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Floralturbation, the mixing of soil by the action of plants, is an important pedologic process in forested areas. The uprooting of trees, the most obvious form of floralturbation, is a natural process found in nearly all forested landscapes. The term uprooting is distinct from such terms as treethrow, treefall, and blowdown, which imply processes that may occur without soil disturbance, as in bole snap. Uprooting is exacerbated by shallow rooting, topographic exposure, weakened condition of the tree, certain cutting practices, and (or) low soil cohesion and shear strength. The root plate of an uprooted tree may deteriorate into a pit-mound pair, the size and shape of which depends on the characteristics of the root plate and the amount of backward displacement during uprooting. This paper (i) provides a synthesis of related terminology on the topics of treefall and uprooting, (ii) examines various lines of evidence for the widespread occurrence of uprooting, (iii) summarizes disturbance cycles for catastrophic uprooting events in different environments, (iv) discusses several examples of the economic import and scale of widespread uprooting events, and (v) reviews environmental factors and silvicultural practices that may lead to increased uprooting or can be used to minimize its likelihood.

This paper reviews the ecological effects of tree uprooting. In many forests, disturbance by uprooting is the primary means of maintaining species richness and diversity. Treefall may be due to exogenous factors or it may be endogenously created, although the former predominate. The canopy gap formed by downed trees is often vital to community vegetation dynamics and successional pathways, by providing high light niches (gaps) for pioneer species, by encouraging release of suppressed, shade-tolerant saplings, and through recruitment of new individuals. Nutrient cycling may be affected by uprooting as subsoil materials are brought to the surface, via additions of woody debris to the forest floor, through exposure of bare mineral soil, and by changes in throughfall chemistry. The influence of the resultant pit/mound microtopography on understorey herb distribution is largely due to microclimatic and microtopographic variation. Tree seedling distribution, however, is related to microtopography primarily through differences in soil morphology, nutrition, and moisture content of mound and pit sites.

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A prominent subsurface zone (layer) of large stones with diameters greater than 6-7 cm occurs in gravelly soil on colluvial aprons in the Lompoc area of California. The soil is mounded and churned by botta pocket gophers (Thomomys bottae). Sedimentological analyses show that the soil within and above the stone zone—and within the gopher mounds—is relatively homogeneous in fine fraction and forms a biomantle. None of the mounds contained stones with long-axis diameters greater than the maximum diameter of gopher burrows, about 6-7 cm. Larger stones gradually subside and form a stone zone. Both field observations and laboratory tests confirm that gopher bioturbation produces stone zones in coarse gravelly soil. This finding, and similar findings in two other recent studies, have important implications for interpreting archaeological site formation, and for interpreting geologic-pedologic processes inasmuch as artifact layers (and nonartifact layers) in some sites entirely may be due to nonanthropic, nongeologic, postdepositional biological agents.

Inasmuch as soils are open systems and rarely, if ever, achieve equilibrium with their environments, it is philosophically sound to view all soils as expressing varying levels of polygenesis as that term has been redefined. Soil genesis and resultant morphology may then be viewed in a comprehensive framework of soil evolution that consists of two linked pathways, one developmental and the other regressive, that reflect interactions of both exogenous and endogenous vectors (vectors are factors, processes, and conditions of pedogenesis). Following this philosophy, a model of pedogenesis is framed in an evolutional paradigm that emphasizes the integrated effects of dynamic and passive pedogenic vectors in directing pathways and in controlling rates of soil genesis through time. The dynamic vectors include energy and mass fluxes, frequencies of soil wetting and drying, water table dynamics, organisms, feedback processes, and pedoturbation. The passive vectors include parent materials, soil chemical environment, stability of geomorphic surfaces, and various evolved soil properties and conditions (accessions). Both sets of vectors vary spatially, and the dynamic vectors, more so than passive vectors, fluctuate through time. The model is expressed as S=f(D,P,dD/dt,dD/dt) where S is the state of the soil or degree of profile evolution, D is the set of dynamic vectors, P is the set of passive vectors, and dD/dt and dP/dt denote change through time t. The model helps explain the apparent minimal development and regressed character of some old soils and the rapid and strong development of some young ones.