Abstract
To produce large volumes of biomass for implementing its green energy policy, the Government of Indonesia has issued a short rotation energy plantation program for a number of tree species including Calliandra calothyrsus (Meissn.). Optimum density and prompt harvesting are needed to maximise productivity, but information regarding both factors is insufficient. This study aimed to investigate the optimum growth spacing and ideal felling age to produce the largest volumes of biomass both economically and sustainably. Experiments were arranged on one hectare of land, which was divided into four plots with different plant spacing treatments (1 × 1.5 m; 1.5 × 1.5 m; 2 × 1.5 m; and 2 × 2 m). Growth and yield observations were carried out on plants aged 12, 18, and 24 months in each plot, with 30 sample trees left for growth observations and ten sample trees cut at each of the three ages after planting. This resulted in a total of 240 samples from the 2,710 trees planted. Trees were felled at 50 cm from the soil surface, and the resulting stools were left to regrow. A year after felling, resulting coppices, were observed and cut. Growth, productivity and calorific value were studied for both ‘primary’ and ‘coppiced’ wood. Study results demonstrate that competition between plants strongly determines the growth and productivity of ‘primary’ wood. The plot with the densest plant spacing had the lowest nutrient content for almost all soil nutrients. Higher plant density showed higher competition index values, and resulted in fewer and smaller diameter stems emerging from stools, and lower biomass productivity. Competition index values, which increased with plant age, can be used as an indicator for determining harvest timing. Productivity increased by up to 15% following development as a coppice plantation. Optimum wood productivity and greatest economy came from parent stands with plant spacing of 2 × 2 m, harvested at 18 months old and coppiced. This treatment yielded an average biomass/tree of primary wood 7.2 kg and coppice wood 8.22 kg, respectively, with lignin content of approximately 22%, and calorific value of around 18,807 kJ. These values match biomass energy requirements for feedstock for electricity generation. Harvesting at 24 months showed no significant increases in productivity, lignin content, or calorific value.
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Claims 16
Claim · model-written summary
Competition influenced primary wood growth and productivity.
- Taxon
- Calliandra
Calliandrat0 - Outcome
- growth and productivity of ‘primary’ woode0
- Qualifier
- competition between plantse0
Not reportedSettingDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“competition between plants strongly determines the growth and productivity of ‘primary’ wood”
t0“Calliandra short-rotation-coppice plantation”
Claim · model-written summary
The densest spacing had the lowest content for almost all soil nutrients.
- Taxon
- CalliandraCalliandrat0
- Treatment
- densest plant spacinge0
- Outcome
- nutrient content for almost all soil nutrientse0
- Direction
- loweste0
- Setting
- plote0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The plot with the densest plant spacing had the lowest nutrient content for almost all soil nutrients”
t0“Calliandra short-rotation-coppice plantation”
Claim · model-written summary
Higher density increased competition index.
- Taxon
- CalliandraCalliandrat0
- Treatment
- Higher plant densitye0
- Outcome
- competition index valuese0
- Direction
- highere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Higher plant density showed higher competition index values”
t0“Calliandra short-rotation-coppice plantation”
Claim · model-written summary
Higher density produced fewer stems from stools.
- Taxon
- CalliandraCalliandrat0
- Treatment
- Higher plant densitye0
- Outcome
- stems emerging from stoolse0
- Direction
- fewere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Higher plant density showed higher competition index values, and resulted in fewer and smaller diameter stems emerging from stools, and lower biomass productivity”
t0“Calliandra short-rotation-coppice plantation”
Claim · model-written summary
Higher density produced smaller stem diameters.
- Taxon
- CalliandraCalliandrat0
- Treatment
- Higher plant densitye0
- Outcome
- diameter stems emerging from stoolse0
- Direction
- smallere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Higher plant density showed higher competition index values, and resulted in fewer and smaller diameter stems emerging from stools, and lower biomass productivity”
t0“Calliandra short-rotation-coppice plantation”
Claim · model-written summary
Higher density lowered biomass productivity.
- Taxon
- CalliandraCalliandrat0
- Treatment
- Higher plant densitye0
- Outcome
- biomass productivitye0
- Direction
- lowere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Higher plant density showed higher competition index values, and resulted in fewer and smaller diameter stems emerging from stools, and lower biomass productivity”
t0“Calliandra short-rotation-coppice plantation”
Claim · model-written summary
Competition index rose with plant age.
- Taxon
- CalliandraCalliandrat0
- Organ / stage
- plant agee0
- Outcome
- Competition index valuese0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Competition index values, which increased with plant age”
t0“Calliandra short-rotation-coppice plantation”
Claim · model-written summary
Coppice development increased productivity by up to 15%.
- Taxon
- CalliandraCalliandrat0
- Treatment
- development as a coppice plantatione0
- Outcome
- Productivitye0
- Direction
- increasede0
- Value
- up to 15%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Productivity increased by up to 15% following development as a coppice plantation”
t0“Calliandra short-rotation-coppice plantation”
Claim · model-written summary
Spacing of 2 × 2 m and harvest at 18 months with coppicing gave optimum wood productivity and economy.
- Taxon
- CalliandraCalliandrat0
- Treatment
- plant spacing of 2 × 2 m, harvested at 18 months old and coppicede0
- Outcome
- wood productivity and greatest economye0
- Direction
- Optimume0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Optimum wood productivity and greatest economy came from parent stands with plant spacing of 2 × 2 m, harvested at 18 months old and coppiced”
t0“Calliandra short-rotation-coppice plantation”
Claim · model-written summary
The optimum treatment yielded 7.2 kg primary wood biomass per tree.
- Taxon
- CalliandraCalliandrat0
- Treatment
- This treatmente0
- Outcome
- biomass/tree of primary woode0
- Value
- 7.2 kge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This treatment yielded an average biomass/tree of primary wood 7.2 kg and coppice wood 8.22 kg, respectively”
t0“Calliandra short-rotation-coppice plantation”
Claim · model-written summary
The optimum treatment yielded 8.22 kg coppice wood biomass per tree.
- Taxon
- CalliandraCalliandrat0
- Treatment
- This treatmente0
- Outcome
- coppice woode0
- Value
- 8.22 kge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This treatment yielded an average biomass/tree of primary wood 7.2 kg and coppice wood 8.22 kg, respectively”
t0“Calliandra short-rotation-coppice plantation”
Claim · model-written summary
The treatment produced approximately 22% lignin content.
- Taxon
- CalliandraCalliandrat0
- Outcome
- lignin contente0
- Value
- approximately 22%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“with lignin content of approximately 22%, and calorific value of around 18,807 kJ”
t0“Calliandra short-rotation-coppice plantation”
Claim · model-written summary
The treatment produced calorific value around 18,807 kJ.
- Taxon
- CalliandraCalliandrat0
- Outcome
- calorific valuee0
- Value
- around 18,807 kJe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“with lignin content of approximately 22%, and calorific value of around 18,807 kJ”
t0“Calliandra short-rotation-coppice plantation”
Claim · model-written summary
Harvest at 24 months did not significantly increase productivity.
- Taxon
- CalliandraCalliandrat0
- Treatment
- Harvesting at 24 monthse0
- Outcome
- productivitye0
- Direction
- no significant increasese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Harvesting at 24 months showed no significant increases in productivity, lignin content, or calorific value”
t0“Calliandra short-rotation-coppice plantation”
Claim · model-written summary
Harvest at 24 months did not significantly increase lignin content.
- Taxon
- CalliandraCalliandrat0
- Treatment
- Harvesting at 24 monthse0
- Outcome
- lignin contente0
- Direction
- no significant increasese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Harvesting at 24 months showed no significant increases in productivity, lignin content, or calorific value”
t0“Calliandra short-rotation-coppice plantation”
Claim · model-written summary
Harvest at 24 months did not significantly increase calorific value.
- Taxon
- CalliandraCalliandrat0
- Treatment
- Harvesting at 24 monthse0
- Outcome
- calorific valuee0
- Direction
- no significant increasese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Harvesting at 24 months showed no significant increases in productivity, lignin content, or calorific value”
t0“Calliandra short-rotation-coppice plantation”