Browsing by Subject "Functional traits"

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    Functional redundancy as a tool for bioassessment: A test using riparian vegetation
    (Elsevier, 2016-06-05) Bruno, Daniel; Gutiérrez Cánovas, Cayetano; Velasco, Josefa; Sánchez Fernández, David; Ecología e Hidrología
    There is an urgent need to track how natural systems are responding to global change in order to better guide management efforts. Traditionally, taxonomically based metrics have been used as indicators of ecosystem integrity and conservation status. However, functional approaches offer promising advantages that can improve bioassessment performance. In this study,we aimto test the applicability of functional redundancy (FR), a functional feature related to the stability, resistance and resilience of ecosystems, as a tool for bioassessment, looking at woody riparian communities in particular. We used linear mixed-effect models to investigate the response of FR and other traditional biomonitoring indices to natural (drought duration) and anthropogenic stress gradients (flow regulation and agriculture) in a Mediterranean basin. Such indices include species richness, a taxonomic index, and the Riparian Quality Index, which is an index of ecological status. Then, we explored the ability of FR and the other indices to discriminate between different intensities of human alteration. FR showed higher explanatory capacity in response to multiple stressors, although we found significant negative relationships between all the biological indices (taxonomic, functional and ecological quality) and stress gradients. In addition, FRwas the most accurate index to discriminate among different categories of human alteration in both perennial and intermittent river reaches, which allowed us to set threshold values to identify undisturbed (reference condition), moderately disturbed and highly disturbed reaches in the two types of river. Using these thresholds and the best-fitting model, we generated a map of human impact on the functional redundancy of riparian communities for all the stretches of the river network. Our results demonstrate that FR presents clear advantages over traditional methods, which suggests that it should be part of the biomonitoring toolbox used for environmental management so as to obtain better predictions of ecosystem response to environmental changes.
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    Impacts of environmental filters on functional redundancy in riparian vegetation
    (Wiley / British Ecological Society, 2016-06) Bruno, Daniel; Gutiérrrez Cánovas, Cayetano; Sánchez Fernández, David; Velasco, Josefa; Nilsson, Christer; Ecología e Hidrología
    Understanding and predicting ecosystem responses to multiple environmental pressures is a long-standing interest in ecology and environmental management. However, few studies have examined how the functional features of freshwater biological communities vary along multiple gradients of environmental stress. Furthermore, modelling these functional features for a whole river network constitutes a strong potential basis to improve ecosystem management. We explored how functional redundancy of biological communities (FR, a functional feature related to the stability, resistance and resilience of ecosystems) responds to single and multiple environmental filters. We compared these responses with those of functional richness, evenness and divergence. We used riparian vegetation of a Mediterranean basin, and three of the main environmental filters affecting freshwater communities in such regions, that is drought, flow regulation and agricultural intensity, thus considering the potential effect of natural environmental variability. We also assessed the predictability of FR and estimated it for the entire river network. We found that all functional measures decreased with increasing environmental filter intensity. However, FR was more sensitive to single and multiple environmental filters compared to other functional measures. The best-fitting model explained 59% of the FR variability and included agriculture, drought and flow regulation and the pairwise interactions of agriculture with drought and flow regulation. The parameters of the FR models differed from null model expectations reflecting a non-random decline along stress gradients. Synthesis and applications. We found non-random detrimental effects along environmental filters' gradients for riparian functional redundancy (the most sensitive functional index), meaning that increased stress could jeopardize stability, resistance and resilience of these systems. In general, agriculture caused the greatest impact on functional redundancy and functional diversity measures, being the most important stressor for riparian functionality in the study area. Temporary streams flowing through an agricultural, regulated basin had reduced values of functional redundancy, whereas the free-flowing medium-sized, perennial water courses flowing through unaltered sub-basins displayed higher values of functional redundancy and potentially greater stability against human impacts. All these findings along with the predicted basin-wide variation of functional redundancy can assist environmental managers in improving monitoring and ecosystem management.
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    Shifting baselines in a Mediterranean small-scale fishery
    (Elsevier, 2019-09-24) Leitao, Pedro; Henriques, Sofia; Pérez Ibarra, Irene; García Charton, José Antonio; Trujillo, María; Vasconcelos, Rita P.; Ecología e Hidrología
    The overexploitation of marine resources has led to a decrease in species abundance over time in many marine ecosystems worldwide. But as new fishers arise throughout the years, the perception of local abundance changes which might result in a “shifting baselines syndrome”. We investigated how the perception of fishers about species abundance changed through time (from 1970 to 2016) and space (five ports), through questionnaires in the small-scale/artisanal fisheries of Murcia, Spain. Two major results emerged, firstly species catches significantly decreased between the decades 1970–1990 and 2000–2016, possibly due to overfishing and habitat degradation. Catches of species with some particular functional traits decreased (96%) possibly due to lower plasticity or to a “fishing down the food web” effect. Secondly, some functional trait categories (very large size, deep water depth, large yearly displacements and very vagile) were the highest in the northern ports of San Pedro del Pinatar and Cartagena while Cabo de Palos had the highest values in species with solitary and territorial behaviour and vagile or sedentary mobility. Fishers’ perception of catch trends of commercial species seemed aligned with other sources of information for this area and might be key information in the absence of more quantitative information.