Precipitation increases the abundance of some groups of root-associated fungal endophytes in a semiarid grassland

Abstract

Abstract. Diverse communities of Root-Associated Fungal (RAF) species, including Dark Septate Endophytes (DSE), inhabit grasses in semiarid soils. These aridlands are often distinguished by large but variable precipitation events (monsoons). We sought to compare the composition and fungal load of the RAF community inhabiting the roots of Sporobolus cryptandrus, a dominant forage grass, exposed to variable precipitation events. We used a rainfall manipulation experiment at the Sevilleta National Wildlife Refuge (SNWR) to examine the abundance and composition of the RAF communities using molecular and microscopic techniques. Molecular data reveals that the RAF communities are dominated by Ascomycetes and few sequences were related to Arbuscular Mycorrhizal Fungi (AMF). The most dominant group (Paraphaeosphaeria spp.) clearly increased in abundance in response to water amendments and the addition of similar volumes of water appeared to increase similarity among the RAF communities, irrespective of size and distribution of precipitation events. Microscopic examinations of the roots also revealed an increased fungal load when exposed to elevated moisture, irrespective of rainfall frequency. We suggest that the increase in these cosmopolitan and abundant groups of Ascomycete fungi, in part, represents a common but complicated strategy of water translocation in a variety of soil types, similar to that proposed and shown in the arbuscular mycorrhizal fungi (AMF). Additional work should examine whether many (or most) members of the Ascomycete RAF also can facultatively broker water in the larger biological network in the soil.

Precipitation variability and fire influence the temporal dynamics of soil CO2 efflux in an arid grassland

“…Our results show that a reduction in moisture stress was associated with higher temperature sensitivity, except for the year following the fire (year 2010). This is likely a result of low microbial and plant activity following the fire event (Herrera et al, 2011). Importantly, we found an overall Q 10hf of nearly 1.4 among treatments and years, which is consistent with values reported for arid grasslands (Cable et al, 2010) and the global Q 10 across different ecosystems (Bond-Lamberty & Thomson, 2010;Mahecha et al, 2010).…”

Biotic and abiotic predictors of fungal colonization in grasses of the Colorado Rockies

“…d). Edaphic conditions were also not important correlates of colonization of roots by DSE, despite their roles in prior studies (Herrera et al ., ; Newsham, ; Kivlin et al ., ). Of the four fungal groups we considered, DSE were the least likely to have predictable colonization patterns, leaving open the question of what factors influence their distributions.…”

A Multiscale, Hierarchical Model of Pulse Dynamics in Arid-Land Ecosystems

“…Experimental manipulations of fungal symbiosis in field settings can help resolve how the outcomes of plant-fungal interactions are affected by the size, frequency, and intensity of rain events. For example, the abundance of DSE in Chihuahuan Desert grassland increased in rhizosphere soils in response to increased rainfall (Herrera et al 2011). …”