Long-term estimates of live above-ground tree carbon stocks and net change in managed uneven-aged mixed species forests of sub-tropical Queensland,Australia

Estimates of carbon stocks and their annual change for extensive Australian sub-tropical forests are based on indirect estimates or on data derived from temperate forests. We estimated live above-ground tree carbon (LAC) stocks at landscape level from 355?000 measurements of 94?127 tree stems from 604 permanently monitored plots representing 2.6 million ha of managed uneven-aged mixed-species native forests in sub-tropical Queensland. These plots were established between 1936 and 1998 and re-measured every 2 to 10 years up to 2011. Landscapes were represented by 16 broad vegetation groups growing across a mean annual rainfall range of 500 to 2000 mm. Landscape-mean LAC stocks varied from 20.8 ± 4.3 t C ha^?1 in inland eucalypt woodlands to 146.4 ± 11.1 t C ha^?1 in coastal wet tall open forests. Landscape maximum LAC stock, defined as the mean of maximum LAC stocks over the entire measurement history for a specified landscape under prevailing environmental conditions and disturbance regimes, including sustainable forest management, ranged from 34.0 ± 7.2 t C ha^?1 in inland eucalypt woodlands to 154.9 ± 19.4 t C ha^?1 in coastal wet tall open forests. Annual live above-ground net carbon flux (C-flux) across all forests types ranged from 0.46 to 2.92 t C ha^?1 y^?1 with an overall mean of 0.95 t C ha^?1 y^?1 (n = 2067). Comparison of our results with Intergovernmental Panel on Climate Change (IPCC) estimates shows that in all cases, except for the sub-tropical steppe, the IPCC over-estimated stocks by between 13% and 34%. Conversely, the IPCC estimated C-fluxes were between 14% and 40% less than the Queensland estimates. These results extend statistically valid estimates of landscape LAC stocks and fluxes to the sub-tropical regions of Australia.     

Effects of Resource Conservation Practices on Productivity,Profitability and Energy Budgeting in Maize–Wheat Cropping System of Indian Sub-Himalayas

Resource conservation issues have drawn the attention of scientists to devise innovative tillage and crop establishment techniques for higher productivity in small holder farming systems in the tropics but relatively less attention has been given in rainfed sloping lands of the Indian sub-Himalayan (sub-temperate) regions. To investigate these issues, an experiment was conducted on resource conservation practices under rainfed conditions for 5 years (June 2007–May 2012) at Dehradun, Uttarakhand in the Indian Himalayan region. Four treatments, 1. 100:60:40 kg N:P₂O₅:K₂O + conventional tillage (CT) + chemical weeding + PANICUM vegetation strip (T₁); 2. FYM (5 t ha^?1) + minimum tillage (MT) + 1 weed mulch (30 DAS) @ 0.52 t ha^?1 + PALMAROSA vegetation strip (T₂); 3. FYM (5 t ha^?1) + vermi-compost (1.0 t ha^?1) + MT + 2 weed mulch (25 and 50 DAS) @ 1.47 t ha^?1 + PALMAROSA vegetation strip (T₃) and 4. FYM (5 t ha^?1) + vermi-compost (1.0 t ha^?1) + poultry manure (2.5 t ha^?1) + MT + 3 weed mulch (20, 40 and 60 DAS) @ 2.18 t ha^?1 + PALMAROSA vegetation strip (T₄). The results showed that resource conservation treatments (T₄, T₃ and T₂) had significant (P ≤ 0.05) multiple benefits as compared to traditional agriculture treatments (T₁). T₁ gives the highest yield of maize whereas T₄ gives highest yield of wheat. For the maize–wheat cropping system, mean wheat equivalent yield (WEY) was ~16 % higher in T₄ than T₁. Mean runoff was ~30 % lesser and mean soil loss was ~34 % lesser in T₄ as compared with T₁. Similarly, mean soil moisture conservation for rainfed wheat was ~31 % higher in T₄ than T₁. Mean carbon retention potential increased by ~53 % which subsequently increased mean soil quality index (SQI) by ~25 %. Mean energy productivity increased by ~70 % and mean energy intensiveness decreased by ~56 % in T₄ than T₁. Treatment T₁ (2,560 MJ^?1) emerged to be the most energy intensive system as compared to T₄ (1,113 MJ Rs.^?1). On an average, T₄ had 7 % higher net returns than T₁ and in terms of net returns per tonne of soil loss, T₄ was the best treatment (Rs. 4,907). Therefore, resource conservation system (PALMAROSA as a vegetation strip along with organic amendments, FYM, vermi-compost, poultry manure and weed mulch under minimum tillage) had significant positive impact on yield, resource conservation and energy saving and may be introduced as a substitute of conventional system in the Indian sub-Himalayas and under similar climatic and edaphic conditions.     

Efficient Nitrogen and Water Management for the Soybean–Wheat System of Madhya Pradesh,Central India,Assessed Using APSIM Model

A series of long-term simulations were carried out to investigate alternative management practices to increase grain yields of soybean and wheat by optimizing sowing dates, nitrogen (N) and water requirements, along with complimenting farmyard manure (FYM) as a N source in the soybean–wheat cropping system of Madhya Pradesh. The APSIM simulation study showed that the mean soybean yield ranged from 1.0 to 1.6 t ha^?1 for the different dates of sowing. The average wheat grain yield was 3.2–3.9 t ha^?1, whereas, the crop sown on 15 November gave the highest yield. In this region, there is a potential to increase soybean and wheat yields by 0.6 and 2.2 t ha^?1, respectively. Among the various irrigation practices simulated, five irrigations of 60 mm at 20 days interval was the best option for wheat. Application of 16 t FYM ha^?1 to soybean produced 50 % higher wheat yield than the same amount of FYM applied to wheat. The wheat yield obtained from inorganic application of N was at par with that obtained from the application of integrated and organic sources. However, the amount of N loss from the integrated use of fertilizer N was lower than that from the current recommended practice for the region. Application of FYM alone or in combination with inorganic fertilizer maintained higher soil organic carbon concentration as compared to the application of inorganic fertilizer alone. Thus, the model provided a mean of evaluating alternative crop N and water management options for effectively managing the soybean–wheat cropping system.     

Effects of Tillage and Residue Management Practices on Soil and Root Parameters in Soybean (<Emphasis Type="Italic">Glycine max</Emphasis>)–Wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis>) Cropping System

A field study was conducted during 2009–2011 to investigate the effect of tillage, crop establishment and residue management practices on soil and root parameters in soybean-wheat cropping system. The experiment was conducted with 4 main plot treatments of tillage and crop establishment techniques as conventional tillage-flat (CT-F), zero tillage-flat (ZT-F), conventional tillage-bed (CT-B) and zero tillage-bed (ZT-B); and 4 sub plot treatments of residue application as control, wheat residue (3 t ha^?1), soybean residue (3 t ha^?1) and soybean + wheat residue (3 t ha^?1 each). The infiltration rate was significantly higher with ZT-F (1.22 cm h^?1) and wheat + soybean residue application (1.16 cm h^?1). ZT-F and ZT-B recorded higher mean weight diameter and geometric mean diameter at 0–10 cm than that of CT-F and CT-B. The percentage of micro-aggregate was higher with CT-F and CT-B at all depths while the macro-aggregate was high with ZT-F and ZT-B up to 30 cm soil depth. The microbial biomass carbon in ZT-F and ZT-B was 216.3 and 214.6 µg g^?1 of soil, respectively which was significantly higher than that of CT-F and CT-B. The wheat + soybean residue application recorded 19.6 % higher MBC than the control. Among the tillage treatments, ZT-F performed well with regard to root length density as 2.38 and 1.11 cm cm^?3, root surface area as 0.67 and 0.36 cm² cm^?3, root volume density as 19.22 and 8.26 × 10^?3 cm³ cm^?3 and average root diameter as 1.06 and 0.81 mm by soybean and wheat, respectively. Similarly, wheat + soybean residue also performed better than the no residue treatment.     

High-Value Crops’ Imbedded Intensive Cropping Systems for Enhanced Productivity,Resource-Use-Efficiency,Energetics and Soil-Health in Indo-Gangetic Plains

An investigation was undertaken at New Delhi, India during 2011–2013 to assess the agro-economic potentiality of four promising high-value crops’ imbedded diversified intensive cropping systems (DICS) in order to diversify the cereal–cereal based rotations and owning maximum profitability in Indo-Gangetic Plain (IGPR) production systems. Cowpea–potato–mungbean (C–P–M_b) system proved as best viable option in realizing highest system-productivity in terms of mungbean-equivalent-yield (MEY), water-productivity and energy-relationships besides enhancing soil physico-chemical and microbiological properties; followed by Kharif onion–wheat–mungbean (O–W–M_b) system. C–P–M_b system also observed significantly highest net-returns, production and monetary-efficiencies. Application of 75 % recommended NPK (RDF) + vermicompost (VC) @ 5 t ha^?1 registered highest system-productivity (MEY) and production-efficiency followed by 100 % RDF, respectively. Application of 75 % RDF + VC @ 5 t ha^?1 also registered higher available N, P, soil–organic–carbon and DTPA-extractable micro-nutrients, besides enhanced microbial–biomass–carbon, respiratory and dehydrogenase activities. Overall, C–P–M_b and O–W–M_b systems supplied with 75 % RDF + VC @ 5 t ha^?1 may prove as viable alternative DICSs for enhanced system-productivity, profitability, water-productivity, energetics, and soil-health under irrigated IGPR.     

Domestic timber harvesting affects wood quantities in Tasmanian dry eucalypt forests

Domestic fuelwood harvesters illegally reduced coarse (≥10-cm diameter) downed woody debris stocks in Tasmanian mature dry eucalypt forests, 27–34 m tall, by 96.9 m³ ha^?1 or 22.7 t ha^?1. There was no effect of domestic harvesting on quantities of dead trees or live trees. Few dead trees were encountered in natural (unharvested) sites. Domestic harvesters preferentially removed debris <70 cm in diameter, leaving domestically harvested sites with 40% less volume and biomass of downed woody debris than natural sites. Assuming domestic harvesting, at the measured intensity, extends 25 m into forests either side of the state forest road system that passes through the studied forest type, dead wood stocks in that forest type and tenure throughout the state have been reduced by 688?000 m³ or 161?000 t. Domestic harvesting potentially damages biodiversity values, diminishes habitat available for species dependent on fallen logs and reduces forest carbon stocks. Domestic harvesters are advised to obtain licences to collect fuelwood from areas with an appropriate forest practices plan.     

Effect of Organic Sources of Nutrients on Tuber Bulking Rate,Grades and Specific Gravity of Potato Tubers

A field experiment was conducted during 2008–2009 and 2009–2010 to investigate the effect of organic sources of nutrients on tuber bulking rate, grades and specific gravity of potato tubers. The experiment consisted 24 treatment combinations with 8 treatment in popcorn [control, recommended dose of fertilizers (N₁₂₀P₂₅K₃₅ kg ha^?1), farmyard manure equivalent to 120 kg N ha^?1, leaf compost equivalent to 120 kg N ha^?1, vermicompost equivalent to 120 kg N ha^?1, farmyard manure equivalent to 90 kg N ha^?1, leaf compost equivalent to 90 kg N ha^?1 vermicompost equivalent to 90 kg N ha^?1 in succeeding crop of potato, three treatments [control, farmyard manure equivalent to 60 kg N ha^?1 and farmyard manure equivalent to 90 kg N ha^?1] were superimposed on the different treatments of pop corn. It was found that the application of farmyard manure equivalent to120 kg N ha^?1 to pop corn and farmyard manure equivalent in 90 kg N ha^?1 in potato gave the highest values of tuber bulking rate, specific gravity, number of large–sized (A–grade) and medium–sized tubers (B–grade) and total tuber yield followed by vermicompost equivalent to to 120 kg N ha^?1. Farmyard manure equivalent to 90 kg N ha^?1 to potato also recorded the higher bulking rate, tuber yield, specific gravity and a number of large sized tubers (A– grade and B–grade) as compared to the farmyard manure equivalent to 60 kg N ha^?1. The available N, P, and K in soil also improved with the application of organic manures.     

Herbicides for use in management of certified Pinus radiata plantations in New Zealand

Post-planting vegetation control in commercial Pinus radiata D.Don forests within New Zealand almost exclusively uses a mixture of the two triazine herbicides, terbuthylazine and hexazinone. However, neither of these herbicides is endorsed for use on land certified by the Forest Stewardship Council (FSC), based on criteria relating to their persistence or toxicity in the environment. This is a problem for the forest industry as these herbicides are inexpensive, are not phytotoxic to P. radiata, and their residual action enables continued control of competing vegetation for up to a year following application. Using measurements obtained from three short-term field trials where herbicides were applied as pre- and post-emergent, post-planting treatments to a wide range of competitive vegetation species, the efficacy of alternative mixes of herbicides was compared to the triazine mix (the current industry standard). As the restrictions on the use of terbuthylazine by FSC may be lifted, this herbicide was also trialled in mixes with herbicides other than hexazinone. Tree growth was quantified one year after herbicide application using a biomass index. Results from all three trials showed that the triazine mix provided the greatest level of vegetation control, with the trees in this treatment attaining the highest biomass index. Where herbicide mixes were applied as pre-emergent treatments, the best alternative herbicide, as assessed by tree growth at one year, was indaziflam applied at 300 g active ingredient (a.i.) ha^–1. Compared to the triazine mix, the biomass index for this treatment was reduced by <1%. Where herbicides were applied as post-emergent treatments, the best alternatives to the triazine mix were very similar across trials and included treatments where terbuthylazine (at 7000 g a.i. ha^–1) had been applied in combination with one of either mesotrione (at 150 g a.i. ha^–1; 300 g a.i. ha^–1), triclopyr (at 113 g a.i. ha^–1), or clopyralid (at 1500 g a.i. ha^–1) or where a mixture of clopyralid, triclopyr and haloxyfop (1125 g a.i. ha^–1, 113 g a.i. ha^–1 and 250 g a.i. ha^–1) was used. Reductions in biomass index at one year in these five treatments, relative to the triazine mix, ranged between 5% and 35%, with smallest reductions being recorded for terbuthylazine used in combination with either clopyralid or mesotrione.     

Wood properties of Eucalyptus globulus at three sites in Western Australia: effects of fertiliser and plantation stocking

Wood properties of 10-year-old trees in Eucalyptus globulus plantations at three sites in Western Australia were examined. Silvicultural treatments applied at age two years were stocking (unthinned, 1250 stems ha^–1; thinned to 600 stems ha^–1 or 300 stems ha^–1) and nitrogen fertiliser application (0 or 250 kg ha^–1 elemental nitrogen) in factorial combination. The three sites differed markedly in their annual rainfall (620–1100 mm), open-pan evaporation and soil water-holding capacity. Wood cores were collected at breast height from a total of 263 trees (~15 trees for each site-by-treatment combination), and radial samples prepared for analysis by SilviScan to produce radial profiles of air-dry density and microfibril angle (MFA) and modulus of elasticity (MOE), and by radial near infrared (NIR) surface scanning to produce radial profiles of NIR-predicted Kraft pulp yield (KPY) and cellulose content (CC). Sampling interval was 0.025 mm for density and 5 mm for the other properties. For wood property mean values (i.e. wood property averages of each pith-to-cambium sample), sites differed significantly only in air-dry density. The Boyup Brook site, which had low annual rainfall, the lowest climate wetness index and soil water-storage capacity and the slowest diameter growth, had the highest mean wood density (648 kg m^–3), while Scott River, with the highest rainfall, had mean density that was 10% lower. The Wellstead site (low rainfall but highest soil water-storage capacity) was intermediate for density. The only other significant differences for mean wood properties were caused by fertiliser addition, which reduced NIR-predicted KPY from 54.6% (without fertiliser) to 54.1% and predicted CC from 43.7% to 43.1%. Clear radial trends were evident for all wood properties. Density, MOE, KPY and CC all increased from pith to the cambium, while MFA declined. From the innermost (pith) 10% to the outermost (cambial) 10% of the radius, density increased on average by 21%, MOE by 103%, KPY by 9% and cellulose by 11%, while MFA declined by 47%. NIR calibrations developed using the SilviScan and NIR spectral data explained 71% of variance in MOE for an independent set of radial wood samples of E. globulus from Victoria, but less than 50% of variance for density and MFA. Implications for paper pulp and veneer manufacture are briefly considered.     

Managing wood production from small grower acacia hybrid plantations on eroded soils in central Vietnam

An experiment in a second rotation acacia hybrid (Acacia mangium × A. auriculiformis) clonal plantation in central Vietnam examined factors determining total wood production and its apportionment to sawlog and pulpwood. Growth and stand characteristics were compared with those in nearby plantations owned by small growers. The experimental site was on sloping land damaged and eroded by war and previous land use. The soil was shallow, with 20–30% laterised stones by volume and had lost part of the A horizon. Mean annual increment (MAI, in standing merchantable volume over bark) of the first rotation at age 8.8 years was 17 m³ ha^?1 y^?1. In the second rotation at age 7.6 years it was 20 m³ ha^?1 y^?1. Application of P fertiliser at three rates ranging from 14 to 86 kg ha^?1 increased stem diameter over the second rotation although stand volume response to P was not significant by rotation end. Potassium (14 kg ha^?1) gave no growth response. Growth rate was similar under weed control by herbicide and manual means. MAI increased progressively from 16.5 m³ ha^?1 y^?1 at the hilltop to 25.0 m³ ha^?1 y^?1 at the lowest part of the experiment; slope position influenced growth more than management practices. Key soil properties, pH, N, Bray-1 P and organic C were maintained from the first to the second rotation. With simple management practices including conservation of site organic matter and early stand management, appropriate for local small growers, the second rotation yielded 46% of harvested volume as sawlogs and the balance as pulpwood. Although small growers achieved similar growth rates, their current management regime does not yield sawlogs. They can influence the log categories produced and stand value through changes to stocking rate, stand management and rotation age.     

Fertilization and Crop Residue Addition Impacts on Yield Sustainability Under a Rainfed Maize–Wheat System in the Himalayas

A 9-year old experiment was conducted at Almora, India to study the effects of mineral sources of nutrients in different combinations with or without crop residue or farmyard manure (FYM) addition on crop productivity under a rainfed maize–wheat system. Plots under 100 % nitrogen–phosphorus–potassium (NPK) + FYM had maximum mean maize (5.00 Mg ha^?1) and wheat (2.61 Mg ha^?1) yields that were generally significantly higher than yields observed under other treatments. Total soil organic carbon (C) increased in all treatments except with mineral fertilization and control plots. While NPK treated plots had significantly higher benefit:cost ratio than NPK + FYM plots, organic C content in the NPK treated plots decreased over the initial soil and FYM treated plots had better soil physical and chemical properties than NPK only. Thus, the study showed that although the combined 100 % NPK and FYM application had higher productivity of the maize–wheat system, the same is as remunerative as 50 % NPK + FYM, if the cost of FYM was considered. However, depending upon the resource availability, farmers can also apply Kudzu, maize stalk and wheat straw annually along with adjusted dose of NPK to a crop and full dose of NPK to the other crop as the alternate options.     

Bio-efficacy of Herbicides on Performance of Mustard, <Emphasis Type="Italic">Brassica juncea</Emphasis> (L.) and Population Dynamics of Agriculturally Important Bacteria

The bio-efficacy of different herbicide treatments on the performance of mustard crop and its effect on population dynamics of beneficial soil microorganisms like Azotobacter (aerobic and free-living nitrogen fixing bacteria), Bacillus and Pseudomonas (phosphate solubilisation and biocontrol agents) were studied. Higher doses of pendimethalin (@1.0 kg ha^?1) and isoproturon (@1.0 kg ha^?1) had toxic effect on the germination (13.33 and 17.33 m^?2) and emergence of mustard crop and resulted in significantly lower plant population. These treatments resulted in reduction of plant population to the tune of 47.92 and 31.48 % at 30 days after sowing (DAS) and 47.06 and 27.96 % at harvest. Weed free treatment recorded significantly higher seed yield (2781 kg ha^?1) which was about 99 % more than the weedy check. The increase in seed yield with different herbicides was to the tune of 27–73 % over weedy check, except pendimethalin @1.0 kg ha^?1 as pre-emergence (PE). The weedy check plot showed highest population of Azotobacter, Bacillus, and Pseudomonas throughout the observation period. However, among different herbicide treatments, the highest population of Azotobacter and Bacillus was observed with pendimethalin 0.5 kg ha^?1 as PE and that of Pseudomonas with isoproturon 1.0 kg ha^?1 30 DAS at harvest stage.     

Provenance variation,genetic parameters and potential gains from selection for biomass and cineole production in three-year-old Eucalyptus loxophleba subsp. gratiae progeny trials

ABSTRACT

Ninety families from six provenances of Eucalyptus loxophleba subsp. gratiae were established near Brookton, Western Australia, and Condobolin, New South Wales, and 89 of these same families were established at Monarto, South Australia. All three trials were assessed at age three years for biomass productivity and the trial at Brookton was assessed for leaf cineole concentration. Provenance performance across the sites was most similar between Monarto and Condobolin, while the ranking of provenances was more divergent between those sites and Brookton. Presence or absence of unstable families may change provenance ranking. Additive variance was not significant for the Condobolin trial. Heritability of green biomass at age three years was ?² = 0.19 ± 0.06 and ?² = 0.16 ± 0.05 at Monarto and Brookton, respectively. The heritability of leaf cineole concentration at Brookton was ?² = 0.50 ± 0.08 and whole-tree cineole yield, ?² = 0.11 ± 0.04. The cross-site genetic correlation between Brookton and Monarto was r_g = 0.55 ± 0.20, suggesting the presence of some genotype × environment interaction. Removing the six most unstable families resulted in a cross-site genetic correlation of r_g = 0.97 ± 0.25. Estimated mean gains from selection scenarios treating Brookton and Monarto as representing two separate environments or as a single environment differed by about 5.0%. The exclusion of six unstable families reduced that difference to 1.4%. Selection on biomass alone may result in a slight increase in total cineole yield per tree but, in this experiment, it resulted in a reduction in mean leaf cineole concentration. Leaf cineole concentration used in conjunction with biomass may be a useful selection criterion in the absence of data for total mass of cineole produced per tree.     

Eucalyptus growth in relation to combined nitrogen and phosphorus fertiliser and soil chemistry in Tasmania

Two experiments were established to determine the early nutrient requirements for plantations of Eucalyptus globulus (Nabowla site) and E. nitens (Westfield site) in Tasmania, Australia. Nitrogen (N) and phosphorus (P) were broadcast together, 2 and 26 months after planting, at cumulative rates of up to 1200 kg N ha^?1 600 kg P ha^?1. Soil chemistry was characterised at each site in three profiles, and in all plots at the Westfield site. Nabowla has a relatively infertile, poorly structured soil, low in N and P, and receives about 800 mm of rainfall per annum. Growth was very poor without fertiliser, but trees responded rapidly and strongly to added NP. Stem volume increased directly with the rate of applied fertiliser, with no evidence that the response had peaked at the highest rate. Even at the highest rate of NP fertiliser, however, productivity was relatively low (mean annual increment about 15 m ha^?1 y^?1). Establishment of plantations on such sites is unlikely to be economically viable, with or without fertiliser, but fertile ex-pasture sites that are otherwise similar should be considered. Westfield has a relatively fertile, well-structured soil, and receives 1400–1500 mm of rainfall per annum. Response to NP fertiliser was delayed at this site, with first responses measured 33 months after planting. The response in stem volume was sigmoidal in relation to fertiliser rate, with a plateau at an application rate of 400 kg N ha^?1 and 200 kg P ha^?1. This rate of fertiliser is expected to increase mean annual increment from 20 (without fertiliser) to 25 m ha^?1 y^?1. Splitting applications of fertiliser at the highest rate did not alter the growth response.

Although high rates of N and P fertiliser may be required to maximise growth of eucalypt plantations in Tasmania on ex-forest sites, rates required during the first few years might be lower than those reported here if the timing and placement of fertiliser is optimised. Soil chemical analyses were indicative of N and P requirements, and about a third of the variation in growth across the Westfield site was accounted for by natural variability in initial concentrations of total P and exchangeable K in surface soil.     

Quantitative and qualitative assessment of timber harvesting residues: a case study of a balsa plantation in Papua New Guinea

The quantity and quality of the harvesting residues in a balsa plantation in East New Britain Province of Papua New Guinea are reported in this paper. The plantation was harvested manually with a chainsaw and manpower to extract the industrial wood at age 6 years. A modified standard harvesting residue assessment method using plots on line transects was applied. The total weight of the harvest residues remaining on the site after wood extraction was 211.7 t_GREEN ha^?1 (tonnes (green) per hectare). The major component was un-merchantable stem wood (121.3 t_GREEN ha^?1; 57.3%), followed by bark (59.3 t_GREEN ha^?1; 28.0%). This level of harvest residue was relatively greater than that reported in other studies, reflecting the combination of the log specification applied and the nature of the stem defects in balsa trees. The level of residues indicates the possibility of additional woody material recovery for bioenergy after consideration of sustainability issues.

The average moisture content of the wood components of the residues was determined over two days. The average moisture content on the first day after harvesting was 50%, falling in the following day to about 48%. The abundance of five elements in the harvest residues was estimated using data from a single sample tree; of the elements assessed potassium was the most abundant while calcium was the least.     

Efficiency of nutrient use for biomass production of a Eucalyptus clone as a function of planting density in short-rotation cropping

ABSTRACT

The objective of this study was to assess the effects of planting density on nutrient use efficiency (NUE) in the production of biomass of a hybrid of Eucalyptus urophylla × Eucalyptus grandis. Twelve planting densities were evaluated at 36 months of age, ranging from 498 to 2564 plants ha^?1. Three trees were harvested in each treatment to determine biomass production and allocation (per plant and per area), concentration (g kg^?1), amount (kg ha^?1), and NUE of N, P, K, Ca, Mg and S in the biomass of leaves, branches, bark and wood. In summary, the increase in planting density resulted in: higher biomass production per area; a reduction in biomass production per plant; a reduction in homogeneity; an increase in the concentration of N, P and K in leaves, of N, Ca, Mg and S in bark, and of N, P and K in wood; a higher amount of nutrients exported by harvesting; and a higher NUE for wood production. The increase in NUE indicates a possible nutritional deficit in trees at higher stocking rates at the age of three years. The higher the planting density, the sooner the site will require re-fertilisation.     

Expenditure on forestry and forest products research in Australia 2007–2008

Total expenditure on forestry research and forest products research in 2007–2008 in Australia was $87.8 million. This comprised $61.0 million on forestry research and $26.8 million on forest products research and was estimated using the same methods as in the several previous assessments (Quick and Booth 1987; Lambert and Turner 1992; Turner and Lambert 1997,2005). When some peripheral expenditure such as support, administration and surveys were included, the total expenditure increased to about $105.8 million. The total expenditure represents an annual average increase of about 3% since 1982 but a slow decline (0.45% per annum) in adjusted terms (1982 dollars). About 50 organisations reported undertaking forestry and or forest products research, while other organisations provided funding for research. The expenditure was attributed to four broad sectors undertaking research—Commonwealth, state, university and private—and also to broad research areas (native forests, exotic species plantations, native species plantations and environment). Research on native forests and exotic species plantations generally declined, whereas that on surveys in native forests and native species in plantations increased from 2001–2002 to 2007–2008. Similarly, research capacity declined in traditionally strong research areas such as pests and diseases and fire behaviour, and increased in energy areas such as carbon and forest bio-energy. About 600 full-time-effective researchers and technicians were involved in research in 2007–2008, plus support and management staff. The staffing numbers of individual organisations ranged from single individuals to more than fifty.

In 2007–2008, about 52% of the research funds were provided directly or indirectly by the Commonwealth Government, 28% by state governments and 20% by private companies. Total expenditure on forestry and forest products research ($87.8 million) averaged $5.78 ha^?1 of managed forest. The forestry research expenditure according to forest type comprised $14.80 ha^?1 on exotic species plantations, $36.90 ha^?1 on native species plantations and Total expenditure on forestry research and forest products research in 2007–2008 in Australia was $87.8 million. This comprised $61.0 million on forestry research and $26.8 million on forest products research and was estimated using the same methods as in the several previous assessments (Quick and Booth 1987; Lambert and Turner 1992; Turner and Lambert 1997,2005). When some peripheral expenditure such as support, administration and surveys were included, the total expenditure increased to about $105.8 million. The total expenditure represents an annual average increase of about 3% since 1982 but a slow decline (0.45% per annum) in adjusted terms (1982 dollars). About 50 organisations reported undertaking forestry and or forest products research, while other organisations provided funding for research. The expenditure was attributed to four broad sectors undertaking research—Commonwealth, state, university and private—and also to broad research areas (native forests, exotic species plantations, native species plantations and environment). Research on native forests and exotic species plantations generally declined, whereas that on surveys in native forests and native species in plantations increased from 2001–2002 to 2007–2008. Similarly, research capacity declined in traditionally strong research areas such as pests and diseases and fire behaviour, and increased in energy areas such as carbon and forest bio-energy. About 600 full-time-effective researchers and technicians were involved in research in 2007–2008, plus support and management staff. The staffing numbers of individual organisations ranged from single individuals to more than fifty.

In 2007–2008, about 52% of the research funds were provided directly or indirectly by the Commonwealth Government, 28% by state governments and 20% by private companies. Total expenditure on forestry and forest products research ($87.8 million) averaged $5.78 ha^?1 of managed forest. The forestry research expenditure according to forest type comprised $14.80 ha^?1 on exotic species plantations, $36.90 ha^?1 on native species plantations and $0.99 ha^?1 on native forests (including ecological and environmental research, and hydrological studies and fauna-flora research). Additionally, there was expenditure of about $0.45 ha^?1 on land-based surveys (mainly biodiversity), primarily in native forests. Total expenditure on forestry and forest products research equated to an average of $3.90 m^?3 of harvested timber. This comprised $1.02 m ³ on timber removals from exotic species plantations, $7.38 m^?3 from native species plantations and $1.90 m^?3 from native forests.     

The potential of Sentinel-2 data for estimating biophysical variables in a boreal forest: a simulation study

In this study we use ground reference data from 962 forest plots to demonstrate the potential of Sentinel-2 (S2) bands in estimating canopy biophysical properties in boreal forests in Finland. We simulated canopy bidirectional reflectance factors (BRFs) using the PARAS model, which applies photon recollision probability. Results showed that the highest correlation between simulated S2 BRFs and fraction of absorbed photosynthetically active radiation (fPAR) was for the band combination band 7/band 9 (wavelengths 773–793 nm and 935–955 nm, respectively) (the coefficient of determination (R²) was 0.93). For effective leaf area index (LAI_e) the best band combination was band 8/band 4 (wavelengths 785–900 nm and 650–680 nm, respectively) (R² = 0.93). Based on this study, the above-ground biomass (AGB) and S2 band combinations did not show strong relationships (R² = 0.24). The new inverted red-edge chlorophyll index (IRECI) and Sentinel-2 red-edge position – index (S2REP) showed moderate relationships with fPAR (R² = 0.61 and R² = 0.45, respectively) and LAI_e (R² = 0.56 and R² = 0.30, respectively). This study demonstrated the potential of the S2 data to estimate canopy biophysical properties.     

Effect of Nitrogen Fertilizer on Grain Yield and Nitrogen Use Efficiency in Corn (Zea mays L.) Hybrids Under Irrigated Conditions

In order to study the effect of nitrogen rates on grain yield and nitrogen use efficiency of corn (Zea mays L.) hybrids, a field experiment was conducted in south-western Iran during 2011–2012. The experiment was split-plot with RCBD arrangement in three replications. Main plots consisted of four nitrogen rates (0, 90, 180 and 260 kg N ha^?1) and four corn hybrids (Sc.704, Sc.640, Mobeen and DKC6589) were placed in sub-plots. Results indicated that the effect of nitrogen, hybrids and their interaction on corn grain yield was significant. Increase in nitrogen rates from 0 to 90, 180 and 260 kg N ha^?1 increased the mean grain yield studied hybrids by 42.6, 55 and 58 %, respectively. DKC6589 hybrid and Mobeen had the highest and lowest grain yield among studied hybrids. Higher grain yield in DKC6589 was due to higher number of grains per ear and 100-grain weight. The results of step-wise regression coefficients also indicated that number of grains had the maximum contribution in grain yield. As compared to grain yield of Mobeen and Sc.640 hybrids at the levels of 180 and 260 kg N ha^?1, DKC6589 hybrid yield was more in the treatment of no nitrogen. The maximum grain yield was obtained in DKC6589 hybrid and 180 kg N ha^?1. Increase of nitrogen up to 260 kg N ha^?1 led to the significant increase in grain yield of 640 hybrid, but in other hybrids, increase of nitrogen up to more than 180 kg N ha^?1, slightly decreased the grain yield. There was genetic variation for nitrogen use efficiency. It is possible to select hybrids with higher nitrogen use efficiency to reduce the fertilization. Positive and significant relation between grain yield and nitrogen use efficiency was marked. DKC6589 hybrids as compared to other hybrids had more nitrogen use efficiency and agronomic nitrogen use efficiency in lower amount of fertilizer. Generally, it seemed that DKC6589 hybrid had all ideal traits of implantation in the region as the potential of its grain yield was very high.     

Nutrient management of contrasting Acacia mangium genotypes and weed management strategies in South Sumatra,Indonesia

ABSTRACT

Tropical plantations are an important source of forest products both to meet the growing demand for wood, and to facilitate the transition from native forests to more sustainably produced forest resources. Management of these plantations for optimal productivity and resource-use efficiency is vitally important, and nutrient management is a critical component of sustainable plantation production. In this study, we explored the response of Acacia mangium plantations in South Sumatra, Indonesia, to fertiliser and their requirement for fertiliser, focusing on phosphorus (P) at establishment. Almost all plantations across a series of 11 sites were highly responsive to P fertiliser, with nine of the 11 sites having more than double the productivity in P-fertilised treatments at age 1 year compared with control treatments. However, the quantity of P required for 90% of maximum growth was generally low by age 2 or 3 years, and 10 kg P ha^–1 at establishment was sufficient to ensure that at least 90% of maximum growth was captured across all the experimental sites. At a 12^th site, we explored the interactions between genotype and weed control, and found that both effects were additive in the response of the plantations to P, and thus there was no substitutability between management types: weed control, genotype and P needed to be managed in combination to achieve maximum productivity.