Response of the fine root system in a Norway spruce stand to 13 years of reduced atmospheric nitrogen and acidity input

Abstract

Atmospheric inputs of acids and nitrogen (N) have altered growth and vitality of forests for decades, but there is a lack of understanding concerning the response of these forests to reduced deposition. We studied fine root parameters of a Norway spruce stand treated with reduced input (clean rain) for 13 years. Fine roots of the clean rain plot had smaller N and Al contents, however, fine roots in the subsoil were still subjected to soil acidity and Al toxicity as indicated by a fine root Ca/Al ratio of less than 0.5. The treatment effect was most pronounced in the organic layer of the clean rain plot where fine root biomass increased by 66% and the live/dead ratio of fine roots increased by more than 100%. The elevated live/dead ratio was attributed to reduced mortality and faster decomposition of fine root litter. The latter was supported by a positive relationship between live/dead ratio and manganese content of fine roots. In contrast to the organic layer, fine root biomass was not different in the mineral soil. However, at 20-40 cm fine root diameter was greater and specific root tip density was smaller than in the topsoil likely because of strong N limitation as indicated by a C/N ratio of >50. Based on these morphological changes we postulate differing functional properties of fine roots in the organic layer and mineral soil below 20 cm depth. Further, our results suggest that Picea abies is able to adapt morphology and functional traits of its root system following reduced N availability.

Fine-root carbon and nitrogen concentration of European beech (Fagus sylvatica L.) in Italy Prealps: possible implications of coppice conversion to high forest

“…Fine-root C:N ratio data in the present study ranged from 39.6 to 93.4 (Figure 1) and were of the same magnitude as other published values for the same tree species (Persson and Ahlström, 2002; Ayres et al, 2004; Zang et al, 2011). Moreover, we found an increase of fine-root C:N ratio with depth that was related to the depth-dependent pattern of N concentration (Figure 1).…”

Characteristics of Free Amino Acids (the Quality Chemical Components of Tea) under Spatial Heterogeneity of Different Nitrogen Forms in Tea (Camellia sinensis) Plants

“…In the current study, root development was improved by U. NH 4 + treatment, which was consistent with the above studies [25,26]. As the most active part of the tea root system, absorbing roots contributed most to the absorption of water and most nutrients [27]. The U. NH 4 + treatment may have improved the growth of absorbing roots, which helped increase the absorption of water and nutrients in tea plants.…”

The Responses of Forest Fine Root Biomass/Necromass Ratio to Environmental Factors Depend on Mycorrhizal Type and Latitudinal Region

“…Global information on fine root traits is particularly important to advance our understanding and to predict plant and ecosystem processes under changing environmental conditions (McCormack et al, ). The fine root B/N ratio in forest ecosystems combines many important ecological processes including production, mortality, and decomposition of fine roots and can be served as a powerful metric for identifying the absorptive capacity of fine root systems (Persson & Stadenberg, ; Zang et al, ). Consequently, it is necessary to use the extensive literature on fine root biomass and necromass to elucidate large‐scale variation characteristics of B/N ratio and link it with tree mycorrhizal traits and environmental conditions (Iversen et al, ).…”

“…Fine root production, death, and decomposition collectively determine the total size of a root population that is fine root biomass (the living fine roots) and necromass (the dead fine roots). Both parameters indicate how trees interact with their environments (McCormack et al, ; Zang et al, ). The biomass/necromass (B/N) ratio of fine roots can be a parameter of interest for assessing the way the forest ecosystem functions (Bakker, ).…”