Trunk Biomass Research Articles

Allometric relationships for branch and tree woody biomass of Maritime pine ( Pinus pinaster Aı̈t.)

Modelling biomass repartition in a tree is either done using theories regarding carbon transfer and allocation or through empirical repartition coefficients. The latter can be derived from the study of the allometric relationships inside a tree, which reflect the equilibrium between tree structure and biomass. In order to quantify the biomasses of the main aerial compartments (needles, stem wood, stem bark, branch wood and buds) of a Maritime pine tree ( Pinus pinaster Aı̈t.) and to assess their relationships with tree structure, we undertook some destructive measurements of architecture and biomass. The study of leaf area was presented in a specific paper [Porté et al., Ann. For. Sci. 57 (1) (2000) 73], and the present paper is dealing with the woody compartments (branch wood, stem bark and wood). We collected biomass samples on thirty 5-year-old, sixteen 26-year-old and ten 32-year-old Maritime pines. Allometric equations were developed per site to estimate branch wood biomass. It depended only on the branch basal diameter and the models were very satisfying. Using these equations, we estimated the total branch wood biomass of each sampled tree. A single relationship for all sites was found to model crown or trunk biomass. A power function of tree diameter at breast height (DBH) and the inverse of tree age was fitted to the branch wood data. A power function of DBH and tree age was used for the stem wood and bark models, which takes into account the differences in vitality with different ages. All models performed quite well. Input variables were easy to measure so that the models could be applied to estimate the aerial biomass of a whole stand, per compartment, over a 20-year-long period. The allometric relationships presented here can be derived to be used as biomass repartition laws, for a 5–30-year-old Maritime pine stand in humid Lande.

�valuation de la biomasse arbor�e et arbustive dans une s�quence de d�gradation de la suberaie � Cytise de Kroumirie (Tunisie)

Evaluation of the overstorey and understorey biomasses in a damaging sequence of cytisus cork oak forest in Kroumirie (Tunisia). The aerial and underground biomasses of the overstorey and understorey have been studied in a damaging sequence of cytisus cork oak stands in Kroumirie region. Measurements of biomass and dendrometric parameters on twelve sampled trees have been realized in different plots, with variable damage stages. The allometric relationships obtained allowed to dete ct the best predictive variables of partial biomasses at individual and stand levels. At individual level, branch girth at stem insert ion and diameter at breast height (DBH) are highly predictive parameters. The aerial biomass of a tree cork oak of medium size (DBH = 20 cm) represents 81.5% of the total tree biomass against 18.5% for the roots. The bole contains 57% of the aboveground biomass with 44% in the wood and 13% in the cork. 43% within the crown are subdivided into branch wood (23%), branch cork (12%), twigs and leaves (4% each). Moreover, the percentage of cork in the trunk biomass decreases with increasing DBH. At stan d

Long-term productivity of a Grevillea robusta-based overstorey agroforestry system in semi-arid Kenya : II. Crop growth and system performance

Maize and cowpea were grown as sole stands or in agroforestry systems containing grevillea trees ( Grevillea robusta A. Cunn.). Crop and system performance were examined over a 4.5-year-period (nine growing seasons) commencing in October 1991; failure of the rains caused the loss of one cropping season. A rotation of cowpea ( Vigna unguiculata L. Walp.) and maize ( Zea mays L.) was grown during the first five seasons after planting the trees, while maize was grown continuously during the final four seasons. Sole maize was also grown under spectrally neutral shade netting which reduced incident radiation by 25, 50 or 75% to establish the relative importance of shade and below-ground competition for water and nutrients in determining the performance of understorey crops. The above-ground biomass and grain yield of understorey crops were not significantly affected by the presence of grevillea during the first four seasons, but were greatly reduced in subsequent seasons as the trees became increasingly dominant; maize yields reached 50% of the sole crop values only once during the final four seasons, when rainfall was unusually high. The hypothesis that competition for water was the primary limiting factor for understorey crops was supported by the observation that above-ground biomass and grain yield were greater in the shade net treatments than in agroforestry maize, demonstrating that shade was not solely responsible for the substantial yield losses in the latter treatment. Performance ratios (ratio of values for the agroforestry system relative to sole stands) for total above-ground and trunk biomass in grevillea were initially low, reflecting the impact of competition with associated crops during tree establishment, but increased to unity within 2.5 years. Performance ratios for the understorey crops exhibited the reverse trend, initially being close to unity but approaching zero for three of the final four seasons. Performance ratios were never close to unity for both trees and crops during the same season, indicating that there was always competition for available resources irrespective of crop species or tree size. The implications for agroforestry system design and future research are discussed.

Long-term productivity of a Grevillea robusta-based overstorey agroforestry system in semi-arid Kenya: I. Tree growth

The work reported here formed part of a multidisciplinary project to examine the changing tree/crop interactions, expressed in terms of resource capture, tree and crop growth and system performance, that occur as the trees in semi-arid agroforestry systems establish and mature. Grevillea robusta (A. Cunn.; grevillea) trees were grown in a dispersed planting arrangement, either as sole stands or in combination with cowpea ( Vigna unguiculata L.) or maize ( Zea mays L.). Allometric approaches were used to monitor leaf area and leaf, branch and trunk biomass over a 4.5-year period. Seasonal and annual growth increments and the corresponding mean daily growth rates were calculated; crop growth, development and yield were also determined over nine growing seasons. Tree height, leaf area and trunk and branch biomass were reduced in the agroforestry treatment (CTd) during the first 600 days after planting as a result of competition with the associated crops. Tree height subsequently increased more rapidly in the agroforestry treatment (CTd) and regained parity with the sole grevillea treatment (Td) by ca. 820 days after planting. However, although seasonal and annual biomass increments were comparable in both treatments once the trees became the dominant component of the system, above-ground biomass in CTd grevillea never recovered fully to Td values during the observation period; trunk volume and biomass were consistently lower in CTd than in Td grevillea, reducing their economic value. Tree growth continued throughout the dry season, sometimes at rates similar to or greater than observed during the cropping seasons, indicating that the trees were able to utilise residual soil moisture or deep reserves within the profile. This finding is discussed in relation to recent interpretations of niche separation in savanna vegetation. The factors responsible for the observed reductions in tree growth in the agroforestry system are examined; effects on crop yields and system performance are considered in Part II.

Productivity, microclimate and water use in Grevillea robusta-based agroforestry systems on hillslopes in semi-arid Kenya

This paper describes a multi-disciplinary project to examine the changing interactions between trees and crops as the trees in semi-arid agroforestry systems establish and mature; the project is one of the most detailed and highly instrumented long-term studies of tree and crop growth, system performance, resource capture, hydrology and microclimate ever carried out within an agroforestry context. Its primary objective was to compile a comprehensive experimental database to improve the mechanistic understanding of tree/crop interactions and support the development and validation of process-based simulation models describing resource capture and tree and crop growth in semi-arid agroforestry systems. Grevillea robusta A. Cunn. (grevillea) trees were grown as mono-cultures or in mixtures with cowpea ( Vigna unguiculata L.) or maize ( Zea mays L.) over a 68-month period. Allometric approaches were used to determine seasonal and annual growth increments for leaf area and leaf, branch and trunk biomass in grevillea. Crop performance was examined during each growing season, while the spatial distribution of tree and crop roots was established during the latter stages of the experiment using coring and mini-rhizotron approaches. Detailed hydrological studies examined effects on the soil water balance and its components (precipitation, interception, runoff and soil moisture status); equivalent measurements of spatial and temporal variation in microclimatic conditions allowed the mechanistic basis for beneficial and detrimental effects on understorey crops and the influence of proximity to trees on crop performance to be examined. Transpiration by grevillea and water movement through lateral and tap roots were measured using sap flow methodology, and light interception by the tree and crop canopies was routinely determined. This multi-disciplinary study has provided a detailed understanding of the changing patterns of resource capture by trees and crops as agroforestry systems mature. This paper provides an overview of the underlying rationale, experimental design and core measurements, outlines key results and conclusions, and draws the attention of readers to further papers providing more detailed consideration of specific aspects of the study.

Allometric estimation of above-ground biomass and leaf area in managed Grevillea robusta agroforestry systems.

Non-destructive methods for determining the biomass and leaf area of individual trees throughout their growing cycle are an essential tool in agroforestry research, but must be capable of providing reliable estimates despite the influence that management strategies such as pruning may have on tree form. In the present study, allometric methods involving measurements of the diameter of all branches provided reliable estimates of canopy leaf area and biomass for grevillea trees (Grevillea robusta A. Cunn.; Proteaceae) grown as poles, but proved unsuitable for routine measurements because of their time-consuming nature. An alternative, less laborious method based on measurements of trunk cross-sectional area immediately below the first branch of the canopy provided satisfactory allometric estimates of leaf area and canopy biomass. Trunk biomass was determined from measurements of tree height and diameter at breast height using established methodology based on the assumption that trunk volume may be calculated using a quadratic paraboloid model; biomass was determined as the product of trunk volume and the specific gravity of the wood. The theoretical basis, development and validation of allometric methods for estimating tree growth are discussed and their wider applicability to other agroforestry systems is assessed.

The potential of synthetic aperture radar (SAR) for quantifying the biomass of Australia's woodlands.

The potential of Synthetic Aperture Radar (SAR) for estimating the above ground and component biomass of woodlands in Australia is demonstrated using two case studies. Case Study 1 (In,june; central Queensland) shows that JERS-1 SAR L HH data can be related more to the trunk than the leaf and branch biomass of woodlands. A strong relationship between L HH and above ground biomass is obtained when low biomass pasture sites are included. Case Study I1 (Talwood, southern Queensland) determines that L and P band data can be related both to trunk and branch biomass, due to the similarity in the orientation and size of these scattering elements, and also to total above ground biomass. Saturation of the C. L and P band data occurred at approximately 20-30 Mglha; 60-80 Mglha and 80-100 Mglha. These preliminary results indicate that data from SAR are useful for quantifying changes in carbon stocks resulting from land use change in Australia's woodlands and for applications in rangeland assessment and management. Key words: remote sensing, biomass, woodlands

Do Logs from Tropical Rain Forests Contain More Plant Nutrients than Logs from Temperate Forests

This literature review is based on data on amounts of plant nutrients in trunk biomass, other biomass, litter, humus and soil in tropical rain forest ecosystems obtained from 24 publications. These data were compared with corresponding figures for 29 randomly selected temperate coniferous stands and 14 randomly selected temperate deciduous forests stands. No statistically significant difference was found between tropical rain forests and temperate forests in terms of concentrations of phosphorus in trunks or in the trunk proportion of the total amount of phosphorus in the ecosystem. There are statistical differences between lowland tropical rain forests and temperate coniferous and deciduous forests in concentrations of nitrogen and magnesium in trunks, but for potassium and calcium only between lowland tropical rain forests and temperate coniferous forests. However, when the amounts of plant nutrients in trunks are calculated in percentages of the amounts in the ecosystems, statistical differences are found in amounts of nitrogen and magnesium only between lowland tropical rain forests and temperate coniferous forests.

Evaluation of approaches to estimating aboveground biomass in Southern pine forests using SIR-C data

A study was performed to evaluate various techniques for estimating aboveground, woody plant biomass in pine stands found in the southeastern United States, using C- and L- band multiple polarization radar imagery collected by the Shuttle Imaging Radar-C (SIR-C) system. The biomass levels present in the test stands ranged between 0.0 and, 44.5 kg m −2. Two SIR-C data sets were used: one collected in April, 1994, when the soil conditions were very wet and the canopy was slightly wet from dew and a second collected in October, 1994, when the soils and canopy were dry. During the October mission, pine needles were completely flushed and the foliar biomass was twice as great in the forest stands as in April. Four methods were evaluated to estimate total biomass: one including a straight multiple linear correlation between total biomass and the various SIR-C channels; another including a ratio of the L-band HV/C-band HV channels; and two others requiring multiple steps, where linear regression equations for different stand components (height, basal area, and crown or branch biomass) were used as the basis for estimating total biomass. It was shown that the data collected in October (dry soil conditions) were better for estimation of biomass than the data collected in April (wet soil conditions). Overall, a multistep approach resulted in the lowest root mean square (RMS) errors (5.91 kg m −2) when biomass levels were <20 kg m −2. For all biomass levels, the simple regression technique resulted in the lowest RMS errors (8.1 kg m −2). The multiple-step approaches have the additional advantage of being able to provide estimates of different components of stand structure and biomass, such as average tree height, basal area, branch biomass, canopy biomass, trunk biomass, and foliage biomass. The LHV channel is the critical element in all the biomass equations, as would be expected from the body of literature. The addition of other channels—generally, CHV or CHH—significantly improves biomass estimates, whether as a ratio or as additional terms in a regression equation.

Estimation of forest biophysical characteristics in Northern Michigan with SIR-C/X-SAR

A three-step process is presented for estimation of forest biophysical properties from orbital polarimetric SAR data. Simple direct retrieval of total aboveground biomass is shown to be ill-posed unless the effects of forest structure are explicitly taken into account. The process first involves classification by (1) using SAR data to classify terrain on the basis of structural categories or (2) a priori classification of vegetation type on some other basis. Next, polarimetric SAR data at L- and C-bands are used to estimate basal area, height and dry crown biomass for forested areas. The estimation algorithms are empirically determined and are specific to each structural class. The last step uses a simple biophysical model to combine the estimates of basal area and height with ancillary information on trunk taper factor and wood density to estimate trunk biomass. Total biomass is estimated as the sum of crown and trunk biomass. The methodology is tested using SIR-C data obtained from the Raco Supersite in Northern Michigan on Apr. 15, 1994. This site is located at the ecotone between the boreal forest and northern temperate forests, and includes forest communities common to both. The results show that for the forest communities examined, biophysical attributes can be estimated with relatively small rms errors: (1) height (0-23 m) with rms error of 2.4 m, (2) basal area (0-72 m/sup 2//ha) with rms error of 3.5 m/sup 2//ha, (3) dry trunk biomass (0-19 kg/m/sup 2/) with rms error of 1.1 kg/m/sup 2/, (4) dry crown biomass (0-6 kg/m/sup 2/) with rms error of 0.5 kg/m/sup 2/, and (5) total aboveground biomass (0-25 kg/m/sup 2/) with rms error of 1.4 kg/m/sup 2/. The addition of X-SAR data to SIR-C was found to yield substantial further improvement in estimates of crown biomass in particular. However, due to a small sample size resulting from antenna misalignment between SIR-C and X-SAR, the statistical significance of this improvement cannot be reliably established until further data are analyzed. Finally, the results reported are for a small subset of the data acquired by SIR-C/X-SAR.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The effects of changes in forest biomass on radar backscatter from tree canopies

Abstract We validated a canopy backscatter model for loblolly pine forest stands at the Duke Forest, North Carolina, by comparing the observed and modelled SAR backscatter from the stands. Given the SAR backscatter data calibration uncertainty, the model made good predictions of C-HH, C-HV, L-HH, L-HV, L-VV, P-HH, and P-HV backscatter for most of 25 stands studied. The model overestimated C-VV backscatter for several stands, and largely overestimated P-VV backscatter for most of the stands. Using the collected SAR backscatter and ground data, and the backscatter model, we studied the influences of changes in biomass on SAR backscatter as a function of radar frequency and polarization, and evaluated the feasibility of deriving the biomass from the backscatter. This study showed that C-HH, C-HV, C-VV, L-VV, and P-VV SAR backscatter may be insensitive to the biomass change. L-HH, L-HV, P-HH, and P-HV SAR backscatter changed more than 5dB as the biomass varied. This study also showed that the L-HH and P-HH backscatter or L-HV and P-H V backscatter may be used to develop algorithms to retrieve trunk biomass or canopy biomass of the loblolly pine forests.

Calibration and modelling of MAESTRO 1 polarimetric SAR data of a forest area in Les Landes, France

Abstract Abstract. The results of an analysis of polarimetric P, Land C-band SAR data from the JPL AIRSAR of a forest area of maritime pine in Les Landes, southwest France, are described and discussed. The data were acquired in connection with the MAESTRO I Campaign organized by ESA and JRC/lspra. Cross-talk and channel imbalance distortions are removed in a calibration process using the SAR data itself and trihedral corner reflectors positioned at the scene. Two calibration methods have been implemented and compared: the iterative Klein algorithm and the non-iterative Quegan algorithm. Quegan's method shows the largest reduction of the cross-talk, and the most stable and easily interpreted results. Also, absolute calibration using the integral method has been performed. The results presented show that P band (and to some extent L band) is very sensitive to trunk biomass using single-polarization radar data, at least at the incidence angles in the range from 38° to 52°, whereas C band is less sensitive. A...

Carbohydrate requirements for dark respiration by peach vegetative organs.

The specific respiration rate at 20 degrees C (R(20)) of peach leaves and stems declined rapidly from a high value in the early spring (22.5 nmol CO(2) g(dw) (-1) s(-1)) to relatively constant rates by July (3.1 nmol CO(2) g(dw) (-1) s(-1)). Leaf R(20) declined more rapidly than current-year stem R(20), but leaf and current-year stem R(20)s were similar by July. The R(20) of current-year stems in July was approximately 2.5 times greater than that of one-year-old stems (1.3 nmol CO(2) g(dw) (-1) s(-1)), and about 30 times greater than that of the trunk R(20) (0.1 nmol CO(2) g(dw) (-1) s(-1)). The Q(10)s of leaves and stems were approximately 2 for a temperature increase between 20 and 30. The Q(10)s above 30 were 2.03 for leaves but only 1.61 for stems. Leaves and current-year stems accounted for 2 and 17% of the aboveground vegetative biomass in April and August, respectively, but accounted for 59-80% of total daily (24 h) respiration. Although trunk biomass accounted for 91 and 77% of aboveground vegetative biomass, in April and August, respectively, trunk respiration accounted for only 8-15% of daily aboveground respiration. Before harvest, during a period when fruit growth was source-limited, daily fruit respiration exceeded respiration by all aboveground vegetative organs.

The Effect of Palm Age and Planting Density on the Partitioning of Assimilates in Oil Palm (Elaeis guineensis)

SUMMARYYield and growth records from an oil palm planting density experiment, comparing 56, 110, 148 and 186 palms ha−1, and a progeny experiment, planted at 115 and 143 palms ha−1, were used to estimate the partitioning of assimilates into those used for structural dry matter (DM) production, and those used for growth and maintenance respiration.Gross photosynthetic assimilation (A) for closed canopies was estimated from absorbed photosynthetically active radiation (PAR), derived from actual sunshine hours, and the assimilation-light response curve, to be 128 t CH2O ha−1year−1. A for non-closed canopies was calculated by correcting for the degree of light transmission, which in turn was estimated from recorded leaf area index values (L), i.e. the total leaf area per unit ground area.Forty-eight percent of gross assimilation was used for DM production, about half of this being lost in growth respiration. The remaining 52% was lost in maintenance respiration. These losses appeared to level off before crown expansion was completed, and since trunk biomass continued to increase, maintenance respiration per unit biomass (R) decreased with age.An increase in planting density reduced the assimilates available for bunch DM, had little effect on those for vegetative growth, but strongly reduced maintenance respiration and, since biomass was little affected, reduced R. Assimilates for bunch DM ha−1reached a maximum at L = 5.6.The observed trends in R as a function of palm age and planting density merit further study.

The Medical Expert Aid Committee

Potted Shiraz grapevines, in a glasshouse, were exposed to two different soil temperatures (13°C and 23°C) to evaluate the effects on vegetative growth and floral development from dormancy to anthesis. Soil temperature had no effect on the time of budbreak, anthesis, or the number of flowers per inflorescence. At anthesis total biomass was similar for both treatments, whereas shoot biomass was greater in the warm soil. From dormancy to anthesis, both root and trunk biomass decreased in the cool soil and only root biomass decreased in the warmer soil, but by twice as much as that in the cool soil. During dormancy to anthesis decreases in total nonstructural carbohydrate accounted for most of the decrease in root biomass. At budbreak, 14 cytokinins representing four recognized classes were present in bleeding sap, with <i>trans</i>-zeatin riboside and isopentenyl adenosine as the dominant forms. Total and active free base cytokinin concentrations were similar for both treatments, while sap from vines in the warm soil had significantly lower concentrations of nucleotide cytokinins. However, delivery of cytokinins was significantly greater in the warm soil treatment. By anthesis, cytokinin concentrations were similar for both treatments, but total cytokinin concentrations in xylem sap had decreased by almost 90% from budbreak. Root-generated cytokinins appear to be associated with the mobilization of the carbohydrate reserves at the end of dormancy and the ensuing shoot growth. Comparison of results with those of previous studies reveals that, because of apical dominance and correlative inhibition, the response to soil temperature in terms of number of buds to break and time of budbreak is conditioned by the number of nodes per cane.