Pub Date : 2024-11-20DOI: 10.1016/j.agrformet.2024.110287
Charlotta Håkansson, Per-Ola Hedwall, Martin Karl-Friedrich Bader, Monika Strömgren, Magnus Axelsson, Johan Bergh
Late-rotation fertilization of Norway spruce stands is a frequently used management tool in Fennoscandia to increase timber yields. Meanwhile, the growing demand for renewable resources has sparked great interest in earlier and repeated fertilizer application but it remains unclear how this affects carbon dioxide (CO2) fluxes in the understory, especially forest floor respiration (Rff). This study investigated the effects of forest fertilization on Rff and net forest floor exchange (NFFE) in young, nitrogen (N) limited Norway spruce stands in southern Sweden. In a short-term dose experiment, Rff and NFFE were recorded during 2016 after varying doses of N (0, 150, 300, or 450 kg ha-1 of N, hereafter N0, N150, N300, N450) were added to circular, 3-m-diameter plots in April. In a second, long-term experiment, two stand-level fertilizer applications with 150 kg ha-1 of N on each occasion were performed in 2014 and 2016 and Rff was measured at semi-regular intervals from mid-2013 to the end of 2017. In the dose experiment, fertilization increased Rff by 23 %, 81 % and 55 % in the N150, N300 and N450 treatments, respectively. Under well-lit conditions, the N300 and N450 treatments significantly enhanced photosynthetic CO2 uptake of the forest floor vegetation by 97 % and 66 %, respectively, while the N150 treatment had no significant effect. The results of the long-term experiment indicate an initial stimulation of Rff, but this effect was transient. Our findings imply that fertilization in young Norway spruce stands, using the N150 dose (the typical dose used in Swedish forestry), may cause a transient burst in Rff that is far outweighed by nutrient-driven increases in forest floor photosynthesis under favourable light conditions prior to canopy closure.
{"title":"Forest fertilization transiently increases soil CO2 efflux in young Norway spruce stands in Sweden","authors":"Charlotta Håkansson, Per-Ola Hedwall, Martin Karl-Friedrich Bader, Monika Strömgren, Magnus Axelsson, Johan Bergh","doi":"10.1016/j.agrformet.2024.110287","DOIUrl":"https://doi.org/10.1016/j.agrformet.2024.110287","url":null,"abstract":"Late-rotation fertilization of Norway spruce stands is a frequently used management tool in Fennoscandia to increase timber yields. Meanwhile, the growing demand for renewable resources has sparked great interest in earlier and repeated fertilizer application but it remains unclear how this affects carbon dioxide (CO<sub>2</sub>) fluxes in the understory, especially forest floor respiration (<em>R</em><sub>ff</sub>). This study investigated the effects of forest fertilization on <em>R</em><sub>ff</sub> and net forest floor exchange (NFFE) in young, nitrogen (N) limited Norway spruce stands in southern Sweden. In a short-term dose experiment, <em>R</em><sub>ff</sub> and NFFE were recorded during 2016 after varying doses of N (0, 150, 300, or 450 kg ha<sup>-1</sup> of N, hereafter N0, N150, N300, N450) were added to circular, 3-m-diameter plots in April. In a second, long-term experiment, two stand-level fertilizer applications with 150 kg ha<sup>-1</sup> of N on each occasion were performed in 2014 and 2016 and <em>R</em><sub>ff</sub> was measured at semi-regular intervals from mid-2013 to the end of 2017. In the dose experiment, fertilization increased <em>R</em><sub>ff</sub> by 23 %, 81 % and 55 % in the N150, N300 and N450 treatments, respectively. Under well-lit conditions, the N300 and N450 treatments significantly enhanced photosynthetic CO<sub>2</sub> uptake of the forest floor vegetation by 97 % and 66 %, respectively, while the N150 treatment had no significant effect. The results of the long-term experiment indicate an initial stimulation of <em>R</em><sub>ff</sub>, but this effect was transient. Our findings imply that fertilization in young Norway spruce stands, using the N150 dose (the typical dose used in Swedish forestry), may cause a transient burst in <em>R</em><sub>ff</sub> that is far outweighed by nutrient-driven increases in forest floor photosynthesis under favourable light conditions prior to canopy closure.","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"170 1","pages":""},"PeriodicalIF":6.2,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142673578","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-20DOI: 10.1016/j.agrformet.2024.110312
Jamie Smidt, Luise Wanner, Andreas Ibrom, HaPe Schmid, Matthias Mauder
The use of (en)closed-path Infrared Gas Analysers (IRGA) in the measurement of Eddy Covariance (EC) fluxes results in inadvertent high-frequency tube attenuation due to diffusion and mixing of sampled gas inside the tube. The application of tube heating and installation of particulate filters along the tube length also contributes to high-frequency attenuation. The goal of this research is first, to quantify the attenuation effects of different tube heating and filter configurations on CO2 and H2O fluxes. And second, to present a modified power spectral approach (PSA) based on theoretical power spectra to calculate the effective cut-off frequency fc. Measurements for each experimental configuration were performed at an Integrated Carbon Observation System (ICOS) station equipped with the standard LI-7200 enclosed-path IRGA and Gill HS-50 3D sonic anemometer. Correction factors for each dataset were determined and implemented in post-processing. We found only very small attenuation effects of CO2 fluxes between the examined configurations. In agreement with previous studies, we found attenuation worsens with increasing relative humidity rH, in the fluxes of H2O. As expected, the highest (best) fc for H2O was found in the lowest examined rH class of 45-50 % with the configuration of heating on, no filter. The lowest (worst) fc for H2O was in the highest rH class of 90-95 % with the configuration of heating off with the 7 μm filter. Our results confirm that tube attenuation effects for the standard ICOS setup are negligible for CO2 and small for H2O, depending on tube heating settings and use of particulate filters. We also show that the post-processing of attenuation effects, especially for H2O, could improve the accuracy of long-term EC measurements. We recommend that this novel approach be considered by users of datasets collected with the LI-7200 enclosed-path IRGA.
{"title":"High-frequency attenuation in eddy covariance measurements from the LI-7200 IRGA with various heating and filter configurations – a spectral correction approach","authors":"Jamie Smidt, Luise Wanner, Andreas Ibrom, HaPe Schmid, Matthias Mauder","doi":"10.1016/j.agrformet.2024.110312","DOIUrl":"https://doi.org/10.1016/j.agrformet.2024.110312","url":null,"abstract":"The use of (en)closed-path Infrared Gas Analysers (IRGA) in the measurement of Eddy Covariance (EC) fluxes results in inadvertent high-frequency tube attenuation due to diffusion and mixing of sampled gas inside the tube. The application of tube heating and installation of particulate filters along the tube length also contributes to high-frequency attenuation. The goal of this research is first, to quantify the attenuation effects of different tube heating and filter configurations on CO<sub>2</sub> and H<sub>2</sub>O fluxes. And second, to present a modified power spectral approach (PSA) based on theoretical power spectra to calculate the effective cut-off frequency <em>fc</em>. Measurements for each experimental configuration were performed at an Integrated Carbon Observation System (ICOS) station equipped with the standard LI-7200 enclosed-path IRGA and Gill HS-50 3D sonic anemometer. Correction factors for each dataset were determined and implemented in post-processing. We found only very small attenuation effects of CO<sub>2</sub> fluxes between the examined configurations. In agreement with previous studies, we found attenuation worsens with increasing relative humidity <em>rH</em>, in the fluxes of H<sub>2</sub>O. As expected, the highest (best) <em>f<sub>c</sub></em> for H<sub>2</sub>O was found in the lowest examined <em>rH</em> class of 45-50 % with the configuration of heating on, no filter. The lowest (worst) <em>f<sub>c</sub></em> for H<sub>2</sub>O was in the highest <em>rH</em> class of 90-95 % with the configuration of heating off with the 7 μm filter. Our results confirm that tube attenuation effects for the standard ICOS setup are negligible for CO<sub>2</sub> and small for H<sub>2</sub>O, depending on tube heating settings and use of particulate filters. We also show that the post-processing of attenuation effects, especially for H<sub>2</sub>O, could improve the accuracy of long-term EC measurements. We recommend that this novel approach be considered by users of datasets collected with the LI-7200 enclosed-path IRGA.","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"8 1","pages":""},"PeriodicalIF":6.2,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142679072","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-19DOI: 10.1016/j.agrformet.2024.110299
Yiwen Xu, Jean-Christophe Calvet, Bertrand Bonan
This study focused on the production of 18-year global root zone soil moisture (RZSM) by the joint land surface data assimilation using the satellite observed leaf area index (LAI) and surface soil moisture (SSM). The impact of the assimilation on RZSM, LAI, and other key surface variables was also assessed. The multilayer diffusion scheme, biomass and CO2 interactive scheme, and the simplified extended Kalman filter were applied in the model. It was found that the assimilation could effectively reduce the biases in LAI, and that the diverse regional effects on RZSM were varied with seasons, soil wetness, error covariance in the assimilation, and water transfer in the model. A downward increase of the RZSM pattern (< ∼ 0.03 m3 m-3) was found in vegetated regions with low to moderate soil wetness because of the reduced LAI by the assimilation. A general upward change of RZSM (within ∼ ±0.01 m3 m-3) was found in dry desert regions due to the assimilation of SSM. The evaluation for the central South America shows that the assimilation improved the correlation for SSM (0.9 to 0.91) and significantly reduced the mean biases of LAI (∼ 40%). Positive impacts on day/night land surface temperature (LST) were identified to be mostly through the RZSM and LST coupling, with the improvements in the range of ±1 or 2 K. The slight adverse impact of LAI over the Amazon forests had no degradations to RZSM and LST. The assessment of the impact on water, energy, and carbon cycles over France revealed that the strongest/weakest change was found in LAI (-6.3%)/deep layer soil water index (0.03%). Ecosystem respiration, sensible heat, and evapotranspiration had relatively large changes. The underlying mechanism of the impact supports the global analysis results, indicating that the joint assimilation is beneficial for drought monitoring and heatwave detection.
{"title":"The joint assimilation of satellite observed LAI and soil moisture for the global root zone soil moisture production and its impact on land surface and ecosystem variables","authors":"Yiwen Xu, Jean-Christophe Calvet, Bertrand Bonan","doi":"10.1016/j.agrformet.2024.110299","DOIUrl":"https://doi.org/10.1016/j.agrformet.2024.110299","url":null,"abstract":"This study focused on the production of 18-year global root zone soil moisture (RZSM) by the joint land surface data assimilation using the satellite observed leaf area index (LAI) and surface soil moisture (SSM). The impact of the assimilation on RZSM, LAI, and other key surface variables was also assessed. The multilayer diffusion scheme, biomass and CO<sub>2</sub> interactive scheme, and the simplified extended Kalman filter were applied in the model. It was found that the assimilation could effectively reduce the biases in LAI, and that the diverse regional effects on RZSM were varied with seasons, soil wetness, error covariance in the assimilation, and water transfer in the model. A downward increase of the RZSM pattern (< ∼ 0.03 m<sup>3</sup> m<sup>-3</sup>) was found in vegetated regions with low to moderate soil wetness because of the reduced LAI by the assimilation. A general upward change of RZSM (within ∼ ±0.01 m<sup>3</sup> m<sup>-3</sup>) was found in dry desert regions due to the assimilation of SSM. The evaluation for the central South America shows that the assimilation improved the correlation for SSM (0.9 to 0.91) and significantly reduced the mean biases of LAI (∼ 40%). Positive impacts on day/night land surface temperature (LST) were identified to be mostly through the RZSM and LST coupling, with the improvements in the range of ±1 or 2 K. The slight adverse impact of LAI over the Amazon forests had no degradations to RZSM and LST. The assessment of the impact on water, energy, and carbon cycles over France revealed that the strongest/weakest change was found in LAI (-6.3%)/deep layer soil water index (0.03%). Ecosystem respiration, sensible heat, and evapotranspiration had relatively large changes. The underlying mechanism of the impact supports the global analysis results, indicating that the joint assimilation is beneficial for drought monitoring and heatwave detection.","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"22 1","pages":""},"PeriodicalIF":6.2,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142671091","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-16DOI: 10.1016/j.agrformet.2024.110313
Renwei Chen , Jing Wang , Bin Wang , Yang Li , Rui Bai , Mingxia Huang , Zhenjiang Qu , Lu Liu
Apple is one of the globally significant perennial fruits, with high consumption driven by the demand for nutritional food diversity and population growth. There is a lack of understanding with respect to the potential consequences of climate change, particularly the impact of spring frost – a frequent agrometeorological disaster on apple yield. Here we used a process-based apple model driven by five climate models to evaluate climate change impacts and the potential adaptation potential in China's apple planting region under climate change. Our study used the process-based STICS model developed by INRAE, France, driven by five global climate models (GCMs; FGOALS–g3, GFDL–ESM4, MPI–ESM1–2–HR, MRI–ESM2–0, and UKESM1–0–LL) to evaluate the impacts of climate change including spring frost on apple yield in China's apple planting region and explore the possible adaptation strategy by increasing thermal time required to complete the phase from budbreak to first flower opening with increments of 10%, 30%, 50%, 70%, and 90% in the STICS model at frost-sensitive sites under two emission scenarios (SSP245 and SSP585) during two periods of 2050s (2040–2069) and 2080s (2070–2099). We found the robust performance of the STICS model in simulating phenology and yield of apple across China's apple planting regions. While climate change exerts a slightly positive impact on apple yields with large spatial variation in the staple apple production regions, intensified spring frost under climate change would aggravate apple yield loss. We found that delaying flowering time can increase yield by up to 10% at the frost-sensitive sites. Our results highlight the importance of effective adaptation options to reduce frost-induced apple yield loss under climate change in China's apple planting region.
{"title":"Flowering delay in apple could alleviate frost-induced yield loss under climate change in China","authors":"Renwei Chen , Jing Wang , Bin Wang , Yang Li , Rui Bai , Mingxia Huang , Zhenjiang Qu , Lu Liu","doi":"10.1016/j.agrformet.2024.110313","DOIUrl":"10.1016/j.agrformet.2024.110313","url":null,"abstract":"<div><div>Apple is one of the globally significant perennial fruits, with high consumption driven by the demand for nutritional food diversity and population growth. There is a lack of understanding with respect to the potential consequences of climate change, particularly the impact of spring frost – a frequent agrometeorological disaster on apple yield. Here we used a process-based apple model driven by five climate models to evaluate climate change impacts and the potential adaptation potential in China's apple planting region under climate change. Our study used the process-based STICS model developed by INRAE, France, driven by five global climate models (GCMs; FGOALS–g3, GFDL–ESM4, MPI–ESM1–2–HR, MRI–ESM2–0, and UKESM1–0–LL) to evaluate the impacts of climate change including spring frost on apple yield in China's apple planting region and explore the possible adaptation strategy by increasing thermal time required to complete the phase from budbreak to first flower opening with increments of 10%, 30%, 50%, 70%, and 90% in the STICS model at frost-sensitive sites under two emission scenarios (SSP245 and SSP585) during two periods of 2050s (2040–2069) and 2080s (2070–2099). We found the robust performance of the STICS model in simulating phenology and yield of apple across China's apple planting regions. While climate change exerts a slightly positive impact on apple yields with large spatial variation in the staple apple production regions, intensified spring frost under climate change would aggravate apple yield loss. We found that delaying flowering time can increase yield by up to 10% at the frost-sensitive sites. Our results highlight the importance of effective adaptation options to reduce frost-induced apple yield loss under climate change in China's apple planting region.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"360 ","pages":"Article 110313"},"PeriodicalIF":5.6,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142642872","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-16DOI: 10.1016/j.agrformet.2024.110314
Jie Kang , Haihua Shen , Yizhen Liu , Pengzhen Ma , Bo Wu , Longchao Xu , Jingyun Fang
Tree growth in forests is affected independently or jointly by drought dimensions, namely severity, timing, and duration, making the accurate modeling predictions a formidable challenge, and it still remains uncertain how trees respond to multiple dimensions of drought. Here, we quantified the dynamic response of tree growth (evaluated by resistance and resilience) to different dimensions of droughts, and their determined factors, using tree-ring data of 320 trees in 15 birch (Betula platyphylla) forests from semiarid regions across northern China, in conjunction with environmental and biological data. Our results showed that trees had the highest resistance and resilience to extreme droughts occurring in wet seasons, and had the lowest resistance and resilience to extreme droughts occurring in both dry and wet seasons (DS+WS). Surprisingly, we found a novel result that the negative effects of continuous droughts were not always more impactful than those of single droughts. Trees had similar resistance to different durations of DS+WS droughts, and showed no difference in tree resilience between single and continuous droughts when drought severity increased. Tree resistance and resilience to each dimension of droughts showed robust relationships with climatic and soil factors, but were driven by different biological traits. Tall trees with drought-sensitive leaves were the most vulnerable to droughts in dry seasons, but older trees were less resistant to droughts in wet seasons. This study highlights that multiple drought dimensions are crucial factors determining drought impacts on tree resistance and resilience, which may have a wide range of implications for predictions and uncertainty assessments of tree growth and forest management in semiarid regions.
{"title":"Drought dimensions impact birch resistance and resilience and their determining factors across semiarid forests of northern China","authors":"Jie Kang , Haihua Shen , Yizhen Liu , Pengzhen Ma , Bo Wu , Longchao Xu , Jingyun Fang","doi":"10.1016/j.agrformet.2024.110314","DOIUrl":"10.1016/j.agrformet.2024.110314","url":null,"abstract":"<div><div>Tree growth in forests is affected independently or jointly by drought dimensions, namely severity, timing, and duration, making the accurate modeling predictions a formidable challenge, and it still remains uncertain how trees respond to multiple dimensions of drought. Here, we quantified the dynamic response of tree growth (evaluated by resistance and resilience) to different dimensions of droughts, and their determined factors, using tree-ring data of 320 trees in 15 birch (<em>Betula platyphylla</em>) forests from semiarid regions across northern China, in conjunction with environmental and biological data. Our results showed that trees had the highest resistance and resilience to extreme droughts occurring in wet seasons, and had the lowest resistance and resilience to extreme droughts occurring in both dry and wet seasons (DS+WS). Surprisingly, we found a novel result that the negative effects of continuous droughts were not always more impactful than those of single droughts. Trees had similar resistance to different durations of DS+WS droughts, and showed no difference in tree resilience between single and continuous droughts when drought severity increased. Tree resistance and resilience to each dimension of droughts showed robust relationships with climatic and soil factors, but were driven by different biological traits. Tall trees with drought-sensitive leaves were the most vulnerable to droughts in dry seasons, but older trees were less resistant to droughts in wet seasons. This study highlights that multiple drought dimensions are crucial factors determining drought impacts on tree resistance and resilience, which may have a wide range of implications for predictions and uncertainty assessments of tree growth and forest management in semiarid regions.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"360 ","pages":"Article 110314"},"PeriodicalIF":5.6,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142642871","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-15DOI: 10.1016/j.agrformet.2024.110311
Junjie Li , Junji Yuan , Yanhong Dong , Deyan Liu , Huijie Zheng , Weixin Ding
Wetlands provide a huge carbon (C) sink and represent strategic areas for regulating climate change. However, extensive wetlands have been lost since 1700, primarily for conversion to cropland. Currently, few studies have comprehensively evaluated changes in C budgets and greenhouse gas (GHG) emissions following wetland conversion to cropland. Here, we measured annual carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) emissions from a Phragmites australis-dominated wetland and adjacent wetland-converted soybean cropland by combining eddy covariance and chamber methods. We included biomass removal from cropland in the full C and GHG accounting. Annually, the P. australis wetland was a substantial atmospheric CH4 source (50 ± 1 g CH4 m‒2) but strong CO2 (‒1217 ± 162 g CO2 m‒2) and weak N2O (‒0.1 kg N2O ha‒1) sinks, which collectively shaped a big C sink (‒294 ± 44 g C m‒2) and net GHG source (180 ± 164 g CO2-eq m‒2). Converting P. australis wetland to soybean cropland demolished atmospheric CO2 and N2O sinks, and formed net sources of CO2 (140 ± 149 g CO2 m‒2 yr‒1) and N2O (1.1 ± 0.2 kg N2O ha‒1 yr‒1). Meanwhile, this conversion greatly reduced CH4 emissions to 1.2 ± 0.5 g CH4 m‒2 yr‒1. Taken together, soybean cropland was a net direct atmospheric C source of 39 ± 41 g C m‒2 yr‒1, while holding a GHG budget of 203 ± 150 g CO2-eq m‒2 yr‒1. Further, grain and straw in cropland were removed during harvest, creating a C loss of 142 ± 18 g C m‒2 yr‒1, and eventually increased GHG budget to 722 ± 165 g CO2-eq m‒2 yr‒1. Consequently, the full GHG debt of wetland-cropland conversion increased by dozens of times to 542 ± 233 g CO2-eq m‒2 yr‒1, 95.8% of which attributed to biomass removal. Overall, our study contributes to growing recognition of C loss risks of wetland conversion to cropland and highlights the importance of straw return in mitigating climate impacts during agricultural activities.
湿地是巨大的碳（C）汇，是调节气候变化的战略区域。然而，自 1700 年以来，大面积的湿地已经消失，主要原因是湿地被转为耕地。目前，很少有研究全面评估了湿地转化为耕地后碳预算和温室气体（GHG）排放的变化。在此，我们结合涡度协方差法和室法，测量了一片以葭为主的湿地和相邻湿地转化为大豆耕地后每年的二氧化碳（CO2）、甲烷（CH4）和一氧化二氮（N2O）排放量。我们将耕地的生物量去除纳入了全部碳和温室气体核算。每年，P. australis湿地是大气中大量的CH4源（50 ± 1 g CH4 m-2），但却是强大的CO2汇（-1217 ± 162 g CO2 m-2）和微弱的N2O汇（-0.1 kg N2O ha-1），这共同形成了一个巨大的C汇（-294 ± 44 g C m-2）和温室气体净源（180 ± 164 g CO2-eq m-2）。将 P. australis 湿地转换为大豆耕地则破坏了大气中的 CO2 和 N2O 吸收汇，形成了 CO2（140 ± 149 g CO2 m-2 yr-1）和 N2O（1.1 ± 0.2 kg N2O ha-1 yr-1）的净源。同时，这种转换大大减少了 CH4 排放量，使其降至 1.2 ± 0.5 g CH4 m-2 yr-1。总之，大豆耕地是 39 ± 41 克 C m-2 yr-1 的大气直接碳净来源，同时保持 203 ± 150 克 CO2-eq m-2 yr-1 的温室气体预算。此外，耕地中的谷物和秸秆在收获时被移除，造成 142 ± 18 克 C m-2 yr-1 的碳损失，最终使温室气体预算增加到 722 ± 165 克 CO2-eq m-2 yr-1。因此，湿地-耕地转换的全部温室气体债务增加了数十倍，达到 542 ± 233 g CO2-eq m-2 yr-1，其中 95.8% 归因于生物量的去除。总之，我们的研究有助于人们进一步认识到湿地转化为耕地的碳损失风险，并强调了秸秆还田在农业活动中减轻气候影响的重要性。
{"title":"Impact of wetland conversion to cropland on ecosystem carbon budget and greenhouse gas emissions in Northeast China","authors":"Junjie Li , Junji Yuan , Yanhong Dong , Deyan Liu , Huijie Zheng , Weixin Ding","doi":"10.1016/j.agrformet.2024.110311","DOIUrl":"10.1016/j.agrformet.2024.110311","url":null,"abstract":"<div><div>Wetlands provide a huge carbon (C) sink and represent strategic areas for regulating climate change. However, extensive wetlands have been lost since 1700, primarily for conversion to cropland. Currently, few studies have comprehensively evaluated changes in C budgets and greenhouse gas (GHG) emissions following wetland conversion to cropland. Here, we measured annual carbon dioxide (CO<sub>2</sub>), methane (CH<sub>4</sub>), and nitrous oxide (N<sub>2</sub>O) emissions from a <em>Phragmites australis</em>-dominated wetland and adjacent wetland-converted soybean cropland by combining eddy covariance and chamber methods. We included biomass removal from cropland in the full C and GHG accounting. Annually, the <em>P. australis</em> wetland was a substantial atmospheric CH<sub>4</sub> source (50 ± 1 g CH<sub>4</sub> m<sup>‒2</sup>) but strong CO<sub>2</sub> (‒1217 ± 162 g CO<sub>2</sub> m<sup>‒2</sup>) and weak N<sub>2</sub>O (‒0.1 kg N<sub>2</sub>O ha<sup>‒1</sup>) sinks, which collectively shaped a big C sink (‒294 ± 44 g C m<sup>‒2</sup>) and net GHG source (180 ± 164 g CO<sub>2</sub>-eq m<sup>‒2</sup>). Converting <em>P. australis</em> wetland to soybean cropland demolished atmospheric CO<sub>2</sub> and N<sub>2</sub>O sinks, and formed net sources of CO<sub>2</sub> (140 ± 149 g CO<sub>2</sub> m<sup>‒2</sup> yr<sup>‒1</sup>) and N<sub>2</sub>O (1.1 ± 0.2 kg N<sub>2</sub>O ha<sup>‒1</sup> yr<sup>‒1</sup>). Meanwhile, this conversion greatly reduced CH<sub>4</sub> emissions to 1.2 ± 0.5 g CH<sub>4</sub> m<sup>‒2</sup> yr<sup>‒1</sup>. Taken together, soybean cropland was a net direct atmospheric C source of 39 ± 41 g C m<sup>‒2</sup> yr<sup>‒1</sup>, while holding a GHG budget of 203 ± 150 g CO<sub>2</sub>-eq m<sup>‒2</sup> yr<sup>‒1</sup>. Further, grain and straw in cropland were removed during harvest, creating a C loss of 142 ± 18 g C m<sup>‒2</sup> yr<sup>‒1</sup>, and eventually increased GHG budget to 722 ± 165 g CO<sub>2</sub>-eq m<sup>‒2</sup> yr<sup>‒1</sup>. Consequently, the full GHG debt of wetland-cropland conversion increased by dozens of times to 542 ± 233 g CO<sub>2</sub>-eq m<sup>‒2</sup> yr<sup>‒1</sup>, 95.8% of which attributed to biomass removal. Overall, our study contributes to growing recognition of C loss risks of wetland conversion to cropland and highlights the importance of straw return in mitigating climate impacts during agricultural activities.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"360 ","pages":"Article 110311"},"PeriodicalIF":5.6,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142637061","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-15DOI: 10.1016/j.agrformet.2024.110301
Yalin Zhai , Lei Wang , Yunlong Yao , Jia Jia , Ruonan Li , Zhibin Ren , Xingyuan He , Zhiwei Ye , Xinyu Zhang , Yuanyuan Chen , Yezhen Xu
Aboveground biomass (AGB) is a key parameter for assessing the carbon sequestration potential of urban ecosystems. However, traditional empirical models for AGB estimation often have poor transferability in urban environments, leading to overestimation or underestimation and limiting the ability to create continuous spatial maps of AGB. Recently, the relatively stable allometric relationships between forest structure and AGB have been further validated. With the increasing use of UAV remote sensing to monitor forest structural diversity (FSD) in urban areas, there is an urgent need to develop a method for quickly and accurately estimating AGB using FSD. This study focuses on an urban forestry demonstration base as the research area, aiming to establish an allometric growth model based on FSD to estimate AGB, grounded in the power-law relationship between forest structure and AGB. By systematically defining FSD, integrating UAV-LiDAR and multispectral data, and performing regression analysis, allometric modeling, model comparison, and accuracy assessment of extracted indicators, we thoroughly explored the optimal parameter combinations and estimation accuracy for estimating urban forest AGB using the FSD allometric model. The results show that combining FSD indicators through allometric relationships can improve AGB estimation accuracy to 80 % (R2b=0.80, RMSEb=2.79 kg/m2, MAEb=2.19 kg/m2), surpassing models that use only simplified FSD indicators (R2b=0.63). Additionally, the proposed method captures nonlinear relationships and complex interactions better than traditional MLR, avoiding the overfitting that can occur with RF and XGBoost. This study confirms that allometric relationships with FSD indicators can be used for AGB prediction, highlighting the biological and physiological significance of FSD. It provides an alternative solution for rapid and large-scale AGB assessment in Urban forest.
{"title":"Spatially continuous estimation of urban forest aboveground biomass with UAV-LiDAR and multispectral scanning: An allometric model of forest structural diversity","authors":"Yalin Zhai , Lei Wang , Yunlong Yao , Jia Jia , Ruonan Li , Zhibin Ren , Xingyuan He , Zhiwei Ye , Xinyu Zhang , Yuanyuan Chen , Yezhen Xu","doi":"10.1016/j.agrformet.2024.110301","DOIUrl":"10.1016/j.agrformet.2024.110301","url":null,"abstract":"<div><div>Aboveground biomass (AGB) is a key parameter for assessing the carbon sequestration potential of urban ecosystems. However, traditional empirical models for AGB estimation often have poor transferability in urban environments, leading to overestimation or underestimation and limiting the ability to create continuous spatial maps of AGB. Recently, the relatively stable allometric relationships between forest structure and AGB have been further validated. With the increasing use of UAV remote sensing to monitor forest structural diversity (FSD) in urban areas, there is an urgent need to develop a method for quickly and accurately estimating AGB using FSD. This study focuses on an urban forestry demonstration base as the research area, aiming to establish an allometric growth model based on FSD to estimate AGB, grounded in the power-law relationship between forest structure and AGB. By systematically defining FSD, integrating UAV-LiDAR and multispectral data, and performing regression analysis, allometric modeling, model comparison, and accuracy assessment of extracted indicators, we thoroughly explored the optimal parameter combinations and estimation accuracy for estimating urban forest AGB using the FSD allometric model. The results show that combining FSD indicators through allometric relationships can improve AGB estimation accuracy to 80 % (R<sup>2</sup><sub>b</sub>=0.80, RMSE<sub>b</sub>=2.79 kg/m<sup>2</sup>, MAE<sub>b</sub>=2.19 kg/m<sup>2</sup>), surpassing models that use only simplified FSD indicators (R<sup>2</sup><sub>b</sub>=0.63). Additionally, the proposed method captures nonlinear relationships and complex interactions better than traditional MLR, avoiding the overfitting that can occur with RF and XGBoost. This study confirms that allometric relationships with FSD indicators can be used for AGB prediction, highlighting the biological and physiological significance of FSD. It provides an alternative solution for rapid and large-scale AGB assessment in Urban forest.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"360 ","pages":"Article 110301"},"PeriodicalIF":5.6,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142637059","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-14DOI: 10.1016/j.agrformet.2024.110302
A. Picornell , L. Caspersen , E. Luedeling
Global temperatures are increasing due to human-driven climate change, with notable implications for the flowering phenology of many forest tree species. Modelling the thermal requirements of these species is critical for projecting the impacts of climate change on forests and for developing appropriate adaptation strategies. Fitting models to phenological observations requires long time series of data, but such data are scarce. Researchers would benefit from combining databases from different locations to fit a single model. The aims of this study are to model the thermal requirements for flowering of the most relevant angiosperm tree species in central Europe and to determine if the accuracy of the models can be improved by limiting the geographic spread of the calibration data. To this end, we fitted the PhenoFlex phenology modelling framework using various subsets of records from the Pan-European Phenology database, which were paired with local temperature data. We used all available data for five species (Acer platanoides, Alnus glutinosa, Betula pendula, Corylus avellana and Fraxinus excelsior) to fit general thermal requirement models. We also fitted models using subsets of the dataset, limiting the calibration sets to data from climatically homogeneous regions and different geographical extents. The general models had average mean absolute errors of 8.51–15.15 days, indicating that they are effective in forecasting flowering onset for central Europe. Predictions did not improve when fitting models with data from temperature-homogeneous areas or from within small geographical extents. These findings suggest that fitting several models to cover parts of an extensive region does not necessarily perform better than fitting a single model for the whole region. This implies that including data from different locations within central Europe when calibrating models would increase the size of calibration datasets without causing a significant increase in model errors. This may help alleviate problems of data scarcity.
{"title":"The influence of calibration data diversity on the performance of temperature-based spring phenology models for forest tree species in Central Europe","authors":"A. Picornell , L. Caspersen , E. Luedeling","doi":"10.1016/j.agrformet.2024.110302","DOIUrl":"10.1016/j.agrformet.2024.110302","url":null,"abstract":"<div><div>Global temperatures are increasing due to human-driven climate change, with notable implications for the flowering phenology of many forest tree species. Modelling the thermal requirements of these species is critical for projecting the impacts of climate change on forests and for developing appropriate adaptation strategies. Fitting models to phenological observations requires long time series of data, but such data are scarce. Researchers would benefit from combining databases from different locations to fit a single model. The aims of this study are to model the thermal requirements for flowering of the most relevant angiosperm tree species in central Europe and to determine if the accuracy of the models can be improved by limiting the geographic spread of the calibration data. To this end, we fitted the PhenoFlex phenology modelling framework using various subsets of records from the Pan-European Phenology database, which were paired with local temperature data. We used all available data for five species (<em>Acer platanoides, Alnus glutinosa, Betula pendula, Corylus avellana</em> and <em>Fraxinus excelsior</em>) to fit general thermal requirement models. We also fitted models using subsets of the dataset, limiting the calibration sets to data from climatically homogeneous regions and different geographical extents. The general models had average mean absolute errors of 8.51–15.15 days, indicating that they are effective in forecasting flowering onset for central Europe. Predictions did not improve when fitting models with data from temperature-homogeneous areas or from within small geographical extents. These findings suggest that fitting several models to cover parts of an extensive region does not necessarily perform better than fitting a single model for the whole region. This implies that including data from different locations within central Europe when calibrating models would increase the size of calibration datasets without causing a significant increase in model errors. This may help alleviate problems of data scarcity.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"360 ","pages":"Article 110302"},"PeriodicalIF":5.6,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142609787","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-14DOI: 10.1016/j.agrformet.2024.110300
Yuan Yao , Shu-Miao Shu , Jian Feng , Pei Wang , Hao Jiang , Xiao-Dan Wang , Sheng Zhang
Tree radial growth records both ontogenetic growth trends and environmental information. Although the former is usually excluded from climate-growth analyses, its gradual changes have a more profound effect on forest carbon sequestration. Elucidating the kinetic mechanism behind this intrinsic trend will greatly improve our understanding and prediction of climate-growth relationships. The iterative growth model (IGM) and its extensions link organism growth, lifespan, and respiration, providing important insights into this trend. Here, we extended the IGM to the tree-ring scale (IGMR) and used tree-ring width datasets across the Northern Hemisphere to analyse the constraints of tree ontogenetic growth trends on radial growth rate (along the radius gradient). On this basis, we further elucidated the convergence and differentiation of these growth trends across different climate types and clades. The results showed that: (i) ontogenetic growth trends of trees cause the radial growth rate to follow a typical unimodal pattern along the radius gradient. (ii) This unimodal pattern is a function of tree radial size, metabolic exponent, and maintenance metabolic rate, constraining the response of tree radial growth to climate. (iii) Ontogenetic growth trends result in an inherent trade-off between tree radial growth rate and lifespan. In conclusion, different growth drivers do not alter the constraining effect of tree size on radial growth. Ontogenetic growth trends should be considered in future studies of climate-growth relationships.
{"title":"Convergence and differentiation of tree radial growth in the Northern Hemisphere","authors":"Yuan Yao , Shu-Miao Shu , Jian Feng , Pei Wang , Hao Jiang , Xiao-Dan Wang , Sheng Zhang","doi":"10.1016/j.agrformet.2024.110300","DOIUrl":"10.1016/j.agrformet.2024.110300","url":null,"abstract":"<div><div>Tree radial growth records both ontogenetic growth trends and environmental information. Although the former is usually excluded from climate-growth analyses, its gradual changes have a more profound effect on forest carbon sequestration. Elucidating the kinetic mechanism behind this intrinsic trend will greatly improve our understanding and prediction of climate-growth relationships. The iterative growth model (IGM) and its extensions link organism growth, lifespan, and respiration, providing important insights into this trend. Here, we extended the IGM to the tree-ring scale (IGMR) and used tree-ring width datasets across the Northern Hemisphere to analyse the constraints of tree ontogenetic growth trends on radial growth rate (along the radius gradient). On this basis, we further elucidated the convergence and differentiation of these growth trends across different climate types and clades. The results showed that: (i) ontogenetic growth trends of trees cause the radial growth rate to follow a typical unimodal pattern along the radius gradient. (ii) This unimodal pattern is a function of tree radial size, metabolic exponent, and maintenance metabolic rate, constraining the response of tree radial growth to climate. (iii) Ontogenetic growth trends result in an inherent trade-off between tree radial growth rate and lifespan. In conclusion, different growth drivers do not alter the constraining effect of tree size on radial growth. Ontogenetic growth trends should be considered in future studies of climate-growth relationships.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"360 ","pages":"Article 110300"},"PeriodicalIF":5.6,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142609983","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-13DOI: 10.1016/j.agrformet.2024.110298
Weiqiang Dou , Bo Xiao , Tadeo Saez-Sandino , Manuel Delgado-Baquerizo
Vascular plants and biocrusts are highly vulnerable to climate change in drylands wherein they control carbon (C) cycling. In drylands, these organisms are known to thrive alone or coexisting with each other. Yet, how multiple combinations of biocrusts and vascular plants influence C cycling remains poorly understood. Here, we conducted a mesocosm field experiment in the Chinese Loess Plateau to investigate the influence of six contrasting microsites (bare soil, biocrust, shrub alone, shrub with biocrust, grass alone, and grass with biocrust) on ecosystem C fluxes, including changes in net ecosystem exchange (NEE), ecosystem respiration (Re), and gross primary productivity (GPP). We also analyzed the influence of environmental factors (e.g., water and solar radiation) on ecosystem C fluxes across different microsites. Finally, the annual (2022.6–2023.6) NEE was simulated and estimated based on a random forest model to quantify the contributions (net C uptake or emissions) of biocrusts and vascular plants and their coexistence to C budgets in drylands. Our results showed that biocrusts and vascular plants largely regulate C fluxes in this dryland, and more importantly, that the manner in which these biotic components are combined, strongly influence the outcomes for C fluxes. In particular, we showed that microsites of biocrusts, vascular plants, and their coexistence increased GPP and Re by 1.2–6.1, 1.5–56.2, and 1.1–50.0 times, respectively, compared to bare soil microsite. All these microsites supported a net C uptake (–0.31 to –10.84 μmol m–2 s–1) except from bare soil, which was net C emission (+1.39 μmol m–2 s–1). However, we also found that compared to vascular plant microsites, biocrust-vascular plant coexistence reduced NEE, Re, and GPP by 21 %–29 % (closer to zero), 39 %–40 %, and 12 %–33 % respectively, suggesting some sort of competition among biotic components. Also, annual NEE was 37 %–159 % (closer to zero) lower at biocrust-vascular plant coexistence compared to biocrusts or vascular plants thriving alone. Correlation analysis results showed that temporal variation in C fluxes of biocrusts, vascular plants, and their coexistence were mainly driven by soil water content and photosynthetically active radiation. In summary, our work showed that vascular plants and biocrusts are key drivers of C cycling in this dryland, and further provide novel insights that considering the different biotic components of these drylands alone and in combination is critical to finetune our measurements for C fluxes in a context of climate change.
{"title":"Coexistence of vascular plants and biocrusts under changing climates and their influence on ecosystem carbon fluxes","authors":"Weiqiang Dou , Bo Xiao , Tadeo Saez-Sandino , Manuel Delgado-Baquerizo","doi":"10.1016/j.agrformet.2024.110298","DOIUrl":"10.1016/j.agrformet.2024.110298","url":null,"abstract":"<div><div>Vascular plants and biocrusts are highly vulnerable to climate change in drylands wherein they control carbon (C) cycling. In drylands, these organisms are known to thrive alone or coexisting with each other. Yet, how multiple combinations of biocrusts and vascular plants influence C cycling remains poorly understood. Here, we conducted a mesocosm field experiment in the Chinese Loess Plateau to investigate the influence of six contrasting microsites (bare soil, biocrust, shrub alone, shrub with biocrust, grass alone, and grass with biocrust) on ecosystem C fluxes, including changes in net ecosystem exchange (NEE), ecosystem respiration (<em>R</em><sub>e</sub>), and gross primary productivity (GPP). We also analyzed the influence of environmental factors (e.g., water and solar radiation) on ecosystem C fluxes across different microsites. Finally, the annual (2022.6–2023.6) NEE was simulated and estimated based on a random forest model to quantify the contributions (net C uptake or emissions) of biocrusts and vascular plants and their coexistence to C budgets in drylands. Our results showed that biocrusts and vascular plants largely regulate C fluxes in this dryland, and more importantly, that the manner in which these biotic components are combined, strongly influence the outcomes for C fluxes. In particular, we showed that microsites of biocrusts, vascular plants, and their coexistence increased GPP and <em>R</em><sub>e</sub> by 1.2–6.1, 1.5–56.2, and 1.1–50.0 times, respectively, compared to bare soil microsite. All these microsites supported a net C uptake (–0.31 to –10.84 μmol m<sup>–2</sup> s<sup>–1</sup>) except from bare soil, which was net C emission (+1.39 μmol m<sup>–2</sup> s<sup>–1</sup>). However, we also found that compared to vascular plant microsites, biocrust-vascular plant coexistence reduced NEE, <em>R</em><sub>e</sub>, and GPP by 21 %–29 % (closer to zero), 39 %–40 %, and 12 %–33 % respectively, suggesting some sort of competition among biotic components. Also, annual NEE was 37 %–159 % (closer to zero) lower at biocrust-vascular plant coexistence compared to biocrusts or vascular plants thriving alone. Correlation analysis results showed that temporal variation in C fluxes of biocrusts, vascular plants, and their coexistence were mainly driven by soil water content and photosynthetically active radiation. In summary, our work showed that vascular plants and biocrusts are key drivers of C cycling in this dryland, and further provide novel insights that considering the different biotic components of these drylands alone and in combination is critical to finetune our measurements for C fluxes in a context of climate change.</div></div>","PeriodicalId":50839,"journal":{"name":"Agricultural and Forest Meteorology","volume":"360 ","pages":"Article 110298"},"PeriodicalIF":5.6,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142601136","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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