Báo cáo lâm nghiệp: "Response of shoot growth and gas exchange of Picea abies clones to rain acidity and the addition of ions"

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Response of shoot growth and gas exchange of Picea abies clones to rain acidity and the addition of ions P. Van Elsacker I. Impens Department of Biology, University of Antwerp (UIA), Universiteitsplein 1, B-26 10 Wifrijk-Antwerpen, Belgium Introduction without (-) and with (+) the ionic mixture men- tioned below; pH 4.0- and 4.0+: same as pH 5.6 but the solution was acidified to pH 4.0 with a (S02-/NO- mixture of sulfuric and nitric acids The novel forest decline observed in Eu- m mg/1 weight ratio 2.4). Ionic concentrations = 2 S04 rope and the U.S.A. may be caused by were: 4.50 2.00 NOg, 1.20 NH4, several factors, among them, air pollution K+, 0.60 Ca +, 2 0.99 Na+, 1.45 CI-, 0.30 is thought to be very important. Interfer- 0.30 Mg and 0.40 HS0 (Van Elsacker era/., + 2 3 ence of pollutants with the ecophysiologi- 1988). cal performance of forest trees needs to Gas measured fully grown exchange was on current year shoots during the summer. C0 2 be investigated in order to understand the exchange rate (CER) was measured at PPFD actual working mechanisms. The aim of saturation with a portable, closed-loop system this study was to examine the effect of aci- (Van Elsacker and Impens, 1986). The number dic wet deposition on C0 exchange, 2 of data was 12 measurements x 4 treatments x needle conductance and shoot growth of 4 (parts of) days. Needle conductance (Gn) was measured with an automatic diffusion porome- Norway spruce, particularly the effect of ter developed at the laboratory (procedure com- acidity and the addition of a realistic ionic parable to Delta-T porometer). Data were calcu- mixture to simulated acidic precipitation. lated on a needle dry weight basis (gdw- The ). 1 number of Gn data was 13 measurements x 4 treatments x 3 (parts of) days for clone 1011, and 11 x 4 x 4, respectively, for the other clones. To analyze the gas exchange data, a 3- Materials and Methods way analysis of variance with the factors pH, ions (- or +) and day was used; the factor ’day’ allowed for temporal, environmental and eco- Four year old potted plants of 3 Belgian Picea physiological variations. abies (L.) Karst. clones were grown in a green- house (clone number 1007, 1011 and 1019). The length of top and lateral current year The plants were sprayed 3 times a week shoots of 13 plants per treatment and per clone throughout the growing season with a hand was measured every 3-4 d from bud break (mid- pumped sprayer. The 4 treatments were: May) until growth had stopped (July, total of 13 pH 5.6- and 5.6+: de-ionized water in equili- measurement d). A non-linear regression proce- brium with the atmospheric C0 pressure, resp. 2 dure was used to fit a logistic growth function.
Results 4.0 and a significant interaction of pH x + ions. The Newman-Keuls test yielded the following: 4.0+ 5 5,6+ 4.0-. 6- - Treatment means, pooled for the whole The conductance of clone 1019 was summer, of net C0 exchange (CER) and 2 also reduced at pH 4.0 and a significant + needle conductance (Gn) of the 3 clones interaction of pH x ions x d was found. are shown in Fig. 1 a, b. C0 exchange 2 The Newman--Keuls test was not signifi- rate was reduced for all clones at pH 4.0+ cant at P 0.72) but there from low to high, underlined treatments were no differences of the parameter esti- are not significantly different at P
and the addition of the ionic mix- the curves in Fig. 2a. Relative growth acidity ture. The effect of acidic rain on the Gn of rates (RGR) are plotted in Fig. 2b. The clone 1019 seemed to depend upon envi- lines connecting the RGR values for differ- ronmental and/or ecophysiological condi- ent time periods of each pH treatment tions (interaction pH x ions x d). A reduc- cross one another, there were no clear dif- tion of the photosynthetic capacity may ferences between the 4 treatments. Simi- have consequences for growth and pro- lar results (not shown here) were obtained duction of forest trees, as observed for for top shoot growth of clones 1011 and poplar (Van Elsacker et al., 1988). How- 1019, the latter showing lower final ever, length growth of top (and lateral) lengths (A 112-136 mm), lower b-values = shoots in this experiment was not obvious- (b 4.8-5.7) and inflexion points on d = ly changed by any simulated (acidic) pre- 35-38. The growth of lateral shoots also did not show clear differences between cipitation treatment. the pH treatments. Acknowledgments Discussion and Conclusion This work is supported by the Commission of the European Communities, project no. EV4V- The reduction of CER and Gn at pH 4.0+ 0017-B (GDF). The authors wish to thank Dr. A. and the significant pH x ions interaction Nanson (Forestry Experimental Station, Groe- suggest a synergism between increasing nendaal-Hoeilaart) for the clones.
the European Communities. Workshop Pro- References ceedings, Lokeberg, 19-23 October 1986, pp. 122-131 Van Elsacker P., Martens C. & Impens 1. (1988) Van Elsacker P. & Impens 1. (1986) Direct Direct effects of acid wet deposition on photo- effects of simulated acid wet deposition on gas synthesis, stomatal conductance and growth of exchange of Norway spruce. In: Direct Effects Populus cv. Beziupr6. In: Air Pollution and Eco- of Dry and Wet Deposition on Forest Ecosys- systems. (Mathy P., ed.). D. Reidel Publishing tems - in Particular Canopy Interactions. Air Company, Dordrecht, Holland, pp. 728-733 Pollution Research Report 4. Commission of