Ecological features, populations traits and conservation status of Helianthemum caput-felis along its distribution range

Understanding factors limiting populations’ growth and persistence is crucial to evaluate the current conservation status and possible future management of plant populations. This Ph.D. thesis focussed on ecological constraints related to population trends and the conservation status of Helianthemum caput-felis Boiss., characterized by a highly fragmented areal isolated from the distribution centre. In particular, the specifics aims of the thesis were: (1) to analyse the distribution range, population size, the reproductive traits, the effect of human disturbance and identify the threats affecting the persistence of H. caput-felis in Sardinia following the IUCN regional protocol; (2) to investigate flowers and fruits phenology, ecological traits (geomorphology, substrate, slope and human trampling intensity) affecting reproductive outputs (as fruit and seed sets) and the presence of two ecological gradients along the entire European distribution range of the species; (3) to discover the population dynamics by the analyses of populations vital rates, both at global level than a local scale; (4) to evaluate the risk of extinction of H. caput-felis at global level, and then to assess the global conservation status of the populations, together with an accurate analysis of the global area of occupancy of the species, following the IUCN protocol. The thesis results indicate relevant aspect regarding the ecology, population dynamics, distribution and conservation traits of the species. In Sardinia, the species preferably grows in lowland areas with deep structured soil, due to the amount of water and resources available and morphological stability. H. caput-felis shows the highest reproductive output in garrigues, habitat that represents its ecologically optimum. The high seed production indicates that this is not a limiting factor for this plant, in contrast to seedling establishment, which represent its main critical stage. Surprisingly, in Sardinia, human trampling enhanced the plant size and the rate of fruits production, suggesting that reproductive plants of H. caput-felis are tolerant to direct damage, and probably benefit from the reduction of inter-specific and intra-specific competition. Comparing the phenology and reproductive output along the entire European distribution range of this species over a two year temporal context indicate that the general phenological pattern of H. caput-felis was similar among Sardinian and Majorcan regions, whereas, in the eastern Iberian populations (the western part of the distribution range), the southern population (Cabo Roig) showed a higher inter-annual variability and an early flowering period. Those differences could be related to a longitudinal aridity gradient for this plant: the aridity decreases from western to eastern localities. Plants growing at the eastern edge of the distribution range (Sardinia) produce more viable fruits, fruits per plant and seeds per fruit than the other two regions, while plants growing in arid substrate (as in the sandy habitat of Sa Ràpita, Majorca) are the least productive, confirming that sandy substrate is negatively correlated with fruits production and viable fruits, as well as lowland geomorphology. Hence, these analyses underline that the Abundant Centre Model assumptions, by which reproductive traits should be higher at the centre of species distribution, is not confirmed for H. caput-felis, maybe because the central populations, represented by the largest distribution area along the Iberian’s coasts, appear strongly fragmented mainly by human disturbance. Demographic traits of H. caput-felis population were analysed, by using demographic surveys, integrated by Matrix and Integral Projection Models (MPM and IPM, respectively). Plant performance and population dynamics were investigated in plants sampled along the comprehensive and representative part of the European distribution range in which the species occurs. The global population showed a general stability in the first year transition, after which it declined. This trend was probably due to the higher shrinkage of plants in the last year of study, which correlates negatively with reproductive traits, in agreement with the frequent increase in reproductive outputs with plant size. Despite this decline, stochastic population growth rate highlighted as H. caput-felis population oscillated around the equilibrium. Elasticity analysis indicated the higher importance of large individuals and the determinant role of the survival-growth transitions for the population growth rate. Moreover, plants reached high generation times and mean long life span, which, with the limited seedling recruitment rate and the presence of a consistent seed bank, reflect patterns that are typical both of many long-lived plants and of calcareous rupicolous Mediterranean species. IPM methods were found to be more accurate than MPM to monitoring species with restricted range, as H. caput-felis. At local level, the pattern of typical long-lived Mediterranean plants was also confirmed; in fact, populations were mainly composed from large individuals, characterized by slow growth. H. caput-felis showed vital rates and population dynamics varying among populations: the Sardinians’ seems to have greater equilibrium than Spanish populations. The high population growth rates of Moraira and Colònia de Sant Jordi were strongly influenced by the fecundity parameters. Plants growing in Moraira show a uniform shrinkage of individuals, probably due to a more intense fragmentation of the population. The different population dynamics observed among the analysed localities of H. caput-felis should be correlated to particular microclimate and ecological conditions, i.e. the high aridity of Cabo Roig and the sand substrate of Sa Ràpita, which probably affected the relationship among size and vital rates. On the contrary, H. caput-felis populations in demographic equilibrium, as the Sardinians’, could be locally adapted to ecological and microclimate conditions. Finally, population dynamics models were applied to analyse the extinction risk and then assess the global conservation status of H. caput-felis, together with an accurate analysis of the global area of occupancy of the species, following the IUCN protocol. This research highlighted that H. caput-felis should be considered an Endangered (EN) plant at global level, according to the formula B2ab (ii,iii,iv,v) + E. H. caput-felis suffered a continuing decline in AOO, quality of its habitat, number of localities and number of reproductive plants. This decline rate was mainly due to the habitat loss and the expansion of infrastructures detected in the last decades. Hence, effective future conservation measures could be focussed on protecting the single localities where H. caput-felis grows, in order to avoid further species decline. In this contest, conservation efforts primarily aimed to protect established individuals (mature plants) against disturbances, as suggested for other long-lived species. The results of this thesis gave new findings for the ecology and conservation of H. caput-felis, and demonstrate the importance to considerate both global than local level in demography and phenology studies

From global to local scale: where is the best for conservation purpose?

AbstractDemographic analysis of plant populations represents an essential conservation tool allowing to identify the population trends both at global and at the local level. In this study, the population dynamics of Helianthemum caput-felis (Cistaceae) was investigated at the local level by monitoring six populations distributed in Sardinia, Balearic Islands and Ibero-Levantine coast (Alicante). Demographic data for each population were analysed by performing Integral Projection Models (IPMs). Our results showed that, although the local trend of the main basic demographic functions was similar, vital rates and demographic dynamics varied among populations indicating high variability. In fact, asymptotic growth rate in Spanish populations widely varied both between years and populations (some populations growth, decline or strongly decline), while Sardinian populations showed greater equilibrium or a slight increase. Also, the typical pattern of a long-lived species was not supported by the results at the local scale. These results indicated that different populations of the same species can present extremely different population dynamics and support the belief that, for conservation needs, local studies are more informative than global ones: the conservation status of H. caput-felis could notably vary at a small spatial scale and, accordingly, the conservation efforts must be planned at the population level and supported by local analysis

Ecological features, populations traits and conservation status of Helianthemum caput-felis along its distribution range

Understanding factors limiting populations’ growth and persistence is crucial to evaluate the current conservation status and possible future management of plant populations. This Ph.D. thesis focussed on ecological constraints related to population trends and the conservation status of Helianthemum caput-felis Boiss., characterized by a highly fragmented areal isolated from the distribution centre. In particular, the specifics aims of the thesis were: (1) to analyse the distribution range, population size, the reproductive traits, the effect of human disturbance and identify the threats affecting the persistence of H. caput-felis in Sardinia following the IUCN regional protocol; (2) to investigate flowers and fruits phenology, ecological traits (geomorphology, substrate, slope and human trampling intensity) affecting reproductive outputs (as fruit and seed sets) and the presence of two ecological gradients along the entire European distribution range of the species; (3) to discover the population dynamics by the analyses of populations vital rates, both at global level than a local scale; (4) to evaluate the risk of extinction of H. caput-felis at global level, and then to assess the global conservation status of the populations, together with an accurate analysis of the global area of occupancy of the species, following the IUCN protocol. The thesis results indicate relevant aspect regarding the ecology, population dynamics, distribution and conservation traits of the species. In Sardinia, the species preferably grows in lowland areas with deep structured soil, due to the amount of water and resources available and morphological stability. H. caput-felis shows the highest reproductive output in garrigues, habitat that represents its ecologically optimum. The high seed production indicates that this is not a limiting factor for this plant, in contrast to seedling establishment, which represent its main critical stage. Surprisingly, in Sardinia, human trampling enhanced the plant size and the rate of fruits production, suggesting that reproductive plants of H. caput-felis are tolerant to direct damage, and probably benefit from the reduction of inter-specific and intra-specific competition. Comparing the phenology and reproductive output along the entire European distribution range of this species over a two year temporal context indicate that the general phenological pattern of H. caput-felis was similar among Sardinian and Majorcan regions, whereas, in the eastern Iberian populations (the western part of the distribution range), the southern population (Cabo Roig) showed a higher inter-annual variability and an early flowering period. Those differences could be related to a longitudinal aridity gradient for this plant: the aridity decreases from western to eastern localities. Plants growing at the eastern edge of the distribution range (Sardinia) produce more viable fruits, fruits per plant and seeds per fruit than the other two regions, while plants growing in arid substrate (as in the sandy habitat of Sa Ràpita, Majorca) are the least productive, confirming that sandy substrate is negatively correlated with fruits production and viable fruits, as well as lowland geomorphology. Hence, these analyses underline that the Abundant Centre Model assumptions, by which reproductive traits should be higher at the centre of species distribution, is not confirmed for H. caput-felis, maybe because the central populations, represented by the largest distribution area along the Iberian’s coasts, appear strongly fragmented mainly by human disturbance. Demographic traits of H. caput-felis population were analysed, by using demographic surveys, integrated by Matrix and Integral Projection Models (MPM and IPM, respectively). Plant performance and population dynamics were investigated in plants sampled along the comprehensive and representative part of the European distribution range in which the species occurs. The global population showed a general stability in the first year transition, after which it declined. This trend was probably due to the higher shrinkage of plants in the last year of study, which correlates negatively with reproductive traits, in agreement with the frequent increase in reproductive outputs with plant size. Despite this decline, stochastic population growth rate highlighted as H. caput-felis population oscillated around the equilibrium. Elasticity analysis indicated the higher importance of large individuals and the determinant role of the survival-growth transitions for the population growth rate. Moreover, plants reached high generation times and mean long life span, which, with the limited seedling recruitment rate and the presence of a consistent seed bank, reflect patterns that are typical both of many long-lived plants and of calcareous rupicolous Mediterranean species. IPM methods were found to be more accurate than MPM to monitoring species with restricted range, as H. caput-felis. At local level, the pattern of typical long-lived Mediterranean plants was also confirmed; in fact, populations were mainly composed from large individuals, characterized by slow growth. H. caput-felis showed vital rates and population dynamics varying among populations: the Sardinians’ seems to have greater equilibrium than Spanish populations. The high population growth rates of Moraira and Colònia de Sant Jordi were strongly influenced by the fecundity parameters. Plants growing in Moraira show a uniform shrinkage of individuals, probably due to a more intense fragmentation of the population. The different population dynamics observed among the analysed localities of H. caput-felis should be correlated to particular microclimate and ecological conditions, i.e. the high aridity of Cabo Roig and the sand substrate of Sa Ràpita, which probably affected the relationship among size and vital rates. On the contrary, H. caput-felis populations in demographic equilibrium, as the Sardinians’, could be locally adapted to ecological and microclimate conditions. Finally, population dynamics models were applied to analyse the extinction risk and then assess the global conservation status of H. caput-felis, together with an accurate analysis of the global area of occupancy of the species, following the IUCN protocol. This research highlighted that H. caput-felis should be considered an Endangered (EN) plant at global level, according to the formula B2ab (ii,iii,iv,v) + E. H. caput-felis suffered a continuing decline in AOO, quality of its habitat, number of localities and number of reproductive plants. This decline rate was mainly due to the habitat loss and the expansion of infrastructures detected in the last decades. Hence, effective future conservation measures could be focussed on protecting the single localities where H. caput-felis grows, in order to avoid further species decline. In this contest, conservation efforts primarily aimed to protect established individuals (mature plants) against disturbances, as suggested for other long-lived species. The results of this thesis gave new findings for the ecology and conservation of H. caput-felis, and demonstrate the importance to considerate both global than local level in demography and phenology studies

Progetto di un piccolo insediamento a Murano realizzato con tecnologie a basso impatto ambientale

La presente tesi si pone l’obiettivo di indagare le possibilità di applicazione di concetti legati alla sostenibilità ambientale in termini di soluzioni e tecnologie costruttive innovative. In anni di studio nella mia formazione, attraverso molteplici fonti, si sono sedimentati i concetti di “economia circolare”, “bioedilizia”, “riciclo”, “upcycling” (riuso creativo). Sono concetti ormai divenuti un “must” nell’architettura contemporanea che comincia a proporne esempi anche in Italia. A questi concetti mi sono ispirata nel mio progetto, e nelle pagine che seguono cerco di analizzare il concretizzarsi di essi nella pratica delle tecniche di costruzione e nella scelta di produttori e fornitori per il reperimento dei materiali sul mercato, soffermandomi particolarmente su idee guida, normative e certificazioni innovative, progetti modello realizzati. Oggi più che in passato si sente l’esigenza di progettare in maniera attenta tenendo conto di alcuni fattori chiave: la salubrità dei materiali, il reperimento delle risorse e la gestione degli scarti. Assistiamo infatti da un lato alla crescente scarsità di risorse soprattutto in termini di materie prime, con conseguente aumento del costo delle stesse, dall’altro all’ingigantirsi del problema della gestione dei rifiuti. Attualmente in Italia, nonostante la legislazione in materia, la forma più comune di eliminazione dei rifiuti è la discarica. Gli spazi che è possibile destinare alle discariche diventano sempre più esigui; e man mano che la protezione dell’ambiente a livello normativo si fa più stringente i costi legati al conferimento in discarica si fanno più rilevanti. Inoltre, in particolar modo nel caso dei materiali dannosi per l’ambiente, come molti dei rifiuti legati al settore delle costruzioni e demolizioni, lo smaltimento in discarica non rappresenta una soluzione a causa dell’impossibilità in molti casi di ricorrere alla termodistruzione e ai grandi costi relativi all’eliminazione delle sostanze nocive. L’utilizzo del riciclaggio consente quindi di ridurre la massa di rifiuti e di recuperare parte del valore dei materiali. È per questo che già in fase di progetto e produzione molte aziende stanno sviluppando materiali che possano essere riciclati all’infinito e che siano costituiti in tutto o in parte da materie prime seconde. Il futuro del settore delle costruzioni passa quindi per l’innovazione tecnologica e ambientale. Attraverso la chiave della cosiddetta “economia circolare” diventa infatti oggi possibile guardare in modo nuovo al rilancio del settore (anche per farlo uscire da una crisi che va avanti da dieci anni), riducendo l’impatto degli interventi e spingendo il riciclo di materiali. Il dato importante è che non si tratta di sogni ambientalisti ma di prospettive chiaramente scritte nelle direttive europee e realizzate in cantieri di opere pubbliche in Italia e all’estero, che dimostrano la concreta possibilità di ridurre l’impatto sugli ecosistemi e di spingere, al contempo, la creazione di lavoro e di ricerca applicata

Does family of origin make a difference in occupational outcomes?

Disadvantages faced by parent in the labour market. We study the influence of intergenerational transmission of parental socio-economic background on the educational attainment and occupational outcome of children, also considering gender differences. To tackle such a complex system of relationships across the outcome variables (both exogenous and endogenous), we adopt a path analysis model. In particular, we study the intergenerational transmission of disadvantage using the innovative and rich ADSILC database, which shows the evolution of occupational outcomes over eight years (measured by wages in 2011 and 2018). Our findings indicate that being raised in a single-parent family negatively affects wages. Furthermore, high levels of education of at least one parent positively affect children; this effect is especially evident for daughters who grew up with fathers with low education levels

Reproductive performance of Helianthemum caput-felis along its fragmented distribution in the Mediterranean coasts

Plant's reproductive success is determined by intrinsic characteristics of the reproductive system of the species, as well as by extrinsic abiotic and biotic factors. Reproductive traits can vary along different gradients (e.g. ecological, geographical, etc.) and several studies revealed that the most favourable conditions (i.e. greater densities, fitness and genetic diversity) will be found at the core of a plant distribution range than in marginal or isolated populations. In this study the phenological and reproductive traits of several fragmented populations of Helianthemum caput-felis Boiss. (Cistaceae), a perennial Mediterranean plant were investigated. Six populations, covering the entire distribution range of the species were studied over two years (2013–2014). The phenology and reproductive outputs were analysed considering ecological and climatic factors, and human trampling intensity by fitting Generalised Linear Mixed Models (GLMMs). The results indicated that geomorphology, substrate, slope and human trampling intensity affected the reproductive traits of H. caput-felis. An ecological gradient, mainly linked by the interaction of temperature and precipitation regimes could explain this finding. Plants growing at the eastern edge of the distribution range (Sardinia; geographically marginal) produced more fruits than those growing in the other populations. Conversely, plants growing in arid substrate showed a negative correlation with fruit production and viable fruits. The reproductive outputs of the populations located in the core of the distribution range (Cabo Roig and Moraira; ecologically marginal) were lower than those of the other populations. On the other hand an ecological gradient dominated by the precipitation and temperature regimes was detected. In addition, a positive effect of the high and moderate level of human trampling on the reproductive output was found. Further studies, based in particular on the habitat fragmentation, are needed to understand the complex interactions that govern the reproductive output of H. caput-felis in the Mediterranean region

Ecological response to human trampling and conservation status of Helianthemum caput-felis (Cistaceae) at the eastern periphery of its range

Border and isolated plant populations represent an interesting target for ecological and conservation issues. We analysed the ecological constraints and the conservation status of the eastern population of Helianthemum caput-felis Boiss. (Cistaceae), located in Sardinia. The distribution of H. caput-felis was verified via field surveys; ecological data, morphological and reproductive traits, were recorded in 40 permanent plots randomly established; the human trampling effects on plant density, plant size and plant performance were analysed. Plant density was higher in bedrock and lowland areas, in garrigue and maquis habitats; however, the differences among plants growing in different ecological conditions were not statistically significant; only human trampling intensity significantly affected plant density and lowest values were observed in areas with intense trampling pressure. All ecological variables analysed had a statistically significant effect on plant size and on the number of fruits per plant. In particular, larger plants were found in areas with the following ecological features: presence of structured soil, on the slopes, in the maquis habitat, and in areas with intensive human trampling. Conversely, plants displayed a higher fruits output per plant in deep and structured soil, in lowland areas, and in the garrigue and maquis habitats; the mean fruits output per plant increased as human trampling intensified. Human-induced threats are the main hazards threatening the remaining Sardinian population. In particular, the major threats are linked to tourism and other outdoor activities (i.e. human trampling), followed by the expansion of agricultural activities; all of these threats result in the disappearance of small localities and in reduced population size due to habitat loss and fragmentation. Our study indicates that H. caput-felis should be considered as Critically Endangered (CR) at the regional level. Urgent measures should be undertaken to protect the remaining H. caput-felis population in Sardinia and a possible integrated strategy for the conservation and management consists of a combination of in situ and ex situ measures. In particular, greater emphasis should be given to minimizing the negative impacts of unsustainable tourism and recreation use, in order to exclude human trampling and to facilitate the plant recruitment process and population renewal. In addition, an ex situ conservation strategy must be implemented and the seeds collected could be used for future translocations in suitable areas. Moreover, considering the threats observed, a long-term monitoring programme must be developed to reveal changes in the species conservation status

Short-term population dynamics of Helianthemum caput-felis, a perennial Mediterranean coastal plant: a key element for an effective conservation programme

Plant population dynamics is fundamental to identify which parts of the life cycle are important when designing management actions. In this study, the short-term population dynamics of Helianthemum caput-felis (Cistaceae), a perennial plant distributed throughout the western Mediterranean Basin, was investigated by monitoring 98 permanent plots randomly placed along the overall distribution range for three years (2013–2015). Demographic surveys were analysed by Integral Projection Models (IPMs), and the analysis of population growth rates, elasticities, and life table response experiment (LTRE) analyses were performed. Under deterministic conditions, the H. caput-felis population showed a slight increase in the first censuses, but a general population decline followed. This trend was probably due to the shrinkage of plants in the last year, which correlated negatively with reproductive traits. Despite this decline, the population was at equilibrium under the simulated environmental stochasticity. The population dynamics of H. caput-felis followed the general pattern typical for long-lived Mediterranean plants: populations with growth rates closer to the equilibrium in the long term, determinant role of the survival-growth transitions for the population growth rate, slow growth and stasis, longevity of established individuals, shrinkage of medium-large plants, low recruitment rate, high generation times and mean long lifespans. The results of this study, which highlight how conservation measures can be focused on protecting and increasing the number of plants of medium-large size, provide important information for the planning management conservation actions for H. caput-felis and for several Mediterranean plants that show a similar life-history strategy

Does family of origin make a difference in occupational outcomes?

Disadvantages faced by parents adversely affect their children’s chances of success in the labour market. We study the influence of intergenerational transmission of parental socio-economic background on the educational attainment and occupational outcome of children, also considering gender differences. To tackle such a complex system of relationships across the outcome variables (both exogenous and endogenous), we adopt a path analysis model. In particular, we study the intergenerational transmission of disadvantage using the innovative and rich AD SILC database, which shows the evolution of occupational outcomes over eight years (measured by wages in 2011 and 2018). Our findings indicate that being raised in a single-parent family negatively affects men’s education and wages. Furthermore, high levels of education of at least one parent positively affect children; this effect is especially evident for daughters who grew up with fathers with low education levels