Background: The demographic trade-offs(i.e. growth and survival) play important roles in forest dynamics and they are driven by multiple factors, including species’ inherent life-history strategies(such as shade-tole...Background: The demographic trade-offs(i.e. growth and survival) play important roles in forest dynamics and they are driven by multiple factors, including species’ inherent life-history strategies(such as shade-tolerance and mycorrhizal type), neighborhood interactions(such as conspecific negative density dependence, CNDD), and abiotic environment pressures. Although studies found that CNDD occurred in tropical and temperate forest,attempts to identify how the variations in CNDD control their impacts on growth and survival remain debate. In the present study, we conducted an extensive field survey, and analyzed demographic rates from 24 co-occurring temperate tree species, in order to test the importance of CNDD in shaping the growth-survival trade-offs.Results: Our study found that density dependence and environmental filtering were strong predictors for individual growth-survival trade-offs, while they showed variations across shade-intolerant and ectomycorrhizal species, as well as saplings and juveniles with more negative CNDD. Species growth showed positive relationship with mortality. And our results also support the fact that CNDD drives species growth-survival trade-offs at the community level with environmental stress.Conclusions: Our study indicates that biotic interactions such as density dependence and environment filtering played an important role in growth-survival trade-offs, and confirmed that the Janzen-Connell hypothesis in temperate forest was associated with species life-history strategies. In addition, shade-tolerance, mycorrhizal type and life-stage of forest species responded differently to CNDD, thus providing insights regarding different community assembly mechanisms and their interactions. Therefore, it is important to take species survival with growth and species life-history strategies into account when focusing on forest dynamics.展开更多
Background:Assessing functional diversity to identify its spatial patterns and drivers is an important step towards understanding the adaptive capacity of ecosystems to environmental change. However, until now, these ...Background:Assessing functional diversity to identify its spatial patterns and drivers is an important step towards understanding the adaptive capacity of ecosystems to environmental change. However, until now, these mechanisms were poorly understood in the temperate forests of northeastern China, which prevented the development of new management methods aimed at increasing functional trait diversity and thus ecological resilience.Methods:In this study, we mapped functional diversity distributions using a Kriging Interpolation Method. A specific random forest model approach was adopted to test the importance ranking of 18 variables in explaining the spatial variation of functional diversity. Three piecewise structural equation models (pSEMs) with forest types as random effects were constructed for testing the direct effects of climate, and the indirect effects of stand structure on functional diversity across the large study region. Specific causal relationships in each forest type were also examined using 15 linear structural equation models.Results:Although environmental filtering by climate is important, stand structure explains most of the functional variation of the forest ecosystems in northeastern China. Our study thus only partially supports the stressdominance hypothesis. Several abundant species determine most of the functional diversity, which supports the mass ratio hypothesis.Conclusions:Our results suggest that forest management aimed at increasing structural complexity can contribute to increased functional diversity, especially regarding the mixing of coniferous and broad-leaved tree species.展开更多
Iris pseudacorus is a widely cultivated and studied ornamental plant with a large biomass,strong adaptability and extensive management.Moreover,it has the ability to decontaminate and enrich heavy metals.However,few s...Iris pseudacorus is a widely cultivated and studied ornamental plant with a large biomass,strong adaptability and extensive management.Moreover,it has the ability to decontaminate and enrich heavy metals.However,few studies have been conducted on its submergence tolerance with little known about the molecular response of I.pseudacorus to flooding.Morphologically,I.pseudacorus had strong adaptability to waterlogging,the aerenchyma was gradually enlarged and adventitious roots developed between 0 and 14 d.The transcriptome data showed that the differentially expressed genes counts in plants flooded for 2 h,4 h,12 h and 24 h compared with the unflooded controls were 3555,9439,10734,and 4997,respectively.For GO term entries enriched by different genes,many biological processes,cell components and molecular processes in the I.pseudacorus roots were affected by flooding stress.Pathways enrichment analysis showed DEGs involved in hormone signal transduction pathways,glucose metabolism,glycolysis,and fermentation.The quantitative real-time PCR analysis of DEGs was basically consistent with the trend of transcriptome data,indicating reliability of the transcriptome data.The transcriptome analysis showed that formation of aerenchyma and adventitious roots was mainly induced by IAA(auxin)and accompanied by other hormone signals.Energy production was the primary coping mechanism of I.pseudacorus when aerenchyma was not sufficiently enlarged under water flooding.These results laid a foundation for further study on the mechanism of submerging-tolerance of I.pseudacorus and other aquatic plants.展开更多
基金supported by the Program of National Natural Science Foundation of China(No.31971650)the Key Project of National Key Research and Development Plan(No.2017YFC0504104)Beijing Forestry University Outstanding Young Talent Cultivation Project(No.2019JQ03001).
文摘Background: The demographic trade-offs(i.e. growth and survival) play important roles in forest dynamics and they are driven by multiple factors, including species’ inherent life-history strategies(such as shade-tolerance and mycorrhizal type), neighborhood interactions(such as conspecific negative density dependence, CNDD), and abiotic environment pressures. Although studies found that CNDD occurred in tropical and temperate forest,attempts to identify how the variations in CNDD control their impacts on growth and survival remain debate. In the present study, we conducted an extensive field survey, and analyzed demographic rates from 24 co-occurring temperate tree species, in order to test the importance of CNDD in shaping the growth-survival trade-offs.Results: Our study found that density dependence and environmental filtering were strong predictors for individual growth-survival trade-offs, while they showed variations across shade-intolerant and ectomycorrhizal species, as well as saplings and juveniles with more negative CNDD. Species growth showed positive relationship with mortality. And our results also support the fact that CNDD drives species growth-survival trade-offs at the community level with environmental stress.Conclusions: Our study indicates that biotic interactions such as density dependence and environment filtering played an important role in growth-survival trade-offs, and confirmed that the Janzen-Connell hypothesis in temperate forest was associated with species life-history strategies. In addition, shade-tolerance, mycorrhizal type and life-stage of forest species responded differently to CNDD, thus providing insights regarding different community assembly mechanisms and their interactions. Therefore, it is important to take species survival with growth and species life-history strategies into account when focusing on forest dynamics.
基金supported by the Program of National Natural Science Foundation of China (No. 31971650)the Key Project of National Key Research and Development Plan (No. 2017YFC0504104)Beijing Forestry University Outstanding Young Talent Cultivation Project(No. 2019JQ03001)
文摘Background:Assessing functional diversity to identify its spatial patterns and drivers is an important step towards understanding the adaptive capacity of ecosystems to environmental change. However, until now, these mechanisms were poorly understood in the temperate forests of northeastern China, which prevented the development of new management methods aimed at increasing functional trait diversity and thus ecological resilience.Methods:In this study, we mapped functional diversity distributions using a Kriging Interpolation Method. A specific random forest model approach was adopted to test the importance ranking of 18 variables in explaining the spatial variation of functional diversity. Three piecewise structural equation models (pSEMs) with forest types as random effects were constructed for testing the direct effects of climate, and the indirect effects of stand structure on functional diversity across the large study region. Specific causal relationships in each forest type were also examined using 15 linear structural equation models.Results:Although environmental filtering by climate is important, stand structure explains most of the functional variation of the forest ecosystems in northeastern China. Our study thus only partially supports the stressdominance hypothesis. Several abundant species determine most of the functional diversity, which supports the mass ratio hypothesis.Conclusions:Our results suggest that forest management aimed at increasing structural complexity can contribute to increased functional diversity, especially regarding the mixing of coniferous and broad-leaved tree species.
基金the Ph.D.Program of Sichuan Agricultural University(Grant No.63670010).
文摘Iris pseudacorus is a widely cultivated and studied ornamental plant with a large biomass,strong adaptability and extensive management.Moreover,it has the ability to decontaminate and enrich heavy metals.However,few studies have been conducted on its submergence tolerance with little known about the molecular response of I.pseudacorus to flooding.Morphologically,I.pseudacorus had strong adaptability to waterlogging,the aerenchyma was gradually enlarged and adventitious roots developed between 0 and 14 d.The transcriptome data showed that the differentially expressed genes counts in plants flooded for 2 h,4 h,12 h and 24 h compared with the unflooded controls were 3555,9439,10734,and 4997,respectively.For GO term entries enriched by different genes,many biological processes,cell components and molecular processes in the I.pseudacorus roots were affected by flooding stress.Pathways enrichment analysis showed DEGs involved in hormone signal transduction pathways,glucose metabolism,glycolysis,and fermentation.The quantitative real-time PCR analysis of DEGs was basically consistent with the trend of transcriptome data,indicating reliability of the transcriptome data.The transcriptome analysis showed that formation of aerenchyma and adventitious roots was mainly induced by IAA(auxin)and accompanied by other hormone signals.Energy production was the primary coping mechanism of I.pseudacorus when aerenchyma was not sufficiently enlarged under water flooding.These results laid a foundation for further study on the mechanism of submerging-tolerance of I.pseudacorus and other aquatic plants.
