Soil health, soil genetic horizons and biodiversity^#

Abstract

Maintaining or recovering soil health is becoming a goal of many policies carried out at national, continental and global scales to promote global health. This viewpoint is aimed at stressing the relevance of a holistic approach to soil health assessment and monitoring, which is not only related to soil functional biodiversity but also considers the genetic horizons of the soil profile and not just the topsoil. We highlight that soil health has different connotations depending on the environmental setting and may show high spatial and temporal dynamics. Although the biological activity is often concentrated in the surficial horizon, we report increasing evidence that deep soil horizons host relevant biological communities, which are regulated by soil conditions that are usually different from those present in the topsoil. The processes responsible for the formation of surface and subsurface soil genetic horizons produce soil features that select the presence of organisms. The natural self-organization of soil features is at the basis of the soil classification systems and of their ability to differentiate soil taxa and appreciate pedodiversity. Examples are reported of surface and deep soil genetic horizons as an important interpretative tool of soil functional biodiversity and soil health. Therefore, the assessing and monitoring of soil health should not be carried out at fixed depth, but according to soil genetic horizons. We conclude that the loss of the natural self-organization of genetic horizons is a form of soil health degradation.

Geodiversity Research at the Crossroads: Two Sides of the Same Coin

“…This is one of the alarming omissions in our understanding of soil biodiversity that should be addressed in the future. However, several studies have shown that different pedotaxa types (Garbeva et al, 2004;Fierer and Jackson, 2006;Gagelidze et al, 2018) and different soil horizon types (Ekelund et al, 2001;Fierer et al, 2003;Rosling et al, 2003;Hansel et al, 2008;Doblas-Miranda et al, 2009;Eilers et al, 2012;Costantini and Mocali, 2022) house different assemblages of soil organisms, which indicates soil horizons should be considered in defining the variety of habitats utilized by soil organisms. It has been demonstrated that geographical spaces with low pedodiversity are also poor in above-ground biodiversity (see Ibáñez and Bockheim, 2013;Ibáñez, 2017;and chapters therein;Rillig et al, 2019).…”

Quantifying the Spatial Distribution Pattern of Soil Diversity in Southern Xinjiang and Its Influencing Factors

“…However, both natural factors such as climate, parent material, vegetation, time, and topography, as well as anthropogenic factors such as cultivation, grazing, and construction, influence soil diversity. This complexity, thus, renders the concept and measurement of soil diversity quite intricate [15][16][17]. In the 1990s, Ibáñez et al [18] proposed the use of ecological research methods for analyzing the category diversity of soils within the pedosphere.…”

Inferior plant competitor allocates more biomass to belowground as a result of greater competition for resources in heterogeneous habitats

“…Soils in all natural and managed environments exhibit spatial and temporal heterogeneity ( Lechowicz and Bell, 1991 ; Day et al., 2003a ; Mommer et al., 2012 ; Zhou et al., 2012 ; Costantini and Mocali, 2022 ). Clonal plants exhibit foraging responses to efficiently capture heterogeneous resources in soil, showing morphological plasticity or localized physiological changes in microsites with different nutrient levels ( Hodge, 2004 ; Dong et al, 2015a ; Dong et al, 2015b ).…”