Pollination biology of the urban populations of an ancient forest, spring ephemeral plant

Maciej A Ziemiański,Marcin Zych

doi:10.5586/asbp.3489

Abstract

Habitat fragmentation, caused by, among all, agriculture and urbanization, is one of the most important drivers of plant biodiversity decline worldwide. One of the signs of deteriorating zoogamous plant reproduction is pollen limitation, often associated with a decline in pollinator diversity and abundance. Various authors predict that the most vulnerable taxa are outbreeding plant species characterized by specialist pollination systems. We have, therefore, focused on self-incompatible Corydalis solida, an ancient forest, spring ephemeral plant, growing in three remnant urban populations in the city of Warsaw (Poland). Over two years, we checked for pollen limitation and recorded insect diversity and abundance for C. solida flowers. Our study populations composed of self-incompatible individuals were mainly visited by generalist pollinators, and produced more seeds when supplementally pollinated. Pollen limitation, however, was greater during 1 year with an early spring onset, when we observed a decline in floral visitors diversity and activity. This was probably an effect of phenological mismatch between plants and their pollinators, in this case, mostly social bees, i.e., over-wintered bumblebee queens and Apis mellifera. We conclude that for outbreeding zoogamous spring ephemerals, such as C. solida serviced by generalist pollinators, changing climatic conditions may override the effects of habitat fragmentation and influence their reproductive success.

Highlights

Habitat fragmentation, caused by, among all, agriculture and urbanization, is one of the most important drivers of plant biodiversity decline worldwide
We investigated three unique natural populations of C. solida located along the Vistula River valley escarpment within the city borders: two occurring in isolated natural forest fragments (Natoliński Forest and Bielański Forest), and the other growing in the arboretum of the Warsaw University Botanic Garden
Since we found no experimental evidence for self-incompatibility in C. solida in the literature, in order to test the breeding system of this species, an additional 30 plants per population were marked and subjected to two further treatments: (C) autonomous self-pollination, and (D) induced geitonogamous pollination

Summary

Introduction

Habitat fragmentation, caused by, among all, agriculture and urbanization, is one of the most important drivers of plant biodiversity decline worldwide. It is estimated that 50% of the global human population live in urbanized areas [1]. Mutualistic interactions may be especially sensitive to the negative effects of fragmentation [4]. One such interaction is the animal-mediated pollination of flowers which, according to various estimates, involves the majority of flowering plants and countless animal (mostly insect) species [5]. Pollen limitation that may be associated with habitat fragmentation [6] and a general decline in pollinator diversity and abundance [7], can negatively affect plant reproductive success and, influence plant population viability [8,9,10,11]

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