[Aboveground biomass of natural Castanopsis carlesii-Schima superba community in Xiaokeng of Nanling Mountains, South China].

By the method of clear cutting, a measurement was made on the aboveground biomass (AGB) of 24-year old natural Castanopsis carlesii-Schima superba community in an 800 m2 plot in Xiaokeng of Nanling Mountains, South China. The distribution patterns of the total AGB in different forest layers, tree species, and tree layer organs were investigated, and the AGB regression models were constructed. The results showed that when constructing the AGB regression models, more than 12 samples would be feasible. Based on the measured AGB of 265 felled trees, the AGB models of mixed broadleaved species were AGB = 0. 128D(2.372) and AGB = 242.331(D2H)(0.947). The single tree's AGB model of C. carlesii, S. superba, and Cunninghamia lanceolata was also established. The total AGB of the forest community was 115.20 t x hm(-2), of which, the AGB of tree layer, understory layer, liana, and litter layer was 111.25, 1.01, 0.36, and 2.58 t x hm(-2), respectively. The AGB of C. carlesii and S. superba took up 39.1% and 28.7% of the tree layer AGB, respectively. The AGB of tree stem and branch-leaf occupied 81.0% and 19.0% of the tree layer AGB, respectively.

[Effects of montelukast on atherosclerosis and monocyte chemoattractant protein-1 expression in ahypercholesterolemic rabbit model.].

OBJECTIVE: To investigate the effects of montelukast on atherosclerosis and monocyte chemoattractant protein-1 expression in a hypercholesterolemic rabbit model. METHODS: Thirty four male New Zealand white rabbits were randomized into four groups including normal control group (n = 6), placebo group (n = 8), atorvastatin group (1.5 mgxkg(-1)xd(-1), beginning at 8(th) weeks for 4 weeks, n = 10) and montelukast group (1 mgxkg(-1)xd(-1), beginning at 8(th) weeks for 4 weeks, n = 10). Rabbits except those in normal control group were fed a high cholesterol diet for 12 weeks. Serum lipids were measured at 0, 8 and 12 weeks after intervention. The intima/media ratio, percentages of macrophages or smooth muscle cells in intima and the expression of MCP-1 mRNA were examined. RESULTS: Atherosclerosis was evidenced in placebo group and atorvastatin or montelukast treatment significantly reduced neointima (0.32 +/- 0.12 and 0.34 +/- 0.10 vs. 1.12 +/- 0.36, P < 0.05) and macrophage content [(9.8 +/- 4.6)% and (11.2 +/- 3.7)% vs. (34.6 +/- 8.8)%, P < 0.05], increased SMC content [(18.6 +/- 6.9)% and (19.2 +/- 8.6)% vs. (5.2 +/- 2.3)%, P < 0.05] and inhibited expression of MCP-1 mRNA (0.42 +/- 0.08 and 0.40 +/- 0.06 vs. 2.36 +/- 0.48, P < 0.01). Montelukast had similar anti-atherogenetic effects as atorvastatin but had no influence on plasma lipids. CONCLUSIONS: Montelukast could attenuate atherosclerosis in this hypercholesterolemic rabbit model which might be attributed to its anti-inflammatory effects.

Sap flow response of Eucaylyptus (Eucalyptus urophylla) to environmental stress in South China.

Sap flow and environmental conditions were monitored at two Eucalyptus (Eucalyptus urophylla S.T.Blake) plantations at Hetou and Jijia, located in Leizhou, Zhanjiang, Guangdong Province. It was found that daily sap flux density (SFD) of Eucalyptus was closely related to daily atmospheric vapor pressure deficit (VPD) (R2 = 0.76, P = 0.01 at Hetou and R2 = 0.7021, P = 0.01 at Jijia) at both sites. No significant relationship existed between daily SFD and mean daily air temperature at both sites. Daily SFD varied with wind speed Y = -17585X3 + 15147X2 - 1250.7X + 2278.4 (R2 = 0.68; P = 0.01) at Hetou and Y = -101.67X3 - 1.65X2 - 376.4X + 1914.8 (R2 = 0.40, P = 0.05) at Jijia, where Y was daily SFD, X was daily wind speed. Experimental observations yielded the following data: (1) the critical lower and upper daily VPD threshold were 0 and 2 kPa, within which daily SFD varied from 540+/-70 L/(m2.d) to 4739+/-115 L/(m2.d) at Hetou site, from 397+/-26 L/(m2.d) to 3414+/-191 L/(m2.d) at Jijia site; (2) Diurnal SFDs at Hetou site were much higher under low relative humidity (< 30%) and slightly lower under high relative humidity (> 80%) compared with those at the Jijia site; (3) The upper and lower threshold of daily and diurnal RAD for the optimal water use of E. urophylla plantations were 18+/-2.7 and 2+/-1 MJ/(m2.d), 669 and 0 J/(cm2.h) during the observation period.