Diverse scaling relationships of tree height and diameter in five tree species

Background: Allometric scaling relationships are important in ecology and forestry. The metabolic scaling theory (MST) predicts a universal invariant scaling relationship for tree growth, relating height and diameter to each other.

Aims: Data on five tree species (Pinus taeda L., Pinus virginiana Mill., Liquidambar styraciflua L., Liriodendron tulipifera L., and Pinus palustris Mill.) were used to test the predictions from MST on the scaling of height–diameter and also diameter growth.

Methods: Data on tree height and diameter for five tree species from both natural forests and plantations were collected to study two types of scaling relationships: tree height–diameter and stem diameter growth. A reduced major axis of regression analysis model type II was used to determine scaling exponents from each species under different environmental conditions.

Results: No universal invariant scaling exponent was found in height–diameter and diameter growth for the five species. The scaling varied across natural forests, plantations and scales (e.g., time and number of measured trees). However, in some situations the scaling exponents failed to show significant difference with the predicted values (e.g., 2/3 or 1).

Conclusions: Diverse scaling exponents were observed for the five tree species with the scaling relationships varying with environmental settings.     

Scaling in tensile "skeletons": scale dependent length of the Achilles tendon in mammals

The Achilles tendon of a diverse group of mammals ranging from the mouse (12g) to the rhinoceros (1300kg) scales so that the tendon length varies as tendon diameter.^0-931±0.069 ( r =0.983). Tendon length scales as (body mass)^0-342±0.028, and tendon diameter scales as (body mass)^0-361±0.029. If tendon stress and strain are scale independent, the capacity of the tendon to store elastic strain energy remains proportion to body mass. If tendon stress and strain increase with body mass, energy storage may scale somewhat higher. The scaling of the Achilles tendon is consistent with its role in storing strain energy and different from that of a variety of other tensile skeletal elements which exhibit scale independent length dimensions.     

Scaling of follicular sizes in mammalian ovaries

The scaling of ovarian follicle and oocyte sizes according to body weight ( M , ranging from 0005–500 kg) has been analysed using data obtained from 22 mammalian species in nine orders. The diameters of non-growing (primordial) follicles were correlated significantly with body weight, the relationship being described by the allometric formula y = 0028 M ^0.10. The mean size at which growing follicles began to accumulate extracellular fluid was approximately the same in all species, 0–3 mm diameter. Graafian follicle sizes varied allometrically with body weight as a result of differences in the volumes of follicular fluid rather than those of oocytes, which were relatively similar in eutherian mammals. The statistical significance of the correlation between Graafian and body sizes was increased when the dimensions for an ovulatory quota of follicles were combined because follicles in polyovulating species were disproportionately small. The total Graafian surface areas and volumes were then predicted from body weight by 58–4 M ^0.65 and 18–5 M ^1.06, respectively. Follicular dimensions in the three species of primates were significantly greater than predicted by the allometric relationship. The exponents of these relationships show that the total volume of a set of preovulatory follicles varies approximately isometrically with body weight and, therefore, with the presumptive hormone distribution volume ( M ^1.0). The hypoallometric relationship of follicular surface area demonstrates that, during the course of the evolution of body size, the surface area for secretion has not increased to match the dilution of hormones in the body pool.     

On linking multiyear biometric measurements of tree growth with eddy covariance-based net ecosystem production

Annual measurements of the diameter growth and litter fall of trees began in 1998 using a 1.0 ha permanent plot beneath a flux tower at the Takayama flux site, central Japan. This opened up an opportunity for studies that compare the interannual variability in tree growth with eddy covariance-based net ecosystem production (NEP). A possible link between multiyear biometric-based net primary production (NPP) and eddy covariance-based NEP was investigated to determine the contribution of autotrophic production and heterotrophic respiration (HR) to the interannual variability of NEP in deciduous forest ecosystems. We also defined the NEP^* as the measurable organic matter stored in an ecosystem during the interval in which soil respiration (SR) measurements were taken. The difference of biometric-based NEP^* from eddy covariance-based NEP within a given year varied between 55% and 105%. Woody tissue NPP (stems and coarse roots) varied markedly from 0.88 to 1.96 Mg C ha⁻¹ yr⁻¹ during the 8-year study period (1999–2006). Annual woody tissue NPP was positively correlated with eddy covariance-based NEP ( r ²=0.52, P <0.05). However, neither foliage NPP ( r ²=0.03) nor HR ( r ²=0.06) were correlated with eddy covariance-based NEP. Therefore, it was hypothesized that interannual variability in the ecosystem carbon exchange was directly responsible for much of the interannual variation in autotrophic production, especially carbon accumulation in the woody components of the ecosystem. Moreover, similar interannual variations of biometric-based NEP^* and eddy covariance-based NEP with small variations in SR and foliage NPP suggest a constant net accumulation of carbon in nonliving pools at the Takayama site.     

Distribution of transition metal ions in multiple forms of Methanosarcina hydrogenase

There were significant levels of in vitro hydrogenase activity in Methanosarcina strains. The multiple forms of hydrogenase were observed in cell free extracts of cells grown on methanol. Strains having poor growth on H₂ : CO₂ had four forms while strains having normal growth on all substrates contained two forms of hydrogenase. These multiple forms differ in their charges as well as in their composition of transition metal ions. The strain having normal growth showed higher incorporation of ⁶³Ni²⁺ and ⁶⁵Zn²⁺. Both hydrogenases, A and D, of strain P₃ had methylviologen and F₄₂₀-reducing activity and contained Zn²⁺ and Co²⁺ respectively. Hydrogenases A and D of strains P₁ and P₄ also had similar characteristics whereas hydrogenases B and C had only methylviologen reducing activity.     

Testing the Metabolic Scaling Theory of tree growth

1.  Metabolic Scaling Theory (MST) predicts a 'universal scaling law' of tree growth. Proponents claim that MST has strong empirical support: the size-dependent growth curves of 40 out of 45 species in a Costa Rican forest have scaling exponents indistinguishable from the MST prediction.
2.  Here, we show that the Costa Rican study has been misinterpreted. Using Standardized Major Axis (SMA) line-fitting to estimate scaling exponents, we find that four out of five species represented by more than 100 stems have scaling exponents that deviate significantly from the MST prediction. On the other hand, sample sizes were too small to make strong inferences in the cases of 33 species represented by fewer than 50 stems.
3.  Recently, it has been argued that MST is useful for predicting average scaling exponents, even if individual species do not conform to the theory. We find that the mean scaling exponent of the Costa Rican trees is greater than predicted (across-species mean  =  0.44), and hypothesize that scaling exponents in natural forests will generally be greater than predicted, because the theory fails to model asymmetric competition for light.
4.   Synthesis . We highlight shortcomings in the interpretation of data used in support of a key MST prediction. We recommend that future research into biological scaling should compare the merits of alternative models rather than focusing attention on tests of a single theory.     

Wing-bone length allometry in birds

A comparative analysis using both independent contrasts (CAIC) and a species level analysis was used to investigate the allometric scaling of avian wing-bone lengths. Total arm ( ta =humerus+ulna+manus) scaled with positive allometry as body mass ( M )^0.37–0.39. Similarly, and in accordance with previous studies, wing-span ( b ) was positively allometric, but CAIC suggested a lower allometric exponent ( M ^0.35) than found using species as independent data points ( M ^0.39). Contrary to previous studies, individual wing-bones appear to scale with similar exponents against M and scale isometrically with ta . In addition to a general trend for larger birds to have longer wings, wing-bones and ta , their ta was a larger proportion of their b . A detailed study of primary feather length and elbow joint angle across a wide range of bird species and bird size, however, is required before a conclusive explanation for this increase in ta relative to b in larger birds can be established. Scaling equations are presented that can be used to predict M , ta and b from individual wing-bone lengths, which may be of use to palaeontologists wishing to reconstruct whole animals from single bones.     

Differing effects of suspended sediments on the performance of native and exotic Daphnia

1. Although large cladocerans are usually uncommon in large rivers, Daphnia lumholtzi (an exotic species in North America) is widespread and occasionally abundant. We collected zooplankton on the Illinois River (Illinois, U.S.A.) in 1995 and 1996 and found that the peak density of D. lumholtzi (25 L⁻¹) typically exceeded that of all native species combined. Maximum density occurred during warm periods (up to 27 °C) when concentrations of inorganic suspended sediments were high (>50 mg L⁻¹).
2. Using a life table experiment, we examined the effects of variation in suspended sediment (0 and 80 mg L⁻¹) and food (10⁴ and 10⁵ Ankistrodesmus cells mL⁻¹) on fitness of D. lumholtzi and the native Daphnia parvula. Daphnia lumholtzi had greater survivorship than D. parvula in most treatments and higher life-time fertility than D. parvula in all treatments. Both species achieved their fastest intrinsic rates of growth in treatments with high food, but their responses to suspended solids differed. The growth rate of D. lumholtzi in high food was slightly increased by higher turbidity, whereas that of D. parvula was depressed.
3. Results suggest that the ability of D. lumholtzi to tolerate suspended solids is an important factor contributing to its success in invading North American rivers.     

In vitro and in vivo regulation of chloroplast glyceraldehydes-3-phosphate dehydrogenase isozymes from Chenopodium rubrum. I. Purification and properties of isozymes

Chloroplast glyceraldehyde-3-phosphate dehydrogenase (GPD, EC 1.2.1.13) was purified from leaves of Chenopodium rubrum L. Aggregated (≥ 10⁶) and disaggregated (165 × 10³) molecular weight forms were obtained by gel filtration in the presence of NAD⁺ and NADP⁺, respectively. The disaggregated enzyme was separated into two isozymes by inverse ammonium sulphate gradient solubilization: "NADP-GPD I" was homotetrameric (subunit molecular weight 39 × 10³); "NADP-GPD II" was heterotetrameric (subunit molecular weights 39 × 10³ and 43 × 10³). Isoelectric focusing of the isozymes, both aggregated and disaggregated, revealed two isoelectric forms in each case, at 4.3 and 7.7. Chloroplast GPD was "NADP-suppressed" in crude extracts due to partial oxidation, incubation with dithioerythritol restored full activity.     

Food consumption and growth of two piscivorous fishes, the mandarin fish and the Chinese snakehead

Rates of maximum food consumption and growth were determined for immature mandarin fish Siniperca chuatsi (47·2—540·2 g) and Chinese snakehead Channa argus (45·0—546·2 g) at 10, 15, 20, 25, 30 and 35) C. The relationship between maximum rate of food consumption ( C max), body weight ( W ) and temperature ( T ) was described by the multiple regression equations: In C max=−4·880+0·597 In W +0·284 T −0·0048 T ² for the mandarin fish, and In C max=−6·718+ 0·522 In W +0·440 T −0·0077 T ² for the Chinese snakehead. The optimum temperature for consumption was 29·6) C for the mandarin fish and 28·6) C for the Chinese snakehead. The relationship between growth rate ( G ), body weight and temperature was ln( G +0·25)=−0·439−0·500 ln W +0·270 T −0·0046 T ² for the mandarin fish, and ln( G +0·25)=−6·150+ (0·175−0·026 T ) ln W +0·571 T −0·0078 T ² for the Chinese snakehead. The weight exponent in the growth–weight relationship was −0·83 for the mandarin fish, but decreased with increasing temperature for the Chinese snakehead. The optimum temperature for growth was 29·3) C for the mandarin fish, but tended to decrease with increasing weight for the Chinese snakehead, being 30·3) C for a 45-g fish, and 26·1°C for a 550-g fish.     

Estimating species richness at large spatial scales using data from small discrete plots

Estimating species richness in large biomes is a central challenge in ecology and conservation biology. However, accurate census data is often available only from small discrete plots distributed within the biome. Using tree species richness data collected from 48 plots (0.25 ha each) widely distributed through 60 000 km² in the rainforests of the Western Ghats of southern India, we test the application of a proposed method for estimating species richness at large scales from measured species commonalities between pairs of censused plots. We show that the method allows extrapolation of species richness from a scale of 0.25 ha plots to that of the entire biome, or 10⁵ km².     

Bacterivory by the ciliate Euplotes in different states of hunger

Abstract: The feeding of the marine ciliate Euplotes mutabilis was studied using bacteria ( Vibrio natriegens ) doubly labelled with ³H-thymidine and ¹⁴C-leucine. In the presence of abundant bacteria (30 × 10⁶ bacteria ml⁻¹), an average Euplotes cell (initially without food vacuoles) with a protein content of 12 ng consumed 16 × 10³ bacteria in the first hour and 27 × 10³ bacteria over four hours, accumulating about 60% of the bacterial protein into ciliate macromolecules. Euplotes which had been starved or under-fed to reduce cell protein biomass to 7 or 9 ng consumed significantly fewer bacteria, but the gross growth efficiency for protein did not change. The rate of consumption of bacteria by large Euplotes of protein content 15 ng was initially less than that of 12 ng cells, and it decreased markedly before the end of a 4-hour experiment. Recently divided cells ingested bacteria rapidly, but showed a reduced gross growth efficiency of about 40%. At low bacterial concentrations (6 × 10⁶ bacteria ml⁻¹) the rates of ingestion were markedly reduced to between     and     of maximal levels; the smallest cells could not sustain feeding activity at the low prey concentration and gross growth efficiency fell from 43 to 20% during a 4-hour experiment. The strategy adopted by Euplotes in response to local fluctuations in food supply involves rapid consumption with high growth efficiency in times of plenty, but slow shrinkage without cell division to survive in times of shortage.     

Microbial colonization of an in vitro model of a tissue engineered human skin equivalent – a novel approach

This was a preliminary investigation to define the conditions of colonization of a human skin equivalent (SE) model with cutaneous microorganisms. SEs of 24 mm diameter were constructed with a dermal matrix of fibrin containing fibroblasts and a stratified epidermis. Microbial colonization of the SEs was carried out in a dry environment, comparable to ' in vivo ' skin, using a blotting technique to remove inoculation fluid. The microbial communities were sampled by scrub washing and viable cells enumerated on selective growth medium. Staphylococcus epidermidis , Propionibacterium acnes and Malassezia furfur (human skin commensals) and Staphylococcus aureus (transient pathogen) were colonized at inoculum densities of 10²–10⁶ CFU SE⁻¹ on the surface of replicate SEs. Growth of all species was supported for upto 72–120 h, with recovery densities of between 10⁴–10⁹ CFU SE⁻¹. A novel, real-time growth monitoring method was also developed, using S. aureus containing a lux cassette. Light output increased from 20 to 95 h, and colonization increased from 10² to 10⁸ CFU SE⁻¹, as confirmed by conventional recovery. Thus, the SE model has potential to investigate interactions between resident and transient microbial communities with themselves and their habitat, and for testing treatments to control pathogen colonization of human skin.     

模拟氮沉降对北京东灵山辽东栎林树木生长的影响

传统的元素限制模型认为氮是温带森林生长的限制元素, 不过该结论更多是从地上生物量以及群落水平进行阐述, 忽视了不同物种以及不同径级树木对外源氮的响应差异。辽东栎(Quercus wutaishanica)林是华北地区常见的森林类型, 该研究以北京东灵山辽东栎林为研究对象, 通过设置3个氮添加水平的实验, 即对照CK (0 kg·hm ^-2·a ^-1), N50 (50 kg·hm ^-2·a ^-1)和N100 (100 kg·hm ^-2·a ^-1), 模拟氮沉降对群落和物种水平以及不同径级树木生长的影响。经过7年氮添加, 实验结果显示: 物种水平上, 氮添加明显促进了优势树种辽东栎的生长; 群落水平上, 树木生长随氮浓度增加有不断上升趋势, 但统计学差异不显著; 氮添加显著抑制了辽东栎以及群落内小径级(3-10 cm)树木生长, 中(10-20 cm)、大径级(>20 cm)树木生长随氮沉降水平增加呈上升趋势, 但统计学差异不显著。表明氮是辽东栎以及温带森林树木生长的限制元素; 不同径级的辽东栎和群落内其他植物对氮添加响应不一致, 氮添加抑制了小径级树木生长, 中、大径级树木生长对氮添加响应不明显。     

Species-specific allometric scaling under self-thinning: evidence from long-term plots in forest stands

Experimental plots covering a 120 years' observation period in unthinned, even-aged pure stands of common beech (Fagus sylvatica), Norway spruce (Picea abies), Scots pine (Pinus sylvestris), and common oak (Quercus Petraea) are used to scrutinize Reineke's (1933) empirically derived stand density rule [see text], N=tree number per unit area, [see text]=mean stem diameter), Yoda's (1963) self-thinning law based on Euclidian geometry ([see text] [see text]=mean biomass per tree), and basic assumptions of West, Brown and Enquist's (1997, 1999) fractal scaling rules ([see text] [see text] w=biomass per tree, d=stem diameter). RMA and OLS regression provides observed allometric exponents, which are tested against the exponents, expected by the considered rules. Hope for a consistent scaling law fades away, as observed exponents significantly correspond with the considered rules only in a minority of cases: (1) exponent r of [see text] varies around Reineke's constant -1.605, but is significantly different from r=-2, supposed by Euclidian or fractal scaling, (2) Exponent c of the self-thinning line [see text] roams roughly about the Euclidian scaling constant -3/2, (3) Exponent a of [see text] tends to follow fractal scaling 8/3. The unique dataset's evaluation displays that (4) scaling exponents and their oscillation are species-specific, (5) Euclidian scaling of one relation and fractal scaling of another are coupled, depending on species. Ecological implications of the results in respect to self-tolerance (common oak>Norway spruce>Scots pine>common beech) and efficiency of space occupation (common beech>Scots pine>Norway spruce>common oak) are stressed and severe consequences for assessing, regulating and scheduling stand density are discussed.     

Effects of egg composition and prey density on the larval growth and survival of lake whitefish (Coregonus clupeaformis Mitchill)

Eggs were collected from two stocks of lake whitefish, Coregonus clupeaformis , in Lakes Michigan and Huron to assess the effect of egg composition and prey density on larval growth and survival. Egg composition parameters including wet weight (mg egg⁻¹), dry weight (mg egg⁻¹), percent water, total caloric content (cal egg⁻¹), caloric density (cal egg⁻¹), percent lipid content, and total lipidcontent (mg egg⁻¹) were measured. Fish hatched from six parental females in each stock were fed one of four rations (0, 18, 24, 50 brine shrimp larva⁻¹ day⁻¹) after yolk sac absorption. Length at hatch, endogenous growth, exogenous growth, and survival were measured during a 42-day laboratory experiment. Length at hatch of larvae was positively related to egg caloric content ( r ²=0.780). Endogenous growth for lake whitefish larvae was positively related to percent lipid content ( r ²=0.896) and total egg lipid content ( r ²=0.876) of parental females. Exogenous growth and survival of larval lake whitefish was positively related to prey availability. Larval fish growth was accurately modelled ( r ²=0.973) as a function of prey abundance using a threshold-corrected hyperbolic equation. These results indicate that both egg composition and prey availability have the potential to influence the growth and survival dynamics of larval lake whitefish significantly.     

Scaling of rectal gland mass in the European lesser-spotted dogfish

In the European lesser-spotted dogfish Scyliorhinus canicula , rectal gland mass in mg ( M _Rg) followed the allometric relationship: M _Rg = 1·15 M ^0·68, where M is body mass (g). The concept of allometric scaling is an important consideration in studies investigating the function of osmoregulatory organs.     

Effects of aluminium on growth and kinetics of K+(86Rb) uptake in two cultivars of wheat (Triticum aestivum) with different sensitivity to aluminium

Two cultivars of wheat (Triticum aestivum L. cvs Kadett and WW 20299) were grown for 9 days with 20% relative increase in nutrient supply per day at pH 4.1. Aluminium at 50 μ M retarded the growth of roots more than that of shoots in both cultivars, thus decreasing the root/shoot ratio. The inhibition was largest in WW 20299. With long term Al treatment (9 days), K_m for K⁺(⁸⁶Rb) influx increased five times in both cultivars and V_max decreased in WW 20299. Efflux of K⁺(⁸⁶Rb) was little affected. When the roots were treated with aluminium for two days, only relative growth rate of roots was retarded, while growth of shoots was unaffected and influx of K⁺(⁸⁶Rb) adjusted to the actual K⁺ demand of the plants. It is concluded that the effects of aluminium on K⁺ uptake in these wheat cultivars are not primary factors contributing to aluminium sensitivity. However, in soil with Al the demand for a comparatively high concentration of K⁺ to maintain an adequate K⁺ uptake rate, in combination with a slow growth rate of the roots, may secondarily lead to K⁺ deficiency in the plants.     

Longevity of the freshwater anostracan Streptocephalus mackini (Crustacean: Anostraca) in relation to food (Chlorella vulgaris) concentration

SUMMARY 1. Temporary ponds are inhabited by a variety of invertebrates, of which anostracans are an important group. We studied the lifetables of male and female anostracan Streptocephalus mackini at 3 algal concentrations (0.5 × 10⁶, 1.0 × 10⁶ and 1.5 × 10⁶ cells mL⁻¹).
2. Regardless of sex, S. mackini showed better survivorship at lower food levels. The longest average lifespan observed was 85 ± 2 days for males fed Chlorella at 0.5 × 10⁶ cells mL⁻¹.
3. Both net reproductive rate and generation time decreased with increasing food level. The highest net reproductive rate was about 120 cysts per female. The longest generation time of about 40 days, observed at 0.5 × 10⁶ cells mL⁻¹, was more than three times that at 1.5 × 10⁶ cells mL⁻¹.
4. The rate of population increase ( r ) was nearly the same (0.31 ± 0.06) at high (1.5 × 10⁶ cells mL⁻¹) and intermediate (1.0 × 10⁶ cells mL⁻¹) food levels. The r -value at low food level (0.5 × 10⁶ cells mL⁻¹ of Chlorella ) was 0.20 ± 0.01 per day.     

Allometry of the limb bones of mammals from shrews (Sorex) to elephant (Loxodonta)

Measurements have been made of the principal leg bones of 37 species representing almost the full range of sizes of terrestrial mammals. The lengths of corresponding bones tend to be proportional to (body mass)^0·35 and the diameters to (body mass)^0·36, except in the family Bovidae in which the exponents for length are much nearer the value of 0·25 predicted by McMahon's (1973) theory of elastic similarity. Comparisons are made between mammals of similar size belonging to different orders.