Implications of albedo changes following afforestation on the benefits of forests as carbon sinks

Abstract. Increased carbon storage with afforestation leads to a decrease in atmospheric carbon dioxide concentration and thus decreases radiative forcing and cools the Earth. However, afforestation also changes the reflective properties of the surface vegetation from more reflective pasture to relatively less reflective forest cover. This increase in radiation absorption by the forest constitutes an increase in radiative forcing, with a warming effect. The net effect of decreased albedo and carbon storage on radiative forcing depends on the relative magnitude of these two opposing processes. We used data from an intensively studied site in New Zealand's Central North Island that has long-term, ground-based measurements of albedo over the full short-wave spectrum from a developing Pinus radiata forest. Data from this site were supplemented with satellite-derived albedo estimates from New Zealand pastures. The albedo of a well-established forest was measured as 13 % and pasture albedo as 20 %. We used these data to calculate the direct radiative forcing effect of changing albedo as the forest grew. We calculated the radiative forcing resulting from the removal of carbon from the atmosphere as a decrease in radiative forcing of −104 GJ tC−1 yr−1. We also showed that the observed change in albedo constituted a direct radiative forcing of 2759 GJ ha−1 yr−1. Thus, following afforestation, 26.5 tC ha−1 needs to be stored in a growing forest to balance the increase in radiative forcing resulting from the observed albedo change. Measurements of tree biomass and albedo were used to estimate the net change in radiative forcing as the newly planted forest grew. Albedo and carbon-storage effects were of similar magnitude for the first four to five years after tree planting, but as the stand grew older, the carbon storage effect increasingly dominated. Averaged over the whole length of the rotation, the changes in albedo negated the benefits from increased carbon storage by 17–24 %.

[1]  E. Tomppo.  National Forest Inventories : pathways for common reporting , 2010 .

[2]  Andrew E. Suyker,et al.  Albedo estimates for land surface models and support for a new paradigm based on foliage nitrogen concentration , 2010, Global Change Biology.

[3]  J. Leathwick,et al.  Climate Surfaces for New Zealand , 2002 .

[4]  P. Beets,et al.  Soil carbon protection in podocarp/hardwood forest, and effects of conversion to pasture and exotic pine forest. , 2002, Environmental pollution.

[5]  P. Beets,et al.  Description and validation of C_change: A model for simulating carbon content in managed Pinus radiata stands , 1999 .

[6]  Jehn-Yih Juang,et al.  Separating the effects of albedo from eco‐physiological changes on surface temperature along a successional chronosequence in the southeastern United States , 2007 .

[7]  M. Kirschbaum,et al.  Temporary Carbon Sequestration Cannot Prevent Climate Change , 2006 .

[8]  M. Kirschbaum,et al.  Can Trees Buy Time? An Assessment of the Role of Vegetation Sinks as Part of the Global Carbon Cycle , 2003 .

[9]  Jiaguo Qi,et al.  A Simple Physical Model of Vegetation Reflectance for Standardising Optical Satellite Imagery , 2001 .

[10]  John E. Walsh,et al.  Thermodynamic and Hydrological Impacts of Increasing Greenness in Northern High Latitudes , 2006 .

[11]  K. Trenberth,et al.  Earth's annual global mean energy budget , 1997 .

[12]  Elena Shevliakova,et al.  Modeled Impact of Anthropogenic Land Cover Change on Climate , 2007 .

[13]  Joanna D. Haigh,et al.  Radiative forcing of climate change , 2002 .

[14]  H. Gholz.  Applications of Physiological Ecology to Forest Management , 1997 .

[15]  R. Betts.  Offset of the potential carbon sink from boreal forestation by decreases in surface albedo , 2000, Nature.

[16]  J. Landsberg.  10 – Applications of Modern Technology and Ecophysiology to Forest Management , 1997 .

[17]  R. Betts,et al.  Changes in Atmospheric Constituents and in Radiative Forcing. Chapter 2 , 2007 .

[18]  Kees Klein Goldewijk,et al.  Biogeophysical effects of land use on climate : Model simulations of radiative forcing and large-scale temperature change , 2007 .

[19]  Gu Lb,et al.  Soil carbon stocks and land use change : a meta analysis , 2022 .

[20]  Corinne Le Quéré,et al.  An efficient and accurate representation of complex oceanic and biospheric models of anthropogenic carbon uptake , 1996 .

[21]  S. Liang.  Narrowband to broadband conversions of land surface albedo I Algorithms , 2001 .

[22]  M. Claussen,et al.  Past land use decisions have increased mitigation potential of reforestation , 2011 .

[23]  A. Rosenfeld,et al.  Global cooling: increasing world-wide urban albedos to offset CO2 , 2009 .

[24]  David Neil Bird,et al.  Integration of albedo effects caused by land use change into the climate balance: Should we still account in greenhouse gas units? , 2010, Forest Ecology and Management.

[25]  John E. Walsh,et al.  Relative impacts of vegetation coverage and leaf area index on climate change in a greener north , 2007 .

[26]  W. Landman.  Climate change 2007: the physical science basis , 2010 .

[27]  Pierre Friedlingstein,et al.  Impact of land cover change on surface climate: Relevance of the radiative forcing concept , 2007 .

[28]  Alan G. Barr,et al.  The effect of post-fire stand age on the boreal forest energy balance , 2006 .

[29]  Victor Brovkin,et al.  Modelling climate response to historical land cover change , 1999 .

[30]  J. Houghton,et al.  Climate change 2001 : the scientific basis , 2001 .

[31]  Alvaro Montenegro,et al.  The net carbon drawdown of small scale afforestation from satellite observations , 2009 .

[32]  Atul K. Jain,et al.  An introduction to simple climate models used in the IPCC second assessment report , 1997 .

[33]  P. Beets,et al.  ACCUMULATION AND PARTITIONING OF DRY MATTER IN PINUS RADIATA AS RELATED TO STAND AGE AND THINNING , 1987 .

[34]  Jiaguo Qi,et al.  Erratum to “A simple physical model of vegetation reflectance for standardising optical satellite imagery” [Remote Sens. Environ. 75(3) 350–359 , 2001 .

[35]  T. Phillips,et al.  Biogeophysical effects of CO2 fertilization on global climate , 2006 .

[36]  K. Caldeira,et al.  Combined climate and carbon-cycle effects of large-scale deforestation , 2006, Proceedings of the National Academy of Sciences.

[37]  P. Beets,et al.  WATER USE BY MANAGED STANDS OF PINUS RADIATA, INDIGENOUS PODOCARP/HARDWOOD FOREST, AND IMPROVED PASTURE IN THE CENTRAL NORTH ISLAND OF NEW ZEALAND , 2007 .

[38]  Lu Zhang,et al.  Response of mean annual evapotranspiration to vegetation changes at catchment scale , 2001 .

[39]  K. Eckhardt,et al.  Plant parameter values for models in temperate climates , 2003 .

[40]  K. G. McNaughton,et al.  Stomatal Control of Transpiration: Scaling Up from Leaf to Region , 1986 .

[41]  M. Kirschbaum,et al.  Observed and modelled soil carbon and nitrogen changes after planting a Pinus radiata stand onto former pasture , 2008 .

[42]  M. G. Messina,et al.  Will afforestation in temperate zones warm the earth , 2011 .