Journal Article

Biomechanical and biochemical effects recorded in the tree root zone – soil memory, historical contingency and soil evolution under trees

Pawlik, Łukasz, Šamonil, Pavel

2018

Overview

Background and aims The changing soils is a never-ending process moderated by numerous biotic and abiotic factors. Among these factors, trees may play a critical role in forested landscapes by having a large imprint on soil texture and chemical properties. During their evolution, soils can follow convergent or divergent development pathways, leading to a decrease or an increase in soil spatial complexity. We hypothesized that trees can be a strong local factor intensifying, blocking or modifying pedogenetic processes, leading to local changes in soil complexity (convergence, divergence, or polygenesis). These changes are hypothetically controlled by regionally predominating soil formation processes. Methods To test the main hypothesis, we described the pedomorphological features of soils under tree stumps of fir, beech and hemlock in three soil regions: Haplic Cambisols (Turbacz Reserve, Poland), Entic Podzols (Žofínský Prales Reserve, Czech Republic) and Albic Podzols (Upper Peninsula, Michigan, USA). Soil profiles under the stumps, as well as control profiles on sites currently not occupied by trees, were analyzed in the laboratory for 20 physical and chemical properties. In total, we analyzed 116 soil samples. The age of trees and time of tree death were determined using the radiometry ( 14 C), dendrochronology and repeated tree censuses. To process the data, we used multivariate statistics, namely, redundancy analyses (RDAs) and principal component analyses (PCAs). The statistical significance of variables was tested using Kruskal-Wallis, Dunn, and permutation tests. To reach the main aims of the present study, we examined the dataset at three levels of data complexity: 1) soil regions, 2) microsite (i.e., tree stump versus control site), and 3) soil horizon. Results Living tree roots and empty or infilled root channels were the most important pedogenic factors that affected the dimensions of soil horizons and the moisture in the root zone under tree stumps. Microsites explained almost 6% of the soil variability ( p  < 0.001, F = 13.99), demonstrating that trees significantly impacted soil chemical properties in the root zone in all regions. In the Albic Podzols soil region, we found evidence of “basket” podzolization. Our results suggest the rapid eluviation of organic matter-sesquioxide complexes under the stump, probably leading to local soil divergence in Albic Podzols. However, soil analyses under the stumps in the Haplic Cambisols soil region suggested local polygenetic changes in soils (e.g., hydromorphic processes). The thickness of the A and B horizons increased, and soil chemistry changed under trees in the Entic Podzol soil region compared to the control profiles. Conclusions In addition to regional environmental factors that manifest themselves in regional pedogenesis and that have a key role in modifying the influence of trees on the soil, the tree species can specifically modify pedogenic processes under standing trees. Trees may influence rate of pedogenesis (hemlock in Albic Podzol region) or even soil evolutionary pathways (beech in Haplic Cambisol region).

• Publisher: Springer Science + Business Media,Springer International Publishing,Springer,Springer Nature B.V
• Subject: Abiotic factors / B horizons / Beech / Biomechanics / Biomedical and Life Sciences / Cambisols / carbon / Carbon 14 / censuses / Chemical properties / Complexity / Contingency / Convergence / Czech Republic / data collection / Dendrochronology / Divergence / Ecology / eluviation / Environmental aspects / Environmental factors / Evolution / Fagus / Growth / Landscape / landscapes / Life Sciences / Michigan / Multivariate analysis / Organic matter / Permutations / physicochemical properties / Plant Physiology / Plant Sciences / Plant species / Podzolic soils / podzolization / Podzols / Poland / principal component analysis / Radiometry / radionuclides / Redundancy / REGULAR ARTICLE / rhizosphere / root channels / Root zone / roots / Roots (Botany) / Soil analysis / soil chemical properties / Soil chemistry / Soil formation / soil heterogeneity / Soil horizons / Soil moisture / Soil profiles / Soil properties / soil sampling / Soil Science & Conservation / Soil texture / Statistical analysis / Statistical methods / stumps / Texture / tree age / Tree stumps / Trees / Trees (Plants)