Do linear landscape elements in farmland act as biological corridors for pollen dispersal?

Abstract

Summary1. Habitat fragmentation in agricultural landscapes has reduced the population sizes of many plant species while increasing their spatial isolation. Restoration or maintenance of the connectivity by gene flow between the fragmented patches may be determinant to sustaining viable populations, especially for insect-pollinated species. Functional biological corridors facilitating pollen flow between remnants in a human-dominated matrix might achieve this. 2. Dye dispersal was investigated for the extremely fragmented insect-pollinated herb Primula vulgaris, using fluorescent dye particles as pollen analogues, in a study site comprising 20 populations, of which 13 pairs were physically connected by a linear landscape elements (LLEs, ditches), and 11 pairs were not connected by an LLE. The dye deposition events were used to fit a model of pollen dispersal at the landscape level. We examined whether existing LLEs in the intensively used agricultural landscape act as functional corridors for pollen dispersal. The effects of LLE length and size and plant density of the recipient population on the dispersal patterns were tested. 3. Dye dispersal showed a leptokurtic decay distribution, with 80% of the dye transfers occurring at less than 85.1 m, and a maximal distance of 1010.8 m. The mean distance travelled by fluorescent dye particles based on the dye dispersal model was d = 87 m. 4. Dye dispersal between populations was found to be significantly higher when populations were connected by an LLE, than when populations were unconnected. For the group of population pairs connected by an LLE, dye deposition significantly decreased with the distance to dye source, but was not related to recipient population size and plant density. 5. Synthesis. Our study is, to our knowledge, the first to demonstrate that existing LLEs in an intensively used farmland may act as functional biological corridors facilitating pollen dispersal through pollinator movements. The maintenance or restoration of a network of populations connected by LLEs, but also by other landscape structures (e.g. population relays in vegetation patches and networks of small elements allowing indirect connections) should be strongly encouraged.

Managing ditches for agroecological engineering of landscape. A review

“…Moreover, ditch networks are one of the most frequent non-cropped networks in cultivated landscapes, thereby providing a key service of ecological corridors (Herzon and Helenius 2008). These corridors permit the movement of amphibians, mammals, or insects that would otherwise be restricted in hostile and intensively cropped areas (Herzon and Helenius 2008;Van Geert et al 2010). Ditch networks may also connect fractionated populations and favor Ditches and especially vegetated ditches hold inherent pesticide retention power.…”

“…The reduction of the more hydrophobic pesticide loads is generally higher than for the less hydrophobic ones, but this is conditioned by ditch characteristics nd missing data, OC organic carbon their survival and renewal. Indeed, habitat fractionation leads to plant and animal population isolation and threatens plant and animal long-term survival, especially for seed-setting plant species, which require insects for pollination (Van Geert et al 2010). Van Geert and collaborators (2010) found that pollen dispersal was greater when plant populations were connected by ditches.…”

Land management impacts on European butterflies of conservation concern: a review

“…Although quarry operations represent a dramatic land degradation; shortly after their abandonment spontaneous succession turns them into diverse habitat mosaics supporting a rich butterfly fauna (Novák and Konvička 2006;Tropek et al 2010Tropek et al , Č ermáková et al 2010. A similar situation can be observed in other artificial environments especially those created by infrastructure development, such as road margins, railway embankments, gravel pits, or ruderal habitats in suburbia (Van Geert et al 2010;Lenda et al 2012;Moron et al 2014;Nowicki et al 2013). Nevertheless, it must be underlined that such man-made environments offer favourable conditions only in their early successional stages, hence only in the short-term, and later on they require management just like natural habitats in order to prevent overgrowing.…”

Vulnerability of Pollination Ecosystem Services

“…For example, for highly mobile species, the restoration processes can consider creating a 'stepping stone' habitat (e.g., Ottewell et al 2009), whereas dispersal limited species may need more contiguous linear corridors of high-quality habitat (Tewksbury et al 2002) to facilitate movement through inhospitable matrices. In fact, within agricultural settings, plant populations connected by corridors (Townsend and Levey 2005;Van Geert et al 2010) or highly biodiverse matrices (Jha and Dick 2010) have been shown to participate in extensive pollen transfer. Thus, habitat restoration that facilitates pollinator movement has the potential to support improved pollination services across natural and human-altered landscapes, particularly in light of current and plausible future changes in local and regional weather patterns and climate.…”