Modeling the Production and Uses of Biological Resources from the Viewpoint of Energy Flow in a Rural Village in Sichuan,China

This study aimed at clarifying the impact of deforestation and afforestation on the quality of life in a village in Sichuan Province, China. We devised a conceptual model of bioresource production and use based on quantified energy flow. The basic structure of the model has three sectors: production, use, and externals. We developed comprehensive methodology to quantify the model. Bioresource use per person in 1997 was 3.7 GJ for food, 10.2 GJ for fodder, 0.2–0.4 GJ for building material, 12.8 GJ for fuel, and 1.8 GJ for fertilizer, totaling 28.6–28.8 GJ.We used four environmental indicators to evaluate bioresource production and use: a biological productivity indicator, a use-efficiency indicator, a supply–demand balance indicator, and a self-sufficiency indicator. Use of these indicators showed that supply-demand balance of fuel was dramatically improved from 30% to 85% by afforestation, but 99% of bioresource use still depends on domestic products. Thus, it is necessary to improve biological productivity and promote the efficient use of bioresources to achieve sustainable living in the area. Massive deforestation in the 1950s caused a direct shortage of building material and fuel wood. The shortage of wood led to a stagnation in the rebuilding of houses, and fuel wood was substituted with crop residues. Because crop residues had been used for fertilizer and fodder, their use as fuel caused a shortage of fertilizer and fodder. This was an indirect impact of deforestation on peoples quality of life.     

Using turbidity and acoustic backscatter intensity as surrogate measures of suspended sediment concentration in a small subtropical estuary

The suspended sediment concentration is a key element in stream monitoring, although the turbidity and acoustic Doppler backscattering may be suitable surrogate measures. Herein a series of new experiments were conducted in laboratory under controlled conditions using water and mud samples collected in a small subtropical estuary of Eastern Australia. The relationship between suspended sediment concentration and turbidity exhibited a linear relationship, while the relationships between suspended sediment concentration and acoustic backscatter intensity showed a monotonic increase. The calibration curves were affected by both sediment material characteristics and water quality properties, implying that the calibration of an acoustic Doppler system must be performed with the waters and soil materials of the natural system. The results were applied to some field studies in the estuary during which the acoustic Doppler velocimeter was sampled continuously at high frequency. The data yielded the instantaneous suspended sediment flux per unit area in the estuarine zone. They showed some significant fluctuations in instantaneous suspended mass flux, with a net upstream-suspended mass flux during flood tide and net downstream sediment flux during ebb tide. For each tidal cycle, the integration of the suspended sediment flux per unit area data with respect of time yielded some net upstream sediment flux in average.     

Dry weight, carbon and nitrogen components of caprellid amphipods (Crustacea) inhabiting the Sargassumyezoense community of Otsuchi Bay, northeastern Japan

Dry weight (DW), carbon (C) and nitrogen (N) contents in four species of caprellids, Caprella danilevskii, C. subinermis, C. penantis R-type, and C. verrucosa, inhabiting Sargassumyezoense (Yamada) in Otsuchi Bay, northeastern Japan, were measured based on live specimens. In all species males tend to grow larger than females in pereonite II length, which is used as an indicator of body length, and have greater dry weight, carbon and nitrogen contents. All three parameters (DW, C and N) had highly significant relationships against pereonite II length. Regressions of female pereonite II length against the three parameters significantly differed from males in the four species. Average percentages of carbon and nitrogen contents of the total dry weight ranged from 30.82 to 32.21% and 5.82 to 6.86%, respectively. The carbon/nitrogen ratio tended to decrease against increasing pereonite II length, e.g., 7.2 to 4.3 in C. danilevskii. Received: 25 November 1996 / Accepted: 31 July 1997