Predicted World Distribution of C3 and C4 Grass Phytoliths

Abstract

6The shapes of individual opal phytoliths from grasses, silica bodies formed in the epidermal cells of the leaf, are indicators of the ~ and C 4 photosynthetic pathways. Pooid phytoliths are circular, rectangular, elliptical, crescent or oblong forms and occur primarily in C 3 grasses, which are concentrated in high latitudes or high elevations. Chloridoid phytoliths are saddle-shaped, and occur dominantly in C 4 grasses that grow in warm, arid to semiarid regions in which the available soil moisture is very low. Panicoid phytoliths include many variations of crosses and dumbbells, and occur largely in C 4 grasses that flourish in warm, tropical to subtropical regions with a moderate amount of available soil moisture.Identifiable grass phytoliths, concentrated from soils, paleosols, sediment, archaeological sites and sedimentary rock, can be used to reconstruct the Cenozoic environment of a site or region. Taxa of the subfamily Pooideae grow in the higher latitudes and elevations. Taxa of subfamilies Chloridoideae and Panicoideae are restricted to the tropics and subtropics. The majority of extensive grasslands occur in continental interiors and are the dominant sources of identifiable phytoliths. High ratios of pooid to total pooid, chloridoid and panicoid phytoliths imply cool temperatures in the region. High ratios of chloridoid to total chloridoid and panicoid phytoliths imply a warm arid or semiarid region. Because the sources of phytoliths may be local or remote, the locations and directions of major wind belts and ocean currents must be considered in any interpretation.

An ethnoarchaeological study of livestock dung fuels from cooking installations in northern Tunisia

“…Phytoliths that were unidentifiable because of dissolution were counted and recorded as weathered morphotypes. Morphological identification was based on modern plant reference collections from the Mediterranean area (Albert and Weiner, 2001;Albert et al, 2008Albert et al, , 2011Portillo et al, 2014) and standard literature Brown, 1984;Piperno, 1988Piperno, , 2006Mulholland and Rapp, 1992;Rosen, 1992;Twiss, 1992). The terms used follow the International Code for Phytolith Nomenclature (Madella et al, 2005).…”

Dinâmica De Rampa De Colúvio Na Superfície De Palmas/Água Doce Durante O Quaternário Tardio – Bases Para Compreender a Evolução Das Encostas No Planalto Das Araucárias

“…A partir do horizonte 3Cb, ocorre tendência de acréscimo de 71,43% para 100% até o topo do horizonte 5Cb (Figura 5). Nesse intervalo ocorre o domínio de gramíneas Pooideae (Rondel e Trapeziform) adaptadas a regime climático frio (TWISS, 1992;BREMOND et al, 2008;COE et al, 2014). Na base do horizonte 5Cb a aplicação do índice aponta para valor de zero, mas não deve ser tomado como indicativo de condições climáticas quentes como verifi cado para os níveis Ap e 2Bb, devido ao reduzido número de fi tólitos passíveis de aplicação do índice.…”

Caracterização de fitólitos de plantas e assembleias modernas de solo da caatinga como referência para reconstituições paleoambientais

“…Os índices fitolíticos permitem inferir parâmetros de vegetação, como o índice de densidade da cobertura arbórea (D/P), o índice de densidade da cobertura por palmeiras (Pa/P), o índice de estresse hídrico (Bi) e o índice climático (Ic), que indica a adaptação da formação vegetal a uma temperatura mínima e/ou pressão parcial de Dióxido de Carbono (pCO 2 ) forte (zonas de altitude) (Coe et al 2012). Esses índices já foram largamente utilizados em trabalhos com fitólitos extraídos de solo na África (Twiss 1992, Alexandre et al 1997, Bremond 2003, Bremond et al 2005a, 2005be 2008, Barboni et al 1999e 2007, entre outros) e no Brasil , Coe 2009, Coe et al 2012a, 2012b, 2013, 2014be 2015, Augustin et al 2014, Barros et al 2016, Parolin et al 2017.…”