Quantifying Long-Term Urban Grassland Dynamics: Biotic Homogenization and Extinction Debts

Sustainable urban nature conservation calls for a rethinking of conventional approaches. Traditionally, conservationists have not incorporated the history of the landscape in management strategies. This study shows that extant vegetation patterns are correlated to past landscapes indicating potential extinction debts. We calculated urban landscape measures for seven time periods (1938–2019) and correlated it to three vegetation sampling events (1995, 2012, 2019) using GLM models. We also tested whether urban vegetation was homogenizing. Our results indicated that urban vegetation in our study area is not currently homogenizing but that indigenous forb species richness is declining significantly. Furthermore, long-term studies are essential as the time lags identified for different vegetation sampling periods changed as well as the drivers best predicting these changes. Understanding these dynamics are critical to ensuring sustainable conservation of urban vegetation for future citizens

Landscape history, time lags and drivers of change : urban natural grassland remnants in Potchefstroom, South Africa

The history of the landscape directly affects biotic assemblages, resulting in time lags in species response to disturbances. In highly fragmented environments, this phenomenon often causes extinction debts. However, few studies have been carried out in urban settings. To determine if there are time lags in the response of temperate natural grasslands to urbanization. Does it differ for indigenous species and for species indicative of disturbance and between woody and open grasslands? Do these time lags change over time? What are the potential landscape factors driving these changes? What are the corresponding vegetation changes? In 1995 and 2012 vegetation sampling was carried out in 43 urban grassland sites. We calculated six urbanization and landscape measures in a 500 m buffer area surrounding each site for 1938, 1961, 1970, 1994, 1999, 2006, and 2010. We used generalized linear models and model selection to determine which time period best predicted the contemporary species richness patterns. Woody grasslands showed time lags of 20-40 years. Contemporary open grassland communities were, generally, associated with more contemporary landscapes. Altitude and road network density of natural areas were the most frequent predictors of species richness. The importance of the predictors changed between the different models. Species richness, specifically, indigenous herbaceous species, declined from 1995 to 2012. The history of urbanization affects contemporary urban vegetation assemblages. This indicates potential extinction debts, which have important consequences for biodiversity conservation planning and sustainable future scenarios.Peer reviewe

Stakeholder Perceptions of the Ecosystem Services of Health Clinic Gardens in Settlements and Small- to Medium-Sized Cities in the North-West Province, South Africa

Gardens provide spaces for connectedness to nature, which contributes to human well-being and promotes pro-environmental behavior. However, the provision of ecosystem services (ES) in gardens of sub-Saharan Africa is challenged by a lack of knowledge, resulting in inefficient gardening practices. Stakeholders also influence the manifestation of ES provisioning through their perceptions, learning, and decisions. Health clinic gardens may be able to address some of these challenges where other types of gardens fail because of a lack of awareness of other garden benefits and a lack of gardening skills and knowledge, among other factors. Thus, this study aimed to assess stakeholder perceptions of ES provided by health clinic gardens in the North-West province, South Africa. Survey questionnaires were administered to 218 stakeholders across 105 health clinic gardens to ascertain their involvement and prioritization of the ES provided by the gardens and their perspectives on gardens in general. The diversity and abundance of stakeholders per clinic garden were enumerated based on the respondents’ reports. Stakeholder prioritization of ES was scored out of 5, where 1 is the least prioritization. Health clinic gardens have a diversity of one to five types of stakeholders per garden, and more than 80% of the gardens were reported to have a groundsman. Stakeholders spent 1.5 ± 0.5 to 4.7 ± 0.12 days/week engaged in garden activities. Groundsmen spent the most time (4.7 ± 0.12 days/week) in the gardens, while facility managers spent the least (0.90 ± 0.12). Regulating and cultural ES, each scoring an average of 3.7 out of 5, were perceived as the most valuable ES of health clinic gardens. A “garden” was mainly associated with vegetable cultivation and rarely linked with recreation or aesthetical appreciation. A case for establishing these gardens across the country and other developing countries of the Global South can be made through the assessment of their potential ES from the perspectives of stakeholders. This study addresses this topic and contributes to an understanding of the importance of a variety of stakeholders for maintaining functional health clinic gardens

Stakeholder Perceptions of the Ecosystem Services of Health Clinic Gardens in Settlements and Small- to Medium-Sized Cities in the North-West Province, South Africa

Gardens provide spaces for connectedness to nature, which contributes to human well-being and promotes pro-environmental behavior. However, the provision of ecosystem services (ES) in gardens of sub-Saharan Africa is challenged by a lack of knowledge, resulting in inefficient gardening practices. Stakeholders also influence the manifestation of ES provisioning through their perceptions, learning, and decisions. Health clinic gardens may be able to address some of these challenges where other types of gardens fail because of a lack of awareness of other garden benefits and a lack of gardening skills and knowledge, among other factors. Thus, this study aimed to assess stakeholder perceptions of ES provided by health clinic gardens in the North-West province, South Africa. Survey questionnaires were administered to 218 stakeholders across 105 health clinic gardens to ascertain their involvement and prioritization of the ES provided by the gardens and their perspectives on gardens in general. The diversity and abundance of stakeholders per clinic garden were enumerated based on the respondents’ reports. Stakeholder prioritization of ES was scored out of 5, where 1 is the least prioritization. Health clinic gardens have a diversity of one to five types of stakeholders per garden, and more than 80% of the gardens were reported to have a groundsman. Stakeholders spent 1.5 ± 0.5 to 4.7 ± 0.12 days/week engaged in garden activities. Groundsmen spent the most time (4.7 ± 0.12 days/week) in the gardens, while facility managers spent the least (0.90 ± 0.12). Regulating and cultural ES, each scoring an average of 3.7 out of 5, were perceived as the most valuable ES of health clinic gardens. A “garden” was mainly associated with vegetable cultivation and rarely linked with recreation or aesthetical appreciation. A case for establishing these gardens across the country and other developing countries of the Global South can be made through the assessment of their potential ES from the perspectives of stakeholders. This study addresses this topic and contributes to an understanding of the importance of a variety of stakeholders for maintaining functional health clinic gardens

Could Purposefully Engineered Native Grassland Gardens Enhance Urban Insect Biodiversity?

Progress is required in response to how cities can support greater biodiversity. This calls for more research on how landscape designers can actively shape urban ecologies to deliver context-specific empirical bases for green space intervention decisions. Design experiments offer opportunities for implemented projects within real-world settings to serve as learning sites. This paper explores preliminary ecological outcomes from a multidisciplinary team on whether purposefully engineered native grassland gardens provide more habitat functions for insects than mainstream gardens in the City of Tshwane, South Africa. Six different sites were sampled: two recently installed native grassland garden interventions (young native), two contemporary non-native control gardens (young non-native) on the same premises and of the same ages as the interventions, one remnant of a more pristine native grassland reference area (old native), and one long-established, non-native reference garden (old non-native). Plant and insect diversity were sampled over one year. The short-term findings suggest that higher plant beta diversity (species turnover indicating heterogeneity in a site) supports greater insect richness and evenness in richness. Garden size, age, and connectivity were not clear factors mediating urban habitat enhancement. Based on the preliminary results, the researchers recommend high native grassland species composition and diversity, avoiding individual species dominance, but increasing beta diversity and functional types when selecting garden plants for urban insect biodiversity conservation in grassland biomes