Browsing by Subject "FOREST ECOSYSTEMS"

Sort by: Order: Results:

Now showing items 1-5 of 5
  • Fernandez-Martinez, M.; Vicca, S.; Janssens, I. A.; Ciais, P.; Obersteiner, M.; Bartrons, M.; Sardans, J.; Verger, A.; Canadell, J. G.; Chevallier, F.; Wang, X.; Bernhofer, C.; Curtis, P. S.; Gianelle, D.; Gruewald, T.; Heinesch, B.; Ibrom, A.; Knohl, A.; Laurila, T.; Law, B. E.; Limousin, J. M.; Longdoz, B.; Loustau, D.; Mammarella, I.; Matteucci, G.; Monson, R. K.; Montagnani, L.; Moors, E. J.; Munger, J. W.; Papale, D.; Piao, S. L.; Penuelas, J. (2017)
    Concentrations of atmospheric carbon dioxide (CO2) have continued to increase whereas atmospheric deposition of sulphur and nitrogen has declined in Europe and the USA during recent decades. Using time series of flux observations from 23 forests distributed throughout Europe and the USA, and generalised mixed models, we found that forest-level net ecosystem production and gross primary production have increased by 1% annually from 1995 to 2011. Statistical models indicated that increasing atmospheric CO2 was the most important factor driving the increasing strength of carbon sinks in these forests. We also found that the reduction of sulphur deposition in Europe and the USA lead to higher recovery in ecosystem respiration than in gross primary production, thus limiting the increase of carbon sequestration. By contrast, trends in climate and nitrogen deposition did not significantly contribute to changing carbon fluxes during the studied period. Our findings support the hypothesis of a general CO2-fertilization effect on vegetation growth and suggest that, so far unknown, sulphur deposition plays a significant role in the carbon balance of forests in industrialized regions. Our results show the need to include the effects of changing atmospheric composition, beyond CO2, to assess future dynamics of carbon-climate feedbacks not currently considered in earth system/climate modelling.
  • Li, Quan; Song, Xinzhang; Yrjälä, Kim; Lv, Jianhua; Li, Yongfu; Wu, Jiasheng; Qin, Hua (2020)
    Increased reactive N deposition has widespread effects on terrestrial ecosystems, such as biodiversity loss, soil acidification, as well as stimulated plant growth. Empirical studies show that biochar often affects soil quality, crop productivity, soil microbial community composition and enzyme activities. However, the effect of biochar addition on forest soil bacterial community along with enzyme activities under nitrogen (N) deposition and its related mechanisms have not been well studied yet. Therefore, a 2-year field study was conducted to investigate the effects of biochar amendment (0, 20, 40 kg biochar ha−1 yr−1) on soil nutrients, enzyme activities, and bacterial community in a Torreya grandis orchard under different levels of N deposition (0, 30, 60 kg N ha−1 yr−1). N deposition significantly increased soil nutrients availability, such as N, phosphorus (P) and potassium (K), while biochar amendment led to significant increase in soil pH, organic carbon (SOC), total N (TN), total P (TP), available P (AP) and available K (AK). Both N deposition and biochar amendment significantly decreased the soil microbial biomass carbon (MBC), altered soil microbial community and enzyme activities significantly. Biochar addition increased the relative abundance of phylum Proteobacteria under different levels of N deposition, but had variable effect on Acidobacteria groups. Non-metric multidimensional scaling (NMDS) indicated that biochar amendment can mitigate the effect of N deposition on soil bacterial community composition and enzyme activities. Soil pH and SOC played an important role in shaping soil bacterial community composition, while available AP and AK contents significantly related to the variation of soil enzyme activities. Structure equation modeling (SEM) revealed that N deposition had negative effect on soil enzyme activities while biochar amendment can mitigate this negative effect through increasing AP content. Our result suggests that biochar amendment can mitigate the alteration of soil bacterial community and enzyme activities induced by N deposition, and this mitigation effect was linked to the alteration of soil physicochemical properties, especially the increased AP content. Thus, biochar amendment could be a promising way to develop sustainable forest management under increasing N deposition.
  • Knyazikhin, Yuri; Schull, Mitchell A.; Stenberg, Pauline; Mõttus, Matti; Rautiainen, Miina; Yang, Yan; Marshak, Alexander; Latorre Carmona, Pedro; Kaufmann, Robert K.; Lewis, Philip; Disney, Mathias I.; Vanderbilt, Vern; Davis, Anthony B.; Baret, Frederic; Jacquemoud, Stephane; Lyapustin, Alexei; Myneni, Ranga B. (2013)
  • Salmon, Yann; Li, Xuefei; Yang, Bo; Ma, Keping; Siegwolf, Rolf T. W.; Schmid, Bernhard (2018)
    Increasing biodiversity has been linked to higher primary productivity in terrestrial ecosystems. However, the underlying ecophysiological mechanisms remain poorly understood. We investigated the effects of surrounding species richness (monoculture, two- and four-species mixtures) on the ecophysiology of Lithocarpus glaber seedlings in experimental plots in subtropical China. A natural rain event isotopically labelled both the water uptaken by the L.glaber seedlings and the carbon in new photoassimilates through changes of photosynthetic discrimination. We followed the labelled carbon (C) and oxygen (O) in the plant-soil-atmosphere continuum. We measured gas-exchange variables (C assimilation, transpiration and above- and belowground respiration) and C-13 in leaf biomass, phloem, soil microbial biomass, leaf- and soil-respired CO2 as well as O-18 in leaf and xylem water. The C-13 signal in phloem and respired CO2 in L.glaber in monoculture lagged behind those in species mixture, showing a slower transport of new photoassimilates to and through the phloem in monoculture. Furthermore, leaf-water O-18 enrichment above the xylem water in L.glaber increased after the rain in lower diversity plots suggesting a lower ability to compensate for increased transpiration. Lithocarpus glaber in monoculture showed higher C assimilation rate and water-use efficiency. However, these increased C resources did not translate in higher growth of L.glaber in monoculture suggesting the existence of larger nongrowth-related C sinks in monoculture. These ecophysiological responses of L.glaber, in agreement with current understanding of phloem transport are consistent with a stronger competition for water resources in monoculture than in species mixtures. Therefore, increasing species diversity in the close vicinity of the studied plants appears to alleviate physiological stress induced by water competition and to counterbalance the negative effects of interspecific competition on assimilation rates for L.glaber by allowing a higher fraction of the C assimilated to be allocated to growth in species mixture than in monoculture.
  • Franz, Daniela; Acosta, Manuel; Altimir, Nuria; Arriga, Nicola; Arrouays, Dominique; Aubinet, Marc; Aurela, Mika; Ayres, Edward; Lopez-Ballesteros, Ana; Barbaste, Mireille; Berveiller, Daniel; Biraud, Sebastien; Boukir, Hakima; Brown, Timothy; Bruemmer, Christian; Buchmann, Nina; Burba, George; Carrara, Arnaud; Cescatti, Allessandro; Ceschia, Eric; Clement, Robert; Cremonese, Edoardo; Crill, Patrick; Darenova, Eva; Dengel, Sigrid; D'Odorico, Petra; Filippa, Gianluca; Fleck, Stefan; Fratini, Gerardo; Fuss, Roland; Gielen, Bert; Gogo, Sebastien; Grace, John; Graf, Alexander; Grelle, Achim; Gross, Patrick; Gruenwald, Thomas; Haapanala, Sami; Hehn, Markus; Heinesch, Bernard; Heiskanen, Jouni; Herbst, Mathias; Herschlein, Christine; Hortnagl, Lukas; Hufkens, Koen; Ibrom, Andreas; Jolivet, Claudy; Joly, Lilian; Jones, Michael; Kiese, Ralf; Klemedtsson, Leif; Kljun, Natascha; Klumpp, Katja; Kolari, Pasi; Kolle, Olaf; Kowalski, Andrew; Kutsch, Werner; Laurila, Tuomas; de Ligne, Anne; Linder, Sune; Lindroth, Anders; Lohila, Annalea; Longdoz, Bernhard; Mammarella, Ivan; Manise, Tanguy; Maranon Jimenez, Sara; Matteucci, Giorgio; Mauder, Matthias; Meier, Philip; Merbold, Lutz; Mereu, Simone; Metzger, Stefan; Migliavacca, Mirco; Molder, Meelis; Montagnani, Leonardo; Moureaux, Christine; Nelson, David; Nemitz, Eiko; Nicolini, Giacomo; Nilsson, Mats B.; Op de Beeck, Maarten; Osborne, Bruce; Lofvenius, Mikaell Ottosson; Pavelka, Marian; Peichl, Matthias; Peltola, Olli; Pihlatie, Mari; Pitacco, Andrea; Pokorny, Radek; Pumpanen, Jukka; Ratie, Celine; Rebmann, Corinna; Roland, Marilyn; Sabbatini, Simone; Saby, Nicolas P. A.; Saunders, Matthew; Schmid, Hans Peter; Schrumpf, Marion; Sedlak, Pavel; Serrano Ortiz, Penelope; Siebicke, Lukas; Sigut, Ladislav; Silvennoinen, Hanna; Simioni, Guillaume; Skiba, Ute; Sonnentag, Oliver; Soudani, Kamel; Soule, Patrice; Steinbrecher, Rainer; Tallec, Tiphaine; Thimonier, Anne; Tuittila, Eeva-Stiina; Tuovinen, Juha-Pekka; Vestin, Patrik; Vincent, Gaelle; Vincke, Caroline; Vitale, Domenico; Waldner, Peter; Weslien, Per; Wingate, Lisa; Wohlfahrt, Georg; Zahniser, Mark; Vesala, Timo (2018)
    Research infrastructures play a key role in launching a new generation of integrated long-term, geographically distributed observation programmes designed to monitor climate change, better understand its impacts on global ecosystems, and evaluate possible mitigation and adaptation strategies. The pan-European Integrated Carbon Observation System combines carbon and greenhouse gas (GHG; CO2, CH4, N2O, H2O) observations within the atmosphere, terrestrial ecosystems and oceans. High-precision measurements are obtained using standardised methodologies, are centrally processed and openly available in a traceable and verifiable fashion in combination with detailed metadata. The Integrated Carbon Observation System ecosystem station network aims to sample climate and land-cover variability across Europe. In addition to GHG flux measurements, a large set of complementary data (including management practices, vegetation and soil characteristics) is collected to support the interpretation, spatial upscaling and modelling of observed ecosystem carbon and GHG dynamics. The applied sampling design was developed and formulated in protocols by the scientific community, representing a trade-off between an ideal dataset and practical feasibility. The use of open-access, high-quality and multi-level data products by different user communities is crucial for the Integrated Carbon Observation System in order to achieve its scientific potential and societal value.