25 research outputs found
Herbaceous perennial plants with short generation time have stronger responses to climate anomalies than those with longer generation time
There is an urgent need to synthesize the state of our knowledge on plant responses to climate. The availability of open-access data provide opportunities to examine quantitative generalizations regarding which biomes and species are most responsive to climate drivers. Here, we synthesize time series of structured population models from 162 populations of 62 plants, mostly herbaceous species from temperate biomes, to link plant population growth rates (λ) to precipitation and temperature drivers. We expect: (1) more pronounced demographic responses to precipitation than temperature, especially in arid biomes; and (2) a higher climate sensitivity in short-lived rather than long-lived species. We find that precipitation anomalies have a nearly three-fold larger effect on λ than temperature. Species with shorter generation time have much stronger absolute responses to climate anomalies. We conclude that key species-level traits can predict plant population responses to climate, and discuss the relevance of this generalization for conservation planning
Plant functional and taxonomic diversity in European grasslands along climatic gradients
Aim: European grassland communities are highly diverse, but patterns and drivers of their continental-scale diversity remain elusive. This study analyses taxonomic and functional richness in European grasslands along continental-scale temperature and precipitation gradients.
Location: Europe.
Methods: We quantified functional and taxonomic richness of 55,748 vegetation plots. Six plant traits, related to resource acquisition and conservation, were analysed to describe plant community functional composition. Using a null-model approach we derived functional richness effect sizes that indicate higher or lower diversity than expected given the taxonomic richness. We assessed the variation in absolute functional and taxonomic richness and in functional richness effect sizes along gradients of minimum temperature, temperature range, annual precipitation, and precipitation seasonality using a multiple general additive modelling approach.
Results: Functional and taxonomic richness was high at intermediate minimum temperatures and wide temperature ranges. Functional and taxonomic richness was low in correspondence with low minimum temperatures or narrow temperature ranges. Functional richness increased and taxonomic richness decreased at higher minimum temperatures and wide annual temperature ranges. Both functional and taxonomic richness decreased with increasing precipitation seasonality and showed a small increase at intermediate annual precipitation. Overall, effect sizes of functional richness were small. However, effect sizes indicated trait divergence at extremely low minimum temperatures and at low annual precipitation with extreme precipitation seasonality.
Conclusions: Functional and taxonomic richness of European grassland communities vary considerably over temperature and precipitation gradients. Overall, they follow similar patterns over the climate gradients, except at high minimum temperatures and wide temperature ranges, where functional richness increases and taxonomic richness decreases. This contrasting pattern may trigger new ideas for studies that target specific hypotheses focused on community assembly processes. And though effect sizes were small, they indicate that it may be important to consider climate seasonality in plant diversity studies
Does “Main Street” Promote Sense of Community? A Comparison of San Francisco Neighborhoods
Neighbourhood in a High Rise, High Density City: Some Observations on Contemporary Hong Kong
Clusters, dispersion and the spaces in between: for an economic geography of the banal
While the geographical clustering of economic activities remains an enduring feature of the industrial landscape and a perennial source of theoretical and empirical interest, the geographical scale at which external economies and agglomerative effects are now claimed to operate is on the increase. Such changes in the spatial form and potential causes of agglomeration over time pose important questions. How should we analyse changes in the spatial extent of external economies and agglomerative effects? Ought we to pay more attention to the sorts of banal economic spaces thrown up as part of increasingly diffuse forms of agglomeration? To answer the first of these questions, it is noted how economists and geographers have explained agglomerations often in the rather singular and invariant categories of pecuniary and Marshallian externalities respectively. This paper considers the relevance of neo-Marshallian analysis and the concept of 'borrowed size'--as variations on these classical principles--to an analysis of the mobility and fixity of external economies and contemporary diffuse forms of agglomeration. Whilst reflecting important changes in the spatial extent of industrial agglomerations, they are insufficiently sensitive to the interaction of different types of external economies with different scale-dependencies. In answering the second question, it is noted that part of the value of analysing the economic basis of largely overlooked 'banal' intermediate places lies in what they may reveal about the functioning of diffuse forms of agglomeration.<br/