Nutrients and water availability constrain the seasonality of vegetation activity in a Mediterranean ecosystem
Authors:Luo, YunpengEl-Madany, TarekMa, XuanlongNair, RichardJung, MartinWeber, UlrichFilippa, GianlucaBucher, Solveig F.Moreno, GerardoCremonese, EdoardoCarrara, ArnaudGonzalez-Cascon, RosarioEscudero, Yonatan CaceresGalvagno, MartaPacheco-Labrador, JavierPilar Martin, M.Perez-Priego, OscarReichstein, MarkusRichardson, Andrew D.Menzel, AnnetteRoemermann, ChristineMigliavacca, Mirco
Source:GLOBAL CHANGE BIOLOGY
Volume:26
Published:2020
Document Type:Article
Abstract:Anthropogenic nitrogen (N) deposition and resulting differences in ecosystem N and phosphorus (P) ratios are expected to impact photosynthetic capacity, that is, maximum gross primary productivity (GPP(max)). However, the interplay between N and P availability with other critical resources on seasonal dynamics of ecosystem productivity remains largely unknown. In a Mediterranean tree-grass ecosystem, we established three landscape-level (24 ha) nutrient addition treatments: N addition (NT), N and P addition (NPT), and a control site (CT). We analyzed the response of ecosystem to altered nutrient stoichiometry using eddy covariance fluxes measurements, satellite observations, and digital repeat photography. A set of metrics, including phenological transition dates (PTDs; timing of green-up and dry-down), slopes during green-up and dry-down period, and seasonal amplitude, were extracted from time series of GPP(max) and used to represent the seasonality of vegetation activity. The seasonal amplitude of GPP(max) was higher for NT and NPT than CT, which was attributed to changes in structure and physiology induced by fertilization. PTDs were mainly driven by rainfall and exhibited no significant differences among treatments during the green-up period. Yet, both fertilized sites senesced earlier during the dry-down period (17-19 days), which was more pronounced in the NT due to larger evapotranspiration and water usage. Fertilization also resulted in a faster increase in GPP(max) during the green-up period and a sharper decline in GPP(max) during the dry-down period, with less prominent decline response in NPT. Overall, we demonstrated seasonality of vegetation activity was altered after fertilization and the importance of nutrient-water interaction in such water-limited ecosystems. With the projected warming-drying trend, the positive effects of N fertilization induced by N deposition on GPP(max) may be counteracted by an earlier and faster dry-down in particular in areas where the N:P ratio increases, with potential impact on the carbon cycle of water-limited ecosystems.
Author Information
Corresponding Author:
Reprint Address:Luo, YP; Migliavacca, M (corresponding author), Max Planck Inst Biogeochem, Dept Biogeochem Integrat, D-07745 Jena, Germany.
Addresses:[Luo, Yunpeng; El-Madany, Tarek; Ma, Xuanlong; Nair, Richard; Jung, Martin; Weber, Ulrich; Pacheco-Labrador, Javier; Reichstein, Markus; Migliavacca, Mirco] Max Planck Inst Biogeochem, Dept Biogeochem Integrat, D-07745 Jena, Germany. [Ma, Xuanlong; Roemermann, Christine] German Ctr Integrat Biodivers Res iDiv, Leipzig, Germany. [Filippa, Gianluca; Cremonese, Edoardo; Galvagno, Marta] Environm Protect Agcy Aosta Valley, ARPA Valle Aosta, Aosta, Italy. [Bucher, Solveig F.; Roemermann, Christine] Friedrich Schiller Univ Jena, Inst Ecol & Evolut, Plant Biodivers Grp, Jena, Germany. [Bucher, Solveig F.; Reichstein, Markus; Roemermann, Christine] Michael Stifel Ctr Jena Data Driven & Simulat Sci, Jena, Germany. [Moreno, Gerardo] Univ Extremadura, Inst Dehesa Res, Plasencia, Spain. [Carrara, Arnaud] Fdn Ctr Estudios Ambientales MediterrSneo CEAM, Paterna, Spain. [Gonzalez-Cascon, Rosario] Natl Inst Agr & Food Res & Technol INIA, Dept Environm, Madrid, Spain. [Escudero, Yonatan Caceres] Univ Extremadura, Forestry Sch, Plasencia, Spain. [Pilar Martin, M.] CSIC, Environm Remote Sensing & Spect Lab SpecLab, Inst Econ Geog & Demog IEGD CCHS, Madrid, Spain. [Perez-Priego, Oscar] Macquarie Univ, Dept Biol Sci, N Ryde, NSW, Australia. [Richardson, Andrew D.] No Arizona Univ, Sch Informat Comp & Cyber Syst, Flagstaff, AZ 86011 USA. [Richardson, Andrew D.] No Arizona Univ, Ctr Ecosyst Sci & Soc, Flagstaff, AZ 86011 USA. [Menzel, Annette] Tech Univ Munich, TUM Sch Life Sci, Dept Ecol & Ecosyst Management, Freising Weihenstephan, Germany.
E-mail Addresses:yluo@bgc-jena.mpg.de; mmiglia@bgc-jena.mpg.de