Resistance of chestnut (Castanea sativa Mill.) to SO
2in comparison with other tree species
Valentin Bolea and DànutChira
Forest Research and Management Institute, ICAS, Section of Brasov, Closca 13, 2200 Brasov, Romania bolea@rdsbv.ro, chira@rdsbv.ro
Abstract
Sweet chestnut had better resistance to sulphur pollution than other forest species as measured by the adaptability indices (seedling survival and tree increment). Dendrometric parameters showed that chestnut had the best results in the experimental plantation situated on moderate soil texture. In the plantation settled on clay soil, its growth was moderate.
In 1999, the sulphur content of the leaves was high in both plantations for all the forest species, varying from 1329 ppm (Prunus serotina) to 7166 ppm (Betula pendula). The ratios between sulphur and nitrogen, phosphorus, potassium, and calcium, were unbalanced forQuercus rubra, Castanea sativa, Populus tremula, and Robinia pseudacacia. In older natural stands situated in regions without local pollution, the leaf sulphur content was significantly lower (<780 ppm for Fagus sylvatica and Quercus petraea).
The N/S ratio in chestnut leaves was significantly under the Zech toxicity level.The N/S ratio of chestnut was not significantly different from the N/S ratio of the pioneer species (aspen and birch), suggesting a comparable resistance to sulphur.
Keywords: pollution, forest, leaf analyses, N/S ratio, relative resistance
1 Introduction
The region surrounding the city of Baia Mare in the north-western part of Romania has serious pollution problems owing to the mining and processing of non-ferrous metals. The amount of sulphur oxides emitted by Baia Mare city industry increased over time, reaching a maximum of 52 094 t/yr in 1982. According to the data of Baia Mare Environment Protection Agency, sulphur dioxide concentration in the air varied in the 1990s from 17.35 µm/m3(in 1999) to 263.92 µm/m3 (in 1994). In 1999, the lead concentration in Baia Mare exceeded by a factor of 9 the standards (NÀDIHANet al. 2001).
As a consequence, local pollution (lead, sulphur, zinc, arsenic, cadmium, copper, cyanide) has affected for a long period both agriculture and forest ecosystems. The most important pollutants – lead and sulphur – have a strong influence on plant morphology and physiology.
Leaf and sprout distortion or necrosis, crown thinning, branch and tree dying are some of the more common symptoms in the polluted forests (BOLEA1984, 1999).
Several studies have revealed serious losses in forest growth due to local pollution. The radial increment was reduced by 4% to 43% according to the distance from the source of pollution, which mainly involves sulphur oxides (IANCULESCU1977; DINCÀ1999). 12 000 ha of polluted forest have been recorded and it is estimated that 10% of the surface area of the county is polluted by metals and sulphur (NÀDIHANet al. 2001).
Ecological and biometrical parameters are generally used to indicate the adaptability, productivity and resistance of forest species. In polluted sites, seedling survival capacity has been found to be negatively correlated with a decrease in humus and a degradation in the soil structure (CHIRITÀet al. 1974). Sulphur pollution results in soil acidification (SAVUand BOLEA1977), diminishes the availability of soil nutrients (BOLEA1999), and decreases the soil productivity (GEAMBAHU1997). Leaf necrosis appears to be linked to the susceptibility of a forest species to SO2pollution (VANHAUTand STRATMANN1970). Biometrical charac-
teristics (tree height, diameter, andradial increment) seem to correlate strongly with resist- ance to SO2(and other pollutants; IANCULESCU1977). SO2obstructs the opening mechanism of the stomata and decreases the photosynthetic activity (SAVUand BOLEA1977).
In Romania the most important natural stands of chestnut (Castanea sativa)are found in the Baia Mare region. There chestnut occupies the northeast of the European natural range (SOÓ1970) and is well adapted to the acidic soils.
Field observations suggest that chestnut may show higher resistance to sulphur dioxide pollution than other tree species. Two experimental plantations with chestnut and other forest trees in two heavily polluted stands near Baia Mare were studied to test this hypothesis.
2 Method
Relative resistance in polluted sites
Two experimental plantations, “Vicleana Valley” and “Limpedea”, were established in 1974 in areas in Baia Mare polluted with SO2, lead and other secondary pollutants (SAVUand BOLEA 1977). The first site has acidic soil (pH: 3.8–4.0) with 37–47% clay and 11–12% base saturation (V%). The second site has acidic soil (pH: 3.6–4.0 in the first 50 cm) with 23–24% clay and 19–47% base saturation (V%). Ten species: Betula pendula, Castanea sativa, Chamaecyparis lawsoniana,Larix decidua, Quercus rubra, Quercus petraea, Prunus serotina, Populus tremula, Pinus nigra, andRobinia pseudacacia were planted in randomised blocks (nine forest species/test site, 100 trees/species, and six repetitions). Fagus sylvatica (one of the most important local species) was considered too sensitive for these particular sites.
Seedling survivalwas assessed in the autumns of 1974 and 1975. Leaf injury (necrosis and discoloration) was estimated in 1974 by inspecting 100 leaves from the superior part of the crown from 10 trees per species. Tree height, diameterand radial increment of 10 trees per species were measured in 1994. These six characteristics were used to calculate the relative resistance of a species (adaptability). For each forest species, the indices of relative resistance were calculated for each variable (Ir = 10x/M; where ‘x’ is the result for the species and ‘M’ is the best result for this variable for all species). The global index of relative resistance of a species is the average of all indices.
Leaf analyses
In 1999, the concentration of 11 elements (S, N, P, K, Ca, Mg, Mn, Fe, Cu, Zn, and Na) was meas- ured in the leaves according to the European standard method (UN/ECE-CEC 1994).
Comparative information was taken from several older stands, both affected and unaffected by local pollution, from the European Forest Monitoring Network for Fagus sylvatica, Quercus petraea, and Q. robur. Variance analyses and Duncan tests were used for statistical interpretation.
3 Results
Relative resistance to pollution
The best relative resistance was noticed for Castanea sativawith a global index of 8.5 in the
“Vicleana Valley” and 9.1 in ”Limpedea” and for Quercus rubra with 8.6 and 8.7, respectively (Table 1).
Taking only the dendrometric indices into account, the chestnut tree characteristics were different at the two sites (Table 1).
– In the plantation “Limpedea”, with a low clay concentration, chestnut recorded the best results of all species (global index of 9.1).
– In the plantation “Vicleana Valley”, with a high clay concentration, chestnut had only moderate growth (diameter index of 8.2, height index of 6.8, and global index of 7.9).
Seedlings of all species showed leaf damage. Discoloration and necrosis were lowest in Pinus nigra and Chamaecyparis lawsoniana.
Table 1. Relative resistance to local pollution in two experimental plantations. Tree species BP Betula pendula;CS Castanea sativa;CL Chamaecyparis lawsoniana;LD Larix decidua;QP Quercus petraea;
QR Q. robur;PS Prunus serotina;PT Populus tremula;PN Pinus nigra;RP Robinia pseudacacia;Exp experimental plantations: VV = “Vicleana Valley” and L = “Limpedea” plantations; Par parameters: S1, S2: survival after 1 and 2 years, respectively; Ld: leaf damage; H: height; D: diameter; RI radial in - crement; Val values; Ir1-6relative resistance indices; Irg global index of relative resistance; Av average.
Par Val Exp MU Tree species
Ir CS QP QR RP PT BP PS PN CL LD
S1 Val VV % 91.9 81.9 84.2 35.0 80.4 59.0 74.1 84.1 – 70.1
Ir1 VV 10.0 8.9 9.2 3.8 8.8 6.4 8.1 9.2 – 7.6
Val L % 90.8 91.1 93.0 83.9 51.3 51.1 97.6 – 58.4 86.7
Ir1 L 9.3 9.3 9.5 8.6 5.3 5.2 10.0 – 6.0 8.9
S2 Val VV % 90.9 65.4 66.2 35.0 64.5 48.3 58.6 84.1 – 21.4
Ir2 VV 9.6 7.8 7.9 4.2 7.7 5.7 7.0 10.0 – 2.5
Val L % 81.0 71.0 68.4 42.7 22.8 37.5 84.6 – 37.1 42.2
Ir2 L 9.6 8.4 7.4 5.1 2.7 4.4 10.0 – 4.4 5.0
Ld Val VV % 51.3 52.3 52.4 46.2 57.6 59.1 53.3 64.7 – 44.9
Ir3 VV 7.9 8.1 8.1 7.1 8.9 9.1 8.2 10.0 – 6.9
Val L % 55.0 62.8 61.8 55.8 56.3 56.6 60.3 – 64.8 49.2
Ir3 L 8.5 9.7 9.5 8.6 8.7 8.7 9.3 – 10.0 7.6
D Val VV cm 11.8 13.1 12.9 13.8 10.4 13.0 9.6 – – 14.4
Ir4 VV 8.2 7.3 9.3 9.5 7.2 9.0 6.6 – – 10.0
Val L cm 14.3 7.3 13.5 11.8 11.3 11.3 12.5 – 13.3 11.0
Ir4 L 10.0 5.1 9.1 8.2 7.9 7.9 8.7 – 9.3 7.7
H Val VV m 8.1 7.4 9.9 11.1 9.6 11.9 6.9 – – 8.9
Ir5 VV 6.8 6.2 8.3 9.3 8.1. 10.0 5.8 – – 7.5
Val L m 14.3 7.3 13.5 11.8 11.3 11.0 12.5 – 13.3 11.0
Ir5 L 10.0 5.1 9.1 8.2 7.9 7.8 8.7 – 9.3 7.7
RI Val VV mm 3.8 3.1 4.0 4.6 3.1 2.9 2.2 – – 3.5
Ir6 VV 8.3 6.7 8.7 10.0 6.7 6.4 4.9 – – 7.7
Val L mm 3.4 3.4 3.4 3.4 2.5 3.9 2.0 – 2.7 4.7
Ir6 L 7.2 7.2 7.2 7.2 5.5 7.7 4.3 – 5.7 10.0
Av Irg VV 8.5 7.8 8.6 7.4 7.9 7.8 6.9 – – 7.0
Irg L 9.1 7.9 8.7 7.7 6.5 7.8 8.6 – 7.5 7.9
Sulphur content of the leaves
The sulphur content of the leaves varied among the species (Table 2). The highest concen- trations were recorded in Betula pendula(6210 ppm in “Vicleana Valley” and 7166 ppm in
“Limpedea”) and Populus tremula(4731 and 5316 ppm). Castanea sativaleaves showed only 2043 and 2285 ppm. Only in the leaves of Prunus serotinawere the sulphur concentrations (1329 ppm and 1363 ppm) near the critical level of 1300–1500 ppm (BONNEAU1995).
The different tree species showed also significant differences in the proportions of sulphur and nitrogen, phosphorus, potassium, and calcium (Table 2).
In comparison with Quercus petraea and Fagus sylvatica from non-polluted stands, only Betula pendula, Quercus petraea, and Prunus serotina showed no significant differences con- cerning the ratio of S/N, S/P, S/K, and S/Ca. Therefore, the critical toxicity level of sulphur concentration in leaves seems to be higher for these species (Table 2).
In contrast, the ratio between the sulphur concentration in the leaves and the concen - tration in the other elements was generally unbalanced in Populus tremula,Quercus rubra, Robinia pseudacacia, and Castanea sativa (Table 2). For example, the N/S rapport was critical (<8 according to ZECH et al. 1985) for Q. rubra (2.0–3.6), C. sativa (2.7–3.7), P. tremula (3.0–6.5), and R. pseudacacia (4.8).
Table 2. Tree species leaf content from the experimental plantation and control stands. Sp species; CS Castanea sativa;BP Betula pendula; FS Fagus sylvatica; QP Q. petraea;QR Quercus robur; QRR Quercus rubra;PS Prunus serotina;PT Populus tremula;RP Robinia pseudacacia;c control: older stands from polluted (p) or not polluted (n) areas; S, N/S, P/S, K/S, Ca/S, Mg/S (chemical elements); “/”
separates values from the “Vicleana Valley” and ”Limpedea” plantations.
Sp S (ppm) N/S P/S K/S Ca/S Mg/S
CS 2284.5 / 2043.3 4.62 / 8.75 0.84 / 0.82 4.46 / 5.23 4.75 / 3.73 1.04 / 1.12 BP 6210.3 / 7166.0 2.77 / 3.09 0.37 / 0.28 1.77 / 1.67 2.08 / 1.58 0.50 / 0.35 PS 1329.4 / 1362.7 14.54 / 10.40 2.13 / 2.03 8.78 / 8.27 15.01 / 9.48 2.54 / 2.22 PT 4731.3 / 5316.7 2.47 / 2.27 0.40 / 0.25 1.93 / 1.20 4.25 / 4.37 0.36 / 0.61 QP 3011.8 / – 3.52 / – 1.03 / – 4.06 / – 4.76 / – 0.49 / – QRR 3432.3 / 3258.7 4.17 / 4.83 0.54 / 0.52 3.04 / 2.93 3.13 / 3.28 0.29 / 0.56 RP 2944.3 / – 7.24 / – 0.50 / – 2.13 / – 7.59 / – 0.41 / –
QRcp 1307.5 15.91 1.27 6.43 6.39 1.03
FScp 973.9 22.67 1.48 8.39 11.36 1.37 QPcn 730.5 19.36 2.89 9.34 14.53 2.00 QPcn 714.0 26,26 2.37 11.62 14.74 3.74
FScn 776.5 24.69 2.61 6.70 8.89 1.74
FScn 605.8 34.49 2.78 10.96 20.97 2.43
4 Discussion
Relative resistance to pollution
According to the global index, sweet chestnut showed the best results at the polluted sites among 10 broadleaved species due to the following characteristics:
– It adapts well to acidic soils, where seedling survival was found to be very good in the first year. The pivotal root system developed in the first year allowed rapid passage through the most polluted layer of the soil and supported good seedling survival in the second year (index of 9.6 in both plantations).
– It showed vigorous diameter and height growth in the first 20 years (maximum index 10 in both plantation). Therefore, chestnut seems to grow well and be resistant in polluted stands, even on very acidic and poor soils provided they do not have a strong (clay) texture.
The sensitivity of chestnut leaves (indicated by the necroses) to SO2was relatively high, but all the tested species seem to have low sensitivity.
Leaf sulphur content
The capacity of chestnut leaves to metabolise the sulphur was significant higher in chestnut (2.4 and 1.9 times higher), than in the local species Fagus sylvatica and Quercus robur (control from polluted or unpolluted natural stands). Thus, chestnut seems to recycle the atmospheric sulphur with more success than the most important local species and partially protects the soil from acidic precipitation (by crown retention). Pioneer species (especially Betula pendulaand Populus tremula) metabolised the largest amount of sulphur. Therefore, they should be encouraged in highly polluted areas.
The amount of sulphur in chestnut leaves in both plantations exceeded the critical toxicity level (1300–1500 ppm – AUCLAIR1976; BONNEAU1988) and also the higher toxicity level for beech (2000 ppm – STEFANet al.1997).
The medium N/S ratio in chestnut leaves was 4.6 and thus significantly below the toxicity level of 8 (ZECHet al. 1985). No die-back symptoms were found, indicating a good resistance to sulphur oxides. The N/S ratio of chestnut was not significantly different than the N/S ratio of the pioneer species, aspen and birch, suggesting a comparable resistance to sulphur oxides.
In old forest stands in the area around Baia Mare city, Q. robur fixed 1308 ppm sulphur and F. sylvatica 974 ppm. In contrast, these species accumulated only between 606 and 777 ppm of sulphur in their leaves if grown in Romanian regions without significant local pol - lution.
5 References
AUCLAIR, B., 1976: Effets du dioxyde de soufre sur les arbres et la forêt. Etude bibliographique, Ardon Station de recherches sur la Fôret et l’Environnement INRA Centre d’Orléans.
BOLEA, V., 1984: [Silvicultural study on chestnut in the northwestern part of Romania]. Ph.D.
thesis, University Transilvania Brasov (in Romanian).
BOLEA, V., 1999: [Mineral nutrition of the principal forest species from Romania]. University Transilvania of Brasov (in Romanian).
BONNEAU, M., 1988: La diagnostique foliare. Rev. for. fr. No special.
BONNEAU, M., 1995: Fertilisation des fôrets dans les pays tempérés. Nancy Cedex, ENGREF.
CHIRITÀ, C.D., 1974: [Ecopedology]. Bucharest, Ceres Publ. (in Romanian).
DEVRIES, W.; REINDS, G.J.; KERKVOORDE VAN, M.S.; HENDRIKS, C.M.A.; LEETERS, E.E.J.M.;
GROSS, C.P.; VOOGD, J.C.H.; VEL, E.M., 2000: Intensive Monitoring of Forest Ecosystems in Europe. Bruxelles, Geneva, EC-UN/ECE.
DINCÀ, L., 1999: [Auxological researches in forests affected by industrial pollution]. Scientific rapport. Bucharest, ICAS (in Romanian).
GEAMBAHU, N., 1997: [Research on forest soil quality on the level I and II of the monitoring network, in correlation with the health status of forest and some environmental factors].
Bucharest, ICAS Publ. (in Romanian).
IANCULESCU, M., 1977: [The influence of air pollution on forest increment]. Bucharest, Agricultural materials editorial office (in Romanian).
NÀDIHAN, I.; CHERECHEH, D.; IEREMIA, G., 2001: [Baia Mare pollution – Aurul case]. Vasile Goldis University Press (in Romanian).
SAVU, G.; BOLEA, V., 1977: [Forest ecosystem conservation in Baia Mare polluted zone].
Maramures Nature Protection (in Romanian).
SOÓ, R., 1970: [Hungarian flora and vegetation], Budapest (in Hungarian).
STEFAN, K.; FÜRST, A.; HACKER, R.; BARTELS, U., 1997: Forest Foliar Condition in Europe.
Results of large-scale foliar chemistry surveys (survey 1995 and data from previous years).
Brussels, Geneva, Vienna, EC-UN/ECE-FBVA. 207 pp.
UN/ECE-CEC, 1994: Manual on methods and criteria for harmonized sampling, assessment, monitoring and analysis of the effects of air pollution on forests. Hamburg, Prague, Programme Coordinating Centers.
VAN HAUT, H.; STRATMANN, H., 1970: Farbtafelatlas über Schwefeldioxid. Wirkungen an Pflanzen. Landesanstalt für Immissions- und Bodennutzungsschutz des Landes Nordrhein- Westfalen. Essen, W. Girardet.
ZECH, W.; SUTNER, T.; POPP, E., 1985: Elemental analyses and physiological responses of forest trees in SO2polluted areas of NE Bavaria. Water Air Soil Pollut. 25: 175–183.
Accepted 26.3.02
