Mangrove forests are vulnerably threatened by sea level rise(SLR).Vegetation organic carbon(OC)stocks are important for mangrove ecosystem carbon cycle.It is critical to understand how SLR affects vegetation OC stocks...Mangrove forests are vulnerably threatened by sea level rise(SLR).Vegetation organic carbon(OC)stocks are important for mangrove ecosystem carbon cycle.It is critical to understand how SLR affects vegetation OC stocks for evaluating mangrove blue carbon budget and global climate change.In this study,biomass accumulation and OC stocks of mangrove vegetation were compared among three 10 year-old Kandelia obovata(a common species in China)mangrove forests under three intertidal elevations through species-specific allometric equations.This study simulated mangrove forests with SLR values of 0 cm,40 cm and 80 cm,respectively,representing for the current,future~100 a and future~200 a SLR of mangrove forests along the Jiulong River Estuary,China.SLR directly decreased mangrove individual density and inhibited the growth of mangrove vegetation.The total vegetation biomasses were(12.86±0.95)kg/m^2,(7.97±0.90)kg/m^2 and(3.89±0.63)kg/m^2 at Sites SLR 0 cm,SLR40 cm and SLR 80 cm,respectively.The total vegetation OC stock decreased by approximately 3.85 kg/m^2(in terms of C)from Site SLR 0 cm to Site SLR 80 cm.Significantly lower vegetation biomass and OC stock of various components(stem,branch,leaf and root)were found at Site SLR 80 cm.Annual increments of vegetation biomass and OC stock also decreased with SLR increase.Moreover,significant lower sedimentation rate was found at Site SLR 80 cm.These indicated that SLR will decrease mangrove vegetation biomass and OC stock,which may reduce global blue carbon sink by mangroves,exacerbate global warming and give positive feedback to SLR.展开更多
As the most northerly mangrove species in China, Kandelia obovata may undergo extreme cold event stress. Enhancing the cold tolerance of this species is crucial to its successful afforestation. This study aimed to det...As the most northerly mangrove species in China, Kandelia obovata may undergo extreme cold event stress. Enhancing the cold tolerance of this species is crucial to its successful afforestation. This study aimed to determine the resistance of K. obovata seedlings to low temperature stress by cold acclimation and to explain the mechanisms for alleviating cold injury. To understand these mechanisms, seedlings that were acclimatized and not acclimatized were exposed to 5℃/- 2℃(day/night)for 48 h.Results showed that low temperature stress reduced leaf photosynthesis of non-acclimatized seedlings by inducing oxidative stress and structural damage to chloroplasts. These phenomena were shown by increasing levels of malondialdehyde (MDA), O2-and H2O2, as well as decreasing enzyme activities in the ascorbate–glutathione (AsA-GSH) cycle. However, cold-acclimatized seedlings had improved photosynthetic rates and efficiency of photosystem II (PSII) under low temperature stress. Compared with non-acclimatized seedlings, leaves of coldacclimatized seedlings under low temperature stress for 48 h exhibited higher anti-oxidative enzyme activities, lower levels of O2^- and H2O2, less damage to chloroplast structure, and removed 33.7% of MDA at low temperature stress for 48 h. The data indicate that cold acclimation enhances photosynthetic capacity by effectively regulating activation in the PSII electron transport and the AsA–GSH cycle to scavenge excess ROS in chloroplasts, while the latter is more important.展开更多
Introduction:Mangroves that grow at the latitudinal extremes of their distribution are susceptible to extreme cold events.Successive enhancement of low temperature stress(seLTS)is a typical characteristic of extreme c...Introduction:Mangroves that grow at the latitudinal extremes of their distribution are susceptible to extreme cold events.Successive enhancement of low temperature stress(seLTS)is a typical characteristic of extreme cold events.Low temperature stress can inhibit mangrove photosynthesis,which often inhibits the growth and development of mangroves.However,the possible reasons for impairment to photosynthesis of mangroves due to extreme cold events remain unclear.Methods:Kandelia obovata seedlings in a growth chamber were exposed to 5℃/−2℃(day/night)for 36 h(−2℃ for 16 h)with 12 h light per day at 600μmol m^(−2) s^(−1) photosynthetic photon flux density(PPFD)(a low temperature stress,aLTS),then the plants were transferred to the control condition(15℃/10℃(day/night)and allowed to recover for 5 days(R1).The other seedlings were subjected to low temperature treatment with a day/night temperature of 5℃/−1℃ in a growth chamber for 24 h.Then these plants were transferred to 5℃/−2℃(day/night)under the same light and climate conditions for 36 h(two low temperature stresses,tLTS).Following the successive enhancement of low temperature treatment,these plants were returned to 15℃/10℃(day/night)for another 5-day recovery period(R2).Results:Results showed that aLTS treatment significantly reduced leaf net photosynthetic rate(P_(n))and stomatal conductance(G_(s)),while increased intercellular CO_(2) concentration(C_(i)).Photosynthetic activity of leaves quickly recovered after the plants were returned to control temperature for 5 days(R1).However,decreases in leaf Pn were more obvious under tLTS treatment than those under aLTS treatment.This reduced Pn might be attributed to stomatal and non-stomatal limitations.Moreover,non-stomatal limitation played a major role in reducing Pn during tLTS treatment,as proven by reduced ribulose 1,5-biphosphate carboxylase(RuBPCase)activity.This limitation also enhanced lipid peroxidation in chloroplasts,decreased sucrosemetabolizing enzymes and ratios of both chlorophyll a/chlorophyll b(Chl a/b)and chlorophyll/carotenoids(Chl/Car),and increased protease senescence.Damages of tLTS treatment to photosynthesis were insufficiently alleviated even after the plants were returned to control temperature for 5 days(R2).Conclusions:Successive enhancement of low temperature depressed successful recovery of leaf photosynthesis of K.obovata seedlings mainly by impairing pigment synthesis,antioxidant metabolism,and sucrose translocation,as well as accelerating senescence of endopeptidase.Furthermore,our results suggest that decreases in sucrose content in leaves might also account for increases in reactive oxygen species(ROS)in chloroplasts.展开更多
Introduction:Understanding how mangroves respond to rare cold events has implications for both restoration and conservation under climate change scenarios.This study investigated the responses of photosynthesis and ac...Introduction:Understanding how mangroves respond to rare cold events has implications for both restoration and conservation under climate change scenarios.This study investigated the responses of photosynthesis and activities of key enzymes involving carbon and nitrogen metabolism at different ages of Kandelia obovata to a rare cold event in the winter of 2010.Methods:This study took place on Ximen Island,Zhejiang Province,China.We measured the physiological recovery of 2-3-,5-6-,9-10-and 54-55-year-old K.obovata trees after freezing injury in February and March in 2011 and 2012,respectively.Results:Chilling injury index and electrolyte leakage of K.obovata increased with increasing tree age in the winter of 2010,and electrolyte leakage in K.obovata at different ages in the winter of 2010 was far higher than that in the winter of 2011.The rare cold events significantly changed the recoveries of the leaf net photosynthetic rate(Pn)and stomatal conductance(Gs);ratios of chlorophyll a/chlorophyll b(Chl a/Chl b);contents of total soluble sugar(TSS),sucrose,free amino acid(FAA),and soluble protein;and activities of sucrose phosphate synthase(SPS),endopeptidase,and carboxypeptidase in K.obovata at different ages.These effects were mainly due to changes in the physiological mechanism in the 2-year-old trees.A clear decrease in Pn of the 2-year-old trees was observed in February 2011,as exemplified by reductions in ratios of Chl a/Chl b and chlorophyll/carotenoid(Chl/Car),as well as inhibition of the levels of TSS and FAA(osmotic substances).During recovery in 2011 and 2012,the activities of SPS and sucrose synthase(SS)were responsible for sucrose synthesis after the rare cold events in 2011,but only SPS activity was one of the main factors contributing to the metabolism of stachyose to sucrose without cold damage in 2012.Carboxypeptidase played a more important role than endopeptidase during protein hydrolysis after the rare cold events.Conclusions:The results suggest that the recovery of photosynthetic capacity in K.obovata was changed after a rare cold event,which is associated with pigment components and activities of SS,SPS,and carboxypeptidase,especially the seedlings.展开更多
基金The National Natural Science Foundation of China under contract Nos 41776097 and 42076142the Scientific Research Foundation of Third Institute of Oceanography,Ministry of Natural Resources under contract No.2019017the Fujian Provincial Key Laboratory of Marine Ecological Conservation and Restoration under contract No.EPR2020003。
文摘Mangrove forests are vulnerably threatened by sea level rise(SLR).Vegetation organic carbon(OC)stocks are important for mangrove ecosystem carbon cycle.It is critical to understand how SLR affects vegetation OC stocks for evaluating mangrove blue carbon budget and global climate change.In this study,biomass accumulation and OC stocks of mangrove vegetation were compared among three 10 year-old Kandelia obovata(a common species in China)mangrove forests under three intertidal elevations through species-specific allometric equations.This study simulated mangrove forests with SLR values of 0 cm,40 cm and 80 cm,respectively,representing for the current,future~100 a and future~200 a SLR of mangrove forests along the Jiulong River Estuary,China.SLR directly decreased mangrove individual density and inhibited the growth of mangrove vegetation.The total vegetation biomasses were(12.86±0.95)kg/m^2,(7.97±0.90)kg/m^2 and(3.89±0.63)kg/m^2 at Sites SLR 0 cm,SLR40 cm and SLR 80 cm,respectively.The total vegetation OC stock decreased by approximately 3.85 kg/m^2(in terms of C)from Site SLR 0 cm to Site SLR 80 cm.Significantly lower vegetation biomass and OC stock of various components(stem,branch,leaf and root)were found at Site SLR 80 cm.Annual increments of vegetation biomass and OC stock also decreased with SLR increase.Moreover,significant lower sedimentation rate was found at Site SLR 80 cm.These indicated that SLR will decrease mangrove vegetation biomass and OC stock,which may reduce global blue carbon sink by mangroves,exacerbate global warming and give positive feedback to SLR.
基金supported by Zhejiang Provincial Natural Science Foundation of China(Grant Nos.LY18C030001 and LQ13C030002)National Natural Science Foundation of China(Grant No.41776097)+4 种基金Special Funding for Research of National Oceanic Public Service Industry of China(Grant No.201505028)National Science and Technology Basic Resources Survey Special of China(Grant No.2017FY100700)Zhejiang Province Science and Technology Plan Project of China(Grant Nos.2013C25096 and2014F50003)Zhejiang Province Foundation of the Nonprofit Technology Research Projects of China(Grant No.2015C33227)Wenzhou Municipal Science and Technology Plan Project of China(Grant Nos.N20140046,N20170008 and S20160004)
文摘As the most northerly mangrove species in China, Kandelia obovata may undergo extreme cold event stress. Enhancing the cold tolerance of this species is crucial to its successful afforestation. This study aimed to determine the resistance of K. obovata seedlings to low temperature stress by cold acclimation and to explain the mechanisms for alleviating cold injury. To understand these mechanisms, seedlings that were acclimatized and not acclimatized were exposed to 5℃/- 2℃(day/night)for 48 h.Results showed that low temperature stress reduced leaf photosynthesis of non-acclimatized seedlings by inducing oxidative stress and structural damage to chloroplasts. These phenomena were shown by increasing levels of malondialdehyde (MDA), O2-and H2O2, as well as decreasing enzyme activities in the ascorbate–glutathione (AsA-GSH) cycle. However, cold-acclimatized seedlings had improved photosynthetic rates and efficiency of photosystem II (PSII) under low temperature stress. Compared with non-acclimatized seedlings, leaves of coldacclimatized seedlings under low temperature stress for 48 h exhibited higher anti-oxidative enzyme activities, lower levels of O2^- and H2O2, less damage to chloroplast structure, and removed 33.7% of MDA at low temperature stress for 48 h. The data indicate that cold acclimation enhances photosynthetic capacity by effectively regulating activation in the PSII electron transport and the AsA–GSH cycle to scavenge excess ROS in chloroplasts, while the latter is more important.
基金funded by the projects of Special Funding for Research of National Oceanic Public Service Industry(201505028)Zhejiang Provincial Natural Science Foundation(LQ13C030002)+2 种基金Science and Technology Plan of Zhejiang Province(2012C12017-3,2013C25096,and 2014F50003)China and Israel Cooperation Project(2015)Wenzhou Municipal Science and Technology Plan Project(S20110007).
文摘Introduction:Mangroves that grow at the latitudinal extremes of their distribution are susceptible to extreme cold events.Successive enhancement of low temperature stress(seLTS)is a typical characteristic of extreme cold events.Low temperature stress can inhibit mangrove photosynthesis,which often inhibits the growth and development of mangroves.However,the possible reasons for impairment to photosynthesis of mangroves due to extreme cold events remain unclear.Methods:Kandelia obovata seedlings in a growth chamber were exposed to 5℃/−2℃(day/night)for 36 h(−2℃ for 16 h)with 12 h light per day at 600μmol m^(−2) s^(−1) photosynthetic photon flux density(PPFD)(a low temperature stress,aLTS),then the plants were transferred to the control condition(15℃/10℃(day/night)and allowed to recover for 5 days(R1).The other seedlings were subjected to low temperature treatment with a day/night temperature of 5℃/−1℃ in a growth chamber for 24 h.Then these plants were transferred to 5℃/−2℃(day/night)under the same light and climate conditions for 36 h(two low temperature stresses,tLTS).Following the successive enhancement of low temperature treatment,these plants were returned to 15℃/10℃(day/night)for another 5-day recovery period(R2).Results:Results showed that aLTS treatment significantly reduced leaf net photosynthetic rate(P_(n))and stomatal conductance(G_(s)),while increased intercellular CO_(2) concentration(C_(i)).Photosynthetic activity of leaves quickly recovered after the plants were returned to control temperature for 5 days(R1).However,decreases in leaf Pn were more obvious under tLTS treatment than those under aLTS treatment.This reduced Pn might be attributed to stomatal and non-stomatal limitations.Moreover,non-stomatal limitation played a major role in reducing Pn during tLTS treatment,as proven by reduced ribulose 1,5-biphosphate carboxylase(RuBPCase)activity.This limitation also enhanced lipid peroxidation in chloroplasts,decreased sucrosemetabolizing enzymes and ratios of both chlorophyll a/chlorophyll b(Chl a/b)and chlorophyll/carotenoids(Chl/Car),and increased protease senescence.Damages of tLTS treatment to photosynthesis were insufficiently alleviated even after the plants were returned to control temperature for 5 days(R2).Conclusions:Successive enhancement of low temperature depressed successful recovery of leaf photosynthesis of K.obovata seedlings mainly by impairing pigment synthesis,antioxidant metabolism,and sucrose translocation,as well as accelerating senescence of endopeptidase.Furthermore,our results suggest that decreases in sucrose content in leaves might also account for increases in reactive oxygen species(ROS)in chloroplasts.
基金funded by projects of special Funding for Research of National Oceanic Public Service Industry(201505028)Zhejiang Provincial Natural Science Foundation(LQ13C030002)+1 种基金Science and Technology Plan Zhejiang Province(2012C12017-3,2013C25096,2014F50003)Zhejiang Province pelagic fishery(2015)“Cooperation and exchange of aquaculture technology between China and Israel based on the level of ecological system,”and Wenzhou Municipal Science。
文摘Introduction:Understanding how mangroves respond to rare cold events has implications for both restoration and conservation under climate change scenarios.This study investigated the responses of photosynthesis and activities of key enzymes involving carbon and nitrogen metabolism at different ages of Kandelia obovata to a rare cold event in the winter of 2010.Methods:This study took place on Ximen Island,Zhejiang Province,China.We measured the physiological recovery of 2-3-,5-6-,9-10-and 54-55-year-old K.obovata trees after freezing injury in February and March in 2011 and 2012,respectively.Results:Chilling injury index and electrolyte leakage of K.obovata increased with increasing tree age in the winter of 2010,and electrolyte leakage in K.obovata at different ages in the winter of 2010 was far higher than that in the winter of 2011.The rare cold events significantly changed the recoveries of the leaf net photosynthetic rate(Pn)and stomatal conductance(Gs);ratios of chlorophyll a/chlorophyll b(Chl a/Chl b);contents of total soluble sugar(TSS),sucrose,free amino acid(FAA),and soluble protein;and activities of sucrose phosphate synthase(SPS),endopeptidase,and carboxypeptidase in K.obovata at different ages.These effects were mainly due to changes in the physiological mechanism in the 2-year-old trees.A clear decrease in Pn of the 2-year-old trees was observed in February 2011,as exemplified by reductions in ratios of Chl a/Chl b and chlorophyll/carotenoid(Chl/Car),as well as inhibition of the levels of TSS and FAA(osmotic substances).During recovery in 2011 and 2012,the activities of SPS and sucrose synthase(SS)were responsible for sucrose synthesis after the rare cold events in 2011,but only SPS activity was one of the main factors contributing to the metabolism of stachyose to sucrose without cold damage in 2012.Carboxypeptidase played a more important role than endopeptidase during protein hydrolysis after the rare cold events.Conclusions:The results suggest that the recovery of photosynthetic capacity in K.obovata was changed after a rare cold event,which is associated with pigment components and activities of SS,SPS,and carboxypeptidase,especially the seedlings.
