Te Roller, Kerry Sharon
Esler, K. J.
Stellenbosch University. Faculty of Science. Dept. of Botany and Zoology .
Invasive plants -- Integrated control -- South Africa -- Western Cape -- Evaluation
Invasive plants -- Integrated control -- South Africa -- Eastern Cape -- Evaluation
Dissertations -- Ecological assessment
Theses -- Ecological assessment
ENGLISH ABSTRACT: One of the most threatening factors to the biodiversity of the Cape Floristic Region is that of invasive alien&#xd; organisms. A contestant for the most noxious of these fynbos threatening organisms is&#xd; Hakea sericea. When left to grow uncontrolled, this small Australian tree forms impenetrable stands that out&#xd; compete the natural vegetation. Due to the threat this plant poses, an extensive and integrated control&#xd; programme was initiated to reduce its numbers to a level where it can no longer compete successfully with the&#xd; indigenous flora. This control programme consists of a carefully devised slash and burn method, chemical&#xd; herbicides and four biological control agents. Little literature surrounding the success of this control programme&#xd; is available. Two data sets, Fugler (1979) and Protea Atlas Project 2001, recording the distribution and density&#xd; of the plant at the height of its invasion and twenty two years later are compared to one another using&#xd; Geographical Information System techniques. Success of control measures is reflected by: (1) a reduction of&#xd; 340 135 ha in total invaded by H sericea, (2) a reduction in density and (3) shifts in patterns of average rainfall,&#xd; altitude, slope and aspect of the areas associated with different density categories of this species. These data&#xd; provide reward for all those involved in the control programme by justifying efforts associated with the control&#xd; of the invader. Furthermore, the findings of this project also highlight the value of the control programme as&#xd; well as indicate how future research should be concentrated in order to perfect the programme.
AFRIKAANSE OPSOMMING: Uitheemse indringerplante is een van die enkele belangrikste faktore wat die Kaapse Fynbos biodiversiteit&#xd; bedreig. In hierdie geval is Hakea sericea een van die mees kompeterende spesies. Hierdie klein Australie&#xd; boompie ontwikkel, indien ongekontroleerd gelaat, tot 'n ondeurdringbare digte woud wat natuurlikke&#xd; plantegroei verdring. Dit is weens hierdie faktor dat ekstensiewe en geintegreerde kontroleringsprogramme&#xd; ontwikkel is om die getalle van bome na die vlakke te verlaag waar dit geen bedreiging vir inheemse flora sal&#xd; inhou nie. Die kontroleringsprogramme maak onder andere van chemiese onkruiddoders, vier biologiese&#xd; beheermiddels, ontbossing en beheerde brande gebruik. Min literatuur is beskikbaar oor die sukses wat verkry&#xd; word met die programme. Twee datastelle elk van Fugler (1979), bevattende data oor digtheid en verspreiding&#xd; van die plante 22 jaar tevore en die Protea Atlas Projek (2001) word vergelyk met behulp van Geografiese&#xd; Inligtingstelsel (GIS) tegnieke. Die sukses van die beheer maatreels word weerspieel in: (1) die totale afname&#xd; van 531 229 ha to 340 135 ha ingedring deur H. sericea, (2) afname in die digtheid en (3) verskuiwing in die&#xd; algemene reenval-, hoogte-, helling- en liggingspatrone wat geassosieer word met die verskillende&#xd; digtheidskatogoriee van die spesie. Die resultate bied regverdiging vir die kontroleringsprogramme van&#xd; indringerplante. Ook beklemtoon die projek die waarde van kontroleringsprogramme en dui aan waarop&#xd; toekomstige navorsing moet konsentreer om die programme te vervolmaak.