CO2 Flux Characteristics of Different Plant Communities in a Subtropical Urban Ecosystem

Abstract

Shanghai, China, is a city that is relatively representative of various cities in China due to its geographical location and socio-economic dynamics. The role of urban vegetation in the carbon cycle of urban developments in these types of cities is now being studied. We focus on identifying which urban plant community types have a greater influence on CO2 flux in cities, thus providing a scientific basis for low-carbon urban greening. Based on the eddy covariance (EC) observation system, ART Footprint Tool, plant inventory, and ecological community classification, we show that the CO2 flux characteristics of different plant communities vary temporally. The carbon sink duration during summer was the longest (up to 10 h) and the carbon sink duration was the shortest during winter (7.5 h). In addition, we discovered that the CO2 flux contribution rates of different plant community types are distinct. The annual average CO2 contribution rates of the Cinnamomum camphora-Trachycarpus fortunei community and the Metasequoia glyptostroboides+Sabina chinensis community are 11.88% and 0.93%, respectively. The CO2 flux contribution rate of the same plant community differs according to season. The CO2 contribution rate of the Cinnamomum camphora-Trachycarpus fortunei community exhibits local maxima during winter and summer, with a maximum difference of 11.16%. In contrast, the Metasequoia glyptostroboides+Sabina chinensis community has a CO2 contribution rate of 0.35% during the same period. In general, summer is the season with the lowest CO2 flux contribution rate of plant communities, and winter is the season with the highest CO2 flux contribution rate. However, the Cinnamomum camphora+Salix babylonica community and the Cinnamomum camphora+Sabina chinensis community present the opposite pattern. Finally, the diurnal variation characteristics of CO2 flux in different communities have the same trend, but the peak values differ significantly. Overall, daily CO2 flux peak value of the Metasequoia glyptostroboides community and the Cinnamomum camphora-Trachycarpus fortunei community indicate that these two plant communities exhibit a strong capacity for CO2 absorption in the study area. According to these research results, urban greening efforts in subtropical climates can increase the green space covered by the Cinnamomum camphora-Trachycarpus fortunei and the Metasequoia glyptostroboides community types when urban greening, so as to appropriately reduce the CO2 emitted into the atmosphere.

Spatiotemporal Modeling of Carbon Fluxes over Complex Underlying Surfaces along the North Shore of Hangzhou Bay

“…The study area is flat and located in the mid-temperate zone geographically, with a subtropical monsoon climate. The prevailing wind direction is southeast, and the climate is humid and mild [21]. The annual average temperature stands at around 16.1 • C, with an annual rainfall of approximately 1191.5 mm.…”

“…The eddy covariance flux observation tower (EC tower, 121 • 30 ′ 38.96 ′′ E, 30 • 50 ′ 32.26 ′′ N) is located in Fengxian Bay University City, Shanghai. CO 2 flux was measured using an open-path eddy covariance (OPEC) system, which consisted of an open-path and fastresponse infrared gas analyzer (Model LI-7500, Li-Cor Inc., Lincoln, NE, USA) to monitor the densities of CO 2 and H 2 O, and a 3D sonic anemometer (Model WindMaster Pro, Gill Instruments Ltd., Lymington, UK) to measure the fluctuations of three-dimensional wind speed and virtual temperature [21]. The height of EC monitoring was 20 m. The raw data were recorded and saved to a data logger (Model CR 3000, Campell Scientific Inc., North Logan, UT, USA) (Figure 1).…”

Future Reductions in Suitable Habitat for Key Tree Species Result in Declining Boreal Forest Aboveground Biomass Carbon in China

“…In addition, L. gmelinii habitats provide a diverse range of support for various organisms, including endemic species, and any alterations to the habitat would impact their distribution [22]. Similarly, Schima superba Gardner & Champ (S. superba) and Camphora officinarum (C. officinarum) are dominant evergreen broad-leaved tree species widely distributed in China's SEBF, with a high capacity for CO 2 absorption [23][24][25]. Therefore, L. gmelinii serve as the typical tree species of TCBMF, while S. superba and C. officinarum represent typical tree species for SEBF in this study.…”

Multi-Sensor Classification Framework of Urban Vegetation for Improving Ecological Services Management

“…Contrarily, the entire urban GI system may function as a net CO 2 source, introducing complexity to its environmental impact [10]. This intricate interplay is influenced by diverse factors, including climate variations [11], vegetation types [12,13], soil characteristics [14], and management practices (such as irrigation, pest control, and maintenance) [14]. Despite vegetation's role as a clear CO 2 sink through photosynthesis [15], soil CO 2 fluxes can counterbalance this effect, potentially increasing overall CO 2 emissions [14].…”