Search results for "Seed Dispersal"
showing 10 items of 57 documents
The naturalization of the almond Prunus dulcis in different ecological contexts in the Mediterranean: An underestimated process?
2022
Although Prunus dulcis has been frequently listed in non-native floras all around the world, its naturalization has been rarely studied in the field. Probably, because this species has generally invaded synanthropic habitats. We assessed the density of natural regeneration of almond, biometric parameters (height and basal stem diameter), and the distribution in life stage classes in three different ecological contexts in Sicily (Mediterranean Italy): one natural habitat (maquis), one pine afforestation and two prickly pear orchards. We recorded 236 naturally regenerating almond individuals, with density ranging from 140 individuals per hectare (prickly pear orchard 1) up to 2,400 individual…
Plant-animal seed dispersal interactions as key drivers of ecological restoration in a changing world
2022
Many global and European commitments state the need to plant billions of trees and restore millions of hectares of degraded ecosystems to contrast biodiversity loss, desertification and climate change. Seed dispersal is a crucial process promoting vegetation dynamics, and in the Mediterranean, up to 65% of woody plant species need animals for seed dispersal. Therefore, such mutualistic ecological interaction represents a key nature-based solution to help us reaching our commitments. In this presentation first we will report the strong expansion rate and correlated finescale spatio-temporal patterns of woody natural regeneration over a pastureland, using a spatially-explicit framework deploy…
Dryland vegetation pattern dynamics driven by inertial effects and secondary seed dispersal
2022
This manuscript tackles the study of vegetation pattern dynamics driven by inertial effects and secondary seed dispersal. To achieve this goal, an hyperbolic extension of the classical parabolic Klausmeier model of vegetation, generally used to predict the formation of banded vegetation along the slopes of semiarid environments, has been here considered together with an additional advective term mimicking the downslope motion of seeds. Linear stability analyses have been carried out to inspect the dependence of the wave instability locus on the model parameters, with particular emphasis on the role played by inertial time and seed advection speed. Moreover, periodic travelling wave solution…
Food Caching By Willow and Crested Tits: A Test of Scatterhoarding Models
1995
In coniferous forests of Central Finland, Willow (Parus montanus) and Crest- ed Tits (P. cristatus) store seeds in a scattered distribution within their territory during the autumn. Individuals cache and recover food items while moving together as members of mixed-species flocks. The purpose of this study was to test certain predictions of scatter- hoarding models (Stapanian and Smith 1978, Clarkson et al. 1986), which predict how the animal should hoard food items from a superabundant source to maximize the number of caches recovered. Our field experiments gave support to most of the predictions of the models. Individual tits stored seeds closer to the food source when food had been availa…
Density-dependent effect affecting elephant seed-dispersed tree recruitment (Irvingia gabonensis) in Congo Forest.
2012
4 pages; International audience
Introduction et dispersion d'une espèce envahissante : le cas de l'ambroisie à feuilles d'armoise (Ambrosia artemisiifolia L.) en France
2011
National audience; Ambrosia artemisiifolia L. (common ragweed) was accidentally introduced into France in the 1860s. Its single vector of introduction in Europe was red clover seeds (Trifolium pratense L.), probably coming from Pennsylvania, United States at the time. A. artemisiifolia was later introduced into France in many places and at different times. This species has no natural or effective seed dispersal mechanisms and the spread of this weed in the territory is ensured by human activities that carry the seeds and create disturbed environments favourable to its development. It is now established in the Rhone Valley and a number of different factors (cropping system evolution, climate…
Le rôle écologique des bonobos : service écologique de dispersion de graine en forêt du Congo
2012
Bonobos (Pan paniscus) are threatened with extinction. They are the largest primates, and the only apes (except human), of the southern bank of the Congo Basin. Along with chimpanzees, they are our closest living relatives and are studied by anthropologists to include/understand our hominid origins; but what about their functional role in the forest? Would their disappearance have serious consequences for forest ecology? Answering this question is the aim of this new project, with several years of observations of a free-ranging habituated group of bonobos on the LuiKotale research station (DR Congo). In this tropical rainforest, the very great majority of plants need animals to reproduce an…
Correlations among fruit traits and evolution of different fruits within Melastomataceae
2000
Abstract The anatomy and morphology of nearly mature fruits in 85 mainly palaeotropical species of Melastomataceae were examined using microtome- and hand-sectioning, and differential staining. Much structural heterogeneity was observed in both capsules and berries. Multivariate analyses of 31 of the 52 characters recorded for each species, revealed that indehiscence is associated with fusion of ovary and hypanthium tissues, placenta persistence, lack of a persistent endocarp, and a dearth of sclereids in these tissues, while dehiscence is correlated with the opposite states and a persistent exocarp. Other fruit characters such as lignification or fleshiness of tissues do not show a consist…
Seed dormancy and germination of an endangered coastal plantEryngium maritimum(Apiaceae)
2013
INTRODUCTION Eryngium maritimum L. is a littoral species growing on sand dunes and shingle beaches. Although it is listed among the species widespread in western and southern Europe, overall its population is declining (Van der Maarel & Van der Maarel-Versluys, 1996). The species is included in the Red Data Book of Latvia (Fatare, 2003) and is protected in several other European countries. In northern Europe and in the Baltic Region it grows near the limits of its current area of distribution and therefore is at a greater risk of extinction because in small and isolated populations there is a risk of inbreeding depression. For example, in Eryngium alpinum partial self-incompatibility causes…
Seed dispersal, braeding system, tree density and the spatial pattern of trees – a simulation approach
2002
Summary Tropical tree populations with low densities and with clumped spatial distributions are at risk in the face of fragmentation. It is therefore important to understand factors driving spatial patterns of tree populations. An important set of factors which may influence the spatial pattern of plants, could be the spatial distribution of possible seed sources such as the breeding system (monoecious, dioecious), tree density and the spatial pattern of the parent population. Another set of important factors might be dispersal of seeds away from the parent plants characterised by the mean dispersal distance and by the distribution of dispersal distances (either negative exponential or logn…