Seasonal allocation of biomass and resources in the geophytic species Haemanthus pubescens subspecies pubescens in lowland coastal fynbos, South Africa

Abstract

The seasonal biomass and resource allocation patterns of a perennial geophytic species, Haemanthus pubescens subspecies pubescens, were investigated. Four phenophases for the species were identified and the annual patterns of dry mass and resource allocation were identified from individuals sampled from natural populations. From the results, four general resource allocation patterns were identified: (1) mobile macronutrients (N, P and K) and Cu; (2) immobile macronutrients (Mg and Ca) and Mn; (3) soluble carbohydrates, starch, Zn and Fe; and (4) Na, all with their own distinctive allocation patterns. This study confirms distinct allocation patterns between the resources and biomass. Furthermore, it was found that environmental constraints contributed towards the differential seasonal allocation patterns of the resources and biomass. The development of an underground storage organ is regarded as an evolutionary mechanism to cope with soils of a low nutrient status, characteristic of the Cape fynbos, and as a strategy for the protection of dry matter and resources against seasonal periodic droughts and fires. Die seisoenale biomassa en reserwe toekenningspatrone van ’n meerjarige geofiet spesie, Haemanthus pubescens subspecies pubescens, is ondersoek. Vier fenofases is vir hierdie spesie geïdentifiseer en die jaarlikse patrone vir droë massa en reserwe toekennings is geïdentifiseer vanaf individue wat uit natuurlike populasies gemonster was. Uit die resultate is vier algemene reserwe toekenningspatrone geïdentifiseer vir: (1) mobiele makrovoedingselemente (N, P en K) sowel as Cu, (2) immobiele makrovoedingselemente (Mg en Ca) sowel as Mn, (3) oplosbare koolhidrate, stysel, Zn en Fe, en (4) natrium, almal met hul eie kenmerkende toekenningspatrone. Hierdie studie bevestig opvallende verskille tussen die toekenning van reserwes en die biomassa. Verder is dit ook gevind dat omgewingsbeperkings bydra tot die differensiële seisoenale toekenningspatrone van reserwes en biomassa. Om dié rede word die ontwikkeling van ’n ondergrondse stoororgaan beskou as ’n meganisme om die kenmerkende lae voedingstatusgronde van die Kaapse fynbos, te hanteer. Dit word ook as ’n strategie beskou om die minerale- en droë materiaal reserwes te beskerm teen seisoenale periodieke droogtes en veldbrande.