Weather and trade-offs between growth and reproduction regulate fruit production in European forests

Vergotti M.J., Fernández-Martínez M., Kefauver S.C., Janssens I.A., Peñuelas J. (2019) Weather and trade-offs between growth and reproduction regulate fruit production in European forests. Agricultural and Forest Meteorology. 279: 0-0.
Enlace
Doi: 10.1016/j.agrformet.2019.107711

Resumen:

Some tree species have a highly variable year-to-year pattern of reproduction which has repercussions for the entire ecosystem. Links between meteorological variability, fruit production and crown cover, and trade-offs between reproduction and vegetative growth, remain elusive, despite a long history of research. We explored how meteorological conditions determined variations in fruit production and crown cover and how remotely sensed vegetation indices, such as the enhanced vegetation index (EVI), may be used to characterize the fluctuations in fruit production. We used data for fruit production from six European tree species (Abies alba, Picea abies, Pseudotsuga menziesii, Fagus sylvatica, Quercus petraea and Q. robur) growing in monospecific stands, EVI and seasonal meteorological variables (precipitation and temperature) for 2002–2010. Weather accounted for fruit production better than EVI. Deciduous trees were more responsive to weather than evergreens, most notably to different seasonal temperatures, which were positively correlated mainly with crown cover and fruit production in deciduous species. Our results also suggested different patterns of relationships between fruit production, crown cover and weather, indicating different strategies of resource management. These patterns indicated a possible internal trade-off in evergreens, with resources allocated to either growth or reproduction. In contrast, in deciduous species we found no evidence for such a trade-off between vegetative growth and reproduction. © 2019 Elsevier B.V.

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Visible ozone-like injury, defoliation, and mortality in two Pinus uncinata stands in the Catalan Pyrenees (NE Spain)

Diaz-de-Quijano M., Kefauver S., Ogaya R., Vollenweider P., Ribas À., Peñuelas J. (2016) Visible ozone-like injury, defoliation, and mortality in two Pinus uncinata stands in the Catalan Pyrenees (NE Spain). European Journal of Forest Research. 135: 687-696.
Enlace
Doi: 10.1007/s10342-016-0964-9

Resumen:

Ozone concentrations in the Pyrenees have exceeded the thresholds for forest protection since 1994. We surveyed the severity of visible O3 injuries, crown defoliation, and tree mortality of Pinus uncinata, the dominant species in subalpine forests in this mountain range, along two altitudinal and O3 gradients in the central Catalan Pyrenees and analysed their relationships with the local environmental conditions. The severity of visible O3 injuries increased with increasing mean annual [O3] when summer water availability was high (summer precipitation/potential evapotranspiration above 0.96), whereas higher [O3] did not produce more visible injuries during drier conditions. Mean crown defoliation and tree mortality ranged between 20.4–66.4 and 0.6–29.6 %, respectively, depending on the site. Both were positively correlated with the accumulated O3 exposure during the last 5 years and with variables associated with soil–water availability, which favours greater O3 uptake by increasing stomatal conductance. The results indicate that O3 contributed to the crown defoliation and tree mortality, although further research is clearly warranted to determine the contributions of the multiple stress factors to crown defoliation and mortality in P. uncinata stands in the Catalan Pyrenees. © 2016, Springer-Verlag Berlin Heidelberg.

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Linking OMI HCHO and MODIS PRI satellite data with BVOCS emissions in NE Spain

Kefauver S.C., Filella I., Zhang C., Penuelas J. (2015) Linking OMI HCHO and MODIS PRI satellite data with BVOCS emissions in NE Spain. International Geoscience and Remote Sensing Symposium (IGARSS). 2015-November: 2661-2664.
Enlace
Doi: 10.1109/IGARSS.2015.7326360

Resumen:

Volatile organic compounds (VOCs) play several important roles on tropospheric chemical composition. Biogenic VOCs (BVOCs) are the largest source of NMVOCs (non-methane VOCs), accounting for the release of up to 10% of total C fixed by plants in photosynthesis. As isoprene is often the dominant source of atmospheric formaldehyde (HCHO) detected using satellite sensors, it is often correlated directly to satellite HCHO observations without accounting for other HCHO sources. Here we investigate the importance of quantifying monoterpene emissions when linking remotely sensed HCHO vertical columns to terrestrial BVOCs emissions at four different ecosystems in NE Spain where monoterpene-isoprene emissions ratios are known to be unusually high. Average HCHO yield for present monoterpenes was approximately 29% compared to 45% for isoprene. Including monoterpene HCHO yield contributions in total atmospheric HCHO concentrations improved correlations from R2 of 0.35 to 0.66 and R2 of 0.56 to 0.89 when comparing OMI HCHO and MODIS PRI satellite with HCHO field measurements, respectively. © 2015 IEEE.

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Remote sensing of atmospheric biogenic volatile organic compounds (BVOCs) via satellite-based formaldehyde vertical column assessments

Kefauver S.C., Filella I., Penuelas J. (2014) Remote sensing of atmospheric biogenic volatile organic compounds (BVOCs) via satellite-based formaldehyde vertical column assessments. International Journal of Remote Sensing. 35: 7519-7542.
Enlace
Doi: 10.1080/01431161.2014.968690

Resumen:

Global vegetation is intrinsically linked to atmospheric chemistry and climate, and better understanding vegetation–atmosphere interactions can allow scientists to not only predict future change patterns, but also to suggest future policies and adaptations to mediate vegetation feedbacks with atmospheric chemistry and climate. Improving global and regional estimates of biogenic volatile organic compound (BVOCs) emissions is of great interest for their biological and environmental effects and possible positive and negative feedbacks related to climate change and other vectors of global change. Multiple studies indicate that BVOCs are on the rise, and with near 20 years of global remote sensing of formaldehyde (HCHO), the immediate and dominant BVOC atmospheric oxidation product, the accurate and quantitative linkage of BVOCs with plant ecology, atmospheric chemistry, and climate change is of increasing relevance. The remote sensing of BVOCs, via HCHO in a three step process, suffers from an additive modelling error, but improvements in each of the steps have reduced this error by over a multiplication factor improvement compared to estimates without remote sensing. Differential optical absorption spectroscopy (DOAS) measurement of the HCHO slant columns from spectral absorption properties has been adapted to include the correction of numerous spectral artefacts and intricately refined for each of a series of sensors of increasing spectral and spatial resolution. Conversion of HCHO slant to HCHO vertical columns using air mass factors (AMFs) has been improved with the launch of new sensors and the incorporation of radiative transfer and chemical transport models (CTM). The critical process of linking HCHO to BVOC emissions and filtering non-biogenic emissions to explicitly quantify biogenic emissions has also greatly improved. This critical last step in down-scaling from global satellite coverage to local biogenic emissions now benefits from the increasing precision and near-explicitness of available CTMs as well as the increasing availability of global remote-sensing data sets needed to proportionally assign the HCHO column to different related biogenic (global plant functional type and land cover classifications), atmospheric (dust, aerosols, clouds, other trace gases), climate (temperature, wind, precipitation), and anthropogenic (fire, biomass burning) factors.

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Using Pinus uncinata to monitor tropospheric ozone in the Pyrenees

Kefauver S.C., Penuelas J., Ribas A., Diaz-De-Quijano M., Ustin S. (2014) Using Pinus uncinata to monitor tropospheric ozone in the Pyrenees. Ecological Indicators. 36: 262-271.
Enlace
Doi: 10.1016/j.ecolind.2013.07.024

Resumen:

Field metrics were investigated using the conifer species Pinus uncinata for the biomonitoring of tropospheric ozone in the Pyrenees of Catalonia, Spain. The Ozone Injury Index (OII) was investigated piecewise for improvement as a biomonitoring field metric for using sensitive conifer species to monitor tropospheric ozone across variable environmental conditions. The OII employs a weighted average of visual chlorotic mottling (VI), needle whorl retention (RET), needle length (LGT), and crown death (CD). Of note, VI includes subcomponents VI-Amount (% of symptomatic needles) and VI-Severity (% of chlorotic mottling on symptomatic needles) and RET includes the FWHORL subcomponent (average fraction of needles retained per whorl). All components and subcomponents of the OII correlated better to multiple year ozone exposure compared to single year ozone exposure measurements. VI-Severity and FWHORL modeled over half the variability of the three year average of ambient ozone concentrations (P < 0.0001, R2 = 0.53, RMSE = 2.73). Combining the biomonitoring metrics with GIS models related to landscape-scale variability in plant water relations resulted in considerable improvement in the ozone exposure model explanatory power (P < 0.0001, R2 = 0.90, RMSE = 1.35) including the parameters VI-Amount, VI-Severity, elevation, slope and topographic curvature. © 2013 Elsevier Ltd. All rights reserved.

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The synergy of the 0.05° (∼5km) AVHRR long-term data record (LTDR) and landsat TM archive to map large fires in the North American boreal region from 1984 to 1998

Moreno-Ruiz J.A., Garcia-Lazaro J.R., Riano D., Kefauver S.C. (2014) The synergy of the 0.05° (∼5km) AVHRR long-term data record (LTDR) and landsat TM archive to map large fires in the North American boreal region from 1984 to 1998. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing. 7: 1157-1166.
Enlace
Doi: 10.1109/JSTARS.2013.2292853

Resumen:

A Bayesian network classifier-based algorithm was applied to map the burned area (BA) in the North American boreal region using the 0.05\circ (\sim5\nbsp\hbox{km} ) Advanced Very High Resolution Radiometer (AVHRR) Long-Term Data Record (LTDR) data version 3 time series. The results showed an overall good agreement compared to reference maps (slope = 0.62;\ {R2} = 0.75 ). The study site was divided into six sub-regions, where south-western Canada performed the worst (slope = 0.25;\ {R2} = 0.47 ). The algorithm achieved good results as long as a year with high fire incidence was employed to train the Bayesian network, and the vegetation response to fire remained consistent across the region. Years with higher fire activity and larger fires, which were easier to detect at the LTDR spatial scale, matched the reference maps better. The LTDR postfire signal remained detectable for 6-9 years, extending opportunities to map the full fire extent with Landsat Thematic Mapper (TM). For fires larger than 1000\nbsp\hbox{km}2 , Landsat TM mapped 99%, whereas LTDR caught 69% of the reference BA reported. Landsat TM took four satellite overpasses (2 months) to map these large fires, and in some cases even until the following year, but LTDR detected them within days. Thus, results suggest that LTDR could be used to trigger the search for fires and then map their perimeter with Landsat TM. This study demonstrates an LTDR BA algorithm that could be extrapolated to other boreal regions using a similar methodology, although reference fire perimeters would be needed to train the Bayesian classifier and its thresholds. © 2008-2012 IEEE.

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Human migration, protected areas, and conservation outreach in Tanzania

Salerno J.D., Mulder M.B., Kefauver S.C. (2014) Human migration, protected areas, and conservation outreach in Tanzania. Conservation Biology. 28: 841-850.
Enlace
Doi: 10.1111/cobi.12237

Resumen:

A recent discussion debates the extent of human in-migration around protected areas (PAs) in the tropics. One proposed argument is that rural migrants move to bordering areas to access conservation outreach benefits. A counter proposal maintains that PAs have largely negative effects on local populations and that outreach initiatives even if successful present insufficient benefits to drive in-migration. Using data from Tanzania, we examined merits of statistical tests and spatial methods used previously to evaluate migration near PAs and applied hierarchical modeling with appropriate controls for demographic and geographic factors to advance the debate. Areas bordering national parks in Tanzania did not have elevated rates of in-migration. Low baseline population density and high vegetation productivity with low interannual variation rather than conservation outreach explained observed migration patterns. More generally we argue that to produce results of conservation policy significance, analyses must be conducted at appropriate scales, and we caution against use of demographic data without appropriate controls when drawing conclusions about migration dynamics. © 2014 Society for Conservation Biology.

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Using topographic and remotely sensed variables to assess ozone injury to conifers in the Sierra Nevada (USA) and Catalonia (Spain)

Kefauver S.C., Penuelas J., Ustin S. (2013) Using topographic and remotely sensed variables to assess ozone injury to conifers in the Sierra Nevada (USA) and Catalonia (Spain). Remote Sensing of Environment. 139: 138-148.
Enlace
Doi: 10.1016/j.rse.2013.07.037

Resumen:

The capacity to remotely identify impacts of ozone on conifers in California, USA and Catalonia, Spain was investigated using remote sensing and terrain-driven GIS analyses related to plant water relations and ozone uptake. The Ozone Injury Index (OII) field metric applied to Pinus ponderosa and Pinus jeffreyi in the USA and adapted to Pinus uncinata in Spain included visible chlorotic mottling, needle retention, needle length, and crown depth. Species classifications of AVIRIS and CASI hyperspectral imagery all approached 80% overall accuracy for the target bioindicator species. Remote sensing vegetation indices correlated best with longer-wavelength SWIR indices from the AVIRIS data in California, with the exception of the Photosynthetic Reflectance Index (PRI) correlation with the OII Visual Component (OIIVI), which was also the highest direct correlation in Catalonia. In Catalonia, the OIIVI alone and its subparts correlated better with the CASI data than with the full OII, namely the PRI (R2=0.28, p=0.0044 for OIIVI-amount and R2=0.33 and p=0.0016 for OIIVI-severity). Stepwise regression models of ozone injury developed using remote sensing indices combined with terrain-derived GIS variables were significant for OII in California (R2=0.59, p<0.0001) and in Catalonia (R2=0.68, p<0.0001 for OIIVI). Multiple regression models of ozone injury including a three year average of O3 exposure were significant both with imaging spectroscopy indices alone (R2=0.56, p<0.0001) and with topographic variables added (R2=0.77, p<0.0001) in Catalonia. Applying the multivariate models to image classifications could provide useful maps useful for ozone impact monitoring but requires further validation before being considered operational. © 2013 Elsevier Inc.

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Ecosystemic and biospheric interactions with carbon cycle

Peñuelas J, Filella I, Estiarte M, Ogaya R, Llusià J, Sardans J, Jump A, Carnicer J, Rico L, Garbulsky M, Coll M, Díaz de Quijano M, Seco R, Rivas-Ubach A, Kefauver S, Barbeta A, Achoategui A, Mejía-Chang M, Gallardo A, Farre G, Fernández M, Terradas J (2012) Ecosystemic and biospheric interactions with carbon cycle. In Carbon dioxide budget: processes and tendencies symposium. Universitat Politècnica de Catalunya, May 23-25.

Applications of hyperspectral remote sensing and GIS for assessing forest health and air pollution

Kefauver S.C., Penuelas J., Ustin S.L. (2012) Applications of hyperspectral remote sensing and GIS for assessing forest health and air pollution. International Geoscience and Remote Sensing Symposium (IGARSS). : 3379-3382.
Enlace
Doi: 10.1109/IGARSS.2012.6350696

Resumen:

The objective of this project is the assessment of air pollution impacts on conifer health in the Sierra Nevada of California, USA and the Pyrenees of Catalonia, Spain using remote sensing indices of forest health in conjunction with GIS analyses of the variability various stressors across natural landscape gradients. The Ozone Injury Index (OII) field metric applied to P. ponderosa and P. jeffreyi in the USA and adapted to P. uncinata in Spain included chlorotic mottling, needle retention, needle length, and crown depth. Species-level classifications of AVIRIS and CASI hyperspectral imagery were all near 80% overall accuracy for the target bioindicator species. Combining remote sensing indices with GIS variables related to microsite ozone uptake variability produced improved regressions for Catalonia (R2=0.68, p<0.0001) and California (R2=0.56, p<0.0001). Multiple regression models for the ozone injury visual component (VI) alone performed much better than the full OII in Catalonia combining the remote sensing index PRI and a three year average of ambient ozone (R2=0.56, p<0.0001) and better still when including GIS variables (R2=0.77, p<0.0001). © 2012 IEEE.

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