Premium
Growth of seedlings of the invasives, Acacia saligna and Acacia cyclops in relation to soil phosphorus
Author(s) -
WITKOWSKI E. T. F.
Publication year - 1994
Publication title -
australian journal of ecology
Language(s) - English
Resource type - Journals
eISSN - 1442-9993
pISSN - 0307-692X
DOI - 10.1111/j.1442-9993.1994.tb00492.x
Subject(s) - cyclops , acacia , biology , phosphorus , botany , agronomy , horticulture , ecology , chemistry , organic chemistry
Acacia saligna and Acacia cyclops are the dominant invasive alien plants of phosphorus‐poor, sand‐plain, lowland fynbos and the relatively phosphorus‐rich strandveld vegetation of the southwestern Cape of South Africa, respectively, but their ranges overlap. Seedlings of the two species were grown in pots, in isolation and mixed, in up to seven treatments supplying a broad gradient in phosphorus (P) availability. Acacia saligna seedlings grew taller and had greater dry mass than those of A. cyclops at each level of P, but both peaked in response to the same relatively high soil P level and then tended to decline. Root : shoot ratios did not differ in response to P, but were greater in A. saligna . In mixture, A. saligna had a higher dry mass than A. cyclops at each level of P, but the relative differences between species were no greater than in isolation. Depth penetration of the soil by the tap root of A. saligna seedlings was over three times as rapid as that of A. cyclops over a 30 day period. The higher absolute growth rates of A. saligna were not related to seed size or seed nitrogen and P contents, as these were greater in A. cyclops . The contrasting distributions of the acacias do not appear to be a response to P availability per se , but possibly to the interaction of P with other factors such as moisture availability.