[Effects of sewage sludge compost on the growth and photosynthetic characteristics of turfgrass].

The effects of different dosages (0, 0.8%, 2%, 6% and 10%) of sewage sludge compost on the growth and photosynthetic characteristics of three turfgrass, i. e., Festuca arundinacea, Lolium perenne and Poa pratensis were studied. The results showed that the dosage of 6% had the optimal effects. The plant height, leaf area and dry biomass of three turfgrass increased significantly with the increasing sewage sludge compost dosage, while the root/shoot ratio decreased obviously. Compared with the control, the plant height of F. arundinacea, L. perenne and P. pratensis increased by 64.9%-180.8%, 97.3%-200.9% and 39.1%-156.5%, the leaf area per plant increased by 91.3%-417.4%, 186.4%-394.9% and 164.6%-508.3% and the dry biomass per plant increased by 333.4%-867.6%, 138.4%-445.1% and 316.3%-669.2%, respectively. With the increasing dosage of sewage sludge compost, the net photosynthetic rate (Pn), transpiration rate (Tr), intercellular CO2 concentration (Ci) and water use efficiency (WUE) of F. arundinacea increased first and decreased then, the Pn, Tr and WUE of P. pratensis showed a significantly increasing trend, while the Ci decreased after an initial increase, and the Pn and WUE of L. perenne increased gradually, while the Ci and Tr decreased after a gradual increase. With the in- creasing sewage sludge dosage, the contents of chlorophyll a and b of the three turfgrass species increased markedly, and then decreased when the dosage was more than 6%, but the ratio of chlorophyll a/b was little changed.

[Carbon dynamics of broad-leaved Korean pine forest ecosystem in Changbai Mountains and its responses to climate change].

By using process model Sim-CYCLE based on dry matter production theory, this paper estimated the gross primary productivity (GPP), net primary productivity (NPP), net ecosystem productivity (NEP), ecosystem carbon storage (WE), total plant carbon storage (WP), and total soil carbon storage (WS) of broad-leaved Korean pine forest ecosystem in Changbai Mountains from 1982 to 2003, and analyzed the variations of these indices under present climate condition and carbon equilibrium state as well as the responses of these indices to climate change scenarios in the future. Under present climate condition, the estimated GPP, NPP, and NEP were 14.9, 8.7, and 2.7 Mg C x hm(-2) x a(-1), being 2.8 Mg C x hm(-2) x a(-1) less and 1.4 and 0.2 Mg C x hm(-2) x a(-1) higher than the measured values, respectively. The NEP in June-August occupied more than 90% of the annual NEP, and the maximum monthly NEP appeared in July (1.23 Mg C x hm(-2) month(-1)). The estimated WE, WP, and WS were 550.8, 183.8, and 367.0 Mg C x hm(-2), respectively, very close to the measured values. From present climate condition to carbon equilibrium state, the estimated carbon storages of the forest ecosystem increased to some extent, with the GPP and NPP being 17.7 and 7.3 Mg C x hm(-2) x a(-1), respectively, suggesting that the role of the forest ecosystem as a carbon "sink" declined gradually with the increase of carbon storage. A 2 degree C-increment of air temperature did not benefit the increase of GPP, NPP and NEP, while doubling CO2 concentration was in adverse. The effects of the combination of doubling CO2 concentration and 2 degree C-increment of air temperature on the GPP, NPP, and NEP were similar to those of doubling CO2 concentration. The climate change scenario in the future had the same effects both on the carbon storage and on the productivity of the forest ecosystem, which was mainly correlated to the effects of primary productivity on the carbon storage.