Coexistence of Seeders and Sprouters in a Fire-Prone Environment: the Role of Ecophysiology and Soil Moisture

The wide variety of flowering plant species that occur in fynbos communities can be divided into two broad categories on the basis of their mode of regeneration after fire: sprouters and non-sprouters (or seeders; see Chap. 4) The loss of the ability to sprout is considered to be a specialized developmental trait in woody dicotyledons, with sprouting being considered conservative in evolutionary terms (Wells 1969; see Chap. 7). Sprouters tend to be more resilient under a range of fire regimes than seeders often showing remarkable powers of vegetative recovery. Keeley (1977) and Specht (1981b) suggested that the relative dominance of sprouters in fire-prone shrubland communities is a consequence of the competition between adult sprouters and seedlings of non-sprouters. Generally, sprouters have a competitive advantage over seeders after fires because they grow more rapidly reach reproductive maturity sooner, and are better competitors tor light moisture and space. During long fire-free intervals, sprouter adults become self-thinning, and mortality is driven by density-dependent competition and senescence (Parker 1984). This results in the formation of gaps in the vegetation canopy after fire due to the lack of recovery of senescent sprouters. These gaps can be exploited by seedlings.