Oscar Pérez-Priego- Ph.D
- Distinguished Researcher at University of Córdoba
Oscar Pérez-Priego
- Ph.D
- Distinguished Researcher at University of Córdoba
About
81
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Introduction
Current institution
Additional affiliations
January 2014 - present
September 2006 - February 2011
Publications
Publications (81)
Tree growth responses to climate depend on factors including species, site-specific conditions, and stand structure, which can be amended by the implementation of forest management practices. Among silvicultural techniques, thinning is known to proficiently enhance forest growth and physiology in seasonally dry environments, influencing tree functi...
Context
Remote sensing has shown potential to provide accurate and real-time information on grassland forage quality, crucial for the management of livestock systems. However, there are still uncertainties that must be considered to make models reliable and practical. A source of discrepancy regards the measurement unit describing forage quality va...
Excessive tree mortality is a global concern and remains poorly understood as it is a complex phenomenon. We lack global and temporally continuous coverage on tree mortality data. Ground-based observations on tree mortality, e.g., derived from national inventories, are very sparse, not standardized and not spatially explicit. Earth observation data...
Co‐occurring plants show wide variation in their hydraulic and photosynthetic traits. Here, we extended ‘least‐cost’ optimality theory to derive predictions for how variation in key hydraulic traits potentially affects the cost of acquiring and using water in photosynthesis and how this, in turn, should drive variation in photosynthetic traits.
We...
Integrating climate change concerns into forest management strategies remains challenging. Among management strategies, thinning has been proven to alter major components underlying the carbon and water cycles over the short term. However, the functional adaptability of managed forests to cope with long-term drought remains unclear. This study aims...
Remote sensing capabilities to monitor evergreen broadleaved vegetation are limited by the low temporal variability in the greenness signal. With canopy greenness computed from digital repeat photography (PhenoCam), we investigated how canopy greenness related to seasonal changes in leaf age and traits as well as variation of trees’ water fluxes (c...
Fundamental axes of variation in plant traits result from trade-offs between costs and benefits of resource-use strategies at the leaf scale. However, it is unclear whether similar trade-offs propagate to the ecosystem level. Here, we test whether trait correlation patterns predicted by three well-known leaf- and plant-level coordination theories –...
Forest plantations are more vulnerable to the stress induced by biotic and abiotic factors than are naturally regenerated forests. These effects can be aggravated by a lack of management in large reforestation areas, and thinning could, therefore, help trees to reduce dieback and tree mortality related to drought. We address this question using a d...
Increasing intensity and frequency of droughts are leading to forest dieback, growth decline and tree mortality worldwide. Reducing tree-to-tree competition for water resources is a primary goal for adaptive climate silviculture strategies, particularly in reforested areas with high planting density. Yet, we need better insights into the role of st...
Fundamental axes of variation in plant traits result from trade-offs between costs and benefits of resource-use strategies at the leaf scale. However, it is unclear whether trade-offs and optimality principles in functional traits of leaves are conserved at the ecosystem level. We tested three well-known leaf- and plant-level coordination theories...
The input of liquid water to terrestrial ecosystems is composed of rain and non-rainfall water (NRW). The latter comprises dew, fog, and the adsorption of atmospheric vapor on soil particle surfaces. Although NRW inputs can be relevant to support ecosystem functioning in seasonally dry ecosystems, they are understudied, being relatively small, and...
Remote sensing capabilities to monitor evergreen broadleaved vegetation are limited by the low temporal variability in the greenness signal. With canopy greenness computed from digital repeat photography (PhenoCam), we investigated how canopy greenness related to seasonal changes in leaf age and traits as well as variation of trees’ water fluxes (c...
Background and aims:
Despite the critical role of woody tissues in determining net carbon exchange of terrestrial ecosystems, relatively little is known regarding the drivers of sapwood and bark respiration.
Methods:
Using one of the most comprehensive wood respiration datasets to date (82 species from Australian rainforest, savanna and temperat...
Enclosure-based techniques are widely used in physiological studies and largely constitute the foundation of our current understanding of the processes controlling the plant–soil–atmosphere gas exchange, such as photosynthesis, respiration, and evaporation. Back in the 1970s, chamber systems became highly developed to overcome the difficulties in i...
The input of liquid water to terrestrial ecosystems is composed of rain and non-rainfall water input (NRWI). The latter comprises dew, fog, and adsorption of atmospheric vapor on soil particle surfaces. Although NRWIs can be relevant to support ecosystem functioning in seasonally dry ecosystems, they are understudied, being relatively small, and th...
The leaf economics spectrum1,2 and the global spectrum of plant forms and functions³ revealed fundamental axes of variation in plant traits, which represent different ecological strategies that are shaped by the evolutionary development of plant species². Ecosystem functions depend on environmental conditions and the traits of species that comprise...
Plant transpiration links physiological responses of vegetation to water supply and demand with hydrological, energy, and carbon budgets at the land–atmosphere interface. However, despite being the main land evaporative flux at the global scale, transpiration and its response to environmental drivers are currently not well constrained by observatio...
Nutrient availability, especially of nitrogen (N) and phosphorus (P), is of major importance for every organism and at a larger scale for ecosystem functioning and productivity. Changes in nutrient availability and potential stoichiometric imbalance due to anthropogenic nitrogen deposition might lead to nutrient deficiency or alter ecosystem functi...
The coupling of radiative transfer, energy balance, and photosynthesis models has brought new opportunities to characterize vegetation functional properties from space. However, these models do not accurately represent processes in ecosystems characterized by mixtures of green vegetation and senescent plant material (SPM), in particular grasslands....
Analyzing tree structural features and capturing their temporal dynamic is challenging but crucial for determining key state variables related to plant function, management practices, and aboveground vegetation stocks. Terrestrial laser scanning (TLS) provides a mean for representing those key variables in three-dimensional space and through time....
We apply and compare three widely applicable methods for estimating ecosystem transpiration
(T) from eddy covariance (EC) data across 251 FLUXNET sites globally. All
three methods are based on the coupled water and carbon relationship, but they differ
in assumptions and parameterizations. Intercomparison of the three daily T estimates
shows high co...
We apply and compare three widely applicable methods for estimating ecosystem transpiration (T) from eddy covariance (EC) data across 251 FLUXNET sites globally. All three methods are based on the coupled water and carbon relationship, but they differ in assumptions and parameterizations. Intercomparison of the three daily T estimates shows high co...
Soil CO2 efflux is the second-largest carbon flux in terrestrial ecosystems. Its feedback to climate determines model predictions of the land carbon sink, which is crucial to understanding the future of the earth system. For understanding and quantification, however, observations by the most widely applied chamber measurement method need to be aggr...
Anthropogenic nitrogen (N) deposition and resulting differences in ecosystem N and phosphorus (P) ratios are expected to impact photosynthetic capacity, i.e. maximum gross primary productivity (GPPmax). However, the interplay between N and P availability with other critical resources on seasonal dynamics of ecosystem productivity remain largely unk...
![TSEB Sensible Heat model scheme (adapted from Kustas and Anderson [9]).](publication/339881484/figure/fig2/AS:11431281211398212@1702405639498/TSEB-Sensible-Heat-model-scheme-adapted-from-Kustas-and-Anderson-9_Q320.jpg)
The thermal-based two-source energy balance (TSEB) model has accurately simulated energy fluxes in a wide range of landscapes with both remote and proximal sensing data. However, tree-grass ecosystems (TGE) have notably complex heterogeneous vegetation mixtures and dynamic phenological characteristics presenting clear challenges to earth observatio...
The dynamics of biochemical processes in terrestrial ecosystems are tightly coupled to local meteorological conditions. Understanding these interactions is an essential prerequisite for predicting, e.g. the response of the terrestrial carbon cycle to climate change. However, many empirical studies in this field rely on correlative approaches and on...
Abstract. Remote Sensing (RS) has traditionally provided estimates of key biophysical properties controlling light interaction with the canopy (e.g., chlorophyll content ( C <sub>ab</sub>) or leaf area index (LAI)). However, recent and upcoming developments in hyperspectral RS are expected to lead to a new generation of products such as vegetation...
Semi-arid grasslands and other ecosystems combine green and senescent leaves featuring different biochemical and optical properties, as well as functional traits. Knowing how these properties vary is necessary to understand the functioning of these ecosystems. However, differences between green and senescent leaves are not considered in recent mode...
Sun-Induced fluorescence at 760 nm (F760) is increasingly being used to predict gross primary production (GPP) through light use efficiency (LUE) modeling, even though the mechanistic processes that link the two are not well understood. We analyzed the effect of nitrogen (N) and phosphorous (P) availability on the processes that link GPP and F760 i...
Evaporation (E) and transpiration (T) respond differently to ongoing changes in climate, atmospheric composition, and land use. It is difficult to partition ecosystem-scale evapotranspiration (ET) measurements into E and T, which makes it difficult to validate satellite data and land surface models. Here, we review current progress in partitioning...
The most recent efforts to provide remote sensing (RS) estimates of plant function rely on the combination of Radiative Transfer Models (RTM) and Soil-Vegetation-Atmosphere Transfer (SVAT) models, such as the Soil-Canopy Observation Photosynthesis and Energy fluxes (SCOPE) model. In this work we used ground spectro-radiometric and chamber-based CO...
The thermal-based Two-Source Energy Balance (TSEB) model has successfully simulated energy fluxes in a wide range of landscapes. However, tree-grass ecosystems (TGE) have notably complex heterogenous vegetation mixtures and dynamic phenological characteristics presenting clear challenges to earth observation and modeling methods. Therefore, the TSE...
Local meteorological conditions and biospheric activity are tightly coupled. Understanding these links is an essential prerequisite for predicting the Earth system under climate change conditions. However, many empirical studies on the interaction between the biosphere and the atmosphere are based on correlative approaches that are not able to dedu...
Soil CO2 efflux is the second largest carbon flux in terrestrial ecosystems. Its feedback to climate determines model predictions of the land carbon sink, which is crucial to understanding the future of the earth system. For understanding and quantification, however, observations by the most widely applied chamber measurement method need to be aggr...
The authors modify the schematic plots in their article [...]
Evaporation (E) and transpiration (T) respond differently to ongoing changes in climate, atmospheric composition, and land use. Our ability to partition evapotranspiration (ET) into E and T is limited at the ecosystem scale, which renders the validation of satellite data and land surface models incomplete. Here, we review current progress in partit...
The ratio of CO2 efflux to O2 influx (ARQ, apparent respiratory quotient) in tree stems is expected to be 1.0 for carbohydrates, the main substrate supporting stem respiration. In previous studies of stem fluxes, ARQ values below 1.0 were observed and hypothesized to indicate retention of respired carbon within the stem. Here, we demonstrate that s...
![Fig. 5. Correlations of half hourly NEE [μmol m − ² s-1 ] between...](profile/Yunpeng-Luo-2/publication/326588969/figure/fig4/AS:652296119652353@1532530922866/Correlations-of-half-hourly-NEE-mmol-m-s-1-between-towers-for-spring-2014-March_Q320.jpg)
To understand what is driving spatial flux variability within a savanna type ecosystem in central Spain, data of three co-located eddy covariance (EC) towers in combination with hyperspectral airborne measurements and footprint analysis were used. The three EC systems show consistent, and unbiased mass and energy fluxes. Nevertheless, instantaneous...
Eddy covariance (EC) provides ecosystem-scale estimates of photosynthesis (Ph) and evapotranspiration (ET; the sum of plant transpiration [T] and evaporation [Es]). Separating ET into its components is becoming necessary for linking plant-water use strategies to environmental variability. Based on optimality principles, a data-model based approach...
Tree-grass ecosystems are widely distributed. However, their phenology has not yet been fully characterized. The technique of repeated digital photographs for plant phenology monitoring (hereafter referred as PhenoCam) provide opportunities for long-term monitoring of plant phenology, and extracting phenological transition dates (PTDs, e.g., start...
The ratio of CO2 efflux to O2 influx (ARQ, apparent respiratory quotient) in tree stems is expected to be 1.0 for carbohydrates, the main substrate supporting stem respiration. In previous studies of stem fluxes, ARQ values below 1.0 were observed and hypothesized to indicate retention of respired carbon within the stem. Here, we demonstrate that s...
We evaluated the underlying causes of differences between latent heat (LE) fluxes measured with two enclosed-path eddy covariance systems (EC) at two measurement levels and independent estimates in an open oak-tree grass savannah over almost one year. Estimates of LE of the well-stablished underlying grass by replicated weighable tension-controlled...
Sun‐induced fluorescence ( SIF ) in the far‐red region provides a new noninvasive measurement approach that has the potential to quantify dynamic changes in light‐use efficiency and gross primary production ( GPP ). However, the mechanistic link between GPP and SIF is not completely understood.
We analyzed the structural and functional factors cont...
Research on the subterranean CO2 dynamics has focused individually on either surface soils or bedrock cavities, neglecting the interaction of both systems as a whole. In this regard, the vadose-zone contains CO2-enriched air (ca.5% by volume) in the first meters, and its exchange with the atmosphere can represent from 10 to 90% of total ecosystem C...
Occasional rain events occur over the dry season in semiarid ecosystems and cause immediate, large increases in the net CO2 efflux which gradually decrease over a few days following the rain event. In a semiarid grassland located in SE Spain, these precipitation pulses represent only 7% of dry season length but provoked approximately 40% of the car...
This study investigates the performances of different optical indices to estimate gross primary production (GPP) of herbaceous stratum in a Mediterranean savanna with different nitrogen (N) and phosphorous (P) availability. Sun-induced chlorophyll fluorescence yield computed at 760 nm (Fy760), scaled photochemical reflectance index (sPRI), MERIS te...
The consistency of eddy-covariance measurements is often evaluated in terms of the degree of energy balance closure. Even over sloping terrain, instrumentation for measuring energy balance components is commonly installed horizontally, i.e. perpendicular to the geo-potential gradient. Subsequently, turbulent fluxes of sensible and latent heat are r...
This study investigates the performances of different optical indices to estimate gross primary production (GPP) of herbaceous stratum in a Mediterranean savanna with different Nitrogen (N) and Phosphorous (P) availability. Sun-induced chlorophyll Fluorescence yield computed at 760 nm (Fy760), scaled-photochemical reflectance index (sPRI), MERIS te...
Climate change may alter soil ecosystem functioning, as assessed via the net carbon ecosystem exchange (NEE) with the atmosphere, assumed to be related to the balance of biological processes of photosynthesis (gross primary production) and ecosystem respiration. Recent studies in carbonate ecosystems show a contribution of subsoil ventilation (VE)...
The accurate representation of terrestrial CO2 uptake (GPP) using Monteith’s approach requires a frequent and site-specific parameterization of the model inputs. In this work, an optimization of this approach has been carried out by adjusting the inputs (fAPAR, PAR and ε) for the study area, peninsular Spain, a typical Mediterranean region. The dai...
Aims
Gas exchange measurements on individual plants depend largely on chamber systems, and uncertainties and corrections in current flux calculation procedures require further assessment.
Methods
We present a practical study with novel methods for analyses of flux uncertainties in an original chamber design excluding soil fluxes and allowing simult...
Understanding the environmental and biotic drivers of respiration at the ecosystem level is a prerequisite to further improve scenarios of the global carbon cycle. In this study we investigated the relevance of physiological phenology, defined as seasonal changes in plant physiological properties, for explaining the temporal dynamics of ecosystem r...
Determining the spatial and temporal distribution of terrestrial gross primary production (GPP) is a critical step in closing the Earth's carbon budget. Dynamical global vegetation models (DGVMs) provide mechanistic insight into GPP variability but diverge in predicting the response to climate in poorly investigated regions. Recent advances in the...
Climate change may alter ecosystem functioning, as assessed via the net carbon (C) exchange (NEE) with the atmosphere, composed of the biological processes photosynthesis (GPP) and respiration (R
eco). In addition, in semi-arid Mediterranean ecosystems, a significant fraction of respired CO2 is stored in the vadose zone and emitted afterwards by su...
The accurate assessment of respiration by woody vegetation, still a challenge in plant productivity models, is generally a problem of correctly scaling-up the process from organs to the whole plant. We used a large (41.6 m(3)), canopy chamber to enclose mature olive trees and to measure aboveground respiration (R (ag) ) under natural environmental...
Knowledge of all the mechanisms and processes involved in soil CO2 emissions is essential to close the global carbon cycle. Apart from molecular diffusion, the main phys- ical component of such CO2 exchange is soil ventilation. Ad- vective CO2 transport, through soil or snow, has been corre- lated with the wind speed, friction velocity or pressure...
Use of permanent beds combined with controlled traffic (PB) has been proposed as an alternative planting system for reducing soil erosion and compaction while increasing soil organic carbon (SOC) in irrigated, annual-crop based systems in Mediterranean conditions. The objective of this study was to characterise, in space (beds and furrows with and...
In semiarid climates, water is the fundamental factor determining
ecosystem productivity and thereby the capacity for carbon
sequestration. Increased water use efficiency (WUE), the ratio of carbon
dioxide assimilation (canopy photosynthesis, Pc) to water transpired
(canopy evaporation, Ec), is assumed to be an adaptive strategy for
sclerophyll shr...
Wetlands accumulate a significant portion of the global soil carbon pool
and are considered important carbon sinks. However, it is still unknown
whether wetlands will convert from long-term carbon sinks to sources due
to global warming and other anthropogenic effects. The eddy covariance
technique is one of the most commonly used methods worldwide...
Knowledge of mechanisms and processes underlying in CO2 emissions
soil-atmosphere is essential to improve the understanding of the global
carbon cycle. The main abiotic driver in the CO2 exchange is soil
ventilation. This advective transport through porous media has been
correlated with quasi-static pressure (p) gradients and turbulent winds.
Here...
The measurement of canopy photosynthesis and transpiration is crucial to
understand the carbon and water cycles, specially, in water-limited
ecosystems. When the objective is to quantify fluxes of carbon at
whole-plant level, scaling up from leaf to canopy by using multi-layer
models is always a tricky approach, because of the complexity in
obtaini...
Knowledge of all the mechanisms and processes involved in soil CO2 emissions is essential to close the global carbon cycle. Apart from molecular diffusion, the main physical component of such CO2 exchange is soil ventilation. Advective CO2 transport, through soil or snow, has been correlated with the wind speed, friction velocity or pressure (p). H...
Little information is available on carbon exchange of olive orchards despite their agronomical and ecological importance. Measurements of CO2 and water vapour exchange were performed during 2006 and 2007 with large closed chambers in an olive orchard in Cordoba (Spain) under two irrigation regimes, full and regulated deficit irrigation. Canopy assi...
Sufficient flower number and quality is a prerequisite for subsequent fruit set, and, in the case of commercial fruit crops, for fruit production. In the olive tree, Olea europaea L., flower development constitutes an extensive process which requires two to three months and includes the elongation and branching of the inflorescence axis and the for...
An initial step for achieving good fruit production is the formation of a sufficient number of flowers capable of pollination, fertilization and fruit set. We examined the influence of the time of water stress on floral development and quality by withholding water supply during successive periods from winter dormancy until flowering and initial fru...
A transient-state chamber was developed to measure canopy gas exchange of single trees in the field. The chamber, with a volume of 41.6 m3, is designed to enclose a medium-size orchard tree; chamber top and windows can be left open, causing minimum disturbance to the tree environment. Transitory closures allow simultaneous measurement of CO2 exchan...
A series of diurnal airborne campaigns were conducted over an orchard field to assess the canopy Photochemical Reflectance Index (PRI) as an indicator of water stress. Airborne campaigns over two years were conducted with the Airborne Hyperspectral Scanner (AHS) over an orchard field to investigate changes in PRI, in the Transformed Chlorophyll Abs...
A high spectral resolution spectrometer with 0.065-nm full-width half-maximum was used for collecting spectral measurements in an orchard field under three water stress treatments. The study was part of the FluorMOD project funded by the European Space Agency to develop a leaf-canopy reflectance model to simulate the effects of fluorescence. Water...
Poster presentado en el Congreso Airborne Imaging Spectroscopy Workshop, Bruges, Belgium, 7/10/2005 Methods for water stress and chlorosis detection in crops are presented using the Airborne Hyperspectral Scanner (AHS), Compact Airborne Spectrographic Imager (CASI) and the Reflective Optics System Imaging Spectrometer (ROSIS) airborne sensors. The...
2nd International Workshop on Remote Sensing of Vegetation Fluorescence, 17-19 Nov. 2004, Montreal, Canada A high spectral resolution spectrometer of 0.065 nm FWHM in the 680-770 nm range was used for collecting spectral measurements in an orchard of olive trees in Spain under 3 different water stress treatments. The measurements were conducted as...
El olivar constituye uno de los principales sistemas agrícolas en el área Mediterránea, y puede desempeñar un papel muy importante en el ciclo biogeoquímico como sumidero de gases de efecto invernadero (GEI). Sin embargo, la capacidad de fijar CO2 en diferentes condiciones ambientales por parte de las cubiertas de olivar es casi desconocida. Por ot...
Questions
Questions (2)
Both vegetation canopy characteristics and environmental conditions drive ET and weighing lysimeter are appropriated for water balance studies. However, there are some practical issues in the method when lysimeters are used in sites under grazing management. Under such conditions, animals may produce disturbances either on the lysimeter or eventually on the data. Then, fencing the lysimeter and proceed with manual clipping could be an appropriate alternative.
Have you managed lysimeters under similar conditions?
Can you give some feedbacks based on your experience?
Recent publications highlight the importance of 'abiotic contributions' to the net ecosystem carbon balance (NECB) over different Mediterranean ecosystems (Kowalski et al., 2008; Were et al., 2010; Ferlan et al., 2011; Rey et al., 2012). Some carbonate ecosystems, characterized by cracks and pores, can temporally store large amounts of CO2 below ground, that can be vented depending on meteorological conditions such as rainfall events, changes in temperature and pressure, atmospheric stability, and wind speed. The non-negligible role of subterranean (micro and macro) pores as a temporal storehouse of CO2, presumably coming from biological and/or geochemical processes, is still poorly understood, as are the main drivers controlling abiotic processes.
