Climate change is expected to alter the popu-lation dynamics of pioneer tree species and their planned use in sustainable forest management,but we have a lim-ited understanding of how their demographic rates change in...Climate change is expected to alter the popu-lation dynamics of pioneer tree species and their planned use in sustainable forest management,but we have a lim-ited understanding of how their demographic rates change in response to climate changes during ecological restora-tion.Based on 12 years of demographic data for a pioneer tree species(Pinus massoniana)censused in three plots that correspond to three stages of ecological restoration in south-eastern China.We built integral projection models(IPMs)to assess vital rates(survival,growth,reproduction)and population growth in each plot,then evaluated demographic changes to simulated changes in seasonal mean temperature and precipitation in the current and previous census period.The plot representing the medium restoration stage had the highest population growth rate(λ=0.983).Mean population survival probability increased with ecological restoration,and reproduction probability was significantly suppressed at the high restoration stage.Survival is always the most important vital rate forλ,and climate affectsλprimarily via survival at each restoration stage.The current spring tem-perature was the most critical climate variable forλin the low and medium restoration stages,and previous summer temperature was most critical in the high restoration stage.Simulated warming leads to a decrease in the stochastic population growth rate(λ_(s))of P.massoniana in every stage.These findings suggest that during ecological restoration,P.massoniana responds to habitat change via modified demo-graphic performance,thus altering its response to climate change.Despite diverse responses to climate change,the persistence of P.massoniana populations is facing a wide-spread threat of warming states at each restoration stages.展开更多
Sea asparagus is a newly emerging seawater-irrigated vegetable. Firstly, the economic value of sea asparagus was introduced, and then, someexploiting approaches of sea asparagus werefully reviewed. The exploiting appr...Sea asparagus is a newly emerging seawater-irrigated vegetable. Firstly, the economic value of sea asparagus was introduced, and then, someexploiting approaches of sea asparagus werefully reviewed. The exploiting approaches mainly include fresh vegetable, pickle, bio-salt, health-care products, animal feed, vegetable oil, bio-diesel and skin-care products.展开更多
A protocol of polymerase chain reaction-random amplified polymorphic DNAs (PCR-RAPDs) was established to analyse the gene diversity and genotype identification for clones of Sequoia sempervirens (D. Don) Endl. in Chil...A protocol of polymerase chain reaction-random amplified polymorphic DNAs (PCR-RAPDs) was established to analyse the gene diversity and genotype identification for clones of Sequoia sempervirens (D. Don) Endl. in Chile. Ten (out of 34) clones from introduction trial located in Voipir-Villarrica, Chile, were studied. The PCR-RAPDs technique and a modified hexadecyltrimethylammonium bromide (CTAB) protocol were used for genomic DNA extraction. The PCR tests were carried out employing 10-mer random primers. The amplification products were detected by electrophoresis in agarose gels. Forty nine polymorphic bands were obtained with the selected primers (BG04, BF07, BF12, BF13, and BF14) and were ordered according to their molecular size. The genetic similarity between samples was calculated by the Jaccard index and a dendrogram was con- structed using a cluster analysis of unweighted pair group method using arithmetic averages (UPGMA). Of the primers tested, 5 (out of 60) RAPD primers were selected for their reproducibility and high polymorphism. A total of 49 polymorphic RAPD bands were detected out of 252 bands. The genetic similarity analysis demonstrates an extensive genetic variability between the tested clones and the dendrogram depicts the genetic relationships among the clones, suggesting a geographic relationship. The results indicate that the RAPD markers permitted the identification of the assayed clones, although they are derived from the same geo- graphic origin.展开更多
Several species of the fungal genus Trichoderma establish biological interactions with various micro- and macro-organisms. Some of these interactions are relevant in ecological terms and in biotechnological applicatio...Several species of the fungal genus Trichoderma establish biological interactions with various micro- and macro-organisms. Some of these interactions are relevant in ecological terms and in biotechnological applications, such as biocontrol, where Trichoderma could be considered as an invasive species that colonizes a recipient community. The success of this invasion depends on multiple factors, which can be assayed using experimental communities as study models. Therefore, the aim of this work is to develop a species-specific sequence-characterized amplified region （SCAR） marker to monitor the colonization and growth of T. cf. harzianum when it invades experi- mental communities. For this study, 16 randomly amplified polymorphic DNA （RAPD） primers of 10-mer were used to generate polymorphic patterns, one of which generated a band present only in strains of T. cf. harzianum. This band was cloned, sequenced, and five primers of 20-23 mer were designed. Primer pairs 2F2/2R2 and 2F2/2R3 successfully and specifically amplified fragments of 278 and 448 bp from the T. cf. harzianum BpT10a strain DNA, respectively. Both primer pairs were also tested against the DNA from 14 strains of T. cf. harzianum and several strains of different fungal genera as specificity controls. Only the DNA from the strains of T. cf. hat-zianum was successfully amplified. Moreover, primer pair 2F2/2R2 was assessed by quantitative real-time polymerase chain reaction （PCR） using fungal DNA mixtures and DNA extracted from fungal experimental communities as templates. T. cf. harzianum was detectable even when as few as 100 copies of the SCAR marker were available or even when its population represented only 0.1% of the whole community.展开更多
Soil microbial mutualists of plants, including mycorrhizal ftmgi, non- mycorrhizal fungi and plant growth promoting rhizobacteria, have been typically characterized for increasing nutrient acquisition and plant growth...Soil microbial mutualists of plants, including mycorrhizal ftmgi, non- mycorrhizal fungi and plant growth promoting rhizobacteria, have been typically characterized for increasing nutrient acquisition and plant growth. More recently, soil microbes have also been shown to increase direct plant defense against above- and below- ground herbivores. Plants, however, do not only rely on direct defenses when attacked, but they can also recruit pest antagonists such as predators and parasitoids, both above and belowground, mainly via the release of volatile organic compounds （i.e., indirect defenses）. In this review, we illustrate the main features and effects of soil microbial mutualists of plants on plant indirect defenses and discuss possible applications within the framework of sustainable crop protection against root- and shoot-feeding arthropod pests. We indicate the main knowledge gaps and the future challenges to be addressed in the study and application of these rnultifaceted interactions.展开更多
Aims Grasslands are globally threatened by climate changes and unsustainable land-use,which often cause transitions among alternative stable states,and even catastrophic transition to desertification.Spatial vegetatio...Aims Grasslands are globally threatened by climate changes and unsustainable land-use,which often cause transitions among alternative stable states,and even catastrophic transition to desertification.Spatial vegetation patch configurations have been shown to signify such transitions at large spatial scale.Here,we demonstrate how small-scale patch configurations can also indicate state transitions.Methods The whole spatial series of degradation successions were chosen in alpine grasslands characterized as seven typical communities.Patch numbers,and perimeter and cover of each patch were recorded using adjacent quadrats along transects in each type of the communities.Species abundance within each patch was measured.Important Findings Across seven grazing-induced degradation stages in the world’s largest expanse of grassland,from dense ungrazed turf to bare black-soil crust,patch numbers and perimeters first increased as patch cover decreased.Numbers and perimeters then decreased rapidly beyond an intersection point at 68%of initial continuous vegetation cover.Around this point,the vegetation fluctuated back and forth between the sedge-dominated grassland breaking-up phase and the forb-dominated phase,suggesting impending shift of grassland state.This study thus demonstrates how ground-based small-scale vegetation surveys can provide a quantitative,easy-to-use signals for vegetation degradation,with promise for detecting the catastrophic transition to desertification.展开更多
Aims Multi-stemming supports plants’resilience to disturbances and then contributes to soil stabilization and forest function,especially in mountain habitats.Many questions remain about(i)the ontogenetic phase at whi...Aims Multi-stemming supports plants’resilience to disturbances and then contributes to soil stabilization and forest function,especially in mountain habitats.Many questions remain about(i)the ontogenetic phase at which multiple stems can occur,(ii)how habitat drivers affect multi-stemming and(iii)whether ontogenetic phase and habitat drivers interact.We asked these questions for Quercus glauca(ring-cupped oak),the dominant species and sprouter across large warm-temperate areas of Asia;its multi-stemmed trees reflect individual survival,population regeneration and forest ecosystem stability.Methods In a 5-ha permanent plot of subtropical evergreen broad-leaved forest in eastern China,we examined the temporal patterns and spatial distribution of multi-stemmed trees of Q.glauca within 99 quadrats of 20 m×20 m.Important Findings There were three temporal modes for multi-stemming among the Q.glauca trees and most of them appeared to produce multiple stems from an early stage.Environmental disturbances related to slope convexity appear to be the main drivers of multi-stemming of Q.glauca.Moreover,the closer to the ridge,the earlier the multi-stemming occurs.Thus,also for other woody species in other forests and climate zones,ontogeny and environmental drivers promoting disturbance(not only geomorphology,but also extreme weather events,soil drought,fire),as well as soil fertility,need to be considered in combination to better understand multi-stemming and its consequences for community structure.展开更多
There are gaps in our understanding of plant responses under different insect phytophagy modes and their subsequent effects on the insect herbivores＇ performance at late season. Here we compared different types of in...There are gaps in our understanding of plant responses under different insect phytophagy modes and their subsequent effects on the insect herbivores＇ performance at late season. Here we compared different types of insect feeding by an aphid, Lipaphis erysimi, and a lepidopteran, Plutella xylostella, and how this affected defensive metabolites in leaves of 2 Brassica species when plants gain maturity. Thiocyanate concentrations after P xylostella and L. erysimi feeding activities were the same. Total phenolics was higher after the phloem feeder feeding than the folivore activity. The plants compensatory responses （i.e., tolerance） to L. erysimi feeding was significantly higher than the responses to P xylostella. This study showed that L. erysirni had higher carbon than P xylostella whereas nitrogen in P xylostella was 1.42 times that in L. erysimi. Population size of the phloem feeder was not affected by plant species or insect coexistence. However, there was no correlation between plant defensive metabolites and both insects＇ population size and biomass. This suggests that plant root biomass and tolerance index after different insect herbivory modes are not necessarily unidirectional. Importantly, the interaction between the folivore and the phloem feeder insects is asymmetric and the phloem feeder might be a trickier problem for plants than the folivore. Moreover, as both plants＇ common and special defenses decreased under interspecific interference, we suggest that specialist insect herbivores can be more challenged in ecosystems in which plants are not involved in interspecific interference.展开更多
Patterns of plant trait variation across spatial scales are important for understanding ecosystem functioning and services.However,habitat-related drivers of these patterns are poorly understood.In a conceptual model,...Patterns of plant trait variation across spatial scales are important for understanding ecosystem functioning and services.However,habitat-related drivers of these patterns are poorly understood.In a conceptual model,we ask whether and how the patterns of within-and among-site plant trait variation are driven by habitat type(terrestrial vs.wetland)across large climatic gradients.We tested these through spatial-hierarchical-sampling of leaves in herbaceous-dominated terrestrial and wetland communities within each of 26 sites across China.For all 13 plant traits,within-site variation was larger than among-site variation in both terrestrial and wetland habitats.Within-site variation was similar in most leaf traits related to carbon and nutrient economics but larger in specific leaf area and size-related traits(plant height,leaf area and thickness)in wetland compared to terrestrial habitats.Among-site variation was larger in terrestrial than wetland habitats for 10 leaf traits but smaller for plant height,leaf area and leaf nitrogen.Our results indicate the important role of local ecological processes in driving plant trait variation among coexisting species and the dependence of functional variation across habitats on traits considered.These findings will help to understand and predict the effects of climatic or land-use changes on ecosystem functioning and services.展开更多
Aims The redistribution of forest gaps based on solar radiation and precipitation(mainly rainfall and snowfall)can create heterogenous microenvironments inside and outside the gaps.Here,we investigated the effects of ...Aims The redistribution of forest gaps based on solar radiation and precipitation(mainly rainfall and snowfall)can create heterogenous microenvironments inside and outside the gaps.Here,we investigated the effects of forest gaps on carbon(C),nitrogen(N)and phosphorus(P)stoichiometry in decaying logs by altering the microenvironments.Methods Minjiang fir(Abies faxoniana)logs of decay classes I–V were incubated in situ on the floor under the gap center(GC),gap edge(GE)and closed canopy(CC)in a subalpine forest in the eastern Qinghai-Tibet Plateau.The C,N and P concentrations in decaying bark,sapwood and heartwood were measured in August from 2013 to 2016.Important Findings Our results showed that the N concentration in bark decreased from the CC to the GC,while the opposite trend was found in sapwood and heartwood.Additionally,the C/N ratio in sapwood and heartwood of decay classes IV and V decreased from the CC to the GC,and the N/P ratio in heartwood of decay class V increased from the CC to the GC,implying that forest gaps have strong effects on C/N/P stoichiometry in highly decayed logs.Briefly,highly decayed logs are more susceptible to the microenvironment,and the proportion of highly decayed logs under the CC or the GC should be appropriately adjusted if necessary.展开更多
During vertebrate development,the immune function is inefficient and is mainly controlled by innate defense.While there have been detailed studies of various aspects of innate immune function,the effects of this func&...During vertebrate development,the immune function is inefficient and is mainly controlled by innate defense.While there have been detailed studies of various aspects of innate immune function,the effects of this function in the growth of vertebrates is still not well known.Similarly,there is little information regarding how early endotoxin exposure would affect juvenile phenotypes,specifically in a non-model mammal like a precocial rodent.We evaluated the response to an antigen and its cost in offspring of the rodent Octodon degus.We inoculated pups at 4 different ages(8,15,22 and 30 days after birth)with an antigen to determine the ontogeny and costs of the response to an endotoxin.We assessed changes in body mass,body temperature,sickness behavior and the levels of a key mediator of the inflammatory response,the cytokine interleukin-1β.We also determined the effects of early endotoxin exposure on the resting metabolic rate of juvenile animals(i.e.90 days after birth).The cytokine levels,body mass and body temperature were unaffected by time of inoculation and treatment.However,pups subjected to inoculation at 22 days after birth with the antigen showed reduced locomotion.Juvenile resting metabolic rate was not affected by early endotoxin exposure.These results suggest that the magnitude of O.degus responses would not change with age.We discuss whether the lack of effect of the response on body mass or body condition is caused by environmental variables or by the precocial characteristics of O.degus.展开更多
基金supported by the National Natural Science Foundation of China(grant no.31971638)the Public Welfare Project of Fujian Science and Technology Department(grant no.2024R1002001).
文摘Climate change is expected to alter the popu-lation dynamics of pioneer tree species and their planned use in sustainable forest management,but we have a lim-ited understanding of how their demographic rates change in response to climate changes during ecological restora-tion.Based on 12 years of demographic data for a pioneer tree species(Pinus massoniana)censused in three plots that correspond to three stages of ecological restoration in south-eastern China.We built integral projection models(IPMs)to assess vital rates(survival,growth,reproduction)and population growth in each plot,then evaluated demographic changes to simulated changes in seasonal mean temperature and precipitation in the current and previous census period.The plot representing the medium restoration stage had the highest population growth rate(λ=0.983).Mean population survival probability increased with ecological restoration,and reproduction probability was significantly suppressed at the high restoration stage.Survival is always the most important vital rate forλ,and climate affectsλprimarily via survival at each restoration stage.The current spring tem-perature was the most critical climate variable forλin the low and medium restoration stages,and previous summer temperature was most critical in the high restoration stage.Simulated warming leads to a decrease in the stochastic population growth rate(λ_(s))of P.massoniana in every stage.These findings suggest that during ecological restoration,P.massoniana responds to habitat change via modified demo-graphic performance,thus altering its response to climate change.Despite diverse responses to climate change,the persistence of P.massoniana populations is facing a wide-spread threat of warming states at each restoration stages.
文摘Sea asparagus is a newly emerging seawater-irrigated vegetable. Firstly, the economic value of sea asparagus was introduced, and then, someexploiting approaches of sea asparagus werefully reviewed. The exploiting approaches mainly include fresh vegetable, pickle, bio-salt, health-care products, animal feed, vegetable oil, bio-diesel and skin-care products.
基金Project (No.CONICYT-FONDEF PROYECT D01 I 1008) supported by the National Commission of Science and Research of Chile
文摘A protocol of polymerase chain reaction-random amplified polymorphic DNAs (PCR-RAPDs) was established to analyse the gene diversity and genotype identification for clones of Sequoia sempervirens (D. Don) Endl. in Chile. Ten (out of 34) clones from introduction trial located in Voipir-Villarrica, Chile, were studied. The PCR-RAPDs technique and a modified hexadecyltrimethylammonium bromide (CTAB) protocol were used for genomic DNA extraction. The PCR tests were carried out employing 10-mer random primers. The amplification products were detected by electrophoresis in agarose gels. Forty nine polymorphic bands were obtained with the selected primers (BG04, BF07, BF12, BF13, and BF14) and were ordered according to their molecular size. The genetic similarity between samples was calculated by the Jaccard index and a dendrogram was con- structed using a cluster analysis of unweighted pair group method using arithmetic averages (UPGMA). Of the primers tested, 5 (out of 60) RAPD primers were selected for their reproducibility and high polymorphism. A total of 49 polymorphic RAPD bands were detected out of 252 bands. The genetic similarity analysis demonstrates an extensive genetic variability between the tested clones and the dendrogram depicts the genetic relationships among the clones, suggesting a geographic relationship. The results indicate that the RAPD markers permitted the identification of the assayed clones, although they are derived from the same geo- graphic origin.
基金Project supported by the Chilean National Fund for Scientific and Technological Development(FONDECYT)(No.1120508)
文摘Several species of the fungal genus Trichoderma establish biological interactions with various micro- and macro-organisms. Some of these interactions are relevant in ecological terms and in biotechnological applications, such as biocontrol, where Trichoderma could be considered as an invasive species that colonizes a recipient community. The success of this invasion depends on multiple factors, which can be assayed using experimental communities as study models. Therefore, the aim of this work is to develop a species-specific sequence-characterized amplified region （SCAR） marker to monitor the colonization and growth of T. cf. harzianum when it invades experi- mental communities. For this study, 16 randomly amplified polymorphic DNA （RAPD） primers of 10-mer were used to generate polymorphic patterns, one of which generated a band present only in strains of T. cf. harzianum. This band was cloned, sequenced, and five primers of 20-23 mer were designed. Primer pairs 2F2/2R2 and 2F2/2R3 successfully and specifically amplified fragments of 278 and 448 bp from the T. cf. harzianum BpT10a strain DNA, respectively. Both primer pairs were also tested against the DNA from 14 strains of T. cf. harzianum and several strains of different fungal genera as specificity controls. Only the DNA from the strains of T. cf. hat-zianum was successfully amplified. Moreover, primer pair 2F2/2R2 was assessed by quantitative real-time polymerase chain reaction （PCR） using fungal DNA mixtures and DNA extracted from fungal experimental communities as templates. T. cf. harzianum was detectable even when as few as 100 copies of the SCAR marker were available or even when its population represented only 0.1% of the whole community.
文摘Soil microbial mutualists of plants, including mycorrhizal ftmgi, non- mycorrhizal fungi and plant growth promoting rhizobacteria, have been typically characterized for increasing nutrient acquisition and plant growth. More recently, soil microbes have also been shown to increase direct plant defense against above- and below- ground herbivores. Plants, however, do not only rely on direct defenses when attacked, but they can also recruit pest antagonists such as predators and parasitoids, both above and belowground, mainly via the release of volatile organic compounds （i.e., indirect defenses）. In this review, we illustrate the main features and effects of soil microbial mutualists of plants on plant indirect defenses and discuss possible applications within the framework of sustainable crop protection against root- and shoot-feeding arthropod pests. We indicate the main knowledge gaps and the future challenges to be addressed in the study and application of these rnultifaceted interactions.
基金supported by the Second Tibetan Plateau Scientific Expedition and Research(STEP)(grant no.2019QZKK0302)the National Key Research and Development Program(2016YFC0501802,2016YFC0501803)the National Natural Science Foundation of China(41671263,41730752).
文摘Aims Grasslands are globally threatened by climate changes and unsustainable land-use,which often cause transitions among alternative stable states,and even catastrophic transition to desertification.Spatial vegetation patch configurations have been shown to signify such transitions at large spatial scale.Here,we demonstrate how small-scale patch configurations can also indicate state transitions.Methods The whole spatial series of degradation successions were chosen in alpine grasslands characterized as seven typical communities.Patch numbers,and perimeter and cover of each patch were recorded using adjacent quadrats along transects in each type of the communities.Species abundance within each patch was measured.Important Findings Across seven grazing-induced degradation stages in the world’s largest expanse of grassland,from dense ungrazed turf to bare black-soil crust,patch numbers and perimeters first increased as patch cover decreased.Numbers and perimeters then decreased rapidly beyond an intersection point at 68%of initial continuous vegetation cover.Around this point,the vegetation fluctuated back and forth between the sedge-dominated grassland breaking-up phase and the forb-dominated phase,suggesting impending shift of grassland state.This study thus demonstrates how ground-based small-scale vegetation surveys can provide a quantitative,easy-to-use signals for vegetation degradation,with promise for detecting the catastrophic transition to desertification.
基金supported by the Natural Science Foundation of Zhejiang Province(LY17C030001)the National Natural Science Foundation of China(31971426).
文摘Aims Multi-stemming supports plants’resilience to disturbances and then contributes to soil stabilization and forest function,especially in mountain habitats.Many questions remain about(i)the ontogenetic phase at which multiple stems can occur,(ii)how habitat drivers affect multi-stemming and(iii)whether ontogenetic phase and habitat drivers interact.We asked these questions for Quercus glauca(ring-cupped oak),the dominant species and sprouter across large warm-temperate areas of Asia;its multi-stemmed trees reflect individual survival,population regeneration and forest ecosystem stability.Methods In a 5-ha permanent plot of subtropical evergreen broad-leaved forest in eastern China,we examined the temporal patterns and spatial distribution of multi-stemmed trees of Q.glauca within 99 quadrats of 20 m×20 m.Important Findings There were three temporal modes for multi-stemming among the Q.glauca trees and most of them appeared to produce multiple stems from an early stage.Environmental disturbances related to slope convexity appear to be the main drivers of multi-stemming of Q.glauca.Moreover,the closer to the ridge,the earlier the multi-stemming occurs.Thus,also for other woody species in other forests and climate zones,ontogeny and environmental drivers promoting disturbance(not only geomorphology,but also extreme weather events,soil drought,fire),as well as soil fertility,need to be considered in combination to better understand multi-stemming and its consequences for community structure.
文摘There are gaps in our understanding of plant responses under different insect phytophagy modes and their subsequent effects on the insect herbivores＇ performance at late season. Here we compared different types of insect feeding by an aphid, Lipaphis erysimi, and a lepidopteran, Plutella xylostella, and how this affected defensive metabolites in leaves of 2 Brassica species when plants gain maturity. Thiocyanate concentrations after P xylostella and L. erysimi feeding activities were the same. Total phenolics was higher after the phloem feeder feeding than the folivore activity. The plants compensatory responses （i.e., tolerance） to L. erysimi feeding was significantly higher than the responses to P xylostella. This study showed that L. erysirni had higher carbon than P xylostella whereas nitrogen in P xylostella was 1.42 times that in L. erysimi. Population size of the phloem feeder was not affected by plant species or insect coexistence. However, there was no correlation between plant defensive metabolites and both insects＇ population size and biomass. This suggests that plant root biomass and tolerance index after different insect herbivory modes are not necessarily unidirectional. Importantly, the interaction between the folivore and the phloem feeder insects is asymmetric and the phloem feeder might be a trickier problem for plants than the folivore. Moreover, as both plants＇ common and special defenses decreased under interspecific interference, we suggest that specialist insect herbivores can be more challenged in ecosystems in which plants are not involved in interspecific interference.
基金supported by the National Key Research and Development Program of China(2017YFC0506200)the National Natural Science Foundation of China(31670429,31400346,31470712,31901149)the Royal Netherlands Academy of Arts and Sciences(KNAW,CEP grant 12CDP007)。
文摘Patterns of plant trait variation across spatial scales are important for understanding ecosystem functioning and services.However,habitat-related drivers of these patterns are poorly understood.In a conceptual model,we ask whether and how the patterns of within-and among-site plant trait variation are driven by habitat type(terrestrial vs.wetland)across large climatic gradients.We tested these through spatial-hierarchical-sampling of leaves in herbaceous-dominated terrestrial and wetland communities within each of 26 sites across China.For all 13 plant traits,within-site variation was larger than among-site variation in both terrestrial and wetland habitats.Within-site variation was similar in most leaf traits related to carbon and nutrient economics but larger in specific leaf area and size-related traits(plant height,leaf area and thickness)in wetland compared to terrestrial habitats.Among-site variation was larger in terrestrial than wetland habitats for 10 leaf traits but smaller for plant height,leaf area and leaf nitrogen.Our results indicate the important role of local ecological processes in driving plant trait variation among coexisting species and the dependence of functional variation across habitats on traits considered.These findings will help to understand and predict the effects of climatic or land-use changes on ecosystem functioning and services.
基金This work was supported by the National Natural Science Foundation of China(31870602,31901295 and 32071745)the National Key R&D Program of China(2017YFC0503906)the Program of Sichuan Excellent Youth Sci-Tech Foundation(2020JDJQ0052).
文摘Aims The redistribution of forest gaps based on solar radiation and precipitation(mainly rainfall and snowfall)can create heterogenous microenvironments inside and outside the gaps.Here,we investigated the effects of forest gaps on carbon(C),nitrogen(N)and phosphorus(P)stoichiometry in decaying logs by altering the microenvironments.Methods Minjiang fir(Abies faxoniana)logs of decay classes I–V were incubated in situ on the floor under the gap center(GC),gap edge(GE)and closed canopy(CC)in a subalpine forest in the eastern Qinghai-Tibet Plateau.The C,N and P concentrations in decaying bark,sapwood and heartwood were measured in August from 2013 to 2016.Important Findings Our results showed that the N concentration in bark decreased from the CC to the GC,while the opposite trend was found in sapwood and heartwood.Additionally,the C/N ratio in sapwood and heartwood of decay classes IV and V decreased from the CC to the GC,and the N/P ratio in heartwood of decay class V increased from the CC to the GC,implying that forest gaps have strong effects on C/N/P stoichiometry in highly decayed logs.Briefly,highly decayed logs are more susceptible to the microenvironment,and the proportion of highly decayed logs under the CC or the GC should be appropriately adjusted if necessary.
基金This study was funded by FONDECYT 3160133 to NRO and Millennium Institute of Immunology and Immunotherapy,Pontificia Universidad Católica de Chile。
文摘During vertebrate development,the immune function is inefficient and is mainly controlled by innate defense.While there have been detailed studies of various aspects of innate immune function,the effects of this function in the growth of vertebrates is still not well known.Similarly,there is little information regarding how early endotoxin exposure would affect juvenile phenotypes,specifically in a non-model mammal like a precocial rodent.We evaluated the response to an antigen and its cost in offspring of the rodent Octodon degus.We inoculated pups at 4 different ages(8,15,22 and 30 days after birth)with an antigen to determine the ontogeny and costs of the response to an endotoxin.We assessed changes in body mass,body temperature,sickness behavior and the levels of a key mediator of the inflammatory response,the cytokine interleukin-1β.We also determined the effects of early endotoxin exposure on the resting metabolic rate of juvenile animals(i.e.90 days after birth).The cytokine levels,body mass and body temperature were unaffected by time of inoculation and treatment.However,pups subjected to inoculation at 22 days after birth with the antigen showed reduced locomotion.Juvenile resting metabolic rate was not affected by early endotoxin exposure.These results suggest that the magnitude of O.degus responses would not change with age.We discuss whether the lack of effect of the response on body mass or body condition is caused by environmental variables or by the precocial characteristics of O.degus.
