Soil phytoliths from miombo woodlands in Mozambique

Abstract

This paper describes topsoil phytolith assemblages from 25 loci underneath miombo woodlands on an eco-transect intersecting the Mozambican Rift along a geographical, altitudinal, climatic and botanical gradient. We provide the first comprehensive overview of the phytolith spectrum that defines northern Mozambique's Zambezian floristic zone. Our classifying criteria derive from comparison with previously described and quantified reference collections of trees and grasses growing in the study area. We characterize the sedimentological and soil features of the matrices where phytoliths are found, establishing correlation among geo-edaphic variables and phytoliths. Descriptive statistics along with nonparametric and parametric statistical analyses evaluate phytolith grouping criteria, variation, robustness, and membership. From a taphonomic perspective, we attest that topsoil phytolith assemblages are polygenic and do not represent an episodic snapshot of extant vegetation, but a palimpsest from plants representing various disturbance episodes, succession stages, and ecological trends. Phytoliths retrieved from Mozambican miombo soils do not seem to trace altitudinal, temperature, or precipitation gradients, and no significant differences exist between highland and lowland phytolith assemblages. This article provides a phytolith analog for woodland environments that can guide future paleoenvironmental research. It also confirms that phytolith analysis is able to detect shifts in the woodland/grassland interface.

Differentiation of neotropical ecosystems by modern soil phytolith assemblages and its implications for palaeoenvironmental and archaeological reconstructions II: Southwestern Amazonian forests

“…Given the complexity and heterogeneity of neotropical ecosystems Piperno and Pearsall, 1998a), area-sensitive appraisals of the types of vegetation present and the ability for these to be distinguished by phytoliths are necessary to allow more accurate and finer-grained interpretations of fossil assemblages. This study is the second of a series of papers aimed at characterising phytolith assemblages from Amazonian vegetation types (Dickau et al, 2013), and is similar to studies that have been conducted in other regions of the neotropics (Piperno, 1988) and tropical Africa (Alexandre et al, 1997;Runge, 1999;Bremond et al, 2005;Barboni and Bremond, 2009;Mercader et al, 2011;Aleman et al, 2012;Novello et al, 2012).…”

Water-level variations in Lake Nhauhache, Mozambique, during the last 2,300 years

“…When the lake is relatively deep, the distance to shore is large, preventing phytoliths of terrestrial and telmatic origin from reaching the sampling site. Furthermore, increased wetness during these periods probably results in poor preservation of phytoliths as a consequence of more organic-rich and wetter soils around the lake and relatively fewer large minerogenic grains (Mercader et al 2010(Mercader et al , 2011. On the other hand, during dry periods, when planktonic diatom representation is low and the phytolith abundance is high (zones 2 and 3, Fig.…”

Soil and Plant Phytoliths from the Acacia-Commiphora Mosaics at Oldupai Gorge (Tanzania)

“…Phytogenic silica is released into soils after litter decomposes and discharges both amorphous silica and phytoliths. This process creates a synchronous phytolith record of the plant communities that grew in the soil (Piperno and Becker, 1996;Kerns et al, 2001;Clarke, 2003;Piperno, 2006;Thorn, 2006;Honaine et al, 2009;Morris et al, 2010;Mercader et al, 2011;Novello et al, 2012Novello et al, , 2018Blinnikov et al, 2013;An et al, 2015;Watling et al, 2016;Esteban et al, 2017;Fick and Evett, 2018).…”

“…We explore the soil phytolith assemblages from Acacia-Commiphora woodlands to identify similar environmental contexts in the fossil record, undertaking a concurrent study of phytoliths from local plants to aid in taxonomic classification (Wallis, 2003;Carnelli et al, 2004;Gallego and Distel, 2004;Bremond et al, 2005;Tsartsidou et al, 2007;Barboni and Bremond, 2009;Mercader et al, 2009Mercader et al, , 2010. The comparison of soil and plant phytoliths can assist in tracking the boundary between woodlands and grasslands (Kerns et al, 2001;Morris et al, 2010;Mercader et al, 2011). Elsewhere, this comparison has been helpful to assess phenomena such as time averaging (Alexandre et al, 1997;Blecker et al, 2006;Mercader et al, 2011;Hyland et al, 2013), catchment (Fredlund and Tieszen, 1994;Blinnikov, 2005), and dry months in Oldupai Gorge extend from June to October, with the wettest phase lasting from December to April.…”

“…The comparison of soil and plant phytoliths can assist in tracking the boundary between woodlands and grasslands (Kerns et al, 2001;Morris et al, 2010;Mercader et al, 2011). Elsewhere, this comparison has been helpful to assess phenomena such as time averaging (Alexandre et al, 1997;Blecker et al, 2006;Mercader et al, 2011;Hyland et al, 2013), catchment (Fredlund and Tieszen, 1994;Blinnikov, 2005), and dry months in Oldupai Gorge extend from June to October, with the wettest phase lasting from December to April. Rainfall patterns and localized soil conditions influence the vegetation communities observed in the Serengeti (Anderson and Talbot, 1965).…”