BIODIVERSITY RESEARCH Contrasting patterns of turnover between plants, pollinators and their interactions Olivia Norfolk*, Markus P. Eichhorn and Francis S. Gilbert School of Life Sciences, University of Nottingham, University Park, Nottingham, NG7 2RD, UK *Correspondence: Olivia Norfolk, University of Nottingham, University Park, Nottingham NG7 2RD, UK. E-mail: plxon1@nottingham.ac.uk ABSTRACT Aim Biogeographers typically assess patterns of diversity across landscapes. As interacting groups often exhibit contrasting trends, this leads to variation in the structure of interaction networks and thereby influences ecosystem processes. Here we aim to disentangle how patterns of diversity differ between species (plants, pollinators) and their interactions across an agricultural landscape. The region is known for its irrigated gardens which appear as high-diversity islands in the mountainous habitat. We are interested in whether this local enhance- ment was (a) increasing landscape heterogeneity by supporting novel species or (b) increasing local diversity by supporting higher densities of species that also occur in the unmanaged habitat. Location South Sinai, Egypt. Methods We compared alpha diversity of plants, pollinators and interactions in agricultural gardens and plots of unmanaged habitat in two altitudinal cate- gories, high and low mountains, with high and low habitat quality in the matrix respectively. We then used similarity analyses involving the C qN measure to compare levels of turnover across the landscape. Results The impact of the gardens differed with respect to the landscape con- text; in the low mountains, gardens enhanced the abundance and diversity of plants, pollinators and interactions, but in the high mountains, they had no effect. Plants exhibited high levels of turnover, with gardens increasing hetero- geneity by supporting novel crop species. In contrast, pollinators exhibited low levels of turnover, with gardens and unmanaged habitat supporting similar spe- cies. The diversity of interactions was influenced by the composition of the plant community and showed extremely high levels of turnover. Main conclusions Plants, pollinators and their interactions can display con- trasting patterns of turnover across a shared landscape. Although the enhance- ment of local habitat can boost pollinator diversity, the maintenance of habitat heterogeneity may also be required if you aim to conserve the diversity of interactions between plants and pollinators. Keywords beta diversity, desert agriculture, interaction diversity, irrigation, species turnover, visitation network. INTRODUCTION Understanding landscape scale patterns of diversity is an important challenge in conservation biogeography because it can help inform which strategies will be most effective at maximizing diversity. Beta diversity can be maintained across a landscape by two processes, nestedness and spatial turnover (Wright & Reeves, 1992; Baselga, 2010). Nestedness occurs when less diverse assemblages of species form a nested subset of those present in the entire species pool and usually reflects a non-random process of species exclusion from less diverse sites (Ulrich & Gotelli, 2007). In contrast, spatial turnover DOI: 10.1111/ddi.12295 ª 2014 John Wiley & Sons Ltd http://wileyonlinelibrary.com/journal/ddi 1 Diversity and Distributions, (Diversity Distrib.) (2014) 1–11 A Journal of Conservation Biogeography Diversity and Distributions