Wood structural diversity in fynbos, chaparral, and maquis: a preliminary estimation

Abstract

Fynbos, a shrubland from the Cape Floristic Region in South Africa, is one of five Mediterranean-climate biomes alongside maquis in the Mediterranean Basin, chaparral in California, matorral in Central Chile and kwongan in Southwestern Australia. We compiled the available information on the wood anatomy of 226 species belonging to 65 genera of 14 families that occurred in fynbos and compared this dataset with the published data on wood diversity in Californian chaparral and Israeli maquis. “Carlquist’s Law”, i.e., the association between the ground tissue made of fibre tracheids and low vessel grouping, has been confirmed for the fynbos plants. The lack of ring porosity and very low incidence of semi-ring-porous woods is the most prominent difference of the fynbos from the other two vegetation types. These features are attributed to the paucity of deciduous plants in fynbos which is probably associated with the poor-nutrient soils in this biome. The fynbos differs from chaparral and maquis also in the greatest percentage of the species having no tracheids in their wood as well as with the lowest incidence of helical thickenings on the vessel walls. These differences could be explained by the lower tolerance of fynbos shrubs to seasonal drought due to the relatively mild dry season in this biome. We also found that some differences between fynbos, chaparral, and maquis in the incidences of fibre tracheids and vasicentric/vascular tracheids associated with large vessel groups can be at least partly explained by different systematic compositions of their floras. The higher percentage of distinct growth rings, greater vessel diameter, and lower vessel frequency in maquis compared with fynbos and chaparral can be attributed to a common occurrence of relatively tall trees in this vegetation.