B002-0015
Response of a rubber plant functional type in the Community Land Model (CLM5) to inter-annual variations in climate and nitrogen fertilization rates
Monday, 7 December 2020
Poster
Ashehad Ali1, Yuanchao Fan2, Christian Stiegler3, Andi Nur Cahyo4, Marife D Corre5, Fernando Moyano6, Martyna Kotowska1, Ana Meijide7, Rahmi Ariani6, Tania June8, Suria Tarigan9, Holger Kreft10, Dirk Hölscher11, Chonggang Xu12, Charles Koven13, Katherine Dagon14, Rosie Fisher14, Edzo Veldkamp5 and Alexander Knohl1, (1)University of Göttingen, Göttingen, Germany, (2)Harvard University, Cambridge, MA, United States, (3)University of Göttingen, Bioclimatology, Göttingen, Germany, (4)Indonesian Rubber Research Institute, Sembawa, Indonesia, (5)University of Göttingen, Soil Science of Tropical and Subtropical Ecosystems, Göttingen, Germany, (6)Georg-August-Universitaet Goettingen, Bioclimatology, Goettingen, Germany, (7)University of Göttingen, Crop Sciences, Göttingen, Germany, (8)Bogor Agricultural University (IPB), Department of Geophysics and Meteorology, Bogor, Indonesia, (9)Bogor Agricultural University, Department of Soil and Natural Resources Management, Bogor, Indonesia, (10)University of Göttingen, Biodiversity, Macroecology & Biogeography, Göttingen, Germany, (11)University of Göttingen, Tropical Silviculture and Forest Ecology, Göttingen, Germany, (12)Los Alamos National Laboratory, Los Alamos, NM, United States, (13)Lawrence Berkeley National Laboratory, Berkeley, CA, United States, (14)National Center for Atmospheric Research, Boulder, CO, United States
Abstract:
Drought and nitrogen (N) limitations are major constraints on growth and yields of rubber. Although empirical data support this notion, an understanding of the processes associated with the response of rubber to drought and nitrogen is lacking. Thus, in this study, we used the Community Land Model that has implemented parameterization and functions for a rubber plant functional type (CLM5-rubber) to investigate how rubber plantations respond to inter-annual variations in climate and changes in nitrogen fertilization rates at a mature rubber plantation site in Indonesia. Using CLM5-rubber, we also examined how an immature rubber plantation from Cambodia responded to nitrogen fertilization rates. In our simulations, we covered the period 2014 to 2016, which included the 2015 drought associated with El Nino-Southern Oscillation (ENSO) event, the strongest of the last decades.
CLM5-rubber predicted about a 20% decline in latex yield in response to ENSO in the dry season while the measurements indicated a 36% decline during the same period at the matured rubber plantation site in Indonesia. CLM5-rubber largely captured the seasonality of the measured soil moisture but did not capture much the magnitude. CLM5-rubber predicted the highest correlation between stomatal conductance and soil moisture during the ENSO year, suggesting that ENSO increases the coupling between the two and that soil water limitation downregulates photosynthesis and productivity.
In the case of N fertilization, modeled latex yield of a matured rubber plantation site in Indonesia reproduced reasonably the observed impacts of N fertilization after three years. Surprisingly, there was no difference between CLM5-rubber and measurements for leaf nitrogen concentrations in the beginning of the field experiment or in the beginning of the model simulation at the site in Indonesia. Modeled latex yield of immature rubber plantation at a site in Cambodia was not sensitive to N fertilization, but was sensitive to the initial value of soil CN, suggesting that it is important to know the land-use type that existed prior to planting, the dynamics of N demand and C and N allocation strategy of rubber depending on its age, and the implications soil carbon-nitrogen has for latex yield in the medium- and long-term time scales.
