Pedological memory in forest soil development

Abstract

Individual trees may have significant impacts on soil morphology. If these impacts are non-random such that some microsites are repeatedly preferentially affected by trees, complex local spatial variability of soils would result. A model of self-reinforcing pedologic influences of trees (SRPIT) is proposed to explain patterns of soil variability in the Ouachita Mountains, Arkansas. SRPIT postulates that trees are preferentially established on patches that are nutrient-rich and rock fragment poor relative to adjacent sites. The biomechanical effects of trees on soil, and decomposition of roots then maintain and reinforce the rock fragment and nutrient differences relative to surrounding soils, increasing the likelihood of successful future tree establishment. The links hypothesized in the SRPIT model are dynamically unstable, which would be necessary for the self-reinforcing mechanisms to operate. Soil variability in 16 study plots is dominated by local, within-plot variability, pointing to highly localized biological effects and consistent with the SRPIT model. Within each 0.127 ha plot, 4-11 different series, and 4-9 different rock fragment classes were found. Of the 10 paired pits at each plot, 3-7 pairs had different series in pits typically less than 1 m apart. On average, each of the 16 plots had 6.3 different soil types, 6 different rock fragment classes, and 60% of the sample pairs differing in soil series. Richness-area analysis of soil series, and of rock fragment classes, both indicate that pedodiversity is dominated by within-plot rather than between-plot variability. The vertical variations in the concentration of rock fragments in 40 of 58 soil pits is consistent with redistribution of soil material by tree throw, and there is also evidence of rock fragment displacement by tree growth and deposition in stump holes. Overall, results suggest that soil morphological effects of individual trees are an important source of soil spatial variability in forests, and that such effects are non-random over time. Thus even relatively homogeneous areas may be characterized by tree-rich patches which support repeated generations of trees, and tree-poor patches which more rarely host trees. #

Base-cation Cycling by Individual Tree Species in Old-growth Forests of Upper Michigan, USA

“…There are two likely explanations for this patterning: either local differences in the soil parent materials control the distribution of individual tree species (van Breemen 1995), or the trees themselves are able to initiate and maintain differences in soil fertility (Miles 1985;Phillips and Marion 2004). Support for the first explanation was obtained in northern hardwood stands of northwestern Connecticut.…”

“…The 'shifting mosaic' theory argues that the diverse mosaic of individual species and patches of trees is temporary and that each part of the landscape undergoes a succession of developmental stages (Clark 1991;Frelich et al 1993;Zhang et al 1999). In contrast, the influence of individual trees or patches of trees may extend for repeated generations (i.e., 'pedological memory') because of the 'self-reinforcing pedologic influence of trees' (Miles 1985;Phillips and Marion 2004). The longevity of pedogenic effects from different species can be estimated by comparing annual inputs of nutrients with outputs and accretion of nutrients in biomass (Clayton 1979).…”

Rock fragment distributions and regolith evolution in the Ouachita Mountains, Arkansas, USA

“…These results have been discussed elsewhere (Phillips and Marion, 2004), and will be reviewed here briefly in the context of the potential role in rock fragment transport. Notwithstanding the contingent 'snapshot' nature of the data, the inventories do give a general idea of the portion of the soil surface influenced by tree effects.…”

Tree seedlings: how do they establish in spontaneously developed forests? A study from a mountainous area in the Czech Republic

“…Surrounding (Springar 1995;Hersperger and Forman 2003;Rehounkova and Prach 2006), history (Peterken and Game 1984;Vojta 2007) and stochastic events (Brokaw and Busing 2000) influence species composition. Soil conditions are also important (e.g., Ferrell 1953;Smilauerova 2001;Phillips and Marion 2004), and the same is true for herbivory (e.g., De Steven 1991), light conditions (Górski et al 1977) or mycorrhiza (Smilauerova 2001;Dickie and Reich 2005;Dickie et al 2007).…”