Muhammad-Nor S.M., Huxham M., Salmon Y., Duddy S.J., Mazars-Simon A., Mencuccini M., Meir P., Jackson G. (2019) Exceptionally high mangrove root production rates in the Kelantan Delta, Malaysia; An experimental and comparative study. Forest Ecology and Management. 444: 214-224.EnllaçDoi: 10.1016/j.foreco.2019.04.026
Mangroves often allocate a relatively large proportion of their total biomass production to their roots, and the belowground biomass of these forests contributes towards globally significant carbon sinks. However, little information is available on root production in mangroves due to the difficulties in carrying out measurements of belowground processes, particularly if there is regular flooding. In this study, we examined fine and coarse root production in the east coast of the Malaysian Peninsula. Ingrowth cores were used over the course of 17 months. In September 2014, twenty cores were randomly placed in each of five plots. Three cores were collected from each plot (fifteen cores in total), once every three months. Each core was divided into five 10 cm layers and root dry mass was recorded. Standing root biomass was also measured at the time of final collection using an additional 15 cores. There was a seasonal pattern in root production, which peaked in March and December 2015, after and during the monsoon season. Root biomass in the cores peaked at 33.23 ± 6.3 t ha −1 and 21.46 ± 7.3 t ha −1 in March and December respectively. Standing root biomass in February 2016 in the forest was 20.81 ± 2.8 t ha −1 . After 17 months, the final root biomass in the cores was 14% less than the standing root biomass. These data suggest surprisingly rapid growth rates and turnover for mangrove roots. Total root biomass significantly increased with root depth and 78% of the roots, in all soil layers, consisted of fine roots (<3 mm diameter). Soil carbon, nitrogen and phosphorous concentrations were investigated in relation to belowground production, as were soil temperature, salinity and dissolved oxygen. A data review of global studies reporting similar work was carried out. The results are discussed with consideration to the significance of monsoon rainfall for mangrove ecology. © 2019 Elsevier B.V.
Padró J.-C., Carabassa V., Balagué J., Brotons L., Alcañiz J.M., Pons X. (2019) Monitoring opencast mine restorations using Unmanned Aerial System (UAS) imagery. Science of the Total Environment. 657: 1602-1614.EnllaçDoi: 10.1016/j.scitotenv.2018.12.156
Open-pit mine is still an unavoidable activity but can become unsustainable without the restoration of degraded sites. Monitoring the restoration after extractive activities is a legal requirement for mine companies and public administrations in many countries, involving financial provisions for environmental liabilities. The objective of this contribution is to present a rigorous, low-cost and easy-to-use application of Unmanned Aerial Systems (UAS) for supporting opencast mining and restoration monitoring, complementing the inspections with very high (
Penuelas J., Baldocchi D. (2019) Life and the five biological laws. Lessons for global change models and sustainability. Ecological Complexity. 38: 11-14.EnllaçDoi: 10.1016/j.ecocom.2019.02.001
Life on Earth is the result of a continuous accumulation of information by combination and innovation using endo- (inside the organism) and exosomatic (outside the organism) energy. Sustenance occurs through cycles of life and death. We here define five life laws for these vital processes. These processes cannot exceed natural limits of size and rates because they are constrained by space, matter and energy; biology builds on what is possible within these physicochemical limits. Learning from the way nature deals with the accumulation of information, the limits of size and the rates at which life can acquire and expend energy and resources for maintenance, growth and competition will help us to model and manage our environmental future and sustainability. © 2019 Elsevier B.V.
Peterson A.T., Anderson R.P., Beger M., Bolliger J., Brotons L., Burridge C.P., Cobos M.E., Cuervo-Robayo A.P., Di Minin E., Diez J., Elith J., Embling C.B., Escobar L.E., Essl F., Feeley K.J., Hawkes L., Jiménez-García D., Jimenez L., Green D.M., Knop E., Kühn I., Lahoz-Monfort J.J., Lira-Noriega A., Lobo J.M., Loyola R., Mac Nally R., Machado-Stredel F., Martínez-Meyer E., McCarthy M., Merow C., Nori J., Nuñez-Penichet C., Osorio-Olvera L., Pyšek P., Rejmánek M., Ricciardi A., Robertson M., Rojas Soto O., Romero-Alvarez D., Roura-Pascual N., Santini L., Schoeman D.S., Schröder B., Soberon J., Strubbe D., Thuiller W., Traveset A., Treml E.A., Václavík T., Varela S., Watson J.E.M., Wiersma Y., Wintle B., Yanez-Arenas C., Zurell D. (2019) Open access solutions for biodiversity journals: Do not replace one problem with another. Diversity and Distributions. 25: 5-8.EnllaçDoi: 10.1111/ddi.12885
[No abstract available]
Peñuelas J., Fernández-Martínez M., Ciais P., Jou D., Piao S., Obersteiner M., Vicca S., Janssens I.A., Sardans J. (2019) The bioelements, the elementome, and the biogeochemical niche. Ecology. 100: 0-0.EnllaçDoi: 10.1002/ecy.2652
Every living creature on Earth is made of atoms of the various bioelements that are harnessed in the construction of molecules, tissues, organisms, and communities, as we know them. Organisms need these bioelements in specific quantities and proportions to survive and grow. Distinct species have different functions and life strategies, and have therefore developed distinct structures and adopted a certain combination of metabolic and physiological processes. Each species is thus also expected to have different requirements for each bioelement. We therefore propose that a “biogeochemical niche” can be associated with the classical ecological niche of each species. We show from field data examples that a biogeochemical niche is characterized by a particular elementome defined as the content of all (or at least most) bioelements. The differences in elementome among species are a function of taxonomy and phylogenetic distance, sympatry (the bioelemental compositions should differ more among coexisting than among non-coexisting species to avoid competitive pressure), and homeostasis with a continuum between high homeostasis/low plasticity and low homeostasis/high plasticity. This proposed biogeochemical niche hypothesis has the advantage relative to other associated theoretical niche hypotheses that it can be easily characterized by actual quantification of a measurable trait: the elementome of a given organism or a community, being potentially applicable across taxa and habitats. The changes in bioelemental availability can determine genotypic selection and therefore have a feedback on ecosystem function and organization, and, at the end, become another driving factor of the evolution of life and the environment. © 2019 by the Ecological Society of America
Poblador S., Thomas Z., Rousseau-Gueutin P., Sabaté S., Sabater F. (2019) Riparian forest transpiration under the current and projected Mediterranean climate: Effects on soil water and nitrate uptake. Ecohydrology. 12: 0-0.EnllaçDoi: 10.1002/eco.2043
Vegetation plays a key role in riparian area functioning by controlling water and nitrate (N─NO3 −) transfers to streams. We investigated how spatial heterogeneity modifies the influence of vegetation transpiration on soil water and N─NO3 − balances in the vadose soil of a Mediterranean riparian forest. On the basis of field data, we simulated water flow and N─NO3 − transport in three riparian zones (i.e., near-stream, intermediate, and hillslope) using HYDRUS-1D model. We investigated spatiotemporal patterns across the riparian area over a 3-year period and future years using an IPCC/CMIP5 climate projection for the Mediterranean region. Potential evapotranspiration was partitioned between evaporation and transpiration to estimate transpiration rates at the area. Denitrification in the forest was negligible, thus N─NO3 − removal was only considered through plant uptake. For the three riparian zones, the model successfully predicted field soil moisture (θ). The near-stream zone exchanged larger volumes of water and supported higher θ and transpiration rates (666 ± 75 mm) than the other two riparian zones. Total water fluxes, θ, and transpiration rates decreased near the intermediate (536 ± 46 mm transpired) and hillslope zones (406 ± 26 mm transpired), suggesting that water availability was restricted due to deeper groundwater. Transpiration strongly decreased θ and soil N─NO3 − in the hillslope and intermediate zones. Our climate projections highlight the importance of groundwater availability and indicate that soil N─NO3 − would be expected to increase due to changes in plant-root uptake. Lower water availability in the hillslope zone may reduce the effectiveness of N─NO3 − removal in the riparian area, increasing the risk of excess N─NO3 − leaching into the stream. © 2018 John Wiley & Sons, Ltd.
Poyatos R., Aguadé D., Martínez-Vilalta J. (2019) Correction to: Below-ground hydraulic constraints during drought-induced decline in Scots pine (Annals of Forest Science, (2018), 75, 4, (100), 10.1007/s13595-018-0778-7). Annals of Forest Science. 76: 0-0.EnllaçDoi: 10.1007/s13595-019-0825-z
The article was published without the submitted data availability statement linking readers to a public repository. Due to publication modifications, the information appears missing in the original article. The following corrects previous version of the statement: Data availability The datasets generated and/or analysed during the current study are available in Zenodo Repository (Poyatos et al. 2018). The datasets were not peer reviewed. The original article has been corrected. © 2019, INRA and Springer-Verlag France SAS, part of Springer Nature.
Preece C., Verbruggen E., Liu L., Weedon J.T., Peñuelas J. (2019) Effects of past and current drought on the composition and diversity of soil microbial communities. Soil Biology and Biochemistry. 131: 28-39.EnllaçDoi: 10.1016/j.soilbio.2018.12.022
Drought is well known to have strong effects on the composition and activity of soil microbial communities, and may be determined by drought history and drought duration, but the characterisation and prediction of these effects remains challenging. This is because soil microbial communities that have previously been exposed to drought may change less in response to subsequent drought events, due to the selection of drought-resistant taxa. We set up a 10-level drought experiment to test the effect of water stress on the composition and diversity of soil bacterial and fungal communities. We also investigated the effect of a previous long-term drought on communities in soils with different historical precipitation regimes. Saplings of the holm oak, Quercus ilex L., were included to assess the impact of plant presence on the effects of the drought treatment. The composition and diversity of the soil microbial communities were analysed using DNA amplicon sequencing of bacterial and fungal markers and the measurement of phospholipid fatty acids. The experimental drought affected the bacterial community much more than the fungal community, decreasing alpha diversity and proportion of total biomass, whereas fungal diversity tended to increase. The experimental drought altered the relative abundances of specific taxa of both bacteria and fungi, and in many cases these effects were modified by the presence of the plant and soil origin. Soils with a history of drought had higher overall bacterial alpha diversity at the end of the experimental drought, presumably because of adaptation of the bacterial community to drought conditions. However, some bacterial taxa (e.g. Chloroflexi) and fungal functional groups (plant pathogens and saprotrophic yeasts) decreased in abundance more in the pre-droughted soils. Our results suggest that soil communities will not necessarily be able to maintain the same functions during more extreme or more frequent future droughts, when functions are influenced by community composition. Drought is likely to continue to affect community composition, even in soils that are acclimated to it, tending to increase the proportion of fungi and reduce the proportion and diversity of bacteria. © 2018 Elsevier Ltd
Rao K., Anderegg W.R.L., Sala A., Martínez-Vilalta J., Konings A.G. (2019) Satellite-based vegetation optical depth as an indicator of drought-driven tree mortality. Remote Sensing of Environment. 227: 125-136.EnllaçDoi: 10.1016/j.rse.2019.03.026
Drought-induced tree mortality events are expected to increase in frequency under climate change. However, monitoring and modeling of tree mortality is limited by the high spatial variability in vegetation response to climatic drought stress and lack of physiologically meaningful stress variables that can be monitored at large scales. In this study, we test the hypothesis that relative water content (RWC) estimated by passive microwave remote sensing through vegetation optical depth can be used as an empirical indicator of tree mortality that both integrates variations in plant drought stress and is accessible across large areas. The hypothesis was tested in a recent severe drought in California, USA. The RWC showed a stronger threshold relationship with mortality than climatic water deficit (CWD) – a commonly used mortality indicator – although both relationships were noisy due to the coarse spatial resolution of the data (0.25° or approximately 25 km). In addition, the threshold for RWC was more uniform than that for CWD when compared between Northern and Southern regions of California. A random forests regression (machine learning) with 32 variables describing topography, climate, and vegetation characteristics predicted forest mortality extent i.e. fractional area of mortality (FAM) with satisfactory accuracy-coefficient of determination R test 2 = 0.66, root mean square error = 0.023. Importantly, RWC was more than twice as important as any other variable in the model in estimating mortality, confirming its strong link to mortality rates. Moreover, RWC showed a moderate ability to aid in forecasting mortality, with a relative importance of RWC measured one year in advance of mortality similar to that of other relevant explanatory variables measured in the mortality year. The results of this study present a promising new approach to estimate drought stress of forests linked to mortality risk. © 2019 Elsevier Inc.
Ribeiro I., Proença V., Serra P., Palma J., Domingo-Marimon C., Pons X., Domingos T. (2019) Remotely sensed indicators and open-access biodiversity data to assess bird diversity patterns in Mediterranean rural landscapes. Scientific Reports. 9: 0-0.EnllaçDoi: 10.1038/s41598-019-43330-3
Biodiversity monitoring at simultaneously fine spatial resolutions and large spatial extents is needed but limited by operational trade-offs and costs. Open-access data may be cost-effective to address those limitations. We test the use of open-access satellite imagery (NDVI texture variables) and biodiversity data, assembled from GBIF, to investigate the relative importance of variables of habitat extent and structure as indicators of bird community richness and dissimilarity in the Alentejo region (Portugal). Results show that, at the landscape scale, forest bird richness is better indicated by the availability of tree cover in the overall landscape than by the extent or structure of the forest habitats. Open-land birds also respond to landscape structure, namely to the spectral homogeneity and size of open-land patches and to the presence of perennial vegetation amid herbaceous habitats. Moreover, structure variables were more important than climate variables or geographic distance to explain community dissimilarity patterns at the regional scale. Overall, summer imagery, when perennial vegetation is more discernible, is particularly suited to inform indicators of forest and open-land bird community richness and dissimilarity, while spring imagery appears to be also useful to inform indicators of open-land bird richness. © 2019, The Author(s).
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