Urban domestic gardens (XII): The richness and composition of the flora in five UK cities

Abstract

Question: What floras are typically associated with domestic gardens in cities? Location: The urban areas of the cities of Belfast, Cardiff, Edinburgh, Leicester and Oxford, UK. Methods: The composition and diversity of plant species in 267 urban domestic gardens in the five cities was recorded by complete census and quadrat sampling. Results: The entire garden flora consisted of 1056 species, of which 30% were native and 70% alien. 34% of the 50 most frequently recorded species in gardens were native, a number of them being weeds. Although plant species richness in individual gardens varied with garden area, the above breakdowns held true when the cities were considered individually. The only exception was Belfast where, overall, plant species richness was slightly lower than in any of the other cities. Comparing quadrat samples, species richness was found to be greater in the garden habitats of each of the cities than in a number of other habitats, with species accumulation curves showing no sign of reaching saturation at 120 quadrats. This is due to the high proportion of alien species found in gardens, and in particular those surviving at low densities as a result of human intervention. Conclusion: There was surprisingly little difference in plant species richness, diversity or composition between the cities, despite the variation in geographical and climatic factors. This suggests that human factors such as plant availability, garden management and social/economic status of individual householders had an overriding influence.

Plant diversity and composition compensate for negative effects of urbanization on foraging bumble bees

“…The higher degree of specialization as found for our bee group-plant network indicates that bumble bees tend to more strongly partition floral resources among each other in Distribution of bumble bees in urban areas urban compared to (semi-)natural landscapes. This behavior might be explained by a generally higher plant diversity in cities compared to the seminatural, often human-influenced landscapes of industrialized countries (Thompson et al 2003;Gaston et al 2005b;Loram et al 2008), which may allow different bumble bee species to more easily distribute themselves across different plant species (see also Miller-Struttmann and Galen 2014) and, in doing so, avoid competition. However, more comparative network analyses are needed in order to confirm this hypothesis.…”

Phylogenetic and functional characteristics of household yard floras and their changes along an urbanization gradient

“…Consequently, lineages specific to yards were also mostly exotic, while lineages specific to Cedar Creek were mostly native to Minnesota (Appendix E). Similarly, Loram et al (2008) found 70% exotic species in the household yard floras of the UK, including both cultivated and spontaneous species. The percenatges of exotics in yards even exceeds the percentage of exotics in complete urban floras (including land areas beyond yards): Pyšek (1998a) showed an average of 40% of exotic plant species for 54 Central European cities; U.S. cities have percentages between 18% and 34% (calculated from species numbers given in Ricotta et al 2009).…”

“…Yards contribute high numbers of species to urban biodiversity (see Gaston et al 2005 and references therein), which can even exceed species numbers of seminatural habitats (Loram et al 2008). They are centers of species cultivation, especially for ornamental species.…”

Food webs: a ladder for picking strawberries or a practical tool for practical problems?

“…While there are no food webs, there are some excellent examples of projects looking at biodiversity in an urban habitat. The Biodiversity in Urban Gardens project run in the city of Sheffield in England made considerable progress studying the diversity of garden plants and insects (Smith et al 2006;Loram et al 2008). Also, driven individuals have listed all the species sampled in a single garden (Owen 1991) or a single town (Price 2002).…”