Assessment of fleshy-fruited invasive alien plants in eastern South African grasslands using community perceptions, seed germination and dispersal, and repeat photography.

Doctoral Degree. University of KwaZulu-Natal, Pietermaritzburg.

Invasive fleshy-fruited trees and shrubs have been an increasing problem in many grassland systems over the past few decades because they change vegetation structure and threaten native plant diversity. However, forest ecosystems have received more attention than grasslands because fleshy-fruited plants are relatively dominant in the forest. This study aimed to address gaps in knowledge of fleshy-fruited invasive alien plants in montane grassland ecosystems of South Africa by studying socio-economic and environmental impacts, community perceptions, potential animal seed dispersal and population dynamics over time of dominant fleshy-fruited invasive alien plants. In the grassland biome of South Africa, the dominant fleshy-fruited invasive species come from the Rosaceae family and include Cotoneaster pannosus, Pyracantha angustifolia, and Rosa rubiginosa, which were the focus species for this study. These are widespread and damaging invasive plants within the grassland biome of many other countries, so understanding how each spread may assist in managing the species regionally and internationally. In Chapter 2, I reviewed the research efforts on fleshy-fruited invasive alien plants in grassland ecosystems and mosaics. The systematic review showed seed dispersal was the most studied concept of fleshy-fruited invasive alien plants in grasslands. In Chapter 3, this multifaceted study collated data from communities living within areas invaded by the species on their perceptions of these species through in-person, online and telephonic questionnaires to understand the socio-economic context of invasions and how people contribute to both spread and control. Questionnaire surveys showed that the general public does not regard P. angustifolia as a problem, while landowners and conservationists regard the species as a problem. The community has attempted to use herbicides, fire, and mechanical control, but the population of these invasives is still increasing, and the community has requested clearing assistance from the government. In Chapter 4, the rate of spread was assessed by comparing recent photographs with historical ones. Repeat photography showed that fleshy-fruited invasive alien plants have increased in the grasslands over the past 12 years. In Chapter 5, I also assessed bird potential preference using choice trials. Fruit selection trials revealed significant differences among plant species by various frugivorous birds. In Chapter 6, the collection of excreta and subsequent seedling emergence from mammalian faecal samples assessed the involvement of mammals in the seed dispersal of fleshy-fruited invasive alien plants. Mammalian faeces collection showed medium to large-sized mammals to be effective seed dispersal agents of these invasive plants. The study introduced a novel approach using Google Street View archives to assess vegetation population changes and provide a cost-effective means to study vegetation dynamics and ecosystem responses to environmental change. By identifying factors influencing fruit selection by frugivorous birds and locally occurring terrestrial mammalian species as effective seed dispersers, the research offers insights into the ecological mechanisms driving the spread of these invasive plants. Understanding these dynamics informs targeted intervention strategies for managing invasive plants more effectively, contributing to conservation efforts and biodiversity preservation. This study also highlights the need for further collaborative research to address the multifaceted challenges posed by invasive plant species. Iqoqa. Izihlahla ezizimilelayo ezikhiqiza izithelo ezidlekayo kanye namahlamvu sekube inkinga eqhubekayo ezindaweni eziningi ezingamadlelo eminyakeni yamashumi eyedlule ngoba kushintsha uhlelo lokumilayo futhi kuyingozi ekwehlukeni kwezitshalo zemvelo. Yize noma kunjalo, impilandawonye yehlathi isithole ukunakwa okukhulu ngaphezu kwamadlelo ngoba izitshalo ezikhiqiza izithelo ezidlekayo sezidlondlobele kakhulu ehlathini. Lolu cwaningo luhlose ukubuka amagebe olwazi lwezitshalo ezizimilelayo ezikhiqikiza izithelo ezidlekayo emadlelweni empilandawonye aseNingizimu Afrika ngokucwaninga imithelela yempilo yezomnotho kanye neyemvelo, ukuqonda komphakathi, ukuhlwanyela kwembewu izilwane okungaba umthelela kanye nokwehlukahluka kwezinhlobo ngokuhamba kwesikhathi kokudlondlobala kwezitshalo ezizimilelayo ezikhiqiza izithelo ezidlekayo. Kwibhayomi yamadlelo aseNingizimu Afrika, izinhlobo zezitshalo ezizimilelayo ezikhiqiza izithelo ezidlekayo ezidlondlobele emndenini weRosaceae futhi kufaka neCotoneaster pannosus, iPyracantha angustifolia, kanye neRosa rubiginosa, okwakuyizinhlobo lolu cwaningo olugxile kuzo. Lezi zitshalo ezizimilelayo ezisabelele futhi ezilimazayo phakathi kwibhayomi yamadlelo amazwe amaningi, manje ukuqonda ukuthi kusabalala kanjani ngakunye kungalekelela ukwengamela izinhlobo ngokwezifunda kanye nasemhlabeni wonke jikelele. Ngibuyekeze imizamo yocwaningo ezitshalweni ezizimilelayo ezikhiqiza izithelo ezidlekayo kwimpilonhlaliswano yamadlelo kanye nemihlobiso yazo ukukhomba amagebe ocwaningo. Amasaveyi ohlamibuzo akhombisa ukuthi umphakathi awuboni i-P. angustifolia njengenkinga, ngesikhathi abanikazi bomhlaba kanye nabongi bomhlaba bebuka lezi zinhlobo njengenkinga. Isithwebuli esiphindiwe sakhombisa ukuthi izitshalo ezizimilelayo ezikhiqiza izithelo ezidlekayo sezenyukile emadlelweni esikhathini esingaphezu kweminyaka eyi-12 eyedlule. Ukuhlola izithelo ezikhethekile kwaveza umehluko omkhulu phakathi kwezinhlobo zezitshalo ngezinyoni ezahlukene ezidla izithelo. Indle yezilwane ezincelisayo eyaqoqwa yakhombisa ukuthi kusuka ezilwaneni eziphakathi nendawo ezincelisayo kuya kwezinkulu zinomthelela ezintweni ezisabalalisa imbewu yalezi zitshalo ezizimilelayo. Ucwaningo lungenise indlela ende lusebenzisa izinqolobane zeGoogle Street View ukuhlola izinguquko zemiphakathi yokumilayo futhi lunikela izindlela ezingabizi ukucwaninga ukwehlukahluka kokumilayo kanye nokuphendula kwempilandawonye enguqukweni yezemvelo. Ngokukhomba izimo ezinomthelela ekukhetheni izithelo yizinyoni ezidla izithelo kanye nezinhlobo zezilwane ezincelisayo ezikhona emhlabeni njengazo ezinomthelela ukusabalalisa imbewu, ucwaningo lunikeza isiboniso ekusebenzeni kwesayensi yenhlaliswanobudlelwano eqhuba ukusabalala kwalezi zitshalo ezizimilelayo. Ukuqonda lokhu kwehlukahluka kufundisa ngamasu okungenelela ahlosiwe ukwengamela izitshalo ezizimilelayo, anomthelela emizamweni yokugcinwa komhlaba kanye nokulondolozeka kwezinhlobonhlobo zezinto eziphilayo.