The scaling of respiratory metabolism with body mass is one of the most pervasive phenomena in biology. Using a single allometric equation to characterize empirical scaling relationships and to evaluate alternative hypotheses about mechanisms has been controversial. We developed a method to directly measure respiration of 271 whole plants, spanning nine orders of magnitude in body mass, from small seedlings to large trees, and from tropical to boreal ecosystems. Our measurements include the roots, which have often been ignored. Rather than a single power-law relationship, our data are fit by a biphasic, mixed-power function. The allometric exponent varies continuously from 1 in the smallest plants to 3/4 in larger saplings and trees. Therefore, our findings support the recent findings of Reich et al. [Reich PB, Tjoelker MG, Machado JL, Oleksyn J (2006) Universal scaling of respiratory metabolism, size, and nitrogen in plants. Nature 439:457–461] and West, Brown, and Enquist [West GB, Brown JH, Enquist BJ (1997) A general model for the origin of allometric scaling laws in biology.Science276:122 -126.]. The transition from linear to 3/4-power scaling may indicate fundamental physical and physiological constraints on the allocation of plant biomass between photosynthetic and nonphotosynthetic organs over the course of ontogenetic plant growth.

This study proposes a simple method for stand volume estimation by combining low laser-sampling density Light Detection and Ranging (LiDAR) data (i.e. 1 hit per 4 m²) with high-resolution optical imagery (i.e. 0.6 m) in coniferous plantations. The study area was in closed-canopy, mountainous, Japanese cedar (Cryptomeria japonica) plantations on undulating terrain at an elevation of 135–391 m above sea level. A total of 25 circular plots (0.04 ha) were established and stand volumes within plots were investigated in the field. The field-measured, plot-level stand volume ranged from 262.8 to 984.0 m³ ha⁻¹ and the average value was 555.7 m³ ha⁻¹. We used the measurements as validation data to evaluate estimates derived from an empirical regression model that was constructed on the basis of the allometry between crown diameter and diameter at breast height (DBH) from previous research. As a result, stand volume at various stand conditions could be estimated precisely regardless of different laser footprint sizes of 0.16–0.47 m when combining low-density LiDAR data with QuickBird panchromatic imagery. The maximum random error and root mean square error (RMSE) in stand volume estimates by data combination were 10% and 39% of the average stand volume, respectively. Thus, this method based on allometry and using low-density LiDAR data and high-resolution optical imagery could be capable of offering precise stand volume estimates in coniferous forests in different localities.

We analyzed data from 28 long-term experimental monitoring plots installed in Japanese cedar (Cryptomeria japonica D. Don) plantations in northeastern Japan to examine how site productivity and thinning practices relate to culmination in stand growth. Site productivity and thinning practices in the plots were evaluated by site index (dominant tree height at 40-years old) and by cumulative thinning rate (cumulative thinning volume divided by cumulative gross production during the entire period of measurement). Culmination of stand growth was evaluated by culmination age of the mean annual increment (MAI) and its maximum value (Max MAI). Max MAI for the mean annual gross increment (MAIgross) and mean annual net increment (MAInet) increased with increasing site index, but did not change with cumulative thinning rate. Culmination age for MAIgross decreased with increasing site index, but did not change with cumulative thinning rate. Culmination age for MAInet decreased with increasing site index. Additionally, culmination age for MAInet increased with increasing cumulative thinning rate in sites with a high site index (>19.3 m) but not in those with a low site index (<19.3 m). These results indicate that thinning extends the culmination age without changing Max MAInet under high site productivity. Therefore, thinning increases total net yield in sites with high productivity based on a long-term perspective.

A model for net primary productivity (NPP) estimation was developed based on a relationship between NPP estimated by the Chikugo model and the intensity-sum of the normalized difference vegetation index (NDVI) multiplied by the solar radiation during growth periods. There was a clear linear relationship between the estimated NPP and the intensity-sum (R ²=0.845), whose slope indicated the average light use efficiency (LUE) of global plants. The NPP estimation model (NDVI-based model), which included growth multipliers of optimum air temperature and soil water stress on vegetation growth with LUE, was developed. NDVI anomalies caused by scattering of volcanic ash from Mt Pinatubo were reduced by a correction based on intensity matching of channels 1 and 2 individually. NDVI retrieved a seasonal change pattern in 1991 and 1992 after the correction. Global NPP between 1988 and 1993 was estimated using the NDVI-based model, corrected NDVI, air temperature and soil water content data. There was a linear relationship between the estimated NPP and NPP observed in forests in China. The average global NPP during the 6 years was about 123 Pg dry weight per year, and the maximum and minimum NPP appeared in 1991 and 1988, respectively.