Net primary productivity, allocation pattern and carbon use efficiency in an apple orchard assessed by integrating eddy covariance, biometric and continuous soil chamber measurements

Model parameterization and validation of earth–atmosphere interactions are generally performed using a single timescale (e.g., nearly instantaneous, daily, and annual), although both delayed responses and hysteretic effects have been widely recognized. The lack of consideration of these effects hampers our capability to represent them in empirical‐ or process‐based models. Here we explore, using an apple orchard ecosystem in the North of Italy as a simplified case study, how the considered timescale impacts the relative importance of the single environmental variables in explaining observed net ecosystem exchange (NEE) and evapotranspiration (ET). Using 6 years of eddy covariance and meteorological information as input data, we found a decay of the relative importance of the modeling capability of photosynthetically active radiation in explaining both NEE and ET moving from half‐hourly to seasonal timescale and an increase in the relative importance of air temperature (T) and VPD. Satellite NDVI, used as proxy of leaf development, added little improvement to overall modeling capability. Increasing the timescale, the number of variables needed for parameterization decreased (from 5 to 1), while the proportion of variance explained by the model increased (r 2 from 0.56–0.78 to 0.85–0.90 for NEE and ET respectively). The wavelet coherence and the phase analyses showed that the two variables that increased their relative importance when the scale increased (T, VPD) were not in phase at the correlation peak of both ET and NEE. This phase shift in the time domain corresponds to a hysteretic response in the meteorological variables domain. This work confirms that the model parameterization should be performed using parameters calculated at the appropriate scale. It suggests that in managed ecosystems, where the interannual variability is minimized by the agronomic practices, the use of timescales large enough to include hysteretic and delayed responses reduces the number of required input variables and improves their explanatory capacity.

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“…Details on carbon allocation and net ecosystem carbon balance can be found in Zanotelli et al. () and in Zanotelli et al. ().…”

Section: Methodsmentioning

confidence: 99%

“…In addition, they sequester carbon in perennial vegetative organs, with a turnover time of decades, or even centuries as in the case of olive trees. All these processes do not occur at the same rate across the year (Zanotelli, Montagnani, Manca, & Tagliavini, ).…”

Section: Introductionmentioning

confidence: 99%

Timescale effects on the environmental control of carbon and water fluxes of an apple orchard

Montagnani

Zanotelli

Tagliavini

et al. 2017

Ecology and Evolution

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“…A more explicit accounting of the spatial and temporal variation in LUE could improve NPP models. Furthermore, allocation patterns among compartments (leaves, stems, roots) are seldom assessed at present (Navarro et al ; Zanotelli et al ), thereby hindering accurate modelling of plant growth and yield.…”

Section: Introductionmentioning

confidence: 99%

Increased light‐use efficiency sustains net primary productivity of shaded coffee plants in agroforestry system

Charbonnier

Roupsard

Maire

et al. 2017

Plant Cell & Environment

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In agroforestry systems, shade trees strongly affect the physiology of the undergrown crop. However, a major paradigm is that the reduction in absorbed photosynthetically active radiation is, to a certain extent, compensated by an increase in light-use efficiency, thereby reducing the difference in net primary productivity between shaded and non-shaded plants. Due to the large spatial heterogeneity in agroforestry systems and the lack of appropriate tools, the combined effects of such variables have seldom been analysed, even though they may help understand physiological processes underlying yield dynamics. In this study, we monitored net primary productivity, during two years, on scales ranging from individual coffee plants to the entire plot. Absorbed radiation was mapped with a 3D model (MAESPA). Light-use efficiency and net assimilation rate were derived for each coffee plant individually. We found that although irradiance was reduced by 60% below crowns of shade trees, coffee light-use efficiency increased by 50%, leaving net primary productivity fairly stable across all shade levels. Variability of aboveground net primary productivity of coffee plants was caused primarily by the age of the plants and by intraspecific competition among them (drivers usually overlooked in the agroforestry literature) rather than by the presence of shade trees.

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“…CUE was reported to be about 0.50 in temperate forests (Waring et al 1998, DeLucia et al 2007, Zanotelli et al 2013 iForest -Biogeosciences and Forestry Fig. 4 -A comparison on mean ecosystem respiration rate estimated with nighttime data only (night) and a combining of both day-and night-time data (night+day).…”

Section: Comparison On the New Top-down N Pp And Ibp Based N Ppmentioning

confidence: 99%

Quantifying forest net primary production: combining eddy flux, inventory and metabolic theory

Tan¹,

Hughes²,

Satô³

et al. 2017

iForest

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, Ke-Ping Ma (8) Net primary production (NPP) is a central and fundamental carbon-related term in global change studies. We proposed a top-down method to quantifying forest NPP which overcomes the deficits of the traditional bottom-up method. The new top-down method combines eddy flux data, climate variables, tree inventory and metabolic theory. Our method was tested in six forests and provides reliable annual NPP estimations which are consistent with bottom-up results. Carbon use efficiency also supports this new method. Taking advantage of fine temporal resolution of our top-down method, we examined whether and confirmed NPP was well correlated with leaf area index at a seasonal scale, as suggested by past studies. The potential value of our new method as a standard NPP method is high because of the world-wide network on eddy tower and inventory plot, however further data of performance of the new method is needed to fully evaluate its performance under different conditions.

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Net primary productivity, allocation pattern and carbon use efficiency in an apple orchard assessed by integrating eddy covariance, biometric and continuous soil chamber measurements

Cited by 74 publications

References 100 publications

Timescale effects on the environmental control of carbon and water fluxes of an apple orchard

Timescale effects on the environmental control of carbon and water fluxes of an apple orchard

Increased light‐use efficiency sustains net primary productivity of shaded coffee plants in agroforestry system

Quantifying forest net primary production: combining eddy flux, inventory and metabolic theory

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