<I>Eucalyptus</I> invasions in riparian forests: Effects on native vegetation community diversity, stand structure and composition

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Assessing, with limited resources, the ecological outcomes of wetland restoration: a South African case

Resources for evaluating the ecological outcomes of ecosystem restoration projects are often limited, especially within government-funded programs. In order to rapidly assess the ecological outcomes ofwetland restoration, an improved approach has been developed, which was applied in the assessment of the ecological outcomes at nine restoration sites of South Africa’s Working forWetlands program. The sites encompass a diversity of restoration problems and land use contexts. The approach begins by distinguishing hydrogeomorphic (HGM) units, for which ecological condition is assessed and reported for hydrology, geomorphology, and vegetation pre- and post-restoration. These three components are closely linked but, as demonstrated at some of the sites,may respond differentially to restoration interventions. For mostHGMunits, overall ecological condition was improved by between 10 and 30%, with the greatest contribution of restoration generally being to the hydrology component. Having determined the integrity and costs of the interventions, cost-effectiveness is then reported in South African Rands per hectare equivalent restored, which was found to vary by more than an order of magnitude across the HGM units assessed. Cost-effectiveness must be interpreted in the light of the long-term integrity of the interventions, the site’s landscape context, and the contribution of restoration to ecosystem services provision. Some sites may be considerably less cost-effective than others, but the cost may nonetheless be justified if the sites make key contributions to ecosystem services provision. The study was conducted in the context of a formative evaluation and the findings are envisaged to improve wetland restoration practice

Eucalyptus invasions in riparian forests: Effects on native vegetation community diversity, stand structure and composition.

Effects of alien plant invaders on native ecosystems are widely acknowledged, although the evidence is sometimes speculative, especially in riparian zones. We examined the changes in floristic diversity, stand structure and composition of resident species associated with invasions of Eucalyptus camaldulensis in riparian zones of the Western Cape, South Africa. Using a gradient comparative approach, we compared the richness, diversity (H0) and evenness (J) of resident vegetation in a riparian forest under varying levels of E. camaldulensis percentage canopy cover. We found that species richness, diversity and structural attributes (e.g. height, relative cover and mean basal area) of native species decreased consistently along the invasion gradient. However, evenness did not change significantly with increasing Eucalyptus invasion. Invasion by E. camaldulensis was associated with changes in native plant species composition; although some native species occurred in alien invaded sites, they were more abundant in uninvaded sites. This research offers a baseline from which further experimental work can be conducted to determine the mechanisms responsible for changes attributed to Eucalyptus invasion

Eucalyptus invasions in riparian forests: Effects on native vegetation community diversity, stand structure and composition.

Effects of alien plant invaders on native ecosystems are widely acknowledged, although the evidence is sometimes speculative, especially in riparian zones. We examined the changes in floristic diversity, stand structure and composition of resident species associated with invasions of Eucalyptus camaldulensis in riparian zones of the Western Cape, South Africa. Using a gradient comparative approach, we compared the richness, diversity (H0) and evenness (J) of resident vegetation in a riparian forest under varying levels of E. camaldulensis percentage canopy cover. We found that species richness, diversity and structural attributes (e.g. height, relative cover and mean basal area) of native species decreased consistently along the invasion gradient. However, evenness did not change significantly with increasing Eucalyptus invasion. Invasion by E. camaldulensis was associated with changes in native plant species composition; although some native species occurred in alien invaded sites, they were more abundant in uninvaded sites. This research offers a baseline from which further experimental work can be conducted to determine the mechanisms responsible for changes attributed to Eucalyptus invasion

Biological Invasions and Ecological Restoration in South Africa

This chapter provides an overview of the researchers and research initiatives relevant to invasion science in South Africa over the past 130 years, profiling some of the more recent personalities, particularly those who are today regarded as international leaders in the field. A number of key points arise from this review. Since 1913, South Africa has been one of a few countries that have investigated and implemented alien plant biological control on a large scale, and is regarded as a leader in this field. South Africa was also prominent in the conceptualisation and execution of the international SCOPE project on the ecology of biological invasions in the 1980s, during which South African scientists established themselves as valuable contributors to the field. The development of invasion science benefitted from a deliberate strategy to promote multi-organisational, interdisciplinary research in the 1980s. Since 1995, the Working for Water programme has provided funding for research and a host of practical questions that required research solutions. Finally, the establishment of a national centre of excellence with a focus on biological invasions has made a considerable contribution to building human capacity in the field, resulting in advances in all aspects of invasion science—primarily in terms of biology and ecology, but also in history, sociology, economics and management. South Africa has punched well above its weight in developing the field of invasion science, possibly because of the remarkable biodiversity that provided a rich template on which to carry out research, and a small, well-connected research community that was encouraged to operate in a collaborative manner

The forest on the peninsula: impacts, uses and perceptions of a colonial legacy in Cyprus

Throughout history the values and meanings attached to habitats and species in particular places have seen considerable change. Such shifts in perspective are of particular relevance to the biology of invasions, with human attention and values often determining both the initial movement of species around the world, and the decision that subsequent independent spread should be considered damaging to the environment. This chapter examines such a case for the Akrotiri peninsula, Cyprus, where a particular colonial story about the degraded state of the environment, and the need to combat malaria, led to the introduction of various Australian trees for sanitation and other purposes. Today, some of these non-native species are considered invasive, and are having impacts on valued wetland habitats on the peninsula. We use archival research to investigate the changes in policy towards these habitats and the non-native species that affect them, and field research to describe the ecological context. Our study illustrates the complex interactions between ideas, practical aims, and values that lie behind the planned and invaded habitats at Akrotiri