The role of earthworms in nitrogen and solute retention in a tropical forest in Sabah, Malaysia: a pilot study

Compounds of the 20 elements needed by living organisms are relatively soluble in water and therefore vulnerable to being leached and lost from terrestrial ecosystems during mineralization. Intact systems have thus acquired retention mechanisms that sequester nutrients and minimize losses. Such mechanisms should be particularly important where rainfall is very high but direct evidence of retention mechanisms in tropical forests is scarce (Snaddon et al. 2012, Turner et al. 2007).

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Tropical Forests Natural History, Diversity, and Potentiality as Theatres of Human Adaptation and Negotiation

Tropical Forests in Prehistory, History, and Modernity ◽

10.1093/oso/9780198818496.003.0006 ◽

2019 ◽

Author(s):

Patrick Roberts

Keyword(s):

Tropical Forest ◽

Tropical Forests ◽

Homo Sapiens ◽

Terrestrial Ecosystems ◽

Black Pepper ◽

Wood Products ◽

Tropical Rainforests ◽

Cultural Significance ◽

Seasonally Dry ◽

Dry Tropical Forests

The above quote by the German poet, novelist, and painter Herman Hesse highlights the cultural significance of forests in nineteenth- and twentieth-century western culture as the ‘natural’ contrast to growing urban populations and industrial expansion. Hesse’s focus on the ‘ancient’ element of these environments is certainly valid in a tropical context, given that tropical forests are some of the oldest land-based environments on the planet, existing for over one thousand times longer than Homo sapiens (Upchurch and Wolf, 1987; Davis et al., 2005; Ghazoul and Shiel, 2010; Couvreur et al., 2011). This antiquity also makes them one of the richest and most diverse terrestrial ecosystems on the planet (Whitmore, 1998; Ghazoul and Shiel, 2010). Tropical rainforests, for example, contain over half of the world’s existing plant, animal, and insect species (Wilson, 1988). A significant portion of the developed world’s diet today originated in tropical forests—including staples such as squash and yams, spices such as black pepper, cinnamon, cloves, and sugar cane, and fruits including bananas, coconuts, avocados, mangoes, and tomatoes (Iriarte et al., 2007; Roberts et al., 2017a). Tropical forests also often provide ample freshwater for their inhabitants. However, despite popular perceptions of forests, and specifically tropical forests, as uniform, they are, in fact, highly variable across space and time. In tropical evergreen rainforests productivity is often primarily allocated to wood products, meaning that edible plants and animals for human subsistence have been considered lacking, or at least more difficult to extract, relative to more open tropical forest formations (Whitmore, 1998; Ghazoul and Shiel, 2010). Similarly, while evergreen tropical rainforests generally receive significant precipitation and freshwater, seasonally dry tropical forests are subject to sub-annual periods of aridity. Therefore, while archaeologists and anthropologists have tended to see ‘tropical forest’ as a uniform environmental block, it is important to explore the diversity within this category.

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Releases of carbon to the atmosphere from degradation of forests in tropical Asia

Canadian Journal of Forest Research ◽

10.1139/x91-017 ◽

1991 ◽

Vol 21 (1) ◽

pp. 132-142 ◽

Cited By ~ 43

Author(s):

R. A. Houghton

Keyword(s):

Southeast Asia ◽

Tropical Forest ◽

Tropical Forests ◽

Forest Biomass ◽

Terrestrial Ecosystems ◽

Tropical Asia ◽

South And Southeast Asia ◽

Net Flux ◽

The Difference ◽

Annual Flux

The net annual flux of carbon from south and southeast Asia as a result of changes in the area of forests was calculated for the period 1850 to 1985. The total net flux ranged from 14.4 to 24.0 Pg of carbon, depending on the estimates of biomass used in the calculations. High estimates of biomass, based on direct measurement of a few stands, and low estimates of biomass, based on volumes of merchantable wood surveyed over large areas, differ by a factor of almost 2. These and previous estimates of the release of carbon from terrestrial ecosystems to the atmosphere have been based on changes in the area of forests, or rates of deforestation. Recent studies have shown, however, that the loss of carbon from forests in tropical Asia is greater than would be expected on the basis of deforestation alone. This loss of carbon from within forests (degradation) also releases carbon to the atmosphere when the products removed from the forest burn or decay. Thus, degradation should be included in analyses of the net flux of carbon from terrestrial ecosystems. Degradation may also explain some of the difference between estimates of tropical forest biomass if the higher estimates are based on undisturbed forests and the lower estimates are more representative of the region. The implication of degradation for estimates of the release of carbon from terrestrial ecosystems is explored. When degradation was included in the analyses, the net flux of carbon between 1850 and 1985 was 30.2 Pg of carbon, about 25% above that calculated on the basis of deforestation alone (with high estimates of biomass), and about 110% above that calculated with low estimates of biomass. Thus, lower estimates of biomass for contemporary tropical forests do not necessarily result in lower estimates of flux.

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The role of structural iron(III) in the UV absorption by smectites

Clay Minerals ◽

10.1180/claymin.1979.014.2.01 ◽

1979 ◽

Vol 14 (2) ◽

pp. 93-102 ◽

Cited By ~ 24

Author(s):

Y. Chen ◽

D. Shaked ◽

A. Banin

Keyword(s):

Direct Evidence ◽

Uv Absorption ◽

Visible Light Absorption ◽

Absorption Intensity ◽

Dilute Suspensions ◽

Uv Visible ◽

Structural Iron ◽

Very High ◽

Uv Range

AbstractUV-visible light absorption spectra of dilute suspensions of standard and commercial montmorillonites (bentonites) and of nontronite, hectorite and pyrophyllite, were studied.All montmorillonites exhibit either an absorption band or a shoulder at a wavelength of 245 nm. The absorption peak for nontronite is shifted to 260 nm and absorption intensity is very high. Hectorite exhibits a very slight shoulder whereas pyrophyllite shows almost none. Absorption intensity in the UV range was found to be in direct correlation to structural octahedral Fe(III) contents. Direct evidence for the role of Fe(III) in the specific UV absorption of smectites was obtained by the fact that reduction with hydrazine fumes resulted in the disappearance of the peak and reoxidation with H2O2 caused its reappearance with even stronger intensity than originally. Mössbauer spectra showed that the Fe(III) disappeared almost completely in the reduced clay.

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Introducing Tropical Forests in Prehistory, History, and Modernity

Tropical Forests in Prehistory, History, and Modernity ◽

10.1093/oso/9780198818496.003.0005 ◽

2019 ◽

Author(s):

Patrick Roberts

Keyword(s):

Tropical Forest ◽

Tropical Forests ◽

Video Game ◽

Western World ◽

Human Relationships ◽

Urban Settlements ◽

Sir Walter Raleigh ◽

Human Foraging

Friedrich Wöhler was referring to the field of organic chemistry during the early 1800s when he wrote the above but his comments would not be out of place in the context of embarking upon a global study of past and present human relationships with tropical forests. Dense vegetation, difficulty of navigation, issues of preservation, political and health concerns, poisonous plants, animals, and insects, and the prospect of carrying out sampling or excavation in high humidity have all meant that our knowledge of human history and prehistory in these environments is under-developed relative to temperate, arid, or even polar habitats. There have been theoretical questions as to what kind of human activity one would even expect to find in tropical forest environments, which seem hostile to human foraging (Hart and Hart, 1986; Bailey et al., 1989) let alone thriving agricultural or urban settlements (Meggers, 1971, 1977, 1987). This has, until relatively recently, left the state of archaeological tropical forest research in a similar position to popular conceptions of these environments—untouched, primeval wilderness. Public ideas of an archaeologist investigating a tropical forest are probably synonymous with someone in a shabby-looking leather hat being chased, if not by a large stone boulder then by a group of Indigenous people with blowpipes, as they wade through dense undergrowth and vines while clutching a golden discovery that has been lost to the western world for thousands of years (Spielberg, 1981). The more recent development of the best-selling Uncharted video game series has done little to change these ideas amongst the next generation of media consumers, with players taking on the role of Francis Drake’s mythical ancestor in search of long lost treasure, frequently hidden within caves and ruins surrounded by vines and dense canopies (Naughty Dog et al., 2016). The idea of treasure hidden within tropical forest is also not a modern conception. The long-term myth of El Dorado, a city covered in gold, fuelled exploration of the tropical forests of South America by renowned individuals, including Sir Walter Raleigh, from the sixteenth to the nineteenth centuries (Nicholl, 1995).

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The role of phosphorus dynamics in tropical forests – a modeling study using CLM-CNP

Biogeosciences ◽

10.5194/bg-11-1667-2014 ◽

2014 ◽

Vol 11 (6) ◽

pp. 1667-1681 ◽

Cited By ~ 95

Author(s):

X. Yang ◽

P. E. Thornton ◽

D. M. Ricciuto ◽

W. M. Post

Keyword(s):

Tropical Forest ◽

Nutrient Limitation ◽

Tropical Forests ◽

Elevated Co2 ◽

Global Climate ◽

P Availability ◽

Tropical Ecosystems ◽

Model Simulations ◽

P Limitation

Abstract. Tropical forests play a significant role in the global carbon cycle and global climate. However, tropical carbon cycling and the feedbacks from tropical ecosystems to the climate system remain critical uncertainties in the current generation of carbon–climate models. One of the major uncertainties comes from the lack of representation of phosphorus (P), currently believed to be the most limiting nutrient in tropical regions. Here we introduce P dynamics and C–N–P interactions into the CLM4-CN (Community Land Model version 4 with prognostic Carbon and Nitrogen) model and investigate the role of P cycling in controlling the productivity of tropical ecosystems. The newly developed CLM-CNP model includes all major biological and geochemical processes controlling P availability in soils and the interactions between C, N, and P cycles. Model simulations at sites along a Hawaiian soil chronosequence indicate that the introduction of P limitation greatly improved the model performance at the P-limited site. The model is also able to capture the shift in nutrient limitation along this chronosequence (from N limited to P limited), as shown in the comparison of model-simulated plant responses to fertilization with the observed data. Model simulations at Amazonian forest sites show that CLM-CNP is capable of capturing the overall trend in NPP (net primary production) along the P availability gradient. This comparison also suggests a significant interaction between nutrient limitation and land use history. Model experiments under elevated atmospheric CO2 ([CO2]) conditions suggest that tropical forest responses to increasing [CO2] will interact strongly with changes in the P cycle. We highlight the importance of two feedback pathways (biochemical mineralization and desorption of secondary mineral P) that can significantly affect P availability and determine the extent of P limitation in tropical forests under elevated [CO2]. Field experiments with elevated CO2 are therefore needed to help quantify these important feedbacks. CO2 doubling model experiments show that tropical forest response to elevated [CO2] can only be predicted if the interactions between C cycle and nutrient dynamics are well understood and represented in models. Predictive modeling of C–nutrient interactions will have important implications for the prediction of future carbon uptake and storage in tropical ecosystems and global climate change.

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Direct Evidence for the Role of Inhibition in Resolving Interference

PsycEXTRA Dataset ◽

10.1037/e636632009-001 ◽

2009 ◽

Author(s):

M. Karl Healey ◽

Karen L. Campbell ◽

Lynn Hasher ◽

Lynn Ossher

Keyword(s):

Direct Evidence

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THE ROLE OF GRASSLAND IN MANAGEMENT

Proceedings of the New Zealand Grassland Association ◽

10.33584/jnzg.1968.30.1259 ◽

1968 ◽

pp. 44-49

Author(s):

B.K. Cameron

Keyword(s):

Soil Temperature ◽

Annual Rainfall ◽

Silt Loam ◽

Average Annual Rainfall ◽

Very High ◽

Wilting Point

THE PROPERTY to be discussed is a mixed sheep and cropping unit, situated ei ht a miles east of Ashburton and midway between the Ra aia and the Ashburton rivers. Average annual rainfall is 27 in., evenly spread, but there is very high summer evaporation and therefore frequent droughts. On average, the soil is below wilting point for 40 to 50 days each summer. Winters are cold with the soil temperature being below 48°F for about four months each year. The soil is a Lismore stony silt loam averaging 9 in. in depth over gravel.

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