Time-dependent effects of climate and drought on tree growth in a Neotropical dry forest: Short-term tolerance vs. long-term sensitivity (original) (raw)
Related papers
2014
We analyzed the effects of climate and drought on radial growth using dendrochronology in seven deciduous tree species coexisting in a Bolivian tropical dry forest subjected to seasonal drought. Precipitation, temperature and a multiscalar drought index were related to tree-ring width data at different timescales (from one month to 42 years). Precipitation affected positively tree growth in all species, mainly during the wet season, while temperature affected it negatively in five species. Tree growth responses to precipitation and temperature were species-specific and peaked at short-time scales, specifically from one to nine months. At inter-annual scales tree growth always responded positively to less dry conditions at shorttime scales, particularly from two to seven months, and also at long-time scales from six to 30 years. Tree growth was mainly sensitive to multi-annual droughts and such sensitivity differed among species. Our findings suggest that tree species of the studied tropical dry forest are predominantly sensitive in terms of growth reduction to long-lasting droughts. This time-dependency of growth responses to drought should be explicitly considered as an additional constraint of the community dynamics in evaluations of the future responses of tropical dry forests to climate warming.
PLoS ONE, 2013
A seasonal period of water deficit characterizes tropical dry forests (TDFs). There, sympatric tree species exhibit a diversity of growth rates, functional traits, and responses to drought, suggesting that each species may possess different strategies to grow under different conditions of water availability. The evaluation of the long-term growth responses to changes in the soil water balance should provide an understanding of how and when coexisting tree species respond to water deficit in TDFs. Furthermore, such differential growth responses may be linked to functional traits related to water storage and conductance. We used dendrochronology and climate data to retrospectively assess how the radial growth of seven coexisting deciduous tree species responded to the seasonal soil water balance in a Bolivian TDF. Linear mixed-effects models were used to quantify the relationships between basal area increment and seasonal water balance. We related these relationships with wood density and sapwood production to assess if they affect the growth responses to climate. The growth of all species responded positively to water balance during the wet season, but such responses differed among species as a function of their wood density. For instance, species with a strong growth response to water availability averaged a low wood density which may facilitate the storage of water in the stem. By contrast, species with very dense wood were those whose growth was less sensitive to water availability. Coexisting tree species thus show differential growth responses to changes in soil water balance during the wet season. Our findings also provide a link between wood density, a trait related to the ability of trees to store water in the stem, and wood formation in response to water availability.
Water Availability Is the Main Climate Driver of Neotropical Tree Growth
PLoS ONE, 2012
N Climate models for the coming century predict rainfall reduction in the Amazonian region, including change in water availability for tropical rainforests. Here, we test the extent to which climate variables related to water regime, temperature and irradiance shape the growth trajectories of neotropical trees. N We developed a diameter growth model explicitly designed to work with asynchronous climate and growth data. Growth trajectories of 205 individual trees from 54 neotropical species censused every 2 months over a 4-year period were used to rank 9 climate variables and find the best predictive model. N About 9% of the individual variation in tree growth was imputable to the seasonal variation of climate. Relative extractable water was the main predictor and alone explained more than 60% of the climate effect on tree growth, i.e. 5.4% of the individual variation in tree growth. Furthermore, the global annual tree growth was more dependent on the diameter increment at the onset of the rain season than on the duration of dry season. N The best predictive model included 3 climate variables: relative extractable water, minimum temperature and irradiance. The root mean squared error of prediction (0.035 mm.d -1 ) was slightly above the mean value of the growth (0.026 mm.d -1 ). N Amongst climate variables, we highlight the predominant role of water availability in determining seasonal variation in tree growth of neotropical forest trees and the need to include these relationships in forest simulators to test, in silico, the impact of different climate scenarios on the future dynamics of the rainforest.
Dendrochronologia, 2018
Tree-ring research in the highland tropics and subtropics represents a major frontier for understanding climate-growth relationships. Nonetheless, there are many lowland regionsincluding the South American Pampa biomewith scarce tree ring data. We present the first two tree-ring chronologies for Scutia buxifolia in subtropical Southeastern South America (SESA), using 54 series from 29 trees in two sites in northern and southern Uruguay. We cross-dated annual rings and compared tree growth from 1950-2012 with regional climate variability, including rainfall, temperature and the Palmer Drought Severity Index-PDSI, the El Niño Southern Oscillation (ENSO) and the Southern Annular Mode (SAM). Overall, ring width variability was highly responsive to climate signals linked to water availability. For example, tree growth was positively correlated with accumulated rainfall in the summer-fall prior to ring formation for both chronologies. Summer climate conditions were key for tree growth, as shown by a negative effect of hot summers and a positive correlation with PDSI in late austral summer. The El Niño phase in late spring/early summer favored an increase in rainfall and annual tree growth, while the La Niña phase was associated with less rainfall and reduced tree growth. Extratropical climate factors such as SAM had an equally relevant effect on tree growth, whereby the positive phase of SAM had a negative effect over radial growth. These findings demonstrate the potential for dendroclimatic research and climate reconstruction in a region with scarce tree-ring data. They also improve the understanding of how climate variability may affect woody growth in native forestsan extremely limited ecosystem in the Pampa biome.
Oecologia, 2005
Many tropical regions show one distinct dry season. Often, this seasonality induces cambial dormancy of trees, particularly if these belong to deciduous species. This will often lead to the formation of annual rings. The aim of this study was to determine whether tree species in the Bolivian Amazon region form annual rings and to study the influence of the total amount and seasonal distribution of rainfall on diameter growth. Ring widths were measured on stem discs of a total of 154 trees belonging to six rain forest species. By correlating ring width and monthly rainfall data we proved the annual character of the tree rings for four of our study species. For two other species the annual character was proved by counting rings on trees of known age and by radiocarbon dating. The results of the climategrowth analysis show a positive relationship between tree growth and rainfall in certain periods of the year, indicating that rainfall plays a major role in tree growth. Three species showed a strong relationship with rainfall at the beginning of the rainy season, while one species is most sensitive to the rainfall at the end of the previous growing season. These results clearly demonstrate that tree ring analysis can be successfully applied in the tropics and that it is a promising method for various research disciplines.
Theoretical and Applied Climatology, 2015
We explored the relationship between tree growth in two tropical species and local and large-scale climate variability in Southeastern Brazil. Tree ring width chronologies of Tectona grandis (teak) and Pinus caribaea (Caribbean pine) trees were compared with local (Water Requirement Satisfaction Index-WRSI, Standardized Precipitation Index-SPI, and Palmer Drought Severity Index-PDSI) and large-scale climate indices that analyze the equatorial pacific sea surface temperature (Trans-Niño Index-TNI and Niño-3.4-N3.4) and atmospheric circulation variations in the Southern Hemisphere (Antarctic Oscillation-AAO). Teak trees showed positive correlation with three indices in the current summer and fall. A significant correlation between WRSI index and Caribbean pine was observed in the dry season preceding tree ring formation. The influence of large-scale climate patterns was observed only for TNI and AAO, where there was a radial growth reduction in months preceding the growing season with positive values of the TNI in teak trees and radial growth increase (decrease) during December (March) to February (May) of the previous (current) growing season with positive phase of the AAO in teak (Caribbean pine) trees. The development of a new dendroclimatological study in Southeastern Brazil sheds light to local and large-scale climate influence on tree growth in recent decades, contributing in future climate change studies.
Drought and the interannual variability of stem growth in an aseasonal, everwet forest
Biotropica, 2019
Linking drought to the timing of physiological processes governing tree growth remains one limitation in forecasting climate change effects on tropical trees. Using dendrometers, we measured fine-scale growth for 96 trees of 25 species from 2013 to 2016 in an everwet forest in Puerto Rico. Rainfall over this time span varied, including an unusual, severe El Niño drought in 2015. We assessed how growing season onset, median day, conclusion, and length varied with absolute growth rate and tree size over time. Stem growth was seasonal, beginning in February, peaking in July, and ending in November. Species growth rates varied between 0 and 8 mm/year and correlated weakly with specific leaf area, leaf phosphorus, and leaf nitrogen, and to a lesser degree with wood specific gravity and plant height. Drought and tree growth were decoupled, and drought lengthened and increased variation in growing season length. During the 2015 drought, many trees terminated growth early but did not necessarily grow less. In the year following drought, trees grew more over a shorter growing season, with many smaller trees showing a post-drought increase in growth. We attribute the increased growth of smaller trees to release from light limitation as the canopy thinned because of the drought, and less inferred hydraulic stress than larger trees during drought. Soil type accounted for interannual and interspecific differences, with the finest Zarzal clays reducing tree growth. We conclude that drought affects the phenological timing of tree growth and favors the postdrought growth of smaller, sub-canopy trees in this everwet forest.
Dendrochronologia, 2019
Tropical dry forests (TDF) are highly important tropical forest ecosystems. Yet, these forests are highly threatened, usually neglected and only poorly studied. Understanding the long-term influences of environmental conditions on tree growth in these forests is crucial to understand the functioning, carbon dynamics and potential responses to future climate change of these forests. Dendrochronolgy can be used as a tool to provide these insights but has only scantly been applied in (dry) tropical forests. Here we evaluate the dendrochronological potential of four Caatinga neotropical dry forest tree species-Aspidosperma pyrifolium, Ziziphus joazeiro, Tabebuia aurea, and Libidibia ferreacollected in two locations in northeastern Brazil (Sergipe state). We provide an anatomical characterization of the ring boundaries for the four species and investigate correlations of their growth with local and regional climatic variables. All four species form annual rings and show high inter-correlation (up to 0.806) and sensitivity (up to 0.565). Growth of all species correlated with local precipitation as well as with seasurface temperatures in the tropical Atlantic and/or tropical Pacific oceans. We also show teleconnections between growth and the El Niño South Oscillation. The strong dependence of tree on precipitation is worrisome, considering that climate change scenarios forecast increased drought conditions in the Caatinga dry forest. Including more species and expanding dendrochronological studies to more areas would greatly improve our understanding of tree growth and functioning in TDFs. This type of knowledge is essential to assist the conservation, management and restoration of these critical tropical ecosystems.
Are Commonly Measured Functional Traits Involved in Tropical Tree Responses to Climate?
International Journal of Ecology, 2014
Climate models predict significant rainfall reduction in Amazonia, reducing water availability for trees. We present how functional traits modulate the tree growth response to climate. We used data from 3 years of bimestrial growth measurements for 204 trees of 53 species in the forest of Paracou, French Guiana. We integrated climate variables from an eddy covariance tower and functional trait values describing life history, leaf, and stem economics. Our results indicated that the measured functional traits are to some extent linked to the response of trees to climate but they are poor predictors of the tree climate-induced growth variation. Tree growth was affected by water availability for most of the species with different species growth strategies in drought conditions. These strategies were linked to some functional traits, especially maximum height and wood density. These results suggest that (i) trees seem adapted to the dry season at Paracou but they show different growth responses to drought, (ii) drought response is linked to growth strategy and is partly explained by functional traits, and (iii) the limited part of the variation of tree growth explained by functional traits may be a strong limiting factor for the prediction of tree growth response to climate.
Tree-growth responses across environmental gradients in subtropical Argentinean forests
Subtropical forests in montane ecosystems grow under a wide range of environmental conditions. However, little is known about the growth responses of subtropical trees to climate along ecological gradients. To assess how, and to what extent climate controls tree growth, we analyzed tree responses to climate for 15 chronologies from 4 different species (Schinopsis lorentzii, Juglans australis, Cedrela lilloi, Alnus acuminata) across a variety of environments in subtropical forests from northwestern Argentina (22-28°S, 64-66°W). Using correlation and principal component analysis, site and species differences in tree-growth responses to precipitation and temperature were determined along the elevation gradient from the dry-warm Chaco lowlands to the wet-cool montane Yungas. Our results show that species responses differ according to the severity in climate conditions along the elevation gradient. At sites with unfavorable conditions, mainly located at the extremes of the environmental gradient, responses of different species to climate variations are similar; in contrast, at sites with relatively mild conditions, tree growth displays a large variety of responses reflecting differences in both local environmental conditions and species physiology. Our research suggests that individualistic responses to environmental variability would determine differences in the type and timing of the responses of dominant trees to climate, which ultimately may shift species' assemblages in montane subtropical regions of South America under future climate changes.