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Root systems of selected plant species in mesic mountain fynbos in the Jonkershoek Valley, south-western Cape Province

1987; Elsevier BV; Volume: 53; Issue: 3 Linguagem: Inglês

10.1016/s0254-6299(16)31438-7

1727-9321

K. B. Higgins, A. J. Lamb, Brian W. van Wilgen,

Pasture and Agricultural Systems

Twenty-five individuals of 10 species of fynbos plants were harvested 26 years after fire at a mountain fynbos site. The species included shrubs up to 4 m tall, geophytes and other herbaceous plants. The total mass, canopy area and height were determined for shoots. Root systems were excavated by washing away soil around the roots, with water. The mean root:shoot phytomass ratios were lower (0,2) for dominant re-seeding shrubs than for resprouting shrubs (2,3). Herbaceous species (all resprouters) had a mean root:shoot phytomass ratio of 1,5. Roots were concentrated in the upper soil. Sixty-seven percent of the root phytomass was found in the top 0,1 m of soil. The maximum rooting depth ranged from 0,1 m for some herbaceous species to > 3,5 m for deep-rooted shrubs. Fine roots (< 5 mm) contributed at least 59% of the root length and were also concentrated in the upper soil. The root classification scheme of Cannon (1949) was successfully applied to the study, and three primary and two adventitious root types were identified. The rooting patterns of fynbos plants were compared to data from other fynbos areas and to other mediterranean-type shrublands. Dominant fynbos shrubs with deep roots reproduce from seed following fire. Root phytomass can be reduced by 50% following fire in fynbos, while root phytomass remains largely unaffected by fire in Australian heathlands. Vyf-en-twintig individuee van 10 fynbos-plantspesies was 26-jaar na ’n brand in bergfynbos ontgin. Die spesies het struike (tot 4 m hoog), bolplante en ander kruidagtige plante ingesluit. Die totale massa, die oppervlakte van die kroondak en die hoogte was vir bo-grondse dele bepaal. Wortelsisteme was ontgin deur die grond om die wortels met water weg te spoel. Die gemiddelde wortel:loot-biomassaverhoudings was laer (0,2) in die dominante struike wat deur middel van saad verjong, in vergelyking met struike wat na ’n brand spruit (2,3). Kruidagtige spesies (almal spruitende plante) het ’n gemiddelde wortel:loot-biomassaverhouding van 1,5 gehad. Wortels was in die bogrond gekonsentreer. Die grootste gedeelte (67%) van die wortel-biomassa het in die boonste 0,1 m van die grond voorgekom. Die maksimum wortel-diepte het tussen 0,1 m vir sekere kruidagtige spesies, en > 3,5 m vir sekere struike gewissel. Fyn wortels (< 5 mm) het ten minste 59% van die wortellengte bygedra, en was ook in die bogrond gekonsentreer. Die wortelklassifikasieskema van Cannon (1949) was suksesvol op die studie toegepas. Drie primêre en twee bywortel-tipes was uitgeken. Die bewortelingspatrone van fynbos-plante is met die van ander fynbos-areas en met die van mediterreense struikveld-soorte vergelyk. Dominante fynbos-struike met diep wortelsisteme verjong deur middel van saad na brand. Wortel biomassa kan met tot 50% gereduseer word na brand, terwyl wortel-biomassa in Australiese heideveld grootliks onveranderd bly na brand.