Tree proximity, soil pathways and common mycorrhizal networks: their influence on the utilization of redistributed water by understory seedlings

Schoonmaker, Amanda; Teste, François P.; Simard, Suzanne W.; Guy, Robert D.

doi:10.1007/s00442-007-0852-6

Cited by 45 publications

(27 citation statements)

References 33 publications

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“…That this MN effect was not confounded by the presence of the mesh bag was confirmed by field observations of root distribution and Oecologia (2008) 158:193-203 195 root biomass data (see ''Results'') showing that seedlings grown in the no-mesh treatment had access to the same volume of soil as seedlings in mesh bags. We also found that seedlings in the no-mesh treatment took up the same amount of hydraulically redistributed water as seedlings in mesh bags (Schoonmaker et al 2007), confirming the absence of a ''bag effect''.…”

Section: Site Description and Experimental Designsupporting

confidence: 50%

“…Facilitation was likely the result of an increase in EM status (colonization, richness, and diversity) (Cline et al 2005;Teste et al, in review), MN potential (Teste 2008), greater available soil water via hydraulic redistribution (Schoonmaker et al 2007), and perhaps nutrient sharing via MNs (Selosse et al 2006). Competition resulted from the presence of mature trees and surrounding AM plants, but this varied spatially.…”

Section: Facilitation and Competition Dynamicsmentioning

confidence: 97%

“…The results suggest that mature trees were competitive for soil water and nutrients under their crowns, but beyond the dripline, access to the MN as well as declining mature root density and resource (water and nutrient) competition resulted in a net positive benefit to survival. Improved water relations may have resulted from direct water transfer through MNs, from hydraulic redistribution from trees to seedlings mediated by rhizomorphs (Duddridge et al 1980;Brownlee et al 1983) or MNs (Egerton-Warburton et al 2007;Schoonmaker et al 2007), or simply by lack of tree crown interception of rainfall. These results demonstrate that MN effects in dry forests are spatially complex, just as are the distributions of EM fungal species (Erland and Taylor 2003).…”

Section: Mn Effectsmentioning

confidence: 99%

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Mycorrhizal networks and distance from mature trees alter patterns of competition and facilitation in dry Douglas-fir forests

Teste

Simard

2008

Oecologia

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The distribution of dry Douglas-fir forests in western North America is expected to shift northward with climate change and disappear from the grassland interface in the southern interior of British Columbia. This shift may be accentuated by clearcutting, a common harvesting practice that aims to reduce the competitive effects of residual mature trees on new regeneration, but in so doing, ignores their facilitative effects. In this study, we investigated the net effects of competition from and facilitation by mature trees retained on harvested sites on seedling establishment in the dry interface Douglas-fir forests. We demonstrate that access to a mycorrhizal network (MN) and proximity to trees have important influences on seedling performance. On six sites, we established trenched plots around 24 mature Pseudotsuga menziesii var. glauca (Douglas-fir) trees, then planted Douglas-fir seedlings into four mesh treatments that served to restrict MN access (i.e., planted into mesh bags with 0.5-, 35-, or 250-microm pores, or without mesh) or into impermeable bags (grown in isolation) at four distances (0.5, 1.0, 2.5, or 5.0 m). Seedling survival tended to be greater and water stress lower where seedlings had full access to the MN. Seedling height, shoot biomass, needle biomass, and nutrient uptake peaked at 2.5-5.0 m from mature trees. Seedlings 0.5 m from mature trees had lower CO2 assimilation rates and wood delta(13)C compared to seedlings 5.0 m away. Competition for soil resources was highest near mature trees but facilitation was relatively greater at further distances, resulting in a zone of net benefit for seedlings. These results show that intraspecific tree-seedling interactions are both competitive and facilitative in dry Douglas-fir forests, and that they are spatially dependent. After disturbance, maintaining residual mature trees may be important for their beneficial regeneration zones.

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Section: Site Description and Experimental Designsupporting

confidence: 50%

Section: Facilitation and Competition Dynamicsmentioning

confidence: 97%

Section: Mn Effectsmentioning

confidence: 99%

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Mycorrhizal networks and distance from mature trees alter patterns of competition and facilitation in dry Douglas-fir forests

Teste

Simard

2008

Oecologia

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“…Colonization of seedling roots by ectomycorrhizal (EcM) fungi can provide greater access to nutrients and water (Schoonmaker et al, 2007) and promote carbon cycling (Talbot et al, 2008). Bacteria associated with EcM are known to mobilize key nutrients from minerals and organic substrates (Burke et al, 2008;Frey-Klett et al, 2007) , while many key processes, such as nitrogen fixation, can be carried out by bacteria living freely in the soil (Izquierdo and Nüsslein, 2006).…”

Section: Introductionmentioning

confidence: 99%

Impact of wildfire intensity and logging on fungal and nitrogen-cycling bacterial communities in British Columbia forest soils

Kennedy

Egger

2010

Forest Ecology and Management

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Wildfire and logging are common disturbances in the forests of northwestern North America, causing changes in soil chemistry and microbiology, including fungal and nitrogen-cycling bacterial communities. These organisms play key roles in nutrient cycling, and affect the regeneration of tree seedlings after disturbance. We studied the effects of wildfire and logging on fungal and nitrogen-cycling communities in the rhizosphere of 16 month-old Douglas-fir seedlings as they regenerated in burned and logged soils. Seeds were planted against root windows that were set up vertically in the soil, with a removable front panel used to access the seedling rhizosphere soil surface.Windows were established in control, lightly burned, and severely burned plots, as well as two types of logged plots (clearcut and screefed clearcut). Soil scrapings from the root window-soil interface were taken and the structure of fungal and nitrogen-cycling communities was resolved using length-heterogeneity PCR (LH-PCR) of fungal nuclear ribosomal RNA, and terminal restriction fragment length polymorphism (T-RFLP) analysis of nifH and nosZ genes. We found striking differences in the community structure of fungal, denitrifying, and N-fixing communities in response to burning and logging. With the exception of clearcut and screefed clearcut, which were generally similar, each treatment had a unique impact on community structure for these genes.Burning and logging also impacted the relative richness and evenness of these communities. Fungal relative richness and evenness increased in response to logging and severe burning, while denitrifier relative richness and evenness increased in all disturbance treatments, and N-fixing bacterial relative richness and evenness decreased in response to burning. The greatest differences in microbial community structure, relative 3 richness, and evenness were found in the comparisons of lightly burned and logged treatments. The results suggest that the presence of an intact forest floor influences soil microbial communities less than the presence of living trees.

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“…In similar forests nearby, we have proven this experimentally, showing that seedling establishment success increased substantially where they had full access to the network of older Douglas-fir trees (Teste and Simard 2008;Teste et al 2009b). Access to the network not only improved seedling survival and physiology, but this was associated with colonization of the seedlings by a more complex fungal community as well as carbon, nitrogen and water transfer from the older trees (Schoonmaker et al 2007;Teste et al 2009a, b). The finding that the network had scale-free properties suggests that removal of hub trees can have negative effects on the regeneration system.…”

Section: Mycorrhizal Network In Complexmentioning

confidence: 99%

Mycorrhizal networks and complex systems: Contributions of soil ecology science to managing climate change effects in forested ecosystems

Simard

2009

Can. J. Soil. Sci.

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Simard, S.W. 2009. Mycorrhizal networks and complex systems: Contributions of soil ecology science to managing climate change effects in forested ecosystems. Can. J. Soil Sci. 89: 369Á382. Soil ecology science has contributed a rich understanding of natural soil patterns and processes, and played a role in revolutionizing the management of ecosystems. This basic understanding is also providing a foundation for predicting and managing the consequences of climate change on ecosystems, including their resilience to disturbance, biotic diversity, and carbon and nutrient dynamics. To help address the challenges of climate change, future soil ecology research and management would benefit from a complex systems approach, where network and dynamics systems theory are used to predict plant community and ecosystem responses to disturbance. A reductionist approach to management that ignores networks and system dynamics, by contrast, is destined to contribute to ecological degradation as climate changes. In this paper, I describe mycorrhizal networks as models of biological networks in the interior Douglas-fir forests of British Columbia, and the role they play in carbon flux and regeneration dynamics following disturbance. I propose a conservationist approach for managing forest mycorrhizal networks and hub trees that can facilitate native plant migrations, limit exotic plant invasions, and bolster ecological resilience. Interdisciplinary research that integrates the dynamics of multiple, overlapping networks will help develop management practices that sustain ecosystems in our changing climate.Key words: Climate change, complex systems, mycorrhizal networks, species migrations Simard, S.W. 2009. Re´seaux de mycorhizes et syste`mes complexes : contributions de l'e´cologie du sol a`la gestion des effets du changement climatique dans les e´cosyste`mes forestiers. Can. J. Soil Sci. 89: 369Á382. L'e´cologie du sol est une science qui nous a aide´s a`bien comprendre les sols naturels et les processus qui s'y associent; elle a aussi concouru a`re´volutionner la gestion des e´cosyste`mes. Paralle`lement, ces connaissances de base servent de pierre d'assise a`la pre´vision et a`la gestion des conse´quences du changement climatique sur les e´cosyste`mes, notamment leur re´silience face aux perturbations, la diversited es biotes ainsi que la dynamique du carbone et des e´le´ments nutritifs. Pour nous aider a`surmonter les enjeux lie´s au changement climatique, les futures recherches en e´cologie du sol profiteraient d'une approche fonde´e sur les syste`mes complexes, en vertu de laquelle on appliquerait a`la the´orie de la dynamique des re´seaux et des syste`mes pour pre´voir la re´action des populations ve´ge´tales et des e´cosyste`mes aux perturbations. Une approche re´ductionniste qui ne´gligerait la dynamique des re´seaux et des syste`mes contribuerait, en revanche, a`une de´gradation de l'e´cologie, a`mesure qu'e´volue le climat. Dans cet article, l'auteur prend les re´seaux de mycorhizes comme mode`le des re´seaux biologiques ...

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Tree proximity, soil pathways and common mycorrhizal networks: their influence on the utilization of redistributed water by understory seedlings

Cited by 45 publications

References 33 publications

Mycorrhizal networks and distance from mature trees alter patterns of competition and facilitation in dry Douglas-fir forests

Mycorrhizal networks and distance from mature trees alter patterns of competition and facilitation in dry Douglas-fir forests

Impact of wildfire intensity and logging on fungal and nitrogen-cycling bacterial communities in British Columbia forest soils

Mycorrhizal networks and complex systems: Contributions of soil ecology science to managing climate change effects in forested ecosystems

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