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Data on functional traits of flower visitors and plants and on plant-flower visitor interactions across 17 study sites in a South African landscape. Study sites differed in their local degree of natural habitat loss and relative floral abundance of exotic plant species. Functional traits of flower visitors were used to calculate changes in the functional diversity of flower visitor communities with increasing amount of habitat loss and relative abundance of exotic plants.
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When using this data, please cite the following article:
Grass, I., Berens, D. & Farwig, N. (2014): Natural habitat loss and exotic plants reduce the functional diversity of flower visitors in a heterogeneous subtropical landscape. Functional Ecology, in press

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This dataset contains the following tables:

1) Flower visitor list and flower visitor traits
2) Plant list and plant traits
3) Plant-flower visitor interaction networks
4) Environmental data



1) Flower visitor list and flower visitor traits
Contains the mean trait values (in mm) and abundances of the 131 flower visitor species (species and morphospecies) used for analysis in this manuscript. Measured functional traits included proboscis length, proboscis diameter and body length of flower visitors. Traits were measured on up to 12 individuals per species. See Stang, Klinkhamer & van der Meijden (2006) for methods on measurements of flower visitor traits (please note, that in contrast to Stang et al. (2006), we did not measure the length of the hind femure, but of the whole hind leg for the calculation of flower visitor body length). All flower visitors were identified to the lowest taxonomic resolution possible and afterwards sorted into morphospecies (animal code). Flower visitor identification followed  Picker, Griffiths & Weaving (2004), Woodhall (2005) and Scholtz & Holm (2008). The species list is ordered alphabetically by order and family (Col = Coleoptera; Dip = Diptera; Hym = Hymenoptera; Lep = Lepidoptera; NaN = cases in which measurements of specific flower visitor traits were not feasible e.g. because species were damaged; NoIM = number of flower visitor individuals used for measurements; NoRM = number of represented individuals of the respective species among the 17 plant-flower visitor communities). Animal codes are similar to the codes used in a previously published study on the network structure of the plant-flower visitor communities (Grass et al. 2013)

2) Plant list and plant traits
Contains information on the plant species observed for the surveys on plant-flower visitor interactions, as well as information on their origin (native or exotic; NA in exceptional cases where plants were not identified to species level). Also included are raw measurements of floral traits that could affect flower visitor functional diversity. Measured traits (in mm) included nectar holder depth, nectar holder width and size of the alighting place of flowers. See Stang et al. (2006) for definitions and methods on measurements of plant functional traits.

3) Plant-flower visitor interaction networks
Contains the plant-flower visitor interaction networks across the 17 study sites. Information on plant-flower visitor interactions was derived from 80 min timed-observations of plant species. See Grass et al. (2013) for details on observations of plant-flower visitor interactions. Note that this dataset includes all 1470 plant-flower visitor interactions as analysed in Grass et al. (2013), whereas for the analysis of this study only 1434 plant-flower visitor interactions were used. The reduction was necessary to only include plant-flower visitor interactions for which the plant origin was determined (native or exotic) and for which traits of flower visitor species could be measured.

4) Environmental data
Contains information on the amount of natural habitat (generally scarp forest and natural grassland) lost in a 500 m radius surrounding the centre of study sites, as well as information on the relative floral abundance of exotic plants on the total floral abundance of all plant species across study sites. Natural habitat loss was calculated from freely available land cover data (Ezemvelo KZN Wildlife 2011). Relative floral abundance of exotic plants was assessed by repeated standardized transect walks at each study site through the duration of the study. Further given are Universal Transverse Mercator (UTM) coordinates and altitude of study sites, as well as the mean exotic and total floral abundance (measured in floral units [FU]) across transect walks over the course of the study. Numbers of study sites refer to those used for plant-flower visitor interaction networks.



References
Ezemvelo KZN Wildlife. (2011) KwaZulu-Natal Land Cover 2008 V1.1. Unpublished GIS Coverage.
Grass, I., Berens, D.G., Peter, F. & Farwig, N. (2013) Additive effects of exotic plant abundance and land-use intensity on plantpollinator interactions. Oecologia, 173, 913923.
Picker, M., Griffiths, C.L. & Weaving, A. (2004) Field Guide to Insects of South Africa. Struik, Cape Town.
Scholtz, C. & Holm, E. (2008) Insects of Southern Africa. Protea Boekhuis, Pretoria.
Stang, M., Klinkhamer, P.G.L. & van der Meijden, E. (2006) Size constraints and flower abundance determine the number of interactions in a plant-flower visitor web. Oikos, 112, 111121.
Woodhall, S. (2005) Field Guide to Butterflies of South Africa. Struik, Cape Town.


