Bioclimatic Models
Bioclimatic or niche models of individual species provide insight into possible range shifts due to climate change. Examples of this modeling approach include BIOCLIM, DOMAIN, generalized additive modeling GAM , generalized linear modeling GLM , artificial neural networks ANNs , genetic algorithms, genetic algorithm for rule-set prediction GARP , and several others Guisan and Thuiller, 2005 . Each of these techniques uses information about a species' present range and present climate to...
The South China Sea region
Sun et al. 2003 provide a near-continuous, high resolution i.e., 820-year average time interval between samples record from ODP Site 1144 20 3N, 117 25E taken from a water depth of 2,037 m equidistant from southern China, Taiwan, and the Philippines Figures 4.1 and 4.6 . The record covers marine isotope stages MIS 29 to 1 or the last 1.03 Myr. In terms of major ecological groups represented, there is little Figure 4.6. Relative abundance of major taxa and taxon groups in the pollen record from...
Abbreviations and acronyms
Anglo BRazilian Amazon Climate Observational Study Atmospheric General Circulation Model Atmospheric Model Inter-comparison Program CARbon Assimilation In the Biosphere Canadian Center for Climate Modelling and Analysis Center for Climate Systems Research National Institute for CLImate Long Range Investigation Mappings And CLIMate model of intermediate complexity Climate Prediction Center Merged Analysis of Precipitation Companhia de Pesquisa de Recursos Mineirais Brazilian National Center for...
CONCLUSION Mqv
International agreements have the right targets in place to take the first, most important steps towards protecting tropical forests from climate change. The Convention on Biological Diversity CBD has targeted a measurable reduction in global biodiversity loss by 2010, which implies completion of the global protected areas network, its adequate funding, and significant reduction of destructive practices outside of protected areas. The Kyoto Protocol of the UNFCCC is now in place, which sets a...
General Discussion And Conclusions
Perhaps the major feature of the Quaternary history of far eastern rainforest is that there has been little overall change in gross distribution over most of the area and through most of the period. Rainforest has shown tremendous resilience in the face of increasingly variable climatic conditions that have seen its partial replacement by more open vegetation types during drier and cooler glacial phases. The major spatial exception to this pattern is in tropical Australia, where the extensive...
Latitudinal and longitudinal gradients in Amazonian diversity
Even within the tropical forests of South America there are large gradients in plant species diversity Gentry, 1988, figs. 2a-c . For both tree alpha diversity and vascular plant gamma diversity, diversity has a broad peak between 1 N and 5 S. South of 5 S, tree alpha diversity decreases steeply and nearly linearly with latitude Figure 10.2b . Regional gamma diversity of all vascular plants peaks at 4 S and remains fairly constant from 5 S to 10 S, decreasing rapidly south of 14 S. To the...
Structural Changes
Among 59 plots monitored in old-growth Amazon forests with full tree-by-tree data, there has been a significant increase in above-ground biomass between the first and last time they were measured. Over approximately the last 20 years, the increase has been 0.61 0.22 tonnes of carbon per hectare per year, or a relative increase of 0.50 0.17 per year mean 95 confidence interval Baker et al., 2004a . Across all 59 plots, the above-ground biomass change is normally distributed and shifted to the...
Info Ivd
Figure 11.1. Relationships between soil organic matter content and exchangeable P in the 0-10-and 10-35-cm depths. Data are log-transformed and are from Silver et al. 1999 . a For the lowermontane wet forest r2 0.89, P lt 0.01 b for the montane wet forest r2 0.96, P lt 0.01 and c for the montane rain forest r2 0.82, P lt 0.01. tion and soil organic matter density could result in decreased P sorption due to organic matter coating of Fe and Al oxide minerals Lloyd et al., 2001 . At the landscape...
Climate change in low latitudes 1
The most pronounced climate change in low latitudes occurred in the Southeast Asian region, where climates change from seasonally dry monsoonal to everwet at about the Oligo-Miocene boundary, 23.6 Myr Morley et al., 2003 previously estimated at about 20 Myr in Morley 1998,2000a . This dramatic change is reflected both by pollen floras disappearance of Gramineae pollen, dramatic increase in pollen from peat swamps and the sudden appearance of coals in the lithological record. It is from the...
Uncertainties In Climate And Hydrology Variability Longterm Trends And Climate
As can be seen from the analysis of observed hydrometeorological fields in previous sections, no significant trends have been detected in the rainfall regime of the Amazon region as a whole, or on the discharge of the Amazon River and its tributaries, that could be attributed to deforestation and human-induced land-use changes, or to increase in the concentration of greenhouse gases. The detected contrasting rainfall trends in northern and southern Amazonia on decadal timescales are somewhat...
Interannual variability El Nino and tropical Atlantic impacts
Rainfall variability in various timescales in Amazonia has been the subject of several studies regarding physical causes that could include remote and local forcings. At seasonal and interannual timescales, remotely forced seasonal variations are usually linked to SST anomalies in the tropical Pacific and Atlantic Oceans. The Southern Oscillation SO and its extremes linked to anomalies in the tropical Pacific El Nino or La Nina at interannual scales , and to sea surface temperature SST...
Elevation
Except for its western and northern extremities, the Amazon Basin is marked in its flatness 85 of the Amazon Basin, including its Andean headwaters, are under 500 m in elevation. Ninety-seven percent of rainforests lie below 500 m S. Saatchi, pers. commun. . The main stem of the Amazon drops only 215 m from where the Maranon passes the final Andean foothill at the Pongo de Manseriche to its mouth 3,200 km away at Ilha de Marajo Figure 10.1b . To the north and south of the Maranon, alluvial fans...
Diversity in relation to precipitation and geology
In the current analysis, alpha diversity shows broad correlations with both precipitation patterns and geology Figure 10.5a-d, see color section . Total precipitation amount is positively correlated with diversity Figure 10.5a and average length of dry season negatively correlated Figure 10.5d . Both reproduce the basic pattern of high average diversity in central and western Amazonia, and along the main stem of the Amazon, though with notable discrepancies. Strong gradients in alpha diversity...
Precipitation and diversity
Diversity is clearly correlated with climatic stability, and the plateau in Amazonian diversity from 1 N to 5 S falls squarely on the area with no predictable dry season, and the lowest variability in climate over time Figures 10.5b, c . Both local and regional diversity in all data sets analyzed showed this trend. Diversity may also appear anomalously low in areas with a shorter dry season as calculated through the number of months that average below 100 mm, especially if the timing of...
Altitudinal Variations
On tropical mountains, there are marked altitudinal changes of vegetation Troll, 1959 . The concept of an actual zonation is rather too strict to be useful, but there is no doubt that as one ascends a mountain there are gradual changes. Most tree species have an ecological amplitude in terms of mean annual temperature MAT , of about 6 C van Steenis, 1934-36 . There are some conspicuous exceptions to this, but it applies to many species. There is thus a continuum of change seen as the climber...
The middomain effect
The idea that simple geometry explains many patterns of diversity Colwell and Lees, 2000 has been advanced for taxa as disparate as small mammals McCain, 2004 , corals Connolly et al., 2003 , and Andean epiphytes Kessler, 2001 . However, this study found no evidence for the mid-domain effect in Amazonian or Andean flora. Ter Steege et al. 2003 also suggested that the mid-domain effect was responsible for the peak in Amazonian diversity south of the equator. Results from the current study show...
Contributors
Earth and Biosphere Institute, Geography, University of Leeds, Leeds LS2 9JT, U.K. and Max-Planck-Institut fur Biogeochemie, Postfach 100164, 07701 Jena, Germany Email geotrb leeds.ac.uk Met Office, Hadley Centre for Climate Prediction and Research, Fitzroy Road, Exeter EX1 3PB, U.K. Email richard.betts metoffice.com Raymonde Bonnefille Cerege, CNRS, Route Leon Lachamp, BP 80, 13545 Aix-en-Provence, Cedex 04 France. Email rbonnefi cerege.fr Department of Biological Sciences, Florida Institute...
Figures
1.1 Ice-age distributions of closed canopy megathermal rainforests 3 1.2 Stratigraphie range of angiosperm and pteridophyte megathermal species, or species pairs, which can be identified on the basis of pollen and spores 4 1.3 Numbers of stratigraphically useful angiosperm pollen types per epoch 7 1.4 Closed canopy megathermal rainforests first became widespread during the 8 1.5 Generalized oxygen isotope curve for benthonic bottom dwelling foraminifera through the 9 1.6 Distribution of closed...
The Periodicity Of Change
For substantial periods western Amazonian and southern Andean sites do appear to have similar histories. Sedimentary records in the Colombian Andes, the Bolivian 0 50 100 150 200 250 300 350 400 0 50 100 150 200 250 300 350 400 0 50 100 150 200 250 300 350 400 0 50 100 150 200 250 300 350 400 Figure 3.2. C02 concentrations from the Vostok core Petit et al., 1999 upper line and the relative rate of change in C02 concentrations between samples lower line . Andes, the Chilean pampas, and the...
The early evidence for human occupation
As elsewhere, there are formidable holes in the archeological records relating to initial human entrance into the now-humid Neotropics, and new evidence tends to accumulate slowly because early human groups were small and often highly mobile, leaving behind few tangible remains. Nonetheless, we know considerably more about the subject now than we did 10 to 15 years ago. There is convincing evidence of human occupation dating to the Late and terminal Pleistocene periods between c. 15.2 kcal. yr...
Nonforest Herbs
Figure 4.3. Representation of major pollen taxa in relation to vegetation along an altitudinal surface sample transect in Papua-New Guinea modified from Flenley, 1973 . Figure 4.4. Relative abundance of major pollen groups, taxa, and charcoal derived from core-top samples in the northwestern Australian-southern Indonesian region based on a pollen sum of total dryland pollen excluding pteridophytes. Data from van der Kaars and De Deckker 2003 and van der Kaars 2001 . Figure 4.4. Relative...
Geology and diversity
The current study shows that, for South American tropical forests, tree alpha diversity is also associated with geological age of substrate. While subsidiary to rainfall effects, alpha diversity tended to be higher on younger substrates, which in turn were more fertile substrates, even after accounting for precipitation variability Figure 10.5d . This is almost certainly not an effect of age per se, but rather due to the correlation between age and fertility in Amazonian surface geology. This...
REFERENCES Txn
Arford, M. R. and Horn, S. P. 2004 Pollen evidence of the earliest maize agriculture in Costa Rica. Journal of Latin American Geography 3, 108-115. Athens, J. S. and Ward, J. V. 1999 The Late Quaternary of the western Amazon Climate, vegetation, and humans. Antiquity 73, 287-302. Bailey, R. C., Head, G., Jenike, M., Owen, B., Rechtman, R., and Zechenter, E. 1989 Hunting and gathering in tropical rain forest Is it possible American Anthropologist 91, 59-82. Bartlett, A. S. and Barghoorn, E. S....
INTRODUCTION Pkh
In Africa the lowland rain forest occurs under significantly drier conditions than in other continents, within an average precipitation of 1,600 to 2,000 mm yr, although higher rainfall is observed around the Atlantic coast of Cameroon, Gabon, and in the Central Zaire Basin. Seasonal distribution of precipitation is far from being uniform White, 1983 . Variations in the duration of the dry season follow distance from the equator in both hemispheres and also along a west-to-east gradient. The...
Precipitation
The Amazon River discharges roughly 20 of Earth's river water that reaches the ocean, even though its basin occupies just 2 of continental land area. The spectacular discharge rate is due to the deep convection that forms over the Amazon Basin, the moisture brought in from the Atlantic by easterly winds, and the huge amounts of orographic rainfall generated as water vapor from the Atlantic is forced upwards by the Andean massif. While the mean annual rainfall is 2,400 mm yr-1, precipitation is...
Deglaciation
The timing and rate of Andean deglaciation is somewhat contentious, as it has been suggested that the southern Andes mirrors the Vostok record from Antarctica, while the northern Andes mirrors the GISP record from Greenland Seltzer et al., 2002 . It appears that the more southern tropical Andes entered a deglacial phase between 21 kcal. yr bp and 19 kcal. yr bp within the classic LGM of the northern hemisphere , while the northern Andes may not have warmed until c. 16 kcal. yr bp. This...
Bp J
11,000 - 8600 BP-S600 - 7000 BP -7000 - 5-000 BP -5000 - 3000 BP -3000 - 500 BP -350 BP- DECIDUOUS FOREST SEMi-EVERGREEN EVERGREEN EVERGREEN OLD CLEARING Figure 7.2. The frequencies of early successional phytoliths and burnt successional and arboreal phytoliths in modern tropical forests and through time at Lake La Yeguada. The data profiles from the Late Pleistocene period at El Valle, where human disturbance was not detected, are also displayed for comparison. At c. 12.9 kcal. yr bp at La...
Changes in the hydrology of the Amazon River Basin
Macroscale hydrological models, which model the land-surface hydrological dynamics of continental-scale river basins, have rapidly developed during the last decade Russell and Miller, 1990 Marengo et al., 1994 Miller et al., 1994 Nijssen et al., 1997, 2001 . These models can act as links between global climate models and water resource systems on large spatial scales and long-term timescales. Predictions of river discharge in the Amazon Basin for present climates and 2 x CO2 future scenarios...
Precipitation patterns
Patterns of precipitation amount and variability in Amazonia change with both latitude and longitude. Analysis of TRMM data shows average annual precipitation in the Amazonian lowlands peaks at 2-4 S latitude, with a broad plateau from 4 N to 4 S of the equator. Precipitation decreases steadily to the south and north Figure 10.3e . Precipitation at low latitudes can be either high or low, while sites to the north and south have more uniformly low rainfall. Precipitation variability, measured as...
Trends In Rainforest Diversity Based On The Palynological Record
Obtaining meaningful data regarding palynomorph diversity, which can be interpreted in terms of species diversity of vegetation, is fraught with difficulties, and so is rarely attempted Birks and Line, 1990 . Differences in depositional environment, as well as taphonomic factors, have a significant effect on such estimates, making number of pollen types, or pollen diversity indices difficult to interpret. Also, individual analysts may have different concepts of what constitutes a pollen type...
Differences Between Quaternary And Tertiary Megathermal Forests
Using Quaternary analogs to interpret ecological and climatic successions from the Tertiary raises two main issues 1 was there a fundamental difference between Quaternary and Tertiary rainforests and 2 were Tertiary species compositions so different from the Quaternary as to make comparison fruitless With respect to the first of these issues, it is now clear that there was one major difference between Quaternary rainforests, and those from the Miocene and Early Pliocene. Over the last 2.8 Myr,...
M B Bush W D Gosling and P A Colinvaux INTRODUCTION
Data from palynology, taxonomy and isotopic analyses, allied to climate models, reveal the complexity of the history of Amazon ecosystems. Evidence from these records suggests that Pleistocene climatic change was neither uniform nor synchronous across the basin, but that its effects were pervasive. A major obstacle to Amazon paleoecology is paucity of lakes containing uninterrupted sedimentary sequences spanning one or more glacial cycles. To date, the only fossil pollen records from lowland...
REFERENCES Psv
Behling, H. and Hooghiemstra, H. 2000 Holocene Amazon rain forest-savanna dynamics and climatic implications High-resolution pollen record from Laguna Loma Linda in eastern Colombia. Journal of Quaternary Science 15, 687-695. Bond, W. J. G., Woodward, F. I., and Midgley, G. F. 2004 The global distribution of ecosystems in a world without fire. New Phytologist 165, 525-538. Boom, A., Marchant, R. A., and Hooghiemstra, H. 2002 Pollen-based biome and S13C reconstructions for the past 450,000,...
Subject index
measuring C4 and C3 abundance, 339 8180 data, 64 Huascaran ice core, 44 Climate Observational Study edaphic and secondary grassland Africa , 121 adiabatic lapse rate, see lapse rates aerosol, 250, 252 African rainforest, see Guineo-Congolian rainforest Afromontane evergreen forests, 121-122 Amazon Basin agricultural pressure, 211 Amazon Basin crop origins, 203 cultivation of crops, Holocene, 201-206 domesticated crops, Holocene, 201-206 Central America, 204-205 South America, 203-205 during the...
ECOLOGICAL RESPONSES TO PLEISTOCENE CLIMATE CHANGE Expansion of C grasslands
The distribution of modern day C3 and C4 plants is primarily governed by temperature, but may be modified by changes in atmospheric C02 Ehleringer et al., 1991, 1997 Sage et al., 1999 . C4 plants, with their intrinsically higher WUE, have a strong competitive advantage in hot and arid regions, but the associated energetic costs of the C4-syndrome i.e., C02-pump renders them less competitive in regions experiencing moderate to low temperatures. The point at which C4 plant abundance drops below...
Conclusion
It is specifically the interaction of low atmospheric C02 and global cooling and aridity that is critical for understanding the potential response of plants to changes in Pleistocene climate. The combination of modeling and palynological data should put to rest the notion that lowland tropical forests were severely restricted in glacial times by expanding C4-dominated grasslands. Rather, evidence indicates that seasonal forest likely encroached on rainforest in lowland regions and that...
Decomposition
Actual evapotranspiration is one of the strongest predictors of decomposition on a global scale Aerts, 1997 , although its explanatory power is quite weak r2 0.14 . Regionally, the relationship between rainfall and decomposition appears even weaker. Using elevation gradient studies within tropical forests, Silver 1998 found no predictive relationship between rainfall and decomposition rates. A 50 reduction in precipitation reaching the forest floor had no effect on litter decomposition rates in...
Major trends and patterns of prehistoric tropical forest modification
Very significant to more moderate human impacts can be identified on the full spectrum of tropical forest vegetation evergreen, semi-evergreen, and deciduous formations from Mexico to the Amazon Basin Figures 7.4 and 7.5 . Often, especially in the highly seasonal forests of Central America, the impacts were intense, and a significant number of arboreal taxa were reduced to low levels by agricultural activity. From a large swamp called El Venancio, located in Guerrero, Mexico very close to the...
a 1
Figure 5.3. Modern pollen rain from the drier semi-evergreen forest in Cameroon, Kandara site a location map of the studied transect samples 1 to 26 b comparison between arboreal pollen and leaf area index Cournac et al., 2002 . After Bremond et al., 2005 and Vincens et al., 2000. Figure 5.3. c Simplified pollen diagram after Yincens et al., 2000 calculated versus pollen sum including all identified taxa, Cyperaceae, and spores . Denotes names representing the greatest probability for...
Rainfall distribution and seasonal rainfall and river seasonal variability
The Amazon River drains an area of 6.2 x 106 km2 and discharges an average of 6,300 km3 of water to the Atlantic Ocean annually. The annual cycle of rainfall in the region has been extensively described in Rao and Hada 1990 , Marengo 1992 , Figueroa and Nobre 1999 , Marengo and Nobre 2001 , Liebmann and Marengo 2001 , Marengo 2004b . The spatial distribution of rainfall shows three centers of abundant precipitation in the Amazon Basin. One is located in northwest Amazonia, with more than 3,600...
Detected and projected changes in precipitation
The IPCC Third Assessment Report IPPC, 2001 has shown no clear signs of negative trends in Amazonia due to increased deforestation as one would expect Section 9.2.3 . Section 9.2.5 describes trends and long-term variability in observed mean seasonal and annual rainfall and discharges. The magnitude and size of the trends depend on rainfall data sets, length of records, etc. and the uncertainty is high since Figure 9.7. Air temperatures in the Amazon region as simulated by five IPCC models R30...
Biosphere Modeling
Vegetation is a major factor affecting land surface processes Figure 6.3 , and a good measure of ambient climate and change in this. Therefore, a central part of understanding climate change impact is to understand the correspondence between climate and the distribution of vegetation, both in terms of major vegetation formations, or biomes, and individual plants or species. Modeling the biosphere is not a new field of research. Initial attempts were carried out by Kostitzin 1935 . Working on...
Phylogenies
The empirical paleoenvironmental data discussed above have provided an improved understanding of the response of the vegetation in the Amazon Basin to known global climate change. New phylogenetic studies question some long-held assumptions about the nature and pace of Amazonian speciation and offer some critical insights into when speciation occurred. Examples of biological insights arising from phylogenies come from a variety of organisms. Heliconius butterflies Brown, 1987 , frogs, and...
Scenario For Rainforest Evolution And Diversification
The evolution and diversification of megathermal rainforests has been dependent on, and proceeded parallel with, a succession of geological and climatic and dispersal events, controlled largely by plate-tectonic and astronomical processes, in parallel with evolutionary pressures for plants to reproduce and colonize all available land space. These events have occurred in a unique time sequence. The result is that today each geographically separated rainforest area contains its own association of...
References
Abreu, V. S. and Anderson, J. B. 1998 Glacial eustacy during the Cenozoic Sequence stratigraphic implications. AAPG Bulletin 82, 1385-1400. Anderson, J. A. R. and Muller, J. 1975 Palynological study of a Holocene peat and a Miocene coal deposit from N.W. Borneo. Review of Palaeobotany and Palynology 19, 291-351. Ashton, P., Givnish, T. and Appanah, S. 1988 Staggered flowering in the Dipterocarpaceae New insights into floral induction and the evolution of mast fruiting in the aseasonal tropics....
Atmospheric and hydrological water balance
The hydrological cycle of the Amazon region is of great importance since the region plays an important role in the functioning of regional and global climate. Variations in its regional water and energy balances at year-to-year and longer timescales are of Figure 9.3. Seasonal cycle of river discharges and levels in northern and southern Amazonia. Levels are in cm Rio Negro at Manaus . Discharges from the Amazon, Madeiras, and Tocantins Rivers are in 103 m3 s_1. Source M. Costa and M. Coe....
Species diversity and environmental gradients
To look at the influence of these environmental gradients on species diversity, we looked at alpha and gamma diversity in Amazonia Whittaker, 1972 . Alpha diversity was measured as both species density Nha1 and also Fisher's alpha Fisher et al., 1943 . Fisher's alpha has been used extensively in comparisons of Neotropical forest diversity as it is relatively independent of plot size Condit et al., 1996 Leigh, 1999 Ter Steege et al., 2003 . Gamma diversity was estimated as the total number of...
Litter Inputs
Alterations to the amount and timing of rainfall in tropical forests may significantly affect nutrient-cycling via litter production, although the relationship between climate Anthropogenic Increased Nitrogen Deposition Precipitation NH4 Anions NO3- Cations Leaching losses increase Figure 11.4. The potential effects of anthropogenic nitrogen deposition and increased precipitation in tropical forests. Increased inputs of ammonium could stimulate ammonium-leaching in variable charge soils, and...
Introduction
The history of megathermal currently tropical rainforests over the last 30kyr is now becoming relatively well-understood, as demonstrated by the many contributions in this volume. However, our perception of their longer-term history remains highly fragmentary. There is a real need for a better understanding of rainforest history on an evolutionary timescale, not only to have a better idea of the biological, geological, and climatic factors which have led to the development of the most diverse...
Biome modeling
A continental-scale study the VEMAP project VEMAP members, 1995 demon-strated the interdependence of biogeographical and biogeochemical aspects of the ecological response to climate change assessing how global change will affect ecosystems and must therefore include both aspects. Such a combined approach is exemplified by the process-based equilibrium terrestrial biosphere model BIOME-3 that simulates vegetation distribution and biogeochemistry Haxeltine and Prentice, 1996 . BIOME-3 predicts...