Eduardo González

Forecasting functional implications of global changes in riparian plant communities

Riparian ecosystems support mosaics of terrestrial and aquatic plant species that enhance regional biodiversity and provide important ecosystem services to humans. Species composition and the distribution of functional traits – traits that define species in terms of their ecological roles – within riparian plant communities are rapidly changing in response to various global change drivers. Here, we present a conceptual framework illustrating how changes in dependent wildlife communities and ecosystem processes can be predicted by examining shifts in riparian plant functional trait diversity and redundancy (overlap). Three widespread examples of altered riparian plant composition are: shifts in the dominance of deciduous and coniferous species; increases in drought-tolerant species; and the increasing global distribution of plantation and crop species. Changes in the diversity and distribution of critical plant functional traits influence terrestrial and aquatic food webs, organic matter production and pro...

Abrupt Drops in Water Table Level Influence the Development of Populus nigra and Salix alba Seedlings of Different Ages

Early seedling establishment is a demographic bottleneck for the sexual regeneration of many riparian tree species such as Populus nigra and Salix alba, two dominant species of European floodplains. Immediately after spring germination, seedling roots must track receding water tables to avoid desiccation. This may be especially difficult if the groundwater recession is too abrupt. In this study, seedling survival and growth under different abrupt drops in water table levels were examined using an experimental facility that allowed continuous and non-destructive measurements of above- and below-ground seedling development. A Cox proportional hazards regression model showed that the risk of mortality for a seedling was significantly lower in P. nigra than in S. alba, was lower for older than for younger seedlings, and increased with greater drops in water table level. In fact, almost no seedlings survived abrupt water level drops ≥40xa0cm. However, no substantial differences in any of the growth parameters were observed between species, age, and water table treatments, as shown by R-ANOVA and paired tests. This suggests that abrupt drops in water table level did not stimulate plant growth but only favoured the survival of the most resistant individuals. These findings should be considered when designing improved water flow prescriptions along managed river courses in Europe.

Wetland Restoration: Integrating Scientific-Technical, Economic, and Social Perspectives

ECOLOGICAL RESTORATION 23:3 ■ SEPTEMBER 2005 Ecological Restoration, Vol. 23, No. 3, 2005 ISSN 1522-4740 E-ISSN 1543-4079 ©2005 by the Board of Regents of the University of Wisconsin System. Wetlands are being restored around the world using a wide spectrum of different approaches from the application of well-grounded scientific knowledge to obtain a precise objective to trial-and-error practices just to have water for some time on a piece of land. Whatever the methodology, wetland restoration projects can provide good theoretical and practical knowledge because, compared to other ecosystems, wetland ecosystems react relatively soon to manipulations (Mitsch and Gosselink 2000, Zentner and others 2003). Given this range of approaches, it must also be noted that the success of an ecological restoration project depends on many factors that should be taken into account when planning and developing a project. These can be grouped into three types: 1) technical failures or lack of scientific information, 2) economic constraints, and 3) social disagreements. The integration of these three perspectives— scientific-technical, economic and social —is important to obtain all the values of an ecological restoration project (Comín 2002, Winterhalder and others 2004). In this article, we present a number of wetland restoration experiences developed under different conditions in northeastern Spain in order to look for common recommendations for planning future, highvalue projects.

Assessing metal pollution in ponds constructed for controlling runoff from reclaimed coal mines

Constructing ponds to protect downstream ecosystems is a common practice in opencast coal mine reclamation. As these ponds remain integrated in the landscape, it is important to evaluate the extent of the effect of mine pollution on these ecosystems. However, this point has not been sufficiently addressed in the literature. The main objective of this work was to explore the metal pollution in man-made ponds constructed for runoff control in reclaimed opencast coal mines over time. To do so, we evaluated the concentration of ten heavy metals in the water, sediment, and Typha sp. in 16 runoff ponds ranging from 1 to 19xa0years old that were constructed in reclaimed opencast coal mines of northeastern Spain. To evaluate degree of mining pollution, we compared these data to those from a pit lake created in a local unreclaimed mine and to local streams as an unpolluted reference, as well as comparing toxicity levels in aquatic organisms. The runoff ponds showed toxic concentrations of Al, Cu, and Ni in the water and As and Ni in the sediment, which were maintained over time. Metal concentrations in runoff ponds were higher than in local streams, and macrophytes showed high metal concentrations. Nevertheless, metal concentrations in water and sediment in runoff ponds were lower than those in the pit lake. This study highlights the importance of mining reclamation to preserve the health of aquatic ecosystems and suggests the existence of chronic metal toxicity in the ponds, potentially jeopardizing pond ecological functions and services.