Aboveground biomass and litterfall ofPinus pumila scrubs growing on the Kiso mountain range in central Japan

Aboveground biomass and litterfall ofPinus pumila scrubs, growing on the Kiso mountain range in central Japan, were investigated from 1984 to 1985. The biomass of two research plots (P1 and P2) with different scrub heights was estimated by two methods, the stratified clip technique and the allometric method. Aboveground total biomass estimated by the latter method reached 181 ton d.w. ha⁻¹ in P1 and 132 ton d.w. ha⁻¹ in P2. Creeping stems contributed to about half of the total biomass. Although estimates of woody organs differed between the two plots, leaf biomass estimates were almost the same at 15.5 ton d.w. ha⁻¹. The canopies of the twoP. pumila scrubs were characterized by a large mean leaf area density of 5.0 m² m⁻³. Despite this large area density, relatively moderate attenuation of light intensity was observed. Specific leaf area generally increased with reduced leaf height. Annual total litterfall was estimated to be 3.60 ton d.w. ha⁻¹ yr⁻¹ in P1 and 2.39 ton d.w. ha⁻¹ yr⁻¹ in P2. Annual leaf fall in both plots was approximately 2.0 ton d.w. ha⁻¹ yr⁻¹. Leaves fell mainly in early autumn. Annual loss rates of branches, estimated as the sum of annual branch litterfall and the amount of newly formed attached dead branches, were 0.29 ton d.w. ha⁻¹ yr⁻¹ in P1 and 0.37 ton d.w. ha⁻¹ yr⁻¹ in P2.     

Biomass and aboveground net primary production in a subtropical mangrove stand of Kandelia obovata (S., L.) Yong at Manko Wetland, Okinawa, Japan

Biomass and aboveground net primary production (ANPP) in a monospecific pioneer stand of a mangrove Kandelia obovata (S., L.) Yong were quantified. The estimated biomasses in leaves, branches, stems, roots, aboveground and total were 5.61 (3.68%), 28.8 (18.9%), 46.1 (30.2%), 71.8 (47.2%), 80.5 (52.8%) and 152 Mg ha⁻¹ (100%), respectively. Stem phytomass increment per tree was estimated using allometric relationships and stem analysis. Stem volume without bark of harvested trees showed a strong allometric relationship with D _0.1² H (D _0.1, diameter at a height of one-tenth of tree height H) (R ² = 0.924). Annual stem volume increment per tree showed a strong allometric relationship with D _0.1² H (R ² = 0.860). Litterfall rate ranges from 3.87 to 56.1 kg ha⁻¹ day⁻¹ for leaves and 0.177 to 46.2 kg ha⁻¹ day⁻¹ for branches. Seasonal changes of litterfall rate were observed, which showed a peak during wet season (August–September). Total annual litterfall was estimated as 10.6 Mg ha⁻¹ year⁻¹, in which 68.2% was contributed by the leaves. The ANPP in the K. obovata stand was 29.9–32.1 Mg ha⁻¹ year⁻¹, which is ca. 2.8–3.0 times of annual litterfall. The growth efficiency (aboveground biomass increment/LAI) was 5.35–5.98 Mg ha⁻¹ year⁻¹. The low leaf longevity (9.3 months) and high growth efficiency of K. obovata makes it a highly productive mangrove species.     

Diurnal and seasonal changes in the intensity of photosynthesis in stems of lilac (Syringa vulgaris L.)

It has been demonstrated that during the whole year the stems are photosyntheticaly active and capable of assimilating atmospheric CO₂. The intensity of photosynthesis varies. During the vegetation period the registered net photosynthesis lasted up to 13 hours per day, and in the leafless period for 2–3 hours a day. Photosynthesis was registered also at temperatures below zero (−3 °C) as a reduced CO₂ evolution in light in comparison with darkness. The maximal net photosynthesis values during the vegetation period amounted to 6 up 8 μmol (CO₂)·m⁻²·s⁻¹, and in the leafless period 0.5 – 1 μmol (CO₂)·m⁻²·s⁻¹, and they were close to being up to twice as big as the values obtained of darkness respiration. An increase of the photosynthetic activity of stems preceded the spring development of the leaves.     

Nitrate and ammonium accumulation in bermudagrass in relation to nitrogen fertilization and season

Seasonal changes in nitrate and ammonium concentrations were studied inCynodon dactylon (L.) Pers. plants grown for one year in the field in a Mediterranean area. Plants cultivated in a sandy loam soil were fertilized with nitrate-N or ammonium-N at two application rates (250 and 1000 kg N ha⁻¹ year⁻¹) and compared to controls with no added N. Plots were harvested every three weeks from May to November. Shoots were separated into leaves and stems and analyses carried out in both fractions. Nitrogen applications generally led to elevated nitrate concentrations both in leaves and stems at all sampling dates but had little influence on the ammonium concentrations of the tissues. Higher nitrate and ammonium concentrations were found in stems than in leaves, although no levels higher than 0.22% NO ₃ ⁻ −N and 0.10% NH ₄ ⁺ −N were detected in either fraction. Nitrate tended to accumulate mostly in autumn and spring whereas low accumulations were found in summer. Ammonium showed both in leaves and stems a progressive but limited accumulation throughout the period with a peak in October, followed by a strong decrease in November.     

Size-dependent variability of leaf and shoot hydraulic conductance in silver birch

Variation in leaf and shoot hydraulic conductance was examined on detached shoots of silver birch (Betula pendula Roth), cut from the lower third (shade leaves) and upper third of the crown (sun leaves) of large trees growing in a natural temperate forest stand. Hydraulic conductances of whole shoots (K _S), leaf blades (K _lb), petioles (K _P) and branches (i.e. leafless stem; K _B) were determined by water perfusion using a high-pressure flow meter in quasi-steady state mode. The shoots were exposed to irradiance of photosynthetic photon flux density of 200–250 μmol m⁻² s⁻¹, using different light sources. K _lb depended significantly (P < 0.001) on light quality, canopy position and leaf blade area (A _L). K _lb increased from crown base to tree top, in parallel with vertical patterns of A _L. However, the analysis of data on shade and sun leaves separately revealed an opposite trend: the bigger the A _L the higher K _lb. Leaf anatomical study of birch saplings revealed that this trend is attributable to enhanced vascular development with increasing leaf area. Hydraulic traits (K _S, K _B, K _lb) of sun shoots were well co-ordinated and more strongly correlated with characteristics of shoot size than those of shade shoots, reflecting their greater evaporative load and need for stricter adjustment of hydraulic capacity with shoot size. K _S increased with increasing xylem cross-sectional area to leaf area ratio (Huber value; P < 0.01), suggesting a preferential investment in water-conducting tissue (sapwood) relative to transpiring tissue (leaves), and most likely contributing to the functional stability of the hydraulic system, essential for fast-growing pioneer species.     

Biomass and net production in a bambooPhyllostachys bambusoides stand

Biomass and net production were measured in aPhyllostachys bambusoides stand in Kyoto Prefecture, central Japan, which had carried out gregarious flowering in 1969 and has been recovering vegetatively. The culm density fluctuated around an average value of 12 040 ha⁻¹ during the research period (1985–91). Annual recruirment and mortality rates of culms were 1340 and 1133 ha⁻¹, respectively. The mean diameter at breast height increased from 7.28 cm in 1985 to 8.68 cm in 1991, and the biomass of culms increased from 71.3 to 111.6t ha⁻¹ over the same time period. Branch and leaf biomasses were almost constant, 10.0 and 9.4t ha⁻¹ on average, respectively. The leaf area index of the stand was 11.6 ha ha⁻¹, which is one of the largest values found in Japanese forests. The belowground biomass of 32.6t ha⁻¹ for rhizomes and 14.8t ha⁻¹ for fine roots resulted in the smaller ratio of aboveground parts to the root system (2.38) than those determined for forest stands. The amount of litterfall, excluding culms and large branches, was large (9.13t ha⁻¹ year⁻¹), corresponding to those measured in equatorial stands. The aboveground net production was 24.6t ha⁻¹ year⁻¹, larger than the average value reported for forest stands under similar weather conditions.     

Development of ground vegetation biomass and nutrient pools in a clear-cut disc-plowed boreal forest

Nutrient leaching from forest substrate after clear-cutting and subsequent soil preparation is strongly influenced by the capacity of ground vegetation to sequester the released nutrients. We studied the rates and patterns of biomass and nutrient accumulation in ground vegetation growing on ridges, in furrows and on undisturbed surfaces for 2–5 years after disc-plowing in eastern Finland. The biomass of mosses on ridges remained significantly lower than that in furrows and on undisturbed surfaces. Field layer biomass on ridges and in furrows was significantly lower than on undisturbed surfaces throughout the study period. Field layer biomass increased more on ridges than in furrows. Root biomass on ridges and undisturbed surfaces was considerably higher than in furrows. Five years after disc-plowing, total biomass and nutrient pools for ridges (biomass 4,975 kg ha⁻¹, N 40 kg ha⁻¹, P 5 kg ha⁻¹, K 20 kg ha⁻¹ and Ca 18 kg ha⁻¹) and undisturbed surfaces (biomass 5,613 kg ha⁻¹, N 43 kg ha⁻¹, P 5 kg ha⁻¹, K 22 kg ha⁻¹ and Ca 18 kg ha⁻¹) were similar, but considerably lower for furrows (biomass 1,807 kg ha⁻¹, N 16 kg ha⁻¹, P 2 kg ha⁻¹, K 10 kg ha⁻¹ and Ca 6 kg ha⁻¹). Ridges covered 25% of the area, furrows 30 and 45% was undisturbed surfaces. Taking into account the proportion of each type of surface, values for the whole prepared clear-cut area were 4,312, 34, 4, 18 and 14 kg ha⁻¹ for biomass, N, P, K and Ca, respectively. Biomass and nutrient pools had not returned to uncut forest levels at the end of the 5-year study period. The results indicate that mosses and field layer vegetation respond differently to soil preparation, that the development of biomass on ridges, in furrows and on undisturbed surfaces proceeds at different rates, and that the biomass and nutrient uptake of ground vegetation remains below pre-site preparation levels for several years. However, ridges, which are known to be the most susceptible to leaching, revegetate rapidly. Responsible Editor: Tibor Kalapos.     

Productivity and mineral cycling in an oak coppice forest 2. Annual net production of the forest

Annual net production was estimated in the secondary coppice forest near Tokyo, which was dominated by a deciduous oak,Quercus serrata Thunb. Lateral growth of stems and old branches was directly estimated by examining the annual rings for 35 shoots in a clear-cut quadrat of 10m×10m. Phytomasses of current organs were also weighed in the quadrat. Preharvest losses of current organs were determined by twelve 0.5 m² litter traps for fine litter and twelve 6 m² quadrats for woody litter. Branch production was also assessed indirectly by use of the stem-branch allometry and death of branches. The results of the indirect method were in sufficient agreement with the result of the direct one. Grazing loss of leaves from the canopy was estimated directly from the loss in leaf area and indirectly from the animal faeces caught by the litter traps. Net production of the canopy trees was 149 kg a⁻¹ year⁻¹, in which leaf production was 36.9 kg. Animals grazed about 14% of the leaf area by the end of the growing season. True consumption of leaves by animals was 7.6% of leaf production or 10% of leaf mass. Production of undergrowth, mainly a dwarf bamboo,Pleioblastus chino Makino, was 28 kg a⁻¹ year⁻¹, being 15% of the total stand production. Productivity of this forest was significantly higher than that of cool-temperate deciduous broadleaf forests.     

Tree species and wood ash affect soil in Michigan’s Upper Peninsula

Tree species and wood ash application in plantations of short-rotation woody crops (SRWC) may have important effects on the soil productive capacity through their influence on soil organic matter (SOM) and exchangeable cations. An experiment was conducted to assess changes in soil C and N contents and pH within the 0–50 cm depth, and exchangeable cation (Ca²⁺, Mg²⁺, K⁺, and Na⁺) and extractable acidity concentrations within the 0–10 cm depth. The effects of different species (European larch [Larix decidua P. Mill.], aspen [Populus tremula L. × Populus tremuloides Michx.], and four poplar [Populus spp.] clones) and wood ash applications (0, 9, and 18 Mg ha⁻¹) on soil properties were evaluated, using a common garden experiment (N = 70 stands) over 7 years of management in Michigan’s Upper Peninsula. Soils were of the Onaway series (fine-loamy, mixed, active, frigid Inceptic Hapludalfs). The NM-6 poplar clone had the greatest soil C and N contents in almost all ash treatment levels. Soil C contents were 7.5, 19.4, and 10.7 Mg C ha⁻¹ greater under the NM-6 poplar than under larch in the ash-free, medium-, and high-level plots, respectively. Within the surface layer, ash application increased soil C and N contents (P < 0.05) through the addition of about 0.7 Mg C ha⁻¹ and 3 kg N ha⁻¹ with the 9 Mg ha⁻¹ ash application (twofold greater C and N amounts were added with the 18 Mg ha⁻¹ application). During a decadal time scale, tree species had no effects—except for K⁺—on the concentrations of the exchangeable cations, pH, and extractable acidity. In contrast, ash application increased soil pH and the concentration of Ca²⁺ (P < 0.05), from 5.2 ± 0.4 cmol_c kg⁻¹ (ash-free plots) to 8.6 ± 0.4 cmol_c kg⁻¹ (high-level ash plots), and tended to increase the concentration of Mg²⁺ (P < 0.1), while extractable acidity was reduced (P < 0.05) from 5.6 ± 0.2 cmol_c kg⁻¹ (ash-free plots) to 3.7 ± 0.2 cmol_c kg⁻¹ (high-level plots). Wood ash application, within certain limits, not only had a beneficial effect on soil properties important to the long-term productivity of fast-growing plantations but also enhanced long-term soil C sequestration.     

Dinitrogen-fixation by three neotropical agroforestry tree species under semi-controlled field conditions

Cultivating dinitrogen-fixing legume trees with crops in agroforestry is a relatively common N management practice in the Neotropics. The objective of this study was to assess the N₂ fixation potential of three important Neotropical agroforestry tree species, Erythrina poeppigiana, Erythrina fusca, and Inga edulis, under semi-controlled field conditions. The study was conducted in the humid tropical climate of the Caribbean coastal plain of Costa Rica. In 2002, seedlings of I. edulis and Vochysia guatemalensis were planted in one-meter-deep open-ended plastic cylinders buried in soil within hedgerows of the same species. Overall tree spacing was 1 × 4 m to simulate a typical alley-cropping design. The ¹⁵N was applied as (NH₄)₂SO₄ at 10% ¹⁵N atom excess 15 days after planting at the rate of 20 kg [N] ha⁻¹. In 2003, seedlings of E. poeppigiana, E. fusca, and V. guatemalensis were planted in the same field using the existing cylinders. The ¹⁵N application was repeated at the rate of 20 kg [N] ha⁻¹ 15 days after planting and 10 kg [N] ha⁻¹ was added three months after planting. Trees were harvested 9 months after planting in both years. The ¹⁵N content of leaves, branches, stems, and roots was determined by mass spectrometry. The percentage of atmospheric N fixed out of total N (%N_f) was calculated based on ¹⁵N atom excess in leaves or total biomass. The difference between the two calculation methods was insignificant for all species. Sixty percent of I. edulis trees fixed N₂; %N_f was 57% for the N₂-fixing trees. Biomass production and N yield were similar in N₂-fixing and non-N₂-fixing I. edulis. No obvious cause was found for why not all I. edulis trees fixed N₂. All E. poeppigiana and E. fusca trees fixed N₂; %N_f was ca. 59% and 64%, respectively. These data were extrapolated to typical agroforestry systems using published data on N recycling by the studied species. Inga edulis may recycle ca. 100 kg ha⁻¹ a⁻¹ of N fixed from atmosphere to soil if only 60% of trees fix N₂, E. poeppigiana 60–160 kg ha⁻¹ a⁻¹, and E. fusca ca. 80 kg ha⁻¹ a⁻¹.     

Dynamics of aboveground big woody organs in a foothill dipterocarp forest,West Sumatra,Indonesia

The dynamics of aboveground big woody organs over 10 cm diameter was studied at a mature foothill dipterocarp forest in West Sumatra. The biomass of big woody organs was estimated to be 519 m³ ha⁻¹ or 408 metric ton ha⁻¹ by means of a pipe model theory. The diameter distribution showed a convex curve and the mode was found at a diameter of about 20 cm. The standing mass of big dead woody litter on the forest floor was 116 m³ ha⁻¹, which accounted for 22% by voume or 9.5% by weight of the biomass of living organs respectively. Thedbh observation with two 1-ha plots for 4 yr and 5 yr respectively revealed that the average net production rate was 9.5 ton ha⁻¹ yr⁻¹. The death rate (7.9 ton ha⁻¹ yr⁻¹) accounted for 83% of the net production rate and was nearly equivalent to the decay rate (7.5 ha⁻¹ yr⁻¹) of dead wood on the forest floor. The balance between the death and decay rates was confirmed for each diameter class. Average turnover periods for big woody organs and dead woody litter were estimated to be 43 and 8.1 yr, respectively. Standing masses of live anddead woody materials accumulated in the study forest were approximately equal to those obtained in a mature tropical lowland rainforest, whereas the flow rates were lower, being only 70% of the corresponding values.     

Estimates of biomass and primary productivity in a high-altitude maple forest of the west central Himalayas

The paper describes the biomass and productivity of maple (Acer cappadocicum) forest occurring at an altitude of 2,750 m in the west central Himalayas. Total vegetation biomass was 308.3 t ha⁻¹, of which the tree layer contributed the most, followed by herbs and shrubs. The seasonal forest-floor litter mass varied between 5.4 t ha⁻¹ (in rainy season) and 6.6 t ha⁻¹ (in winter season). The annual litter fall was 6.2 t ha⁻¹, of which leaf litter contributed the largest part (59% of the total litter fall). Net primary productivity of total vegetation was 19.5 t ha⁻¹ year⁻¹. The production efficiency of leaves (net primary productivity/leaf mass) was markedly higher (2.9 g g⁻¹ foliage mass year⁻¹) than those of the low-altitude forests of the region.     

Soil nutrients affect spatial patterns of aboveground biomass and emergent tree density in southwestern Borneo

Studies on the relationship between soil fertility and aboveground biomass in lowland tropical forests have yielded conflicting results, reporting positive, negative and no effect of soil nutrients on aboveground biomass. Here, we quantify the impact of soil variation on the stand structure of mature Bornean forest throughout a lowland watershed (8–196 m a.s.l.) with uniform climate and heterogeneous soils. Categorical and bivariate methods were used to quantify the effects of (1) parent material differing in nutrient content (alluvium > sedimentary > granite) and (2) 27 soil parameters on tree density, size distribution, basal area and aboveground biomass. Trees ≥10 cm (diameter at breast height, dbh) were enumerated in 30 (0.16 ha) plots (sample area = 4.8 ha). Six soil samples (0–20 cm) per plot were analyzed for physiochemical properties. Aboveground biomass was estimated using allometric equations. Across all plots, stem density averaged 521 ± 13 stems ha⁻¹, basal area 39.6 ± 1.4 m² ha⁻¹ and aboveground biomass 518 ± 28 Mg ha⁻¹ (mean ± SE). Adjusted forest-wide aboveground biomass to account for apparent overestimation of large tree density (based on 69 0.3-ha transects; sample area = 20.7 ha) was 430 ± 25 Mg ha⁻¹. Stand structure did not vary significantly among substrates, but it did show a clear trend toward larger stature on nutrient-rich alluvium, with a higher density and larger maximum size of emergent trees. Across all plots, surface soil phosphorus (P), potassium, magnesium and percentage sand content were significantly related to stem density and/or aboveground biomass (R _Pearson = 0.368–0.416). In multiple linear regression, extractable P and percentage sand combined explained 31% of the aboveground biomass variance. Regression analyses on size classes showed that the abundance of emergent trees >120 cm dbh was positively related to soil P and exchangeable bases, whereas trees 60–90 cm dbh were negatively related to these factors. Soil fertility thus had a significant effect on both total aboveground biomass and its distribution among size classes. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Effect of rhizobia and rock biofertilizers with <Emphasis Type="Italic">Acidithiobacillus</Emphasis> on cowpea nodulation and nutrients uptake in a tableland soil

Chemical fertilizers have been used in the cultivation of plants due to their high solubility and effect on crops yield. Biofertilizers with phosphate rock (PR) and potash rock (KR) plus sulfur inoculated with Acidithiobacillus may improve plant growth and contribute to addition of available P and K in soil. The effectiveness of biofertilizers from phosphate and potash rocks mixed with sulfur and Acidithiobacillus was studied in a Typic Fragiuldult soil of the Brazilian Northeast Tableland. Cowpea (cv. “IPA 206”) was grown with and without rhizobia inoculation. Treatments were: (a) phosphate rock (1000 kg ha⁻¹); (b) Biofertilizers-B_P (250 and 500 kg ha⁻¹); (c) triple superphosphate-TSP (250 kg ha⁻¹); (d) potash rock (1000 kg ha⁻¹); (e) biofertilizer-B_K (250; 500 and 750 kg ha⁻¹); (f) potassium chloride-KCl (250 kg K₂0 ha⁻¹); (g) control without P or K fertilization (P₀K₀). The soil was maintained under water submersion covered with black plastic (solarization process) for a period of 30 days. Biofertilizers (B_p and B_K) and soluble fertilizers increased plant growth and NPK uptake. Biofertilizers reduced soil pH, especially when applied in highest rates. Biofertilizers and TSP+KCl showed the best values of available P and K in soil. Rhizobial inoculation was effective on cowpea, but no nodules were formed by bacteria native from the soil, probably due to the effect of the solarization process. From obtained PK biofertilizers could be used as alternative for cowpea fertilization in Tableland soils.     

Productivity, CO2/O2 exchange and hydraulics in outdoor open high density microalgal (Chlorella sp.) photobioreactors operated in a Middle and Southern European climate

Two variants of open photobioreactors were operated at surface-to-volume ratios up to 170 m⁻¹. The mean values for July and September obtained for photobioreactor PB-1 of 224 m² culture area (length 28 m, inclination 1.7%, thickness of algal culture layer 6 mm), operated in Třeboň (49^∘N), Czech Republic, were: net areal productivity, P _net = 23.5 and 11.1 g dry weight (DW) m⁻² d⁻¹; net photosynthetic efficiency (based on PAR – Photosynthetic Active Radiation), η = 6.48 and 5.98%. For photobioreactor PB-2 of 100 m² culture area (length 100 m, inclination 1.6%, thickness of algal culture layer 8 mm) operated in Southern Greece (Kalamata, 37^∘N) the mean values for July and October were: P _net = 32.2 and 18.1 g DW m⁻² d⁻¹, η = 5.42 and 6.07%. The growth rate of the alga was practically linear during the fed-batch cultivation regime up to high biomass densities of about 40 g DW L⁻¹, corresponding to an areal density of 240 g DW m⁻² in PB-1 and 320 g DW m⁻² in PB-2. Night biomass loss (% of the daylight productivity, P _L) caused by respiration of algal cells were: 9–14% in PB-1; 6.6–10.8% in PB-2. About 70% of supplied CO₂ was utilized by the algae for photosynthesis. The concentration of dissolved oxygen (DO) increased from about 12 mg L⁻¹ at the beginning to about 35 mg L⁻¹ at the end of the 100 m long path of suspension flow in PB-2 at noon on clear summer days. Dissipation of hydraulic energy and some parameters of turbulence in algal suspension on culture area were estimated quantitatively.     

Allometry of aboveground biomasses in mangrove species in Itamaracá, Pernambuco, Brazil

Allometric equations to estimate aboveground biomass (AGB) and plant part biomasses (PPB) of three mangrove species, Rhizophora mangle, Avicennia schaueriana, and Laguncularia racemosa, were determined in Itamaracá, Pernambuco, Brazil (7°48′44″S and 34°49′39″W). Twenty-three to thirty-six trees of each species, ranging in height (H) from 1.6 to 11.8 m and in diameter, at breast height or above prop roots (D), from 2 to 21 cm, were measured, cut, and separated into stems, branches, leaves, and prop roots. Biomass proportions in each tree part were similar among species, excluding prop roots: stems 37–47%, branches 41–46%, and leaves 11–17%. Prop roots represented 37% of AGB in R. mangle. Tree size had a significant but not large influence on biomass distribution among plant parts: as stem diameters increased the proportions allocated to leaves decreased and those to stems and branches increased. AGB and PPB were significantly related to D and D² × H and the best fittings were obtained with power equations. A few equations from literature fitted the data reasonably well for AGB of one or two of the species but resulted in large errors for the others. Applying the equations to previous measurements of tree diameters in a sample area, AGB for the mangrove site was estimated at 105 Mg ha⁻¹, with 78, 19, and 3% corresponding to biomasses of R. mangle, L. racemosa, and A. schaeuriana trees, respectively.     

Methane Budget of a Black Forest Spruce Ecosystem Considering Soil Pattern

Study included seven soils, an adjacent spring and brook and was conducted to estimate CH₄ source and sink strengths of forest soils along a wetness gradient, i.e. their exchange with atmosphere (direct emission), and hydrosphere (indirect emission). Soils are represented by anaerobic Histosol, oxic Cambisols, Histosol with degraded peatlayers and Gleysols having intermediate redox state. They could be separated into three emission groups: CH₄ emitting (248–318 kg C ha⁻¹ a⁻¹), CH₄ uptake (−0.1 to −5 kg C ha⁻¹ a⁻¹), and soils on the edge of CH₄ uptake and release (−0.2–20 kg C ha⁻¹ a⁻¹). Although soils with CH₄ uptake were dominant (75%), the soil specific CH₄ budget identified the study field (6.53 ha) as CH₄ source (40.9 kg C ha⁻¹ a⁻¹). Not only CH₄ emissions, but also dissolved CH₄ in soil solution varied regularly with soil type. Individual soil solutions contained 0.008–151 μmol CH₄ l⁻¹. CH₄ vanished to negligible loads, when dissolved CH₄ passed an oxidative downslope soil zone, but promoted CH₄ uptake was measured at this soil. In turn, CH₄ was discharged to the atmosphere, when the soil solution left the pedosphere across an anaerobic soil zone. These measured indirect emissions were low (34 g C a⁻¹), but the values of individual soil solution indicate possible higher discharges (3.9 kg a⁻¹) at a different soil pattern. The results suggest that CH₄ uptake rates of temperate forests are overestimated.     

Seasonal changes in canopy photosynthesis and foliage respiration in a Rhizophora stylosa stand at the northern limit of its natural distribution

Gross photosynthesis and respiration rates of leaves at different canopy heights in a Rhizophora stylosa Griff. stand were measured monthly over 1 year at Manko Wetland, Okinawa Island, Japan, which is the northern limit of its distribution. The light-saturated net photosynthesis rate for the leaves at the top of the canopy showed a maximum value of 17 μmol CO₂ m⁻² s⁻¹ in warm season and a minimum value of 6 μmol CO₂ m⁻² s⁻¹ in cold season. The light-saturated gross photosynthesis and dark respiration rates of the leaves existing at the top of the canopy were 2−7 times and 3–16 times, respectively, those of leaves at the bottom of the canopy throughout the year. The light compensation point of leaves showed maximum and minimum peaks in warm season and cold season, respectively. The annual canopy gross photosynthesis, foliage respiration, and surplus production were estimated as 117, 49, and 68 t CO₂ ha⁻¹ year⁻¹, respectively. The energy efficiency of the annual canopy gross photosynthesis was 2.5%. The gross primary production GPP fell near the regression curve of GPP on the product of leaf area index and warmth index, the regression curve which was established for forests in the Western Pacific with humid climates.     

Photosynthetically versatile thin shade leaves: A paradox of irradiance-response curves

Thick sun leaves have a larger construction cost per unit leaf area than thin shade leaves. To re-evaluate the adaptive roles of sun and shade leaves, we compared the photosynthetic benefits relative to the construction cost of the leaves. We drew photosynthetically active radiation (PAR)-response curves using the leaf-mass-based photosynthetic rate to reflect the cost. The dark respiration rates of the sun and shade leaves of mulberry (Morus bombycis Koidzumi) seedlings did not differ significantly. At irradiances below 250 μmol m⁻² s⁻¹, the shade leaves tended to have a significantly larger net photosynthetic rate (P _N) than the sun leaves. At irradiances above 250 μmol m⁻² s⁻¹, the P _N did not differ significantly. The curves indicate that plants with thin shade leaves have a larger daily CO₂ assimilation rate per construction cost than those with thick sun leaves, even in an open habitat. These results are consistently explained by a simple model of PAR extinction in a leaf. We must target factors other than the effective assimilation when we consider the adaptive roles of thick sun leaves.     

Estimation of carbon storage, carbon inputs, and soil CO2 efflux of alder plantations on granite soil in central Korea: comparison with Japanese larch plantation

Alder is a typical species used for forest rehabilitation after disturbances because of its N₂-fixing activities through microbes. To investigate forest dynamics of the carbon budget, we determined the aboveground and soil carbon content, carbon input by litterfall to belowground, and soil CO₂ efflux over 2 years in 38-year-old alder plantations in central Korea. The estimated aboveground carbon storage and increment were 47.39 Mg C ha⁻¹ and 2.17 Mg C ha⁻¹ year⁻¹. Carbon storage in the organic layer and in mineral soil in the topsoil to 30 cm depth were, respectively, 3.21 and 66.85 Mg C ha⁻¹. Annual carbon input by leaves and total litter in the study stand were, respectively, 1.78 and 2.68 Mg C ha⁻¹ year⁻¹. The aboveground carbon increment at this stand was similar to the annual carbon inputs by total litterfall. The diurnal pattern of soil CO₂ efflux was significantly different in May, August, and October, typically varying approximately twofold throughout the course of a day. In the seasonally observed pattern, soil CO₂ efflux varied strongly with soil temperature; increasing trends were evident during the early growing season, with sustained high rates from mid May through late October. Soil CO₂ efflux was related exponentially to soil temperature (R ² = 0.85, P < 0.0001), but not to soil water content. The Q ₁₀ value for this plantation was 3.8, and annual soil respiration was estimated at 10.2 Mg C ha⁻¹ year⁻¹. An erratum to this article can be found at