Fine Root Distribution in Dehesas of Central-Western Spain

Abstract

A Dehesa is a structurally complex agro-silvo-pastoral system where at least two strata of vegetation, trees and herbaceous plants coexist. We studied the root distribution of trees (Quercus ilex L.) and herbaceous plants, in order to evaluate tree and crops competition and complementarity in Dehesas of Central Western Spain. 72 soil cores of 10 cm diameter (one to two metre deep) were taken out around 13 trees. Seven trees were intercropped with Avena sativa L. and six trees were in a grazed pasture dominated by native grasses. Soil coring was performed at four distances from the tree trunks, from 2.5 (beneath canopy) till 20 m (out of the canopy). Root length density (RLD) of herbaceous plants and trees was measured using the soil core-break method. Additionally, we mapped tree roots in 51 profiles of 7 recently opened road cuts, located between 4 and 26 m of distance from the nearest tree. The depth of the road cuts varied between 2.5 and 5.5 m. Herbaceous plant roots were located mostly in the upper 30 cm, above a clayey, dense soil layer. RLD of herbaceous plants decreased exponentially with depth until 100 cm depth. Holm-oak showed a much lower RLD than herbs (on average, 2.4 versus 23.7 km m )3 , respectively, in the first 10 cm of the soil depth). Tree RLD was surprisingly almost uniform with depth and distance to trees. We estimated a 5.2 m maximum depth and a 33 m maximum horizontal extension for tree roots. The huge surface of soil explored by tree roots (even 7 times the projection of the canopy) could allow trees to meet their water needs during the dry Mediterranean summers. The limited vertical overlap of the two root profiles suggests that competition for soil resources between trees and the herbaceous understorey in the Dehesa is probably not as strong as usually assumed.Abbreviations: RLD -Root length density; Nroot -Number of root; d 50 and d 95 -Depth of 50% and 95% cumulative root density, respectively; CL and ST -Farm names, Cerro Lobato and Sotillo, respectively

Root Structure and Belowground Biomass of Hybrid Poplar in Forestry and Agroforestry Systems in Mediterranean France

“…Most of the workers, owing to resource and time consumption factor coupled with assumption of root presence in that area only, used excavation method and explored fine roots to limited depth, for example, 0.4 m (Ostonen et al, 2005), 0.5 m (Bayala et al, 2004), 0.3-0.5 m (Jiangen et al, 2008), 0.6 m (Tomlinson et al, 1998), 0.8 m (Moreno-Chacon and Lusk, 2004), 0.6-0.9 m (Misra et al, 1998), 1.0 m (Purbopuspito andRees, 2002;Dowell et al, 2009), 1.5 m (Smith et al, 1999) and 2.0 m (Moreno et al, 2005) in different species. In the case of Poplar, few studies like, Puri et al (1994), Fang et al (2007) and McIvor et al (2009) explored 0.3 m, 1.0 m and 1.4 m depth, respectively.…”

“…This understanding does not hold well in the present case since more than 50% of root biomass was distributed beyond this depth. However, there are a few more reports of deep seated coarse root distribution in cottonwood (Rood et al, 2011), loblolly pine (Albaugh et al, 2006), and dehesa vegetation (Moreno et al, 2005).…”

Tree patch distribution drives spatial heterogeneity of soil traits in cork oak woodlands

“…Under this structure, scattered oaks have a positive effect on chemical and physical soil fertility by the accumulation of organic matter (Eviner and Chapin 2003;Gallardo 2003;Rhoades 1997) and improving soil moisture, water availability and soil enzyme activity (Gallardo et al 2000;Garcia et al 2002). This spatial pattern allows the coexistence of plant species with different competition abilities (Ludwig et al 2004;Moreno et al 2005 and ultimately improves the production, quality, and diversity of herbaceous species (Marañón 1986). However, most of the studies concerning the impact of tree spatial distribution on soil heterogeneity have been carried out in holm oak savannas with a tree density of 10-50 trees per hectare, which are mainly used for livestock raising and crop production.…”

“…Furthermore, most of the studies about the spatial variability of soil resources in these ecosystems have been focused in the uppermost soil layer. Surprisingly, there is a lack of information about this variability at deep layers, despite the fact that oaks growing in dehesas show a deep root system with a low root density in the upper 10 cm of the soil (Moreno et al 2005). In addition, there is also limited information about the spatial variability of litter nutrient content and its relationship with the spatial distribution of soil properties.…”

Implementation of a module for risk of ozone impacts assessment to vegetation in the Integrated Assessment Modelling system for the Iberian Peninsula. Evaluation for wheat and Holm oak

“…Likewise, SMC for the /Swp parameter is derived from soil-layer specific SMC, but considering the four layers in the Noah LSM (up to 2 m depth) since Holm oak roots can reach even higher depths (Moreno et al, 2005).…”