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Soares Gomes Cardosos de Oliveira, Maria Alexandra
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- Measuring and mapping the effectiveness of the European Air Quality Directive in reducing N and S deposition at the ecosystem levelPublication . Serrano, Helena Cristina; Oliveira, Maria Alexandra; Barros, Ceres; Augusto, Ana Sofia; Pereira, Maria João; Pinho, Pedro; Branquinho, CristinaTo protect human health and the environment (namely ecosystems), international air quality protocols and guidelines, like the Gothenburg protocol (1999) and the 2001 EU Air Quality Directive (NECD), conveyed national emission ceilings for atmospheric pollutants (Directive 2001/81/EC), including the reduction of sulfur (S) and nitrogen (N) emissions by 2010. However, to what degree this expected reduction in emissions had reflections at the ecosystem level (i.e. pollutant levels reaching and impacting ecosystems and their organisms) remains unknown. Here, we used lichens as ecological indicators, together with reported air and precipitation pollutant concentrations, to determine and map the consequences of the S and N atmospheric emission's reduction, during the implementation of the 2001 Directive (in 2002 and 2011), due primarily to the industrial-sector. The study area is a mixed-land-use industrialized Mediterranean agroforest ecosystem, in southwest Europe. The reduction of S emissions (2002−2011) was reflected at the ecosystem level, as the same S-declining trend was observed in atmospheric measurement stations and lichens alike (−70%), indicating that most S deposited to the ecosystem had an industrial origin. However, this was not the case for N with a slight N-reduction near industrial facilities, but mostly N-deposition in lichens increased in areas dominated by agricultural land-uses. Taken together, these results highlight the importance of going beyond emissions estimation and modeling, to assess the success of the implementation of the NECD in lowering pollutant accumulation in living organisms and their environment. This can only be achieved by measuring pollutant deposition at the ecosystem level (e.g. living organisms). By doing so, we were able to show that the 2001 NECD was successful in reducing S concentrations from Industry, whereas N remains a challenge. Despite the small reduction in N-emissions, deposition into ecosystems did not reflect these changes as agriculture and transport sectors must reduce NH3 and NOx emissions.
- Estimating the age and mechanism of boulder transport related with extreme waves using lichenometryPublication . Oliveira, Maria Alexandra; Llop, Esteve; Andrade, C.; Branquinho, Cristina; Goble, Ronald; Queiroz, Sónia; Freitas, Maria da Conceição; Pinho, PedroTsunamis and storms cause considerable coastal flooding, numerous fatalities, destruction of structures, and erosion. The characterization of energy and frequency associated with each wave contribute to the risk assessment in coastal regions. Coastal boulder deposits represent a physical proof of extreme inundation and allow us to study the effects of marine floods further back in time than instrumental and historical records. Age estimation of these deposits is challenging due to lack of materials (such as sand, shells, corals, or organic matter) that retain information about the passage of time. Lichenometry, a simple age estimation method, which is cost-effective, quick to apply, and non-destructive, is here proposed as a solution. A lichen growth model for a calcium-tolerant lichen species was developed and used to estimate the age of a boulder deposit related to extreme marine inundation(s) in Portugal. Estimated ages indicate several very recent events (<700 years) for most of the boulders’ stabilization and agree with results obtained with optically stimulated luminescence of marine sands found beneath boulders. Frequent and recent boulder transport implies a storm-origin for this deposit. These conclusions contrast with other works describing identical deposits that are attributed to paleotsunamis. This study presents a methodology using lichenometry as a successful alternative for age estimation in rocky coastal settings. These results offer an alternative explanation for coastal boulder deposits found on the west coast of Portugal.
- How Do Taxonomic and Functional Diversity Metrics Change Along an Aridity Gradient in a Tropical Dry Forest?Publication . Oliveira, Ana; Nunes, Alice; Oliveira, Maria Alexandra; Rodrigues, Renato Garcia; Branquinho, CristinaEcological indicators based on biodiversity metrics are valuable and cost-effective tools to quantify, track and understand the effects of climate change on ecosystems. Studying changes in these indicators along climatic gradients in space is a common approach to infer about potential impacts of climate change over time, overcoming the limitations of lack of sufficiently long time-series data. Here, we studied the response of complementary biodiversity metrics in plants: taxonomic diversity (species richness and Simpson index) and functional diversity (diversity and redundancy) in 113 sampling sites along a spatial aridity gradient (from 0.27 to 0.69 of aridity index-AI) of 700 km in a Tropical dry forest. We found different responses of taxonomic and functional diversity metrics to aridity. Species diversity showed a hump-shaped curve peaking at intermediate levels of aridity between 0.38 and 0.52 AI as an ecotone, probably because it is where most species, from both drier and more mesic environments, still find conditions to co-exist. Functional diversity showed a positive linear relation with increasing aridity, suggesting higher aridity favors drought-adapted species with diverse functional traits. In contrast, redundancy showed a negative linear relation with increasing aridity, indicating that drier sites have few species sharing the same functional traits and resource acquisition strategies. Thus, despite the increase in functional diversity toward drier sites, these communities are less resilient since they are composed of a small number of plant species with unique functions, increasing the chances that the loss of one of such "key species" could lead to the loss of key ecosystem functions. These findings show that the integration of complementary taxonomic and functional diversity metrics, beyond the individual response of each one, is essential for reliably tracking the impacts of climate change on ecosystems. This work also provides support to the use of these biodiversity metrics as ecological indicators of the potential impact of climate change on drylands over time.
- Boulder deposits related to extreme marine events in the western coast of PortugalPublication . Oliveira, Maria Alexandra; Andrade, César Freire de, 1955-; Neves, Ramiro Joaquim Jesus, 1955-This work describes a complex boulder accumulation found in the Portuguese western coastline, N of Ericeira, containing over 1600 boulders sitting on a structural platform and low cliffs at 2-13 m above mean sea level (amsl). The main objective of this work consisted in the identification (storm vs tsunami), age estimation and the computation of recurrence intervals of extreme events responsible for the transport and deposition of this boulder accumulation. Several proxies were used to interpret the origin of the deposit under analysis, such as: morphological characteristics of the boulder accumulation and of individual boulder positions and arrangement; monitoring boulder movement by storms, numerical modelling of storm wave propagation and with statistical analysis of extreme values applied to the wave regime; application of numerical approximations describing boulder movement; age estimation based on aerial photographs, lichenometry, erosion rates and optically stimulated luminesce (OSL) of finer sediments of marine origin. Distribution of source layer, mass and directional properties indicate short-lived boulder transport following a flow directed from the W-NW, compatible with the modern-day wave regime rather than the major tsunamigenic source, located SW of Portugal. Statistical modelling of extreme values applied to the wave regime and comparison with storm wave parameters which generated observed boulder movement, indicate 2-5-years recurrence interval for the occurrence of storms capable to generate boulder transport and deposition in the W-NW facing segments, and a higher than 20 years in the WSW-facing segments of the study area. Moreover, the application of numerical solutions to the boulder dataset indicate wave periods and significant wave heights compatible with a storm origin and with the wave regime affecting the western Portuguese coastline. A strong geomorphological signature is observed in the morphological characteristics of the boulder accumulations. This is reflected in local changes of directional properties of boulders which mimic the coastline configuration, with emphasis in areas of the structural platforms where NW-SE aligned indentations exist. These indentations function as natural channels and generate a funnelling effect increasing the potential to detach and transport boulder-size particles. Age estimation results based on the comparison of aerial photographs and lichenometry indicate that boulder transport frequently occurs, thus implying a storm origin to at least part of the deposit. Additionally, it indicates an extremely recent age for the boulder accumulation from around the 14th-15th centuries. Moreover, age estimation results obtained for lichenometry show that this boulder accumulation mainly comprises boulders recently deposited (past ~140 years), which is confirmed with results from OSL age estimation of marine sand patches found within a boulder cluster, of 230-290 years. The fact that older boulders are scarce and that boulder transport and deposition frequently occurs suggests that: the boulder deposit under analysis is highly dynamic and that particles typically present a residence period lower than 200 years; the AD 1755 tsunami, which reached a minimum height of 9 m amsl, partly obliterated a previously existing boulder accumulation, having mostly generated an essentially erosive signature. The presence of older and sometimes heavier boulders located higher up and further inland in WSW facing segments of the coastline indicates boulder deposition on these locations during higher storminess periods, probably associated with periods of negative NAO index. This work contributes to the discussion regarding sedimentological/erosional signatures of boulder-size accumulations associated with storms and tsunamis in rocky coastlines and to a better understanding of the geomorphological controls and physical processes occurring within this context. Another relevant contribution was the development of a lichen growth model for the species Opegrapha durieui Mont. (Roux and Egea, 1992), which allows estimating the age of limestone surface exposure of up to ~500 years.
- Shifts in plant functional groups along an aridity gradient in a tropical dry forestPublication . de Oliveira, Ana Cláudia Pereira; Nunes, Alice; Oliveira, Maria Alexandra; Oliveira, Rafael S.; Rodrigues, Renato Garcia; Branquinho, CristinaIncreasing aridity associated with climate change may lead to the crossing of critical ecosystem thresholds in drylands, compromising ecosystem services for millions of people. In this context, finding tools to detect at early stages the effects of increasing aridity on ecosystems is extremely urgent to avoid irreversible damage. Here, we assess shifts in plant community functional structure along a spatial aridity gradient in tropical dryland (Brazilian Caatinga), to select the most appropriate plant functional groups as ecological indicators likely useful to predict temporal ecosystem trajectories in response to aridity. We identified seven plant functional groups based on 13 functional traits associated with plant establishment, defense, regeneration, and dispersal, whose relative abundances changed, linearly and non-linearly, with increasing aridity, showing either increasing or decreasing trends. Of particular importance is the increase in abundance of plants with high chemical defense and Crassulacean Acid Metabolism (CAM) photosynthetic pathway, with increasing aridity. We propose the use of these functional groups as early warning indicators to detect aridity impacts on these dryland ecosystems and shifts in ecosystem functioning. This information can also be used in the elaboration of mitigation and ecological restoration measures to prevent and revert current and future climate change impacts on tropical dry forests.
- Do Mesocarnivores Respond to the Seasonality in Management Practices in an Agroforestry Landscape?Publication . Barros, Ana Luisa; Raposo, Diogo; Almeida, João David; Alcobia, Sandra; Oliveira, Maria Alexandra; MacKenzie, Darryl I.; Santos-Reis, MargaridaIn the Mediterranean, we find a mosaic of natural and cultural landscapes, where a variety of forest management practices created intermediate disturbance regimes that potentially increased biodiversity values. Nonetheless, it is essential to understand the species’ long-term response to the dynamic management in agroecosystems, since the species tolerance to disturbance can change throughout the life cycle. Mammalian carnivores can be sensitive to human disturbance and are an essential part of ecosystems due to their regulatory and community structuring effects. We investigated the spatial response of five mesocarnivores species to spatially- and temporally- varying management practices in an agroforestry landscape. More specifically, we assessed the mesocarnivores’ temporal changes in space use by implementing multi-season occupancy models in a Bayesian framework, using seasonal camera-trapping surveys for a 2-year period. All species had a weak response of local extinction to forestry management and livestock grazing pressure. For forest-dwelling species, occupancy was higher where productivity of perennial vegetation was high, while colonization between seasons was positively associated with vegetation cover. For habitat generalist species, we found that occupancy in the wet season increased with the distance to cattle exclusion plots. Most of these plots are pine stands which are subject to forestry interventions during winter. During the 2-year period we found seasonal fluctuations in occupancy for all species, with an overall slight decrease for three mesocarnivore species, while for the two forest-dwelling species there was an increase in occupancy between years. The weak species response to management practices supports the importance of traditional management for upholding a diverse mesocarnivore community in agroforestry systems but could also reflect these species’ ecological plasticity and resilience to disturbance.
- Morphological controls and statistical modelling of boulder transport by extreme stormsPublication . Oliveira, Maria Alexandra; Scotto, Manuel; Barbosa, Susana; Andrade, C.; Freitas, Maria Da ConceiçãoThe study of coastal boulder accumulations generated by extreme marine events, and of the energy and frequency involved in boulder transport, is of paramount importance in understanding the risk associated with extreme marine inundations. One of the frequently asked questions is whether the deposits are storm or tsunami-related, both events being characterized by different return periods. Boulder transport by storms was monitored on the west coast of Portugal. Significant changes were detected in boulders' position as a result of extreme inundation by the 2013/2014 winter storms. Results presented in this work indicate that the wave power associated with the “Christina” and “Nadja” storms occur once every three years. However, this interval is not supported by field observations of boulder displacement, which suggests that wave power over-predicts boulder movement in the study area. Furthermore, wave parameters from the “Christina” and “Nadja” storms were very similar, but have generated different impacts in the boulder accumulation described herein. Differences include the magnitude and direction of boulder movement, and are most likely associated with distinct tidal levels during the events. Higher tide levels generated an increase in the sea surface level and thus in the reach of waves, which generated displacement of larger boulders and consequent cross-shore contribution in boulder transport. Regardless, the combination of monitoring campaigns, wave data, and statistical modelling of extreme values indicate that boulder transport by storms is more frequent than initially expected. Based on recorded boulder movements, we present a conceptual model for boulder ridge formation and development and identify significant control of incoming flow by local geomorphological/topographical features. Storm events, not less frequent tsunamis, are identified as the events responsible for modulating this rocky coastline. These results question a direct attribution of coastal boulder deposits to tsunamis in coastal regions with a high risk of tsunami inundation.
- An integrated assessment of niche partitioning reveals mechanisms of coexistence between mesocarnivoresPublication . Barros, Ana Luisa; Raposo, Diogo; Almeida, João David; Jesus, Hugo; Oliveira, Maria Alexandra; FERNANDES, CARLOS; MacKenzie, Darryl I.; Santos-Reis, MargaridaSpecies diversity depends on the capacity of species to coexist, and when these share similar ecological requirements some degree of partitioning of the ecological niche is expected. Within the order Carnivora, direct and indirect interspecific interactions shape community structure and composition. Although strong negative interactions (e.g., interspecific killing) are expected between large carnivores and subordinate species, mesocarnivores that dominate most human disturbed landscapes can still strongly compete for resources given their similar body size and energy requirements. To identify the mechanisms of coexistence between mesocarnivore species in a Mediterranean landscape we assessed the ecological niche overlap between five species (Vulpes vulpes, Meles meles, Martes foina, Herpestes ichneumon, Genetta genetta), by simultaneously measuring the space, time, and trophic resource use. The multi-species occupancy model fit to camera-trapping data revealed spatial co-occurrence between most species’ pairs and an avoidance pattern between only stone marten and Eurasian badger (78 % probability of a negative effect). Using genetically identified scats, we assessed trophic niche breadth and overlap. Niche breadth was narrow for red fox, Eurasian badger, and stone marten, given these species consumed almost exclusively fruits and arthropods, and so trophic niche overlap was high. For the genet and the mongoose, the consumption of different food resources (e.g., mammals, birds, and reptiles) increased niche breadth and decreased the niche overlap with the other sympatric species. Finally, niche segregation was more significant along the temporal axis, since the mongoose has a diurnal activity pattern and the remaining carnivore species, although mostly nocturnal, had small asynchronies in the activity peaks which could decrease the chance of direct encounters. Therefore, our results suggest that similar habitat preferences and ecological requirements rather than interspecific competition shape the mesocarnivores’ resource use in this landscape. Nonetheless, fine-scale temporal segregation seems the main mechanism to facilitate coexistence, together with small differences in trophic resource use, especially for species with high spatial and temporal overlap.
- Nitrogen and sulfur deposition over a region in SW Europe based on a regional atmospheric chemical transport modelPublication . Oliveira, Maria Alexandra; Tomlinson, S.J.; Carnell, E.J.; Dore, A.J.; Serrano, H C; Vieno, M.; Cordovil, C.M.d.S.; Dragosits, U.; Sutton, M.A.; Branquinho, Cristina; Pinho, PedroAir quality affects both ecosystems and human health. To assess the effects of air pollution, spatially explicit information of pollutants is needed. Atmospheric chemistry transport models are the best option to estimate concentrations and deposition of pollutants, from local to regional scales. However, concentration and deposition maps derived from available regional and global models are typically given at spatial resolutions of 10–50 km and do not contain information at sufficiently high spatial resolution (i.e. ≤ 5 km × 5 km) to identify risks and to develop solutions to protect the ecosystems and human health. Here, we provide deposition and concentration of nitrogen (N) and sulfur (S) at a 5 km × 5 km resolution for the western Iberian Peninsula. The new maps are a major improvement over existing information due to the higher spatial resolution. Comparison with measurements indicates that all maps for N compounds are fit for purpose. Nitrogen deposition in W Iberia ranged from 3 to 38.6 kg N·ha−1·year−1, averaging 8.2 kg N·ha−1·year−1 with a higher contribution from reduced N forms (62%). Deposition of oxidized forms mainly prevailed in urban and industrial areas and in coastal locations. The contribution of wet deposition was slightly higher (55%) than dry deposition and more important in the North, following the pattern of precipitation. Dry deposition is higher closer to emission sources. Due to their high spatial resolution, these maps can be used for policy development to support ecosystem protection, through the identification of areas at greater risk due to high N deposition. National policy efforts to reduce N pollution must, foremost, target ammonia (NH3) emissions in rural areas and oxidized nitrogen (NOx) emissions in urban and industrialized areas.