Boreal peatlands contain approximately 500 Pg carbon (C) in the soil, emit globally significant quantities of methane ( CH 4 ), and are highly sensitive to climate change. Warming associated with global climate change is likely to increase the rate of the temperature‐sensitive processes that decompose stored organic carbon and release carbon dioxide ( CO 2 ) and CH 4 . Variation in the temperature sensitivity of CO 2 and CH 4...

Nutrient limitation is pervasive in the terrestrial biosphere, although the relationship between global carbon (C) nitrogen (N) and phosphorus (P) cycles remains uncertain. Using meta‐analysis we show that gross primary production ( GPP ) partitioning belowground is inversely related to soil‐available N : P, increasing with latitude from tropical to boreal forests. N‐use efficiency is highest in boreal forests, and P‐use effic...

Snow cover is projected to decline during the next century in many ecosystems that currently experience a seasonal snowpack. Because snow insulates soils from frigid winter air temperatures, soils are expected to become colder and experience more winter soil freeze‐thaw cycles as snow cover continues to decline. Tree roots are adversely affected by snowpack reduction, but whether loss of snow will affect root‐microbe interacti...

While there is an emerging view that roots and their associated microbes actively alter resource availability and soil organic matter ( SOM ) decomposition, the ecosystem consequences of such rhizosphere effects have rarely been quantified. Using a meta‐analysis, we show that multiple indices of microbially mediated C and nitrogen (N) cycling, including SOM decomposition, are significantly enhanced in the rhizospheres of diver...

Soil carbon cycling processes potentially play a large role in biotic feedbacks to climate change, but little agreement exists at present on what the core of numerical soil C cycling models should look like. In contrast, most canopy models of photosynthesis and leaf gas exchange share a common ‘Farquhaur‐model’ core structure. Here, we explore why a similar core model structure for heterotrophic soil respiration remains elusiv...

A common finding in multiple CO 2 enrichment experiments in forests is the lack of soil carbon ( C ) accumulation owing to microbial priming of ‘old’ soil organic matter ( SOM ). However, soil C losses may also result from the accelerated turnover of ‘young’ microbial tissues that are rich in nitrogen ( N ) relative to bulk SOM . We measured root‐induced changes in soil C dynamics in a pine forest exposed to elevated CO 2 and...

Nitrogen regulates the E arth's climate system by constraining the terrestrial sink for atmospheric CO 2 . Proteolytic enzymes are a principal driver of the within‐system cycle of soil nitrogen, yet there is little to no understanding of their response to climate change. Here, we use a single methodology to investigate potential proteolytic enzyme activity in soils from 16 global change experiments. We show that regardless of...

Ecology Letters (2011) 14: 187–194 Abstract The degree to which rising atmospheric CO 2 will be offset by carbon (C) sequestration in forests depends in part on the capacity of trees and soil microbes to make physiological adjustments that can alleviate resource limitation. Here, we show for the first time that mature trees exposed to CO 2 enrichment increase the release of soluble C from roots to soil, and that such increases...

For herbaceous species, elevated CO 2 often increases seed production but usually leads to decreased seed quality. However, the effects of increased atmospheric CO 2 on tree fecundity remain uncertain, despite the importance of reproduction to the composition of future forests. We determined how seed quantity and quality differed for pine trees grown for 12 years in ambient and elevated (ambient+200 μL L −1 ) CO 2 , at the Duk...

Despite the importance of nitrogen (N) limitation of forest carbon (C) sequestration at rising atmospheric CO 2 concentration, the mechanisms responsible are not well understood. To elucidate the interactive effects of elevated CO 2 (eCO 2 ) and soil N availability on forest productivity and C allocation, we hypothesized that (1) trees maximize fitness by allocating N and C to maximize their net growth and (2) that N uptake is...

The impact of anthropogenic CO 2 emissions on climate change may be mitigated in part by C sequestration in terrestrial ecosystems as rising atmospheric CO 2 concentrations stimulate primary productivity and ecosystem C storage. Carbon will be sequestered in forest soils if organic matter inputs to soil profiles increase without a matching increase in decomposition or leaching losses from the soil profile, or if the rate of de...

Efforts to characterize carbon (C) cycling among atmosphere, forest canopy, and soil C pools are hindered by poorly quantified fine root dynamics. We characterized the influence of free‐air‐CO 2 ‐enrichment (ambient +200 ppm) on fine roots for a period of 6 years (Autumn 1998 through Autumn 2004) in an 18‐year‐old loblolly pine ( Pinus taeda ) plantation near Durham, NC, USA using minirhizotrons. Root production and mortality...

Increased canopy leaf area ( L ) may lead to higher forest productivity and alter processes such as species dynamics and ecosystem mass and energy fluxes. Few CO 2 enrichment studies have been conducted in closed canopy forests and none have shown a sustained enhancement of L . We reconstructed 8 years (1996–2003) of L at Duke's Free Air CO 2 Enrichment experiment to determine the effects of elevated atmospheric CO 2 concentra...