Geographic consistency in the seed dispersal patterns of Taxus baccata L. in the Iberian Peninsula

Abstract

<p><em>Aim of the study:</em> Seed dispersal is a crucial process in tree population dynamics. In the case of yew, <em>Taxus baccata</em> L., seeds are dispersed by birds and mammals in a non-random, microhabitat-dependent way, a pattern constraining population renewal and expansion. While skewed dispersal has been frequently found, we lack knowledge on how consistent are spatial restrictions across time and yew’s geographical range. This sort of information is required for the development of trans-regional management tools for this species. <em></em></p><p><em>Area of study:</em> Three <em>Taxus baccata</em> stands across Spain, namely Cantabrian Range, Sierra de Gredos and Sierra de Cazorla.<em></em></p><p><em>Material and methods:</em> During two consecutive years, we have been studying the contribution of frugivorous animals to the seed dispersal patterns of <em>Taxus baccata</em> L., in three ecologically contrasted localities of the Iberian Peninsula. <em></em></p><p><em>Main results:</em> The spatial distribution of the seeds in the landscape was very heterogeneous, with the majority of the seeds consistently dispersed into forested microhabitats and almost none outside the forest. The main seed dispersers were always frugivorous birds, particularly thrushes (<em>Turdus merula</em>, <em>T. viscivorus</em>, <em>T. philomelos</em> and <em>T. iliacus</em>). <em></em></p><p><em>Research highlights:</em> The results highlighted the large-scale consistency of the seed dispersal system of <em>Taxus baccata</em>. We suggest that the generalized spatially-restricted dispersal contributes to the lack of regeneration and absence of population expansion of the species all over its range. As a trans-regional conservation strategy, we recommend measures aimed at maintaining as much as diverse assemblage of frugivores in order to provide complementary seed dispersal and therefore enhance population regeneration and expansion.</p><p><strong>Keywords:</strong> English Yew; frugivory; seed rain; microhabitats; <em>Turdus</em> spp.; carnivorous mammals; spatially-restricted dispersal. </p>

How does the functional diversity of frugivorous birds shape the spatial pattern of seed dispersal? A case study in a relict plant species

“…Fruits ripen asynchronously from late summer (August) to late autumn (November), but can remain on trees until late winter when not consumed by seed dispersers [ 19 ]. Yew relies essentially on avian frugivores for seed dispersal, especially on thrushes, Turdus spp., that feed on fruits directly from branches [ 19 , 34 ].…”

“…Nonetheless, we have accounted for this bias by counting some of the predated seeds found in situ as part of the seed rain. Although seed losses might have happened in the rock microhabitat, they were considered negligible (see also [ 34 , 38 , 39 ], for a validation of the methodology).…”

Regeneration of a keystone semiarid shrub over its range in Spain: habitat degradation overrides the positive effects of plant–animal mutualisms

“…; McConkey et al . ; Hayes ; Lavabre & García ). Therefore, analysing the variation in species regeneration and the determinants of such variation at large scales is essential for more adequate management of species and habitats (García et al .…”

Phylogenetics of Taxus Using the Internal Transcribed Spacers of Nuclear Ribosomal DNA and Plastid trnL-F Regions

“…The fruits are eaten by several birds including winter flocking members of the thrush family as well as being hoarded and eaten by rodents [61]. However, Lavabre and García [62] did a study of the seed dispersal patterns of T. baccata across Spain and showed that the spatial distribution of the seeds in the landscape was heterogenous with the majority of the seeds consistently dispersed into forested microhabitats and almost none outside the forest. The results suggest that this generalized spatially restricted dispersal contributes to the lack of population range expansion.…”