{"type": "FeatureCollection", "features": [{"id": "10.1007/s11104-022-05447-9", "type": "Feature", "geometry": null, "properties": {"updated": "2026-05-25T16:14:53Z", "type": "Journal Article", "created": "2022-05-24", "title": "Soil-tree-atmosphere CH4 flux dynamics of boreal birch and spruce trees during spring leaf-out", "description": "Abstract Aims

Studies on tree CH4 exchange in boreal forests regarding seasonality and role of tree canopies are rare. We aimed to quantify the contribution of boreal trees to the forest CH4 budget during spring leaf-out and to reveal the role of microbes in the CH4 exchange.

Methods

Methane fluxes of downy birch and Norway spruce (Betula pubescens and Picea abies) growing on fen and upland sites were measured together with soil CH4 flux, environmental variables and microbial abundances involved in the CH4 cycle. Tree CH4 fluxes were studied from three stem heights and from shoots.

Results

The trees emitted CH4 with higher stem emissions detected from birch and higher shoot emissions from spruce. The stem CH4 emissions from birches at the fen were high (mean 45\uffc2\uffa0\uffc2\uffb5g\uffc2\uffa0m\uffe2\uff88\uff922\uffc2\uffa0h\uffe2\uff88\uff921), decreasing with stem height. Their dynamics followed soil temperature, suggesting the emitted CH4 originated from methanogenic activity, manifested in high mcrA gene copy numbers, in the peat soil. Methanogens were below the quantification limit in the tree tissues. Upscaled tree CH4 emissions accounted for 22% of the total CH4 emissions at the fen.

Conclusions

The variation in stem CH4 flux between the trees and habitats is high, and the emissions from high-emitting birches increase as the spring proceeds. The lack of detection of methanogens or methanotrophs in the aboveground plant tissues suggests that these microbes did not have a significant role in the observed tree-derived fluxes. The stem-emitted CH4 from birches at the fen is presumably produced microbially in the soil.

", "keywords": ["0301 basic medicine", "570", "550", "Methanogens", "LIVING TREES", "Trees", "03 medical and health sciences", "Methanotrophs", "METHANE EMISSIONS", "SAP FLOW", "Boreal forest", "Waterlogging", "PRECURSOR", "0303 health sciences", "BIOMASS EQUATIONS", "NORWAY SPRUCE", "Forestry", "Methane fux", "15. Life on land", "Environmental sciences", "METHANOTROPHS", "13. Climate action", "RADIATION", "Methane flux", "VEGETATION", "COMMUNITIES"]}, "links": [{"href": "https://link.springer.com/content/pdf/10.1007/s11104-022-05447-9.pdf"}, {"href": "https://doi.org/10.1007/s11104-022-05447-9"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Plant%20and%20Soil", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1007/s11104-022-05447-9", "name": "item", "description": "10.1007/s11104-022-05447-9", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1007/s11104-022-05447-9"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2022-05-24T00:00:00Z"}}, {"id": "10.1016/j.agrformet.2018.11.031", "type": "Feature", "geometry": null, "properties": {"updated": "2026-05-25T16:15:21Z", "type": "Journal Article", "created": "2018-11-29", "title": "Partitioning evapotranspiration of a drip-irrigated wheat crop: Inter-comparing eddy covariance-, sap flow-, lysimeter- and FAO-based methods", "description": "Abstract A precise estimate of the evapotranspiration (ET) partitioning is fundamental for determining the crop water needs and optimizing irrigation management. The plant transpiration (T) is generally considered to be the most desirable component, while reducing the soil evaporation (E) could be one of the most important water-saving actions in semi-arid agricultural regions. Given the lack of reference method to estimate the E/T partitioning of wheat crop, this study inter-compares four different methods based on eddy covariance, sap flow and lysimetry measurements and FAO modeling. The objectives are: i) to quantify the systematic and random uncertainty in E and T observations, ii) to evaluate the partitioning ratio (T/ET) at the daily/field scale and iii) to assess the performance of the FAO model over two drip irrigated wheat fields. Results indicate that despite the small surface sensed by mini-lysimeters, the partitioning ratio is evaluated more precisely (19% relative error) with lysimetry than with the other systems (any combination of eddy covariance, lysimetry and sap flow measurements). Moreover, stem-scale T measurements from sap flow sensors are subject to representativeness issues at the field scale, and to systematic errors during water-stress and senescence periods. The lysimeter-derived partitioning ratio increases from about 0.50 to 0.85 during the growth stage and rapidly drops towards 0 during senescence. Its dynamics is found to be significantly correlated (R>0.7) with the 5-cm soil moisture. By comparing FAO simulations with observations, it is found that the FAO method overestimates T and underestimates E, while keeping satisfying ET estimates for drip irrigated wheat. This study suggests that different independent measurement techniques should be implemented to both quantify and reduce uncertainties in the T/ET ratio, and that accurate observations are still needed to improve the modeling of E/T components.", "keywords": ["FAO-56", "0106 biological sciences", "2. Zero hunger", "550", "Lysimeter", "Eddy correlation", "0207 environmental engineering", "02 engineering and technology", "15. Life on land", "01 natural sciences", "[SDU.ENVI] Sciences of the Universe [physics]/Continental interfaces", " environment", "6. Clean water", "Sap flow", "Wheat", "[SDU.STU.HY] Sciences of the Universe [physics]/Earth Sciences/Hydrology", "[SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology", "[SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces", "environment", "Evaporation-transpiration"]}, "links": [{"href": "https://doi.org/10.1016/j.agrformet.2018.11.031"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Agricultural%20and%20Forest%20Meteorology", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1016/j.agrformet.2018.11.031", "name": "item", "description": "10.1016/j.agrformet.2018.11.031", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1016/j.agrformet.2018.11.031"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2019-02-01T00:00:00Z"}}, {"id": "10.1016/j.agwat.2017.04.005", "type": "Feature", "geometry": null, "properties": {"updated": "2026-05-25T16:15:23Z", "type": "Journal Article", "created": "2017-04-20", "title": "A simple and alternative approach based on reference evapotranspiration and leaf area index for estimating tree transpiration in semi-arid regions", "description": "Abstract The present work aims to develop a simple approach relating normalized daily sap flow (liters per unit of leaf area) and daily reference evapotranspiration (ET 0 ) (mm/day). Two methods (FAO-Penman-Monteith (FAO-PM) and Hargreaves-Samani (HARG)) of the calculation of ET 0 were tested in order to examine their impact on the established relationships. The data sets used for developing this approach are taken over well irrigated orchards from three experimental sites (olive trees, cv. \u201c Olea europaea L .\u201d, olive trees, cv. \u201c Arbequino \u201d and citrus trees cv. \u201c Clementine Afourar \u201d) conducted in the Tensift region around Marrakech (center of Morocco) and one experimental site (pecan orchard, cv. \u201c Carya illinoinensis, Wangenh. K. Koch\u201d ) conducted in the Yaqui Valley, northwest of Mexico). The results showed that the normalized daily sap flow was linearly correlated with ET 0 (mm per day) calculated by FAO-PM method. The coefficient of determination (R 2 ) and the slope of this linear regression varied between 0.71 and 0.97 and between 0.30 and 0.35, respectively, depending on the type of orchards. For HARG method, the relationship between both terms is also linear but with more discrepancy (R 2 \u00a0=\u00a00.7). This was somehow expected since this method is known to underestimate ET 0 values in the semi-arid areas. Afterward, the validation of the developed linear relationship was performed over an olive orchard (\u201c Olea europaea L .\u201d) where the measurements of sap flow were available for another cropping season (2004). The scatter plot between the normalized measured and estimated sap flow based on FAO-PM method reveals a very good agreement (slope\u00a0=\u00a01, and RMSE\u00a0=\u00a00.14\u00a0L/m 2 leaf area). However, for the estimation of normalized sap flow based on HARG method, the correlation is relatively more scattered (slope\u00a0=\u00a00.95, and RMSE\u00a0=\u00a00.35\u00a0L/m 2 leaf area). A further validation was performed using the measurements of evapotranspiration (ET) by eddy correlation system and the results showed that the correlation between normalized measured ET and estimated normalized sap flow is best when using FAO-PM method (RMSE\u00a0=\u00a00.33\u00a0L/m 2 leaf area) for estimating ET 0 than when using HARG method (RMSE\u00a0=\u00a00.51\u00a0L/m 2 leaf area). Finally, the performance of the developed approach was compared to the traditional dual crop coefficient scheme for estimating plant transpiration. Cross-comparison of these two approaches with the measurements data gave satisfactory results with an average value of RMSE equal to about 0.37\u00a0mm/day for both approaches.", "keywords": ["2. Zero hunger", "0106 biological sciences", "Semi-arid", "Sap flow", "Leaf area index", "0401 agriculture", " forestry", " and fisheries", "Reference evapotranspiration", "04 agricultural and veterinary sciences", "Tree orchards", "15. Life on land", "01 natural sciences", "Transpiration"]}, "links": [{"href": "https://doi.org/10.1016/j.agwat.2017.04.005"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Agricultural%20Water%20Management", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1016/j.agwat.2017.04.005", "name": "item", "description": "10.1016/j.agwat.2017.04.005", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1016/j.agwat.2017.04.005"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2017-07-01T00:00:00Z"}}, {"id": "10.1111/2041-210X.14392", "type": "Feature", "geometry": null, "properties": {"updated": "2026-05-25T16:18:32Z", "type": "Journal Article", "created": "2024-08-07", "title": "Sap Flow Analyzer: A tool to standardize sap flow estimation and scaling to whole\u2010tree water use using the HFD method", "description": "Abstract

Sap flow measurements are fundamental to understanding water use in trees and could aid in predicting climate change effects on forest function. Deriving knowledge from such measurements requires empirical calibrations and upscaling methods to translate thermometric recordings to tree water use. Here, we developed a user\uffe2\uff80\uff90friendly open\uffe2\uff80\uff90source application, the Sap Flow Analyzer (SFA), which estimates sap flow rates and tree water use from the heat field deformation (HFD) instruments.

The SFA incorporates four key features to ensure maximum accuracy and reproducibility of sap flow estimates: diagnosis diagrams to assess data patterns visually, regression models implemented to increase accuracy when estimating K (the main HFD parameter), three approaches to upscale sap flow rates to whole\uffe2\uff80\uff90tree water use and visualization of the input parameters' uncertainty. Thirteen participants were given three raw datasets and assigned data processing tasks using the SFA user guide, from estimating sapwood depth to scaling sap flow rates to whole\uffe2\uff80\uff90tree water use to assess the reproducibility and applicability of the SFA.

Participants' results were reasonably consistent and independent of their background in using the SFA, R, or HFD method. The results showed lower variability for high flow rates (SD: mean 1% vs. 10%). K estimates and sapwood depth differentiation were the primary sources of variability, which in turn was mainly caused by the user's chosen scaling method.

The SFA provides an easy way to visualize and process sap flow and tree water use data from HFD measurements. It is the first free and open software tool for HFD users. The ability to trace analysis steps ensures reproducibility, increasing transparency and consistency in data processing. Developing tools such as the SFA and masked trials are essential for more precise workflows and improved quality and comparability of HFD sap flow datasets.

Sap flow measurements are fundamental to understanding water use in trees and could aid in predicting climate change effects on forest function. Deriving knowledge from such measurements requires empirical calibrations and upscaling methods to translate thermometric recordings to tree water use. Here, we developed a user\uffe2\uff80\uff90friendly open\uffe2\uff80\uff90source application, the Sap Flow Analyzer (SFA), which estimates sap flow rates and tree water use from the heat field deformation (HFD) instruments.

The SFA incorporates four key features to ensure maximum accuracy and reproducibility of sap flow estimates: diagnosis diagrams to assess data patterns visually, regression models implemented to increase accuracy when estimating K (the main HFD parameter), three approaches to upscale sap flow rates to whole\uffe2\uff80\uff90tree water use and visualization of the input parameters' uncertainty. Thirteen participants were given three raw datasets and assigned data processing tasks using the SFA user guide, from estimating sapwood depth to scaling sap flow rates to whole\uffe2\uff80\uff90tree water use to assess the reproducibility and applicability of the SFA.

Participants' results were reasonably consistent and independent of their background in using the SFA, R, or HFD method. The results showed lower variability for high flow rates (SD: mean 1% vs. 10%). K estimates and sapwood depth differentiation were the primary sources of variability, which in turn was mainly caused by the user's chosen scaling method.

The SFA provides an easy way to visualize and process sap flow and tree water use data from HFD measurements. It is the first free and open software tool for HFD users. The ability to trace analysis steps ensures reproducibility, increasing transparency and consistency in data processing. Developing tools such as the SFA and masked trials are essential for more precise workflows and improved quality and comparability of HFD sap flow datasets.

0.7) with the 5-cm soil moisture. By comparing FAO simulations with observations, it is found that the FAO method overestimates T and underestimates E, while keeping satisfying ET estimates for drip irrigated wheat. This study suggests that different independent measurement techniques should be implemented to both quantify and reduce uncertainties in the T/ET ratio, and that accurate observations are still needed to improve the modeling of E/T components.", "keywords": ["FAO-56", "2. Zero hunger", "0106 biological sciences", "550", "Lysimeter", "Eddy correlation", "0207 environmental engineering", "02 engineering and technology", "15. Life on land", "01 natural sciences", "[SDU.ENVI] Sciences of the Universe [physics]/Continental interfaces", " environment", "6. Clean water", "Sap flow", "Wheat", "[SDU.STU.HY] Sciences of the Universe [physics]/Earth Sciences/Hydrology", "[SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology", "[SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces", "environment", "Evaporation-transpiration"]}, "links": [{"href": "https://doi.org/2902175533"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Agricultural%20and%20Forest%20Meteorology", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "2902175533", "name": "item", "description": "2902175533", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/2902175533"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2019-02-01T00:00:00Z"}}], "links": [{"rel": "self", "type": "application/geo+json", "title": "This document as GeoJSON", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=Sap+flow&f=json", "hreflang": "en-US"}, {"rel": "alternate", "type": "text/html", "title": "This document as HTML", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=Sap+flow&f=html", "hreflang": "en-US"}, {"rel": "collection", "type": "application/json", "title": "Collection URL", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main", "hreflang": "en-US"}, {"type": "application/geo+json", "rel": "first", "title": "items (first)", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=Sap+flow&", "hreflang": "en-US"}, {"rel": "last", "type": "application/geo+json", "title": "items (last)", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=Sap+flow&offset=7", "hreflang": "en-US"}], "numberMatched": 7, "numberReturned": 7, "distributedFeatures": [], "timeStamp": "2026-05-25T21:21:37.763596Z"}