Phd Thesis Rsbueno.Pdf

1 CO-SUPERVISION AGREEMENT This PhD thesis was developed in co-supervision with Prof. Mauro Galetti, from the Ecology Department of the São Paulo State University UNESP, Brazil, following the agreement established accordingly with the UNESP Resolutions 68/08 and 62/12. Esta tese de doutorado foi realizada em co-orientação com o Prof. Mauro Galetti, do Departamento de Ecologia da Universidade Estadual Paulista UNESP, Brasil, seguindo a convenção de co-tutela estabelecida nos termos das Resoluções UNESP 68/08 e 62/12. Questa tesi di dottorato è stata realizzata in co-tutela con il Prof. Mauro Galetti, del dipartimento di Ecologia della Università Statale Paolista UNESP, Brasile, seguendo la convenzione di co-tutela stabilita nei termini delle Risoluzioni UNESP 68/08 e 62/12. 2 Table of contents General introduction 1 General objective 2 Study site 3 CHAPTER 1 5 Complex spatio-temporal patterns generated in an intense Mediterranean woody secondary succession: the role of past legacies 5 CHAPTER 2 31 Functional complementarity between mammals and birds as seed dispersers in a Mediterranean woodland pasture 31 CHAPTER 3 55 Natural regeneration is more effective than planted trees in concentrating seed rain and promoting recruitment in a dynamic Mediterranean woodland pasture 55 Conclusions 86 Resumo geral em português 87 Acknowledgements 91 3 General introduction GENERAL INTRODUCTION Intensive and extensive human occupation has changed the spatial distribution and composition of the natural vegetation worldwide. However, in recent years, many formerly used lands have been abandoned, reforested, rewilded and again disturbed, creating different templates and trajectories for the evolution of secondary succession. Whether these trajectories will lead to an ecologically restored state, deviate and stabilize in an alternative state or regress to a degraded state are key issues for biodiversity conservation. A starting point to disentangle which factors and mechanisms are leading to these different templates is understand the patterns they generate, in regional, landscape and local spatial scales. In addition, the temporal scale is a very relevant component, many times required, as it will reflect the footprints left by past events, bringing back the history and giving cues to assess the ecological memory and resilience capacity of a determined site. When analyzing how fast and wide the vegetation expanded and how spatially structured this expansion was, a further question that emerge is how sessile plants are able to move, colonize new areas and ultimately generate the observed patterns. Even if some plants can expand through a spatially constrained vegetative growth, most of the pattern is fruit of the seed dispersal. While for example wind, water and gravity are important mechanisms, in Mediterranean up to 65% of the plant species rely on several animal species to complete that task. This wide range of plant-animal interactions will inevitably produce both complementary and redundant contributions in generating that vegetation pattern. Birds and mammals have a pivotal role, although few studies have so far compared simultaneously their seed dispersal services at the same spatio-temporal scale. Due to their intrinsic differences in diet, behavior and habitat use, direct comparisons are required to detect whether they are complementary or redundant in performing the seed dispersal service, as this parameters are expected to vary from one site to another due to the natural context-dependency. Notwithstanding, seed dispersal is not the endpoint explaining the observed spatio-temporal pattern, as once dispersed, seeds still have a long journey towards an effective establishment, facing several abiotic and biotic filters. These filters, especially in areas deprived of vegetation, can completely halt the dispersal template, leading to recruitment limitation. The presence of shrubs and trees scattered in these deforested areas greatly contribute to contrast these limitations, acting as hotspots of seeds and recruitment, also called the perch and nurse effect. But different trees should perform differently this role, especially if varying in their potential to attract seed dispersers or protect the recruits. Moreover, once the recruits evolve, they should also take part on that task, a potential facilitation loop that still has to be better understood. Finally, determine whether passive or active restoration are more effective in promoting ecological restoration is far from straightforward, and this thesis is an attempt to shed some light in this issue, while fulfilling some basic gaps in the knowledge of ecological interactions in the largest Mediterranean island. 1 General objective GENERAL OBJECTIVE The general objective in this thesis was to give both landscape and local scale overview of the patterns and processes behind the woody vegetation dynamics in a gradient forest-woodland pasture considering both passive and active restoration, focusing on a detailed spatio-temporal analysis of the woody vegetation to serve as background to incorporate the role of plant-animal and plant-plant interactions in the vegetation dynamics. To reach this objective the thesis was divided in three chapters. In the first chapter we defined the spatio-temporal template through a detailed investigation of the evolution of the woody vegetation cover along the last 24 years. Combining photointerpretation, field sampling and spatial analysis, we reconstructed the historical background, characterizing and quantifying the woody vegetation changes up to the actual template as well as the effective contribution of natural regeneration, planted trees and past vegetation legacies. In the second chapter we assessed the role of birds and mammals in promoting seed dispersal, the dynamic processes behind plant movement and consequent secondary succession. First we constructed the interaction matrix of birds and mammals with the plants relying on them to have the seeds dispersed, and then we assessed the quantitative and qualitative components of their seed dispersal service, both in the trophic and spatial levels. In the third chapter we assessed the patterns of the first step towards the colonization of the deforested area, the seed rain, and assessed the final critical step, plant establishment, underneath the trees scattered in the pastureland, revealing the spatial structure of their distributions across the study plots as well as comparing whether different types of trees, including natural regeneration and human planted trees, were more effective in generating these patterns. Additionally, beyond the main study of this thesis, I participated in other parallel researches concerning the seed dispersal interactions in urban areas and in agroforestry systems, resulting until now in one published and one submitted work, attached at the end of the thesis. 2 Study site STUDY SITE Our study was conducted inside the “Bosco della Ficuzza, Rocca Busambra, Bosco del Cappelliere e Gorgo del Drago” (hereafter FBCD) natural reserve, a 7.397ha protected area comprising the last large remnant of forest in all western Sicily (Gianguzzi and La Mantia 2004, La Mantia et al. 2010). This reserve has a heterogeneous bioclimatic gradient, from thermo-mediterranean at the lower altitudes (350m a.s.l.) up to supra-meditterranean at the highest elevations (up to 1.613m), with a predominant meso- mediterranean climate (Rivas-Martínez 2008). Inside FBCD, our specific study site was in the Alpe Cucco (37°52' and 13°24'), a woodland pasture of 150 ha surrounded by forest remnants at the center of the Reserve (Figure 1). Alpe Cucco falls in the meso-mediterranean climate, with average rainfall of 850mm and mean annual temperatures of 14.3, with the average temperature of 9.4˚ in the coldest months (January and February) up to an average 23,5 ˚ in the hottest months (July and August). The woody vegetation cover of the forest remnants is characterized mainly by thermophilous evergreen oaks (Quercus ilex and Q. suber), deciduous oaks ( Quercus pubescens ) and to a lesser extent by maple ( Acer campestre) and manna ashes ( Fraxinus ornus ). Hedera helix is also common in the forest. The woodland pasture is composed by a heterogeneous vegetation structure, covered mostly by grasslands, with isolated woody shrubs and trees and varied-sized patches of woody vegetation, composed mostly by fleshy-fruited species (Rosaceae; Pyrus amygdaliformis, Crataegus monogyna, Crataegus laciniata, Rubus ulmifolius, Rosa canina, Prunus spinosa), dry fruited shrubs (Fabaceae; Calicotome infesta, Spartium junceum, Cytisus sp.) . Other fleshy-fruited scrubs or vines, like Asparagus acutifolius , Lonicera sp., Rubia peregrina and Daphne laureola are also present. Around the 1970 and 1980s at Alpe Cucco there was an active reforestation program through the introduction of Fraxinus angustifolia and Pinus halepensis seedlings (Gianguzzi and La Mantia 2004) , two species not occurring naturally there, planted with an irregular pattern at the southern limits of the pasture and practically absent on the northern limit. From the 21 Sicilian non-volant mammals species occurring in the main island just two rodent species ( Glis glis , Muscardinus avellanarius ) are missing at the Ficuzza reserve, while red fox ( Vulpes vulpes ), pine marten ( Martes martes ), weasel ( Mustela nivalis ), wildboar ( Sus scrofa ), fallow deer ( Dama dama ), rabbit ( Oryctolagus cuniculus ), hare ( Lepus corsicanus ), hedgehog ( Erinaceous europaeus

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