Forest responses to the large-scale east coast fires in Korea

The east coast forest fires of April 2000 were Koreas largest recorded fires. This, along with the fact that they took place in the region most frequently affected by fire, attracted a great deal of attention. Due to the variations in wind, topography and pre-fire forest stands, a heterogeneous landscape mosaic of burn severity was created across the region. It turned out to be an excellent opportunity to study various landscape-scale impacts of fires on forest dynamics. Therefore, we investigated stands in the 23794ha of burned forest region, in terms of burn severity, vegetation regeneration and forested landscape change as a measure of community stability. Using the geographic information system technique, we analyzed the differential severity and post-fire recovery of pre-fire forest types of different stand age both at stand and species level. Analysis showed that pre-fire vegetation was composed of mainly pine (Pinus densiflora) stands that occupied 70% of the whole forested area, while pine-hardwood and hardwood stands occupied only 28% and 3%, respectively. In addition, two-thirds of all stands were less than 30-years-old. Pine stands were the most severely burned, while conversely pine-hardwood and hardwood stands were less vulnerable. This implied that pine forests had fire-prone characteristics. Vegetation recovery went the opposite way; that is, the regenerating vegetation cover was 71% at pre-fire hardwood stands, and 65% and 53% at pine-hardwood and pine stands, respectively. However, these recovery rates were strikingly fast, considering that investigation took place about 3months after the fires. Fire did not initiate successional processes, but tended to accelerate the predicted successional changes by releasing pre-fire understory species that survived the fires and regenerated by sprouting. The dominant pre-fire tree species (P. densiflora) was susceptible to fire and not resilient enough to reestablish in competition with oak species. Contrary to pines, the abilities of oak species, mainly Quercus mongolica and Q. variabilis, to survive fires and to resprout vigorously made them dominant at most post-fire stands. These shifts in species abundance caused drastic changes to the landscape: from pine-dominated to oak-dominated stands without any notable change in species composition. The patterns in forest regeneration that we observed in Korea may be representative of forest responses to any long-term repeated disturbances, including fire.     

温、湿度对家白蚁初建群体的影响

本文主要研究温、湿度因子对家白蚁初建群体的影响,实验指出家白蚁初建群体对温度及栖息地基质含水量要求严格,温度过高或过低都不利于种群发展,在20℃定温环境下,虽然能产几粒卵,但不能孵化。在25℃定温虽能产卵,但推迟孵化,影响以后种群数量的变动。家白蚁初建群体还要求基质含水量适中,过低的基质含水量,产卵量少且不能孵化,基质含水量过高,雌、雄虫死亡率亦高。实验室内要求的条件与野外群体飞行时要求的温湿度条件基本上是吻合的。     

狩猎库蚊生理年龄与班氏丝虫传播关系

国内外丝虫病之研究资料甚多,其中涉及蚊方面之内容亦屡见不鲜,最近Laurence(1963)更以阳性蚊体内所含各期丝虫幼虫比例推算出蚊之每日死亡率。唯自蚊之生理年龄来分析其与传病关系者甚少,仅见于Samarawickrema(962)及Wharton(1959)。自苏联 Детинва以卵巢小管膨大测定接蚊之生理年龄后,疟疾之有关流行病学研究得以深入发展,为防治该病提出许多有价值的资料。其后,学者们将此法应用于其他蚊种,亦证