Browsing by Subject "Tropical forests"

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  • Maeda, Eduardo; Nunes, Matheus; Calders, Kim; Mendes de Moura, Yhasmin; Raumonen, Pasi; Tuomisto, Hanna; Verley, Philippe; Vincent, Gregoire; Zuquin, Gabriela; Camargo, José Luis (2022)
    Forest edges are an increasingly common feature of Amazonian landscapes due to human-induced forest frag-mentation. Substantial evidence shows that edge effects cause profound changes in forest biodiversity and productivity. However, the broader impacts of edge effects on ecosystem functioning remain unclear. Assessing the three-dimensional arrangement of forest elements has the potential to unveil structural traits that are scalable and closely linked to important functional characteristics of the forest. Using over 600 high-resolution terrestrial laser scanning measurements, we present a detailed assessment of forest structural metrics linked to ecosystem processes such as energy harvesting and light use efficiency. Our results show a persistent change in forest structural characteristics along the edges of forest fragments, which resulted in a significantly lower structural diversity, in comparison with the interior of the forest fragments. These structural changes could be observed up to 35 m from the forest edges and are likely to reflect even deeper impacts on other ecosystem variables such as microclimate and biodiversity. Traits related to vertical plant material allocation were more affected than traits related to canopy height. We demonstrate a divergent response from the forest understory (higher vegetation density close to the edge) and the upper canopy (lower vegetation density close to the edge), indicating that assessing forest disturbances using vertically integrated metrics, such as total plant area index, can lead to an erroneous interpretation of no change. Our results demonstrate the strong potential of terrestrial laser scanning for benchmarking broader-scale (e.g. airborne and space-borne) remote sensing assessments of forest distur-bances, as well as to provide a more robust interpretation of biophysical changes detected at coarser resolutions.
  • Artaxo, Paulo; Hansson, Hans-Christen; Andreae, Meinrat O.; Bäck, Jaana; Alves, Eliane Gomes; Barbosa, Henrique M. J.; Bender, Frida; Bourtsoukidis, Efstratios; Carbone, Samara; Chi, Jinshu; Decesari, Stefano; Despres, Viviane R.; Ditas, Florian; Ezhova, Ekaterina; Fuzzi, Sandro; Hasselquist, Niles J.; Heintzenberg, Jost; Holanda, Bruna A.; Guenther, Alex; Hakola, Hannele; Heikkinen, Liine; Kerminen, Veli-Matti; Kontkanen, Jenni; Krejci, Radovan; Kulmala, Markku; Lavric, Jost; de Leeuw, Gerrit; Lehtipalo, Katrianne; Machado, Luiz Augusto T.; McFiggans, Gordon; Franco, Marco Aurelio M.; Meller, Bruno Backes; Morais, Fernando G.; Mohr, Claudia; Morgan, William; Nilsson, Mats B.; Peichl, Matthias; Petäjä, Tuukka; Prass, Maria; Poehlker, Christopher; Poehlker, Mira L.; Poeschl, Ulrich; Von Randow, Celso; Riipinen, Ilona; Rinne, Janne; Rizzo, Luciana; Rosenfeld, Daniel; Silva Dias, Maria A. F.; Sogacheva, Larisa; Stier, Philip; Swietlicki, Erik; Soergel, Matthias; Tunved, Peter; Virkkula, Aki; Wang, Jian; Weber, Bettina; Maria Yanez-Serrano, Ana; Zieger, Paul; Mikhailov, Eugene; Smith, James N.; Kesselmeier, Juergen (2022)
    This review presents how the boreal and the tropical forests affect the atmosphere, its chemical composition, its function, and further how that affects the climate and, in return, the ecosystems through feedback processes. Observations from key tower sites standing out due to their long-term comprehensive observations: The Amazon Tall Tower Observatory in Central Amazonia, the Zotino Tall Tower Observatory in Siberia, and the Station to Measure Ecosystem-Atmosphere Relations at Hyytiala in Finland. The review is complemented by short-term observations from networks and large experiments. The review discusses atmospheric chemistry observations, aerosol formation and processing, physiochemical aerosol, and cloud condensation nuclei properties and finds surprising similarities and important differences in the two ecosystems. The aerosol concentrations and chemistry are similar, particularly concerning the main chemical components, both dominated by an organic fraction, while the boreal ecosystem has generally higher concentrations of inorganics, due to higher influence of long-range transported air pollution. The emissions of biogenic volatile organic compounds are dominated by isoprene and monoterpene in the tropical and boreal regions, respectively, being the main precursors of the organic aerosol fraction. Observations and modeling studies show that climate change and deforestation affect the ecosystems such that the carbon and hydrological cycles in Amazonia are changing to carbon neutrality and affect precipitation downwind. In Africa, the tropical forests are so far maintaining their carbon sink. It is urgent to better understand the interaction between these major ecosystems, the atmosphere, and climate, which calls for more observation sites, providing long-term data on water, carbon, and other biogeochemical cycles. This is essential in finding a sustainable balance between forest preservation and reforestation versus a potential increase in food production and biofuels, which are critical in maintaining ecosystem services and global climate stability. Reducing global warming and deforestation is vital for tropical forests.