Journal Article

Fine root distribution of trees and understory in mature stands of maritime pine (Pinus pinaster) on dry and humid sites

Augusto, Laurent, Transfert Sol-Plante et Cycle des Eléments Minéraux dans les Ecosystèmes Cultivés (TCEM) ; Institut National de la Recherche Agronomique (INRA)-École Nationale d'Ingénieurs des Travaux Agricoles - Bordeaux (ENITAB), Bakker, Mark Ronald, M. R, Achat, David

2006

Overview

Maritime pine (Pinus pinaster) is the main tree cropping species in the Landes of Gascogne forest range in south western France. Soils are nutrient poor, sandy podzosols and site fertility is determined essentially by organic matter content and depth of water table, which is known to limit root growth. We hypothesised, with an ultimate goal of constructing a nutrient uptake model applicable to this region, that the organic top horizons together with the depth of the water table should be the most important parameters related to fine root distribution and presence of associated mycorrhiza. To test this hypothesis, we compared two adult Pinus pinaster stands, contrasting in depth of water table and soil fertility and evaluated fine roots (diameter < 2 mm) of understory species and fine roots and ectomycorrhizal morphotypes of Pinus pinaster down to 1.2 m, using a soil corer approach. Total fine root biomass of Pinus pinaster was not significantly different between both sites (3.6 and 4.5 t ha(-1) for the humid, respectively, dry site), but root distribution was significantly shallower and root diameter increased more with depth at the humid site, presumably due to more adverse soil conditions as related to the presence of a hardpan, higher amount of aluminium oxides and/or anoxia. Fine roots of Pinus pinaster represented only about 30% of total fine root biomass and 15% of total fine root length, suggesting that the understory species cannot be ignored with regards to competition for mineral nutrients and water. A comparison of the ectomycorrhizal morphotypes showed that the humid site could be characterised by a very large proportion of contact exploration types, thought to be more relevant in accessing organic nutrient sources, whereas the dry site had a significantly higher proportion of both long-distance and short-distance exploration types, the latter of which was thought to be more resistant to short-term drought periods. These results partly confirm our hypothesis on root distribution as related to the presence of soil mineral nutrients (i.e. in organic matter), point out the potential role of understory plant species and ectomycorrhizal symbiosis and are a valuable step in building a site-specific nutrient uptake model.

• Publisher: Springer Verlag,HAL CCSD,Springer,Springer Nature B.V
• Subject: Agronomy. Soil science and plant productions / Aluminum / Aluminum oxide / Animal, plant and microbial ecology / Anoxia / Biological and medical sciences / Biomass / Dietary minerals / Drought / ectomycorrhizae / Ectomycorrhizas / Evergreen trees / Fertility / Flowers & plants / Forest soils / forest stands / forest trees / France / Fundamental and applied biological sciences. Psychology / humid zones / Hypotheses / Life Sciences / Minerals / Nutrient sources / Nutrient uptake / Nutrients / Organic matter / Pine / Pine trees / Pinus pinaster / Plant growth / Plant roots / Plant species / Plants / Root biomass / Root distribution / root hairs / root systems / Rooting depth / Roots / Sandy soils / Soil / Soil conditions / Soil depth / Soil fertility / Soil rooting depth / Soil water / Soils / Species / Symbiosis / Trees / Understory / Vegetal Biology / Water depth / Water table / Water table depth
• ISBN: 0002405558000