& Background This study was designed to evaluate the internal nutrient cycling of litterfall in different elevation subtropical forests of Central Taiwan. & Methods The litterfall of evergreen hardwoods at three elevations, specifically Mt. Peitungyen (2,078 m), Hui-Sun experimental forest (HSEF) (1,066 m), and Lienhauchi (782 m) in central Taiwan, was collected monthly using traps and sorted into leaves, twigs, reproductive litter, and miscellaneous material. In addition, the litter on the forest floor was collected trimonthly. All the samples were weighed and measured for C, N, P, K, Ca, and Mg concentrations and fluxes from March 2009 to February 2010. & Results The annual litterfall productions were 6.58, 8.24, and 9.17 Mg ha −1 year −1 at Mt. Peitungyen, HSEF, and Lienhauchi, respectively. At more than 60 %, leaves were the main component of the total litterfall. There was smallest decomposition constant (0.487) at Mt. Peitungyen. The nutrient fluxes increased as elevation decreased. The litterfall correlated positively with rainfall at Lienhauchi, with temperature at HSEF, and with temperature and rainfall at Mt. Peitungyen. & Conclusion The annual litterfall decreased with an increase in elevation. The turnover rate was faster at HSEF than at Mt. Peitungyen. Thus, the forest managers should pay more attention to understand and monitor plant community responses to global warming and nutrient loss.

Odor is one of the most distinctive characteristics of wood. Woods in the family Taxodiaceae and Cupressaceae often emit fragrant odors. In this study, the fragrance compounds of six coniferous woods grown in Taiwan, namely Chamaecyparis formosensis, Chamaecyparis obtusa var. formosana, Calocedrus macrolepis var. formosana, Taiwania cryptomerioides, Cunninghamia lanceolata, and Cryptomeria japonica, were studied by solid-phase microextraction and GC/MS. A non-biased overall profile of the fragrance compositions of the woods was obtained. The major aroma compounds were: b-elemene (15.8%), g-cadinene (12.1%), a-pinene (11.1%), and limonene (10.8%) in C. obtusa; myrtenol (27.0%), myrtenyl (19.2%), and g-cadinene (11.4%) in C. formosensis; b-cedrene (22.3%), d-cadinene (17.6%), and widdrene (11.4%) in T. cryptomerioides; b-cedrene (26.2%) a-pinene (19.7%) and limonene (13.2%) in C. lanceolata; 3-carene (21.0%), p-cymene (11.0%), and limonene (9.5%) in C. japonica; and p-cymene (24.4%), terpinen-4-ol (16.6%), and a-terpineol (12.5%) in C. macrolepis. The results may provide useful information for future studies on chemotaxonomy and metabolomics of conifers.

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This study examined the importance of the antioxidative defense mechanism during the application of simulated acid rain (SAR) pH 4, pH 3, pH 2, and pH 6 as control treatment in Cinnamomum philippinense seedlings. Analysis was carried out on 1, 10, and 15 days of spraying SAR. In our results, catalase (CAT), ascorbate peroxidase (APx), guaiacol peroxidase (GPOD), and glutathione reductase (GR) activity significantly were induced on 1 day of spraying SAR pH 3 and pH 2, suggesting that C. philippinense seedlings exposed to pH 3 and pH 2 acid rain for only 1 day were under oxidative stress, and antioxidant enzyme were apparently increased until 10 days of spraying SAR pH 4. However, on 10 days of spraying SAR pH 2, the accumulated intensity of acidity significantly inhibited the activities of CAT and APx accompanying with increased concentrations of malonydialdehyde (MDA). On the contrary, GPOD activity and the ascorbic acid ratio were remarkably increased when spraying SAR pH 2 for 15 days. Therefore, GPOD and ascorbate contribute to the scavenging of ROS at stronger acidity stresses. However, they were not enough to avoid cellular damage, since membrane lipids were injured, and necrosis appeared.

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