Eduardo Brito de Azevedo

Species Distribution Models Do Not Account for Abundance: The Case of Arthropods on Terceira Island

The objective of this study is to investigate whether presence/absence models can be used as surrogates of arthropod abundance, and eventually under which circumstances such surrogacy is guaranteed. Presence/absence data for 48 arthropod species from Terceira Island were modelled using artificial neural networks. Probabilities of occurrence were correlated with abundance data from a standardized arthropod survey programme. Although a tendency was found for vagile species to show relationships, only nine species showed significant positive correlations between probability of presence and abundance. Five of these were exotic spider species with high abundances and wide distributions in several human-modified habitats. The patchy distribution of pristine habitats, the capacity to reach them and the probable low dependence on limiting resources, other than food, enhance the relationship. A lack of significant correlations for the majority of the species may be due to historical events, inappropriate scale, demographic controls of density, or the incapacity of presence/absence models to account for environmental suitability. The difficulty to identify a priori the species for which the relationship will hold advises against the use of species distribution models as surrogates of arthropod abundance.

Spatial Factors Play a Major Role as Determinants of Endemic Ground Beetle Beta Diversity of Madeira Island Laurisilva

The development in recent years of new beta diversity analytical approaches highlighted valuable information on the different processes structuring ecological communities. A crucial development for the understanding of beta diversity patterns was also its differentiation in two components: species turnover and richness differences. In this study, we evaluate beta diversity patterns of ground beetles from 26 sites in Madeira Island distributed throughout Laurisilva – a relict forest restricted to the Macaronesian archipelagos. We assess how the two components of ground beetle beta diversity (βrepl – species turnover and βrich - species richness differences) relate with differences in climate, geography, landscape composition matrix, woody plant species richness and soil characteristics and the relative importance of the effects of these variables at different spatial scales. We sampled 1025 specimens from 31 species, most of which are endemic to Madeira Island. A spatially explicit analysis was used to evaluate the contribution of pure environmental, pure spatial and environmental spatially structured effects on variation in ground beetle species richness and composition. Variation partitioning showed that 31.9% of species turnover (βrepl) and 40.7% of species richness variation (βrich) could be explained by the environmental and spatial variables. However, different environmental variables controlled the two types of beta diversity: βrepl was influenced by climate, disturbance and soil organic matter content whilst βrich was controlled by altitude and slope. Furthermore, spatial variables, represented through Moran’s eigenvector maps, played a significant role in explaining both βrepl and βrich, suggesting that both dispersal ability and Madeira Island complex orography are crucial for the understanding of beta diversity patterns in this group of beetles.

Towards a more holistic research approach to plant conservation: the case of rare plants on oceanic islands

Research dedicated to rare endemic plants is usually focused on one given aspect. However, holistic studies, addressing several key issues, might be more useful, supporting management programs, while unravelling basic knowledge about ecological and population level processes. A more comprehensive approach to research is proposed, encompassing: phylogenetics/systematics, pollination biology and seed dispersal, propagation, population genetics, species distribution models, threats and monitoring. We applied this research approach to Veronica dabneyi, an endangered chamaephyte endemic to the Azores, showing how it could support more effective recovery plans.

Geographical, temporal and environmental determinants of bryophyte species richness in the Macaronesian islands.

Species richness on oceanic islands has been related to a series of ecological factors including island size and isolation (i.e. the Equilibrium Model of Island Biogeography, EMIB), habitat diversity, climate (i.e., temperature and precipitation) and more recently island ontogeny (i.e. the General Dynamic Model of oceanic island biogeography, GDM). Here we evaluate the relationship of these factors with the diversity of bryophytes in the Macaronesian region (Azores, Madeira, Canary Islands and Cape Verde). The predictive power of EMIB, habitat diversity, climate and the GDM on total bryophyte richness, as well as moss and liverwort richness (the two dominant bryophyte groups), was evaluated through ordinary least squares regressions. After choosing the best subset of variables using inference statistics, we used partial regression analyses to identify the independent and shared effects of each model. The variables included within each model were similar for mosses and liverworts, with orographic mist layer being one of the most important predictors of richness. Models combining climate with either the GDM or habitat diversity explained most of richness variation (up to 91%). There was a high portion of shared variance between all pairwise combinations of factors in mosses, while in liverworts around half of the variability in species richness was accounted for exclusively by climate. Our results suggest that the effects of climate and habitat are strong and prevalent in this region, while geographical factors have limited influence on Macaronesian bryophyte diversity. Although climate is of great importance for liverwort richness, in mosses its effect is similar to or, at least, indiscernible from the effect of habitat diversity and, strikingly, the effect of island ontogeny. These results indicate that for highly vagile taxa on oceanic islands, the dispersal process may be less important for successful colonization than the availability of suitable ecological conditions during the establishment phase.

Designing a survey protocol to overcome the Wallacean shortfall: a working guide using bryophyte distribution data on Terceira Island (Azores)

Abstract The increasing availability of open access data on species occurrences is leading researchers to generate more hypotheses about patterns of species distributions. However, when all of this information is mapped onto a particular geographical scale, gaps usually appear due to lack of knowledge and sampling spatial bias (the so-called Wallacean shortfall). To overcome these problems as efficiently as possible, field surveys should be designed after distinguishing well-surveyed places from those with incomplete inventories in order to carry out the extra survey effort in those areas not represented environmentally and spatially by the well-surveyed places. This procedure requires (1) gathering, cleaning and standardizing data; (2) selecting environmental variables that are important for the group considered according to field experience and the literature; and (3) making statistical decisions about the number and location of areas that should be surveyed according to the available resources. Here, we summarize most concepts and procedures devoted to the evaluation of biodiversity data, offering some general recommendations on how to use them for optimizing new survey designs. As a practical guide for potential users, we provide an example describing its application to a comprehensive database on bryophyte distribution on Terceira Island (Azores, Portugal). More than 8,000 bryophyte records were gathered, but (i) less than half of the island area has been surveyed at least once and (ii) less than 1% of these have reliable inventories (placed on the few remnants of laurel forests that have been traditionally better surveyed). Nevertheless, surveying just 15 additional localities evenly distributed across the major environmental regions and habitats on Terceira Island seems to represent the existing environmental diversity. We believe that the survey protocol presented here for bryophytes of Terceira Island could be flexibly applied to other taxa or areas.

Assessing the efficiency of protected areas to represent biodiversity: a small island case study

Protected areas (PAs) have been selected using either subjective or objective criteria applied to an extremely limited subset of biodiversity. Improved availability of species distribution data, better statistical tools to predict species distributions and algorithms to optimize spatial conservation planning allow many impediments to be overcome, particularly on small islands. This study analyses whether 219 species are adequately protected by PAs on Pico Island (the Azores, Portugal), and if they are as efficient as possible, maximizing species protection while minimizing costs. We performed distribution modelling of species’ potential distributions, proposed individual conservation targets (considering the context of each species in the archipelago and their current conservation status) to determine the efficiency of current PAs in meeting such targets and identify alternative or complementary areas relevant for conservation. Results showed that current PAs do not cover all taxa, leaving out important areas for conservation. We demonstrate that by using optimization algorithms it is possible to include most species groups in spatial conservation planning in the Azores with the current resources. With increasing availability of data and methods, this approach could be readily extended to other islands and regions with high endemism levels.

Effects of increasing seawater carbon dioxide concentrations on chain formation of the diatom Asterionellopsis glacialis.

Diatoms can occur as single cells or as chain-forming aggregates. These two strategies affect buoyancy, predator evasion, light absorption and nutrient uptake. Adjacent cells in chains establish connections through various processes that determine strength and flexibility of the bonds, and at distinct cellular locations defining colony structure. Chain length has been found to vary with temperature and nutrient availability as well as being positively correlated with growth rate. However, the potential effect of enhanced carbon dioxide (CO2) concentrations and consequent changes in seawater carbonate chemistry on chain formation is virtually unknown. Here we report on experiments with semi-continuous cultures of the freshly isolated diatom Asterionellopsis glacialis grown under increasing CO2 levels ranging from 320 to 3400 µatm. We show that the number of cells comprising a chain, and therefore chain length, increases with rising CO2 concentrations. We also demonstrate that while cell division rate changes with CO2 concentrations, carbon, nitrogen and phosphorus cellular quotas vary proportionally, evident by unchanged organic matter ratios. Finally, beyond the optimum CO2 concentration for growth, carbon allocation changes from cellular storage to increased exudation of dissolved organic carbon. The observed structural adjustment in colony size could enable growth at high CO2 levels, since longer, spiral-shaped chains are likely to create microclimates with higher pH during the light period. Moreover increased chain length of Asterionellopsis glacialis may influence buoyancy and, consequently, affect competitive fitness as well as sinking rates. This would potentially impact the delicate balance between the microbial loop and export of organic matter, with consequences for atmospheric carbon dioxide.

Nutrient-specific responses of a phytoplankton community: a case study of the North Atlantic Gyre, Azores

 DEPARTAMENTO DE CIÊNCIAS AGRÁRIAS, INSTITUTE OF AGRICULTURAL AND ENVIRONMENTAL RESEARCH AND TECHNOLOGY OF THE AZORES, RUA CAPITÃO D’ÁVILA, SÃO PEDRO, PT-- ANGRA DO HEROÍSMO, AÇORES PORTUGAL, CENTRE FOR COASTAL BIOGEOCHEMISTRY, SCHOOL OF ENVIRONMENT, SCIENCE AND ENGINEERING, SOUTHERN CROSS UNIVERSITY, PO BOX , LISMORE, NSW , AUSTRALIA, DEPARTMENT OF BIOLOGICAL OCEANOGRAPHY, LEIBNIZ INSTITUTE FOR BALTIC SEA RESEARCH, WARNEMÜNDE (IOW), SEESTRASSE , D- ROSTOCK, GERMANY, DEPARTMENT OF BIOLOGICAL OCEANOGRAPHY, OCEANOGRAPHIC INSTITUTE AT THE UNIVERSITY OF SÃO PAULO, PRAÇA DO OCEANOGRÁFICO , SÃO PAULO, SP -, BRAZIL AND

Modelling Native and Invasive Woody Species: A Comparison of ENFA and MaxEnt Applied to the Azorean Forest

Species distribution models are algorithmic tools that relate the distribution and occurrence of a species to the environmental characteristics of the location from where it has been recorded. Those models, also known as ecological niche models, have emerged as an effective tool in spatial ecology, conservation and land management. The Ecological Niche Factor Analysis (ENFA) is one of the common modelling approaches that are suitable for predicting potential distributions, based on presences only, providing an ecological interpretation based on marginality and specialization. In Maximum Entropy Modelling (MaxEnt) the relative entropy is minimized between the two probability densities defined in the covariate space i.e. estimated from presence data or from landscape. It focuses on relating the environmental conditions of the area where the species is present to the environmental conditions across the area of interest. ENFA has been successfully used in the Azores to model the potential distribution of indigenous and non-indigenous trees. In this paper we use distribution data from one of the most important woody plant invaders in the Azores, Pittosporum undulatum, to compare both modelling approaches. We also test both methods when using the selected environmental variables to predict the distribution in other islands and for other species (Acacia melanoxylon and Morella faya). In general, the two methodologies derived similar predictions. However, our results suggest that the set of environmental variables selected to model the distribution of a species in one particular island will probably have to be adjusted to fit other regions and species.

Assessing the landscape functional connectivity using movement maps: a case study with endemic Azorean insects

There is a vast body of literature aiming to predict, for a large number of taxa, the spatial distribution of suitable areas given the expected future changes of climatic conditions. However, such studies often overlook the role of landscape functional connectivity. This is particularly relevant for species with low vagility, as ground-dwelling insects, inhabiting areas with high human pressure due to habitat destruction and fragmentation, namely in the islands. In this study, we developed an individual-based model (IBM) that simulates individual movement according to landscape resistance and mortality probability, in order to derive the landscape movement map, and applied it to five endemic ground-dwelling insects of Terceira Island (Azores). We then confronted the movement maps of each species against the species distribution models previously developed for both current and future climatic conditions, quantifying the amount of important movement areas that are enclosed by the distribution polygons. We further sought to identify where habitat restoration would increase the overall connectivity among large habitat patches. Our results showed that, for both timeframes, the distribution models enclosed small amounts of areas predicted to be important for animal movement. Additionally, we predicted strong reductions (up to 94%) of these important areas for functional connectivity. We also identified areas in-between native forest of primary importance for restoration that may significantly increase the probability of persistence of our model species. We anticipate that this study will be useful to both conservation planners and ecologists seeking to understand species movement and dispersal both is islands and elsewhere.