Proceso y métodos de evaluación integrada participativa de degradación en agroecosistemas semiáridos. Un caso de estudio en un área protegida en el trópico seco nicaragüense.

Ravera F, Tarrasón D, Andrés P, Grasa R (2009) Proceso y métodos de evaluación integrada participativa de degradación en agroecosistemas semiáridos. Un caso de estudio en un área protegida en el trópico seco nicaragüense. Revista Iberoamericana de Economía Ecológica 13: 79-99.

Bioassays prove the suitability of mining debris mixed with sewage sludge for land reclamation purposes

Domene X., Mattana S., Ramírez W., Colón J., Jiménez P., Balanyà T., Alcañiz J.M., Bonmatí M. (2009) Bioassays prove the suitability of mining debris mixed with sewage sludge for land reclamation purposes. Journal of Soils and Sediments. 10: 30-44.
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Doi: 10.1007/s11368-009-0073-1

Resum:

Background, aim, and scope: Mining activities disturb land and reduce its capacity to support a complete functional ecosystem. Reclamation activities in this case are not easy due to the large amount of soil required. This is why mining debris are usually used as surrogate of soil, despite their unsuitable physicochemical properties. However, these properties can be improved with the amendment using an organic source, usually sewage sludge. Nevertheless, the use of sludge might lead to impacts on soil and water ecosystems because of its physicochemical properties and pollutant content. The aim of this study is to assess the suitability of the use of mining debris amended with sewage sludge as practice for the reclamation of land degraded by limestone-quarrying activities. Materials and methods: Two different types of mining debris from the same limestone quarry and six different types of composted or thermally dried sewage sludge were studied. A laboratory assessment was carried out by means of standardized bioassays of sludges, together with a field assessment carried out in lysimeters filled with debris-sludge mixtures. The field assessment was carried out using both the soil-waste mixtures, amended with dosages similar to those used for restoration purposes and their corresponding leachates. The variation of physicochemical properties and the outcomes of different bioassays (soil microorganisms biomass and respiration, enzymatic activities, plant emergence and growth, collembolan survival and reproduction, and the Microtox assay) were used as indicators of fertilizing or ecotoxicological effects. Results: The mining debris used in our study showed a poor capacity for biological recovery, as shown by the lower biological outcomes measured in control lysimeters compared to lysimeters amended with sludge. The addition of sludge improved debris just before the sludge application in terms of its physicochemical and biological properties (microorganism's biomass, respiration and enzymatic activities) which, in some cases, persisted after a year. Conversely, in some sludges, an inhibition in soil collembolans was observed just before the amendment, but any inhibitory effect disappeared after a year. Concerning the leachates obtained from field lysimeters after a week and a year, no inhibitory effects were detectable for aquatic bacteria. Discussion: The effects observed on some of the measured biological endpoints, both in laboratory and field assays, were mainly mediated by physicochemical parameters related to a low stability of organic matter, but in the opposite sense depending on the organism considered. Microbial parameters were enhanced when the organic matter added had a low stability (high content in labile organic matter) but, on the other hand, collembolan performance was negatively affected. The lack of toxicity of leachates indicates a low risk for groundwaters of this reclamation practice. Conclusions: The results of this study support the use of mining debris mixed with sludge for land reclamation of degraded land by quarrying. The addition of sludge allowed a quick plant cover re-establishment and provided a suitable habitat for soil biota because no long-term ecotoxicological risks were observed neither for soils nor groundwaters. The results also indicate that the environmental risk of sludges might be reduced using sludges with a high content in stable organic matter. Recommendations and perspectives: The use of mining debris mixed with sewage sludges for mining reclamation purposes is suitable since long-term ecotoxicological risks were not observed. In addition, the results support the suitability of bioassays for the prediction of the success or risk of specific land reclamation practices in order to avoid unsuccessful attempts. © Springer-Verlag 2009.

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Soil pollution by nonylphenol and nonylphenol ethoxylates and their effects to plants and invertebrates

Domene X., Ramírez W., Solà L., Alcañiz J.M., Andrés P. (2009) Soil pollution by nonylphenol and nonylphenol ethoxylates and their effects to plants and invertebrates. Journal of Soils and Sediments. 9: 555-567.
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Doi: 10.1007/s11368-009-0117-6

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Background, aim, and scope Nonylphenol polyethoxylates (NPEOs) are a widely used class of nonionic surfactants known to be toxic and endocrine-disrupting contaminants. Their use and production have been banned in the European Union and substituted by other surfactants considered as environmentally safer. However, their use continues in many countries without any legal control. Discharges of effluents from wastewater treatment plants and the application of sewage sludge application, land-filling, and accidental spillage to soils are the major sources of NPEOs in the environment. The biodegrada-tion of these surfactants is relatively easy, leading to the accumulation of the simplest chemical forms of non-ylphenol ethoxylates (NP, NP1EO, and NP2EO) and nonylphenol carboxy acids (NP2EC or NP1EC). However, these are also the most toxic end-products and have a higher environmental persistence. Compared to aquatic ecosystems, not much is known about the effects of NPEOs in terrestrial organisms, with few studies mainly centered on the effects on plants and soil microorganisms. The main aim of this study is to provide the range of concentrations of NPEOs with ecotoxicological effects on different plants and soil invertebrate species. In addition, we aim to identify the main soil properties influencing their toxicity. Materials and methods Two natural soils collected and OECD artificial soil were used in toxicity bioassays. Two different NPEO formulations were tested. On the one hand, a technical mixture of NPEOs containing chain isomers and oligomers with an average of eight ethoxy units was used for the experiments and is referred to herein as NP8EO. On the other hand, technical-grade 4-nonylphenol 95% purity was also used and called NP in this study. The chemicals were applied and mixed with soil as an acetone solution. The toxicity of NP8EO and NP was assessed in different taxonomical groups (plants, earthworms, enchytraeids, and collembolans) according to their respective standardized methods. The effect on lethal and sublethal endpoints was assessed and, by means of linear and non-linear regression models, the NPEO concentration causing 10% and 50% inhibition was estimated. The influence of soil properties on the toxicity was assessed using generalized linear models (GLM). Results The chemicals tested showed contrasting toxicities, NP being clearly more toxic than NP8EO. There were also substantial differences in the sensitivity of the species and endpoints, together with clearly different toxicities in different soils. Plants were the least affected group compared to soil invertebrates, since plant endpoints were unaffected or only slightly inhibited. In soil invertebrates, reproduction was the most affected endpoint compared to growth or survival. Toxicity was the lowest in OECD artificial soil in comparison to natural soils, with a lower organic matter content. Discussion The higher toxicity of NP, both in plant and soil invertebrate bioassays, is consistent with previously published studies and its relatively high persistence in soil. The low phytotoxicity of NP8EO and NP, unaffected at concentrations over 1 g NP kg-1, also accords with the known low uptake in plants. The effects on soil inverte-brates appeared at lower concentrations than observed in plants, enchytraeids being less affected by NP8EO than earthworms and collembolans. Drastic inhibition in the invertebrate's endpoints generally appeared over 1 g kg-1 for NP8EO and below 1 g kg-1 for NP. The range of concentrations with effects is in agreement with the few similar studies published to date. Generally, the lowest toxicity values were obtained in OECD soil, with the highest organic matter content, while the highest toxicity was found in the PRA soil, with the lowest content. However, few of the models developed by GLM identified organic carbon as a significant factor in decreasing the bioavailability and toxicity of NPEO. The probable explanation for this is the simultaneous contribution of other soil properties and in particular the limited number of soils used in the bioassays. Conclusions A low ecotoxicological risk of NPEOs might be expected for plants and soil invertebrates, since the usual concentrations in soils (below 2.6 mg kg-1) are clearly less than the lowest concentrations reported to be toxic in our study. Recommendations and perspectives Although the apparent risk of NPEOs for soil ecosystems is limited, such risks should not be neglected since significant concentrations in soil could be reached with elevated application rates or when highly polluted sludges are used. More importantly, NPEO concentrations in soils should be maintained low given the extremely high toxicity for aquatic organisms. Despite the reduced leaching of NPEOs, runoff events might transport NP attached to soil particles and affect adjacent aquatic ecosystems. © Springer-Verlag 2009.

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Climatic drivers of hemispheric asymmetry in global patterns of ant species richness

Dunn R.R., Agosti D., Andersen A.N., Arnan X., Bruhl C.A., Cerdá X., Ellison A.M., Fisher B.L., Fitzpatrick M.C., Gibb H., Gotelli N.J., Gove A.D., Guenard B., Janda M., Kaspari M., Laurent E.J., Lessard J.-P., Longino J.T., Majer J.D., Menke S.B., McGlynn T.P., Parr C.L., Philpott S.M., Pfeiffer M., Retana J., Suarez A.V., Vasconcelos H.L., Weiser M.D., Sanders N.J. (2009) Climatic drivers of hemispheric asymmetry in global patterns of ant species richness. Ecology Letters. 12: 324-333.
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Doi: 10.1111/j.1461-0248.2009.01291.x

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Although many taxa show a latitudinal gradient in richness, the relationship between latitude and species richness is often asymmetrical between the northern and southern hemispheres. Here we examine the latitudinal pattern of species richness across 1003 local ant assemblages. We find latitudinal asymmetry, with southern hemisphere sites being more diverse than northern hemisphere sites. Most of this asymmetry could be explained statistically by differences in contemporary climate. Local ant species richness was positively associated with temperature, but negatively (although weakly) associated with temperature range and precipitation. After contemporary climate was accounted for, a modest difference in diversity between hemispheres persisted, suggesting that factors other than contemporary climate contributed to the hemispherical asymmetry. The most parsimonious explanation for this remaining asymmetry is that greater climate change since the Eocene in the northern than in the southern hemisphere has led to more extinctions in the northern hemisphere with consequent effects on local ant species richness. © 2009 Blackwell Publishing Ltd/CNRS.

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Increasing interannual and altitudinal ozone mixing ratios in the Catalan Pyrenees

Díaz-de-Quijano M., Peñuelas J., Ribas A. (2009) Increasing interannual and altitudinal ozone mixing ratios in the Catalan Pyrenees. Atmospheric Environment. 43: 6049-6057.
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Doi: 10.1016/j.atmosenv.2009.08.035

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Interannual, seasonal, daily and altitudinal patterns of tropospheric ozone mixing ratios, as well as ozone phytotoxicity and the relationship with NOx precursors and meteorological variables were monitored in the Central Catalan Pyrenees (Meranges valley and Forest of Guils) over a period of 5 years (2004-2008). Biweekly measurements using Radiello passive samplers were taken along two altitudinal transects comprised of thirteen stations ranging from 1040 to 2300 m a.s.l. Visual symptoms of ozone damage in Bel-W3 tobacco cultivars were evaluated biweekly for the first three years (2004-2006). High ozone mixing ratios, always above forest and vegetation protection AOT40 thresholds, were monitored every year. In the last 14 years, the AOT40 (Apr-Sept.) has increased significantly by 1047 μg m-3 h per year. Annual means of ozone mixing ratios ranged between 38 and 67 ppbv (38 and 74 ppbv during the warm period) at the highest site (2300 m) and increased at a rate of 5.1 ppbv year-1. The ozone mixing ratios were also on average 35-38% greater during the warm period and had a characteristic daily pattern with minimum values in the early morning, a rise during the morning and a decline overnight, that was less marked the higher the altitude. Whereas ozone mixing ratios increased significantly with altitude from 35 ppbv at 1040 m-56 ppbv at 2300 m (on average for 2004-2007 period), NO2 mixing ratios decreased with altitude from 5.5 ppbv at 1040 m-1 ppbv at 2300 m. The analysis of meteorological variables and NOx values suggests that the ozone mainly originated from urban areas and was transported to high-mountain sites, remaining aloft in absence of NO. Ozone damage rates increased with altitude in response to increasing O3 mixing ratios and a possible increase in O3 uptake due to more favorable microclimatic conditions found at higher altitude, which confirms Bel-W3 as a suitable biomonitor for ozone concentrations during summer time. Compared to the valley-bottom site the annual means of ozone mixing ratios are 37% larger in the higher sites. Thus the AOT40 for the forest and vegetation protection threshold is greatly exceeded at higher sites. This could have substantial effects on plant life at high altitudes in the Pyrenees. © 2009 Elsevier Ltd. All rights reserved.

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Pre-dispersal acorn predation in mixed oak forests: Interspecific differences are driven by the interplay among seed phenology, seed size and predator size

Espelta J.M., Bonal R., Sánchez-Humanes B. (2009) Pre-dispersal acorn predation in mixed oak forests: Interspecific differences are driven by the interplay among seed phenology, seed size and predator size. Journal of Ecology. 97: 1416-1423.
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Doi: 10.1111/j.1365-2745.2009.01564.x

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1. Pre-dispersal seed predation (PSP) often occurs in multi-host-predator systems (e.g. several plant species exposed to a common array of granivorous insects). However, whether the interaction among seed phenology, seed size and predator size accounts for interspecific differences in PSP remains elusive. We studied PSP in a mixed-oak forest with two oaks (the larger-seeded Quercus humilis and the smaller-seeded Q. ilex), both depredated by two acorn weevils (the smaller Curculio glandium and the larger C. elephas). 2.We intensively monitored acorn production and infestation phenology and we identified the weevil species depredating acorns by means of DNA taxonomy. The minimum acorn size required for infestation was lower for C. glandium than for C. elephas, in accordance with their different body sizes. This resulted in an earlier infestation phenology in C. glandium and the ability of this species to infest both smaller and larger acorns. Above a minimum acorn size threshold, no selection for larger acorns by weevils was observed. Initial acorn crop size was similar in the two oaks. Nonetheless, the earlier acorn phenology and the production of larger acorns in Q. humilis favoured the earlier infestation by C. glandium and the predation by both small and large weevils. Smaller acorns of Q. ilex almost excluded infestation by the larger C. elephas. Although larger acorns of Q. humilis could better survive infestation (preserve the embryo), higher PSP in this species finally resulted in a lower mature acorn crop size than in Q. ilex. Synthesis. In a multi-host-predator system, smaller-seeded species may benefit from a reduced PSP because they exclude larger granivorous insects, but also by means of a 'free-rider effect', if larger-seeded heterospecifics earlier reach a critical size to be depredated. These results also highlight the benefits of a small body size in granivorous insects to depredate seeds earlier and to forage on a wider range of seed sizes. Whether the advantage of 'being small' in this antagonistic plant-animal interaction is offset by other processes, or whether it results in a pressure towards seed and insect size reduction, deserves further attention. © 2009 British Ecological Society.

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Acorn crop size and pre-dispersal predation determine inter-specific differences in the recruitment of co-occurring oaks

Espelta J.M., Cortés P., Molowny-Horas R., Retana J. (2009) Acorn crop size and pre-dispersal predation determine inter-specific differences in the recruitment of co-occurring oaks. Oecologia. 161: 559-568.
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Doi: 10.1007/s00442-009-1394-x

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The contribution of pre-dispersal seed predation to inter-specific differences in recruitment remains elusive. In species with no resistance mechanisms, differences in pre-dispersal predation may arise from differences in seed abundance (plant satiation) or in the ability of seeds to survive insect infestation (seed satiation). This study aimed to analyse the impact of pre-dispersal acorn predation by weevils in two co-occurring Mediterranean oaks (Quercus ilex and Quercus humilis) and to compare its relevance with other processes involved in recruitment. We monitored the patterns of acorn production and acorn infestation by weevils and we conducted experimental tests of acorn germination after weevil infestation, post-dispersal predation and seedling establishment in mixed forests. Monitoring and experimental data were integrated in a simulation model to test for the effects of pre-dispersal predation in recruitment. In both oaks pre-dispersal acorn infestation decreased with increasing acorn crop size (plant satiation). This benefited Q. ilex which exhibited stronger masting behaviour than Q. humilis, with almost a single and outstanding reproductive event in 6 years. Acorn infestation was more than twice as high in Q. humilis (47.0%) as in Q. ilex (20.0%) irrespective of the number of seeds produced by each species. Although germination of infested acorns (seed satiation) was higher in Q. humilis (60%) than in Q. ilex (21%), this could barely mitigate the higher infestation rate in the former species, to reduce seed loss. Conversely to pre-dispersal predation, no inter-specific differences were observed either in post-dispersal predation or seedling establishment. Our results indicate that pre-dispersal predation may contribute to differences in seed supply, and ultimately in recruitment, between co-existing oaks. Moreover, they suggest that seed satiation can barely offset differences in seed infestation rates. This serves as a warning against overemphasising seed satiation as a mechanism to overcome seed predation by insects. © Springer-Verlag 2009.

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What happens to ptarmigan when marmots arrive?

Figueroa I., López B.C., López A., Potrony D. (2009) What happens to ptarmigan when marmots arrive?. Ethology Ecology and Evolution. 21: 251-260.
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Doi: 10.1080/08927014.2009.9522480

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Rock ptarmigan is a vulnerable species in the southern Pyrenees, with less than 300 pairs and two unconnected populations. Alpine marmot was introduced in the northern Pyrenees between 1955 and 1988, but they rapidly colonised the southern slopes, with an actual estimated population of around 10,000 individuals. Both species are mainly herbivores, develop their activities on the ground and have their offspring at the same time, so they may compete at various levels. We studied the possible interactions between the two species based on fleld observations, bibliographic data and Geographical Information System (GIS) analysis. We found that alpine marmot has colonised all habitats occupied by rock ptarmigan in the southern Pyrenees, but their plant diet is absolutely differentiated. We also analysed the composition of golden eagle nests and conflrmed that this predator predates the two species. From fleld observations in areas where the two species have coexisted for more than 10 years, we observed no behavioural interaction between the two species. So, although both species share space and time in the alpine communities, both diet differentiation and probably behavioural avoidance permits their coexistence.

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Short-chained oxygenated VOC emissions in Pinus halepensis in response to changes in water availability

Filella I., Peñuelas J., Seco R. (2009) Short-chained oxygenated VOC emissions in Pinus halepensis in response to changes in water availability. Acta Physiologiae Plantarum. 31: 311-318.
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Doi: 10.1007/s11738-008-0235-6

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Short-chained oxygenated VOC (oxVOCs) emissions from Pinus halepensis saplings were monitored in response to changes in water availability. Online measurements were made with a proton transfer reaction-mass spectrometer under controlled conditions, together with CO2 and H2O exchange measurements. Masses corresponding to methanol and acetone were the most emitted oxVOCs. All the oxVOC exchanges, except that of acetone (M59), were significantly related to stomatal conductance and transpiration. Acetaldehyde (M45) emission showed, moreover, a strong dependence on the concentration of acetaldehyde in the ambient: stomatal opening (stomatal conductance above 75 mmol m-2 s-1) only allowed increased emissions when external concentration were below 6 ppb. Acetone (M59) presented an important peak of emission following light and stomatal opening in the morning when plants were water stressed. Thus, the alterations in oxVOC emissions in P. halepensis caused by the water deficit seem to be mainly driven by water stress effect on stomatal closure and oxVOC air concentrations. © 2008 Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Kraków.

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PRI assessment of long-term changes in carotenoids/chlorophyll ratio and short-term changes in de-epoxidation state of the xanthophyll cycle

Filella I., Porcar-Castell A., Munné-Bosch S., Bäck J., Garbulsky M.F., Peñuelas J. (2009) PRI assessment of long-term changes in carotenoids/chlorophyll ratio and short-term changes in de-epoxidation state of the xanthophyll cycle. International Journal of Remote Sensing. 30: 4443-4455.
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Doi: 10.1080/01431160802575661

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The Photochemical Reflectance Index (PRI), an index based on leaf reflectance at 531 nm, has been found suitable for tracking variations in photosynthetic activity from leaf to ecosystem levels. This suitability has been attributed to PRI correlation with xanthophyll interconversion and photosynthetic radiation-use efficiency. However, other pigments and factors may be involved in such relationships. We studied the relationship between PRI and xanthophylls and other carotenoids in saplings of two widely distributed evergreen species (Scots pine and Holm oak) submitted to experimentally changing light conditions in a field experiment. PRI was strongly correlated with the de-epoxidation state of xanthophylls (DEPS, an expression of the relative concentration of the three xanthophyll cycle pigments), but also with carotenoids/chlorophyll ratio and β-carotene/chlorophyll ratio in both species. However, following momentary decreases in light due to clouds, PRI changed following the DEPS changes, while the carotenoids/chlorophyll ratio remained constant. The results show that PRI was able to reveal short-term changes in de-epoxidation state, i.e. the signal of xanthophyll interconversion, but it also tracked long-term changes in carotenoids/chlorophyll. Carotenoids other than xanthophylls, e.g. β-carotene, are also related to photoprotective processes, thus also making PRI effective as a measure of changes in photosynthetic light-use efficiency in response to stress on a long-term level. © 2009 Taylor & Francis.

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