Water requirements of short rotation poplar coppice: Experimental and modelling analyses across Europe

Fischer, Milan; Zenone, Terenzio; Trnka, Miroslav; Orság, Matěj; Montagnani, Leonardo; Ward, Eric J.; Tripathi, Abhishek Mani; Hlavinka, Petr; Seufert, G.; Žalud, Zdeněk; King, John S.; Ceulemans, R.

doi:10.1016/j.agrformet.2017.12.079

Cited by 23 publications

(11 citation statements)

References 91 publications

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“…the transferability of the original model and in particular, soil conditions together with related silvicultural practices. Indeed, among the essential requirements for the successful development of poplar plantations, is a well-drained soil with an easy access to water [60,61]. To satisfy this condition, tillage practices are applied in the driest regions (i.e.…”

Section: Effect Of Transfer Direction: Case Of the Poplar Classmentioning

confidence: 99%

From local to global: A transfer learning-based approach for mapping poplar plantations at national scale using Sentinel-2

Hamrouni

Paillassa

Chéret

et al. 2021

ISPRS Journal of Photogrammetry and Remote Sensing

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Reliable estimates of poplar plantations area are not available at the French national scale due to the unsuitability and low update rate of existing forest databases for this short-rotation species. While supervised classification methods have been shown to be highly accurate in mapping forest cover from remotely sensed images, their performance depends to a great extent on the labelled samples used to build the models. In addition to their high acquisition cost, such samples are often scarce and not fully representative of the variability in class distributions. Consequently, when classification models are applied to large areas with high intra-class variance, they generally yield poor accuracies. In this paper, we propose the use of active learning (AL) to efficiently adapt a classifier trained on a source image to spatially distinct target images with minimal labelling effort and without sacrificing classification performance. The adaptation consists in actively adding to the initial local model, new relevant training samples from other areas, in a cascade that iteratively improves the generalisation capabilities of the classifier, leading to a global model tailored to different areas. This active selection relies on uncertainty sampling to directly focus on the most informative pixels for which the algorithm is the least certain of their class labels. Experiments conducted on Sentinel-2 time series showed that when the same number of training samples was used, active learning outperformed passive learning (random sampling) by up to 5% of overall accuracy and up to 12% of class F-score. In addition, and depending on the class considered, the random sampling required up to 50% more samples to achieve the same performance of an active learning-based model. Moreover, the results demonstrate the suitability of the derived global model to accurately map poplar plantations among other tree species with overall accuracy values up to 14% higher than those obtained with local models. The proposed approach paves the way for national-scale mapping in an operational context.

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Section: Effect Of Transfer Direction: Case Of the Poplar Classmentioning

confidence: 99%

From local to global: A transfer learning-based approach for mapping poplar plantations at national scale using Sentinel-2

Hamrouni

Paillassa

Chéret

et al. 2021

ISPRS Journal of Photogrammetry and Remote Sensing

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“…Studying a belt and alley system in Australia, Ward et al (2012) found an EBC between 67 % and 80 % over the time period of 6 months. Fischer et al (2018) reported on the water requirements of three short rotation poplar stands and found a mean long-term energy balance closure of 82 % at a site in Italy, an EBC of 91 % or 95 % at a site in the Czech Republic, and an EBC of 69 % at a site in Belgium.…”

Section: Ebc From Ec and Ec-lcmentioning

confidence: 99%

“…Currently, little is known about the system-scale water use of heterogeneously shaped short rotation alley cropping agroforestry systems in Germany. The majority of the previous studies focused on the water use of short rotation coppices, but not on AF systems (Bloemen et al, 2016;Fischer et al, 2013Fischer et al, , 2018Schmidt-Walter et al, 2014). Fischer et al (2013) and Zenone et al (2015) observed a lower annual sum of evapotranspiration over a poplar SRC in the Czech Republic and in Belgium, compared to the annual sum of evapotranspiration over a reference grassland.…”

Section: Introductionmentioning

confidence: 98%

Evapotranspiration over agroforestry sites in Germany

Markwitz¹,

Knohl²,

Siebicke³

2020

Biogeosciences

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Abstract. In the past few years, the interest in growing crops and trees for bioenergy production has increased. One agricultural practice is the mixed cultivation of fast-growing trees and annual crops or perennial grasslands on the same piece of land, which is referred to as one type of agroforestry (AF). The inclusion of tree strips into the agricultural landscape has been shown – on the one hand – to lead to reduced wind speeds and higher carbon sequestration above ground and in the soil. On the other hand, concerns have been raised about increased water losses to the atmosphere via evapotranspiration (ET). Therefore, we hypothesise that short rotation coppice agroforestry systems have higher water losses to the atmosphere via ET compared to monoculture (MC) agriculture without trees. In order to test the hypothesis, the main objective was to measure the actual evapotranspiration of five AF systems in Germany and compare those to five monoculture systems in the close vicinity of the AF systems. We measured actual ET at five AF sites in direct comparison to five monoculture sites in northern Germany in 2016 and 2017. We used an eddy covariance energy balance (ECEB) set-up and a low-cost eddy covariance (EC-LC) set-up to measure actual ET over each AF and each MC system. We conducted direct eddy covariance (EC) measurement campaigns with approximately 4 weeks' duration for method validation. Results from the short-term measurement campaigns showed a high agreement between ETEC-LC and ETEC, indicated by slopes of a linear regression analysis between 0.86 and 1.3 (R2 between 0.7 and 0.94) across sites. Root mean square errors of LEEC-LC vs. LEEC (where LE is the latent heat flux) were half as small as LEECEB vs. LEEC, indicating a superior agreement of the EC-LC set-up with the EC set-up compared to the ECEB set-up. With respect to the annual sums of ET over AF and MC, we observed small differences between the two land uses. We interpret this as being an effect of compensating the small-scale differences in ET next to and in between the tree strips for ET measurements on the system scale. Most likely, the differences in ET rates next to and in between the tree strips are of the same order of magnitude, but of the opposite sign, and compensate each other throughout the year. Differences between annual sums of ET from the two methods were of the same order of magnitude as differences between the two land uses. Compared to the effect of land use and different methods on ET, we found larger mean evapotranspiration indices (∑ET/∑P) across sites for a drier than normal year (2016) compared to a wet year (2017). This indicates that we were able to detect differences in ET due to different ambient conditions with the applied methods, rather than the potentially small effect of AF on ET. We conclude that agroforestry has not resulted in an increased water loss to the atmosphere, indicating that agroforestry in Germany can be a land-use alternative to monoculture agriculture without trees.

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“…At the same time, these stripes can accumulate dry biomass fuel and thereby become corridors for fire movement, which suggests additional considerations concerning management and species selection in fire-sensitive areas. While fast-growing grass and SRC species can be effective for flood mitigation, the effects on water availability in dry areas should also be considered, given their high water demands 28,29 . Thus, to provide a more comprehensive, and precise, understanding of the benefits and trade-offs of strategic perennialization, it is necessary to study a broad range of environmental aspects on a smaller scale with higher resolution.…”

Section: Resultsmentioning

confidence: 99%

Strategic deployment of riparian buffers and windbreaks in Europe can co-deliver biomass and environmental benefits

Englund

Börjesson

Mola‐Yudego

et al. 2021

Commun Earth Environ

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Within the scope of the new Common Agricultural Policy of the European Union, in coherence with other EU policies, new incentives are developed for farmers to deploy practices that are beneficial for climate, water, soil, air, and biodiversity. Such practices include establishment of multifunctional biomass production systems, designed to reduce environmental impacts while providing biomass for food, feed, bioenergy, and other biobased products. Here, we model three scenarios of large-scale deployment for two such systems, riparian buffers and windbreaks, across over 81,000 landscapes in Europe, and quantify the corresponding areas, biomass output, and environmental benefits. The results show that these systems can effectively reduce nitrogen emissions to water and soil loss by wind erosion, while simultaneously providing substantial environmental co-benefits, having limited negative effects on current agricultural production. This kind of beneficial land-use change using strategic perennialization is important for meeting environmental objectives while advancing towards a sustainable bioeconomy.

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Water requirements of short rotation poplar coppice: Experimental and modelling analyses across Europe

Cited by 23 publications

References 91 publications

From local to global: A transfer learning-based approach for mapping poplar plantations at national scale using Sentinel-2

From local to global: A transfer learning-based approach for mapping poplar plantations at national scale using Sentinel-2

Evapotranspiration over agroforestry sites in Germany

Strategic deployment of riparian buffers and windbreaks in Europe can co-deliver biomass and environmental benefits

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