海岸景观防护林群落对堤岸土壤化学的生态效应

采用定位对比试验方法,连续2年按季节对比监测广州市南沙区沿海防护林（海岸防护林、河涌水网防护林、路网防护林）土壤与岸堤撂荒地土壤、土壤水分与林缘江水中K＋、Na＋、Mg、Cl-、SO42-、HCO3-、Pb、Cd的含量,研究海岸景观防护林群落对岸堤土壤盐分、重金属元素的生态修复作用。结果表明：①与林缘江水相比,防护林土壤水分中K＋、Na＋、Cl-、SO42-平均含量分别减小约66.2%、28.8%、34.9%、17.5%,有效地改善了土壤水体钠盐、钾盐的含量。②防护林群落土壤水、林缘江水中Pb与Cd的年均含量依次为：江水〉海岸防护林〉河涌水网防护林〉路网防护林;相对于林缘江水,防护林土壤水分中Pb、Cd平均含量分别减小约38.0%、68.2%。③相对于堤岸撂荒地土壤,防护林群落土壤中K＋、Na＋、Cl-、SO42-、HCO3-平均含量分别减小约66.5%、63.8%、63.9%、76.8%和11.2%;3种防护林群落间K＋、Na＋、Cl-、SO42-、HCO3-的含量差异显著,即路网防护林〉河涌水网防护林〉海岸防护林,且相对撂荒地土壤Cd的平均含量减小率分别达到72.8%、57.6%、77.5%,表现出显著的土壤化学生态修复效应。④3种防护林土壤的盐分离子含量在季节上、土壤层上未表现出显著差异;土壤Pb、Cd含量在土层间的差异也不显著,、但在年内季节上的差异极显著。总体来看,海岸景观防护林能够有效缓解珠江口土壤盐分和重金属的侵蚀,在沿海地区发挥着重要的生态修复作用。

Ecological benefits from protective forest communities to soil chemistry in Nansha district, a coastal area of Guangzhou city

A comparative trial was used in the present study. We measured the concentrations and seasonal variations of K＋, Na＋, Mg, CI-, 5042, HCO3-, Pb and Cd in soil and soil water in three coastal protective forests located in Nansha district, Guangzhou city. The monitored concentrations in these thee forests （i.e., water channel forest, windbreak forest, and isolating forest） were compared with the Pearl River and uncovered land, respectively. We also detected the ecological restoration of soil salinities and heavy metals by these protective forests. The results showed that mean concentrations of K~, Na~, CI and SO42- in soil water of the three protective forests decreased by 66.2%, 28.8%, 34.9% and 17.5%, respectively, which bettered water quality in soil via salinity reduction. Secondly, the concentrations of Pb and Cd exhibited a similar distribution pattern, highest in the Pearl River, followed by windbreak forest, water channel forest and isolating forest. The average concentrations of Pb and Cd in the three protective forests decreased by 38.0% and 68.2% respectively, compared with that of in the Pearl River. Thirdly, the concentrations of K＋, Na＋, CI-, SO42- and HfO3- in soil water under the protective forests also exhibited a similar distribution pattern, highest in the isolating forest, followed by water channel forest and windbreak forest. The average concentrations decreased by 66.5%, 63.8%, 63.9%, 76.8% and 11.2%, respectively, when compared with that of under the uncovered land. The concentration of Cd in these forests decreased by 72.8%, 57.6% and 77.5%, compared with the uncovered land. Lastly, no significant difference in these salinities was detected, neither among different seasons nor soil layers, in the three protective forests in the present study. Though no significant difference was detected in Pb and Cd among soil layers, the seasonal variations of the two heavy metals were of significant difference. In conclusion, protective forest communities can decrease the concentrations of salinity and heavy metals, and protect the coastal area from environment hazards.