[Variations of water use efficiency and foliar nutrient concentrations in Cunninghamia lanceolata plantations at different ages].

We studied water use efficiency (WUE), nitrogen (N) and phosphorus (P) status of leaves at different leaf ages (current year, 1-, 2-, and 3-year-old foliage) as well as their relationships in a subtropical chronosequence of Chinese fir (Cunninghamia lanceolata) forests (3-, 8-, 14-, 21- and 46-year-old). The results showed that foliar WUE varied significantly with foliar age in the order of current year foliage > 1-year-old foliage > 2-year-old foliage > 3-year-old foliage, while stand age had no significant impact on foliar WUE. Foliar N/P ranged from 11.

[Variations of water use efficiency and its relationship with leaf nutrients of different altitudes of Wuyi Mountains, China].

We determined the water use efficiency and nitrogen and phosphorus concentrations of plants at different altitudes (600, 900, 1300, 1500, 1800, 2000, 2100 m) in Wuyi Mountains to understand the relationship of water use efficiency with foliar nutrients. The results showed that plant water use efficiency increased with altitude, and the leaf δO of tree showed no significant variance with altitude. On the whole, leaf nitrogen concentration showed no obvious trend, while leaf phosphorus concentration at high altitude was significantly higher than that at low altitude.