New wine and old wineskins? Novel ecosystems and conceptual change

The concept of novel ecosystems (CNE) has been proposed as a way to recognize the extent and value of ecosystems that have been irreversibly transformed by human activity. In this sense, the CNE is realistic about ongoing changes that humans are causing and pragmatic about how to manage them now and in the future. It also provides a dramatic contrast with prevailing conceptions, particularly related to invasive species. Although the CNE has recently been subject to critique, existing critiques do not appear to seriously engage with the extent of anthropogenic change to the world’s ecosystems. Here, I seek to provide a deeper, philosophical and constructive critique, specifically arguing that the usefulness of the CNE is limited in the following three ways: i) it is too static; ii) it is too vague; and iii) it is too dualistic. Although the CNE provides some conceptual advance (‘new wine’), some of its conceptualization and packaging weakly support this advance (‘old wineskins’), so I consider some ways to further develop it, in part to encourage more widespread recognition and appreciation of novel ecosystems

Social-ecological drivers and impacts of invasion-related regime shifts: consequences for ecosystem services and human wellbeing

There are growing concerns that increasing global environmental pressures could lead to the exceedance of critical ecological thresholds that could trigger long-lasting regime shifts that will affect the structure and function of ecosystems and the broader social-ecological systems in which they are embedded. Biological invasions are a major driver of global change, and a number of invasive species alter key ecological feedbacks in ways that lead to regime shifts, with consequences for biodiversity, ecosystem services, livelihoods and human wellbeing. We present four case studies, chosen to represent a diverse range of ecosystems and invasive taxa, to illustrate invasion-driven regime shifts in a variety of social-ecological systems globally. The case studies are: i) wattle trees (Australian Acacia species) in fynbos shrublands in South Africa; ii) Nile perch (Lates niloticus) in Lake Victoria in East Africa; iii) chestnut blight fungus (Cryphonectria parasitica) within broad-leaved forests of eastern North America; and iv) the floating macrophytes salvinia (Salvinia molesta) and water hyacinth (Eichhornia crassipes) in East Sepik Province of Papua New Guinea. For each case we identify the social and ecological drivers and feedbacks underlying the shift, the impacts on ecosystem services and human wellbeing, and the management options for reducing impacts. We discuss the value of using causal-loop diagrams to improve our understanding of the complex dynamics of shifts, and explore how concepts associated with regime shifts can inform guidelines for enhancing adaptive governance of biological invasions. Identifying species that have the potential to generate high-impact regime shifts, understanding the diversity of consequences for different environments and stakeholders, and developing robust management methods to reduce impacts and restore systems to improve social-ecological resilience and reduce vulnerability are priorities for further research

Alien plants as mediators of ecosystem services and disservices in urban systems: a global view

Urban areas have unique assemblages of species which are governed by novel ecological processes. People living in these environments have specific needs and demands in terms of ecosystem services (ES). Urban ecosystems are transformed in many ways by human activities and their floras comprise a high proportion of alien plant species, many of which were intentionally introduced to provide, augment or restore ES. Urban environments also have novel disturbance regimes and provide colonization sites for the establishment, dispersal and proliferation of alien plant species; such conditions often generate biological invasions which may cause marked changes to ES. We review the roles that alien plants play in providing urban ES and ecosystem disservices (EDS) globally. We identify the main ES and EDS associated with alien plants, and highlight the key species involved. A literature search revealed 335 papers, representing studies in 58 cities or urban areas in 27 countries. These studies recorded 337 alien plant species, contributing to 39 different ES and 27 EDS–310 species were recorded as contributing to ES and 53 species to EDS. A small number of alien plant taxa were frequently recorded as providing multiple ES in many urban ecosystems; the 10 most recorded species accounted for 21% of the ES recorded. Some of these species also result in significant EDS; three species accounted for 30% of the EDS recorded. Cultural services (notably aesthetics) are the most reported ES provided by alien plants in urban areas of developed countries, while provisioning services (notably food production) are most reported in developing countries. The most commonly studied EDS provided by alien plants is the impact on human health (notably allergic reactions). Eighty percent of studies on alien plants and ES and EDS have been done in developed countries. To elucidate the full range of effects of alien plants, more work is needed in developing countries. Urban planners and managers need to be mindful of both the positive and negative impacts of alien plant species to maximise the provision of ES

Pollination of two species of Vellozia (Velloziaceae) from high-altitude quartzitic grasslands, Brazil Polinização de duas espécies de Vellozia (Velloziaceae) de campos quartzíticos de altitude, Brasil

The pollinators and breeding system of two species of Vellozia (Velloziaceae) from high-altitude quartzitic grasslands in SE Brazil were studied. Vellozia leptopetala is shrubby and grows solely on rocky outcrops, V. epidendroides is herbaceous and grows on stony soils. Both bear solitary, hermaphrodite flowers, and have massive, short-lasting annual blooms. We evaluated the level of self-compatibility and need for pollinators of 50 plants of each species and 20-60 flowers per treatment: hand self- and cross-pollination, spontaneous pollination, agamospermy and control. The behavior of floral visitors on flowers and within plants was recorded. Both species are mostly self-incompatible, but produce a small number of seeds by self-fertilization. The pollen-ovule ratio suggests facultative xenogamy. They were visited primarily by bees, of which the most important pollinators were two leaf-cutting bees (Megachile spp.). Vellozia leptopetala was also pollinated by a territorial hummingbird. Low natural seed production compared to cross-pollination seed numbers suggests that pollen limitation is the main cause of low seed set. This was attributed to the combined effect of five mechanisms: selfing prior to anthesis, enhanced geitonogamy as a result of large floral displays, low number of visits per flower for the same reason, pollen theft by many insect species, and, in V. leptopetala, delivery of mixed pollen loads on the stigma as a consequence of hummingbird promiscuity.<br>Foram pesquisados os polinizadores e o sistema reprodutivo de duas espécies de Vellozia (Velloziaceae) de campos rupestres quartzíticos do sudeste do Brasil. Vellozia leptopetala é arborescente e cresce exclusivamente sobre afloramentos rochosos, V. epidendroides é de porte herbáceo e espalha-se sobre solo pedregoso. Ambas têm flores hermafroditas e solitárias, e floradas curtas em massa. Avaliou-se o nível de auto-compatibilidade e a necessidade de polinizadores, em 50 plantas de cada espécie e 20-60 flores por tratamento: polinização manual cruzada e autopolinização, polinização espontânea, agamospermia e controle. O comportamento dos visitantes florais nas flores e nas plantas foi registrado. As espécies são auto-incompatíveis, mas produzem poucas sementes autogâmicas. A razão pólen-óvulo sugere xenogamia facultativa em ambas. Foram visitadas principalmente por abelhas, das quais as mais importantes polinizadoras foram duas cortadeiras (Megachile spp.). Vellozia leptopetala também foi polinizada por uma espécie de beija-flor territorial. A produção de sementes em frutos de polinização cruzada sugere que limitação por pólen é a causa principal da baixa produção natural de sementes. Isto foi atribuído ao efeito combinado de cinco mecanismos: autopolinização prévia à antese, elevada geitonogamia resultante de arranjo floral, número reduzido de visitas por flor pelo mesmo motivo, pilhagem de pólen por diversas espécies de insetos e, em V. leptopetala, deposição de pólen heteroespecífico em conseqüência da promiscuidade dos beija-flores