Content of Frontier & focus: Functional traits of woody plants in our journal

Published in last 1 year |  In last 2 years |  In last 3 years |  All Please wait a minute... For Selected: Download Citations EndNote Reference Manager ProCite BibTeX RefWorks Toggle Thumbnails Select Seasonal Variations in Carbon Fluxes and Their Responses to Environmental Factors in a Pinus tabuliformis Plantation Ecosystem in Miyun, Beijing Xinhao Li,Dehuai Zhang,Zhaosen Zhang,Jian Li,Jun Cao,Jichao Wei,Xiaomeng Wu,Yun Tian,Peng Liu,Haiqun Yu Scientia Silvae Sinicae    2023, 59 (7): 35-44.   DOI: 10.11707/j.1001-7488.LYKX20220865 Abstract （267）   HTML （21）    PDF （1928KB）（401）       Knowledge map    Save Objective: This study aims to quantify carbon fluxes in plantation ecosystem and examine the role of environmental factors in regulating carbon fluxes, so as to improve the accuracy in assessing carbon sequestration function in plantation ecosystem. Method: The eddy-covariance (EC) technique was used to continuously monitor ecosystem carbon fluxes in a typical Pinus tabuliformis plantation ecosystem in Miyun, Beijing in 2021. Air temperature (Ta), vapor pressure deficit (VPD), photosynthetically active radiation (PAR), and soil water content (SWC) were continuously monitored in situ. The seasonal variation characteristics of ecosystem carbon fluxes and their responses to environmental factors were examined. Result: The cumulative annual gross ecosystem production (GEP), annual ecosystem respiration (RE), and net ecosystem production (NEP) in 2021 were 315, 291, and 24 g·m?2, respectively. GEP and RE were higher in the growing season (from April to October) and however, they were close to 0 g·m?2 in the non-growing season. The maximum daily GEP, RE, and NEP were 4.7, 3.3, and 3.1 g·m?2, respectively. The monthly maximum carbon assimilation rate was unimodal during the growing season, with its maximum in July. NEP had positive relationships with GEP (P<0.01) during the growing season and the peak growing season, and the coefficients of determination were 0.68 and 0.80, respectively. The relationships between NEP and PAR in differentTa, VPD, and SWC conditions were not significantly different. The responses of NEP and GEP to Ta, VPD, and SWC were all unimodal, peaking at about 25 ℃, 10 hPa, 0.2 m3·m–3, respectively. Low soil moisture had no significant effect on the responses of NEP and GEP to Ta and VPD, while it reduced the temperature sensitivity of RE. Conclusion: This study has found that P. tabuliformis plantation ecosystem in the study area is carbon sink during the growing season, the peak growing season, and the whole year. The change in NEP is mainly dominated by change in GEP. High Ta, VPD, and SWC all reduce NEP by limiting GEP. Low soil water condition has little indirect effect on the responses of NEP and GEP to Ta and VPD, while it limites the temperature sensitivity of RE. These results are important for further understanding of the regulations of environmental factors on the carbon cycling of P. tabuliformis plantation ecosystem under climate change. Table and Figures | Reference | Related Articles | Metrics Select Control of Environmental Factors on the Sap Flow at Daily and Seasonal Scales in Ulmus macrocarpa in Beijing, China Kai Zhang,Yanli Sun,Jichao Wei,Yaqian Fan,Xiaoxue Han,Lin Li,Xiaoshuai Wei,Xinhao Li,Peng Liu,Tianshan Zha Scientia Silvae Sinicae    2023, 59 (7): 24-34.   DOI: 10.11707/j.1001-7488.LYKX20220868 Abstract （196）   HTML （24）    PDF （2020KB）（341）       Knowledge map    Save Objective: This study was carried out to explore the responses of the sap flow and transpiration to the environmental factors at different time scales, and the result here could provide scientific support for formulating appropriate management for forest ecosystem and improve the accuracy of assessment of water conservation function of forest ecosystem. Method: The thermal diffusion method was used to continuously monitor the sap flow of Ulmus macrocarpa in Songshan, Beijing during the growing season in 2019 and 2020, and the relevant environmental variables were observed simultaneously. Linear and non-linear regressions were used to analyze abiotic control on sap flow. Result: The cumulative transpiration was 333.85 mm and 252.27 mm in 2019 and 2020, respectively, with daily means of 1.82 mm and 1.37 mm in the two years, respectively. Seasonally, the Js was controlled by shortwave radiation (Rs), air temperature (Ta), water vapor pressure deficit (VPD). The relationships between Js and Rs, Ta and VPD were significantly and positively linear, with the coefficient of determination R2 being 0.93, 0.88 and 0.89, respectively, and with a VPD threshold of 0.9 kPa in growing season. The relationship of Js and Rs was stronger (higher R2) than that with both Ta and VPD in the same month. The daily variation in Js lagged that of Rs, but preceded that of Ta and VPD. The relationships between gs and Rs, Ta, and VPD were non-linear correlation, being different from the responses of Js to environmental factors. Conclusion: There are differences between seasonal and diurnal scale in environmental control mechanism of sap flow, the changes of environmental factors affect the sap flow of plant mainly through inducing stomatal changes. The time lag between Js and environmental factors is explained by the difference in response of canopy stomatal conductance (gs) and Js to environmental factors. The time lag and sensitivity of sap flow to environmental factors can reflect drought tolerance and environmental adaptability. These results would help estimation of transpiration under similar environmental conditions and improvment of hydrological model for assessment of water conservation function of forest ecosystem. Table and Figures | Reference | Related Articles | Metrics Select Variation and Adaptation Strategies in Leaf Traits of Main Woody Plants in the Larix principis-rupprechtii Community in Baihua Mountain, Beijing Xinyue Liu,Liping Wang,Chunhe Liu,Yanli Sun,Xiaoshuai Wei,Mingze Xu,Cong Han,Yun Tian,Xin Jia,Tianshan Zha Scientia Silvae Sinicae    2023, 59 (7): 12-23.   DOI: 10.11707/j.1001-7488.LYKX20220864 Abstract （294）   HTML （20）    PDF （2135KB）（325）       Knowledge map    Save Objective: This stusy aims to examine the trade-offs between leaf traits, including chemical-, structural- and photosynthetic traits, and the relationship between leaf chemical- and structural traits and photosynthetic traits. Method: In the community, the dominant main woody species include Larix principis-rupprechtii, three broad-leaved trees, Fraxinus chinensis, Phellodendron amurense and Acer pictumsubsp.mono, and two shrubs, Lespedeza bicolorand Spiraea salicifolia. The 13 leaf traits were measured for the woody species in the L. principis-rupprechtii community in Bahushan, Beijing using portable analyzer during July-August in 2021. Photosynthetic traits included maximum net photosynthetic rate (Pnmax), saturation irradiance (Isat), dark respiration rate (Rd), saturation intercellular CO2 concentration (Cisat), maximum rate of carboxylation (Vcmax), maximum potential rate of electron transport (Jmax), water use efficiency (WUE), and photosynthetic nitrogen-use efficiency (PNUE). The structural traits were leaf thickness (LT), specific leaf area (SLA), and leaf tissue density (LTD). The chemical traits were carbon-nitrogen ratio (C∶N), and nitrogen-phosphorus ratio (N∶P). One-way analysis of variance, Spearman correlation analysis, principal component analysis and linear regression were used to analyze the correlation of leaf traits and the effects of leaf chemical and structural traits on photosynthetic traits in the L. principis-rupprechtii community. Result: 1) The PNUE and SLA showed the largest inter-species variation with variation coefficient of 60.88% and 56.83%, respectively, indicating that the species in the commnuity competed for light resource. 2) Shrubs had higher SLA in order to increase light acquisition ability on vertical structure in the community. Meanwhile, N∶P in tree leaves was 14.58, while that in shrub leaves was 21.10. Compared with trees, shrubs had lower C∶N, but higher N∶P, indicating that the shrub allocated more nitrogen into leaf to obtain light and maintain growth. 3) C∶N, N∶P and SLA were 18.19, 16.04 and 193.77 cm2·g?1 in broad-leaved trees, respectively, and were 39.6, 10.2 and 82.2 cm2·g?1 in needle-leaved trees, respectively. Compared with broad-leaved trees, the needle-leaved trees had higher C∶N, but lower N∶P and SLA, indicating that the needle-leaved trees tended to construct the more defensive organization and had higher resistance to stress and lower light interception capability. 4) L. principis-rupprechtii was located at “slow investment-return”, shrubs were at “fast investment-return” in leaf economic spectrum. L. principis-rupprechtii had higher WUE but lower PNUE, suggesting that the trade-off between WUE and PNUE occurred, with WUE increasing at the expense of PNUE. 5) Compared with other broad-leaved trees and shrubs, the Pnmax of A. pictum subsp. mono and S. salicifolia were not obviously higher, but the Rd were significantly lower than other species. 6) The Isat, Rd WUE and PNUE were significantly correlated with C∶N, LT and SLA (P<0.05). Conclusion: These results suggest that there is obvious leaf economics spectrum existed across the woody species in the community, and the interspecific competition is mainly for light resource. Although A. pictum subsp. mono and S. salicifolia are not the dominant species in the community, their net carbon sequestration capacity in per unit area is stronger than other species. The C∶N, LT and SLA can be used as the indicators predicting the photosynthetic capacity. Species with higher C∶N, LT and lower SLA have higher tolerance to strong light and higher water use efficiency, but have stronger utilization of weak light and less carbon consumption. Meanwhile, photosynthetic nitrogen utilization efficiency is lower. The results can provide theoretical support for subsequent forest management. Table and Figures | Reference | Related Articles | Metrics Select Seasonal Variation and Environmental Control of Leaf Resource Use Efficiencies of an Understory Shrub, Rhamnus parvifolia in Pinus tabuliformis Forest in Miyun, Beijing Hongxian Zhao,Tong Su,Ruifu Wang,Yanli Sun,Yonglong Gao,Jichao Wei,Xinhao Li,Yun Tian,Xin Jia,Tianshan Zha Scientia Silvae Sinicae    2023, 59 (7): 1-11.   DOI: 10.11707/j.1001-7488.LYKX20220867 Abstract （321）   HTML （23）    PDF （1480KB）（302）       Knowledge map    Save Objective: This study aims to clarify the trade-offs between light, nitrogen and water use efficiency (RUEs) in the leaves of the understorey shrub Rhamnus parvifoliaand their environmental regulation mechanisms. Method: We analyzed the seasonal dynamics of intrinsic water use efficiency (WUEi), nitrogen use efficiency (NUE) and light use efficiency (LUE) as well as the trade-offs among RUEs of a dominant understory shrub, R. parvifolia, leaves through season-long in-situ measurements of the light response curve and leaf functional traits along with simultaneous environmental measurements from June to October, 2021 in Miyun, Beijing, China. Result: 1) The result showed that the maximum WUEi, NUE, and LUE in growing season fluctuated with values of 107.3 μmol·mol?1, 18.35 μmol·g?1s?1, and 0.087 mol·mol?1, respectively, with coefficient of variation (CV) being 24.91%, 39.12%, and 12.6%. 2) In the middle of the growing season, under the wet condition with relative extractable soil water (REW) greater than 0.4, there were higher NUE and lower WUEi. The NUE had opposite trend to WUEi (P < 0.05) and varied synergistically with LUE ( P < 0.05). 3) The WUE i was positively correlated with leaf mass per unit area (LMA) (P < 0.05) and negatively correlated with transpiration rate (Tr, P < 0.05), while NUE was negatively correlated with LMA and leaf thickness (LT, P < 0.05) and positively correlated with Tr ( P < 0.05). Increases in air temperature ( Ta), photosynthetically active radiation (PAR) and diffuse radiation (Rdif) all contributed to increased LUE (P < 0.05). Conclusion: It has been found that WUEi and NUE are decoupled from soil water content and closely relate to LMA and Tr in wet period and limited light. Increasing radiation and Ta promotes the light utilization efficiency of leaf, and diffuse radiation raises the photosynthetic capacity of leaf. There is a trade-off between RUEs. The NUE and WUEi can not simultaneously maximize in the growing season, but under wet condition and low light, NUE and LUE change in the same direction, both fluctuating in the middle of the growing season and gradually decrease at the end of the growing season. The results of this study are important additions to the in-depth understanding of the adaptation strategies of temperate plant communities under climate change. Table and Figures | Reference | Related Articles | Metrics