Changing sources of soil respiration with time since fire in a boreal forest

Abstract

Decomposition of O horizon organic matter made up 20% or less of soil respiration in the younger (o40 years since fire) stands, increasing to $ 50% in mature stands. This is a minimum for total heterotrophic contribution, since mineral soil CO 2 had D 14 C close to or less than those we have assigned to autotrophic respiration. Decomposition of old organic matter in mineral soils clearly contributed to soil respiration in younger stands in 2003, a very dry year, when D 14C of soil respiration in younger successional stands dropped below those of the atmospheric CO 2 .

Frontiers and challenges in soil respiration research: from measurements to model-data integration

“…Capturing the heterotrophic respiration end member can be challenging, due to lateral spatial heterogeneity associated with new C inputs, but also due to vertical changes in the location of microbial decomposition with soil temperature and moisture variations. The autotrophic respiration end member can also vary (albeit less so) within ecosystems, across vegetation types, and seasonally depending on stored carbohydrate (older C) contributions to root respiration (Czimczik et al 2006;Schuur and Trumbore 2006). Finally, 14 C measurements are expensive so studies are limited in Biogeochemistry (2011) 102:1-13 5 the number of replicates in time and space, and interpretation of the results must take into account sample size and uncertainty within the measurements.…”

“…To date, this approach has been used to look at autotrophic and heterotrophic contributions over seasonal to interannual timescales in temperate (Cisneros-Dozal et al 2006;Gaudinski et al 2000), boreal (Czimczik et al 2006;Hahn et al 2006;Schuur and Trumbore 2006), and semi-arid ecosystems; and with manipulations of rain (Borken et al 2006) and snow ). In addition, 14 C partitioning may also be an effective approach to test more specific process-level hypotheses on shorter timescales, particularly when combined with automated soil respiration measurements .…”

Impact of grazing intensity on seasonal variations in soil organic carbon and soil CO 2 efflux in two semiarid grasslands in southern Botswana

“…Autotrophic respiration is driven by photosynthesis and vascular plant activity and not SOC mineralization. CO 2 derived from the mineralization of SOM, however, is independent of photosynthesis and represents a net loss of SOC [31]. Most soil CO 2 estimates do not differentiate between these sources and it is rarely possible to infer anything about changing SOC stores from CO 2 efflux data.…”

“…Vegetation fires affect SOC directly by volatilizing C during combustion [43] and indirectly through modification of the soil temperature, moisture, C and microbial environment [31,44]. If fire results in widespread vegetation death, then organic C input to the soil as ash and part-burned vegetation will increase over the short term.…”

The effects of prescribed fire on soil nematodes in an arid juniper savanna

“…Fire can affect the physical, chemical and biological properties of soil, e.g., aggregate stability, poresize distribution, water repellency, bulk density, decomposer/mineralization food webs, modification of mineralization rates, carbon sequestration, microbial species composition, and nutrient availability [2]. Most studies that consider the effects of fire on soil properties and soil biotic communities have been conducted in forest ecosystems [1,[3][4][5][6].…”