Tree mortality is a complex process that not only be affected by the various factors, such as stand and climate factors, but also the various long-term effects of the factors to each other. In this study, based on the long-term spacing trials of Chinese fir in four regions of southern China, a Bayesian network was used to model tree mortality in response to stand and climate factors, as well as comparing this approach with logistic regression and random forest method. The results showed that the Bayesian network method had the highest accuracy in predicting tree mortality. In addition, the Bayesian network approach could find the dependency in the relationship between data and provide a theoretical framework for modeling uncertainty by using probabilistic calculus and underlying graph structure. Sensitivity analysis showed relative diameter was the most important factor, and temperature was the most important climate factor. Furthermore, climate factors not only directly affected tree mortality, but also indirectly affected tree mortality through affecting relative diameter, stand density and Gini coefficient. We also found that stand competition, structural heterogeneity and age affected tree mortality under climate change, and a moderate level of competition condition and stand structure heterogeneity weakened the negative impact of climate factors on tree mortality. Old trees were more sensitive to climate change than young trees, especially under extreme climate conditions. Besides, we found that tree mortality was negatively correlated with moderate annual precipitation, winter mean minimum temperature, and stand structure (Gini), and low age, but positively correlated with low relative diameter, high density and age. The results will provide adaptive options for effective forest management of Chinese fir plantations under the backdrop of global climate change in the future.
{"title":"A Bayesian network model to disentangle the effects of stand and climate factors on tree mortality of Chinese fir plantations","authors":"Yihang Jiang, Zhen Wang, Hanyue Chen, Yuxin Hu, Yancheng Qu, Sophan Chhin, Jianguo Zhang, Xiongqing Zhang","doi":"10.3389/ffgc.2023.1298968","DOIUrl":"https://doi.org/10.3389/ffgc.2023.1298968","url":null,"abstract":"Tree mortality is a complex process that not only be affected by the various factors, such as stand and climate factors, but also the various long-term effects of the factors to each other. In this study, based on the long-term spacing trials of Chinese fir in four regions of southern China, a Bayesian network was used to model tree mortality in response to stand and climate factors, as well as comparing this approach with logistic regression and random forest method. The results showed that the Bayesian network method had the highest accuracy in predicting tree mortality. In addition, the Bayesian network approach could find the dependency in the relationship between data and provide a theoretical framework for modeling uncertainty by using probabilistic calculus and underlying graph structure. Sensitivity analysis showed relative diameter was the most important factor, and temperature was the most important climate factor. Furthermore, climate factors not only directly affected tree mortality, but also indirectly affected tree mortality through affecting relative diameter, stand density and Gini coefficient. We also found that stand competition, structural heterogeneity and age affected tree mortality under climate change, and a moderate level of competition condition and stand structure heterogeneity weakened the negative impact of climate factors on tree mortality. Old trees were more sensitive to climate change than young trees, especially under extreme climate conditions. Besides, we found that tree mortality was negatively correlated with moderate annual precipitation, winter mean minimum temperature, and stand structure (Gini), and low age, but positively correlated with low relative diameter, high density and age. The results will provide adaptive options for effective forest management of Chinese fir plantations under the backdrop of global climate change in the future.","PeriodicalId":12538,"journal":{"name":"Frontiers in Forests and Global Change","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135113005","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Introduction Thinning has a crucial impact on the carbon dynamics of forest ecosystems. The inconsistencies about the effects of thinning on carbon stocks in previous studies may be attributed to different thinning plans that designed to achieve different management goals. Methods This study focuses on Cunninghamia lanceolata as the research object and investigates three treatments: crop tree release (CTR), traditional thinning (TM), and no thinning (CK). The different thinning methods (CTR and TM) had different management objectives and selection of crop trees principle, although with the same thinning density. The short-term effects of CTR and TM treatments on tree growth and carbon storage in Cunninghamia lanceolata plantations were analyzed and compared. Results Both CTR and TM were beneficial to the growth of individual trees when compared to CK, with CTR being more beneficial. The average annual increments in DBH, TH, and volume of a single tree in CTR increased by 62.50%, 61.29%, and 74.07% higher than CK, respectively. So CTR was the best for large-diameter timber yield, which was 77.40% higher than CK, whereas CK had a higher proportion of medium- and small-diameter timber yield. However, CTR had an insignificant short-term boosting effect on stand volume, and its timber volume was considerably higher than that in TM treatment, but not as high as in CK. Therefore, the carbon storage in the tree layer, litter, and different soil layers under different treatments showed that CTR and TM were significantly lower than CK. And the total carbon storage in the three treatments showed that CK > CTR > TM, with CTR showing a 13.07% higher than TM. On the contrary, thinning could effectively improve understory vegetation carbon storage. The carbon storage in the herb and shrub layers under CTR increased by 47.77% and 183.44%, respectively, compared to CK. Discussion Although thinning could significantly promote the growth of individual trees and understory vegetation, their total carbon storage in the short term was lower than that in CK. CTR showed a higher carbon sequestration and sink capacity than TM. It suggests that CTR, as a special type of thinning method, should be encouraged to selected because it has the chance to achieve a faster carbon sequestration rate than traditional thinning and it also can produce higher-quality timber.
{"title":"Initial effects of crop tree release and traditional thinning on productivity and carbon storage of Cunninghamia lanceolata plantation","authors":"Xianhua Zou, Ziyang Zheng, Chutong Yang, Mengjia Yang, Zhijuan Guo, Yongxin Wang, Zhijun Huang, Liqin Zhu, Liqing Xu, Kaimin Lin","doi":"10.3389/ffgc.2023.1288613","DOIUrl":"https://doi.org/10.3389/ffgc.2023.1288613","url":null,"abstract":"Introduction Thinning has a crucial impact on the carbon dynamics of forest ecosystems. The inconsistencies about the effects of thinning on carbon stocks in previous studies may be attributed to different thinning plans that designed to achieve different management goals. Methods This study focuses on Cunninghamia lanceolata as the research object and investigates three treatments: crop tree release (CTR), traditional thinning (TM), and no thinning (CK). The different thinning methods (CTR and TM) had different management objectives and selection of crop trees principle, although with the same thinning density. The short-term effects of CTR and TM treatments on tree growth and carbon storage in Cunninghamia lanceolata plantations were analyzed and compared. Results Both CTR and TM were beneficial to the growth of individual trees when compared to CK, with CTR being more beneficial. The average annual increments in DBH, TH, and volume of a single tree in CTR increased by 62.50%, 61.29%, and 74.07% higher than CK, respectively. So CTR was the best for large-diameter timber yield, which was 77.40% higher than CK, whereas CK had a higher proportion of medium- and small-diameter timber yield. However, CTR had an insignificant short-term boosting effect on stand volume, and its timber volume was considerably higher than that in TM treatment, but not as high as in CK. Therefore, the carbon storage in the tree layer, litter, and different soil layers under different treatments showed that CTR and TM were significantly lower than CK. And the total carbon storage in the three treatments showed that CK > CTR > TM, with CTR showing a 13.07% higher than TM. On the contrary, thinning could effectively improve understory vegetation carbon storage. The carbon storage in the herb and shrub layers under CTR increased by 47.77% and 183.44%, respectively, compared to CK. Discussion Although thinning could significantly promote the growth of individual trees and understory vegetation, their total carbon storage in the short term was lower than that in CK. CTR showed a higher carbon sequestration and sink capacity than TM. It suggests that CTR, as a special type of thinning method, should be encouraged to selected because it has the chance to achieve a faster carbon sequestration rate than traditional thinning and it also can produce higher-quality timber.","PeriodicalId":12538,"journal":{"name":"Frontiers in Forests and Global Change","volume":"1 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135411520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2023-10-23DOI: 10.3389/ffgc.2023.1275392
Paul W. Richardson, Peter H. Cafferata, Salli F. Dymond, Elizabeth T. Keppeler, Joseph W. Wagenbrenner, John A. Whiting
Given the high costs of constructing, maintaining, monitoring, and sampling paired watersheds, it is prudent to ask “Are paired watershed studies still worth the effort?” We present a compilation of 90 North American paired watershed studies and use examples from the Caspar Creek Experimental Watersheds to contend that paired watershed studies are still worth the effort and will continue to remain relevant in an era of big data and short funding cycles. We offer three reasons to justify this assertion. First, paired watersheds allow for watershed-scale experiments that have produced insights into hydrologic processes, water quality, and nutrient cycling for over 100 years. Paired watersheds remain an important guide to inform best management practices for timber harvesting and other land-management concerns. Second, paired watersheds can produce long climate, streamflow, and water quality records because sites are frequently maintained over the course of multiple experiments or long post-treatment periods. Long-term datasets can reveal ecological surprises, such as changes in climate-streamflow relationships driven by slow successional processes. Having multiple watershed records helps identify the cause of these changes. Third, paired watersheds produce data that are ideal for developing and testing hydrologic models. Ultimately, the fate of paired watersheds is up to the scientific community and funding agencies. We hope that their importance continues to be recognized.
{"title":"Past and future roles of paired watersheds: a North American inventory and anecdotes from the Caspar Creek Experimental Watersheds","authors":"Paul W. Richardson, Peter H. Cafferata, Salli F. Dymond, Elizabeth T. Keppeler, Joseph W. Wagenbrenner, John A. Whiting","doi":"10.3389/ffgc.2023.1275392","DOIUrl":"https://doi.org/10.3389/ffgc.2023.1275392","url":null,"abstract":"Given the high costs of constructing, maintaining, monitoring, and sampling paired watersheds, it is prudent to ask “Are paired watershed studies still worth the effort?” We present a compilation of 90 North American paired watershed studies and use examples from the Caspar Creek Experimental Watersheds to contend that paired watershed studies are still worth the effort and will continue to remain relevant in an era of big data and short funding cycles. We offer three reasons to justify this assertion. First, paired watersheds allow for watershed-scale experiments that have produced insights into hydrologic processes, water quality, and nutrient cycling for over 100 years. Paired watersheds remain an important guide to inform best management practices for timber harvesting and other land-management concerns. Second, paired watersheds can produce long climate, streamflow, and water quality records because sites are frequently maintained over the course of multiple experiments or long post-treatment periods. Long-term datasets can reveal ecological surprises, such as changes in climate-streamflow relationships driven by slow successional processes. Having multiple watershed records helps identify the cause of these changes. Third, paired watersheds produce data that are ideal for developing and testing hydrologic models. Ultimately, the fate of paired watersheds is up to the scientific community and funding agencies. We hope that their importance continues to be recognized.","PeriodicalId":12538,"journal":{"name":"Frontiers in Forests and Global Change","volume":"42 234","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135405337","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Introduction Forest and grassland are the two main carbon-collecting terrestrial ecosystems, and detecting their solar-induced chlorophyll fluorescence (SIF) enables evaluation of their photosynthetic intensity and carbon-collecting capacity. Since SIF that is retrieved directly from satellite observations suffers from low spatial resolution, discontinuity, or low temporal resolution, some vegetation indexes (VIs) and meteorological factors are used as predictors to reconstruct SIF products. Yet, unlike VIs, certain meteorological factors feature a relatively low space resolution and their observations are not always accessible. This study aimed to explore the potential of reconstructing SIF from fewer predictors whose high-resolution observations are easily accessible. Methods A total of six forest and grassland regions across low, mid, and high latitudes were selected, and the commonly used predictors-normalized difference vegetation index (NDVI), enhanced vegetation index (EVI), and land surface temperature (LST)—were compared for their correlation with SIF. Results show that the combination of EVI and LST is more strongly correlated with SIF, but each contributed differently to SIF at differing growth stages of forest and grassland. Accordingly, we proposed the idea of a combined sampling approach that considers both location and phenological phase, to explore the extent to which time and space coverage samples' span could enlarge the disparity of EVI data in particular regions at specific growth stages. To do that, three kinds of sample combination methods were proposed: monthly regression at a global scale, seasonal regression at a regional scale, and monthly regression at a regional scale. Following this, Sentinel-3 EVI and MODIS LST data were used to reconstruct 500 m SIF in the six regions by implementing the proposed methodology. Results and discussion These results showed that the R 2 values were ≥0.90 between the reconstructed SIF and MODIS GPP (gross primary productivity), 0.70 with GOME-2 SIF and 0.77 with GOSIF, thus proving the proposed methodology could produce reliable results for reconstruction of 500 m SIF. This proposed approach, which bypasses dependence of traditional SIF reconstruction model on numerous predictors not easy to obtain, can serve as a better option for more efficient and accurate high-resolution SIF reconstructions in the future.
森林和草地是两种主要的陆地碳收集生态系统，探测它们的太阳诱导叶绿素荧光(SIF)可以评估它们的光合强度和碳收集能力。由于直接从卫星观测中获取的SIF存在低空间分辨率、不连续或低时间分辨率的问题，因此利用一些植被指数和气象因子作为预测因子来重建SIF产品。然而，与VIs不同的是，某些气象因子的空间分辨率相对较低，它们的观测结果并不总是可获得的。本研究旨在探索从更少的预测因子中重建SIF的潜力，这些预测因子的高分辨率观测结果很容易获得。方法选取低、中、高纬度地区的6个森林和草原区，比较常用预测因子归一化植被指数(NDVI)、增强植被指数(EVI)和地表温度(LST)与SIF的相关性。结果表明，EVI和LST的组合与SIF的相关性更强，但在森林和草地的不同生长阶段，它们对SIF的贡献不同。因此，我们提出了考虑地理位置和物候阶段的组合采样方法，探讨时间和空间覆盖样本跨度对特定区域特定生长阶段EVI数据差异的放大程度。为此，提出了三种样本组合方法:全球尺度的月回归、区域尺度的季节回归和区域尺度的月回归。在此基础上，利用Sentinel-3 EVI和MODIS LST数据重建了6个地区的500 m SIF。结果与讨论结果表明，重建的SIF与MODIS GPP (gross primary productivity)的r2值≥0.90，与GOME-2 SIF的r2值为0.70，与GOSIF的r2值为0.77，表明该方法可以获得可靠的500 m SIF重建结果。该方法绕过了传统SIF重建模型对众多难以获得的预测因子的依赖，可以作为未来更高效、更准确的高分辨率SIF重建的更好选择。
{"title":"Using enhanced vegetation index and land surface temperature to reconstruct the solar-induced chlorophyll fluorescence of forests and grasslands across latitude and phenology","authors":"Peipei Zhang, Haiqiu Liu, Hangzhou Li, Jianen Yao, Xiu Chen, Jinying Feng","doi":"10.3389/ffgc.2023.1257287","DOIUrl":"https://doi.org/10.3389/ffgc.2023.1257287","url":null,"abstract":"Introduction Forest and grassland are the two main carbon-collecting terrestrial ecosystems, and detecting their solar-induced chlorophyll fluorescence (SIF) enables evaluation of their photosynthetic intensity and carbon-collecting capacity. Since SIF that is retrieved directly from satellite observations suffers from low spatial resolution, discontinuity, or low temporal resolution, some vegetation indexes (VIs) and meteorological factors are used as predictors to reconstruct SIF products. Yet, unlike VIs, certain meteorological factors feature a relatively low space resolution and their observations are not always accessible. This study aimed to explore the potential of reconstructing SIF from fewer predictors whose high-resolution observations are easily accessible. Methods A total of six forest and grassland regions across low, mid, and high latitudes were selected, and the commonly used predictors-normalized difference vegetation index (NDVI), enhanced vegetation index (EVI), and land surface temperature (LST)—were compared for their correlation with SIF. Results show that the combination of EVI and LST is more strongly correlated with SIF, but each contributed differently to SIF at differing growth stages of forest and grassland. Accordingly, we proposed the idea of a combined sampling approach that considers both location and phenological phase, to explore the extent to which time and space coverage samples' span could enlarge the disparity of EVI data in particular regions at specific growth stages. To do that, three kinds of sample combination methods were proposed: monthly regression at a global scale, seasonal regression at a regional scale, and monthly regression at a regional scale. Following this, Sentinel-3 EVI and MODIS LST data were used to reconstruct 500 m SIF in the six regions by implementing the proposed methodology. Results and discussion These results showed that the R 2 values were ≥0.90 between the reconstructed SIF and MODIS GPP (gross primary productivity), 0.70 with GOME-2 SIF and 0.77 with GOSIF, thus proving the proposed methodology could produce reliable results for reconstruction of 500 m SIF. This proposed approach, which bypasses dependence of traditional SIF reconstruction model on numerous predictors not easy to obtain, can serve as a better option for more efficient and accurate high-resolution SIF reconstructions in the future.","PeriodicalId":12538,"journal":{"name":"Frontiers in Forests and Global Change","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135569547","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Introduction Climate change and land use/cover changes (LUCC) greatly influenced terrestrial carbon sequestration. Methods This study evaluated the effects of climate change and LUCC on the carbon sequestration of forest ecosystems from 1991 to 2020 in the coastal area of China using a process-based global vegetation dynamic model (IBIS). Results and discussion The results showed that temperature had an increasing trend, with a rate of 0.02 °C yr −1 ; 20.00% of the forest coverage shifted spatially but there was only a 0.31% increase in total area. The carbon sequestration amounts by plants (net primary productivity, NPP) and the net carbon budget (net ecosystem productivity, NEP) in the coastal area of China in 2020 were 666.49 and 58.45 Tg C yr −1 , respectively, which increased by 18.31% and 2509.30%, respectively, compared to the values in 1991. The increased forest ecosystem NPP and NEP were mainly due to climate change, while forest cover changes increased NPP by only 0.06% and NEP by 9.75% with a strong regional difference. The NPP showed a significant increasing trend, with a rate of 3.01 Tg C yr −1 , which was positively correlated with temperature (0.43, p < 0.01) and precipitation (0.42, p < 0.01). However, the NEP largely varied during 1991-2020 and did not show a significant correlation with precipitation or temperature. These results provide scientific guidance for the government to enact environmental protection and low-carbon land use planning policies.
气候变化和土地利用/覆被变化对陆地碳固存有很大影响。方法采用基于过程的全球植被动态模型(IBIS)，研究了1991 - 2020年中国沿海地区气候变化和土地利用/土地覆盖变化对森林生态系统固碳的影响。结果与讨论结果表明:温度呈上升趋势，升温速率为0.02°C / yr - 1;森林覆盖率有20.00%的空间变化，但总面积仅增加0.31%。2020年中国沿海地区植物固碳量(净初级生产力，NPP)和净碳收支(净生态系统生产力，NEP)分别为666.49和58.45 Tg C yr - 1，分别比1991年增加18.31%和2509.30%。森林生态系统NPP和NEP的增加主要是由于气候变化，而森林覆盖变化仅增加了NPP的0.06%和NEP的9.75%，且区域差异较大。NPP呈显著上升趋势，上升速率为3.01 Tg C yr - 1，与温度呈显著正相关(0.43,p <0.01)和降水(0.42,p <0.01)。然而，NEP在1991-2020年期间变化很大，与降水和温度没有显著相关。研究结果为政府制定环境保护和低碳土地利用规划政策提供了科学指导。
{"title":"Effects of climate change and land use/cover changes on carbon sequestration in forest ecosystems in the coastal area of China","authors":"Yanlin Zhen, Xiuying Zhang, Congguo Zhang, Qian Gao, Jiaqi Dong, Liuzhen Zhang, Xuehe Lu, Yingying Wang","doi":"10.3389/ffgc.2023.1271239","DOIUrl":"https://doi.org/10.3389/ffgc.2023.1271239","url":null,"abstract":"Introduction Climate change and land use/cover changes (LUCC) greatly influenced terrestrial carbon sequestration. Methods This study evaluated the effects of climate change and LUCC on the carbon sequestration of forest ecosystems from 1991 to 2020 in the coastal area of China using a process-based global vegetation dynamic model (IBIS). Results and discussion The results showed that temperature had an increasing trend, with a rate of 0.02 °C yr −1 ; 20.00% of the forest coverage shifted spatially but there was only a 0.31% increase in total area. The carbon sequestration amounts by plants (net primary productivity, NPP) and the net carbon budget (net ecosystem productivity, NEP) in the coastal area of China in 2020 were 666.49 and 58.45 Tg C yr −1 , respectively, which increased by 18.31% and 2509.30%, respectively, compared to the values in 1991. The increased forest ecosystem NPP and NEP were mainly due to climate change, while forest cover changes increased NPP by only 0.06% and NEP by 9.75% with a strong regional difference. The NPP showed a significant increasing trend, with a rate of 3.01 Tg C yr −1 , which was positively correlated with temperature (0.43, p &lt; 0.01) and precipitation (0.42, p &lt; 0.01). However, the NEP largely varied during 1991-2020 and did not show a significant correlation with precipitation or temperature. These results provide scientific guidance for the government to enact environmental protection and low-carbon land use planning policies.","PeriodicalId":12538,"journal":{"name":"Frontiers in Forests and Global Change","volume":"8 5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135729751","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The frequency and severity of drought events are increasing under a changing climate, trees of different stand ages respond differently to drought events, which has a great impact on the stability of forest ecosystems. In this study, we measured radial growth (RG) in cored trees from 49 forests including young stands (20–30a) and middle-aged stands (31–50a) of Pinus sylvestris var. mongolica plantations in a semi-arid area of western Liaoning, China. We evaluated the response of RG of P. sylvestris to long-term climate, and calculate three response indicators: resistance (Rt), recovery (Rc) and resilience (Rs), so as to measure the growth response of trees to drought events. Results showed that a negative correlation was detected between RG of young stands and the monthly highest temperature (MHT) in April and May. Positive correlations were found between RG of young stands and the monthly lowest temperature (MLT) across periods from September to November, when RG of young stands was also positively correlated with Palmer Drought Severity Index (PDSI) across whole-years. There was a positive correlation between RG of middle-aged stands and MLT in September, and PDSI from June to December. After the first drought event, most pine trees recovered their RG (Rc > 1, Rs > 1). However, after three consecutive drought events, Rt, Rc, and Rs of pine trees decreased significantly ( p < 0.05), and Rt and Rs were less than 1. In summary, younger pine trees are more sensitive to climate change, and spring drought is more inhibitory to growth of pine trees than high summer temperatures. Pine trees have a compensation effect after experiencing drought events, but the cumulative effect of multiple drought events will gradually offset the compensation effect of trees and eventually decline in pine tree growth, while the resistance and resilience of young stands after continuous drought events were significantly lower than those of middle-aged stands, and have a higher risk of death.
{"title":"Response of radial growth of Pinus sylvestris var. mongolica of different stand ages to climate and extreme drought events in the semi-arid region of western Liaoning, Northeast China","authors":"Ping Liu, Shiyu Hu, Hongxu Wei, Wenting He, Yiming Zhou, Yutao Wang","doi":"10.3389/ffgc.2023.1272477","DOIUrl":"https://doi.org/10.3389/ffgc.2023.1272477","url":null,"abstract":"The frequency and severity of drought events are increasing under a changing climate, trees of different stand ages respond differently to drought events, which has a great impact on the stability of forest ecosystems. In this study, we measured radial growth (RG) in cored trees from 49 forests including young stands (20–30a) and middle-aged stands (31–50a) of Pinus sylvestris var. mongolica plantations in a semi-arid area of western Liaoning, China. We evaluated the response of RG of P. sylvestris to long-term climate, and calculate three response indicators: resistance (Rt), recovery (Rc) and resilience (Rs), so as to measure the growth response of trees to drought events. Results showed that a negative correlation was detected between RG of young stands and the monthly highest temperature (MHT) in April and May. Positive correlations were found between RG of young stands and the monthly lowest temperature (MLT) across periods from September to November, when RG of young stands was also positively correlated with Palmer Drought Severity Index (PDSI) across whole-years. There was a positive correlation between RG of middle-aged stands and MLT in September, and PDSI from June to December. After the first drought event, most pine trees recovered their RG (Rc &gt; 1, Rs &gt; 1). However, after three consecutive drought events, Rt, Rc, and Rs of pine trees decreased significantly ( p &lt; 0.05), and Rt and Rs were less than 1. In summary, younger pine trees are more sensitive to climate change, and spring drought is more inhibitory to growth of pine trees than high summer temperatures. Pine trees have a compensation effect after experiencing drought events, but the cumulative effect of multiple drought events will gradually offset the compensation effect of trees and eventually decline in pine tree growth, while the resistance and resilience of young stands after continuous drought events were significantly lower than those of middle-aged stands, and have a higher risk of death.","PeriodicalId":12538,"journal":{"name":"Frontiers in Forests and Global Change","volume":"68 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135731788","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2023-10-19DOI: 10.3389/ffgc.2023.1288365
Petr Prochazka, Josef Abrham, Jaroslav Cerveny, Lukas Kobera, Petra Sanova, Daniel Benes, Julia-Maria Fink, Eliska Jiraskova, Simona Primasova, Jana Soukupova, Lubos Smutka
Introduction This paper investigates the links between deforestation and key economic, social, environmental, and geographical variables. We focus on per capita GDP, total forest cover, and the population across a diverse sample of countries from five continents for the last three decades. Methods This study utilizes a regression model using panel data to show the impact of key economic, and social variables on deforestation. Also, set of dummy variables is introduced in the paper. To enable the investigation, we use a set of dummies to capture their influence. The random effect specifications are used in this investigation. The research focuses on a period ranging from 1990 to 2020. Results Results show how different socio-economic variables influence deforestation. For example, disruptive events like the COVID-19 pandemic and the financial crisis had a negative effect on forest area development across all models. GDP per capita has different impact depending on the size of a country. Former colonies seem to have more deforestation. Conclusions The global environmental challenges posed by human activities and their impact on the state of forest have become increasingly evident. It is necessary to undertake policy and governance reforms to establish a solid legal framework, strengthen enforcement mechanisms, and foster transparency and accountability. The promotion of sustainable agriculture and agroforestry practices can substantially alleviate pressure on forests. Furthermore, it is necessary to mitigate disruptive events like pandemics by establishing specific strategies and creating contingency plans.
{"title":"Understanding the socio-economic causes of deforestation: a global perspective","authors":"Petr Prochazka, Josef Abrham, Jaroslav Cerveny, Lukas Kobera, Petra Sanova, Daniel Benes, Julia-Maria Fink, Eliska Jiraskova, Simona Primasova, Jana Soukupova, Lubos Smutka","doi":"10.3389/ffgc.2023.1288365","DOIUrl":"https://doi.org/10.3389/ffgc.2023.1288365","url":null,"abstract":"Introduction This paper investigates the links between deforestation and key economic, social, environmental, and geographical variables. We focus on per capita GDP, total forest cover, and the population across a diverse sample of countries from five continents for the last three decades. Methods This study utilizes a regression model using panel data to show the impact of key economic, and social variables on deforestation. Also, set of dummy variables is introduced in the paper. To enable the investigation, we use a set of dummies to capture their influence. The random effect specifications are used in this investigation. The research focuses on a period ranging from 1990 to 2020. Results Results show how different socio-economic variables influence deforestation. For example, disruptive events like the COVID-19 pandemic and the financial crisis had a negative effect on forest area development across all models. GDP per capita has different impact depending on the size of a country. Former colonies seem to have more deforestation. Conclusions The global environmental challenges posed by human activities and their impact on the state of forest have become increasingly evident. It is necessary to undertake policy and governance reforms to establish a solid legal framework, strengthen enforcement mechanisms, and foster transparency and accountability. The promotion of sustainable agriculture and agroforestry practices can substantially alleviate pressure on forests. Furthermore, it is necessary to mitigate disruptive events like pandemics by establishing specific strategies and creating contingency plans.","PeriodicalId":12538,"journal":{"name":"Frontiers in Forests and Global Change","volume":"182 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135732325","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Radial growth of trees can result in opposite wood (OW) and compression wood (CW) due to the varying impact of stem mechanical stress, such as that caused by gravity or wind. Previous research has identified higher xylem production in CW compared to OW. Yet, it remains unclear whether the difference in the number of xylem cells between OW and CW results from differences in growth rate or the duration of xylem cells. In this study, we collected wood microcores on a weekly basis from March 2019 to January 2020 in Pinus massoniana Lamb. located on a steep slope. Our objective was to compare the dynamic of cambial activity and resulting cellular anatomical parameters between OW and CW in a humid subtropical environment. Our results showed that the xylem phenology of OW and CW was generally consistent with the xylem cell division process beginning in early March and ceasing in November. The last latewood cell completed its differentiation at the end of December. The response of wood formation dynamics to climate was consistent in both OW and CW. Moreover, both wood types exhibited a limited development of the enlargement phase due to the heat and drought during the summer. The rate of cell division was responsible for 90.7% of the variability in the number of xylem cells. The CW xylem obtained a larger number of cells by increasing the rate of cell division and displayed thinner earlywood cells with larger lumens than OW cells. Our findings showed that the xylem of conifer species responds to mechanical stress by accelerating the cell division rate. As a result, we suggest calculating the ratio between OW and CW widths to reconstruct wind stress changes rather than calculating the residuals used in the current study.
{"title":"Intra-annual dynamic of opposite and compression wood formation of Pinus massoniana Lamb. in humid subtropical China","authors":"Chunsong Wang, Zhuangpeng Zheng, Feifei Zhou, Xinsheng Liu, Patrick Fonti, Jiani Gao, Keyan Fang","doi":"10.3389/ffgc.2023.1224838","DOIUrl":"https://doi.org/10.3389/ffgc.2023.1224838","url":null,"abstract":"Radial growth of trees can result in opposite wood (OW) and compression wood (CW) due to the varying impact of stem mechanical stress, such as that caused by gravity or wind. Previous research has identified higher xylem production in CW compared to OW. Yet, it remains unclear whether the difference in the number of xylem cells between OW and CW results from differences in growth rate or the duration of xylem cells. In this study, we collected wood microcores on a weekly basis from March 2019 to January 2020 in Pinus massoniana Lamb. located on a steep slope. Our objective was to compare the dynamic of cambial activity and resulting cellular anatomical parameters between OW and CW in a humid subtropical environment. Our results showed that the xylem phenology of OW and CW was generally consistent with the xylem cell division process beginning in early March and ceasing in November. The last latewood cell completed its differentiation at the end of December. The response of wood formation dynamics to climate was consistent in both OW and CW. Moreover, both wood types exhibited a limited development of the enlargement phase due to the heat and drought during the summer. The rate of cell division was responsible for 90.7% of the variability in the number of xylem cells. The CW xylem obtained a larger number of cells by increasing the rate of cell division and displayed thinner earlywood cells with larger lumens than OW cells. Our findings showed that the xylem of conifer species responds to mechanical stress by accelerating the cell division rate. As a result, we suggest calculating the ratio between OW and CW widths to reconstruct wind stress changes rather than calculating the residuals used in the current study.","PeriodicalId":12538,"journal":{"name":"Frontiers in Forests and Global Change","volume":"72 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135884700","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2023-10-17DOI: 10.3389/ffgc.2023.1233052
Allan Buras, Romy Rehschuh, Marina Fonti, Jelena Lange, Patrick Fonti, Annette Menzel, Arthur Gessler, Andreas Rigling, Kerstin Treydte, Georg von Arx
Climate change poses a major threat to global forest ecosystems. In particular, rising temperatures and prolonged drought spells have led to increased rates of forest decline and dieback in recent decades. Under this framework, forest edges are particularly prone to drought-induced decline since they are characterized by warmer and drier micro-climatic conditions amplifying impacts of drought on tree growth and survival. Previous research indicated that forest-edge Scots pine trees have a higher growth sensitivity to water availability compared to the forest interior with consequent reduction of canopy greenness (remotely sensed NDVI) and higher mortality rates. Yet, the underlying physiological mechanisms remain largely unknown. Here, we address this knowledge gap by comparing stable carbon isotope signatures and wood anatomical traits in annual rings of trees growing at the forest edge vs. the forest interior and between trees that either survived or died during the extreme drought of 2015. Our analyses suggest that the exposure to drought of forest-edge Scots pine likely results in a reduction of stomatal conductance, as reflected by a higher δ 13 C of stem wood, thinner cell walls, and lower mean ring density. Moreover, we found dead trees to feature larger mean hydraulic lumen diameters and a lower cell-wall reinforcement, indicating a higher risk to suffer from cavitation. In conclusion, the typically drier micro-climatic conditions at the forest edge seem to have triggered a larger reduction of stomatal conductance of Scots pine trees, resulting in a lower carbon availability and significantly altered wood anatomical properties under an increasingly drier climate.
{"title":"Quantitative wood anatomy and stable carbon isotopes indicate pronounced drought exposure of Scots pine when growing at the forest edge","authors":"Allan Buras, Romy Rehschuh, Marina Fonti, Jelena Lange, Patrick Fonti, Annette Menzel, Arthur Gessler, Andreas Rigling, Kerstin Treydte, Georg von Arx","doi":"10.3389/ffgc.2023.1233052","DOIUrl":"https://doi.org/10.3389/ffgc.2023.1233052","url":null,"abstract":"Climate change poses a major threat to global forest ecosystems. In particular, rising temperatures and prolonged drought spells have led to increased rates of forest decline and dieback in recent decades. Under this framework, forest edges are particularly prone to drought-induced decline since they are characterized by warmer and drier micro-climatic conditions amplifying impacts of drought on tree growth and survival. Previous research indicated that forest-edge Scots pine trees have a higher growth sensitivity to water availability compared to the forest interior with consequent reduction of canopy greenness (remotely sensed NDVI) and higher mortality rates. Yet, the underlying physiological mechanisms remain largely unknown. Here, we address this knowledge gap by comparing stable carbon isotope signatures and wood anatomical traits in annual rings of trees growing at the forest edge vs. the forest interior and between trees that either survived or died during the extreme drought of 2015. Our analyses suggest that the exposure to drought of forest-edge Scots pine likely results in a reduction of stomatal conductance, as reflected by a higher δ 13 C of stem wood, thinner cell walls, and lower mean ring density. Moreover, we found dead trees to feature larger mean hydraulic lumen diameters and a lower cell-wall reinforcement, indicating a higher risk to suffer from cavitation. In conclusion, the typically drier micro-climatic conditions at the forest edge seem to have triggered a larger reduction of stomatal conductance of Scots pine trees, resulting in a lower carbon availability and significantly altered wood anatomical properties under an increasingly drier climate.","PeriodicalId":12538,"journal":{"name":"Frontiers in Forests and Global Change","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135993601","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2023-10-17DOI: 10.3389/ffgc.2023.1278409
Carolina Mayoral, Susanna Ioni, Estrella Luna, Liam M. Crowley, Scott A. L. Hayward, Jon P. Sadler, A. Robert MacKenzie
Introduction Insect herbivores and biotrophic pathogens are major stressors influencing natural regeneration in woodlands. Information on the effect of elevated CO 2 (eCO 2 ) on plant-insect-pathogen interactions under natural conditions is lacking. Methods We studied the effects of eCO 2 on leaf-out phenology, as well as on levels of insect herbivory and powdery mildew (PM), i.e., reduction of leaf photosynthetic material. We then assessed the combined impacts of these biotic stressors and eCO 2 on seedling photosynthesis and growth. A total of 92 naturally recruited and 114 potted seedlings of 5 temperate tree species ( Quercus robur, Acer pseudoplatanus, Corylus avellana, Crataegus monogyna , and Ilex aquifolium ) within a mature oak woodland were studied. Results We found that eCO 2 advanced leaf-out phenology and was a significant explanatory variable for growth and physiological performance in potted seedlings. Potted oak seedlings experienced 11-fold higher tissue loss from insect herbivory than natural seedlings. The earliest leaf-flushing species, hawthorn, and the evergreen holly were resistant to insect attack and were not affected by PM. Oak was defoliated most but showed the highest regeneration capacity. Hazel was more resistant to PM infection than oak and sycamore. Despite being highly infected by PM, sycamore was less affected than oak. The more vigorous sycamore and oak seedlings suffered more severe PM disease. Conclusion No evidence emerged that eCO 2 enhances natural regeneration under biotic stress for any of the species studied.
{"title":"Elevated CO2 does not improve seedling performance in a naturally regenerated oak woodland exposed to biotic stressors","authors":"Carolina Mayoral, Susanna Ioni, Estrella Luna, Liam M. Crowley, Scott A. L. Hayward, Jon P. Sadler, A. Robert MacKenzie","doi":"10.3389/ffgc.2023.1278409","DOIUrl":"https://doi.org/10.3389/ffgc.2023.1278409","url":null,"abstract":"Introduction Insect herbivores and biotrophic pathogens are major stressors influencing natural regeneration in woodlands. Information on the effect of elevated CO 2 (eCO 2 ) on plant-insect-pathogen interactions under natural conditions is lacking. Methods We studied the effects of eCO 2 on leaf-out phenology, as well as on levels of insect herbivory and powdery mildew (PM), i.e., reduction of leaf photosynthetic material. We then assessed the combined impacts of these biotic stressors and eCO 2 on seedling photosynthesis and growth. A total of 92 naturally recruited and 114 potted seedlings of 5 temperate tree species ( Quercus robur, Acer pseudoplatanus, Corylus avellana, Crataegus monogyna , and Ilex aquifolium ) within a mature oak woodland were studied. Results We found that eCO 2 advanced leaf-out phenology and was a significant explanatory variable for growth and physiological performance in potted seedlings. Potted oak seedlings experienced 11-fold higher tissue loss from insect herbivory than natural seedlings. The earliest leaf-flushing species, hawthorn, and the evergreen holly were resistant to insect attack and were not affected by PM. Oak was defoliated most but showed the highest regeneration capacity. Hazel was more resistant to PM infection than oak and sycamore. Despite being highly infected by PM, sycamore was less affected than oak. The more vigorous sycamore and oak seedlings suffered more severe PM disease. Conclusion No evidence emerged that eCO 2 enhances natural regeneration under biotic stress for any of the species studied.","PeriodicalId":12538,"journal":{"name":"Frontiers in Forests and Global Change","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135992932","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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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