Deterministic uncertainty and complex pedogenesis in some Pleistocene dune soils

Biomechanical effects, lithological variations, and local pedodiversity in some forest soils of Arkansas

“…Other studies which have shown that microtopographic influences, particularly associated with local convergence and divergence of infiltrating and percolated water, can have disproportionately large effects of soil morphology (Price, 1994, Phillips et al, 1996Miller et al, 1999;Wright, 1996). The lack of such evidence in this study is likely attributable to microtopographic effects being overwhelmed by other factors.…”

“…Several studies have suggested or demonstrated that dynamical instability and deterministic chaos can contribute to local-scale soil variability (Culling, 1988;Ibañez, 1994;Liebens and Schaetzl, 1997;Minasny and McBratney, 1999;Phillips, 1998Phillips, , 1999Phillips, , 2001Phillips et al, 1996;Webster, 2000). Instability and chaos leads to divergent soil development whereby small variations and perturbations persist and become exaggerated over time, rather than convergent development characterized by the muting of variations.…”

Pedological memory in forest soil development

“…Persistence of podzol baskets after the tree and its stump are gone is indicated by the presence of baskets in paleosols and their use as evidence of tree spacing in ancient forests (Retallack, 1990, p. 189). This phenomenon was invoked to explain otherwise unexplained spatial variability of B horizon depths in Spodosols in coastal North Carolina (Phillips et al, 1996). Mossa and Schumacher (1993) describe strong evidence for the persistence of pedologic effects of tree roots.…”

Modelling the formation and evolution of soils, towards an initial synthesis

“…This approach was also used by Huggett (1998) to describe the soil evolution of a chronosequence. Phillips et al (1996), studying the short-distance variations of the depth at which the B-horizon of a podzol appears along a slope and of its thickness, showed that such variations cannot be explained by measured variation in the factors of soil formation, but are apparently related to slight variations during pedogenesis (uprooted trees, for instance) that were amplified with time. In a similar vein, when re-analysing the Amazonian soil profiles described by Lucas et al (1996), we see that soils developed over the same parent material show a very clear differentiation, from ferrallitic soils on the plateaus to giant podzols at the bottom of slopes; they explained this evolution through a progression of vertical and lateral transformation fronts along the slopes, leading to clay loss.…”

“…These examples have the common factor of a non-linear amplification of minor variations in the initial conditions (parent material) or of slight disturbances during pedogenesis, such as uprooting. Phillips et al (1996) showed that this type of pedogenesis can be modelled with the help of a non-lineardynamic or deterministic-chaos system and concluded by describing the natural environment as: "there is likely to be some stochastic complexity in addition to any deterministic chaos which may be present." Other examples of pedologic models showing instability and chaos can be found in the literature (Phillips 1993;Ryzhova, 1996;Minasny and McBratney 1999;D'Odorico 2000;Furbish and Fagherazzi 2001).…”