Towards better estimates of carbon stocks in Borneo's logged-over Dipterocarp forests

2020 ◽  
Vol 345 ◽  
pp. 101-102
Author(s):  
Andes Hamuraby ROZAK
Keyword(s):  
Tropical Forests ◽  
Selective Logging ◽  
Long Term Effects ◽  
Logging Damage ◽  
Canopy Opening ◽  
Dipterocarp Forests ◽  
C Stocks ◽  
Large Trees ◽  
Main Driver

Tropical forests are a major reservoir of biodiversity and carbon (C), playing a pivotal role in global ecosystem function and climate regulation. However, most tropical forests, especially Borneo's forests in Southeast Asia, are under intense pressure and threatened by human activities such as logging, mining, agriculture and conversion to industrial plantations. Selective logging is known to reduce both above- and below-ground biomass by removing selected large trees, while increasing deadwood stocks through collateral logging damage and creating large gaps in the canopy. The extent of incidental damage, canopy opening and the rate of C recovery were shown to be primarily related to logging intensity. This thesis assesses the long-term effects of logging intensity on five main C pools in Dipterocarp forests in northern Borneo (Malinau District, North Kalimantan) along a logging intensity gradient ranging from 0 to 57% of initial biomass removed in 1999/2000. Our results showed that total C stocks 16 years after logging ranged from 218-554 Mg C/ha with an average of 314 Mg C/ha. A difference of 95 Mg C/ha was found between low logging intensity (< 2.1% of initial biomass lost) and high logging intensity (> 19%). Most C (approx. 77%) was found in living trees, followed by soil (15%), deadwood (6%) and a small fraction in litter (1%). The imprint of logging intensity was still detectable 16 years after logging. Logging intensity was thus shown to be the main driver explaining the reduction of AGC>20, BGC>20, in deadwood and total C stocks and an increase in deadwood. Our results quantify the long-term effects of logging on forest C stocks, especially in AGC and deadwood. High logging intensity (50% reduction of initial biomass) reduced total C stocks by 27%. AGC recovery was lower in high logging intensity plots, suggesting lowered forest resilience to logging. Our study showed that keeping logging intensity below 20% of the initial biomass can limit the long-term effects of logging on AGC and deadwood stocks.

scholarly journals Stand Structure and Composition 32 Years after Precommercial Thinning Treatments in a Mixed Northern Conifer Stand in Central Maine

2011 ◽  
Vol 28 (2) ◽  
pp. 92-96 ◽  
Author(s):  
Aaron R. Weiskittel ◽  
Laura S. Kenefic ◽  
Rongxia Li ◽  
John Brissette
Keyword(s):  
Stand Structure ◽  
Abies Balsamea ◽  
Basal Area ◽  
Long Term Effects ◽  
Mixed Species ◽  
Precommercial Thinning ◽  
Large Trees ◽  
Stand Attributes ◽  
And Control

Abstract The effects of four precommercial thinning (PCT) treatments on an even-aged northern conifer stand in Maine were investigated by examining stand structure and composition 32 years after treatment. Replicated treatments applied in 1976 included: (1) control (no PCT), (2) row thinning (rowthin; 5-ft-wide row removal with 3-ft-wide residual strips), (3) row thinning with crop tree release (rowthin+CTR; 5-ft-wide row removal with crop tree release at 8-ft intervals in 3-ft-wide residual strips), and (4) crop tree release (CTR; release of selected crop trees at 8×8-ft intervals). PCT plots had more large trees and fewer small trees than the control in 2008. There were no other significant differences between the rowthin and control. The rowthin+CTR and CTR treatments had lower total and hardwood basal area (BA) and higher merchantable conifer BA than the control. CTR also resulted in more red spruce (Picea rubens [Sarg.]) and less balsam fir (Abies balsamea [L.]) than the other treatments. Although stand structures for rowthin+CTR and CTR were similar, the percentage of spruce in CTR was greater. Although the less-intensive rowthin+CTR treatment may provide many of the same benefits as CTR, the latter would be the preferred treatment if increasing the spruce component of a stand is an objective. Overall, early thinning treatments were found to have long-term effects on key stand attributes, even more than 30 years after treatment in areas with mixed species composition and moderate site potential.

Effects of partial bark removal on the growth of Pacific yew

1994 ◽  
Vol 24 (4) ◽  
pp. 860-862 ◽  
Author(s):  
Don Minore ◽  
Howard G. Weatherly
Keyword(s):  
Radial Growth ◽  
Stand Structure ◽  
Strongly Correlated ◽  
Long Term Effects ◽  
Canopy Density ◽  
Logging Damage ◽  
Standing Trees ◽  
Thermal Cover ◽  
Whole Tree

Whole-tree harvest of Pacific yew (Taxusbrevifolia Nutt.) to provide bark for production of the new anticancer drug taxol may adversely affect stand structure where yews provide thermal cover, browse, or riparian benefits. Harvesting only a portion of the bark on standing trees would maintain existing stand structure if the affected trees continued to grow, but partial bark removal seldom has been applied because its long-term effects are unknown. We measured 121 yews that had been scarred by windthrow or logging damage 3–92 years ago and found that their growth did not differ significantly from the growth of nearby unscarred yews. Radial growth of the scarred trees was strongly correlated with growth before scarring; it was slightly associated with overstory canopy density, elevation, and the amount of bark removed. Partial bark removal from one side of the tree probably will not seriously affect the growth of Pacific yew if less than 50% of the bark is removed.

scholarly journals The impact of long dry periods on the aboveground biomass in tropical forests: 20 years of monitoring

2020 ◽  
Author(s):  
Milton Serpa de Meira-Junior ◽  
José Roberto Rodrigues Pinto ◽  
Natália Oliveira Ramos ◽  
Eder Pereira Miguel ◽  
Ricardo de Oliveira Gaspar ◽  
...  
Keyword(s):  
Tropical Forests ◽  
Aboveground Biomass ◽  
Carbon Stocks ◽  
Stem Density ◽  
Biomass Carbon ◽  
Neotropical Forests ◽  
Aboveground Carbon ◽  
Large Trees ◽  
The Impact

Abstract Background Long-term studies of community and population dynamics indicate that abrupt disturbances often catalyse changes in vegetation and carbon stocks. These disturbances include the opening of clearings, flooding, rainfall seasonality, and drought, as well as fire and direct human disturbance. Such events may be super-imposed on longer-term trends in disturbance, such as those associated with climate change (heating, drying), as well as resources. Intact neotropical forests have recently experienced increased drought frequency and fire, on top of pervasive increases in atmospheric CO2 concentrations, but we lack long-term records of responses to such changes especially in the critical transitional areas at the interface of forest and savanna biomes. Here, we present results from 20 years monitoring a valley forest (moist tropical forest outlier) in central Brazil. The forest has experienced multiple drought events and includes plots which have and which have not experienced fire. We focus on how forest structure (stem density and aboveground biomass carbon) and dynamics (stem and biomass mortality and recruitment) have responded to these disturbance regimes. ResultsOverall, the biomass carbon stock increased due to the growth of the trees already present in the forest, without any increase in the overall number of tree stems. Over time, both recruitment and especially mortality of trees tended to increase, and periods of prolonged drought in particular resulted in increased mortality rates of larger trees. This increased mortality was in turn responsible for a decline in aboveground carbon toward the end of the monitoring period. Fire in 2010, which occurred in only some of our plots, tended to exacerbate the trends of increasing mortality and losses of biomass carbon. Conclusion Prolonged droughts influence the mortality of large trees, leading to a decline in aboveground carbon stocks. Here, and in other neotropical forests, recent droughts are capable of shutting down and reversing biomass carbon sinks. These new results add to evidence that anthropogenic climate changes are already adversely impacting tropical forests.

scholarly journals Fire-derived phosphorus fertilization of African tropical forests

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Marijn Bauters ◽  
Travis W. Drake ◽  
Sasha Wagner ◽  
Simon Baumgartner ◽  
Isaac A. Makelele ◽  
...  
Keyword(s):  
Tropical Forests ◽  
Phosphorus Fertilization ◽  
Secondary Forests ◽  
Long Term Effects ◽  
Anthropogenic Pressures ◽  
Forest Canopies ◽  
Land Use Conversion ◽  
Forest Regrowth ◽  
Equatorial Forest

AbstractCentral African tropical forests face increasing anthropogenic pressures, particularly in the form of deforestation and land-use conversion to agriculture. The long-term effects of this transformation of pristine forests to fallow-based agroecosystems and secondary forests on biogeochemical cycles that drive forest functioning are poorly understood. Here, we show that biomass burning on the African continent results in high phosphorus (P) deposition on an equatorial forest via fire-derived atmospheric emissions. Furthermore, we show that deposition loads increase with forest regrowth age, likely due to increasing canopy complexity, ranging from 0.4 kg P ha−1 yr−1 on agricultural fields to 3.1 kg P ha−1 yr−1 on old secondary forests. In forest systems, canopy wash-off of dry P deposition increases with rainfall amount, highlighting how tropical forest canopies act as dynamic reservoirs for enhanced addition of this essential plant nutrient. Overall, the observed P deposition load at the study site is substantial and demonstrates the importance of canopy trapping as a pathway for nutrient input into forest ecosystems.

scholarly journals The impact of long dry periods on the aboveground biomass in tropical forests: 20 years of monitoring

2020 ◽  
Author(s):  
Milton Serpa de Meira-Junior ◽  
José Roberto Rodrigues Pinto ◽  
Natália Oliveira Ramos ◽  
Eder Pereira Miguel ◽  
Ricardo de Oliveira Gaspar ◽  
...  
Keyword(s):  
Tropical Forests ◽  
Aboveground Biomass ◽  
Carbon Stocks ◽  
Stem Density ◽  
Biomass Carbon ◽  
Neotropical Forests ◽  
Aboveground Carbon ◽  
Large Trees ◽  
The Impact

Abstract Background Long-term studies of community and population dynamics indicate that abrupt disturbances often catalyse changes in vegetation and carbon stocks. These disturbances include the opening of clearings, flooding, rainfall seasonality, and drought, as well as fire and direct human disturbance. Such events may be super-imposed on longer-term trends in disturbance, such as those associated with climate change (heating, drying), as well as resources. Intact neotropical forests have recently experienced increased drought frequency and fire, on top of pervasive increases in atmospheric CO 2 concentrations, but we lack long-term records of responses to such changes especially in the critical transitional areas at the interface of forest and savanna biomes. Here, we present results from 20 years monitoring a valley forest (moist tropical forest outlier) in central Brazil. The forest has experienced multiple drought events and includes plots which have and which have not experienced fire. We focus on how forest structure (stem density and aboveground biomass carbon) and dynamics (stem and biomass mortality and recruitment) have responded to these disturbance regimes. Results Overall, the biomass carbon stock increased due to the growth of the trees already present in the forest, without any increase in the overall number of tree stems. Over time, both recruitment and especially mortality of trees tended to increase, and periods of prolonged drought in particular resulted in increased mortality rates of larger trees. This increased mortality was in turn responsible for a decline in aboveground carbon toward the end of the monitoring period. Fire in 2010, which occurred in only some of our plots, tended to exacerbate the trends of increasing mortality and losses of biomass carbon. Conclusion Prolonged droughts influence the mortality of large trees, leading to a decline in aboveground carbon stocks. Here, and in other neotropical forests, recent droughts are capable of shutting down and reversing biomass carbon sinks. These new results add to evidence that anthropogenic climate changes are already adversely impacting tropical forests.

scholarly journals The Sabah Biodiversity Experiment: a long-term test of the role of tree diversity in restoring tropical forest structure and functioning

2011 ◽  
Vol 366 (1582) ◽  
pp. 3303-3315 ◽  
Author(s):  
Andy Hector ◽  
Christopher Philipson ◽  
Philippe Saner ◽  
Juliette Chamagne ◽  
Dzaeman Dzulkifli ◽  
...  
Keyword(s):  
Species Diversity ◽  
Forest Structure ◽  
Ecosystem Functioning ◽  
Initial Conditions ◽  
Selective Logging ◽  
Long Term Results ◽  
Primary Forest ◽  
Large Trees ◽  
The Relationship

Relatively, little is known about the relationship between biodiversity and ecosystem functioning in forests, especially in the tropics. We describe the Sabah Biodiversity Experiment: a large-scale, long-term field study on the island of Borneo. The project aims at understanding the relationship between tree species diversity and the functioning of lowland dipterocarp rainforest during restoration following selective logging. The experiment is planned to run for several decades (from seed to adult tree), so here we focus on introducing the project and its experimental design and on assessing initial conditions and the potential for restoration of the structure and functioning of the study system, the Malua Forest Reserve. We estimate residual impacts 22 years after selective logging by comparison with an appropriate neighbouring area of primary forest in Danum Valley of similar conditions. There was no difference in the alpha or beta species diversity of transect plots in the two forest types, probably owing to the selective nature of the logging and potential effects of competitive release. However, despite equal total stem density, forest structure differed as expected with a deficit of large trees and a surfeit of saplings in selectively logged areas. These impacts on structure have the potential to influence ecosystem functioning. In particular, above-ground biomass and carbon pools in selectively logged areas were only 60 per cent of those in the primary forest even after 22 years of recovery. Our results establish the initial conditions for the Sabah Biodiversity Experiment and confirm the potential to accelerate restoration by using enrichment planting of dipterocarps to overcome recruitment limitation. What role dipterocarp diversity plays in restoration only will become clear with long-term results.

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