Vegetation zonation on a Natal coastal sand-dune system in relation to salt spray and soil salinity

A number of environmental factors across a coastal sand-dune gradient were monitored over a period of several months. Soil salinities were considerably less than those values usually associated with saline soils, and neither soil salinity nor soil moisture individually correlated with the distribution of vegetation. The patterns of both aerial salt spray and short-term windblown sand correlated well with the species distribution. The survival of cut twigs of four dune scrub species placed at different points on the gradient showed that some factor(s) associated with the aerial environment restricted the scrub species to more sheltered positions. Laboratory studies indicated that both physical damage (associated with windblown sand) and salt spray were implicated in the damage suffered by exposed leaves. ’n Aantal omgewingsfaktore oor ’n kussandduingradiënt is verskeie maande lank gemonitor. Die soutgehalte van die grond was aansienlik laer as waardes wat gewoonlik met soutgrond geassosieer word, en nóg die soutgehalte nóg die watergehalte van die grond kon met die verspreiding van plantegroei gekorreleer word. Die patrone van soutmis sowel as kort-termyn windgewaaide sand het goed met die verspreiding van die plantegroei gekorreleer. Die oorlewing van afgesnyde takkies van vier duinstruiksoorte wat op verskillende plekke in die gradient geplaas is, het getoon dat ’n sekere faktor(e), wat met die lugomgewing verband hou. die struiksoorte tot meer beskutte posisies beperk. Laboratoriumstudies dui daarop dat fisiese skade (veroorsaak deur windgewaaide sand) sowel as soutmis betrokke is by die beskadiging van blootgestelde blare.