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Regional Studies

CLIMATE CHANGE AND SPECIES / ECOSYSTEMS - ABSTRACTS

Global Studies

Root, T.L., J.T. Price, K.R. Hall, S.H. Schneider, C. Rosenzweig, and J.A. Pounds. 2003. "Fingerprints of global warming on wild animals and plants," Nature, Vol. 421, 57-60.
PDF: http://www.giss.nasa.gov/gpol/docs/2003/2003_RootPrice.pdf
ABSTRACT: Over the past 100 years, the global average temperature has increased by approximately 0.6°C and is projected to continue to rise at a rapid rate. Although species have responded to climatic changes throughout their evolutionary history, a primary concern for wild species and their ecosystems is this rapid rate of change. We gathered information on species and global warming from 143 studies for our meta-analyses. These analyses reveal a consistent temperature-related shift, or 'fingerprint', in species ranging from molluscs to mammals and from grasses to trees. Indeed, more than 80% of the species that show changes are shifting in the direction expected on the basis of known physiological constraints of species. Consequently, the balance of evidence from these studies strongly suggests that a significant impact of global warming is already discernible in animal and plant populations. The synergism of rapid temperature rise and other stresses, in particular habitat destruction, could easily disrupt the connectedness among species and lead to a reformulation of species communities, reflecting differential changes in species, and to numerous extirpations and possibly extinctions.

Parmesan, Camille and Gary Yohe. 2003. "A globally coherent fingerprint of climate change impacts across natural systems," Nature, Vol. 421, 02 January, pp. 37-42.
ABSTRACT: Causal attribution of recent biological trends to climate change is complicated because non-climatic influences dominate local, short-term biological changes. Any underlying signal from climate change is likely to be revealed by analyses that seek systematic trends across diverse species and geographic regions; however, debates within the Intergovernmental Panel on Climate Change (IPCC) reveal several definitions of a 'systematic trend'. Here, we explore these differences, apply diverse analyses to more than 1,700 species, and show that recent biological trends match climate change predictions. Global meta-analyses documented significant range shifts averaging 6.1 km per decade towards the poles (or metres per decade upward), and significant mean advancement of spring events by 2.3 days per decade. We define a diagnostic fingerprint of temporal and spatial 'sign-switching' responses uniquely predicted by twentieth century climate trends. Among appropriate long-term/large-scale/multi-species data sets, this diagnostic fingerprint was found for 279 species. This suite of analyses generates 'very high confidence' (as laid down by the IPCC) that climate change is already affecting living systems.

Bergengren, Jon C., Starley L. Thompson, David Pollard, and Robert M. DeConto. 2001. "Modeling Global Climate-Vegetation Interactions in a Doubled CO2 World," Climatic Change, Vol. 50, No. 1-2, July, pp. 31-75.
ABSTRACT: A coupled global vegetation-climate model is used to investigate the effects of vegetation feedbacks on climate change due to doubling atmospheric CO2. The Equilibrium Vegetation Ecology model (EVE) simulates global terrestrial vegetation and is designed for interactive coupling with climate models. Terrestrial vegetation is resolved into 110 plant life forms, which represent groups of species with similar physiognomic characteristics and migrational responses to climate change, thus preserving the spatial integrity of each life-form distribution as climate changes. EVE generates a quantitative description of plant community structure defined by total vegetation cover and the fractional covers of life forms as a function of climate. The equilibrium distribution of each life form is predicted from monthly mean temperature, precipitation, and relative humidity, based on observed correlations with the present climate. The fractional covers of the life forms at each site are determined by parameterizations of dynamic ecological processes: competition for sunlight, disturbances by fire and treefall. A second model (LEAF) simulates the seasonal phenology of EVE's plant canopies, driven by the daily climate at each location, and provides the physical quantities needed for coupling vegetation and climate models. Two pairs of coupled EVE-GCM simulations are described, both with 1× and 2×CO2: the first with prescribed fixed vegetation, and the other with fully interactive vegetation. Large effects of vegetation feedbacks in the interactive simulations are found at the northern and southern ecotones of the boreal forest. Poleward migration of boreal forests into tundra caused by warming due to elevated CO2 is enhanced by a strong snow-masking albedo feedback, consistent with earlier studies. The invasion of temperate grasslands into the southern boreal forest is also enhanced due to summer warming spreading from the north, despite the opposing sense of the grassland-forest albedo feedback. Desertification of subtropical grasslands is mostly reversed in the interactive simulations due to enhanced monsoonal precipitation. These interactions and other climate and plant community changes caused by climate-vegetation feedbacks are discussed on a regional basis.

Guisan, Antoine and Jean-Paul Theurillat. 2000. "Assessing alpine plant vulnerability to climate change: a modeling perspective," Integrated Assessment, Vol. 1, pp. 307-320.
ABSTRACT: The potential ecological impact of ongoing climate change has been much discussed. High mountain ecosystems were identified early on as potentially very sensitive areas. Scenarios of upward species movement and vegetation shift are commonly discussed in the literature. Mountains being characteristically conic in shape, impact scenarios usually assume that a smaller surface area will be available as species move up. However, as the frequency distribution of additional physiographic factors (e.g., slope angle) changes with increasing elevation (e.g., with few gentle slopes available at higher elevation), species migrating upslope may encounter increasingly unsuitable conditions. As a result, many species could suffer severe reduction of their habitat surface, which could in turn affect patterns of biodiversity. In this paper, results from static plant distribution modeling are used to derive climate change impact scenarios in a high mountain environment. Models are adjusted with presence/absence of species. Environmental predictors used are: annual mean air temperature, slope, indices of topographic position, geology, rock cover, modeled permafrost and several indices of solar radiation and snow cover duration. Potential Habitat Distribution maps were drawn for 62 higher plant species, from which three separate climate change impact scenarios were derived. These scenarios show a great range of response, depending on the species and the degree of warming. Alpine species would be at greatest risk of local extinction, whereas species with a large elevation range would run the lowest risk. Limitations of the models and scenarios are further discussed.

Sykes, Martin T., I. Colin Prentice, and Fouzia Laarif. 1999. "Quantifying the Impact of Global Climate Change on Potential Natural Vegetation," Climatic Change, Vol. 41, No. 1, January, pp. 37-52.
ABSTRACT: Impacts of climate change on vegetation are often summarized in biome maps, representing the potential natural vegetation class for each cell of a grid under current and changed climate. The amount of change between two biome maps is usually measured by the fraction of cells that change class, or by the kappa statistic. Neither measure takes account of varying structural and floristic dissimilarity among biomes. An attribute-based measure of dissimilarity (?V) between vegetation classes is therefore introduced. ?V is based on (a) the relative importance of different plant life forms (e.g. tree, grass) in each class, and (b) a series of attributes (e.g. evergreen-deciduous, tropical-nontropical) of each life form with a weight for each attribute. ?V is implemented here for the most used biome model, BIOME 1 (Prentice, I. C. et al., 1992). Multidimensional scaling of pairwise ?V values verifies that the suggested importance values and attribute weights lead to a reasonable pattern of dissimilarities among biomes. Dissimilarity between two maps (?V) is obtained by area-weighted averaging of ?V over the model grid. Using ?V, present global biome distribution from climatology is compared with anomaly-based scenarios for a doubling of atmospheric CO2 concentration (2 × CO2), and for extreme glacial and interglacial conditions. All scenarios are obtained from equilibrium simulations with an atmospheric general circulation model coupled to a mixed-layer ocean model. The 2 × CO2 simulations are the widely used OSU and GFDL runs from the 1980's, representing models with low and high climate sensitivity, respectively. The palaeoclimate simulations were made with CCM1, with sensitivity similar to GFDL. ?V values for the comparisons of 2 × CO2 with present climate are similar to values for the comparisons of the last interglacial and mid-Holocene with present climate. However, the two simulated 2 × CO2 cases are much more like each other than they are to the simulated interglacial cases. The largest ?V values were between the last glacial maximum and all other cases, including the present. These examples illustrate the potential of ?V in comparing the impacts of different climate change scenarios, and the possibility of calibrating climate change impacts against a palaeoclimatic benchmark.

Donnelly, Maureen A., and Martha L. Crump. 1998. "Potential Effects of Climate Change on Two Neotropical Amphibian Assemblages," Climatic Change, Vol. 39, No. 2-3, July, pp. 541-561.
ABSTRACT: Although anuran amphibians are diverse and conspicuous in many vertebrate communities, worldwide population declines have been observed. Climatic change is a global factor that has been implicated in some of these declines. In this paper, we speculate on how Neotropical anurans might respond to changes in climate predicted by Hulme and Viner (1998). We focus on two distinct groups of Neotropical anurans: frogs that live and oviposit in leaf litter and frogs that congregate at ponds to breed. Increased temperature, increased length of dry season, decreased soil moisture, and increased inter-annual rainfall variability will affect Neotropical frogs strongly. We expect that these changes will directly affect frogs by changing reproductive success and breeding periodicity, and indirectly by altering the invertebrate prey base. The individual effects will likely translate into changes at the population and community levels. We also speculate on how climatic change will affect Neotropical amphibians that are restricted ecologically and/or geographically. We suggest directions for future research that will increase our ability to predict how amphibians in the New World tropics will respond to climatic change.

Kirilenko, Andrei P. and Allen M. Solomon. 1998. "Modeling Dynamic Vegetation Response to Rapid Climate Change Using Bioclimatic Classification," Climatic Change, Vol. 38, No. 1, January, pp. 15-49.
ABSTRACT: Modeling potential global redistribution of terrestrial vegetation frequently is based on bioclimatic classifications which relate static regional vegetation zones (biomes) to a set of static climate parameters. The equilibrium character of the relationships limits our confidence in their application to scenarios of rapidly changing climate. Such assessments could be improved if vegetation migration and succession would be incorporated as response variables in model simulations. We developed the model MOVE (Migration Of VEgetation), to simulate the geographical implications of different rates of plant extirpation and in-migration. We used the model to study the potential impact on terrestrial carbon stocks of climate shifts hypothesized from a doubling of atmospheric greenhouse gas concentration. The model indicates that the terrestrial vegetation and soil could release carbon; the amount of this carbon pulse depends on the rate of migration relative to the rate of climate change. New temperate and boreal biomes, not found on the landscape today, increase rapidly in area during the first 100 years of simulated response to climate change. Their presence for several centuries and their gradual disappearance after the climate ceases to change adds uncertainty in calculating future terrestrial carbon fluxes.

Forests Species/Ecosystems

Chen, Xiongwen, "Modeling the Effects of Global Climatic Change at the Ecotone of Boreal Larch Forest and Temperate Forest in Northeast China," Climatic Change, Vol. 55, No. 1-2, October, pp. 77-97.
ABSTRACT: The dynamics of the forest at the ecotone of the boreal forest and temperate forest in Northeast China were simulated using the adapted gap model BKPF under global climatic change (GFDL scenario) and doubled CO2 concentrations at 50 years in the future. The response of tree species and species with similar biological characteristics under global climate change and double CO2 concentrations were based on biophysical limits of the tree species in the area and their biological competition. The results showed that after 50 years the stand density and LAI (leaf area index) of the forest growing from a clear-cut would not be significantly different from those under current conditions. Stand productivity would increase about 7%, and stand aboveground biomass would increase 15%. However, the stand density of the current mature forest would be reduced by more than 20%. The stand would be dominated by Quercus mongolica Fisch., Populus davidiana Dode., Betula spp. and other broadleaved tree species, and Quercus mongolica would account for about 50% of the total density. The stand biomass would be reduced by more than 90%. Quercus mongolica would comprise about 57% of the total stand biomass. The stand productivity would not change significantly, but it would be comprised mainly of Quercus mongolica, Populus davidiana, Betula spp. The current stand height would decrease slightly. The stand LAI would decline dramatically, moreover, Quercus mongolica would comprise about 50% of the stand LAI.

Perez-Garcia, John, Linda A. Joyce, A. David Mcguire, and Xiangming Xiao. 2002. "Impacts of Climate Change on the Global Forest Sector," Climatic Change, Vol. 54, No. 4, September, pp. 439-461.
ABSTRACT: The path and magnitude of future anthropogenic emissions of carbon dioxide will likely influence changes in climate that may impact the global forest sector. These responses in the global forest sector may have implications for international efforts to stabilize the atmospheric concentration of carbon dioxide. This study takes a step toward including the role of global forest sector in integrated assessments of the global carbon cycle by linking global models of climate dynamics, ecosystem processes and forest economics to assess the potential responses of the global forest sector to different levels of greenhouse gas emissions. We utilize three climate scenarios and two economic scenarios to represent a range of greenhouse gas emissions and economic behavior. At the end of the analysis period (2040), the potential responses in regional forest growing stock simulated by the global ecosystem model range from decreases and increases for the low emissions climate scenario to increases in all regions for the high emissions climate scenario. The changes in vegetation are used to adjust timber supply in the softwood and hardwood sectors of the economic model. In general, the global changes in welfare are positive, but small across all scenarios. At the regional level, the changes in welfare can be large and either negative or positive. Markets and trade in forest products play important roles in whether a region realizes any gains associated with climate change. In general, regions with the lowest wood fiber production cost are able to expand harvests. Trade in forest products leads to lower prices elsewhere. The low-cost regions expand market shares and force higher-cost regions to decrease their harvests. Trade produces different economic gains and losses across the globe even though, globally, economic welfare increases. The results of this study indicate that assumptions within alternative climate scenarios and about trade in forest products are important factors that strongly influence the effects of climate change on the global forest sector.

Morgan, M. Granger, Louis F. Pitelka, and Elena Shevliakova. 2001. "Elicitation of Expert Judgments of Climate Change Impacts on Forest Ecosystems," Climatic Change, Vol. 49, No. 3, May, pp. 279-307.
ABSTRACT: Detailed interviews were conducted with 11 leading ecologists to obtain individual qualitative and quantitative estimates of the likely impact of a 2 × [CO2] climate change on minimally disturbed forest ecosystems. Results display a much richer diversity of opinion than is apparent in qualitative consensus summaries, such as those of the IPCC. Experts attach different relative importance to key factors and processes such as soil nutrients, fire, CO2 fertilization, competition, and plant-pest-predator interactions. Assumptions and uncertainties about future fire regimes are particularly crucial. Despite these differences, most of the experts believe that standing biomass in minimally disturbed Northern forests would increase and soil carbon would decrease. There is less agreement about impacts on carbon storage in tropical forests. Estimates of migration rates in northern forests displayed a range of more than four orders of magnitude. Estimates of extinction rates and dynamic response show significant variation between experts. A series of questions about research needs found consensus on the importance of expanding observational and experimental work on ecosystem processes and of expanding regional and larger-scale observational, monitoring and modeling studies. Results of the type reported here can be helpful in performing sensitivity analysis in integrated assessment models, as the basis for focused discussions of the state of current understanding and research needs, and, if repeated over time, as a quantitative measure of progress in this and other fields of global change research.

Herbst, Mathias and Georg Hörmann. 1998. "Predicting Effects of Temperature Increase on the Water Balance of Beech Forest - An Application of the 'KAUSHA' Model," Climatic Change, Vol. 40, No. 3-4, December, pp. 683-698.
ABSTRACT: The water balance model 'KAUSHA' (Halldin, 1989) was applied to a 100-year-old beech (Fagus sylvatica L.) forest in northern Germany. Overall, a satisfying agreement between modelled evapotranspiration values and independent micrometeorological measurements (Bowen ratio energy balance method) could be observed, although for rainy days KAUSHA showed a tendency to overestimate evapotranspiration. The model was used to predict the effects of a climate warming on the water budgets of the forest. It is shown that a temperature increase of 2°C due to a rising CO2 content of the atmosphere will not change the yearly totals of evapotranspiration significantly, but could have serious effects on the soil water balance during the vegetation period. Because under climate change conditions a higher amount of the available soil water has already been evaporated in winter and spring, soil water content will limit the transpiration of the trees from July to September much more strongly. Therefore, the yield of beech forest might also suffer from drought effects. It can be concluded that a better knowledge of the seasonal distribution of rainfall under climate change conditions is indispensable for predicting effects of rising temperatures and CO2 concentrations on ecosystems.

Ramakrishnan, P. S. 1998. "Sustainable Development, Climate Change and Tropical Rain Forest Landscape," Climatic Change, Vol. 39, No. 2-3, July, pp. 583-600.
ABSTRACT: A potential impact of climate change in the south Asian context in general and the Indian subcontinent in particular is an increase in rainfall, in some areas up to 50%. Using an extensive information base available on the dynamics of landscape structure and function of the northeastern hill areas of India, scenarios on landscape changes, as an adaptation to climate change, have been constructed. Climate change would impose a variety of stresses on sustainable livelihood of the inhabitants of the rain-forested areas through stresses on ecosystem function. It is concluded that appropriate management strategies for natural forests and plantation forestry should go hand in hand with a comprehensive rural ecosystem rehabilitation plan.

Ravindranath, N.H., and R. Sukumar. 1998. "Climate Change and Tropical Forests in India," Climatic Change, Vol. 39, No. 2-3, July, pp. 563-581.
ABSTRACT: India has 64 Mha under forests, of which 72% are tropical moist deciduous, dry deciduous, and wet evergreen forest. Projected changes in temperature, rainfall, and soil moisture are considered at regional level for India under two scenarios, the first involving greenhouse gas forcing, and the second, sulphate aerosols. Under the former model, a general increase in temperature and rainfall in all regions is indicated. This could potentially result in increased productivity, and shift forest type boundaries along attitudinal and rainfall gradients, with species migrating from lower to higher elevations and the drier forest types being transformed to moister types. The aerosol model, however, indicates a more modest increase in temperature and a decrease in precipitation in central and northern India, which would considerably stress the forests in these regions.
Although India seems to have stabilized the area under forest since 1980, anthropogenic stresses such as livestock pressure, biomass demand for fuelwood and timber, and the fragmented nature of forests will all affect forest response to changing climate. Thus, forest area is unlikely to expand even if climatically suitable, and will probably decrease in parts of northeast India due to extensive shifting cultivation and deforestation. A number of general adaptation measures to climate change are listed.

Benzing, David H. 1998. "Vulnerabilities of Tropical Forests to Climate Change: The Significance of Resident Epiphytes," Climatic Change, Vol. 39, No. 2-3, July, pp. 519-540.
ABSTRACT: Predictions about the impacts of climate change on tropical forests require information on the relative vulnerabilities and roles of the biological components of these unusually complex systems. Central to the structure and function of any ecosystem - and the subject of this paper - is its flora, the energetic base for co-occurring heterotrophs. Much data indicate that arboreal flora (the epiphytes), those plants anchored in the forest canopy without access to the ground, occupy unusually climate-defined ecospace compared with co-occurring types such as the supporting trees. This report also describes how the epiphytes influence adjacent biota and whole-system processes, specifically those concerned with energetics, hydrology, and mineral cycling. Second, a mechanistic explanation for the exceptionally climate-sensitive nature of arboreal flora is provided. Finally, points one and two are used to make the case that arboreal flora represent a weak link in the integrity of certain types of forest, especially cloud forest and other types at lower elevations well known for their extraordinarily diverse biota. These plants, more than most, should provide early indications of floristic response to climate change throughout much of the tropics, but particularly in montane regions.

Loope, Lloyd L., and Thomas W. Giambelluca. 1998. "Vulnerability of Island Tropical Montane Cloud Forests to Climate Change, with Special Reference to East Maui, Hawaii," Climatic Change, Vol. 39, No. 2-3, July, pp. 503-517.
ABSTRACT: Island tropical montane cloud forests may be among the most sensitive of the world's ecosystems to global climate change. Measurements in and above a montane cloud forest on East Maui, Hawaii, document steep microclimatic gradients. Relatively small climate-driven shifts in patterns of atmospheric circulation are likely to trigger major local changes in rainfall, cloud cover, and humidity. Increased interannual variability in precipitation and hurricane incidence would provide additional stresses on island biota that are highly vulnerable to disturbance-related invasion of non-native species. Because of the exceptional sensitivity of these microclimates and forests to change, they may provide valuable 'listening posts' for detecting the onset of human-induced global climate change.

Bawa, Kamaljit S., and S. Dayanandan. 1998. "Global Climate Change and Tropical Forest Genetic Resources," Climatic Change, Vol. 39, No. 2-3, July, pp. 473-485.
ABSTRACT: Global climate change may have a serious impact on genetic resources in tropical forest trees. Genetic diversity plays a critical role in the survival of populations in rapidly changing environments. Furthermore, most tropical plant species are known to have unique ecological niches, and therefore changes in climate may directly affect the distribution of biomes, ecosystems, and constituent species. Climate change may also indirectly affect plant genetic resources through effects on phenology, breeding systems, and plant-pollinator and plant seed disperser interactions, and may reduce genetic diversity and reproductive output. As a consequence, population densities may be reduced leading to reduction in genetic diversity through genetic drift and inbreeding. Tropical forest plants may respond to climate change through phenotypic plasticity, adaptive evolution, migration to suitable site, or extinction. However, the potential to respond is limited by a rapid pace of change and the non-availability of alternate habitats due to past and present trends of deforestation. Thus climate change may result in extinction of many populations and species. Our ability to estimate the precise response of tropical forest ecosystems to climate change is limited by lack of long-term data on parameters that might be affected by climate change. Collection of correlative data from long-term monitoring of climate as well as population and community responses at selected sites offer the most cost-effective way to understand the effects of climate change on tropical tree populations. However, mitigation strategies need to be implemented immediately. Because many effects of climate change may be similar to the effects of habitat alteration and fragmentation, protected areas and buffer zones should be enlarged, with an emphasis on connectivity among conserved landscapes. Taxa that are likely to become extinct should be identified and protected through ex situ conservation programs.

Coley, Phyllis D. 1998. "Possible Effects of Climate Change on Plant/Herbivore Interactions in Moist Tropical Forests," Climatic Change, Vol. 39, No. 2-3, July, pp. 455-472.
ABSTRACT: The interactions between plants and herbivores are key determinants of community structure world wide. Their role is particularly important in lowland tropical rain forests where rates of herbivory are higher, plants are better defended chemically and physically, and herbivores have specialized diets. In contrast to the temperate zone, most of the herbivory in the tropics occurs on ephemeral young leaves (>70%), which requires herbivores to have finely tuned host-finding abilities. As a consequence of these tight ecological and evolutionary linkages, the interplay between plants and herbivores in the tropics may be more susceptible to perturbations of climate change.
Increases in global temperature, atmospheric CO2, and the length of the dry season are all likely to have ramifications for plant/herbivore interactions in the tropics. Here I extrapolate from our current and incomplete understanding of the mechanisms regulating plant/herbivore interactions and present a scenario for possible trends under a changing climate. Although elevated CO2 tends to enhance plant growth rates, the larger effects of increased drought stress will probably result in lower growth. In atmospheres experimentally enriched in CO2, the nutritional quality of leaves declines substantially due to a dilution of nitrogen by 10-30%. This response is buffered in plant species associated with nitrogen fixers. Elevated CO2 should also cause a slight decrease in nitrogen-based defenses (e.g., alkaloids) and a slight increase in carbon-based defenses (e.g., tannins). The most dramatic and robust predicted effect of climate change is on rates of herbivory. Lower foliar nitrogen due to CO2 fertilization of plants causes an increase in consumption per herbivore by as much as 40%, and unusually severe drought appears to cause herbivore populations to explode. In areas where elevated CO2 is combined with drying, rates of herbivory may rise 2-4 fold. The frequency of insect outbreaks is also expected to increase. Higher herbivory should further reduce plant growth rates, perhaps favoring plant species that are well-defended or fix nitrogen. The predicted increase in the number of herbivores is primarily due to relaxed pressure from predators and parasitoids. Elevated temperatures may increase herbivore developmental times, affording them partial escape from discovery by natural enemies, and drought appears to decimate parasitoid populations. The expected decline in parasitoid numbers may be due to direct effects of dry season drought or to the relative scarcity of herbivores during that period. As a consequence, the relative abundance of species will change, and overall biodiversity should decline.

Corlett , Richard T.. and James V. Lafrankie, Jr. 1998. "Potential Impacts of Climate Change on Tropical Asian Forests Through an Influence on Phenology," Climatic Change, Vol. 39, No. 2-3, July, pp. 439-453.
ABSTRACT: Changes in plant phenology will be one of the earliest responses to rapid global climate change and could potentially have serious consequences both for plants and for animals that depend on periodically available plant resources. Phenological patterns are most diverse and least understood in the tropics. In those parts of tropical Asia where low temperature or drought impose a seasonal rest period, regular annual cycles of growth and reproduction predominate at the individual, population, and community level. In aseasonal areas, individuals and populations show a range of sub- to supra-annual periodicities, with an overall supra-annual reproductive periodicity at the community level. There is no evidence for photoperiod control of phenology in the Asian tropics, and seasonal changes in temperature are a likely factor only near the northern margins. An opportunistic response to water availability is the simplest explanation for most observed patterns where water is seasonally limiting, while the great diversity of phenological patterns in the aseasonal tropics suggests an equal diversity of controls. The robustness of current phenological patterns to high interannual and spatial variability suggests that most plant species will not be seriously affected by the phenological consequences alone of climate change. However, some individual plant species may suffer, and the consequences of changes in plant phenology for flower- and fruit-dependent animals in fragmented forests could be serious.

Whitmore, T. C. 1998. "Potential Impact of Climatic Change on Tropical Rain Forest Seedlings and Forest Regeneration," Climatic Change, Vol. 39, No. 2-3, July, pp. 429-438.
ABSTRACT: Tropical rain forests are dynamic and continually regenerating by growth of seedlings up from the forest floor into canopy gaps that form on a cycle of usually a century of more in length. Changes in seedling establishment, survival, and release in gaps could thus change canopy species composition for a long time. Of likely climatic changes, evidence is presented that cyclone occurrence and increased rainfall seasonality could have important effects on seedling ecology. These forests and their species have lived through big Pleistocene and Holocene climatic changes, but today they are fragmented by human impact and so have less resilience to future climatic change. Management to accommodate climatic change should aim to reduce fragmentation and also canopy opening during logging operations. These are the same practices as advocated for biodiversity conservation. Tropical seasonal forests are also likely to be altered by expected climatic change, and also mainly at their regeneration stage.

Borchert, Rolf. 1998. "Responses of Tropical Trees to Rainfall Seasonality and its Long-Term Changes," Climatic Change, Vol. 39, No. 2-3, pp. 381-393.
ABSTRACT: Seasonality and physiognomy of tropical forests are mainly determined by the amount of annual rainfall and its seasonal distribution. Climatic change scenarios predict that global warming will result in reduced annual rainfall and longer dry seasons for some, but not all, tropical rainforests. Tropical trees can reduce the impact of seasonal drought by adaptive mechanisms such as leaf shedding or stem succulence and by utilization of soil water reserves, which enable the maintenance of an evergreen canopy during periods of low rainfall. Correlations between climate and responses of tropical trees are therefore poor and the responses of tropical rainforests to climatic changes are hard to predict. Predicted climate change is unlikely to affect the physiognomy of rainforests with high annual rainfall and low seasonality. Seasonal evergreen forests which depend on the use of soil water reserves will be replaced by more drought-tolerant semideciduous forests, once rainfall becomes insufficient to replenish soil water reserves regularly. As the limits of drought tolerance of tropical rainforests are not known, rate and extent of future changes cannot be predicted.

Körner, Christian. 1998. "Tropical Forests in a Co2-Rich World," Climatic Change, Vol. 39, No. 2-3, pp. 297-315.
ABSTRACT: Tropical forests resemble, besides their enormous genetic diversity, the single largest biomass carbon pool in the world. Only a 'small' annual increase of this pool could trap the current surplus of atmospheric CO2. The fact that this is not happening already today (after the world has seen a 27% increase in atmospheric CO2 in only 150 years) sets the boundaries of the likely trends to be expected in the future. In contrast to the possibly small overall responses of the tropical forest carbon pool, individual plant responses to CO2 enrichment will be significant. Since species and their genotypes will not respond in identical ways, selective processes will be induced which will lead to new community structures and alterations of numerous plant-plant, plant-animal and plant-microbe interactions. Examples are provided for such subtile CO2 effects, measured both in the greenhouse and in the field. From what is known currently it is concluded that in closed humid tropical forests leaf area index is unlikely to increase, mineral nutrient and water demand may (at least temporarily) become reduced, and leaf tissue quality plus associated consumer behavior will be altered. The big unknown is the behavior of tropical soils and their microflora and fauna. There is a realistic possibility that carbon turnover will be increased in tropical forests in a CO2-enriched world, which would have substantial implications for nutrient cycling.