Organic Termite Repellents Tested Against Cryptotermes Brevis Walker

The high resistance to decay and insect attack of some woods which makes them of such great value for building and the construction of furniture for use in the Tropics, is due to the presence in the heartwood of each species of a comparatively minute amount of some unique chemical. Such chemicals appear to have little or no survival value for the tree itself, and indeed often result in its early elimination by selective cutting in virgin tropical forests. The less desirable woods, however, may be given at least superficial protection by painting, spraying, submergence, or pressure-impregnation with such extracted constituents of resistant woods, or with other chemicals synthesized in the laboratory.

Download Full-text

The Atmospheric Component of Biogeochemical Cycles in the Amazon Basin

The Biogeochemistry of the Amazon Basin ◽

10.1093/oso/9780195114317.003.0006 ◽

2001 ◽

Author(s):

Paulo Artaxo

Keyword(s):

Land Use ◽

Tropical Forests ◽

Amazon Basin ◽

Aerosol Particles ◽

Trace Gases ◽

Biogeochemical Cycles ◽

Dry Season ◽

Earth System ◽

The Earth ◽

The Tropics

Tropical forests, with their high biological activity, have the potential to emit large amounts of trace gases and aerosol particles to the atmosphere. The accelerated development and land clearing that is occurring in large areas of the Amazon basin suggest that anthropogenic effects on natural biogeochemical cycles are already occurring (Gash et al. 1996). The atmosphere plays a key role in this process. The tropics are the part of the globe with the most rapidly growing population, the most dramatic industrial expansion and the most rapid and pervasive change in land use and land cover. Also the tropics contain the largest standing stocks of terrestrial vegetation and have the highest rates of photosynthesis and respiration. It is likely that changes in tropical land use will have a profound impact on the global atmosphere (Andreae 1998, Andreae and Crutzen 1997). A significant fraction of nutrients are transported or dislocated through the atmosphere in the form of trace gases, aerosol particles, and rainwater (Keller et al. 1991). Also the global effects of carbon dioxide, methane, nitrous oxide, and other trace gases have in the forest ecosystems a key partner. The large emissions of isoprene, terpenes, and many other volatile organic compounds could impact carbon cycling and the production of secondary aerosol particles over the Amazon region. Vegetation is a natural source of many types of aerosol particles that play an important role in the radiation budget over large areas (Artaxo et al. 1998). There are 5 major reservoirs in the Earth system: atmosphere, biosphere (vegetation, animals), soils, hydrosphere (oceans, lakes, rivers, groundwater), and the lithosphere (Earth crust). Elemental cycles of carbon, oxygen, nitrogen, sulfur, phosphorus, and other elements interact with the different reservoirs of the Earth system. The carbon cycle has important aspects in tropical forests due to the large amount of carbon stored in the tropical forests and the high rate of tropical deforestation (Jacob 1999). In Amazonia there are two very different atmospheric conditions: the wet season (mostly from November to June) and the dry season (July-October) (see Marengo and Nobre, this volume). Biomass burning emissions dominate completely the atmospheric concentrations over large areas of the Amazon basin during the dry season (Artaxo et al. 1988).

Download Full-text

Rarity of monodominance in hyperdiverse Amazonian forests

Scientific Reports ◽

10.1038/s41598-019-50323-9 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 6

Author(s):

Hans ter Steege ◽

Terry W. Henkel ◽

Nora Helal ◽

Beatriz S. Marimon ◽

Ben Hur Marimon-Junior ◽

...

Keyword(s):

Tropical Forests ◽

Tree Species ◽

Life History Traits ◽

Seed Mass ◽

Forest Patches ◽

Tropical Regions ◽

Single Tree ◽

The Tropics ◽

Amazonian Forests ◽

High Diversity

Abstract Tropical forests are known for their high diversity. Yet, forest patches do occur in the tropics where a single tree species is dominant. Such “monodominant” forests are known from all of the main tropical regions. For Amazonia, we sampled the occurrence of monodominance in a massive, basin-wide database of forest-inventory plots from the Amazon Tree Diversity Network (ATDN). Utilizing a simple defining metric of at least half of the trees ≥ 10 cm diameter belonging to one species, we found only a few occurrences of monodominance in Amazonia, and the phenomenon was not significantly linked to previously hypothesized life history traits such wood density, seed mass, ectomycorrhizal associations, or Rhizobium nodulation. In our analysis, coppicing (the formation of sprouts at the base of the tree or on roots) was the only trait significantly linked to monodominance. While at specific locales coppicing or ectomycorrhizal associations may confer a considerable advantage to a tree species and lead to its monodominance, very few species have these traits. Mining of the ATDN dataset suggests that monodominance is quite rare in Amazonia, and may be linked primarily to edaphic factors.

Download Full-text

SMOS-IC L-VOD reveals that tropical forests did not recover from the strong 2015–2016 El Niño event

10.5194/egusphere-egu2020-4020 ◽

2020 ◽

Author(s):

Lei Fan ◽

Jean-pierre Wigneron ◽

Philippe Ciais ◽

Ana Bastos ◽

Martin Brandt ◽

...

Keyword(s):

Tropical Forests ◽

Land Surface ◽

Atmospheric Transport ◽

Low Frequency ◽

Climatic Conditions ◽

Severe Drought ◽

Global Carbon Budget ◽

Large Spread ◽

The Tropics ◽

Atmospheric Inversions

Severe drought and extreme heat associated with the 2015&#8211;2016 El Ni&#241;o event have led to large carbon emissions from the tropical vegetation to the atmosphere. With the return to normal climatic conditions in 2017, tropical forest aboveground carbon (AGC) stocks are expected to partly recover due to increased productivity, but the intensity and spatial distribution of this recovery are unknown. Simulations from land-surface models used in the global carbon budget (GCB) suggest a strong reinvigoration of the tropical land sink after the 2015&#8211;2016 El Ni&#241;o. However, models and atmospheric inversions display large divergences in tropical CO2 fluxes during the 2017 recovery event. For instance, models predict a total net land sink recovery (2017 sink minus the 2015&#8211;2016 average sink) ranging from 0.3 to 2.6 Pg C, and the land sink recovery estimated from five atmospheric inversions ranges from &#8722;0.08 to +1.92 Pg C. The results of different inversions show a large spread in the tropics due to the scarcity of stations and uncertainties in atmospheric transport simulations.We used low-frequency microwave satellite data (L-VOD) to feature precise monitoring of AGC changes and show that the AGC recovery of tropical ecosystems was slow and that by the end of 2017, AGC had not reached predrought levels of 20141. From 2014 to 2017, tropical AGC stocks decreased by 1.3 Pg C due to persistent AGC losses in Africa (-0.9 Pg C) and America (-0.5 Pg C). Pantropically, drylands recovered their carbon stocks to pre&#8211;El Ni&#241;o levels, but African and American humid forests did not, suggesting carryover effects from enhanced forest mortality.&#160;Reference<ol><li>J.-P. Wigneron, L. Fan, P. Ciais, A. Bastos, M. Brandt, J. Chave, S. Saatchi, A. Baccini, R. Fensholt, Tropical forests did not recover from the strong 2015&#8211;2016 El Ni&#241;o event. Science Advances. 6, eaay4603 (2020).</li> </ol>

Download Full-text

Securing tropical forest carbon: the contribution of protected areas to REDD

Oryx ◽

10.1017/s0030605310000542 ◽

2010 ◽

Vol 44 (3) ◽

pp. 352-357 ◽

Cited By ~ 60

Author(s):

Jörn P. W. Scharlemann ◽

Valerie Kapos ◽

Alison Campbell ◽

Igor Lysenko ◽

Neil D. Burgess ◽

...

Keyword(s):

Land Use ◽

Protected Areas ◽

Tropical Forests ◽

Carbon Emissions ◽

Protected Area ◽

Forest Cover ◽

Forest Degradation ◽

Protected Area Management ◽

Forest Loss ◽

The Tropics

AbstractForest loss and degradation in the tropics contribute 6–17% of all greenhouse gas emissions. Protected areas cover 217.2 million ha (19.6%) of the world’s humid tropical forests and contain c. 70.3 petagrams of carbon (Pg C) in biomass and soil to 1 m depth. Between 2000 and 2005, we estimate that 1.75 million ha of forest were lost from protected areas in humid tropical forests, causing the emission of 0.25–0.33 Pg C. Protected areas lost about half as much carbon as the same area of unprotected forest. We estimate that the reduction of these carbon emissions from ongoing deforestation in protected sites in humid tropical forests could be valued at USD 6,200–7,400 million depending on the land use after clearance. This is > 1.5 times the estimated spending on protected area management in these regions. Improving management of protected areas to retain forest cover better may be an important, although certainly not sufficient, component of an overall strategy for reducing emissions from deforestation and forest degradation (REDD).

Download Full-text

Estimating aboveground carbon density and its uncertainty in Borneo’s structurally complex tropical forests using airborne laser scanning

10.5194/bg-2018-74 ◽

2018 ◽

Cited By ~ 3

Author(s):

Tommaso Jucker ◽

Gregory P. Asner ◽

Michele Dalponte ◽

Philip Brodrick ◽

Christopher D. Philipson ◽

...

Keyword(s):

Tropical Forests ◽

Laser Scanning ◽

Canopy Cover ◽

Carbon Stocks ◽

Forest Carbon ◽

Airborne Laser Scanning ◽

Tropical Asia ◽

Airborne Laser ◽

Dipterocarp Forests ◽

The Tropics

Abstract. Borneo contains some of the world’s most biodiverse and carbon dense tropical forest, but this 750 000-km2 island has lost 62 % of its old-growth forests within the last 40 years. Efforts to protect and restore the remaining forests of Borneo hinge on recognising the ecosystem services they provide, including their ability to store and sequester carbon. Airborne Laser Scanning (ALS) is a remote sensing technology that allows forest structural properties to be captured in great detail across vast geographic areas. In recent years ALS has been integrated into state-wide assessment of forest carbon in Neotropical and African regions, but not yet in Asia. For this to happen, new regional models, need to be developed for estimating carbon stocks from ALS in tropical Asia, as the forests of this region are structurally and compositionally distinct from those found elsewhere in the tropics. By combining ALS imagery with data from 173 permanent forest plots spanning the lowland rain forests of Sabah, on the island of Borneo, we develop a simple-yet-general model for estimating forest carbon stocks using ALS-derived canopy height and canopy cover as input metrics. An advanced feature of this new model is the propagation of uncertainty in both ALS- and ground-based data, allowing uncertainty in hectare-scale estimates of carbon stocks to be quantified robustly. We show that the model effectively captures variation in aboveground carbons stocks across extreme disturbance gradients spanning tall dipterocarp forests and heavily logged regions, and clearly outperforms existing ALS-based models calibrated for the tropics, as well as currently available satellite-derived products. Our model provides a simple, generalised and effective approach for mapping forest carbon stocks in Borneo, and underpins ongoing efforts to safeguard and facilitate the restoration of its unique tropical forests.

Download Full-text

Persistent collapse of biomass in Amazonian forest edges following deforestation leads to unaccounted carbon losses

Science Advances ◽

10.1126/sciadv.aaz8360 ◽

2020 ◽

Vol 6 (40) ◽

pp. eaaz8360 ◽

Cited By ~ 2

Author(s):

Celso H. L. Silva Junior ◽

Luiz E. O. C. Aragão ◽

Liana O. Anderson ◽

Marisa G. Fonseca ◽

Yosio E. Shimabukuro ◽

...

Keyword(s):

Remote Sensing ◽

Tropical Forests ◽

Forest Fragmentation ◽

Edge Effect ◽

Carbon Emissions ◽

Forest Edges ◽

Amazonian Forest ◽

Primary Driver ◽

The Tropics ◽

Carbon Losses

Deforestation is the primary driver of carbon losses in tropical forests, but it does not operate alone. Forest fragmentation, a resulting feature of the deforestation process, promotes indirect carbon losses induced by edge effect. This process is not implicitly considered by policies for reducing carbon emissions in the tropics. Here, we used a remote sensing approach to estimate carbon losses driven by edge effect in Amazonia over the 2001 to 2015 period. We found that carbon losses associated with edge effect (947 Tg C) corresponded to one-third of losses from deforestation (2592 Tg C). Despite a notable negative trend of 7 Tg C year−1 in carbon losses from deforestation, the carbon losses from edge effect remained unchanged, with an average of 63 ± 8 Tg C year−1. Carbon losses caused by edge effect is thus an additional unquantified flux that can counteract carbon emissions avoided by reducing deforestation, compromising the Paris Agreement’s bold targets.

Download Full-text

Composition and Properties of the Natural Aerosol over the Boreal and Tropical Forests

10.5194/egusphere-egu2020-11662 ◽

2020 ◽

Author(s):

Hans-Christen Hansson ◽

Paulo Artaxo ◽

Meinrat Andreae ◽

Markku Kulmala

Keyword(s):

Tropical Forests ◽

Atmospheric Chemistry ◽

Boreal Forests ◽

Cloud Condensation Nuclei ◽

Particle Formation ◽

Climate System ◽

Atmospheric Composition ◽

Cloud Formation ◽

Aerosol Composition ◽

The Tropics

We, together with 50 of our colleagues present a review on the interaction between tropical and boreal forests and the atmosphere, especially addressing their influence in the climate system. With its emissions of VOCs, aerosols and trace gases, with strong atmosphere interactions, forests are a key component of the climate system. These emissions and atmospheric processing regulates atmospheric chemistry and are the major source of cloud condensation nuclei (CCN) affecting cloud formation and development, and thus temperature and precipitation. Emissions from forests are thus closely connected to the hydrological and the carbon cycles, being &#160;an essential integrated part of the climate system.In terms of meteorology, tropical and boreal forests are very different. Temperature, solar radiation, precipitation, evapotranspiration, albedo, cloud structure and cover, convection etc., are all very different. However, the aerosols in the two systems show similarities as Primary Biological Aerosol Particles are the major component (70%) of coarse mode particles in Amazonia while Secondary Organic Aerosol in the tropics are mainly isoprene driven giving a slightly more hygroscopic SOA than the boreal monoterpene driven SOA. The organics constitutes 70 to 85% of PM1 mass for both boreal and tropical forests. In Amazonia, sulfates, nitrates and BC shows very low concentrations, while the boreal sites shows 2-3 times higher concentrations. The Siberian continental site and Amazonian site show remarkable similarities in the lack of new particle formation (NPF) which will be &#160;discussed.In the tropics dry season and boreal spring and early summer, increasing biomass burning emissions in both forest types dominates the aerosol composition, with high OC and BC concentrations while anthropogenic pollution influences boreal forest atmospheric composition during wintertime. The changes in diffuse to direct radiation due to scattering aerosols has important effects in tropical forests but minor in boreal, enhancing the net ecosystem exchange by 30% and 10% respectively. Thus the natural forest emissions affects the direct as well as the indirect forcing.An Amazonia high altitude NPF process chain was recently observed at the top of the troposphere, and is an interesting interaction between forest emissions, cloud transport and processing and particle formation and aging at high altitudes that are brought back to the boundary layer, populating the CCN. For boreal forests, the complex relationship between GPP, BVOC, SOA, CCN, clouds, radiation, temperature and CO2 show multiple pathways and feedbacks, and some of them can be quantified. All showing the complexity of the interaction between forests, atmosphere and climate.

Download Full-text

Lessons from a Caterpillar Plague in London's Berkeley Square

Environmental Conservation ◽

10.1017/s0376892900001314 ◽

1975 ◽

Vol 2 (3) ◽

pp. 171-177 ◽

Cited By ~ 2

Author(s):

Denis F. Owen

Keyword(s):

Tropical Forests ◽

Direct Evidence ◽

Population Stability ◽

Trial And Error ◽

Mature Trees ◽

Plant Feeding ◽

Diverse Communities ◽

Considerable Controversy ◽

Precise Relationship ◽

The Tropics

Plagues of caterpillars and other plant-feeding insects tend to occur where trees and other plants grow as man-made monocultures. Herbivorous insects rarely cause extensive damage to mature trees in tropical forests; but even in the tropics, outbreaks are frequent wherever trees of the same species are grown together—as for example along roadways and in built-up areas. In Africa, in particular, peasant cultivators growing their own food tend to plant a variety of species in the same plot, and it is suggested that these people have found by trial and error that polycultures are more resistant to insect damage than are monocultures. English flower-gardeners maintain polycultures in their herbaceous borders and are rarely troubled by insects, but vegetables are now grown as pure stands. This probably leads to a build-up of pests and a need to use pesticides, which of course is encouraged by the gardening and pesticide industries.Although there remains considerable controversy over the precise relationship between species diversity and population stability, there is much circumstantial and some direct evidence that plagues of plant-feeding insects are much more likely in pure stands of vegetation than in diverse communities. What might be called the community ecology of peasant cultivation is little understood, and there is an urgent need for research before more and more land is converted to monocultures.

Download Full-text

Carbon Dynamics in a Human-Modified Tropical Forest: A Case Study Using Multi-Temporal LiDAR Data

Remote Sensing ◽

10.3390/rs12030430 ◽

2020 ◽

Vol 12 (3) ◽

pp. 430 ◽

Cited By ~ 2

Author(s):

Yhasmin Mendes de Moura ◽

Heiko Balzter ◽

Lênio S. Galvão ◽

Ricardo Dalagnol ◽

Fernando Espírito-Santo ◽

...

Keyword(s):

Carbon Cycle ◽

Tropical Forests ◽

Carbon Dynamics ◽

Carbon Stocks ◽

Forest Carbon ◽

Selective Logging ◽

Carbon Accounting ◽

Lidar Data ◽

Multi Temporal ◽

The Tropics

Tropical forests hold significant amounts of carbon and play a critical role on Earth´s climate system. To date, carbon dynamics over tropical forests have been poorly assessed, especially over vast areas of the tropics that have been affected by some type of disturbance (e.g., selective logging, understory fires, and fragmentation). Understanding the multi-temporal dynamics of carbon stocks over human-modified tropical forests (HMTF) is crucial to close the carbon cycle balance in the tropics. Here, we used multi-temporal and high-spatial resolution airborne LiDAR data to quantify rates of carbon dynamics over a large patch of HMTF in eastern Amazon, Brazil. We described a robust approach to monitor changes in aboveground forest carbon stocks between 2012 and 2018. Our results showed that this particular HMTF lost 0.57 m·yr−1 in mean forest canopy height and 1.38 Mg·C·ha−1·yr−1 of forest carbon between 2012 and 2018. LiDAR-based estimates of Aboveground Carbon Density (ACD) showed progressive loss through the years, from 77.9 Mg·C·ha−1 in 2012 to 53.1 Mg·C·ha−1 in 2018, thus a decrease of 31.8%. Rates of carbon stock changes were negative for all time intervals analyzed, yielding average annual carbon loss rates of −1.34 Mg·C·ha−1·yr−1. This suggests that this HMTF is acting more as a source of carbon than a sink, having great negative implications for carbon emission scenarios in tropical forests. Although more studies of forest dynamics in HMTFs are necessary to reduce the current remaining uncertainties in the carbon cycle, our results highlight the persistent effects of carbon losses for the study area. HMTFs are likely to expand across the Amazon in the near future. The resultant carbon source conditions, directly associated with disturbances, may be essential when considering climate projections and carbon accounting methods.

Download Full-text

Hysteresis of tropical forests in the 21st century

Nature Communications ◽

10.1038/s41467-020-18728-7 ◽

2020 ◽

Vol 11 (1) ◽

Author(s):

Arie Staal ◽

Ingo Fetzer ◽

Lan Wang-Erlandsson ◽

Joyce H. C. Bosmans ◽

Stefan C. Dekker ◽

...

Keyword(s):

Climate Change ◽

Tropical Forests ◽

Spatial Scales ◽

Regional Scale ◽

Climatic Conditions ◽

Change Scenario ◽

Amazon Forest ◽

Recent Climate ◽

Severe Climate Change ◽

The Tropics

Abstract Tropical forests modify the conditions they depend on through feedbacks at different spatial scales. These feedbacks shape the hysteresis (history-dependence) of tropical forests, thus controlling their resilience to deforestation and response to climate change. Here, we determine the emergent hysteresis from local-scale tipping points and regional-scale forest-rainfall feedbacks across the tropics under the recent climate and a severe climate-change scenario. By integrating remote sensing, a global hydrological model, and detailed atmospheric moisture tracking simulations, we find that forest-rainfall feedback expands the geographic range of possible forest distributions, especially in the Amazon. The Amazon forest could partially recover from complete deforestation, but may lose that resilience later this century. The Congo forest currently lacks resilience, but is predicted to gain it under climate change, whereas forests in Australasia are resilient under both current and future climates. Our results show how tropical forests shape their own distributions and create the climatic conditions that enable them.

Download Full-text