The temperature-dependent molecular chain movements and transitions of polystyrene-block-poly-(ethylene-co-1-butene)-block-polystyrene block copolymer (SEBS) above room temperature were studied by insite infrared spectroscopy combined with moving-window two-dimensional (MW2D) correlation spectroscopy. Some complex molecular chain movements and transitions of SEBS were revealed with the linear incremental temperature increasing (30-166 °C). The melting point of the extraordinary weak crystal of -(CH 2 -CH 2 )n in the poly(ethylene-co-1-butene) block (EB) is determined at 48 °C. The heat enthalpy relaxation of polystyrene block (S) of SEBS, which is induced by the framework movement of the side benzene ring and the melting of the weak crystal in the polystyrene block, is observed around 72-80 °C from the MW2D correlation spectrum. The glass transition temperature of the polystyrene block is determined around 120 °C. From the MW2D correlation spectrum, we discover that, around 120 °C, the chain segment movement of polystyrene block occurs before that of poly(ethylene-co-1-butene) block in phase interface. At 142 °C, the fundamental chains of the disperse phase (S block) center initiate to entirely move and this type of movement drives a fraction of the disperse phase (S block) to deform from an incomplete shape to a sphere. This corresponds to the entirely viscous flow temperature of the fundamental chains of the disperse phase.

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The assessment of biodiversity in managed plantations has become an important issue for long-term sustainability of the ecosystem. The continuous cropping system (CCS) is common practice in Eucalyptus plantations in southern China. In order to clarify the effects of such a practice on species compositions, species diversity, and functional type compositions of understory vegetation, a field trial was installed in the first and second rotations of Eucalyptus plantations. The treatments were replicated three times and arranged in a simple completely randomized design. Vegetation surveys were performed in 1998-2005 following the treatments. Although the CCS had no significant effect on the composition structures in terms of life-form, growth-form, seed dispersal strategies and breeding strategies, there were significant differences in percent coverages of shrub (SLC) and herbaceous layer (HLC) between two types of stand. The CCS reduced the species richness and species diversity remarkably, and was also particularly favorable for r-strategy herbaceous species at the expense of k-strategy woody species in understory vegetation. The repeated disturbances to soil and vegetation including clear-cutting followed by prescribed burning and mechanical plowing maybe the main factor which results in the negative change of understory plant diversity. Although more comprehensive studies on disturbance and a long-term monitoring of a broad-scale project will be required, we suggest that alternative silviculture, consisting of practices other than clear-cutting and prescribed burning, should be introduced to conserve species composition and diversity of Eucalyptus plantations.

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