Floristic diversity of an eastern Mediterranean dwarf shrubland: the importance of soil pH

Abstract

bstract Questions: Does plant species richness and composition of eastern Mediterranean dwarf shrubland (phrygana) correlate with soil pH? How important is the effect of pH on species diversity in relation to other environmental factors in this ecosystem? What is the evolutionary background of the diversity-pH relationship? Location: Western Crete, Greece. Methods: Species composition of vascular plants, soil and other environmental variables were sampled in 100-m 2 plots on acidic and basic bedrock in phrygana vegetation. The relationships between species composition and environmental variables (including climate) were tested using canonical correspondence analysis, and relationships between species richness and environment using correlation and regression analyses. Data were analysed separately for different plant functional types based on life form and life span. Results: Although soil pH varied across a narrow range (5.9-8.1), species composition changed significantly along the pH gradient within all plant functional types. For most functional types, the effect of soil pH on species composition was stronger than that of other environmental variables. Species richness of annuals, geophytes and suffruticose chamaephytes increased with soil pH, while richness of hemicryptophytes and shrubs was not correlated with pH. Conclusions: The results are consistent with the evolutionary species pool hypothesis. High numbers of calcicole annuals, geophytes and suffruticose chamaephytes may be a result of the evolution of these groups on base-rich dry soils in the Mediterranean climate. In contrast, hemicryptophytes, a life form typical of the temperate zone, evolved on both acidic and basic soils and therefore their species numbers do not respond to soil pH across the narrow range studied. The lack of a relationship between shrub species richness and pH is difficult to explain: it may reflect the more diverse or older origin of Mediterranean woody species and their conservative niches.

Phosphorus application and liming effects on forage production, floristic composition and soil chemical properties in the Campos biome, southern Brazil

“…(), even small changes in soil pH can lead to changes in floristic diversity, but such changes still depend on pedoclimatic conditions of the grasslands. In Continental Europe, the presence of a larger pool of vascular plant species adapted to high‐pH soils than the pool of plant species adapted to acidic soils explains the increase in species diversity of native vegetation with increasing soil pH (Schellberg et al ., ; Nilsson et al ., ; Hejcman et al ., ; van der Wal et al ., ; Chytrý et al ., ). However, the natural pastures of southern Brazil occur on acidic soils under subtropical conditions, with pH typically in the range from 4·4 to 5·1 (Rheinheimer et al ., ; Gatiboni et al ., ; Oliveira et al ., ).…”

High species richness in hemiboreal forests of the northern Russian Altai, southern Siberia

“…Many species per plot of 100–1000 m 2 have also been reported from regions with a mediterranean‐type climate, especially eastern Mediterranean shrublands (Naveh & Whittaker ; Bergmeier ; Chytrý et al. ), South African fynbos (Naveh & Whittaker ; Schmiedel et al. ) and tropical savannas such as the Brazilian cerrado (Eiten ).…”

“…In areas of 1-50 m 2 , the greatest richness of vascular plants has been reported from temperate European dry and semi-dry grasslands on base-rich soils (van der Maarel & Titlyanova 1989;Kull & Zobel 1991;Klimeš et al 2001;Vasilevich 2009) and mountain grasslands of Argentina (Cantero et al 1999). Many species per plot of 100-1000 m 2 have also been reported from regions with a mediterranean-type climate, especially eastern Mediterranean shrublands (Naveh & Whittaker 1979;Bergmeier 1995;Chytrý et al 2010a), South African fynbos (Naveh & Whittaker 1979;Schmiedel et al 2010) and tropical savannas such as the Brazilian cerrado (Eiten 1978).…”

The relationship between plant species richness and soil pH vanishes with increasing aridity across Eurasian dry grasslands

“…through drought stress; Tilman & Haddi, 1992) and soil pH (through cation leaching and accumulation; Alexander, 2013). While many studies report an increase in fine-scale plant species richness of dry grasslands with increasing precipitation (Adler & Levine, 2007;Chytr y et al, 2007;Cheng et al, 2011) and a negative relationship between soil pH and precipitation (Chytr y et al, 2007(Chytr y et al, , 2010, it is largely unknown whether and by how much precipitation might impact on the species richness-soil pH relationship. The effects of soil pH on species richness have rarely been studied over broad areas, in which climatic factors become increasingly important drivers of vegetation patterns (Field et al, 2008).…”