Aboveground Biomass Increment Research Articles

Net primary production and nutrient cycling in replicated stands of Eucalyptus saligna and Albizia facaltaria

Production and nutrient cycling budgets were estimated at three locations within 1 km on the island of Hawaii, for replicated plantations of Eucalyptus saligna Sm. and nitrogen-fixing Albizia facaltaria (L.) Fosberg (= Paraserianthes facaltaria (L.) Nielson)). At the age of 16 years, the aboveground biomass of Eucalyptus averaged 323 Mg/ha, about 50% more than the 216 Mg/ha of Albizia biomass. Net primary production (NPP) was about 40 Mg ha −1 year −1 for both species. Eucalyptus allocated 45% of NPP to stem production, compared with 34% of Albizia ( p=0.02). Conversely, Eucalyptus allocated less production belowground (29% of NPP) than did Albizia (41% of NPP, p<0.01). Litterfall mass did not differ between species, but differences in litterfall nutrient concentrations led to greater litterfall cycling of N and P for Albizia than for Eucalyptus (141 vs. 105 kg N ha −1; 6.2 vs. 4.8 kg P ha −1 year −1). The rate of N cycling in the aboveground-increment plus litterfall did not differ significantly between species. Lower soil P supply under Albizia may be partially responsible for the high ratio of belowground:aboveground production for Albizia. The mean annual increment (MAI) of aboveground biomass of Eucalyptus for 16 years was 20.2 Mg ha −1 year −1, which is not different from the annual increment of 19.3 Mg ha −1 year −1 between the age of 14 and 16 years. The MAI for Albizia (13.5 Mg ha −1 year −1) also matched the annual increment (13.9 Mg ha −1 year −1) from ages 14–16. The sustained high productivity of these stands may warrant longer rotation periods than currently recommended, especially on fertile soils or in silvicultural systems with high rates of fertilization.

The biological sustainability of biomass harvesting

This study was conducted to compare the effects of different harvesting patterns on grasslands and shrublands in order to suggest sustainable patterns for biomass fuel harvesters. Half-yearly harvest reduced the percentage cover of the vegetation from 96% to 83% over 2 yr. Yearly and half-yearly harvest eliminated four and five species, respectively. More species were observed on the uncut than on often-cut hills. Shoot densities under harvest increased over 2 yr. The aboveground biomass (AB) under yearly and half-yearly harvest declined significantly from 610.2 and 610.1 g m −2 in August 1989 to 261.8 and 143.9 g m −2 in August 1991, respectively. AB was higher in August than in February under half-yearly harvest and on the uncut than on often-cut hills. Moderate harvest increased aboveground biomass increment (ABI) with the largest 2-yr-long ABI (28 g m −2 month −1) for yearly harvest. ABI was larger from mid-February to mid-August than from mid-August to mid-February. Under half-yearly harvest from mid-August 1989 to mid-August 1991, aboveground nutrient storage decreased significantly from 3691 (N), 323 (P) and 4996 mg m −2 (K) to 1081 (N), 108 (P) and 932 mg m −2 (K). It was higher in August than in February. Yearly harvest had the highest 2-yr-long photosynthetically active radiation (PAR) conversion efficiency (0.26%) and 2-yr-long aboveground N, P and K increment (195, 18 and 207 mg m −2 month −1, respectively). PAR conversion efficiency and aboveground nutrient increment were higher from mid-February to mid-August than from mid-August to mid-February. Biyearly to yearly harvests from August onwards are sustainable patterns.

Allocation of carbon in a mature eucalypt forest and some effects of soil phosphorus availability

Pools and annual fluxes of carbon (C) were estimated for a mature Eucalyptus pauciflora (snowgum) forest with and without phosphorus (P) fertilizer addition to determine the effect of soil P availability on allocation of C in the stand. Aboveground biomass was estimated from allometric equations relating stem and branch diameters of individual trees to their biomass. Biomass production was calculated from annual increments in tree diameters and measurements of litterfall. Maintenance and construction respiration were calculated for each component using equations given by Ryan (1991a). Total belowground C flux was estimated from measurements of annual soil CO2 efflux less the C content of annual litterfall (assuming forest floor and soil C were at approximate steady state for the year that soil CO2 efflux was measured). The total C content of the standing biomass of the unfertilized stand was 138 t ha-1, with approximately 80% aboveground and 20% belowground. Forest floor C was 8.5 t ha-1. Soil C content (0–1 m) was 369 t ha-1 representing 70% of the total C pool in the ecosystem. Total gross annual C flux aboveground (biomass increment plus litterfall plus respiration) was 11.9 t ha-1 and gross flux belowground (coarse root increment plus fine root production plus root respiration) was 5.1 t ha-1. Total annual soil efflux was 7.1 t ha-1, of which 2.5 t ha-1 (35%) was contributed by litter decomposition.

Evaluating a simple radiation/dry matter conversion model using data from Eucalyptus globulus plantations in Western Australia.

A simple model that describes growth in terms of physical and physiological processes is needed to predict growth rates and hence the productivity of trees at particular sites. The linear relationship expected between absorbed photosynthetically active radiation (phi(pa), MJ m(-2)) and dry mass production (G(t)); i.e., G(t) = epsilonphi(pa), where epsilon is the radiation utilization coefficient, was fitted to three years' data from five Western Australian Eucalyptus globulus Labill. plantations for which monthly growth measurements, leaf area indices, weather data and soil water measurements were available. Reductions in growth efficiency relative to absorbed photosynthetically active radiation were associated with high vapor pressure deficits (D, kPa) so the relationship between monthly aboveground biomass increments and D was used to calculate utilizable phi(pa). Plotting cumulative aboveground growth against utilizable phi(pa) gave strong linear relationships with slope epsilon. Values of epsilon ranged from 0.93 to 2.23 g dry mass MJ(-1) phi(pa). The variation could not be explained either in terms of soil water content in the root zones, because all plantations appeared to have access to groundwater, or in terms of soil chemistry. A value of epsilon approximately 2.2 is considered near the maximum likely to be applicable to Eucalyptus plantations. An interesting peripheral finding was a strong relationship between allometric ratios and soil phosphorus; this, if confirmed elsewhere, will be of considerable value in converting biomass increments to wood production. There was also a strong negative relationship between the average ratio of leaf/total aboveground biomass and soil nitrogen content.

Cycle de la matière organique et gestion des bioéléments dans un peuplement de hêtre (Fagus sylvatica L.) de l’Etna

A beech (Fagus sylvatica L.) forest stand, with 2125 stems per hectare, from the highest part of the Etna volcano (Sicily) was estimated, from representative samples of whole trees, as having an above-ground biomass of 132 Mg ha-1 (128 Mg ha-1 woody material ; 4 Mg ha-1 leaves). Corresponding root biomass has been estimated at 25 Mg ha-1, according to the observations of other authors. Above-ground biomass included 327 kg ha-1 of calcium, 141 of potassium, 94 of nitrogen and 35, 27, 8 and 2 kg ha-1 of magnesium, phosphorus, iron and manganese respectively. Yearly increment of above-ground perennial biomass amounted to 7.9 Mg ha-1, immobilizing 20 kg ha-1 year-1 of Ca, 7 of K, 4 of N and respectively 2, 1, 0.5 and 0.2 kg ha-1 year-1 for the other 4 nutrients studied. Litter-fail amounted to 3.9 Mg ha-1 year-1, with 3.5 Mg ha-1 being leaf-litter. Contained within litter-fall, 33 kg ha-1 year-1 of Ca, 20 and 19 of N and K, 5, 4, 1 and 0.1 kg ha-1 year-1 of Mg, P, Fe and Mn are returned to the soil each year. Above-ground litter layer amounted to 13 Mg ha-1, including 20, 7, 4, 2, 1, 0.5 and 1 kg ha-1 of Ca, K, N, Mg, P, Fe and Mn respectively. If the amounts of the various compartments, and the fluxes of organic matter and nutrients are very close to those determined for other even-aged Fagus sylvatica L. stands elsewhere in Europe, nitrogen contents are comparatively very low. This probably results from the low nitrogen availability in the soils of the Etna volcano.

Assessment of carbon allocation and biomass production in a natural stand of the salt marsh plant Spartina anglica using 13C

The proportional allocation of photosynthetically fixed carbon to the root and shoot system of salt marsh plants is an important element in the carbon cycle of tidal salt marshes. The commonly applied field methods giving insight on this point are based on successive harvesting of biomass. These methods, however, lack accuracy and do not yield reliable data over short time intervals. In the present study, the stable carbon isotope C-13 was used as a tracer of carbon flow in Spartina anglica. Shoot clusters of this halophyte were incubated with (CO2)-C-13 (ca 1 h) in a salt marsh in the SW Netherlands. Four days after the incubations, shoots and roots/rhizomes were sampled to determine enrichment with the heavy isotope. Although S. anglica is a clonal plant, only a minor part of the excess C-13 incorporated in plant tissues due to the incubation procedure was found outside the incubation plots. The data revealed the dynamic nature of carbon allocation in S. anglica, leading to seasonal changes in the ratio of carbon allocated to above-ground versus below-ground tissues. The ratio was highest in August (6.19) and lowest in September (1.60), but more carbon was always invested in above-ground plant parts than in below-ground plant parts. These findings strongly suggest that, on an annual basis, above-ground biomass production outweighs below-ground biomass production in this S. anglica population. Root/rhizome production over short-term periods (10 to 12 d) was calculated by combining the data on the ratios of C-13 allocation with measurements of above-ground biomass increments over these periods. On an annual basis, above-ground and below- ground biomass production was estimated to be 1130 and 556 g dry wt m(-2), respectively. A survey of the Literature shows that the ratio of shoot to root/rhizome production of Spartina spp. vegetation is highly variable, ranging from a clear dominance of shoot production (as is suggested by our data) to the completely opposite situation with root/rhizome production amply exceeding shoot production. This may imply considerable differences in the functioning of Spartina-dominated marsh systems, e.g. with respect to the dominance of aerobic or anaerobic mineralization processes and to mineralization-linked cycling of sulphur and nitrogen. [KEYWORDS: spartina anglica; salt marshes; carbon allocation; production; stable carbon isotopes Belowground biomass; alterniflora loisel; sulfate reduction;dynamics; georgia; roots; isotope; decomposition; netherlands;patterns]

Maintenance and growth respiration of the aboveground parts of young field-grown hinoki cypress (Chamaecyparis obtusa).

Aboveground respiration of five 8-year-old trees of field-grown hinoki cypress (Chamaecyparis obtusa (Sieb. et Zucc.) Endl.) was nondestructively measured at monthly intervals over 1 year with an enclosed standing tree method. The relationship between monthly specific respiration rate and monthly mean relative growth rate at the individual tree level was described by a linear equation. During the dormant season, respiration was used mainly for maintenance purposes, whereas during the growing season, more than 40% of the respiration was used for growth purposes, i.e., 60 to 70% in May. We conclude that annual maintenance and growth respiration of a tree are directly proportional to the aboveground phytomass and its annual increment, respectively. The maintenance coefficient was estimated to be 0.504 +/- 0.039 (SE) kg kg(-1) year(-1), indicating that the amount respired for maintaining already existing phytomass was equivalent to about half of the existing phytomass. The growth coefficient was estimated to be 0.772 +/- 0.043 (SE) kg kg(-1), indicating that the amount respired for constructing new phytomass was equivalent to about three-fourths of the annual phytomass increment. The annual stand maintenance and growth respiration were, respectively, 8.8 Mg ha(-1) year(-1) for an aboveground biomass of 17.4 Mg ha(-1) and 5.0 Mg ha(-1) year(-1) for an annual stand aboveground biomass increment of 6.5 Mg ha(-1) year(-1). About two-thirds of the total respiration was used to maintain already existing biomass, and about one-third was used to construct new biomass.

Forest growth along a rainfall gradient in Hawaii: Acacia koa stand structure, productivity, foliar nutrients, and water- and nutrient-use efficiencies.

We tested whether variation in growth of native koa (Acacia koa) forest along a rainfall gradient was attributable to differences in leaf area index (LAI) or to differences in physiological performance per unit of leaf area. Koa stands were studied on western Kauai prior to Hurricane Iniki, and ranged from 500 to 1130 m elevation and from 850 to 1800 mm annual precipitation. Koa stands along the gradient had basal area ranging from 8 to 42 m2/ha, LAI ranging from 1.4 to 5.4, and wood increment ranging from 0.7 to 7.1 tonnes/ha/year. N, P, and K contents by weight of sun leaves (phyllodes) were negatively correlated with specific leaf mass (SLM, g m-2) across sites; on a leaf area basis, N increased whereas P and K decreased with SLM. LAI, aboveground woody biomass increment, and production per unit leaf area (E) increased as phyllode δ13C became more negative. The δ13C data suggested that intrinsic water-use efficiency (ratio of assimilation to conductance) increased as water availability decreased. In five of the six sites, phyllode P contents increased as LAI increased, but biomass increment and E were not correlated with phyllode nutrient contents, suggesting that productivity was limited more by water than by nutrient availability. Because vapor pressure deficits increased with decreasing elevation, actual water-use efficiency (ratio of assimilation to transpiration) was lower at drier, low-elevation sites. There was a trade-off between intrinsic water-use efficiency and production per unit of canopy N or P across the gradient. In summary, koa responds to water limitation both by reducing stand LAI and by adjusting gas exchange, which results in increased intrinsic water-use efficiency but decreased E.

Productivity of needles and allocation of growth in young Scots pine trees of different competitive status

It has been suggested that the allocation of carbon to stem wood growth has low priority, and that productivity of needles (above-ground tree biomass increment per unit leaf weight) decreases as competition between trees increases. To test this, carbon allocation to different growth components and productivity of needles were compared between trees of different tree classes (dominant, codominant, intermediate and suppressed). The study was carried out in two 16-year-old Scots pine ( Pinus sylvestris L.) stands, planted at different initial densities: 40 000 and 10 000 seedlings ha −1. It was found that the allocation of carbon to stem wood production, and probably also fine root production, has high priority for trees under hich competitive stress. It was also found that production per unit weight of needles increases with competition; at least for as long as the trees are experiencing approximately the same light regime.

Response of aboveground biomass increment, growth efficiency, and foliar nutrients to thinning, fertilization, and pruning in young Douglas-fir plantations in the central Oregon Cascades

The effect of thinning and cultural practices (multinutrient fertilization, pruning) on total aboveground biomass increment and growth efficiency was studied over three consecutive 2-year periods (1981–1987) in young Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) plantations. Net aboveground biomass increment over the 6-year period averaged 14.5, 7.8, and 5.5 Mg•ha−1•year−1 for the high-, medium-, and low-density plots, respectively. Growth efficiency, after dropping sharply between leaf area indexes of 1 and 6 m2/m2, remained relatively constant up to a leaf area index of 17, the highest measured. Consequently, aboveground biomass increment continued to increase at leaf area indexes well above that at which the Beer–Lambert law predicts maximum light should be absorbed. Foliage analyses indicate that thinning improved nitrogen, potassium, and magnesium nutrition and increased the translocation of potassium from 1-year-old foliage to support new growth. However, fertilization increased foliar nitrogen and phosphorus contents only when coupled with pruning, suggesting that trees favor total leaf area over individual needle nutrition. Indications of potassium and magnesium limitations in this study are supported by other recent studies in Douglas-fir. Further work on the role of multinutrient deficiencies in this species is warranted.

Is primary production in holm oak forests nutrient limited?

Correlations between primary production and patterns of nutrient use and nutrient availability were investigated in 18 plots in closed holm oak (Quercus ilex L.) stands in the Montseny mountains (NE Spain), searching for evidence of nutrient limitation on primary production. The plots spanned a range of altitudes and slope aspects within a catchment. Nutrients considered were nitrogen (N), phospho­ rus (P), potassium (K) and magnesium (Mg) in plant samples, and the above plus calcium (Ca) and sodium (Na) in the soil. Primary production was found by summing the annual aboveground biomass increment to the annuallitterfall. Across plots, primary production was correlated with the annual re­ turn of nutrients in litterfall, but this relationship probably arose from the common effects of the amount of litterfall on both primary production and nutrient return, and not from any nutrient limitation. Pri­ mary production was not significantly correlated with nutrient concentrations in mature leaves nor leaf litterfall, nor with absolute or relative foliar retranslocation of nutrients before leaf abscission, nor with the concentration and content (kg/ha) of total N, extractable P, and exchangeable K, Mg, Ca and Na in the upper mineral soil. We conclude that there is no correlational evidence that primary production is nutrient limited in this holm oak forest.

Dynamics of Canopy Structure and Light Interception in Pinus Elliottii Stands, North Florida

In order to develop a model of the carbon cycle for mature slash pine (Pinus elliottii) stands in north Florida, we studied seasonal variation in leaf area index (LAI, allsided), aboveground biomass increment and litterfall, and light penetration through the forest canopy, over a 3—yr period. The primary approach to establishing monthly LAI included annual destructive analyses and monthly measurements of needle fall and elongation. Imagery from the Landsat Thematic Mapper (TM) and pattern of light penetration were also used in attempts to derive less ardouous estimates; the TM imagery was most promising. LAIs ranged from 3.0 to 6.5 on control plots over the 3 yr, with repeated fertilization increasing maximum LAI by &gt;40%. Seasonal variation was high (40%), as was variation from year to year. An average of 31% of the incident photosynthetically active radiation (PAR) penetrated the canopies annually, ranging from 18 to 42% seasonally. Seasonal light penetration could not be described using a simple application of the Beer—Lambert law, perhaps due to the highly aggregated nature of the canopies. Models incorporating more information on canopy structure are necessary to predict light penetration through slash pine stands accurately. A model of needle litterfall was derived that could account for much of the seasonal and annual variation using stand basal area and climate conditions from the spring of the previous year; this model may be useful for developing climate—driven predictions of LAI. Efficiencies of use of incoming and intercepted PAR were low compared to other forest types. Low light interception and high nutrient—use efficiencies (demonstrated in earlier studies) are important adaptive characteristics of slash pine stands to these relatively warm and nutrient—poor sites.

Biomass Production of Short RotationEucalyptus camaldulensisDehn. Stands Growing on Peat Soil under a High Water Table in Israel

SYNOPSIS The growth and production of Eucalyptus camaldulensis Dehn. was studied under a four-year rotation on neutral and acid peat soils in the Hula Valley, Israel. The water table at the site was 1 m to 2 m for most of the year and the trees were planted at stocking densities of 1100, 1670 and 3300 trees per hectare. The local combination of fertile soil, high water table and high temperature created excellent growing conditions and produced remarkably high biomass tonnages and energy production values. Biomass production was not affected by either the type of peat or stocking per ha above 1670 stems. The mean annual increment of above-ground biomass and mean annual energy production were 51 t (o.d.) per hectare per year and 1008 MJ/ha per year for stocking densities of 1670 stems/ha.

The relationship of above-ground dry matter accumulation by Pinus radiata to intercepted solar radiation and soil water status

A simple empirical model is described in which monthly above-ground biomass increments are related to estimates of the amount of short-wave energy absorbed by the canopy. The efficiency with which photosynthetic energy is used is a function of soil water status. Energy absorption and water use are functions of current above-ground biomass. The model is tested against three above-ground Pinus radiata D.Don biomass data sequences from climatologically different sites. The sensitivity of the model to changes in its constituent relationships is explored as an indication of areas to which future studies should be directed.

A comparison of vegetative cover and tree community structure in three forested Adirondack watersheds

The Integrated Lake–Watershed Acidification Study (ILWAS) was conducted using three forested watersheds (Panther, Sagamore, and Woods) in the central Adirondack Park of New York State. By comparing the biogeochemical behavior of these watersheds, the ILWAS investigators hoped to elucidate the major ecosystem parameters controlling the fate of strong acids introduced from the atmosphere to lake–watershed systems. The ILWAS vegetation research program was designed to compare the quantitative patterns of forest structure in these midelevation watersheds. Results showed that the ILWAS catchments contain closely related variants of the northern hardwood – spruce – fir complex of the Adirondack region. The dominant tree species in these watersheds are beech (Fagusgrandifolia Ehrh.), red spruce (Picearubens Sarg.), sugar maple (Acersaccharum Marsh.), red maple (Acerrubrum L.), and yellow birch (Betulaalleghaniensis Britt.). On an areal basis, the watersheds contain 57–88% hardwood cover type and 5–29% spruce–fir cover type. Mean live basal area values range from 22 to 30 m2 ha−1 between catchments, while standing dead basal area values range from 4 to 8 m2 ha−1. Mean live stem densities range from 1400 to 1700 stems ha−1. Mean aboveground biomass projections for the tree stratum in the three watersheds range from 143 to 199 Mt ha−1, while estimated aboveground annual biomass increments range from 4.1 to 5.3% of standing biomass.

Biomass and elemental uptake in fertilized and unfertilizedBetula papyrifera Marsh. andPopulus grandidentata Michx.

Estimates were made of the above-ground biomass and contents of N, P, K, Ca, Mg, Mn, Na, Fe, Zn, Al, and Cu in fertilized (N 448 kg/ha, P 112 kg/ha, lime 4480 kg/ha) and unfertilized white birch (Betula papyrifera Marsh.) and bigtooth aspen (Populus grandidentata Michx.). For individuals of both species, fertilization increased the average above-ground biomass increment and the N and P content increment by 150 per cent and 300 per cent, respectively, but decreased uptake of Mn and Zn. The allocation of biomass and elements differs not only between species, but within species under untreated and fertilized conditions.

Old‐Growth Pseudotsuga menziesii Communities of a Western Oregon Watershed: Biomass Distribution and Production Budgets

Living biomass, organic matter distribution, and organic matter production budgets were determined for plant communities of a small watershed dominated by 450—yr—old Pseudotsuga menziesii (Mirb.) Franco forests. Dominant trees in the communities were large, up to 175 cm diam and 80 m tall. Aboveground tree biomass of the various communities ranged from 491.8—975.8 tonnes/hectare, total aboveground living biomass ranged from 500.4—982.5 t/ha, total leaf biomass ranged from 10.4—16.3 t/ha and total organic matter accumulations ranged from 1,008.3—1,513.7 t/ha. Total tree biomass in the various communities was more related to past mortality than habitat differences. Biomass of standing dead trees and fallen logs was generally inversely related to aboveground tree biomass. Amounts of woody detritus were large, ranging from 59.0—650.6 t/ha or 4.3%—43.0% of total community organic accumulation. Aboveground tree biomass increment was negative in all communities, ranging from —2.9 to —6.2 t/ha. Positive increment by shrubs and trees &lt;15 cm dbh, produced overall aboveground biomass increment —2.5 to —5.0 t/ha. Mortality averaged 1% of standing biomass. Aboveground net primary production in the various communities ranged from 6.3 to 10.1 t°ha—1°—1 and was roughly proportional to standing biomass. Net primary production consisted entirely of detritus. Total community autotrophic respiration ranged from 102.9—203.7 t°ha—1°yr—1 of which °70% was by foliage. Gross primary production ranged from 111.2—216.8 t°ha—1°yr—1 of which only 6.0%—7.9% was net primary production. Net ecosystem production ranged from 0.12—5.6 t°ha—1°yr—1, entirely as an accumulation of woody detritus on the soil surface. Available evidence indicates larger peak biomass in seral P. menziesii than in climax Tsuga heterophylla forests. These communities may be in the process of declining from seral peak to steady—state climax biomass.