Alterations in forest detritus inputs influence soil carbon concentration and soil respiration in a Central-European deciduous forest

Abstract

In a Quercetum petraeae-cerris forest in northeastern Hungary, we examined effects of litter input alterations on the quantity and quality soil carbon stocks and soil CO 2 emissions. Treatments at the Síkfőkút DIRT (Detritus Input and Removal Treatments) experimental site include adding (by doubling) of either leaf litter (DL) or wood (DW) (including branches, twigs, bark), and removing all aboveground litter (NL), all root inputs by trenching (NR), or removing all litter inputs (NI). Within 4 years we saw a significant decrease in soil carbon (C) concentrations in the upper 15 cm for root exclusion plots. Decreases in C for the litter exclusion treatments appeared later, and were smaller than declines in root exclusion plots, highlighting the role of root detritus in the formation of soil organic matter in this forest. By year 8 of the experiment, surface soil C concentrations were lower than Control plots by 32% in NI, 23% in NR and 19% in NL. Increases in soil C in litter addition treatments were less than C losses from litter exclusion treatments, with surface C increasing by 12% in DL and 6% in DW. Detritus additions and removals had significant effects on soil microclimate, with decreases in seasonal variations in soil temperature (between summer and winter) in Double Litter plots but enhanced seasonal variation in detritus exclusion plots. Carbon dioxide (CO 2 ) emissions were most influenced by detritus input quantity and soil organic matter concentration when soils were warm and moist. Clearly changes in detritus inputs from altered forest productivity, as well as altered litter impacts on soil microclimate, must be included in models of soil carbon fluxes and pools with expected future changes in climate.

The effects of litter production and litter depth on soil microclimate in a central european deciduous forest

“…Soil temperature may also be influenced by soil biochemical processes (Raich and Tufekcioglu 2000;Bernhardt et al 2005); decomposition of organic matter and other microbial processes can release a lesser amount of heat (Khvorostyanov et al 2008). In the colder periods exothermic decomposition processes were significantly greater in litter addition treatments and CO than in detritus removal treatments, as shown by soil respiration values (data in Fekete et al 2014;Kotroczó et al 2014). These higher respiration rates could both be partially due to higher temperatures in litter addition plots due to insulation effects, and could also contribute to warmer conditions.…”

“…During the same period the average dry leaf-litter production was 3585 kg ha −1 and the average amount of total aboveground dry detritus (including branches, twigs, fruit and buds) was 6230 kg ha −1 ). According to the FAO World Reference Base, the soils are Luvisols (Świtoniak et al 2014) with a pH H2O in surface soils (0-15 cm) without detrital manipulation of 5.2, and with a SOM of 39 g kg −1 dry soil Fekete et al 2014).…”

Modelling the effect of changing precipitation inputs on deep soil water utilization

“…Several litter removal experiments that found no significant difference in soil C content between control or litter removal, even after up to 20 years of manipulation, concluded that fine roots must be critical to sustaining soil C (Huang & Spohn, ; Lajtha, Bowden, & Nadelhoffer, ). Furthermore, in a north‐eastern Hungary forest, with 4 years of root exclusion treatment, there was a significant decrease in soil C concentration in the upper 15‐cm soil (Fekete et al, ). We, however, detected no change in soil C contents in 0–10 or 10–20 cm (data not shown).…”

The Path From Litter to Soil: Insights Into Soil C Cycling From Long‐Term Input Manipulation and High‐Resolution Mass Spectrometry

“…Overall, the mineral‐associated fractions are reported to be less vulnerable to decomposition and less responsive to C accumulation from aboveground inputs, indicating that direct litter addition does not necessarily result in rapid or direct accumulation of additional C in the putatively “stable” pools (Bowden et al, ; Lajtha, Bowden, & Nadelhoffer, ; Lajtha, Townsend, et al, ) even when soils are not “carbon saturated” (Mayzelle et al, ). Moreover, the variability of responses among sites may be due to differences in litter decomposition rate as controlled by climate (Fekete et al, ), litter quality (Bowden et al, ), and soil mineralogy that in turn drive the litter‐to‐soil pathway.…”