Utilization and traditional strategies of in situ conservation of iroko (Milicia excelsa Welw. C.C. Berg) in Benin

Socio-cultural surveys were carried out on the basis of a questionnaire administered on 346 respondents in order to investigate cultural and ethnobotanic uses of Milicia excelsa in Benin.M. excelsa contributes to cure 45 human diseases. The different parts of the tree used are leaves (30.3%), bark (25.8%), root (23.6%), latex (10.1%), flaking bark (6.7%), wood, calcium concentrated in old trees, and gum (1.1% each). Fruits or seeds are rarely used. Six different forms of utilization were recorded: soaking (46.3%), bark or leaves decoction (32.8%), herb tea (11.9%), powder (6.0%), leaves or bark grounded and rolled up into ball (1.5%), component of offering to fetish (1.5%). Iroko wood is also used in carpentry and joinery for construction purposes; furniture as well as for building boats/canoes.Iroko tree is used as the conservatory of cultural values and incarnates many divinities, which differ significantly from one province to another (χ² = 1830.27; d.f. = 25; P < 0.01%). There is a significant difference between the provinces in respect of the recognition of the species (χ² = 268.71; d.f. = 17; P ≤ 0.01%) and the population awareness about iroko as a sacred tree also varied from one province to another (χ² = 308.66; d.f. = 27; P ≤ 0.01%).Veneration of the tree is the main approach of its conservation by local people. M. excelsa is conserved on farm, in sacred groves, in public places and in cemeteries. The different sacred objects used to symbolize the divinities incarnated by iroko are: pottery (36.36%), iron (11.11%), calabash (4.04%), candle (2.02%), piece of cloth (18.18%), sacrifice (13.13%), piece of money (3.0%), stone (2.05%), glassware (broken bottle, 2.02%), and convent (8.08%). There is a highly significant difference between provinces as far as the sacred objects are concerned (χ² = 183.037; d.f. = 19 and P < 0.001%). The conservation purposes also vary significantly from one region to other (χ² = 894.47; d.f. = 31; P < 0.01%).     

Population structure and nut yield of a Bertholletia excelsa stand in Southwestern Amazonia

Although Brazil nut (B. excelsa) is often touted as one of the most economically successful NTFPs, little is known about the population structure of this species within its natural range in Southwestern Amazonia or ecological factors that affect fruit production. Since these are considered fundamental for sustainable resource management, we examined a natural Brazil nut stand in an extractive reserve in Acre, Brazil, posing the following questions: (1) What is the spatial distribution, species density, and size–class structure of B. excelsa? and (2) What tree-level factors influence Brazil nut production? In a 420 ha census, 568 trees ≥10 cm diameter at breast height (dbh) were counted, resulting in a density of 1.35 trees ha⁻¹. Based on the nearest-neighbor method, an index of aggregation (R) of 0.77 indicated a rejection of the null hypothesis of a strictly random distribution pattern. Yet, this value suggests a much greater tendency toward randomness than either clumping or uniformity. Our data do not show the commonly reported existence of groves, referring to clearly defined clusters of 50 to several hundred trees separated from similar clusters by great distances. Almost 1/4 of the population (23%) was composed of non-reproductive juveniles. Maximum R² improvement analysis applied to four distinct diameter classes provided insight into the dynamics of production-related variables over the species life cycle. While dbh explained 1/3 of production variance (R² = 0.3360) in the smallest diameter class (10 cm ≤ dbh < 50 cm), which included those in the process of reaching reproductive maturity, crown form best explained production variance of very large trees (dbh ≥ 100 cm). Results also demonstrated a significant negative correlation between crown vine load and production of trees ≥ 50 cm dbh (r = −0.13, P = 0.008), suggesting the need for further study on vine cutting as a possible silvicultural treatment for enhancing nut yields.     

Can intensive management accelerate the restoration of Brazil's Atlantic forests?

Only 7% of the once extensive forest along the eastern coast of Brazil remains, and much of that is degraded and threatened by agricultural expansion and urbanization. We wondered if methods similar to those developed to establish fast-growing Eucalyptus plantations might also work to enhance survival and growth of rainforest species on degraded pastures composed of highly competitive C₄ grasses. An 8-factor experiment was laid out to contrast the value of different intensities of cultivation, application of fertilizer and weed control on the growth and survival of a mixture of 20 rainforest species planted at two densities: 3 m × 1 m, and 3 m × 2 m. Intensive management increased seedling survival from 90% to 98%, stemwood production and leaf area index (LAI) by ～4-fold, and stemwood production per unit of light absorbed by 30%. Annual growth in stem biomass was closely related to LAI alone (r² = 0.93, p < 0.0001), and the regression improved further in combination with canopy nitrogen content (r² = 0.99, p < 0.0001). Intensive management resulted in a nearly closed forest canopy in less than 4 years, and offers a practical means to establish functional forests on abandoned agricultural land.     

Production,allocation, and stemwood growth efficiency of Pinus taeda L. stands in response to 6 years of intensive management

Loblolly pine (Pinus taeda L.) is a highly plastic species with respect to growth responses to forest management. Loblolly pine is the most planted species across the southern United States, a region with the most expansive and intensively managed forest plantations in the world. Management intensity, using tools such as site preparation and fertilization, is increasing greatly in scope over time. To better define to the productive potential of loblolly pine under intensive management, the influence of 6 years of management with weed control (W), weed control plus irrigation (WI), weed control plus irrigation and fertigation (irrigation with a fertilizer solution) (WIF), or weed control plus irrigation, fertigation, and pest control (WIFP) since plantation establishment on stand productivity in loblolly pine was examined. The site is located near Bainbridge, GA (30°48′N latitude and 84°39′W longitude) and is of medium quality (site index=18 m, base age 25). Increasing management intensity greatly accelerated stand development and biomass accumulation. At age 6 total production (above plus belowground) was nearly doubled from 50 to 93 Mg ha⁻¹ in WIFP stands compared to W stands, and standing stem biomass increased from 24 Mg ha⁻¹ in W stands to 48 Mg ha⁻¹ in response to WIFP treatment. Stem current annual increment (CAI) peaked at age 5 in the WIF and WIFP stands at 17–18 Mg ha⁻¹ per year at a basal area between 18 and 21 m² ha⁻¹. Year to year variation in CAI was better explained by previous-year leaf area index (LAI) than current-year LAI. Maximum stemwood production in loblolly pine was achieved through large increases in LAI and small decreases in allocation to woody roots (tap+coarse roots) versus woody shoots (stem+branches) associated with intensive treatments.     

Dynamics of above- and below-ground biomass and nutrient accumulation in an age sequence of Nothofagus antarctica forest of Southern Patagonia

Nothofagus antarctica (Forster f.) Oersted is a deciduous tree species, which naturally grows on poorly drained or drier eastern sites in the Andes Mountain near Patagonian steppe. Above- and below-ground biomass and nutrients pools were measured in pure even-aged stands at different ages (5–220 years) and crown classes. Functions were fitted for total biomass and nutrients accumulation, and root/shoot ratio of individual trees against age. Total biomass accumulated for mature dominant trees was eight times greater than mature suppressed trees. Biomass root/shoot ratio decreased with age from 1.8 to a steady-state of 0.5. All nutrients concentration (except Ca) decreased with age and varied according to the degree of crown suppression classes. Nutrient concentrations varied between biomass pool components following the order leaves > bark > small branches > fine roots > medium roots > rooten wood > coarse roots > sapwood > heartwood. Total nutrient accumulation followed the order dominant > codominant > intermediate > suppressed trees and its accumulation rate varied over time, e.g. P accumulation rate of dominant trees increased from 0.17 g tree⁻¹ year⁻¹ during regeneration to 1.39 g tree⁻¹ year⁻¹ in mature trees. Nutrients uptake reached a peak during the period of maximum biomass production, and root/shoot ratio of nutrients decreased from its maximum value at 5 years of age (0.6, 4.0, 0.9, 1.5, 1.0 and 2.6 for N, P, K, Ca, S and Mg, respectively) to a steady-state asymptote beyond 50 years of age. Thus, accumulation of nutrients in roots was greater during the regeneration phase of stand development, and nutrient accumulation increased in above-ground over time. Also, nutrient use efficiency increased in mature trees (111–220 years) and decreased in suppressed crown classes. The equations developed for individual trees have been used to estimate stand biomass and nutrient accumulation from forest inventories data. Total stand biomass varied from 62.5 to 133.4 t ha⁻¹ and total nutrients accumulation ranged from 3 kg Mg ha⁻¹ to 1235 kg Ca ha⁻¹. Proposed equations can be used for practical purposes such as to estimate pasture nutrients requirement in a silvopastoral system based on nutrients supply from leaf litter returns, or to determine amelioration practices like debarking stems before harvesting.     

Wood density of trees in open savannas of the Brazilian Amazon

Studies on basic density of woody species in Amazonian savannas are needed to convert data on woody volume to biomass. These ecosystems, which have large carbon stocks, emit greenhouse gases annually due to frequent burnings. Basic density (g cm⁻³: oven-dry weight/wet volume), measured from complete sample disks (bark, sapwood and heartwood), was calculated for the most abundant woody species in three types of open savannas (Sg: grassy-woody savanna; Sp: savanna parkland; Tp: steppe-like parkland) in Roraima, a state in the northern part of Brazil’s Amazon region. The species selected represent 90–95% of the woody biomass estimated in these ecosystem types. Seven additional species were lumped in an “others” group. In total, we sampled 107 trees: 40 in Sg, 37 in Sp and 30 in Tp. Bowdichia virgilioides (0.516 ± 0.021 (S.E.) g cm⁻³) was the species with the highest basic density, followed by the “others” group (0.485 ± 0.057 g cm⁻³), Curatella americana (0.413 ± 0.028 g cm⁻³), Byrsonima crassifolia + B. coccolobifolia (0.394 ± 0.019 g cm⁻³), Himatanthus articulatus (0.375 ± 0.020 g cm⁻³) and B. verbascifolia (0.332 ± 0.020 g cm⁻³). Basic density of the species with the greatest woody biomass in Roraima’s open savannas (C. americana and B. crassifolia + B. coccolobifolia) did not differ significantly at the 5% level (ANOVA) among the three ecosystem types studied. Wood basic density in these savannas (weighted mean = 0.404 ± 0.025 g cm⁻³) is lower than that in Amazonian forests (weighted mean = 0.680 g cm⁻³). These results reduce uncertainty in calculations of carbon stocks and of greenhouse gas emissions from clearing and burning tropical savanna.     

Mineral nitrogen dynamics following soil compaction and cultivation during hoop pine plantation establishment

The effects of soil compaction and cultivation on soil mineral N dynamics were investigated through an 18-month, in situ N mineralisation experiment during the inter-rotation and early establishment period of a second rotation (2R) hoop pine (Araucaria cunninghamii Aiton ex A. Cunn) plantation in southeast Queensland, Australia. Treatments were 0, 1 and 16 passes of a fully laden forwarder (gross weight, 40.2 Mg) and cultivation by disc plough (zero cultivation and cultivation). Nitrate N was the dominant form of mineral N throughout the 18-month sampling period in both non-cultivated and cultivated soils, varying between 10 and 40 kg ha⁻¹ whilst ammonium N remained <10 kg ha⁻¹. Compaction had no significant effect on N mineralisation or nitrification. However, the remediation of the effects of compaction on soil through the use of the disc plough had significant impacts on N mineralisation, nitrification and N leaching. On a seasonal basis, the mean net N mineralisation increased from around 30 to 53 kg ha⁻¹, nitrification from 28 to 43 kg ha⁻¹ and nitrate N leaching from around 10 to 73 kg ha⁻¹ following cultivation.     

Litter production and organic matter accumulation in exclosures of the Tigray highlands,Ethiopia

To determine annual litter production of regenerating forest areas in the Tigray highlands of northern Ethiopia monthly litter production was monitored over a two-year period in areas with varying degree of vegetation cover restoration. Total annual litter production varied from 30 to 425 g m⁻² and increased significantly where areas were closed for a longer time. Litter production was depending on vegetation cover through an exponential relation and was influenced also by soil fertility. Leaf litter typically constituted between 70 and 85% of total litter production, while contributions of woody and reproductive litter varied according to species composition. Strong seasonality in litterfall was explained by pronounced seasonal variation in rainfall. Standing crop of litter built up once an area was closed for grazing, increasing from around 20 g m⁻² in degraded grazing lands to nearly 600 g m⁻² in an old exclosure. Litter accumulation was mainly determined by litter input, but was also influenced by litter quality, species composition and microclimate development in the restoring forest areas. A detailed study of nine dominant shrub and tree species revealed three distinct litter production patterns, corresponding to drought-deciduous species, evergreen species and (semi-)evergreen Acacia species respectively.     

Estimation of biomass and net primary productivity of major planted forests in China based on forest inventory data

Reforestation and afforestation have been suggested as an important land use management in mitigating the increase in atmospheric CO₂ concentration under Kyoto Protocol of UN Framework Convention on climate change. Forest inventory data (FID) are important resources for understanding the dynamics of forest biomass, net primary productivity (NPP) and carbon cycling at landscape and regional scales. In this study, more than 300 data sets of biomass, volume, NPP and stand age for five planted forest types in China (Larix, Pinus tabulaeformis, Pinus massoniana, Cunninghamia lanceolata, Pouulus) from literatures were synthesized to develop regression equations between biomass and volume, and between NPP and biomass, and stand age. Based on the fourth FID (1989–1993), biomass and NPP of five planted forest types in China were estimated. The results showed that total biomass and total NPP of the five types of forest plantations were 2.81 Pg (1 Pg = 10¹⁵ g) and 235.65 Mg ha⁻¹ yr⁻¹ (1 Mg = 10⁶ g), respectively. The area-weighted mean biomass density (biomass) and NPP of different forest types varied from 44.43 (P. massoniana) to 146.05 Mg ha⁻¹ (P. tabulaeformis) and from 4.41 (P. massoniana) to 7.33 Mg ha⁻¹ yr⁻¹ (Populus), respectively. The biomass and NPP of the five planted forest types were not distributed evenly across different regions in China. Larix forests have the greatest variations in biomass and NPP, ranging from 2.7 to 135.37 Mg ha⁻¹ and 0.9 to 10.3 Mg ha⁻¹ yr⁻¹, respectively. However, biomass and NPP of Populus forests in different region varied less and they were approximately 50 Mg ha⁻¹ and 7–8 Mg ha⁻¹ yr⁻¹, respectively. The distribution pattern of biomass and NPP of different forest types closely related with stand ages and regions. The study provided not only with an estimation biomass and NPP of major planted forests in China but also with a useful methodology for estimating forest carbon storage at regional and global levels.     

Nutrient uptake and growth of young trees in a P-deficient soil: Tree species and phosphorus effects

Phosphorus deficiency is widespread in the subhumid highlands of eastern Africa but there are few data on the effect of P deficiency on the growth of agroforestry tree species. We studied the effect of P application on growth, nutrient uptake and dry matter partitioning in young trees of Calliandra calothyrsus, Cedrela serrulata, Eucalyptus grandis, Grevillea robusta, Markhamia lutea, Senna spectabilis, and Sesbania sesban on a P-deficient soil (Kandiudalfic Eutrudox, bicarbonate-EDTA extractable P = 1 mg kg⁻¹) in western Kenya. The trees were grown at two P levels (control and 500 kg added P ha⁻¹) at 1 m² spacing in a randomized complete block design with three replications. Leaf K concentrations were in the low range for all species (5–9 mg g⁻¹) and K deficiency may have limited responses to P. Averaged over species, P addition increased aboveground shoot dry matter by a factor of 2.6 at 62 and 124 days, but the response decreased to 1.3 at 325 days. The increases at 62 days were large in sesbania (5.4) and eucalyptus (3.2) but small in calliandra (1.4) and markhamia (1.1). Relative response to P was more strongly correlated with shoot growth rate per unit root length among species than with shoot growth rate alone. Calliandra, which had high early growth rate but low response to added P, had an exceptionally high root length (6.0 km m⁻²) compared with the other species (0.3–2.1 km m⁻²). P addition increased N and P content but decreased final shoot K content in sesbania and calliandra, and had little effect on K content in the other species. The high-yielding species (eucalyptus, sesbania and calliandra) accumulated more than 30 g N and 2 g P m⁻² in shoots in 325 days of growth. The proportion of total shoot N in wood (branch + stem) was in a higher range (67–75%) in the shrubby species (sesbania, calliandra, senna) than in the upperstorey tree species (38–43%). Slow early shoot growth relative to total root length, and high specific root length (root length per unit root mass) are proposed as criteria for the selection of species and provenances that are well adapted to P deficient soils.     

Carbon sources and sinks in high-elevation spruce–fir forests of the Southeastern US

This paper examines carbon (C) pools, fluxes, and net ecosystem balance for a high-elevation red spruce–Fraser fir forest [Picea rubens Sarg./Abies fraseri (Pursh.) Poir.] in the Great Smoky Mountains National Park (GSMNP), based on measurements in fifty-four 20 m × 20 m permanent plots located between 1525 and 1970 m elevation. Forest floor and mineral soil C was determined from destructive sampling of the O horizon and incremental soil cores (to a depth of 50 cm) in each plot. Overstory C pools and net C sequestration in live trees was estimated from periodic inventories between 1993 and 2003. The CO₂ release from standing and downed wood was based on biomass and C concentration estimates and published decomposition constants by decay class and species. Soil respiration was measured in situ between 2002 and 2004 in a subset of eight plots along an elevation gradient. Litterfall was collected from a total of 16 plots over a 2–5-year period.The forest contained on average 403 Mg C ha⁻¹, almost half of which stored belowground. Live trees, predominantly spruce, represented a large but highly variable C pool (mean: 126 Mg C ha⁻¹, CV = 39%); while dead wood (61 Mg C ha⁻¹), mostly fir, accounted for as much as 15% of total ecosystem C. The 10-year mean C sequestration in living trees was 2700 kg C ha⁻¹ year⁻¹, but increased from 2180 kg C ha⁻¹ year⁻¹ in 1993–1998 to 3110 kg C ha⁻¹ year⁻¹ in 1998–2003, especially at higher elevations. Dead wood also increased during that period, releasing on average 1600 kg C ha⁻¹ year⁻¹. Estimated net soil C efflux ranged between 1000 and 1450 kg C ha⁻¹ year⁻¹, depending on the calculation of total belowground C allocation. Based on current flux estimates, this old-growth system was close to C neutral.     

Long-term growth and ecophysiological responses of a southeastern Oklahoma loblolly pine plantation to early rotation thinning

A thinning levels study was initiated in a 9-year-old loblolly pine (Pinus taeda L.) plantation containing 26.6 m² ha⁻¹ basal area during the spring of 1984 in southeastern Oklahoma. Thinning treatments consisted of (1) three control plots (BA100), (2) three plots thinned to approximately 50% of the original basal area (BA50) and (3) three plots that were thinned to 25% of the original basal area (BA25). In 1987 the BA50 and BA25 plots were both rethinned to a basal area of 12 m² ha⁻¹. No other thinnings were done through age 24.The control plots have attained a basal area of 45.3 m² ha⁻¹ and basal area is now starting to decline. The BA25 and BA50 plots have basal areas between 34 and 35 m² ha⁻¹. Mortality has averaged about 90 trees ha⁻¹ per year from age 10 to age 24 on the control plot, declining from 2078 trees ha⁻¹ at age 10 to 827 trees ha⁻¹ at age 24. Mortality losses in the BA25 and BA50 plots have been only 3.2–7.7 trees ha⁻¹ per year over the entire study period. Cumulative stem biomass lost to mortality was 10.5, 16.0 and 61 Mg ha⁻¹, respectively, for the BA25, BA50 and BA100 treatments. Cumulative standing live biomass at age 24 in the BA100 treatment is 132 Mg ha⁻¹. Cumulative standing live biomass in the BA25 and BA50 treatments at age 24 is 86 and 79%, respectively, of that observed in the BA100 treatment. These results suggest wide ranges of residual stand densities left after an early thinning will produce a high percentage of the potential total maximum standing stem biomass. Diameter distributions at age 24 show only 33% of the trees in the BA100 treatments have the dimensions to be sawtimber (≥30 cm) but 92 and 95% of the trees in the BA25 and BA50, respectively, are sawtimber dimension or larger. Mean annual stem biomass production (MAI) of the BA100 treatment is 7.5 Mg ha⁻¹ per year at age 24. MAI of the thinned treatments is about 5.1 Mg ha⁻¹ per year and is converging to that of the BA100 treatment. The basis for this convergence is not that the live trees in the BA100 treatment are producing live biomass less rapidly than the thinned plots, but that mortality losses in the BA100 plot are much higher. Current annual stemwood production in all treatments is often limited by the severe summer droughts that occur in this region. The wide variations in weather experienced at this site also result in variations in earlywood:latewood ratio and ring specific gravity.     

Fine-root distribution and morphology in an acidic Norway spruce (Picea abies (L.) Karst.) stand in SW Sweden in relation to granulated wood ash application

Wood ash is recommended as a compensatory fertiliser to counteract the effects of acidic deposition on forest ecosystems. Spatial distribution of biomass, necromass and morphology parameters of the fine roots (diameter classes <1, 1–2, <2 mm) of Norway spruce (Picea abies (L.) Karst.) were analysed in response to fertilisation with granulated wood ash (GWA) in a long-term field experiment in SW Sweden. GWA was applied as a single dose of 3200 kg ha⁻¹ and the fine roots were sampled 9 years later by soil coring. Soil cores were divided into 1-cm strata within the top 0–2.5 cm humus limits, the lower humus below 2.5 cm (with varying thickness) and the mineral soil to 50 cm depth (from ground surface). Total fine-root biomass in the control (C) and GWA treatment, 256 ± 20 and 258 ± 25 g m⁻², respectively, and length 2072 ± 182 and 1800 ± 198 m m⁻², respectively, did not differ statistically from each other. Total fine-root necromass in the 1–2 mm fraction was significantly higher in C than in the GWA treatment, 130 ± 12 and 80 ± 10 g m⁻², respectively. Fine-root biomass in the <1 mm fraction was significantly greater in the lower humus in the GWA treatment, but this did not affect the total biomass in the <1 mm fraction in the whole soil profile. The biomass-to-necromass ratio (1–2 mm) was significantly higher in the GWA treatment in the 0–30 cm soil layer than in the corresponding layer of the control. Specific root length (SRL) was lower in the GWA treatment than in the control in the 0–5 cm soil layer. The lower necromass and SRL were more clearly related to the GWA treatment, whereas the difference in the vertical distribution of biomass may have been related to the thicker humus layer in the GWA plots.     

Stand development after different thinnings in two uneven-aged Picea abies forests in Sweden

Two field experiments, located in Central and Northern Sweden, were used to study the influence of standing volume on volume increment and ingrowth in uneven-aged Norway spruce (Picea abies (L.) Karst.) stands subjected to different thinnings. Each experiment had a 3 × 2 factorial block design with two replications. Treatments were thinning grade, removing about 45, 65, and 85% of pre-thinning basal area, and thinning type, removing the larger or the smaller trees, respectively. Each site also had two untreated control plots. Plot size was 0.25 ha. Volume increment was 0.5–6.8 m³ ha⁻¹ year⁻¹ for the plots, and significantly positively (p < 0.01) correlated with standing volume. Within treatment pairs, plots thinned from Above had consistently higher volume increment than plots thinned from Below. Ingrowth ranged from 3 to 33 stems ha⁻¹ year⁻¹, with an average of 14 and 21 stems ha⁻¹ year⁻¹ at the northern and southern site, respectively. At the southern site ingrowth was significantly negatively (p < 0.01) correlated with standing volume, but not at the northern site. Mean annual mortality after thinning was 2 and 7 stems ha⁻¹ year⁻¹at the northern and southern site, respectively.     

The analyses of physiological and morphological attributes of 10 tree species for early determination of their suitability to afforest degraded landscapes in the Aral Sea Basin of Uzbekistan

The establishment of woody fallow systems is an option for the improvement of degraded agricultural landscape within the ecologically deteriorated Aral Sea area in northwest Uzbekistan. Growth and development of ten tree species, differing in tolerance to drought and salinity, were studied over 24 months. To determine species suitability for afforestation, conventional diameter and height measurements were compared to Relative Growth Rate (RGR) and its underlying components, Net Assimilation Rate (NAR), Specific Leaf Area (SLA) and Leaf Weight Ratio (LWR), as well as the Crop Growth Rate (CGR) as a function of NAR and Leaf Area Index (LAI). RGRs varied between 0.46 and 2.16 mg g⁻¹ day⁻¹ and showed highly significant differences among species, but also between years, which reduces the parameter's suitability for species selection. The same is true for NAR and SLA. CGR values ranged from 0.01 to 0.71 g m⁻² day⁻¹, increased with age of the trees, and showed significant species differences. CGR correlated better with NAR (r = 0.89) and SLA (r = 0.86) than RGR. Overall CGR correlated highly with the RGRs in height and diameter (in 80% and 71% of all cases, respectively). Thus, CGR appears to be a suitable indicator complementing RGR, NAR and SLA estimates to decide on species suitability for afforestation. The intensive measurements for RGR should be done later, rather than earlier in the tree life cycle. At an early age, CGR and diameter measurements are more meaningful. A combination of estimates, not a single factor, best assesses the long-term sustainable growth under natural conditions and allows early selection of species suitable for afforestation of degraded patches in the agricultural landscape. Ranking of all parameters concurrently showed the high potential of Elaeagnus angustifolia and Populus euphratica, which matched previous rankings based on total biomass production and financial added value.     

Biomass and nutrient accumulation in pure and mixed plantations of indigenous tree species grown on poor soils in the humid tropics of Costa Rica

Aboveground biomass and nutrients and soil chemical characteristics were examined in young plantations of four indigenous tree species: Hieronyma alchorneoides, Vochysia ferruginea, Pithecellobium elegans, and Genipa americana, growing in mixed and pure stands at La Selva Biological Station, Costa Rica. Total tree biomass production rates ranged from about 5.2 Mg ha⁻¹ year⁻¹ for G. americana to 10.3 Mg ha⁻¹ year⁻¹ for H. alchorneoides pure stands, and for the species mixture it was about 8.9 Mg ha⁻¹ year⁻¹. Branches and foliage formed 25–35% of total tree biomass but they represented about 50% of total tree nutrients. H. alchorneoides, the four species mixture, and P. elegans had the greatest accumulations of total aboveground nutrients per hectare. The importance of the plantation floor as a nutrient compartment varied temporally. When forest floor litter biomass was at its peak, plantation floor litter N, Ca, and Mg were roughly equal to, or greater than stem nutrients for all species except for P. elegans. For P. elegans, the plantation floor consistently represented a very low proportion of total aboveground nutrients. G. americana and V. ferruginea trees showed 55–60% less biomass accumulation in mixed than in pure stands while H. alchorneoides and P. elegans trees grew 40–50% more rapidly in mixture. P. elegans foliage had 60% lower Ca but higher P concentrations in mixed than in pure stands, and G. americana had higher foliar Mg in mixed than in pure stands. V. ferruginea stands had the highest concentrations of soil Ca, Mg, and organic matter, particularly in the top layers. Relative to pure plantations, soil nutrient concentrations in mixed plantations were intermediate for N, P, and K, but lower for Ca and Mg. The results of this study can be used in the selection of tree species and harvest designs to favor productivity and nutrient conservation.     

Profitability potential for Pinus taeda L. (loblolly pine) short-rotation bioenergy plantings in the southern USA

The use of renewable resources is important to the developing bioenergy economy and short rotation woody crops (SRWC) are key renewable feedstocks. A necessary step in advancing SRWC is defining regions suitable for SRWC commercial activities and assessing the relative economic viability among suitable regions. The goal of this study was to assess the potential profitability, based on obtainable yield and economic feasibility; of Pinus taeda L. (loblolly pine) across 13 states of the southern USA. A process-based growth model, 3PG, produced estimated yields of P. taeda in terms of mean annual increment (MAI) that were evaluated as internal rate of return on investment (IRR) and land expectation value (LEV). Coastal areas (southeast Texas, southwest Louisiana, and northern Florida) have the highest potential MAI production ranging from 13.7 to 18.9 Mg ha^− 1 yr^− 1. LEVs ranged from − 1126 to 3111 $ ha^− 1 on upland sites and − 2261 to 2341 $ ha^− 1 on lowland sites. IRR ranged from − 0.3% to 14.2% on uplands and − 2.9% to 10.4% on lowlands. On soils of the same textural class, LEV and IRR were higher on uplands relative to lowlands given lower site preparation costs, although the projected yield from upland soils are generally lower than those from lowland soils. The highest LEV and IRR were in northern Florida, southern Alabama, southern Georgia, and southern South Carolina. The lowest LEV and IRR were in Virginia and northern North Carolina. Spatially categorizing suitable lands in biological and economic terms can use geographic information system technology to advantage in combination with societal considerations to begin to answer sustainability questions as well as identify suitable sites for bioenergy plantations.     

New lignans from the bioactive fraction of Sambucus williamsii Hance and proliferation activities on osteoblastic-like UMR106 cells

Four new lignans (1, 7–9), together with nine known ones, were isolated from the anti-osteoporosis fraction of the extract of Sambucus williamsii Hance which was eluted by 50% and 95% aqueous ethanol over D101 macroporous resin column. Their structures were elucidated by NMR spectroscopic analyses, and the absolute configurations of all compounds were determined by application of circular dichroism method. All the compounds were reported for the first time from the Sambucus genus and firstly studied for their proliferation effects on osteoblastic-like UMR 106 cell. The data showed that compounds 2–9 significantly promoted cell proliferation in some dose, especially compounds 2, 3, 4, 5, and 7 increased osteoblastic cell numbers by 31.3%, 28.3%, 25.6%, 25.1% and 26.0% at 10^− 10 M, 10^− 10 M, 10^− 7 M, 10^− 10 M and 10^− 10 M, respectively, which suggested that lignans were the components accounting for the bone protective effects of SWH.     

A comprehensive analysis of teak plantation investment in Colombia

A financial assessment of forest investments is comprehensive if the analysis includes reliable yield estimates, land expectation value (LEV) and risk calculation. All of these aspects were considered and applied to teak plantations in Colombia, an emergent economy where high forest productivity, low opportunity cost of land, and decreased financial/economic risk have substantially contributed to promote forest investments. The von Bertalanffy non-linear mixed effect model was used to estimate forest yields using data collected from 31 permanent sample plots, measured over a 17 year period. A stochastic version of LEV along with other financial criteria was calculated by using a computer algorithm and Monte Carlo simulation. Finally, probabilities obtained from stochastic financial calculations were used in logistic models to estimate probabilities of success for a forest plantation project, a measure of risk assessment, after changing land prices. Results suggest that the potential forest productivity (i.e., the biological asymptote) ranges from 93 to 372 m³ ha^− 1. The mean annual increment is 27.8 m³ ha^− 1 year^− 1, which is attained 6 years after the forest plantation is established. Profitability analyses for teak plantations in Colombia suggest a LEV of US$7000 ha^− 1. The risk analyses indicate negligible financial risk for forestlands whose prices are lower than US$2000 ha^− 1.     

Distribution,colonization and diversity of arbuscular mycorrhizal fungi associated with central Himalayan rhododendrons

The objective of the present study was to investigate arbuscular mycorrhizal status of five species of rhododendrons distributed in Kumaun region of the Indian Central Himalaya. Root and rhizosphere soil samples of all the five species of rhododendrons, namely, Rhododendron anthopogon, R. arboreum, R. campanulatum, R. barbatum and R. lepidotum were collected from temperate, sub-alpine to alpine location in altitudinal range from 1500 to 4500 m amsl. The arbuscular mycorrhizal colonization in root samples ranged from 28 to 42%; and maximum and minimum colonization was observed in R. arboreum and R. lepidotum, respectively. The highest number of intraradical vesicles (12.5 ± 2.8 cm⁻¹ root segment) was recorded in R. arboreum and the lowest (7.0 ± 1.7 cm⁻¹ root segment) in R. barbatum; vesicles were not observed in R. lepidotum. Spores were extracted from the rhizosphere soil by wet sieving to perform microscopic identification of the species. The maximum and minimum populations of spores were detected in the rhizosphere soil samples of R. anthopogon (52.0 ± 1.5 spores 25 g⁻¹ soil) and R. lepidotum (32.0 ± 2.5 spore 25 g⁻¹ soil), respectively. Spore populations were found to belong to five genera—Acaulospora, Glomus, Gigaspora, Sclerocystis and Scutellispora; genus Glomus was found to be dominant in the rhizosphere soil samples of all the rhododendron species. The most frequent and abundant species was G. fasciculatum, however, this species was not isolated from the rhizosphere soil of R. barbatum. Finger millet (Eleucine coracana) was used to cultivate the trap culture of arbuscular mycorrhizal fungi to confirm the species identity. Spores of Glomus pustulatum, not detected in the rhizosphere soil, were recovered from the trap culture. Contrary to this, genus Gigaspora, which was present in the rhizosphere soil, did not sporulate in the trap culture. Shannon and Wiener index of diversity and Simpson's index of dominance indicated that the species richness, dominance and diversity of arbuscular mycorrhizal fungi decrease with increasing altitude. In two species of rhododendrons, namely R. campanulatum and R. anthopogon, dark septate mycelium was also observed.