Abstract
This study was carried out to investigate the effect of forest soil acidification on the distribution of exchangeable cations($Ca^{2+}$, $Mg^{2+}$, $Al^{3+}$) and heavy metals(Cu, Zn, Mn, Pb, Cd) in soil, and to understand the relation of the soil chemical properties and the distribution of nutrients and hear metals in fine root and foliage. The results through survey on the long - term change of soil pH and the contents of nutrient and heavy metal in soil, fine root and foliage by 2 sites near Ulsan - Onsan industrial estate and 2 sites in limited development district are summarized as follows : 1. The average forest soil pH(A horizon) in Ulsan had been proceeded down to 3.73 in deciduous forest and 3.86 in coniferous forest in 1994 from 4.45 and 4.78 in 1987, respectively, which indicated serious soil acidification. As comparing soil pH among sites, Dongcheon coniferous forest(pH 4.57) in limited development district showed the highest values and Dangwol deciduous forest(pH 3.19) near Onsan industrial estate showed the lowest values in 1994. 2. Contents of exchangeable calcium in forest soils of limited development district where showed much higher soil pH than industrial estate were 3.5 times more in deciduous forest soil and 11 times more in coniferous forest soil than in industrial estate, and contents of exchangeable magnesium were also 4.5 and 5 times more in limited development district than in industrial estate, respectively. However contents of exchangeable aluminium which had been supposed more in forest soil of industrial estate were more in limited development district. 3. Contents of calcium and magnesium in fine root of deciduous trees(A hirsuta. Q. acutissima) were 3.6 and 1.7 times more in limited development district than in industrial estate, respectively, and those of coniferous trees(P. rigida, P. thunbergii) were 4.6 and 1.5 times more in Limited development district than in industrial estate, respectively. Also contents of calcium and magnesium in foliage of deciduous trees were 1.1 and 2.2 times more in limited development district than in industrial estate, respectively, and those of coniferous trees were 1.8 and 3.3 times more in limited development district, respectively. And contents of aluminium in fine root and foliage were nearly as same as in soil. 4. Ca/Al molar ratios in soil and fine root, which could be related with the dgree of soil acidification and Al toxicity on trees, were Less than 1 in all sites except Dongcheon, suggesting that the soil and fine root in the sites have high sensitivity to soil acidification and the decrease in nutrient uptake and root enlargement. The Ca/Al molar ratios in soil and fine root in coniferous forest were highly correlated with the soil pH one another. 5. Contents of Cu, Zn and Pb in soil, fine root and foliage were more in industrial estate than in limited development district in both deciduous and coniferous forests, however, oppositely contents of Mn and Cd in soil were more in limited development district than in industrial estate.
본 연구는 산림토양(山林土壤)의 산성화(酸性化)가 토양내 치환성 양이온($Ca^{2+}$, $Mg^{2+}$, $Al^{3+}$) 및 중금속(Cu, Zn, Mn, Pb, Cd) 분포(分布)에 미치는 영향을 평가하고, 이러한 토양내 화학적 특성과 임목의 세근과 엽내 양료 및 중금속 분포와의 관계(關係)를 파악하기 위하여 수행되었다. 이를 위하여 울산(蔚山)과 온산공단(溫山工團) 주변의 6개 조사구와 개발제한지역내(開發制限地域內) 2개 조사구를 대상으로 토양 pH의 장기적(長期的) 변화(變化)와 토양(土壤), 세근(細根) 및 엽(葉)내 양료(養料)와 중금속(重金屬) 함량(含量)을 조사한 결과는 다음과 같다. 1. 울산지역 산림의 토양 pH(A층)는 1987년에 활엽수림(闊葉樹林)과 침엽수림(針葉樹林)에서 각각 4.45와 4.78이었던 것이 1994년에는 각각 3.73과 3.86으로 감소하여 토양산성화(土壤酸性化)의 정도가 심화되었다. 1994 년 현재 개발제한지역내 침엽수림인 동천이 4.57로 가장 높은 반면 온산공단에 인접한 당월의 활엽수림이 3.19로 가장 낮았다. 2. 공단지역(工團地域)에 비해 토양 pH가 높았던 개발제한지역 산림의 토양내 치환성(置換性) $Ca^{2+}$함량은 공단지역보다 활엽수림에서 3.5배, 침엽수림에서 11배나 높았고, 치환성(置換性) $Mg^{2+}$ 함량 또한 각각 4.5배와 5배나 높았다. 그러나 공단지역에서 높을 것으로 예상되었던 치환성(置換性) $Al^{3+}$함량은 오히려 개발제한지역에서 높게 나타났다. 3. 세근내(細根內) Ca과 Mg 함량은 개발제한지역이 공단지역보다 활엽수(물오리나무, 상수리나무)의 경우 각각 3.6배와 1.7배 높았고 침엽수(리기다소나무, 곰솔)에서는 각각 4.6배와 1.5배 높았다. 엽(葉)에 있어서도 개발제한지역 산림의 활엽수가 공단지역보다 각각 1.1배와 2.2배 높았고, 침엽수는 각각 1.8배와 2.3배나 높았다. 그리고 세근과 엽내 Al 함량 역시 토양에서와 같은 경향을 보였다. 4. 토양산성화도(土壤酸性化度)와 임목(林木)에 대한 Al 독성(毒性)을 평가하기 위한 토양과 세근내 Ca/Al 몰비가 동천을 제외한 오든 조사구의 토양과 세근에서 1 이하로써 토양산성화에 민감할 뿐만 아니라 양료흡수(養料吸收) 및 근계발달(根系發達)의 피해(被害)가 예상되었다. 침엽수림(針藥樹林)의 경우 토양 pH와 토양 및 세근내 Ca/Al 몰비간에 서로 고도(高度)의 상관(相關)을 보였다. 5. 토양, 세근 및 엽내 Cu, Zn, Pb 함량은 활 침엽수림 모두에서 공단지역(工團地域)이 개발제한지역(開發制限地域)보다 전체적으로 높았지만, 토양중 Mn과 Cd 함량은 반대로 개발제한지역이 더 높았다.
(Department of Forest Resources, College of Agriculture, Chungnam National University)
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