Abstract
This study examines the ecological characteristics and processes that lead to thenformation of stands dominated by A. thurifera (Dipterocarpaceae) in Papua NewnGuinea. The studies examined seedling regeneration through to standndevelopment and explored how this ecological information might be used tondevelop silvicultural methods for managing these forests.n The distribution of A. thurifera across PNG was assessed and the species wasnfound to occur in two situations. In some sites it occupied more than 40 percentnof the basal area or 50 percent canopy cover and formed what shall be referred tonin this thesis as qmonodominantq stands. These stands were common in forestsnalong the Morobe Coast. The second situation when there were found where A.nthurifera was less dominant in the stand. The forests at Kuriva and Sagaraintypified this.n The impact of logging on forest containing A. thurifera was assessed at fivenpaired logged and unlogged sites. Logging commonly removes 25 - 40 percentnof the stand basal area, depending on the original species composition, size classndistribution and logging intensity. Logging therefore affects the recruitment andngrowth of A. thurifera. In certain instances, where more than 70 percent of thenbasal area is removed, few residuals are retained and the capacity to replenishnlarge disturbed areas is minimized. However, with low intensity logging, speciesncomposition of the original forest is retained. In some sites, the effect of loggingnwas found to increase A. thurifera populations over time as well as in increasedngrowth of the residual trees.n The flowering and fruiting patterns of A. thurifera also affect the waynregeneration occurs at disturbed sites. A total of 158 trees of varying size classesnwere monitored over four years at Oomsis forest. Data analysis showed that thentiming of flowering varies but most tend to flower at the late dry period and thenearly wet season, which is between August and November. It also showed that A.nthurifera has a more regular flowering and fruiting pattern than many otherndipterocarps. Mast fruiting occurs every three to five years but otherwise there isnsporadic annual flowering and fruiting. The community flowering andnsubsequent fruiting lasts a maximum of nine months from the first appearance ofnflowering to the final seed rain.n Seed rain was assessed using 217 traps of 1.8 m x 2 m laid at the base of parentntrees and in a grid pattern to capture the seeds. The data showed that thenquantity and quality of seed production depended on parent tree size and thenflowering intensity. The most productive size class was stems larger than 50 butnl 90 cm dbh. It was further found that majority of the seeds were dispersednwithin ten metres radius of the parent tree crown.n The viability of A. thurifera seeds was further assessed by examining the sizenclass of parent trees and at different stages of the seed rain period. The resultsnshowed that viability increased according to seed maturity and was highestnimmediately upon seed fall. Further tests to determine seed viability uponnstorage at room temperature revealed that those stored for 21 days all lostnviability but those stored for 14 days had 68 percent viability.n Predation was assessed at different stages of the seed rain. The results showednthat predation commences very early during the development phase of the seedsnand continued until the end of the fruiting season. It was found that pre-dispersalnpredation was high affecting 50-65 percent of the total seeds produced in anseason. Major predators were insects, birds and pigs. It was also found that thenpopulation of the predators increased during the fruiting period, especially ofnbirds (parrots) and pigs. The overall predation was found to be 85 percent of thenseeds produced.n The dynamics of A. thurifera seedlings on the forest floor under closed canopiesnwas examined by establishing four 2 m x 2 m plots under each of 23 parent treesnover three years. This showed that the number of seedlings regeneratingndepended on the intensity of fruiting and stand density, averaging at 0.42nseedlings m-2 during the study period. The continued presence of establishednseedlings on the forest floor depended on factors such as the ability of the speciesnto persist and the forest type in which it occurs. At Oomsis, being a secondarynforest, 64 percent of the original seedlings persisted over three years, and 79npercent of those recruited in December 2001 survived after seven months. Whilenmortality was found to be high immediately after germination this stabilised overntime. Mortality was also high in the lower height classes and decreased withnincreasing height classes. Seedling height growth averaged at 7 cm year-1 and thenhighest growth rates were recorded in younger seedlings and among thosengrowing under higher light levels.n The optimum requirements of sunlight for the growth of A. thurifera seedlingsnwere further examined in a study using five levels of light treatment over 56nweeks. The treatments were, 10, 30, 50, 75 and 100 percent Relative lightnIntensity (RLI). Results showed that the highest growth rates were attainednunder the 30 percent RLI. While survival was 100 percent in all treatments, thencontrol had 93 percent survival over the same period. Growth in the first 16-20nweeks were unaffected by the quantity of light, suggesting that this species canngerminate and get established under poor light conditions. However, lightnbecomes essential for the advancement in growth. It also showed that open lightnconditions are unsuitable for the growth of this species.n The effects of silvicultural treatment on the growth, recruitment and mortalitynwere examined at Oomsis in a regrowth forest stand that had developed 20 yearsnafter logging. Four treatments were used; high thinning, medium thinning, lownthinning and an unthinned control. Treatment prescriptions were BA limits. Thenresults of this study showed that the highest growth rates for A. thurifera werenattained under the high thinning treatments. Similar responses were found fornother species present in these stands. The abnormally dry weather conditionsnextending over nine months during the study period and an anomalousnexperimental design may have affected some of the results. There was nonsignificant effect of the treatment on recruitment or mortality over the previousnfive-year study period. The results also showed that the trees in the 20 - 40 cmnsize class responded greatly to the treatments. This are the potential crop treesnfor the next harvest.n This information was used to explore the silvicultural prescriptions that might benused to manage A. thurifera forests in PNG.nn
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Claims 20
Claim · model-written summary
A. thurifera formed dominant stands on the Morobe Coast.
- Taxon
- anisoptera thuriferaAnisoptera thuriferat0
- Outcome
- These stands were common in forestsnalong the Morobe Coast.e0
Verbatim
e0“These stands were common in forestsnalong the Morobe Coast.”
t0“anisoptera thurifera”
Claim · model-written summary
Logging removed 25 to 40 percent of stand basal area.
- Taxon
- anisoptera thuriferaAnisoptera thuriferat0
- Outcome
- Logging commonly removes 25 - 40 percentnof the stand basal areae0
- Value
- 25 - 40 percente0
Verbatim
e0“Logging commonly removes 25 - 40 percentnof the stand basal area”
t0“anisoptera thurifera”
Claim · model-written summary
Removal of over 70 percent basal area minimized replenishment capacity.
- Taxon
- anisoptera thuriferaAnisoptera thuriferat0
- Outcome
- where more than 70 percent of thenbasal area is removed, few residuals are retained and the capacity to replenishnlarge disturbed areas is minimized.e0
- Direction
- minimizede0
- Qualifier
- where more than 70 percent of thenbasal area is removed, few residuals are retained and the capacity to replenishnlarge disturbed areas is minimized.e0
- Setting
- where more than 70 percent of thenbasal area is removed, few residuals are retained and the capacity to replenishnlarge disturbed areas is minimized.e0
Verbatim
e0“where more than 70 percent of thenbasal area is removed, few residuals are retained and the capacity to replenishnlarge disturbed areas is minimized.”
t0“anisoptera thurifera”
Claim · model-written summary
Low intensity logging retained original forest species composition.
- Taxon
- anisoptera thuriferaAnisoptera thuriferat0
- Treatment
- low intensity logginge0
- Outcome
- with low intensity logging, speciesncomposition of the original forest is retained.e0
Not reportedComparatorDirection
Verbatim
e0“with low intensity logging, speciesncomposition of the original forest is retained.”
t0“anisoptera thurifera”
Claim · model-written summary
Logging increased A. thurifera populations at some sites.
- Taxon
- A. thuriferae0
- Treatment
- logginge0
- Outcome
- the effect of loggingnwas found to increase A. thurifera populations over timee0
- Direction
- increasee0
Not reportedComparator
Verbatim
e0“the effect of loggingnwas found to increase A. thurifera populations over time”
Claim · model-written summary
Logging increased residual tree growth at some sites.
- Taxon
- anisoptera thuriferaAnisoptera thuriferat0
- Outcome
- as well as in increasedngrowth of the residual trees.e0
- Direction
- increasede0
Not reportedTreatmentComparator
Verbatim
e0“as well as in increasedngrowth of the residual trees.”
t0“anisoptera thurifera”
Claim · model-written summary
Most A. thurifera trees flowered in the late dry to early wet season.
- Taxon
- anisoptera thuriferaAnisoptera thuriferat0
- Outcome
- most tend to flower at the late dry period and thenearly wet season, which is between August and November.e0
Verbatim
e0“most tend to flower at the late dry period and thenearly wet season, which is between August and November.”
t0“anisoptera thurifera”
Claim · model-written summary
A. thurifera flowered and fruited more regularly than many other dipterocarps.
Verbatim
e0“A.nthurifera has a more regular flowering and fruiting pattern than many otherndipterocarps.”
Claim · model-written summary
Mast fruiting occurred every three to five years with sporadic annual reproduction otherwise.
- Taxon
- anisoptera thuriferaAnisoptera thuriferat0
- Outcome
- Mast fruiting occurs every three to five years but otherwise there isnsporadic annual flowering and fruiting.e0
- Value
- three to five yearse0
Verbatim
e0“Mast fruiting occurs every three to five years but otherwise there isnsporadic annual flowering and fruiting.”
t0“anisoptera thurifera”
Claim · model-written summary
Community flowering and fruiting lasted at most nine months.
- Taxon
- anisoptera thuriferaAnisoptera thuriferat0
- Outcome
- The community flowering andnsubsequent fruiting lasts a maximum of nine monthse0
- Value
- nine monthse0
Verbatim
e0“The community flowering andnsubsequent fruiting lasts a maximum of nine months”
t0“anisoptera thurifera”
Claim · model-written summary
Seed production depended on parent tree size and flowering intensity, with the most productive size class above 50 and below 90 cm dbh.
- Taxon
- anisoptera thuriferaAnisoptera thuriferat0
- Outcome
- quantity and quality of seed production depended on parent tree size and thenflowering intensity. The most productive size class was stems larger than 50 butnl 90 cm dbh.e0
- Qualifier
- quantity and quality of seed production depended on parent tree size and thenflowering intensity. The most productive size class was stems larger than 50 butnl 90 cm dbh.e0
- Setting
- quantity and quality of seed production depended on parent tree size and thenflowering intensity. The most productive size class was stems larger than 50 butnl 90 cm dbh.e0
Not reportedDirection
Verbatim
e0“quantity and quality of seed production depended on parent tree size and thenflowering intensity. The most productive size class was stems larger than 50 butnl 90 cm dbh.”
t0“anisoptera thurifera”
Claim · model-written summary
Most seeds dispersed within ten metres of the parent crown.
- Taxon
- anisoptera thuriferaAnisoptera thuriferat0
- Outcome
- majority of the seeds were dispersednwithin ten metres radius of the parent tree crown.e0
- Value
- ten metrese0
Verbatim
e0“majority of the seeds were dispersednwithin ten metres radius of the parent tree crown.”
t0“anisoptera thurifera”
Claim · model-written summary
Seed viability rose with maturity and was highest immediately after seed fall.
- Taxon
- anisoptera thuriferaAnisoptera thuriferat0
- Outcome
- viability increased according to seed maturity and was highestnimmediately upon seed fall.e0
- Direction
- increasede0
- Qualifier
- viability increased according to seed maturity and was highestnimmediately upon seed fall.e0
- Setting
- viability increased according to seed maturity and was highestnimmediately upon seed fall.e0
Verbatim
e0“viability increased according to seed maturity and was highestnimmediately upon seed fall.”
t0“anisoptera thurifera”
Claim · model-written summary
Seeds stored 21 days lost viability, whereas those stored 14 days retained 68 percent viability.
- Taxon
- anisoptera thuriferaAnisoptera thuriferat0
- Treatment
- stored for 14 dayse0
- Outcome
- those stored for 21 days all lostnviability but those stored for 14 days had 68 percent viability.e0
- Value
- 68 percente0
- Comparator
- stored for 21 dayse0
Not reportedDirection
Verbatim
e0“those stored for 21 days all lostnviability but those stored for 14 days had 68 percent viability.”
t0“anisoptera thurifera”
Claim · model-written summary
Predation began early in seed development and continued through fruiting, affecting 50 to 65 percent before dispersal and 85 percent overall.
- Taxon
- anisoptera thuriferaAnisoptera thuriferat0
- Outcome
- pre-dispersalnpredation was high affecting 50-65 percent of the total seeds produced in anseason.e0
- Value
- 50-65 percente0
Verbatim
e0“pre-dispersalnpredation was high affecting 50-65 percent of the total seeds produced in anseason.”
t0“anisoptera thurifera”
Claim · model-written summary
Seedling density averaged 0.42 seedlings per square metre and depended on fruiting intensity and stand density.
- Taxon
- anisoptera thuriferaAnisoptera thuriferat0
- Outcome
- number of seedlings regeneratingndepended on the intensity of fruiting and stand density, averaging at 0.42nseedlings m-2e0
- Value
- 0.42nseedlings m-2e0
- Qualifier
- number of seedlings regeneratingndepended on the intensity of fruiting and stand density, averaging at 0.42nseedlings m-2e0
- Setting
- number of seedlings regeneratingndepended on the intensity of fruiting and stand density, averaging at 0.42nseedlings m-2e0
Not reportedDirection
Verbatim
e0“number of seedlings regeneratingndepended on the intensity of fruiting and stand density, averaging at 0.42nseedlings m-2”
t0“anisoptera thurifera”
Claim · model-written summary
At Oomsis, 64 percent of original seedlings persisted for three years and 79 percent of new recruits survived seven months.
- Taxon
- anisoptera thuriferaAnisoptera thuriferat0
- Outcome
- 64 percent of the original seedlings persisted over three years, and 79npercent of those recruited in December 2001 survived after seven months.e0
- Value
- 64 percente0
Verbatim
e0“64 percent of the original seedlings persisted over three years, and 79npercent of those recruited in December 2001 survived after seven months.”
t0“anisoptera thurifera”
Claim · model-written summary
Seedling height growth averaged 7 cm per year and was greatest for younger seedlings and higher light.
- Taxon
- anisoptera thuriferaAnisoptera thuriferat0
- Outcome
- Seedling height growth averaged at 7 cm year-1 and thenhighest growth rates were recorded in younger seedlings and among thosengrowing under higher light levels.e0
- Value
- 7 cm year-1e0
Verbatim
e0“Seedling height growth averaged at 7 cm year-1 and thenhighest growth rates were recorded in younger seedlings and among thosengrowing under higher light levels.”
t0“anisoptera thurifera”
Claim · model-written summary
Seedlings grew fastest under 30 percent relative light intensity.
- Taxon
- anisoptera thuriferaAnisoptera thuriferat0
- Treatment
- 30 percent RLIe0
- Outcome
- highest growth rates were attainednunder the 30 percent RLI.e0
- Direction
- higheste0
Not reportedComparator
Verbatim
e0“highest growth rates were attainednunder the 30 percent RLI.”
t0“anisoptera thurifera”
Claim · model-written summary
High thinning produced the highest A. thurifera growth rates, while recruitment and mortality showed no significant treatment effect.
- Taxon
- A. thuriferae0
- Treatment
- high thinning treatmentse0
- Outcome
- highest growth rates for A. thurifera werenattained under the high thinning treatments.e0
- Direction
- higheste0
Not reportedComparator
Verbatim
e0“highest growth rates for A. thurifera werenattained under the high thinning treatments.”