Temporal changes in spatial patterns of soil moisture following disturbance: an experimental approach

Abstract

Summary 1We quantified changes in spatial heterogeneity of soil moisture over 2.5 years in a Pinus elliottii Engelm. forest, following disturbance and succession. We harvested or girdled upper canopy trees and measured three components of heterogeneity -global (non-spatial) variability, spatial dependence and temporal persistence -in replicate plots, using sample points arrayed at a fine scale (0.5-6 m) nested within a coarser scale (5-60 m). 2 Global variability increased after disturbance and then declined, eventually returning to the level recorded in an undisturbed plot. Harvesting resulted in greater, more rapid and more prolonged changes in global variability than girdling. 3 Geostatistical parameters for measuring spatial dependence were largely unaffected by disturbance. Spatial dependence was, however, quite variable across replicate plots and was stronger at the finer sampling scale. 4 Spearman rank correlations showed that the spatial pattern of soil moisture had greater long-term persistence in the undisturbed and girdled plots than in the harvested plots. 5 Some elements of spatial heterogeneity appear to vary over time in a predictable manner. Detection of temporal trends may be improved if multiple components of heterogeneity are quantified, more than one scale of observation is used, replicate plots are employed and sole reliance on geostatistics is avoided.

Un incendie modifie la configuration spatiale de la disponibilité des éléments nutritifs dans les sols de forêts de Pinus canariensis

“…Spatial heterogeneity of essential plant resources on different spatial scales is ubiquitous in natural ecosystems (Gallardo, 2003;Guo et al, 2002;Jackson and Caldwell, 1993;Nicotra et al, 1999;Robertson and Gross, 1994;Robertson et al, 1997;Schlesinger et al, 1996). This spatial heterogeneity in the availability of soil resources can influence processes at the individual, population and community levels (Gallardo et al, 2006;Hutchings et al, 2003).…”

“…This spatial heterogeneity in the availability of soil resources can influence processes at the individual, population and community levels (Gallardo et al, 2006;Hutchings et al, 2003). Spatial variability in available soil nutrients may change during succession, or even within a single year, but patches of plant-available nutrients may reappear at the same spatial locations at irregular points in time (Cain et al, 1999;Gross et al, 1995;Guo et al, 2002;Ryel et al, 1996). The effect of disturbance on the spatial pattern of soil resources has been addressed by several authors.…”

Statistical Methods for the Analysis of Soil Spatial and Temporal Variability

“…The coefficients of variation were significantly different between habitats. Other examples of the use of the coefficient of variation for the assessment of the spatial and temporal variabilities can be found in Ehrenfeld et al (1997) and Guo et al (2002). The standard deviation and, hence, the coefficient of variation does not incorporate spatial and/or temporal information and therefore doesn't provide a representation of the nature of the spatial and/or temporal behaviour of a given soil property.…”

“…A value of this coefficient equal to one indicates a perfect temporal stability between time instants j and k, and thus identity of ranks for any location whereas a lack of temporal stability implies that r s = 0. Many researchers used this concept to evaluate the temporal stability of different soil properties, among them, Campbell et al (2001), Douaik (2005), Farley & Fitter (1999), Guo et al (2002), Heathman et al (2009), Hu et al (2011), Reichardt et al (1993, Si (2002), and Wendroth et al (1999). The Spearman rank correlation coefficient is a non parametric statistics therefore it can be used even for non normally distributed data.…”

Research on the relationship between vegetation and soil resource patterns on lands abandoned at different times

“…The factors and processes that determine soil resource patterns in arid or semi-arid ecosystems have been discussed in research reports over the past two decades (Guo et al, 2002;Okin et al, 2008;Robertson et al, 1997). Soil resources are primarily controlled by pedogenic factors, such as climate, topography and vegetation (Oueslati et al, 2013).…”