Litter mass loss rates in pine forests of Europe and Eastern United States: some relationships with climate and litter quality |
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Authors: | B Berg M P Berg P Bottner E Box A Breymeyer R Ca de Anta M Couteaux A Escudero A Gallardo W Kratz M Madeira E Mälkönen C McClaugherty V Meentemeyer F Muñoz P Piussi J Remacle A Vi de Santo |
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Institution: | 1. Dept. of Forest Soils, Swedish University of Agricultural Sciences, P.O. Box 7001, S-750 07, Uppsala, Sweden 2. Dept. of Ecology and Exotoxicology, Free University of Amsterdam, P.O. Box 7161, MC-1007, Amsterdam, The Netherlands 3. CNRS, Route de Mende, BP 5051, F-34033, Montpellier Cedex, France 10. Dept. of Geography, Univ. of Georgia, Athens, GA, 30602, USA 4. Inst. of Geography and Spatial Organization, Polish Academy of Sciences, Krakowskie Prezedmiescie 30, PL-00-927, Warsaw, Poland 5. Fac. de Biologia, Univ. de Santiago, Santiago de Compostela, Spain 7. Fac. de Biologia, Dept. de Ecologia, Univ. de Salamanca, E-37008, Salamanca, Spain 6. Dept. of Ecology, Univ. of Seville, Apt 1095, E-41080, Seville, Spain 8. Internat. BAHC Core Project Office, BAHC Secretariate, Dietrich-Sch?fer-Weg 6-10, D-1000, Berlin 41, Federal Republic of Germany 9. Departemento de Ciencias do Ambiente, Inst. Superior de Agronomia, Tapada da Ajuda, 1399, Lisboa Codex, Portugal 15. Dept. of Forest Ecology, Finnish Forest Research Institute, P.O. Box 18, SF 01301, Vantaa, Finland 13. Dept. of Biology, Mount Union College, Alliance, OH, 44601, USA 11. Univ. degli Studi di Firenze, Istituto di Selvicoltura, Via S. Bonaventura 13, I-50145, Firenze, Italy 12. Dept. of Botany, Univ. of Liege, Sart Tilman, B-4000, Liege, Belgium 14. Dipartimento Biologia Vegetale, Univ. di Napoli, Via Foria 223, I-80139, Napoli, Italy
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Abstract: | The purpose of this study was to relate regional variation in litter mass-loss rates (first year) in pine forests to climate
across a large, continental-scale area. The variation in mass-loss rate was analyzed using 39 experimental sites spanning
climatic regions from the subarctic to subtropical and Mediterranean: the latitudinal gradient ranged from 31 °N to 70 °N
and may represent the the largest geographical area that has ever been sampled and observed for the purpose of studying biogeochemical
processes. Because of unified site design and uniform laboratory procedures, data from all sites were directly comparable
and permitted a determination of the relative influence of climateversus substrate quality viewed from the perspective of broad regional scales.
Simple correlation applied to the entire data set indicated that annual actual evapotranspiration (AET) should be the leading
climatic constraint on mass-loss rates (Radj
2 = 0.496). The combination of AET, average July temp. and average annual temp. could explain about 70% of the sites' variability
on litter mass-loss. In an analysis of 23 Scots pine sites north of the Alps and Carpatians AET alone could account for about
65% of the variation and the addition of a substrate-quality variable was sufficiently significant to be used in a model.
The influence of litter quality was introduced into a model, using data from 11 sites at which litter of different quality
had been incubated. These sites are found in Germany, the Netherlands, Sweden and Finland. At any one site most ( ≫ 90%) of
the variation in mass-loss rates could be explained by one of the litter-quality variables giving concentration of nitrogen,
phosphorus or water solubles. However, even when these models included nitrogen or phosphorus even small changes in potential
evapotranspiration resulted in large changes in early-phase decay rates.
Further regional subdivision of the data set, resulted in a range of strength in the relationship between loss rate and climatic
variables, from very weak in Central Europe to strong for the Scandinavian and Atlantic coast sites (Radj
2 = 0.912; AETversus litter mass loss). Much of the variation in observed loss rates could be related to continentalversus marine/Atlantic influences. Inland locations had mass-loss rates lower than should be expected on the basis of for example
AET alone. Attempts to include seasonality variables were not successful. It is clear that either unknown errors and biases,
or, unknown variables are causing these regional differences in response to climatic variables. Nevertheless these results
show the powerful influence of climate as a control of the broad-scale geography of mass-loss rates and substrate quality
at the stand level.
Some of these relationships between mass-loss rate and climatic variables are among the highest ever reported, probably because
of the care taken to select uniform sites and experimental methods. This suggest that superior, base line maps of predicted
mass-loss rates could be produced using climatic data. These models should be useful to predict the changing equilibrium litter
dynamics resulting from climatic change. |
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Keywords: | decomposition litter mass loss climate climate change pine actual evapotranspiration |
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