Fine root biomass in relation to site and stand characteristics in Norway spruce and Scots pine stands

Abstract

Variations in fine root biomass of trees and understory in 16 stands throughout Finland were examined and relationships to site and stand characteristics determined. Norway spruce fine root biomass varied between 184 and 370 g m(-2), and that of Scots pine ranged between 149 and 386 g m(-2). In northern Finland, understory roots and rhizomes (< 2 mm diameter) accounted for up to 50% of the stand total fine root biomass. Therefore, the fine root biomass of trees plus understory was larger in northern Finland in stands of both tree species, resulting in a negative relationship between fine root biomass and the temperature sum and a positive relationship between fine root biomass and the carbon:nitrogen ratio of the soil organic layer. The foliage:fine root ratio varied between 2.1 and 6.4 for Norway spruce and between 0.8 and 2.2 for Scots pine. The ratio decreased for both Norway spruce and Scots pine from south to north, as well as from fertile to more infertile site types. The foliage:fine root ratio of Norway spruce was related to basal area and stem surface area. The strong positive correlations of these three parameters with fine root nitrogen concentration implies that more fine roots are needed to maintain a certain amount of foliage when nutrient availability is low. No significant relationships were found between stand parameters and fine root biomass at the stand level, but the relationships considerably improved when both fine root biomass and stand parameters were calculated for the mean tree in the stand. When the northern and southern sites were analyzed separately, fine root biomass per tree of both species was significantly correlated with basal area and stem surface area per tree. Basal area, stem surface area and stand density can be estimated accurately and easily. Thus, our results may have value in predicting fine root biomass at the tree and stand level in boreal Norway spruce and Scots pine forests.

Estimating fine-root production by tree species and understorey functional groups in two contrasting peatland forests

“…Thus, pine in general may produce fewer fine roots in peatland forests when the soil nutrient status is better. Similar patterns have also been found for Scots pine FRP in boreal mineral-soil forests (Helmisaari et al 2007;Kalliokoski et al 2010). Thus, the FRP patterns of individual species may differ from the pattern in total FRP, which in our study increased with soil nutrient status.…”

“…The soil nutrient regime also influences both fine-root biomass (FRB) and FRP; however, the directions of the responses have varied among studies in different ecosystems (Santantonio et al 1977;Keyes and Grier 1981;Leibundgut 1981;Hendricks et al 2006), and the measures of soil nutrients reported in individual studies have not allowed for a systematic synthesis (Finér et al 2011). Yet, in the Boreal Zone, most results suggest higher FRB or FRP at poorer sites (Helmisaari et al 2007;Yuan and Chen 2010;Lehtonen et al 2016). For peatlands, the scarce observations so far available suggest a contrasting pattern Laine 1998, 2000;Laiho et al 2014).…”

“…Yet, the FRB of the understorey vegetation accounts for one third of the total FRB in boreal forests (Finér et al 2011). In northern Finland, understorey fine roots and rhizomes (< 2 mm diameter) accounted for up to 50 % of the stand total FRB (Helmisaari et al 2007). In boreal peatland forests of varying nutrient status, the FRP of field-layer vegetation varied from 24 % to 71 % of the total FRP (Finér and Laine 1998).…”

“…Regarding the various species or functional groups, some studies have been done in boreal forests. For example, at boreal mineral soil sites Helmisaari et al (2007) studied the FRB of all major tree species (pine, spruce, birch) and understorey functional groups (shrubs, grasses and herbs) in relation to site and stand characteristics. Kalliokoski et al (2010) reported the belowground interactions in mixed boreal stands of silver birch Betula pendula Roth, Norway spruce Picea abies (L.) H. Karst.…”

Effect of Stand Age on Fine Root Biomass, Production and Morphology in Chinese Fir Plantations in Subtropical China

“…Therefore, fine root could be used as a sensitive indicator of changes in tree physiological traits and environmental conditions [3,12]. Previous results have demonstrated that fine root biomass is dependent upon a wide range of both biotic and abiotic factors, such as climatic conditions (geographical location, precipitation, elevation and annual temperature), soil properties (texture, moisture, chemistry, nutrient availability), and stand characteristics (basal area, stand density, stand age, tree species, and intra-and interspecific competition between plants) [13,14].…”