Understanding social-ecological regime shifts : the case of woody encroachment in South Africa

Luvuno, Linda (2019-04)

Thesis (PhDAgric)--Stellenbosch University, 2019.

Thesis

ENGLISH ABSTRACT: Humanity has been very successful in modifying the planet to meet the demands of a rapidly growing human population. As human activities have grown in magnitude, they have become increasingly interlinked with ecosystem dynamics, creating social-ecological systems (SES). Increased human impacts on ecosystems are also leading to an increased occurrence of regime shifts: large, persistent changes in the structure and function of ecosystems and SES that often have substantive impacts on the suite of ecosystem services provided by these systems, and on the well-being of people who live in them. As global changes accelerate, better understanding the drivers, impacts and risks of regime shifts has become a key need. This knowledge has important implications for the formulation of management strategies that aim to either maintain existing desirable regimes, restore previous regimes where a regime shift has occurred, or facilitate transformation to new regimes in the novel planetary conditions we face. A prevalent regime shift in savannas worldwide is woody encroachment. Woody encroachment is a shift from a grassy savanna to a persistently woody savanna, and has direct implications for a variety of ecosystem services such as livestock grazing, and people’s livelihoods that depend on these services. Much of the work on woody encroachment has focused on the direct drivers of the process, such as the role of fire or grazing in inhibiting or promoting encroachment. However, less is understood about how underlying social processes may impact these drivers, how ecological changes may feedback to affect some of these underlying social processes, how to monitor woody encroachment as a regime shift and how encroachment impacts ecosystem services and human well-being. This dissertation consists of four research chapters in journal format. The first is a synthesis of the ecological drivers and the social processes and drivers of woody encroachment based on the published literature, synthesized using causal loop diagrams and a published regime shift analysis framework. The remainder of the papers focus on woody encroachment in the Hlabisa district of South Africa. The second paper used Landsat TM imagery to quantify the extent of woody encroachment from 1990 to 2016 under contrasting land uses, specifically state-owned conservation land and communal land largely used for subsistence agriculture. The third paper builds on paper 2 and used spatial autocorrelation and the sequential t-tests analysis for regime shifts (STARS) to explore whether the changes observed in the remote sensing data conform to the statistical properties of a regime shift. The fourth paper used semi-structured interviews to investigate how different land users in the Hlabisa area (state conservation game reserve, private game reserves and local communities) are impacted by woody encroachment. Paper 1 provides a broader social-ecological understanding of woody encroachment. This review highlighted the link between increased human populations (locally and globally) and woody encroachment, and suggests key management options based on the key feedback loops identified. Paper 2 and 3 highlight the value of multi-temporal remote sensing data to monitor the extent of woody encroachment and collect time series data that could be used in the detection of regime shifts and early warning indicator of these shifts. Paper 2 found that Hlabisa experienced significant increases in tree cover between 1990 and 2016, under both the conservation and communal land uses, suggesting that the changes may be largely driven by global drivers rather than local land use practices. Paper 3 shows that these tree cover changes constituted a regime shift, confirmed through the results of STARS and spatial autocorrelation. This paper also suggests that these approaches offer a method that could be used to monitor woody encroachment regime shifts. Paper 4 reveals that all interviewed land users perceived woody encroachment to be increasing in the area. Community members and private game reserve managers mostly reported negative impacts of woody encroachment, with mixed reports from the state reserve managers. This paper also showed that private reserve managers are the most active in undertaking actions to counter encroachment. This research can inform policy and management practices. The dissertation emphasises the importance of understanding the social and ecological interactions that underlie woody encroachment, including the worldviews of land users and managers. With the looming impacts of global warming, and possible technological advances that can change how people live and view the systems in which they live, it is important for SES managers to adopt a complex adaptive systems approach that considers possible feedbacks, drivers at local to global scales, approaching system thresholds, livelihood impacts, as well as the potential for novel planetary conditions.

AFRIKAANSE OPSOMMING: Die mensdom het groot sukses behaal in die verandering van die planeet om aan die eise van 'n vinnig groeiende menslike bevolking te voldoen. Aangesien menslike aktiwiteite in omvang gegroei het, het hul toenemend met die ekosisteem dinamika verband gehou, en sosiaal-ekologiese stelsels (SES) geskep. Verhoogde menslike impak op ekosisteme lei ook tot 'n verhoogde voorkoms van regime verskuiwings: groot, volgehoue veranderinge in die struktuur en funksie van ekosisteme en SES wat dikwels substantiewe impak het op 'n reeks van ekosisteemdienste wat deur hierdie stelsels voorsien word, asook op die welstand van mense wat daarin woon. Soos wêreldwye veranderinge versnel, word die beter begrip vand die druiwers van impakte en risiko's van regime verskuiwings 'n belangrike behoefte. Hierdie kennis het belangrike implikasies vir die formulering van bestuurstrategieë wat daarop gemik is om bestaande gewenste regimes te handhaaf, vorige regimes te herstel waar 'n regime verskuiwing plaasgevind het, of transformasie aan nuwe regimes in die nuwe planetêre toestande wat ons in die gesig staar te fasiliteer. 'n Gewilde regime verskuiwing in savannas wêreldwyd is bos indringing. Bos indringing is 'n verskuiwing van 'n gras savanne na 'n aanhoudende bosagtige savanne en het direkte implikasies vir 'n verskeidenheid ekosisteemdienste soos veeboerdery, en mense se lewensbestaan wat afhanklik is van hierdie dienste. Baie van die bestaande werk op bos indringing fokus op die direkte bestuurders van die proses, soos die rol van vuur of weiding om inbreuk te inhibeer of te bevorder. Minder word egter verstaan oor hoe onderliggende maatskaplike prosesse hierdie bestuurders kan beïnvloed, hoe ekologiese veranderinge terugvoering kan hê om sommige van hierdie onderliggende sosiale prosesse te beïnvloed, hoe om bos indringing as 'n skuifbeweging te monitor en hoe inbreuk op ekosisteemdienste en menslike welsyn impakteer. Hierdie dissertasie bestaan uit vier hoofstukke in joernaal formaat. Die eerste is 'n sintese van die ekologiese druiwers en die sosiale prosesse en druiwers van bos indringing gebaseer op die gepubliseerde literatuur, geskep met behulp van oorsaaklike lusdiagramme en 'n gepubliseerde regime verskuiwing analatiese raamwerk. Die res van die hoofstukke fokus op bos indringing in die Hlabisa-distrik van Suid-Afrika. In die tweede hooftuk word Landsat TM-beelde gebruik om die omvang van bos indringing van 1990 tot 2016 onder kontrasterende grondgebruike te kwantifiseer, spesifiek bewaringsgrond en gemeenskaplike grond wat hoofsaaklik gebruik word vir bestaansboerdery. Die derde hoofstuk bou op hoofstuk 2 en gebruik ruimtelike outokorrelasie en die opeenvolgende t-toetse-analise vir regime-verskuiwings (STARS) om te ondersoek of die veranderinge wat waargeneem word in die afstandwaarnemingsdata ooreenstem met die statistiese eienskappe van 'n regime verskuiwing. In die vierde hoofstuk was semi-gestruktureerde onderhoude gebruik om te ondersoek hoe verskillende grondgebruikers in die Hlabisa-gebied (staatsbehoudreservaat, privaat wildreservate en plaaslike gemeenskappe) deur bos indringing geraak word. Hoofstuk 1 bied 'n breër sosiale-ekologiese begrip van bos indringing. Hierdie oorsig beklemtoon die verband tussen verhoogde menslike bevolkings (plaaslik en globaal) en bos indringing en stel sleutel bestuurs opsies voor wat gebaseer is op die belangrike terugvoerlusse wat geïdentifiseer is. In hooftuk 2 en 3 word die waarde van multi-temporale afstandwaarnemingsdata om die omvang van bos indringing te monitor en die insameling van tydreeksdata vir die opsporing van regime verskuiwings en vroeë waarskuwings tekens van hierdie verskuifings beklemtoom. In hoofstuk 2 is bevind dat Hlabisa tussen 1990 en 2016 beduidende toenames in boombedekking ondervind het, onder beide die bewaring en gemeenskaplike grondgebruike, wat daarop dui dat die veranderinge hoofsaaklik deur globale druiwers gedryf kan word eerder as plaaslike grondgebruikspraktyke. Hoofstuk 3 toon dat hierdie bos indringing 'n regime-verskuiwing was, soos bevestig deur die resultate van STARS en ruimtelike outokorrelasie. Hierdie hoofstuk dui ook daarop dat hierdie benaderings 'n metode bied wat gebruik kan word om bos indringing regime verskuiwings te monitor. Hoofstuk 4 toon aan dat alle ondervraagde landgebruikers waargeneem het dat bos indringing in die gebied verhoog het. Gemeenskapslede en private wildreservaatbestuurders het meestal negatiewe impakte van bos indringing gerapporteer, met gemengde verslae van die staats reservaat bestuurders. In hierdie hoofstuk word ook getoon dat private reserwe bestuurders die mees aktiewe is om aksies te onderneem om indringing teen te gaan. Hierdie navorsing kan beleids- en bestuurspraktyke inlig. Die hoofstuk beklemtoon die belangrikheid van begrip van die sosiale en ekologiese interaksies wat onderliggend in bos indringing is, insluitend die wêreld menings van grondgebruikers en bestuurders. Met die dreigende impak van aardverwarming en moontlike tegnologiese vooruitgang wat kan verander hoe mense leef en die stelsels waarin hulle woon, is dit belangrik vir SES-bestuurders om 'n komplekse aanpasbare stelselsbenadering aan te neem wat moontlike terugvoerings,druiwers op plaaslike tot globale skale, naderende stelsel drempels, lewensgevolge impak, sowel as die potensiaal vir nuwe planetêre toestande in ag te neem.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/105813
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