhizal resiliency are introduced. From this, four hypotheses are drawn: (1) mycorrhizal diversity evolved in response to changes in Global Climate Change (GCC) environmental drivers, (2) mycorrhizal diversity will be modified by present changes in GCC environmental drivers, (3) mycorrhizal changes in response to ecological drivers of GCC will in turn modify plant, community, and ecosystem responses to the same, and (4) Mycorrhizas will continue to evolve in response to present and future changes in GCC factors. The drivers of climate change examined here are: CO2 enrichment, temperature rise, altered precipitation, increased N-deposition, habitat fragmentation, and biotic invasion increase. These impact the soil-rhizosphere, plant and fungal physiology and/or ecosystem(s) directly and indirectly. Direct effects include changes in resource availability and change in distribution of mycorrhizas. Indirect effects include changes in below ground allocation of C to roots and changes in plant species distribution. GCC ecological drivers have been partitioned into four putative time frames: (1) Immediate (1–2 years) impacts, associated with ecosystem fragmentation and habitat loss realized through loss of plant-hosts and disturbance of the soil; (2) Short-term (3–10 year) impacts, resultant of biotic invasions of exotic mycorrhizal fungi, plants and pests, diseases and other abiotic perturbations; (3) Intermediate-term (11–20 year) impacts, of cumulative and additive effects of increased N (and S) deposition, soil acidification and other pollutants; and (4) Long-term (21–50+ year) impacts, where increased temperatures and CO2 will destabilize global rainfall patterns, soil properties and plant ecosystem resilience. Due to dependence on their host for C-supply, orchid mycorrhizas and all heterotrophic mycorrhizal groups will be immediately impacted through loss of habitat and plant-hosts. Ectomycorrhizal (ECM) associations will be the principal group subject to short-term impacts, along with Ericoid mycorrhizas occurring in high altitude or high latitude ecosystems. This is due to susceptibility (low buffer capacity of soils) of many of the ECM systems and that GCC is accentuated at high latitudes and altitudes. Vulnerable mycorrhizal types subject to intermediate-term GCC changes include highly specialized ECM species associated with forest ecosystems and finally arbuscular mycorrhizas (AM) associated with grassland ecosystems. Although the soils of grasslands are generally well buffered, the soils of arid lands are highly buffered and will resist even fairly long term GCC impacts, and thus these arid, largely AM systems will be the least affect by GCC. Once there are major perturbations to the global hydrological cycle that change rainfall patterns and seasonal distributions, no...

Plant genetic effects on soils under climate change

“…Error bars represent ± one standard error plant water use). Reduced plant water-use might result in higher soil moisture (in this hypothetical example) and thus increase bacterial communities (Schimel et al 2007), but have unknown effects on mycorrhizal communities (Bellgard and Williams 2011). This would have unpredictable impacts on carbon sequestration, but probably increase organic matter decomposition, soil nutrient availability, and reduce ecosystem transpiration.…”

“…Finally, d multivariate leaf physiological (economic) traits represented by a principle components analysis axis score vary predictably with degree of climate change in intraspecific assisted migration experiments with the species P. fremontii (after Grady et al 2013). Such multivariate trait differences may have proportional, and sometimes re-enforcing effects on soil communities and soil function generalized potential responses of plant traits to specific climate change factors based on either reviews (Horton and Hart 1998;Bellgard and Williams 2011;Churma et al 2011;Norby and Zak 2011;Bardgett et al 2013;Keenan et al 2013) or inferred general understanding of plant responses to temperature, soil moisture, and increased CO 2 (assuming that the basic physiological responses to these factors also represent traits favored by directional selection). These responses are provided here not as a set of predictions, but rather for the heuristic purpose of visualizing how multiple plant traits interact and affect ecosystem function and communities in a climate change framework.…”

“…After three generations, the rapid responses of soil communities to altered conditions enhanced plant fitness when both conditioned and naïve plants were grown with the microbial community that best matched the environmental conditions (i.e., drought adapted soil communities led to enhanced plant fitness under drought conditions). Moreover, mycorrhizal fungi are known to convey plant resistance to extreme events potentially increasing plant genotype persistence under a changing climate (Bellgard and Williams 2011;Hoeksema and Classen 2012). For example, mycorrhizal fungi can convey plant tolerance to drought, and thus drought resistant genotypemycorrhizal pairs are likely to persist as drought-prone ecosystems dry under climatic change (e.g.…”

Demographic responses of boreal-montane orchid Malaxis monophyllos (L.) Sw. populations to contrasting environmental conditions

“…The model group of plants which, because of strong connections with other components of their habitats play a vital role in sensitivity to global and local changes and provide a warning of impending damages (acting as bioindicators), are orchids [31][32][33]. They very often exhibit fast responses to environmental changes, which is reflected mainly in decreases in abundances of local populations, as well in lowering their reproductive potential (e.g., [34][35][36][37]), which makes most orchid species relatively highly threatened.…”

Seedling mycorrhizal type and soil chemistry are related to canopy condition of Eucalyptus gomphocephala

“…Reduction in tree vigor might impact on mycorrhizal fungi either directly through changes in resource availability and distribution of mycorrhizas or indirectly through changes in carbon allocation to roots and changes in plant species distribution (Bellgard and Williams 2011). Swaty et al (2004) suggested that changes in mycorrhizal colonization might be related to the stress level of the host plant.…”