1
|
Xia H, Xu X, Xu J, Huang Y, Jiang H, Xu X, Zhang T. Warming, rather than drought, remains the primary factor limiting carbon sequestration. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 907:167755. [PMID: 37832680 DOI: 10.1016/j.scitotenv.2023.167755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 10/09/2023] [Accepted: 10/10/2023] [Indexed: 10/15/2023]
Abstract
Steppe ecosystems in arid and semiarid regions are particularly sensitive to climate change and strongly regulate the global carbon balance. However, carbon fluxes respond differently to climate change in different growing seasons, and the mechanism of this control is not yet clear. Therefore, we (i) obtained carbon flux data observed by a field eddy station in Inner Mongolia from 2006 to 2021; (ii) investigated the constraint effects of climatic factors on carbon fluxes; (iii) explored the response mechanisms of carbon fluxes to coupled changes in temperature and moisture; (iv) investigated the adaptation of steppe ecosystem to changes in temperature and drought. The results showed that (i) the steppe ecosystem was a carbon sink, with an average annual carbon fixation of 73.55 g C m-2 yr-1 and a roughly N-shaped carbon sink accumulation process within one year. (ii) The constraint effect of temperature and Vapor Pressure Deficit (VPD) on Net Ecosystem Productivity (NEP) and Gross Primary Productivity (GPP) was parabolic, with a clear optimum point. (iii) Temperature and moisture in the soil played a greater role in ecosystem carbon sequestration. Soil Water Content (SWC) could alleviate the inhibitory effect of temperature changes on the carbon sequestration of ecosystem. (iv) This ecosystem was capable of adapting well to changes in temperature and drought. However, warming, rather than drought, remains the primary factor limiting carbon sequestration. Specifically, it was GPP that drives the adaptation of ecosystem carbon sequestration to changes in temperature and drought, rather than Ecosystem Respiration (RECO). Although the steppe ecosystem has a good adaptation to changes in temperature and drought, it is still in the boundary region of warming. We hope that our study will deepen our comprehensive understanding of the relationship between temperature and moisture and ecosystem carbon fluxes and provide evidence for steppe ecosystem adaptation to climate change.
Collapse
Affiliation(s)
- Haoyu Xia
- State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing, China; Faculty of Geographical Science, Beijing Normal University, Beijing, China
| | - Xia Xu
- State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing, China; Faculty of Geographical Science, Beijing Normal University, Beijing, China.
| | - Jiayu Xu
- State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing, China; Faculty of Geographical Science, Beijing Normal University, Beijing, China
| | - Yiqin Huang
- State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing, China; Faculty of Geographical Science, Beijing Normal University, Beijing, China
| | - Honglei Jiang
- Guangxi Laboratory on the Study of Coral Reefs in the South China Sea, Coral Reef Research Centre of China, School of Marine Sciences, Guangxi University, Nanning, China
| | - Xiaoqing Xu
- State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing, China; Faculty of Geographical Science, Beijing Normal University, Beijing, China
| | - Tong Zhang
- State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing, China; Faculty of Geographical Science, Beijing Normal University, Beijing, China
| |
Collapse
|
2
|
Zhou B, Sterck F, Kruijt B, Fan ZX, Zuidema PA. Diel and seasonal stem growth responses to climatic variation are consistent across species in a subtropical tree community. THE NEW PHYTOLOGIST 2023; 240:2253-2264. [PMID: 37737019 DOI: 10.1111/nph.19275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 09/04/2023] [Indexed: 09/23/2023]
Abstract
Understanding how intra-annual stem growth responds to atmospheric and soil conditions is essential for assessing the effects of climate extremes on forest productivity. In species-poor forests, such understanding can be obtained by studying stem growth of the dominant species. Yet, in species-rich (sub-)tropical forests, it is unclear whether these responses are consistent among species. We monitored intra-annual stem growth with high-resolution dendrometers for 27 trees belonging to 14 species over 5 yr in a montane subtropical forest. We quantified diel and seasonal stem growth patterns, verified to what extent observed growth patterns coincide across species and analysed their main climatic drivers. We found very consistent intra-annual growth patterns across species. Species varied in the rate but little in the timing of growth. Diel growth patterns revealed that - across species - trees mainly grew before dawn when vapour pressure deficit (VPD) was low. Within the year, trees mainly grew between May and August driven by temperature and VPD, but not by soil moisture. Our study reveals highly consistent stem growth patterns and climatic drivers at community level. Further studies are needed to verify whether these results hold across climates and forests, and whether they can be scaled up to estimate forest productivity.
Collapse
Affiliation(s)
- Bo Zhou
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, 666303, China
- Forest Ecology and Forest Management Group, Wageningen University and Research, Wageningen, 6700 AA, the Netherlands
| | - Frank Sterck
- Forest Ecology and Forest Management Group, Wageningen University and Research, Wageningen, 6700 AA, the Netherlands
| | - Bart Kruijt
- Water Systems and Global Change Group, Wageningen University and Research, Wageningen, 6700 AA, the Netherlands
| | - Ze-Xin Fan
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, 666303, China
- Ailaoshan Station for Subtropical Forest Ecosystem Studies, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Jingdong, Yunnan, 676209, China
| | - Pieter A Zuidema
- Forest Ecology and Forest Management Group, Wageningen University and Research, Wageningen, 6700 AA, the Netherlands
| |
Collapse
|
3
|
Species and Competition Interact to Influence Seasonal Stem Growth in Temperate Eucalypts. FORESTS 2022. [DOI: 10.3390/f13020224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Insights on tree species and competition effects on seasonal stem growth are critical to understanding the impacts of changing climates on tree productivity, particularly for eucalypts species that occur in narrow climatic niches and have unreliable tree rings. To improve our understanding of climate effects on forest productivity, we examined the relative importance of species, competition and climate to the seasonal stem growth of co-occurring temperate eucalypts. We measured monthly stem growth of three eucalypts (Eucalyptus obliqua, E. radiata, and E. rubida) over four years in a natural mixed-species forest in south-eastern Australia, examining the relative influences of species, competition index (CI) and climate variables on the seasonal basal area increment (BAI). Seasonal BAI varied with species and CI, and was greatest in spring and/or autumn, and lowest in summer. Our study highlights the interactive effects of species and competition on the seasonal stem growth of temperate eucalypts, clearly indicating that competitive effects are strongest when conditions are favourable to growth (spring and autumn), and least pronounced in summer, when reduced BAI was associated with less rainfall. Thus, our study indicates that management to reduce inter-tree competition would have minimal influence on stem growth during less favourable (i.e., drier) periods.
Collapse
|
4
|
Bennett AC, Arndt SK, Bennett LT, Knauer J, Beringer J, Griebel A, Hinko-Najera N, Liddell MJ, Metzen D, Pendall E, Silberstein RP, Wardlaw TJ, Woodgate W, Haverd V. Thermal optima of gross primary productivity are closely aligned with mean air temperatures across Australian wooded ecosystems. GLOBAL CHANGE BIOLOGY 2021; 27:4727-4744. [PMID: 34165839 DOI: 10.1111/gcb.15760] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 06/15/2021] [Accepted: 06/19/2021] [Indexed: 06/13/2023]
Abstract
Gross primary productivity (GPP) of wooded ecosystems (forests and savannas) is central to the global carbon cycle, comprising 67%-75% of total global terrestrial GPP. Climate change may alter this flux by increasing the frequency of temperatures beyond the thermal optimum of GPP (Topt ). We examined the relationship between GPP and air temperature (Ta) in 17 wooded ecosystems dominated by a single plant functional type (broadleaf evergreen trees) occurring over a broad climatic gradient encompassing five ecoregions across Australia ranging from tropical in the north to Mediterranean and temperate in the south. We applied a novel boundary-line analysis to eddy covariance flux observations to (a) derive ecosystem GPP-Ta relationships and Topt (including seasonal analyses for five tropical savannas); (b) quantitatively and qualitatively assess GPP-Ta relationships within and among ecoregions; (c) examine the relationship between Topt and mean daytime air temperature (MDTa) across all ecosystems; and (d) examine how down-welling short-wave radiation (Fsd) and vapour pressure deficit (VPD) influence the GPP-Ta relationship. GPP-Ta relationships were convex parabolas with narrow curves in tropical forests, tropical savannas (wet season), and temperate forests, and wider curves in temperate woodlands, Mediterranean woodlands, and tropical savannas (dry season). Ecosystem Topt ranged from 15℃ (temperate forest) to 32℃ (tropical savanna-wet and dry seasons). The shape of GPP-Ta curves was largely determined by daytime Ta range, MDTa, and maximum GPP with the upslope influenced by Fsd and the downslope influenced by VPD. Across all ecosystems, there was a strong positive linear relationship between Topt and MDTa (Adjusted R2 : 0.81; Slope: 1.08) with Topt exceeding MDTa by >1℃ at all but two sites. We conclude that ecosystem GPP has adjusted to local MDTa within Australian broadleaf evergreen forests and that GPP is buffered against small Ta increases in the majority of these ecosystems.
Collapse
Affiliation(s)
- Alison C Bennett
- School of Ecosystem and Forest Science, University of Melbourne, Richmond, Vic., Australia
| | - Stefan K Arndt
- School of Ecosystem and Forest Science, University of Melbourne, Richmond, Vic., Australia
| | - Lauren T Bennett
- School of Ecosystem and Forest Science, University of Melbourne, Creswick, Vic., Australia
| | - Jürgen Knauer
- CSIRO, Oceans and Atmosphere, Canberra, ACT, Australia
| | - Jason Beringer
- School of Agriculture and Environment, The University of Western Australia, Crawley, WA, Australia
| | - Anne Griebel
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - Nina Hinko-Najera
- School of Ecosystem and Forest Science, University of Melbourne, Creswick, Vic., Australia
| | - Michael J Liddell
- Centre for Tropical Environmental and Sustainability Science and College of Science and Engineering, James Cook University, Cairns, Qld, Australia
| | - Daniel Metzen
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - Elise Pendall
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - Richard P Silberstein
- School of Agriculture and Environment, The University of Western Australia, Crawley, WA, Australia
- Centre for Ecosystem Management, School of Science, Edith Cowan University, Joondalup, WA, Australia
| | - Timothy J Wardlaw
- ARC Centre for Forest Value, University of Tasmania, Hobart, TAS, Australia
| | - William Woodgate
- CSIRO, Land and Water, Canberra, ACT, Australia
- School of Earth and Environmental Sciences, The University of Queensland, St Lucia, Qld, Australia
| | | |
Collapse
|