Abstract: A 24-hour seasonal observation was conducted on the 4 factors reflecting urban forest ecological heath function (decreasing atmospheric particulate matters (PMs), declining airborne microbes, increasing aeroanions, and increasing biogenic volatile organic compounds (BVOCs)) in three typical urban forests in West Mountain of Beijing, and an analysis was made on the interrelationships between these factors, aimed to understand the ecological health function of urban forest. There existed close relationships between these four factors. The four sizes of atmospheric PMs had significant positive relationships each other, among which, PM_2.5 and PM_1.0 had the highest correlation, followed by total suspended particulate (TSP) and PM₁₀. The larger the difference in particulate size, the weaker the correlation was. The airborne bacteria were significantly positively correlated with the PMs, especially with the TSP. The aeroanions had a negative relationship with the PMs, and this relationship became stronger when the particulate size increased. The aeroanions had inhibitory effect on the airborne microbes, and this effect was more obvious on bacteria than on fungi. In Platycladus orientalis and Cotinus coggygria forests, BVOCs played definite roles in inhibiting airborne microbes and increasing aeroanions, and also, had definite association with PMs, but these effects varied with the components of BVOCs.

Key words: soil microbial community, simulated warming, alpine timberline, nitrogen and phosphorous, phospholipid fatty acid., soil carbon