Background: Large-diameter trees have an outsized influence on aboveground forest dynamics, composition, and structure. Although their influence on aboveground processes is well studied, their role in shaping belowgro...Background: Large-diameter trees have an outsized influence on aboveground forest dynamics, composition, and structure. Although their influence on aboveground processes is well studied, their role in shaping belowground fungal communities is largely unknown. We sought to test if (i) fungal community spatial structure matched aboveground forest structure;(ii) fungal functional guilds exhibited differential associations to aboveground trees, snags, and deadwood;and (iii) that large-diameter trees and snags have a larger influence on fungal community richness than smaller-diameter trees. We used MiSeq sequencing of fungal communities collected from soils in a spatially intensive survey in a portion of Cedar Breaks National Monument, Utah, USA. We used random forest models to explore the spatial structure of fungal communities as they relate to explicitly mapped trees and deadwood distributed across 1.15 ha of a 15.32-ha mapped subalpine forest. Results: We found 6,177 fungal amplicon sequence variants across 117 sequenced samples. Tree diameter, dead-wood presence, and tree species identity explained more than twice as much variation (38.7% vs. 10.4%) for ectomy-corrhizal composition and diversity than for the total or saprotrophic fungal communities. Species identity and dis-tance to the nearest large-diameter tree (≥ 40.2 cm) were better predictors of fungal richness than were the identity and distance to the nearest tree. Soil nutrients, topography, and tree species differentially influenced the composition and diversity of each fungal guild. Locally rare tree species had an outsized influence on fungal community richness. Conclusions: These results highlight that fungal guilds are differentially associated with the location, size, and species of aboveground trees. Large-diameter trees are implicated as drivers of belowground fungal diversity, particularly for ectomycorrhizal fungi.展开更多
Increases in climate variability, including extremes, may be expected with anthropogenic climate change, but some evidence is contrary. The issue is important because the consequences of variability can be critical fo...Increases in climate variability, including extremes, may be expected with anthropogenic climate change, but some evidence is contrary. The issue is important because the consequences of variability can be critical for ecosystems. It has long been known and often rehearsed that ecological consequences of increased variability may be greater than those that result from expected changes in mean temperature and precipitation. Tree rings have been useful indicators of ecological response to climate change and used as proxies for climate variability;work in the Rocky Mountains, USA, has been particularly informative. Chronologies from two high elevation species ranging over 2500 km were analyzed for changes in variance through time. These spatially extensive and disaggregated tree ring records do not show a consistent pattern of change in variance over the past 500 or 100 years; heteroscedasticity has recently been greater. A lack of consistent response in growth over a period encompassing changes in mean climate indicates that mountain environments, with inconsistent trends in temperature and precipitation,may be too complex to act as sentinels.展开更多
基金Funding was received from the Natural Science and Engineering Council of Canada to JK and the Utah Agricultural Experiment Station(Projects 1153,1398 and 1423 to JAL)which has designated this as Journal Paper 9626.
文摘Background: Large-diameter trees have an outsized influence on aboveground forest dynamics, composition, and structure. Although their influence on aboveground processes is well studied, their role in shaping belowground fungal communities is largely unknown. We sought to test if (i) fungal community spatial structure matched aboveground forest structure;(ii) fungal functional guilds exhibited differential associations to aboveground trees, snags, and deadwood;and (iii) that large-diameter trees and snags have a larger influence on fungal community richness than smaller-diameter trees. We used MiSeq sequencing of fungal communities collected from soils in a spatially intensive survey in a portion of Cedar Breaks National Monument, Utah, USA. We used random forest models to explore the spatial structure of fungal communities as they relate to explicitly mapped trees and deadwood distributed across 1.15 ha of a 15.32-ha mapped subalpine forest. Results: We found 6,177 fungal amplicon sequence variants across 117 sequenced samples. Tree diameter, dead-wood presence, and tree species identity explained more than twice as much variation (38.7% vs. 10.4%) for ectomy-corrhizal composition and diversity than for the total or saprotrophic fungal communities. Species identity and dis-tance to the nearest large-diameter tree (≥ 40.2 cm) were better predictors of fungal richness than were the identity and distance to the nearest tree. Soil nutrients, topography, and tree species differentially influenced the composition and diversity of each fungal guild. Locally rare tree species had an outsized influence on fungal community richness. Conclusions: These results highlight that fungal guilds are differentially associated with the location, size, and species of aboveground trees. Large-diameter trees are implicated as drivers of belowground fungal diversity, particularly for ectomycorrhizal fungi.
文摘Increases in climate variability, including extremes, may be expected with anthropogenic climate change, but some evidence is contrary. The issue is important because the consequences of variability can be critical for ecosystems. It has long been known and often rehearsed that ecological consequences of increased variability may be greater than those that result from expected changes in mean temperature and precipitation. Tree rings have been useful indicators of ecological response to climate change and used as proxies for climate variability;work in the Rocky Mountains, USA, has been particularly informative. Chronologies from two high elevation species ranging over 2500 km were analyzed for changes in variance through time. These spatially extensive and disaggregated tree ring records do not show a consistent pattern of change in variance over the past 500 or 100 years; heteroscedasticity has recently been greater. A lack of consistent response in growth over a period encompassing changes in mean climate indicates that mountain environments, with inconsistent trends in temperature and precipitation,may be too complex to act as sentinels.
