Rui Figueira

Distribution of trace metals in moss biomonitors and assessment of contamination sources in Portugal.

A biomonitoring survey using the moss species [Hypnum cupressiforme Hedw. and Scelopodium touretii (Brid.) L. Kock] was performed in the whole territory of Portugal, in order to evaluate the atmospheric deposition of the following elements: Cd. Cr, Cu, Fe, Mn, Ni, Pb and Zn. The concentrations of the same elements were also obtained in two types of soil samples, collected under the moss and in nearby plots without any plant coverage, and relationships between moss and soil concentrations was investigated using the multivariate statistical method of Co-inertia Analysis. Also, relationships between concentrations in moss and several anthropogenic, geologic, pedologic and environmental parameters were screened using the same method of Co-inertia Analysis. Higher concentrations of Cu, Pb and Zn were found in areas of higher population density, with higher gasoline consumption, while higher values of Fe and Cr occur in the driest region, with lower plant coverage, indicating strong contamination by resuspended soil particles. Results also show good agreement between moss and soil contents, even for elements with high contribution of anthropogenic sources. The spatial pattern in Portugal of element contents in mosses were also detected and discussed in relation to local contamination sources.

Country-specific correlations across Europe between modelled atmospheric cadmium and lead deposition and concentrations in mosses

Previous analyses at the European scale have shown that cadmium and lead concentrations in mosses are primarily determined by the total deposition of these metals. Further analyses in the current study show that Spearman rank correlations between the concentration in mosses and the deposition modelled by the European Monitoring and Evaluation Programme (EMEP) are country and metal-specific. Significant positive correlations were found for about two thirds or more of the participating countries in 1990, 1995, 2000 and 2005 (except for Cd in 1990). Correlations were often not significant and sometimes negative in countries where mosses were only sampled in a relatively small number of EMEP grids. Correlations frequently improved when only data for EMEP grids with at least three moss sampling sites per grid were included. It was concluded that spatial patterns and temporal trends agree reasonably well between lead and cadmium concentrations in mosses and modelled atmospheric deposition.

Investigating tree bark as an air-pollution biomonitor by means of neutron activation analysis

The olive tree (Olea europaea) is an icon of southern Europe and awidespread evergreen in mainland Portugal. First results of a continuing studyon the ability of olive-tree bark to act as an air-pollution biomonitor arepresented and discussed here. Other than lower signals and an anticipatedsystemic control over some elements, there seems to be no a priori reasonfor ruling out the possibility of using bark in atmospheric trace-elementsurveys. In fact, nonparametric statistics show that, despite their relativemagnitude, the variation patterns of bark and lichen concentrations significantlyfollow one another all across the study area.

Observations of heavy metal accumulation in the cell walls of Fontinalis antipyretica, in a Portuguese stream affected by mine effluent

Abstract Transplants of Fontinalis antipyretica were used for assessment of metal contamination, caused by mine effluent, in a natural stream. A strong increase of total Cu, Mn and Ni was observed in plants 27 days after transplantation. Scanning electron microscopy of transplanted material showed the presence of concentric insoluble deposits, irregularly located on the surface of plant leaves. Such deposits were not identified on the surface of dead cells and, presumably, are formed by biological activity of the bryophyte. The analysis of deposits by X-ray microanalysis showed strong enrichment of Mn. This could be the result of high availability of soluble Mn in an oxidative environment, caused by oxygen released by photosynthesis.

Application of indicator kriging to the complementary use of bioindicators at three trophic levels.

The use of biological indicators is widespread in environmental monitoring, although it has long been recognised that each bioindicator is generally associated with a range of potential limitations and shortcomings. To circumvent this problem, this study adopted the complementary use of bioindicators representing different trophic levels and providing different type of information, in an innovative approach to integrate knowledge and to estimate the overall health state of ecosystems. The approach is illustrated using mercury contamination in primary producers (mosses), primary consumers (domestic pigeons and red-legged partridges) and top predators (Bonellis eagles) in southern Portugal. Indicator kriging geostatistics was used to identify the areas where mercury concentration was higher than the median for each species, and to produce an index that combines mercury contamination across trophic levels. Spatial patterns of mercury contamination were consistent across species. The combined index provided a new level of information useful in incorporating measures of overall environmental contamination into pollution studies.

Exploring the floristic diversity of tropical Africa

BackgroundUnderstanding the patterns of biodiversity distribution and what influences them is a fundamental pre-requisite for effective conservation and sustainable utilisation of biodiversity. Such knowledge is increasingly urgent as biodiversity responds to the ongoing effects of global climate change. Nowhere is this more acute than in species-rich tropical Africa, where so little is known about plant diversity and its distribution. In this paper, we use RAINBIO – one of the largest mega-databases of tropical African vascular plant species distributions ever compiled – to address questions about plant and growth form diversity across tropical Africa.ResultsThe filtered RAINBIO dataset contains 609,776 georeferenced records representing 22,577 species. Growth form data are recorded for 97% of all species. Records are well distributed, but heterogeneous across the continent. Overall, tropical Africa remains poorly sampled. When using sampling units (SU) of 0.5°, just 21 reach appropriate collection density and sampling completeness, and the average number of records per species per SU is only 1.84. Species richness (observed and estimated) and endemism figures per country are provided. Benin, Cameroon, Gabon, Ivory Coast and Liberia appear as the botanically best-explored countries, but none are optimally explored. Forests in the region contain 15,387 vascular plant species, of which 3013 are trees, representing 5–7% of the estimated world’s tropical tree flora. The central African forests have the highest endemism rate across Africa, with approximately 30% of species being endemic.ConclusionsThe botanical exploration of tropical Africa is far from complete, underlining the need for intensified inventories and digitization. We propose priority target areas for future sampling efforts, mainly focused on Tanzania, Atlantic Central Africa and West Africa. The observed number of tree species for African forests is smaller than those estimated from global tree data, suggesting that a significant number of species are yet to be discovered. Our data provide a solid basis for a more sustainable management and improved conservation of tropical Africa’s unique flora, and is important for achieving Objective 1 of the Global Strategy for Plant Conservation 2011–2020.

RAINBIO: a mega-database of tropical African vascular plants distributions

Abstract The tropical vegetation of Africa is characterized by high levels of species diversity but is undergoing important shifts in response to ongoing climate change and increasing anthropogenic pressures. Although our knowledge of plant species distribution patterns in the African tropics has been improving over the years, it remains limited. Here we present RAINBIO, a unique comprehensive mega-database of georeferenced records for vascular plants in continental tropical Africa. The geographic focus of the database is the region south of the Sahel and north of Southern Africa, and the majority of data originate from tropical forest regions. RAINBIO is a compilation of 13 datasets either publicly available or personal ones. Numerous in depth data quality checks, automatic and manual via several African flora experts, were undertaken for georeferencing, standardization of taxonomic names and identification and merging of duplicated records. The resulting RAINBIO data allows exploration and extraction of distribution data for 25,356 native tropical African vascular plant species, which represents ca. 89% of all known plant species in the area of interest. Habit information is also provided for 91% of these species.

Documenting biogeographical patterns of African timber species using herbarium records: a conservation perspective based on native trees from Angola.

In many tropical regions the development of informed conservation strategies is hindered by a dearth of biodiversity information. Biological collections can help to overcome this problem, by providing baseline information to guide research and conservation efforts. This study focuses on the timber trees of Angola, combining herbarium (2670 records) and bibliographic data to identify the main timber species, document biogeographic patterns and identify conservation priorities. The study recognized 18 key species, most of which are threatened or near-threatened globally, or lack formal conservation assessments. Biogeographical analysis reveals three groups of species associated with the enclave of Cabinda and northwest Angola, which occur primarily in Guineo-Congolian rainforests, and evergreen forests and woodlands. The fourth group is widespread across the country, and is mostly associated with dry forests. There is little correspondence between the spatial pattern of species groups and the ecoregions adopted by WWF, suggesting that these may not provide an adequate basis for conservation planning for Angolan timber trees. Eight of the species evaluated should be given high conservation priority since they are of global conservation concern, they have very restricted distributions in Angola, their historical collection localities are largely outside protected areas and they may be under increasing logging pressure. High conservation priority was also attributed to another three species that have a large proportion of their global range concentrated in Angola and that occur in dry forests where deforestation rates are high. Our results suggest that timber tree species in Angola may be under increasing risk, thus calling for efforts to promote their conservation and sustainable exploitation. The study also highlights the importance of studying historic herbarium collections in poorly explored regions of the tropics, though new field surveys remain a priority to update historical information.

Development and calibration of epiphytic lichens as saltfall biomonitors—dry-deposition modelling

Lichen transplants (Ramalina calicaris and Usnea spp.) were investigated as biomonitors of the atmospheric deposition of marine salt, and a calibration model was set up to predict the dry deposition of saline elements from the concentration of salt tracers in lichens. The study was performed in the Portuguese Atlantic coast, where a monthly transplantation program was run in two stations that show clear differences in terms of precipitation regimes. At both stations, dry deposition and precipitation records were kept for the whole duration of the program. General trends in results have indicated that rainwater may wash saline elements out of lichens, though such an effect does not appear to be linear. A multiple-regression approach was taken to look for a calibration between dry-deposition fluxes and lichen concentrations through a stepwise technique. The calibration model for data obtained in both stations features two break points that define precipitation ranges for low, moderate and heavy rain conditions. The results show that lichens can really be used to indicate the dry deposition of sea salt.

Microhabitat effects on bryophyte species richness and community distribution on exposed rock outcrops in Portugal

Background: Rock outcrops have been shown to provide specific conditions for bryophyte communities, but no studies have focused on the importance of microhabitats on such communities. Aim: To analyse the distribution pattern of bryophyte species from granite and schist outcrops in three microhabitats (rock surfaces, fissures and cavities) in Portugal. Methods: Sample plots were established in fissures, cavities and on rock surfaces of rock outcrops in north and central Portugal. Micro-scale variables, such as exposure and slope were assessed for each microhabitat. Results: The microhabitats most different in species composition were surfaces versus cavities and surfaces versus fissures, both on granite and schist. Short-lived shuttle species tended to be associated with surfaces, and perennial species were more frequent in cavities and fissures. Both on granite and schist, the number of species found in each microhabitat was highest in cavities, followed by fissures and rock surfaces. The most relevant predictors of bryophyte richness were microhabitat type, exposure and rock type. Conclusions: This investigation confirmed that rock microhabitats play an important role in bryophyte diversity by promoting habitat heterogeneity. In addition, our results clearly suggest local explanations for variation in bryophyte species richness and communities.