Summary: 1. It is often assumed that there is a trade‐off between maternal provisioning and dispersal capacity, leading small‐seeded species to disperse further than large‐seeded species. However, this relationship between dispersal distance and seed mass has only been quantified for species from particular sites or with particular dispersal syndromes.2. We provided the first large‐scale, cross‐species quantification of the correlations between dispersal distance and both seed mass and plant height. Seed mass was positively related to mean dispersal distance, with a 100‐fold increase in seed mass being associated with a 4.5‐fold increase in mean dispersal distance (R² = 0.16; n = 210 species; P < 0.001). However, plant height had substantially stronger explanatory power than did seed mass, and we found a 5‐fold increase in height was associated with a 4.6‐fold increase in mean dispersal distance (R² = 0.54; n = 211 species; P < 0.001).3. Once plant height was accounted for, we found that small‐seeded species dispersed further than did large‐seeded species (R² = 0.54; n = 181 species; slope = −0.130; P < 0.001); however, seed mass only added 2% to the R² of the model. Within dispersal syndromes, tall species dispersed further than did short species, while seed mass had little influence on dispersal distance.4. Synthesis. These findings enhance our understanding of plant life‐history strategies and improve our ability to predict which species are best at colonizing new environments.

An understanding of risks to biodiversity is needed for planning action to slow current rates of decline and secure ecosystem services for future human use. Although the IUCN Red List criteria provide an effective assessment protocol for species, a standard global assessment of risks to higher levels of biodiversity is currently limited. In 2008, IUCN initiated development of risk assessment criteria to support a global Red List of ecosystems. We present a new conceptual model for ecosystem risk assessment founded on a synthesis of relevant ecological theories. To support the model, we review key elements of ecosystem definition and introduce the concept of ecosystem collapse, an analogue of species extinction. The model identifies four distributional and functional symptoms of ecosystem risk as a basis for assessment criteria: A) rates of decline in ecosystem distribution; B) restricted distributions with continuing declines or threats; C) rates of environmental (abiotic) degradation; and D) rates of disruption to biotic processes. A fifth criterion, E) quantitative estimates of the risk of ecosystem collapse, enables integrated assessment of multiple processes and provides a conceptual anchor for the other criteria. We present the theoretical rationale for the construction and interpretation of each criterion. The assessment protocol and threat categories mirror those of the IUCN Red List of species. A trial of the protocol on terrestrial, subterranean, freshwater and marine ecosystems from around the world shows that its concepts are workable and its outcomes are robust, that required data are available, and that results are consistent with assessments carried out by local experts and authorities. The new protocol provides a consistent, practical and theoretically grounded framework for establishing a systematic Red List of the world’s ecosystems. This will complement the Red List of species and strengthen global capacity to report on and monitor the status of biodiversity

Barnett, J., L. S. Evans, C. Gross, A. S. Kiem, R. T. Kingsford, J. P. Palutikof, C. M. Pickering, and S. G. Smithers. 2015. From barriers to limits to climate change adaptation: path dependency and the speed of change. Ecology and Society 20(3): 5. https://doi.org/10.5751/ES-07698-200305