摘要
利用 4年 (1 999～ 2 0 0 2 )的雾观测资料 ,对西双版纳热带季节雨林内雾特征进行了观测研究。结果表明 ,雾首先形成于最上林冠层 ,林下雾是由上层雾变浓、下沉而来。夜间 ,雾形成前 ,气温高于叶表温 ;雾形成后 ,气温则低于叶表温。热带雨林内各季节雾日数和雾日频率均高于无林地。热带雨林内平均全年雾日数可达 2 5 8d ,其中雾季和干热季共占 1 5 4d(5 9.6 % ) ,而雾季的雾日频率高达 90 %。雾日数的季节变化与各季节雨量呈明显的负相关。雾季 ,雾在 2 3∶0 0左右生成 ,比干热季、雨季分别提前 0 .7、2 .3h ,而消散时间则分别推迟 0 .8、2 .2h。雾生成和消散时间呈现出较明显的负相关。雾季雾的持续时间达 1 2 .2h·d-1 ,比干热季、雨季分别长 1 .5、4 .6h·d-1 。全年雾总持续时间占全年时间的 39.7% ,而雾季的相应值为 5 0 .8%。雾的形成不仅凝结了水汽进入森林 (全年 89.4mm) ,同时也对森林起到了一定的保温作用 。
Fog frequency and duration were measured between November 1998 and February 2003 in a seasonal rain forest in Xishuangbanna, Southwest China. The amount of fog and dew precipitation was measured daily using twelve bottle_funnel collectors set in a random pattern on the forest floor. Related microclimatic variables including air temperature, relative humidity, wind speed, solar radiation and rainfall were recorded by a meteorological observation system mounted on a 72 m tall meteorological tower in the study site. At night the fog occurred first at the top layer of the canopy, and then a thick fog penetrated the understory. Before fog occurred, the air temperature was greater at 0.5 m above the canopy than on the canopy surface but was lower after fog occurred. The number of fog days was much higher inside the rain forest (258 days/year) than in open areas (188 days/year). Fog frequency in the rain forest was 90% during the foggy season (November-February), slightly lower (78.7%) in the dry_hot season (March-April), and lowest (55.4%) in the rainy season (May-October). The number of fog days in each season was negatively correlated with the amount of rainfall. The onset of fog occurred on average at 2 300 and lifted at 1 100 hours during the foggy season. During the dry_hot season and rainy season, the fog occurred 0.7 and 2.3 hours later and lifted 0.8 and 2.2 hours earlier, respectively. Meanwhile, there was a negative correlation between the time of fog occurrence and lift. Average fog duration per day during the foggy season was 12.2 hours, and was 1.2 and 1.6 times longer than average fog duration of the dry_hot and rainy season, respectively. During the study period, the absolute amount of mean annual fog and dew precipitation was (89.4±13.5) mm (mean±SD), which was 4.9%±1.7% of the annual precipitation. Of the total annual amount of fog and dew precipitation, 85.9%±6.6% was collected during the foggy season and dry_hot season. The results suggest that fog, which both condenses water vapor into available precipitation in the forest and buffers temperature changes, plays an important role in the hydrology of the forest, especially during the foggy and dry_hot seasons. Therefore, horizontal precipitation (fog interception) needs to be included in calculations of the water balance in this forest. These results also demonstrate the importance of understanding the impacts of climate factors, and have important implications for ecologists and hydrologists interested in fog_inundated ecosystems.
出处
《植物生态学报》
CAS
CSCD
北大核心
2004年第2期264-270,共7页
Chinese Journal of Plant Ecology
基金
国家自然科学基金 ( 3 0 10 0 0 19)
云南省应用基础研究基金 ( 2 0 0 1C0 0 2 3Q和 2 0 0 3C0 0 0 9Z)
中国科学院知识创新工程重大项目(KZCX1_SW_0 1_0 1A)
关键词
西双版纳
热带季节雨林
雾
频率
雾季
干热季
雨季
小气候特征
森林
Fog frequency, Fog duration, Fog interception, Microclimatic factors, Tropical seasonal rain forest
