water pine
2.A new bioassay way designed to Bursaphelenchus xylophilus was studied. The blocks with the dia of 3cm and thickness of 0.5cm was adopted. The testing showed that blocks containing 40-60% water, with 300 pine wood nematodes being inoculated per block, 8-day darkness cultivation under the temperature of 25 degrees Celsius was the optimum condition.
9.Soil incubation experiments were conducted in lab to delineate the effect of soil temperature and soil water content on soil respirations in broad-leaved/Korean pine forest(mountain dark brown forest soil),dark coniferous forest(mountain brown coniferous forest soil)and ermans birch forest(mountain soddy forest soil)in Changbai Mountain in September 2001.The soil water content was adjusted to five different levels(9％,21％,30％,37％ and 43％)by adding certain amount of water into the soil cylinders,and the soil sample was incubated at 0,5,15,25 and 35 ℃ for 24 h The results indicated that in broad-leaved/Korean pine forest the soil respiration rate was positively correlated to soil temperature from 0 to 35 ℃.Soil respiration rate increased with increase of soil water content within the limits of 21％ to 37％,while it decreased with soil water content when water content was over the range.The result suggested the interactive effects of temperature and water content on soil respiration.There were significant differences in soil respiration among the various forest types.The soil respiration rate was highest in broad-leaved/Korean pine forest,middle in ermans birch forest and the lowest in dark coniferous forest.The optimal soil temperature and soil water content for soil respiration was 35℃ and 37％ in broad-leaved/Korean pine forest,25 ℃ and 21％ in dark coniferous forest,and 35 ℃ and 37％ in ermans birch forest.Because the forests of broad-leaved/Korean pine,dark coniferous and ermans birch are distributed at different altitudes,the soil temperature had 4-5 ℃ variation in different forest types during the same period.Thus,the soil respiration rates measured in brown pine mountain soil were lower than those in dark brown forest and those measured in mountain grass forest soil were higher than those in brown pine mountain soil.
为了研究土壤温度和土壤含水量对阔叶红松林(山地暗棕壤)、云冷杉暗针叶林(山地棕针叶林土壤)和岳桦林(生草森林土)的土壤呼吸的影响,于2001年9月在长白山进行了土壤实验.利用增加土壤样柱的含水量,将土壤含水量分为9％,、21％、30％、37％和43％5个等级,土壤样品分别在0、5、15、25和35℃的温度下保持24小时.阔叶红松林土壤在0(35℃范围内,土壤呼吸速率与温度呈正相关.在一定的含水量范围内(21％(37％),土壤呼吸随含水量的增加而升高,当含水量超出该范围,土壤呼吸速率则随含水量的变化而降低.土壤温度和水分对土壤呼吸作用存在明显的交互作用.不同森林类型土壤呼吸作用强弱存在显著差异,大小顺序为阔叶红松林>岳桦林>云冷杉暗针叶林.红松阔叶林土壤呼吸作用的最佳条件是土壤温度35℃,含水量37％;云冷杉暗针叶林下的山地棕色针叶土壤呼吸作用的最佳条件是25℃,21％;岳桦林土壤呼吸作用的最佳条件是35℃,含水量37％.但是,由于长白山阔叶红松林,云冷杉林和岳桦林处在不同的海拔带上,同期不同森林类型土壤温度各不相同,相差4~5℃,所以野外所测的同期的山地棕色针叶林土呼吸速率应低于暗棕色森林土呼吸速率,山地生草森林土呼吸速率应高于山地棕色针叶林土的呼吸速率.图2表1参25.收藏指正
