Increasing Atmospheric Carbon Dioxide: Tree Ring Evidence for Growth Enhancement in Natural Vegetation

Abstract

A response of plant growth to increased atmospheric carbon dioxide, which has been anticipated from laboratory data, may now have been detected in the annual rings of subalpine conifers growing in the western United States. Experimental evidence shows that carbon dioxide can be an important limiting factor in the growth of plants in this high-altitude environment. The greatly increased tree growth rates observed since the mid-l9th century exceed those expected from climatic trends but are consistent in magnitude with global trends in carbon dioxide, especially in recent decades. If correctly interpreted, these findings have important implications for climate studies involving tree ring observations and for models of the global carbon dioxide budget.

Has global change induced divergent trends in radial growth of Pinus sylvestris and Pinus halepensis at their bioclimatic limit? The example of the Sainte-Baume forest (south-east France)

“…Many studies attribute positive trends in radial increment to fertilisation by atmospheric CO 2 enrichment (Graybill and Idso, 1993;Kienast and Luxmoore, 1988;LaMarche et al, 1984;Rathgeber et al, 2000). Experimental studies with enhanced CO 2 -concentration on tree seedlings and saplings report stem growth stimulation in the first years of the experiment followed by stabilised growth in the next years (Dobbertin, 2005;Kilpeläinen et al, 2003).…”

Short-term variations and long-term changes in oak productivity in northeastern France. The role of climate and atmospheric CO 2

“…This has been observed in boreal forests in Europe (Hari et al, 1984) and North America (Payette et al, 1985; d 'Arrigo et al, 1987;Jozsa and Powell 1987), and also in the mountain forests of the temperate zones in Europe (Becker, 1989;Briffa, 1992) and North America (Lamarche et al, 1984;Graumlich et al, 1989;Peterson et al, 1990). Fewer studies have been carried out in the plain forests of temperate zones (Wagener et al, 1983).…”

A forward modeling approach to paleoclimatic interpretation of tree‐ring data

“…In both situations, statistical relationships, which may represent linearizations of nonlinear processes (see section 2), are difficult to validate for long period processes and for times outside the instrumental era and may not hold for paleoclimate or climate change experiments. For example, the application of statistical calibrations to an independent time period with a fundamentally different climatic regime, for example, with comparable temperatures but a general shift in water balance, may consequently lead to an erroneous climate reconstruction [LaMarche et al, 1984;Graybill and Idso, 1993;Briffa et al, 1998;Vaganov et al, 1999;Barber et al, 2000;Kirdyanov et al, 2003;Anchukaitis et al, 2006]. Hence the nature of trees as a biological archive of environmental conditions raises questions about the validity of linear, statistical approaches to interpretation of the data.…”