Allometric models for aboveground biomass of six common subtropical shrubs and small trees

The aboveground biomass(AGB)of shrubs and small trees is the main component for the productivity and carbon storage of understory vegetation in subtropical secondary forests.However,few allometric models exist to accurately evaluate understory biomass.To estimate the AGB of five common shrub(diameter at base<5 cm,<5 m high)and one small tree species(<8 m high,trees’s seedling),206 individuals were harvested and species-specific and multi-species allometric models developed based on four predictors,height(H),stem diameter(D),crown area(Ca),and wood density(ρ).As expected,the six species possessed greater biomass in their stems compared with branches,with the lowest biomass in the leaves.Species-specific allometric models that employed stem diameter and the combined variables of D~2H andρDH as predictors accurately estimated the components and total AGB,with R^(2) values from 0.602 and 0.971.A multi-species shrub allometric model revealed that wood density×diameter×height(ρDH)was the best predictor,with R^(2) values ranging from between 0.81 and 0.89 for the components and total AGB,respectively.These results indicated that height(H)and diameter(D)were effective predictors for the models to estimate the AGB of the six species,and the introduction of wood density(ρ)improved their accuracy.The optimal models selected in this study could be applied to estimate the biomass of shrubs and small trees in subtropical regions.

Bill Morphology Does Not Influence Vocal Performance in Darwin’s Small Tree Finch on Floreana Island

Bird song is used for mate attraction and is important for establishing reproductive isolation. Current research highlights performance constraints on song production that may be influenced by variation in bill morphology. Darwin＇s finches are a model system for studying the relationship between morphology and song performance, with previous studies suggesting that lower vocal performance is correlated with larger bill size. Here, we tested for a relationship between bill morphology and vocal performance in Darwin＇s Small Tree Finch （Camarhynchus parvulus） on Floreana Island. We found no evidence of a correlation between bill morphology and vocal performance. This finding is in agreement with prior study of the Small Tree Finch, but contrasts a greater body of work addressing song in Darwin＇s Finches. We discussed our findings in the context of ecological divergence, and ecological variation across species.

Environmentally sound timber extracting techniques for small tree harvesting

Due to large area disturbed and great deal of energy cost during skidding operations, introducing or applying the appropriate techniques of timber extracting could significantly reduce the impact of timber extraction operations to forest environment while pursuing the reasonable operation costs. Four environmentally sound timber extraction techniques for small tree harvesting, particularly for thinning operations, were presented and introduced in this paper. The results of evaluation, test or practices indicated that these timber-extracting techniques are feasible, applicable and reasonable in small tree harvesting with a relatively low impact no environment and a moderate operation cost.