Land sharing between cultivated and wild plants: urban gardens as hotspots for plant diversity in cities

Abstract

Plant communities in urban gardens consist of cultivated species, including ornamentals and food crops, and wild growing species. Yet it remains unclear what significance urban gardens have for the plant diversity in cities and how the diversity of cultivated and wild plants depends on the level of urbanization. We sampled plants growing within 18 community gardens in Berlin, Germany to investigate the species diversity of cultivated and wild plants. We tested species diversity in relation to local and landscape-scale imperviousness as a measure of urbanity, and we investigated the relationship between cultivated and wild plant species within the gardens. We found that numbers of wild and cultivated plant species in gardens are high – especially of wild plant species – independent of landscape-scale imperviousness. This suggests that all community gardens, regardless of their urban contexts, can be important habitats for plant diversity along with their role in urban food provision. However, the number of all species was negatively predicted by local garden scale imperviousness, suggesting an opportunity to reduce imperviousness and create more habitats for plants at the garden scale. Finally, we found a positive relationship between the number of cultivated and wild growing species, which emphasizes that community gardens present a unique urban ecosystem where land sharing between cultivated and wild flora can transpire. As the urban agriculture movement is flourishing worldwide with gardens continuously and spontaneously arising and dissipating due to urban densification, such botanical investigations can support the argument that gardens are places for the reconciliation of plant conservation and food production.

Occurrence and diversity of poisonous plants in urban community gardens

“…To obtain a list of plant species present in the gardens, we identified all herbaceous plants to species level using Jäger et al . (2016) and the Pl@ntNet app (CIRAD, INRAE, INRIA, IRD [mobile app], 2013) within eight randomized 1 × 1 m quadrats and within the 20 × 20 m plots along four parallel 5 × 20 m transects (two random plots per transect) ( sensu Seitz et al ., 2022; see for full description of vegetation sampling methods). In addition, in the field, we identified whether the plant species observed was: (i) cultivated (crop, ornamental) or (ii) wild (wild, weed, spontaneous vegetation).…”

“…Urban community gardens are dually important for people to connect to urban biodiversity (Douglas et al ., 2010; Cox et al ., 2018) and for the preservation of urban biodiversity (Lin et al , 2015). Indeed, plant species richness in urban gardens is a collection of both cultivated plants for food and flower production, as well as wild plants that exist spontaneously in the ecosystem to potentially create city hotspot effects (Seitz et al ., 2022). Urban garden plants can provide a range of ecosystem services (Middle et al ., 2014): food plants contribute to food security and sovereignty to support provisioning services (Elmqvist et al ., 2013); decorative plants have aesthetic or religious value to support cultural services (Himes et al , 2020); wild plants and endangered plant species can contribute to biodiversity and nature conservation to provide supporting services (Weiskopf et al ., 2020).…”

Vegetation complexity and nesting resource availability predict bee diversity and functional traits in community gardens

“…To identify vegetation resources for bees, we simultaneously conducted monthly vegetation surveys in the 20 Â 20-m plots to account for variation in vegetation across the sampling season (Seitz et al, 2022). In eight 1 Â 1-m quadrats randomly placed in the 20 Â 20-m plots along four parallel 5 Â 20-m transects (two random plots per transect), all herbaceous plants (except grasses) were identified to species level using Jäger (Jäger et al, 2016) and the Pl@ntNet Handheld Application (https://plantnet.Org/en/).…”

“…Furthermore, urban gardens can support particular wild bee species with different functional traits-including a diversity of pollen collection (and transport) behaviors, nesting behavior, and sociality. These biological characteristics of bee species are highly relevant to efficient pollination services in these gardens, which host a high diversity of food plants and wild plants (Seitz et al, 2022).…”

Bee discovery suggests the importance of urban gardens in a changing world

“…The role of urban habitats such as gardens for supporting species conservation or migration is scarce in evidence though wide in speculation (Hall et al, 2017;Banaszak-Cibicka et al, 2018). Some work has documented how gardens can be hotspots for bee and plant diversity (Baldock et al, 2019), with gardeners cultivating previously undocumented plant species within their yards (Taylor and Mione, 2019;Seitz et al, 2022). Yet we have little evidence of how gardens may provide nectar, pollen and nesting resources for wild bees whose populations may be changing in diversity and distribution under land-use change.…”