Moritz von der Lippe

Human-mediated dispersal of seeds by the airflow of vehicles.

Human-mediated dispersal is known as an important driver of long-distance dispersal for plants but underlying mechanisms have rarely been assessed. Road corridors function as routes of secondary dispersal for many plant species but the extent to which vehicles support this process remains unclear. In this paper we quantify dispersal distances and seed deposition of plant species moved over the ground by the slipstream of passing cars. We exposed marked seeds of four species on a section of road and drove a car along the road at a speed of 48 km/h. By tracking seeds we quantified movement parallel as well as lateral to the road, resulting dispersal kernels, and the effect of repeated vehicle passes. Median distances travelled by seeds along the road were about eight meters for species with wind dispersal morphologies and one meter for species without such adaptations. Airflow created by the car lifted seeds and resulted in longitudinal dispersal. Single seeds reached our maximum measuring distance of 45 m and for some species exceeded distances under primary dispersal. Mathematical models were fit to dispersal kernels. The incremental effect of passing vehicles on longitudinal dispersal decreased with increasing number of passes as seeds accumulated at road verges. We conclude that dispersal by vehicle airflow facilitates seed movement along roads and accumulation of seeds in roadside habitats. Dispersal by vehicle airflow can aid the spread of plant species and thus has wide implications for roadside ecology, invasion biology and nature conservation.

Biological Flora of the British Isles: Ambrosia Artemisiifolia

This account presents information on all aspects of the biology of Ambrosia artemisiifolia L. (Common ragweed) that are relevant to understanding its ecology. The main topics are presented within the standard framework of the Biological Flora of the British Isles: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characters, herbivores and disease, and history, conservation, impacts and management. Ambrosia artemisiifolia is a monoecious, wind-pollinated, annual herb native to North America whose height varies from 10 cm to 2.5 m, according to environmental conditions. It has erect, branched stems and pinnately lobed leaves. Spike-like racemes of male capitula composed of staminate (male) florets terminate the stems, while cyme-like clusters of pistillate (female) florets are arranged in groups in the axils of main and lateral stem leaves. Seeds require prolonged chilling to break dormancy. Following seedling emergence in spring, the rate of vegetative growth depends on temperature, but development occurs over a wide thermal range. In temperate European climates, male and female flowers are produced from summer to early autumn (July to October). Ambrosia artemisiifolia is sensitive to freezing. Late spring frosts kill seedlings and the first autumn frosts terminate the growing season. It has a preference for dry soils of intermediate to rich nutrient level. Ambrosia artemisiifolia was introduced into Europe with seed imports from North America in the 19th century. Since World War II, it has become widespread in temperate regions of Europe and is now abundant in open, disturbed habitats as a ruderal and agricultural weed. Recently, the North American ragweed leaf beetle (Ophraella communa) has been detected in southern Switzerland and northern Italy. This species appears to have the capacity to substantially reduce growth and seed production of A. artemisiifolia. In heavily infested regions of Europe, A. artemisiifolia causes substantial crop-yield losses and its copious, highly allergenic pollen creates considerable public health problems. There is a consensus among models that climate change will allow its northward and uphill spread in Europe.

Plants in Urban Settings: From Patterns to Mechanisms and Ecosystem Services

More than half of the global human population is living in urban areas, and the trend towards further urbanization is strongly increasing (MEA 2005; United Nations 2008). Hence, the majority of people globally will experience “nature” and related ecosystem services primarily within the urban fabric (Gilbert 1989; McKinney 2002; Miller and Hobbs 2002; Miller 2005; Goddard et al. 2010). There is increasing evidence that urban land uses affect profound changes in all environmental components and that humans are the main drivers of change (Sukopp et al. 1979; Pickett et al. 2001; Alberti et al. 2003; Grimm et al. 2008). Urban growth has been identified as a major threat to biodiversity (e.g. Hansen et al. 2005), but at the same time, urban regions can harbour an array of species (Sukopp and Werner 1983; Gilbert 1989; Pys?ek 1993; McKinney 2002) and contribute to the conservation of biodiversity. However, distinct urban ecosystems cannot replace totally the habitat function of (near-)natural systems (Kowarik 2011).

Biological richness of a large urban cemetery in Berlin. Results of a multi-taxon approach.

Abstract Background Urban green spaces can harbor a considerable species richness of plants and animals. A few studies on single species groups indicate important habitat functions of cemeteries, but this land use type is clearly understudied compared to parks. Such data are important as they (i) illustrate habitat functions of a specific, but ubiquitous urban land-use type and (ii) may serve as a basis for management approaches. New information We sampled different groups of plants and animals in the Weißensee Jewish Cemetery in Berlin (WJC) which is one of the largest Jewish cemeteries in Europe. With a total of 608 species of plants and animals, this first multi-taxon survey revealed a considerable biological richness in the WJC. In all, 363 wild-growing vascular plant, 72 lichen and 26 bryophyte taxa were recorded. The sampling also yielded 34 bird and 5 bat species as well as 39 ground beetle, 5 harvestman and 64 spider species. Some species are new records for Berlin.

Sacred sites, biodiversity and urbanization in an Indian megacity

In an era of rapid urban growth, conserving biodiverse urban green spaces is challenging, especially in developing countries. Culturally protected areas including sacred sites are known to contribute to biodiversity conservation in semi-urban and rural areas, but their role in dense urban settings is critically understudied. We, therefore, assessed biodiversity patterns of two types of Hindu places of worship (temples, kattes) and underlying environmental parameters in the Indian megacity of Bengaluru. We analyzed how variables of the urban matrix (age of development, housing density) and type of sacred sites related to biodiversity measures (species abundance, richness, beta diversity), differentiated for cultivated, spontaneous (i.e., wild growing), native and non-native plant species. Native species prevailed in cultivated (66%) and spontaneous (93%) species assemblages, and urbanization parameters significantly related to some biodiversity measures. Beta diversity was highest in sacred sites located in the newest quarters, while abundance of cultivated and non-native species increased with decreasing housing density. Higher richness in low density (i.e., wealthier) quarters demonstrates ‘luxury effect’ for sacred sites. Plots in temples showed higher diversity measures than in kattes, likely due to different management practices. While results demonstrate effects of urbanization on biodiversity measures for temples and kattes, these sites still function as habitats for native species in Bengaluru – and not as foci for invasive alien species as noticed for other urban green spaces. We conclude that urban sacred sites allow people to benefit from multiple ecosystems services and thus play an important role in the urban green infrastructure of quickly growing megacities.