Baltimore Ecosystem Study: Soil atmosphere fluxes of carbon dioxide, nitrous oxide and methane, 1998 - ongoing

The Baltimore Ecosystem Study (BES) established a network of long-term permanent biogeochemical study plots in 1998. These plots provide long-term data on vegetation, soil and hydrologic processes in the key ecosystem types within the urban ecosystem. The network of study plots includes forest plots (upland and riparian), chosen to represent the range of forest conditions in the area and grass plots (to represent home lawns). Plots are instrumented with lysimeters (drainage and tension) to sample soil solution chemistry, time domain reflectometry probes to measure soil moisture, dataloggers to measure and record soil temperature, and trace gas flux chambers to measure the flux of carbon dioxide, nitrous oxide and methane from soil to the atmosphere. Measurements of in situ nitrogen mineralization, nitrification and denitrification were made at approximately monthly intervals from Fall 1998 - Fall 2000. Detailed vegetation characterization (all layers) was done in summer 1998 and 2015. Data from these plots has been published in Groffman et al. (2006, 2009), Groffman and Pouyat (2009), Savva et al. (2010), Costa and Groffman (2013), Duncan et al. (2013), Waters et al. (2014), Ni and Groffman (2018), Templeton et al. (2019). Literature Cited Costa, K.H. and P.M. Groffman. 2013. Factors regulating net methane flux in urban forests and grasslands. Soil Science Society of America Journal 77:850 - 855. Duncan, J. M., L. E. Band, and P. M. Groffman. 2013. Towards closing the watershed nitrogen budget: Spatial and temporal scaling of denitrification. Journal of Geophysical Research Biogeosciences 118:1-5; DOI: 10.1002/jgrg.20090 Groffman PM, Pouyat RV, Cadenasso ML, Zipperer WC, Szlavecz K, Yesilonis IC,. Band LE and Brush GS. 2006. Land use context and natural soil controls on plant community composition and soil nitrogen and carbon dynamics in urban and rural forests. Forest Ecology and Management 236:177-192. Groffman, P.M., C.O. Williams, R.V. Pouyat, L.E. Band and I.C. Yesilonis. 2009. Nitrate leaching and nitrous oxide flux in urban forests and grasslands. Journal of Environmental Quality 38:1848-1860. Groffman, P.M. and R.V. Pouyat. 2009. Methane uptake in urban forests and lawns. Environmental Science and Technology 43:5229-5235. DOI: 10.1021/es803720h. Ni, X. and P.M. Groffman. 2018. Declines in methane uptake in forest soils. Proceedings of the National Academies of Science of the United States of America 115:8587-8590. Savva, Y., K. Szlavecz, R. V. Pouyat, P. M. Groffman, and G. Heisler. 2010. Effects of land use and vegetation cover on soil temperature in an urban ecosystem. Soil Science Society of America Journal 74:469-480. Templeton, L., M.L. Cadenasso, J. Sullivan, M. Neel and P.M. Groffman. 2019. Changes in vegetation structure and composition of urban and rural forest patches in Baltimore from 1998 to 2015. Forest Ecology and Management. In press. Waters, E.R., J.L. Morse, N.D. Bettez and P.M. Groffman. 2014. Differential carbon and nitrogen controls of denitrification in riparian zones and streams along an urban to exurban gradient. Journal of Environmental Quality 43:955–963.

巴尔的摩生态系统研究（Baltimore Ecosystem Study, BES）于1998年建立了长期永久生物地球化学研究样地网络。该样地网络可提供城市生态系统内关键生态系统类型中植被、土壤与水文过程的长期监测数据。
本研究的样地涵盖森林样地（包括高地与河岸带森林）与草本样地（用于表征住宅草坪生境），其中森林样地的选取覆盖了该区域范围内的各类森林立地条件。
样地配套了多种监测设备：渗漏型与张力型测渗仪（lysimeters）用于采集土壤溶液化学样品；时域反射仪探针用于测定土壤含水率；数据记录仪（dataloggers）用于监测并记录土壤温度；痕量气体通量箱则用于测定土壤向大气排放的二氧化碳、一氧化二氮与甲烷通量。
1998年秋季至2000年秋季期间，研究人员以约每月1次的频率开展了原位氮矿化、硝化与反硝化作用的测定工作。1998年与2015年夏季，研究人员完成了样地各植被层的详细特征表征。
该样地的相关研究数据已发表于以下成果：Groffman等（2006、2009）、Groffman与Pouyat（2009）、Savva等（2010）、Costa与Groffman（2013）、Duncan等（2013）、Waters等（2014）、Ni与Groffman（2018）、Templeton等（2019）。

### 参考文献
1. Costa, K.H. 与 P.M. Groffman. 2013. 城市森林与草地甲烷净通量调控因子. 《美国土壤学会杂志》77:850-855.
2. Duncan, J.M., L.E. Band 与 P.M. Groffman. 2013. 闭合流域氮预算：反硝化作用的时空尺度效应. 《地球物理研究杂志·生物地球科学分册》118:1-5; DOI: 10.1002/jgrg.20090
3. Groffman PM, Pouyat RV, Cadenasso ML, Zipperer WC, Szlavecz K, Yesilonis IC, Band LE 与 Brush GS. 2006. 城乡森林中土地利用背景与自然土壤对植物群落组成及土壤氮、碳动态的调控作用. 《森林生态与管理》236:177-192.
4. Groffman, P.M., C.O. Williams, R.V. Pouyat, L.E. Band 与 I.C. Yesilonis. 2009. 城市森林与草地中的硝酸盐淋溶与一氧化二氮通量. 《环境质量杂志》38:1848-1860.
5. Groffman, P.M. 与 R.V. Pouyat. 2009. 城市森林与草坪的甲烷吸收作用. 《环境科学与技术》43:5229-5235. DOI: 10.1021/es803720h.
6. Ni, X. 与 P.M. Groffman. 2018. 森林土壤甲烷吸收能力的下降. 《美国国家科学院院刊》115:8587-8590.
7. Savva, Y., K. Szlavecz, R.V. Pouyat, P.M. Groffman 与 G. Heisler. 2010. 土地利用与植被覆盖对城市生态系统土壤温度的影响. 《美国土壤学会杂志》74:469-480.
8. Templeton, L., M.L. Cadenasso, J. Sullivan, M. Neel 与 P.M. Groffman. 2019. 1998-2015年巴尔的摩市城乡森林斑块的植被结构与组成变化. 《森林生态与管理》（已刊印）.
9. Waters, E.R., J.L. Morse, N.D. Bettez 与 P.M. Groffman. 2014. 城乡梯度下河岸带与溪流反硝化作用的碳、氮调控差异. 《环境质量杂志》43:955–963.