The Norwegian monitoring program for sub-alpine birch-forests Effects of air pollution and climate change on ground vegetation Vegar Bakkestuen & Per Arild Aarrestad
Norwegian sub-alpine birch-forests the forest line Content:: Presentation of the monitoring program Climatic and air pollution scenario in Norway Main drivers for vegetation change Monitoring approach Results Discussion
The Norwegian terrestrial monitoring program - TOV Time scale 1993-2016 7 (6) areas from south to north Effects of air pollution and climate change on sub-alpine birch forests TOV includes monitoring of: Ground vegetation Birds Rodents Epiphytic lichens Moths Radioactive deposition
Deviation from yearly mean temperature 1961-1990 ( C) Varmer climate in Norway Predicted 2,5 2,0 1,5 1,0 0,5 0,0-0,5-1,0-1,5-2,0 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 2100 TOV-period
Yearly precipitation in % of the normal 1961-1990 Wetter climate in Norway 140 130 120 Predicted 110 100 2100 90 80 70 60 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 TOV-period
Small decrease in total N-deposition Lund et al. (2013)
mg N/m 2 /year Total nitrogen deposition in TOV-areas 1800 1600 Total nitrogen deposition 1400 1200 1000 800 600 400 200 Lund Møsvatn Gutulia Åmotsdalen Børgefjell Dividalen CL of N South North 0 1978-1982 1992-1996 1997-2001 2002-2006 2007-2011 Climate periods
Strong decrease in S-deposition Lund et al. (2013)
mg S/m 2 *year Change in S-deposition in TOV-areas Decreased deposition 1600 1400 1200 1000 800 600 400 200 0 Total S deposition 1978-1982 1992-1996 1997-2001 2002-2006 2007-2011 Lund Dividalen Aas et al. (2012)
Ground vegetation Dwarf shrubs Herbs Graminoids Bryophytes Lichens
Main drivers for vegetation change Climate Temperature Precipitation Soil Nutrients ph Air pollution N-deposition S-deposition Ground vegetation Dwarf shrubs Herbs Graminoids Bryophytes Lichens Grazing Domestic animals Deers Rodents Moths Natural forest development
Monitoring approach - ground vegetation 10 macro-plots (5 x 10 m), covering the main environmental gradients, with 5 permanently marked 1m 2 vegetation plots, totally 50 permanet vegetation plots Species abundances measured by both subplot frequency (16 subplots) and percentage cover Soil characteristics sampled and analysed for soil ph, soil extractable cations, S and N Analysed each five years Ca. 120.000 recordings of species occurrence from 1993 to 2015 Bakkestuen et al. (2010)
Analyses of permanent plots in Børgefjell National Park Year 2005 Year 2015
% cover Results - all TOV localities: Changes of herbs from 1993-2015 Increased cover of herbs 60 Average cover of herbs 50 40 30 20 10 Lund Møsvatn Gutulia Åmotsdal Børgefjell Dividal 0 1993-1997 1998-2002 2003-2007 2008-2012 2013-2017 Analyse period
% cover Changes of grasses from 1993-2015 Increased cover of graminoids 30 Average cover of graminoids 25 20 15 Lund Møsvatn Gutulia 10 5 Åmotsdal Børgefjell Dividal Avenella flexuosa 0 1993-1997 1998-2002 2003-2007 2008-2012 2013-2017 Analyse period
% cover Changes of liverworts from 1993-2015 Decreased cover of liverworts 20 18 16 Liverworts 14 12 10 8 6 4 2 0 1993-1997 1998-2002 2003-2007 2008-2012 2013-2017 Analyse period Lund Møsvatn Gutulia Åmotsdal Børgefjell Dividal Bazzania trilobata
Frequancy abundance Changes of lichens from 1993-2015 Decreased cover of lichens 14 Lichens 12 10 8 Møsvatn 6 Gutulia Åmotsdal 4 Børgefjell 2 0 1993-1997 1998-2002 2003-2007 2008-2012 2013-2017 Dividal Cladonia stellaris Analyse period
ph Changes in soil ph from 1993-2015 Increased ph in all TOV-areas 5,0 Soil ph - all TOV-areas 4,8 4,6 4,4 4,2 4,0 Lund Møsvatn Gutulia Åmotsdal Børgefjell Dividal 3,8 1993-1997 1998-2002 2008-2012 2013-2017 Analyse periods
Changes in soil nutrients 1993-2015 More nutrient-rich soil Increased Ca, Mg, K Increased cation exchange capacity Increased base saturation Increased total N
Vegetation response to warmer, wetter and longer growth season Field layer Increased temperature leads to more available nutrients Increased cover of competative species Increased growth of herbs and grasses Increased cover of field layer
Vegetation response to warmer, wetter and longer growth season Bottom layer bryophytes and lichens Increased growth of large mosses in southern areas 6 Average cover of 50 plots Lund area, southern Norway % 5 4 3 2 P < 0.004 Hylocomium splendens Sphagnum quinquefarium 1 P < 0.007 0 1996 2001 2006 2011
Vegetation response to warmer, wetter and longer growth season Increased cover of field layer (herbs and grasses) Less light to the ground Increased competition for light Decreased abundance of non-competative species Decreased abundance of liverworts and lichens
AVERAGE COVER % Vegetation response to Nitrogen Increased abundance of grasses 10 8 Molinia caerulea (average cover of 50 plots) Lund area southern Norway P < 0.0001 6 4 2 0 1996 2001 2006 2011 Decreased abundance of lichens Absent in the southernmost area Lund
Vegetation response to less acid rain Increased accessibility of soil nutrients Increased plant diversity Increase in nutrient demanding species
Summary Climate change: Warmer and wetter climate Reduced acid rain Minor changes in N-deposition Increased temperature and precipitation leads to a more productive field layer, consisting of herbs and graminoids Competition for light reduce the abundance of liverworts and lichens Decreased sulphur deposition has lead to less acidification and more nutrient-rich soils High nitrogen deposition has over time increased the abundance of grasses in southern Norway
Conclusions The TOV-monitoring approach shows fast responses in vegetation, caused by broad scale environmental impacts The forest ground vegetation contains a large set of sensitive indicators of environmental change The monitoring concept also allows for using vegetation response for early detection of small changes in the environment A great dataset for predicting future changes in vegetation and the environment
Thank you for your attention! The Norwegian sub-alpine birch-forests in future?