Akio Hagihara

Aboveground biomass of tropical rain forest stands in Indonesian Borneo

Aboveground plant biomass was examined in a tall virgin tropical lowland evergreen rain forest dominated by Dipterocarpaceae in Sebulu, East Kalimantan, Indonesia, with special reference to the gap-, building- and mature phases of the forest growth cycle. From the records of dimensions of sample trees examined by the stratified clip technique and DBH inventory data of trees in a study plot, the biomass of larger trees (DBH ≥4.5 cm) was estimated by the allometric correlation method. The biomass of smaller plants (DBH < 4.5 cm) was estimated by harvesting the plants in small quadrat plots. Although large differences were found between aboveground-biomass-estimates in different patches of different growth stages, the aboveground biomass in a 1.0 ha plot was 509 t/ha, and the one-sided LAI was 7.3 ha/ha. These values seem to result from the tall forest architecture with huge emergent trees (over 70 m high) and a moderate packing of plant mass indicated by the basal area value of 38.8 m2/ha for trees with DBH ≥4.5 cm.

Mixed-power scaling of whole-plant respiration from seedlings to giant trees

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. Science 276:122 -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.

Allometric relationships for estimating the aboveground phytomass and leaf area of mangrove Kandelia candel (L.) Druce trees in the Manko Wetland, Okinawa Island, Japan

Allometric relationships for estimating the phytomass of aboveground organs (stem, branches, leaves and their sum) and the leaf area in the mangrove Kandelia candel (L.) Druce were investigated. The variable D0.12H (D0.1 stem diameter at a height of H/10, H tree height) showed better accuracy of estimation than D2 (D, DBH) or D2H. A moderate relationship was found when the branch weight, leaf weight and leaf area were plotted against DB2 (DB stem diameter at a height of clear bole length). A strong linear relationship was found between leaf area and leaf weight (R2=0.979). The aboveground weight (wT) showed a strong relationship when plotted against D0.12H (R2=0.958), but very weak relationships were obtained against D2 (R2=0.300) and D2H (R2=0.316). The wT also showed a proportional relationship (R2=0.978) to D0.12H with a proportional constant of 0.04117 kg cm−2 m−1 (R2=0.978). Taking into account the allometric relationships of the weight of aboveground organs or leaf area per tree to different dimensions, such as D2, D2H, DB2 and D0.12H, a standard procedure for estimating the biomass and leaf area index in the K. candel stand, including the shorter trees, is proposed.

BAAD: a biomass and allometry database for woody plants

Understanding how plants are constructed—i.e., how key size dimensions and the amount of mass invested in different tissues varies among individuals—is essential for modeling plant growth, carbon stocks, and energy fluxes in the terrestrial biosphere. Allocation patterns can differ through ontogeny, but also among coexisting species and among species adapted to different environments. While a variety of models dealing with biomass allocation exist, we lack a synthetic understanding of the underlying processes. This is partly due to the lack of suitable data sets for validating and parameterizing models. To that end, we present the Biomass And Allometry Database (BAAD) for woody plants. The BAAD contains 259 634 measurements collected in 176 different studies, from 21 084 individuals across 678 species. Most of these data come from existing publications. However, raw data were rarely made public at the time of publication. Thus, the BAAD contains data from different studies, transformed into standard units and variable names. The transformations were achieved using a common workflow for all raw data files. Other features that distinguish the BAAD are: (i) measurements were for individual plants rather than stand averages; (ii) individuals spanning a range of sizes were measured; (iii) plants from 0.01–100 m in height were included; and (iv) biomass was estimated directly, i.e., not indirectly via allometric equations (except in very large trees where biomass was estimated from detailed sub-sampling). We included both wild and artificially grown plants. The data set contains the following size metrics: total leaf area; area of stem cross-section including sapwood, heartwood, and bark; height of plant and crown base, crown area, and surface area; and the dry mass of leaf, stem, branches, sapwood, heartwood, bark, coarse roots, and fine root tissues. We also report other properties of individuals (age, leaf size, leaf mass per area, wood density, nitrogen content of leaves and wood), as well as information about the growing environment (location, light, experimental treatment, vegetation type) where available. It is our hope that making these data available will improve our ability to understand plant growth, ecosystem dynamics, and carbon cycling in the worlds vegetation.

Self-thinning and size variation in a sugi (Cryptomeria japonica D. Don) plantation

Density and stem volume in a sugi (Cryptomeria japonica D. Don) plantation were monitored for 15 years from 1983 to 1997. The tree density decreased year after year from 5002 to 3108 ha � 1 . The time-trajectory of mean stem volume and density provided evidence in favor of the � 3/2 power law of self-thinning. The skewness of the frequency distribution of stem volume showed positive values, which means that the distribution is more or less L-shaped, and the skewness decreased with time, which indicates that smaller trees died as the stand grew. This trend is consistent with the asymmetric or one-sided competition hypothesis that self-thinning is driven by competition for light. Dead trees tended to distribute randomly with the stand growth. The relationship between standard deviation of stem volume and mean stem volume was formulated by a power function, whose exponent was significantly less than unity. This shows that coefficient of variation, ranging from 61.7 to 82.5%, decreased with increasing mean stem volume. That is, the relative size variation becomes small with stand growth. # 2002 Elsevier Science B.V. All rights reserved.

Theoretical considerations on the C-D effect in self-thinning plant populations

A model for describing the competition–density (C-D) effect in self-thinning populations was developed on the basis of the following three basic assumptions: (1) the growth of mean phytomass follows a general logistic equation; (2) final yield is independent of initial population density; and (3) there exists a functional relationship between actual and initial population densities at any given time. The resultant equation takes the same reciprocal form as the reciprocal equation of the C-D effect derived from Shinozaki–Kiras theory (i.e., the logistic theory of the C-D effect), which deals with the density effect in nonself-thinning populations. However, one of the two time-dependent coefficients is quite different in mathematical interpretation between the two reciprocal equations. The reciprocal equation for self-thinning populations is essentially the same as the reciprocal equation assumed in the derivation of the functional relationship between actual and initial population densities. The establishment of the reciprocal equation is supported by the empirical facts that the reciprocal relationship between mean phytomass and population density is discernible in not only nonself-thinning populations but also in self-thinning populations. The present model is expected to systematically interpret underlying mechanisms between the C-D effect, which is observed at a time constant among populations with various initial densities, and self-thinning, which is observed along a time continuum in a given population.

Self-thinning exponents based on the allometric model in Chinese pine (Pinus tabulaeformis Carr.) and Prince Rupprecht's larch (Larix principis-rupprechtii Mayr) stands

Abstract The allometric power relationships of mean tree height H(∝vθ) and stem volume packing d(∝vδ) to mean stem volume v were investigated in 182 Chinese pine (Pinus tabulaeformis Carr.) stands and 56 Prince Rupprechts larch (Larix principis-rupprechtii Mayr) stands. According to Wellers allometric model, the slope of the self-thinning boundary line, i.e. −1/[1−(θ+δ)], was calculated from the exponents of the allometric power relationships. The resulting slope was −1.79 for the larch and −1.72 for the pine. The self-thinning boundary lines corresponded well with the combinations of mean stem volume and density in the nine densest stands of pine and larch. The steeper slope for larch was attributed to allocation of more resources to height growth and to greater stem volume in space already occupied in the larch than in the pine, resulting in higher exponent values of θ and δ in the larch than in the pine.

Growth analysis of the self-thinning stands of Pinus densiflora Sieb. et Zucc

The competition-density (C-D) effect for self-thinning Pinus densiflora Sieb. et Zucc. stands was analyzed. The relationship between biological time τ and physical time t followed a hyperbolic curve. The coefficients At and B included in the reciprocal equation of the C-D effect in self-thinning stands (i.e. 1/w=At+B), where w and ρ, respectively, represent the mean stem volume and the realized stand density, were calculated at each time. With increasing τ, the coefficient At increased abruptly up to a maximum value, and then decreased gradually to a constant level, whereas the coefficient B decreased exponentially. The relationship between the realized stand density ρ and the initial stand density ρi was confirmed to follow the equation: 1/=1/i+, where 1/ɛ represents the asymptotic stand density at a given time. The ɛ-τ relationship was represented by the equation: =p(eμ−1), where p and μ are constants. The density in the self-thinning stands tended to converge to the same density level after a sufficient lapse of time, irrespective of the difference in initial stand density. The time-trajectory of the mean stem volume and asymptotic stand density on logarithmic coordinates moved gradually toward the self-thinning line with a slope of approximately −3/2, whereas the time-trajectory of the mean stem volume and full stand density moved initially along the self-thinning line with a slope of approximately −3/2, and then changed to move along the maximum yield line with a slope of −1.0.

Density effect, self-thinning and size distribution in Pinus densiflora Sieb. et Zucc. stands

The competition-density (C-D) effect for given times and self-thinning over time in even-aged, natural, pure stands of Pinus densiflora Sieb. et Zucc. were analyzed with the reciprocal equation of the C-D effect in self-thinning stands, and the equation describing the time-trajectory of mean stem volume and stand density. The C-D effect and self-thinning were consistently well explained by the two equations. Differences in mean stem volume and in stand density among the stands tended to merge with increasing stand age. The self-thinning line with a slope of approximately –3/2 was reached by the higher density stand prior to the medium and lower density stands. The skewness of tree height distribution showed positive values, which means that the distribution is more or less L-shaped, and in addition the skewness decreased with increasing mean tree height, which indicates that smaller trees died as the stands grew. This trend is consistent with the asymmetric (one-sided) competition hypothesis that self-thinning is driven by competition for light. The tree height distribution was analyzed using the Weibull distribution. The location parameter hmin of the Weibull distribution increased with increasing stand age, and the scale parameter a tended to increase slightly with increasing stand age. The range of the shape parameter b of the Weibull distribution corresponded to that of the skewness.

The self-thinning process in mangrove Kandelia obovata stands

The self-thinning process was monitored in crowded Kandelia obovata Sheue, Liu & Yong stands over four years. The frequency distribution of tree phytomass was an L-shape, which was kept over the experimental period. Spearman’s rank correlation coefficient for phytomass decreased as the time span of the comparison became longer, a result which indicates that the rank of phytomass changes as stands grow. Death of trees resulted from one-sided competition, i.e., death occurred in lower-rank trees. Surviving trees continued to grow. Whatever the current spatial distribution of the trees, death occurred randomly and the spatial distribution gradually became close to random as stands grew. The self-thinning exponent was 1.46, which can be regarded as evidence in favor of the 3/2 power law of self-thinning. Relative growth rate, RGR, decreased in proportion to decreasing relative mortality rate, RMR, with a proportionality constant of 1.57, which was not significantly different from the slope of the self-thinning exponent. This experimental result probably justifies the assumption that the ratio of RGR to RMR in the mean phytomass-density trajectory for any self-thinning population with different densities becomes constant as the growth stage progresses.