Relationship between tree species diversity and water holding capacity of litter layer in subtropical region.

Litter layer, serving as the "skin" of forest soil, plays a crucial role in conserving water resources and maintaining soil and water conservation. We analyzed the relationship of tree species richness, community weighted mean traits, and functional diversity with the standing mass, maximum water holding rate, and effective water sto-rage capacity of litters from various tree species including Liquidambar formosana, Mytilaria laosensis, Castanopsis sclerophylla, Castanopsis hystrix, Cunninghamia lanceolata, Pinus massoniana, Fokienia hodginsii, Taxus wallichiana and their combinations of mixed forests in subtropical region. The results showed that across various tree species combinations, the ranges of maximum water holding rate, standing litter mass and effective water storage capacity of undecomposed layer were 0-419%, 0-0.58 t·hm-2, and 0-1.66 t·hm-2, respectively. For the semi-decomposition layer, these values spanned in 0-375%, 0-6.14 t·hm-2, and 0-16.03 t·hm-2, respectively. Tree species richness and community weighted mean specific leaf area had significantly positive effects on standing mass of litter and effective water storage capacity, while community weighted mean leaf N content had significantly negative effect on standing mass of litter. The maximum water holding rate increased with the increases of functional diversity of specific leaf area and community weighted mean specific leaf area, decreased with the increase of community weighted mean leaf thickness. Results of structural equation model showed that tree species richness increased litter water holding capacity by increasing functional diversity of specific leaf area. The community weighted mean specific leaf area increased the water holding capacity of litter layer by increasing standing mass of litter and the maximum water holding rate. It is necessary to consider planting mixed forest with higher community weighted mean specific leaf area in the management of subtropical artificial forest, so as to improve the water holding capacity of litter layer.

[Study on the disabilities in aged 0-7 years children in Shenzhen, China].

OBJECTIVE: To explore the prevalence of vision, mental, audibility, language, psychiatry, extremity, and influence factors in the 0 - 7 year olds. METHODS: A total number of 77,727 0 - 7 year old children living in Shenzhen city were tested with tree phase screening under the Chinese standard of evaluation in disabilities. RESULTS: The prevalence of all disabilities was 5.59 per thousand (adjusted rate was 8.49 per thousand with a false negative of 3.1 per thousand ). The prevalence of mental disease was the highest (1.88 per thousand, with adjusted rate 3.43 per thousand ), the prevalence of language disability was 1.88 per thousand (including retarded language development, with adjusted rate 3.43 per thousand ). The prevalence rates of psychiatry, extremity and audibility disability were 1.59 per thousand, 1.56 per thousand, 1.11 per thousand respectively with of vision the lowest (0.37 per thousand ). The prevalence of all disabilities, audibility, language and mental was on the increase with age. The difference was statistically significant. Among all different age groups regarding psychiatric disease, the highest fell in the 2 - 4 year olds. The prevalence of extremity was not statistically different among age groups. The suspected agents of disease which occurred before or during pregnancy took up 45.7%. CONCLUSION: The prevalence of six kinds disabilities in Shenzhen was about 10 per thousand lower than that of the samples of the nation in 1989, but two times higher than that of similar studies in Japan. The prevalence rates of language and psychiatric disease were higher than that of the nation in 1989. The causation should be further studied.