scholarly journals Fire Impacts on Recruitment Dynamics in a Seasonal Tropical Forest in Continental Southeast Asia

Forests ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 116
Author(s):  
Kanokporn Kaewsong ◽  
Daniel J. Johnson ◽  
Sarayudh Bunyavejchewin ◽  
Patrick J. Baker
Keyword(s):  
Southeast Asia ◽  
Tropical Forests ◽  
Functional Traits ◽  
Tree Species ◽  
Forest Dynamics ◽  
Fire Intensity ◽  
Spatial And Temporal Variability ◽  
Tree Recruitment ◽  
In Fire

The effects of forest fires on tree recruitment dynamics in tropical forests is important for predicting forest dynamics and ecosystem function in Southeast Asia. To our knowledge, no studies have examined the effects of fire intensity on community-level recruitment patterns in tropical forests due to the rarity of long-term observation datasets in fire-impacted tropical forests and the difficulty of quantifying fire intensity. We addressed two questions: (1) is tree recruitment among species affected by fire intensity? and if so, (2) are there specific plant functional traits associated with these responses? We used data from a long-term forest dynamics plot at the Huai Kha Khaeng (HKK) Wildlife Sanctuary in Thailand. The HKK plot occurs in a strongly seasonal tropical environment and has experienced several fires since its establishment in 1994. We found 46 tree species (52% of the 89 species analysed) showed evidence of reduced recruitment rates with increasing fire intensities during the most recent fire in 2005. Tree species in this flammable landscape have various leaf and wood functional traits associated with fire. Spatial and temporal variability in fire activity may lead to alterations in long-term taxonomic and functional composition of the forest due to selection on fire-related traits.

scholarly journals Modeling the long-term dynamics of tropical forests: from leaf traits to whole-tree growth patterns

2020 ◽  
Author(s):  
Gunnar Petter ◽  
Holger Kreft ◽  
Yongzhi Ong ◽  
Gerhard Zotz ◽  
Juliano Sarmento Cabral
Keyword(s):  
Tropical Forests ◽  
Functional Traits ◽  
Tree Growth ◽  
Tree Species ◽  
Leaf Traits ◽  
Forest Stand ◽  
Growth Patterns ◽  
Leaf Economic Spectrum ◽  
Individual Trees

AbstractTropical forests are the most diverse terrestrial ecosystems and home to numerous tree species with diverse ecological strategies competing for resources in space and time. Functional traits influence the ecophysiological performance of tree species, yet the relationship between traits and emergent long-term growth pattern is poorly understood. Here, we present a novel 3D forest stand model in which growth patterns of individual trees and forest stands are emergent properties of leaf traits. Individual trees are simulated as 3D functional-structural tree models (FSTMs), considering branches up to the second order and leaf dynamics at a resolution of one m3. Each species is characterized by a set of leaf traits that corresponds to a specific position on the leaf economic spectrum and determines light-driven carbon assimilation, respiration and mortality rates. Applying principles of the pipe model theory, these leaf scale-processes are coupled with within-tree carbon allocation, i.e., 3D tree growth emerges from low-level processes. By integrating these FSTMs into a dynamic forest stand model, we go beyond modern stand models to integrate structurally-detailed internal physiological processes with interspecific competition, and interactions with the environment in diverse tree communities. For model calibration and validation, we simultaneously compared a large number of emergent patterns at both the tree and forest levels in a pattern-oriented modeling framework. At the tree level, varying specific leaf area and correlated leaf traits determined the maximum height and age of a tree, as well as its size-dependent growth rate and shade tolerance. Trait variations along the leaf economic spectrum led to a continuous transition from fast-growing, short-lived and shade-intolerant to slow-growing, long-lived and shade-tolerant trees. These emerging patterns resembled well-known functional tree types, indicating a fundamental impact of leaf traits on long-term growth patterns. At the forest level, a large number of patterns taken from lowland Neotropical forests were reproduced, indicating that our forest model simulates structurally realistic forests over long time spans. Our ecophysiological approach improves the understanding of how leaf level processes scale up to the tree and the stand level, and facilitates the development of next-generation forest models for species-rich forests in which tree performance emerges directly from functional traits.

scholarly journals Tropical Dry Forest Resilience to Fire Depends on Fire Frequency and Climate

2021 ◽  
Vol 4 ◽  
Author(s):  
Maximilian Hartung ◽  
Geovana Carreño-Rocabado ◽  
Marielos Peña-Claros ◽  
Masha T. van der Sande
Keyword(s):  
Tropical Forests ◽  
Tropical Dry Forest ◽  
Remote Sensing Data ◽  
Fire Frequency ◽  
Dry Forest ◽  
Fire Disturbance ◽  
Fire Intensity ◽  
Forest Resilience ◽  
Landsat Satellite ◽  
In Fire

Wildfires are becoming increasingly frequent and devastating in many tropical forests. Although seasonally dry tropical forests (SDTF) are among the most fire-threatened ecosystems, their long-term response to frequent wildfires remains largely unknown. This study is among the first to investigate the resilience in response to fire of the Chiquitano SDTF in Bolivia, a large ecoregion that has seen an unprecedented increase in fire intensity and frequency in recent years. We used remote sensing data to assess at a large regional and temporal scale (two decades) how fire frequency and environmental factors determine the resilience of the vegetation to fire disturbance. Resilience was measured as the resistance to fire damage and post-fire recovery. Both parameters were monitored for forested areas that burned once (F1), twice (F2), and three times (F3) between 2000 and 2010 and compared to unburned forests. Resistance and recovery were analyzed using time series of the Normalized Burn Ratio (NBR) index derived from Landsat satellite imagery, and climatic, topographic, and a human development-related variable used to evaluate their influence on resilience. The overall resilience was lowest in forests that burned twice and was higher in forests that burned three times, indicating a possible transition state in fire resilience, probably because forests become increasingly adapted during recurrent fires. Climatic variables, particularly rainfall, were most influential in determining resilience. Our results indicate that the Chiquitano dry forest is relatively resilient to recurring fires, has the capacity to recover and adapt, and that climatic differences are the main determinants of the spatial variation observed in resilience. Nevertheless, further research is needed to understand the effect of the higher frequency and intensity of fires expected in the future due to climate change and land use change, which may pose a greater threat to forest resilience.

scholarly journals Through enhanced tree dynamics carbon dioxide enrichment may cause tropical forests to lose carbon

2004 ◽  
Vol 359 (1443) ◽  
pp. 493-498 ◽  
Author(s):  
Christian Körner
Keyword(s):  
Tropical Forests ◽  
Forest Dynamics ◽  
Forest Inventories ◽  
C Storage ◽  
Theoretical Approaches ◽  
C Cycle ◽  
Net Uptake ◽  
And Storage ◽  
Biodiversity Effects

The fixation and storage of C by tropical forests, which contain close to half of the globe's biomass C, may be affected by elevated atmospheric CO 2 concentration. Classical theoretical approaches assume a uniform stimulation of photosynthesis and growth across taxa. Direct assessments of the C balance either by flux studies or by repeated forest inventories also suggest a current net uptake, although magnitudes sometimes exceed those missing required to balance the global C cycle. Reasons for such discrepancies may lie in the nature of forest dynamics and in differential responses of taxa or plant functional types. In this contribution I argue that CO 2 enrichment may cause forests to become more dynamic and that faster tree turnover may in fact convert a stimulatory effect of elevated CO 2 on photosynthesis and growth into a long–term net biomass C loss by favouring shorter–lived trees of lower wood density. At the least, this is a scenario that deserves inclusion into long–term projections of the C relations of tropical forests. Species and plant functional type specific responses (‘biodiversity effects’) and forest dynamics need to be accounted for in projections of future C storage and cycling in tropical forests.

Fire effects on the spatial patterns of soil resources in a Nicaraguan wet tropical forest

2005 ◽  
Vol 21 (4) ◽  
pp. 435-444 ◽  
Author(s):  
Brent C. Blair
Keyword(s):  
Leaf Litter ◽  
Tropical Forests ◽  
Forest Fires ◽  
Soil Heterogeneity ◽  
Fire Effects ◽  
Fire Intensity ◽  
Vegetative Cover ◽  
Soil Resources ◽  
In Fire ◽  
The Impact

Anthropogenic wildfires are becoming increasingly frequent in wet tropical forests. This trend follows that of other anthropogenic disturbances, which are now acute and widespread. Fires pose a potentially serious threat to tropical forests. However, little is known about the impact of unintended forest fires on below-ground resources in these ecosystems. This study investigated the influence of fires on the distribution and variability of soil resources on two sets of 50×50-m burned and unburned plots in a Nicaraguan rain forest. Samples were collected at 5-m intervals throughout each plot as well as subsamples at 50-cm intervals. Geostatistical techniques as well as univariate statistics were used to quantify the spatial autocorrelation and variability of selected nutrients (N, P and K), carbon and standing leaf litter. Most variability in this forest was spatially dependent at a scale of 30 m or less. However the average range of autocorrelations varied greatly between properties and sites. Burning altered soil heterogeneity by decreasing the range over which soil properties were autocorrelated. Overall the average patch size (range) for nitrogen was reduced by 7%, phosphorus by 52%, potassium by 60% and carbon by 43%. While phosphorus and leaf litter increased in the burned plots compared to unburned plots, potassium was not different. Nitrogen and carbon did not display a consistent pattern between burning regimes and this may be explained by variation in fire intensity. Leaf litter measurements did not correlate with measured soil nutrients within plots. Observed changes in the burned forest were likely a result of both the intensity of burning and change in vegetative cover between the time of the fires and soil sampling.

scholarly journals On the spatial and temporal variability of ENSO precipitation and drought teleconnection in mainland Southeast Asia

2015 ◽  
Vol 11 (6) ◽  
pp. 5307-5343 ◽  
Author(s):  
T. A. Räsänen ◽  
V. Lindgren ◽  
J. H. A. Guillaume ◽  
B. M. Buckley ◽  
M. Kummu
Keyword(s):  
Southeast Asia ◽  
Southern Oscillation ◽  
Drought Severity ◽  
Spatial And Temporal Variability ◽  
Severe Drought ◽  
Seasonal Evolution ◽  
Enso Events ◽  
Precipitation Anomalies ◽  
Mainland Southeast Asia

Abstract. The variability in the hydroclimate over mainland Southeast Asia is strongly influenced by the El Niño–Southern Oscillation (ENSO) phenomenon, which has been linked to severe drought and floods that profoundly influence human societies and ecosystems alike. However, the spatial characteristics and long-term stationarity of ENSO's influence in the region are not well understood. We thus aim to analyse seasonal evolution and spatial variations in the effect of ENSO on precipitation over the period of 1980–2013, and long-term variation in the ENSO-teleconnection using tree-ring derived Palmer Drought Severity Indices (PDSI) that span from 1650–2004. We found that the majority of the study area is under the influence of ENSO, which has affected the region's hydroclimate over the majority (96 %) of the 355 year study period. Our results further indicate that there is a pattern of seasonal evolution of precipitation anomalies during ENSO. However, considerable variability in the ENSO's influence is revealed: the strength of ENSO's influence was found to vary in time and space, and the different ENSO events resulted in varying precipitation anomalies. Additional research is needed to investigate how this variation in ENSO teleconnection is influenced by other factors, such as the properties of the ENSO events and other ocean and atmospheric phenomena. In general, the high variability we found in ENSO teleconnection combined with limitations of current knowledge, suggests that the adaptation to extremes in hydroclimate in mainland Southeast Asia needs to go beyond "predict-and-control" and recognise both uncertainty and complexity as fundamental principles.

scholarly journals Functional traits of tree species with phylogenetic signal co-vary with environmental niches in two large forest dynamics plots

2014 ◽  
Vol 7 (2) ◽  
pp. 115-125 ◽  
Author(s):  
Jie Yang ◽  
Xiuqin Ci ◽  
Mengmeng Lu ◽  
Guocheng Zhang ◽  
Min Cao ◽  
...  
Keyword(s):  
Functional Traits ◽  
Tree Species ◽  
Forest Dynamics ◽  
Phylogenetic Signal

scholarly journals In the line of fire: the peatlands of Southeast Asia

2016 ◽  
Vol 371 (1696) ◽  
pp. 20150176 ◽  
Author(s):  
S. E. Page ◽  
A. Hooijer
Keyword(s):  
Southeast Asia ◽  
Management Strategies ◽  
Fire Risk ◽  
Management Options ◽  
C Cycle ◽  
Warming World ◽  
Northern Peatlands ◽  
In Fire ◽  
Global Carbon

Peatlands are a significant component of the global carbon (C) cycle, yet despite their role as a long-term C sink throughout the Holocene, they are increasingly vulnerable to destabilization. Nowhere is this shift from sink to source happening more rapidly than in Southeast Asia, and nowhere else are the combined pressures of land-use change and fire on peatland ecosystem C dynamics more evident nor the consequences more apparent. This review focuses on the peatlands of this region, tracing the link between deforestation and drainage and accelerating C emissions arising from peat mineralization and fire. It focuses on the implications of the recent increase in fire occurrence for air quality, human health, ecosystem resilience and the global C cycle. The scale and controls on peat-driven C emissions are addressed, noting that although fires cause large, temporary peaks in C flux to the atmosphere, year-round emissions from peat mineralization are of a similar magnitude. The review concludes by advocating land management options to reduce future fire risk as part of wider peatland management strategies, while also proposing that this region's peat fire dynamic could become increasingly relevant to northern peatlands in a warming world. This article is part of the themed issue ‘The interaction of fire and mankind’.

scholarly journals On the spatial and temporal variability of ENSO precipitation and drought teleconnection in mainland Southeast Asia

2016 ◽  
Vol 12 (9) ◽  
pp. 1889-1905 ◽  
Author(s):  
Timo A. Räsänen ◽  
Ville Lindgren ◽  
Joseph H. A. Guillaume ◽  
Brendan M. Buckley ◽  
Matti Kummu
Keyword(s):  
Southeast Asia ◽  
Southern Oscillation ◽  
Drought Severity ◽  
Spatial And Temporal Variability ◽  
Seasonal Evolution ◽  
Enso Events ◽  
Term Variation ◽  
Precipitation Anomalies ◽  
Mainland Southeast Asia

Abstract. The variability of the hydroclimate over mainland Southeast Asia is strongly influenced by the El Niño–Southern Oscillation (ENSO), which has been linked to severe droughts and floods that profoundly influence human societies and ecosystems alike. Although the significance of ENSO is well understood, there are still limitations in the understanding of its effects on hydroclimate, particularly with regard to understanding the spatio-temporal characteristics and the long-term variation of its effects. Therefore we analysed the seasonal evolution and spatial variations in the effect of ENSO on precipitation over the period of 1980–2013 and the long-term variation in the ENSO teleconnection using tree-ring-derived Palmer drought severity indices (PDSIs) for the March–May season that span over the time period 1650–2004. The analyses provided an improved understanding of the seasonal evolution of the precipitation anomalies during ENSO events. The effects of ENSO were found to be most consistent and expressed over the largest areal extents during March–May of the year when the ENSO events decay. On a longer timescale, we found that ENSO has affected the region's March–May hydroclimate over the majority (95 %) of the 355-year study period and that during half (52 %) of the time ENSO caused a significant increase in hydroclimatic variability. The majority of the extremely wet and dry March–May seasons also occurred during ENSO events. However, considerable variability in ENSO's influence was revealed: the spatial pattern of precipitation anomalies varied between individual ENSO events, and the strength of ENSO's influence was found to vary through time. Given the high variability in ENSO teleconnection that we described and the limitations of the current understanding of the effects of ENSO, we suggest that the adaptation to ENSO-related extremes in hydroclimate over mainland Southeast Asia needs to recognise uncertainty as an inherent part of adaptation, must go beyond "predict and control", and should seek adaptation opportunities widely within society.

scholarly journals Ecosystem restoration in fire-managed savanna woodlands: Effects on biodiversity, local livelihoods and fire intensity

AMBIO ◽  
2020 ◽  
Vol 50 (1) ◽  
pp. 190-202 ◽  
Author(s):  
Maria Ulrika Johansson ◽  
Firew Bekele Abebe ◽  
Sileshi Nemomissa ◽  
Tamrat Bekele ◽  
Kristoffer Hylander
Keyword(s):  
Carbon Storage ◽  
Fire Intensity ◽  
Grass Species ◽  
Tree Seedlings ◽  
Mature Trees ◽  
Grazing Exclusion ◽  
Local Livelihoods ◽  
In Fire ◽  
Experimental Burns

AbstractEthiopia aims to restore 15 million ha degraded forests and woodlands, but effects on the potentially contrasting goals of long-term carbon storage, biodiversity and sustainable livelihoods are unknown. To quantify the effects of grazing exclusion on vegetation and fire behaviour, we established six 30 × 30 m fenced exclosures with grazed controls, in a mesic wooded savanna. Experimental burns were done after 1.5 years. Tree seedlings were few but more common inside fences. Field layer cover and biomass increased inside fences, and grass species increased in numbers and cover. Fire intensity was higher inside fences, killing shrubs and saplings but not mature trees. Interviews confirmed that overgrazing has resulted in “cool fires”, causing shrub encroachment. High-intensity fires occurred in the 1980s after a zoonotic disease killed most livestock. Short-term increase in carbon storage through fire and grazing exclusion may lead to loss of pasture, and in the long-term increased wildfire risk.

Interspecific variation in branch and leaf traits among three Syzygium tree species from different successional tropical forests

2015 ◽  
Vol 42 (4) ◽  
pp. 423 ◽  
Author(s):  
Shi-Dan Zhu ◽  
Ya-Jun Chen ◽  
Kun-Fang Cao ◽  
Qing Ye
Keyword(s):  
Water Potential ◽  
Tropical Forests ◽  
Functional Traits ◽  
Tree Species ◽  
Forest Succession ◽  
Leaf Traits ◽  
Interspecific Variation ◽  
Hydraulic Conductance ◽  
Xylem Water Potential ◽  
Sapwood Area

Plant functional traits are closely associated with plant habitats. In this study, we investigated the interspecific variations in stem and leaf hydraulics, xylem and leaf anatomy, gas-exchange rates and leaf pressure–volume relationships among three Syzygium tree species in early, mid- and late successional tropical forests. The objective was to understand the response and adaptation of congeneric species, in terms of branch and leaf functional traits, to different environments. A consistent pattern of decline with succession was evident in leaf and sapwood specific hydraulic conductivity (ks), maximum leaf hydraulic conductance (Kleaf), and photosynthetic rates for the three Syzygium species. Variations of ks and Kleaf were correlated with changes in vessel anatomy (i.e. vessel density and diameter) and leaf flux-related structure (i.e. stomatal pore index and vein density) respectively. However, specific leaf area and leaf to sapwood area ratio did not significantly differ among the three species. In addition, the mid-successional species had the lowest values of leaf water potential at full turgor and turgor loss point and 50% loss of Kleaf, but the greatest value of xylem water potential at 50% loss of ks. Our results demonstrate that leaf and branch traits associated with photosynthesis and/or hydraulic conductance, rather than those associated with drought tolerance, are the key factors underlying the response and adaptation of the three Syzygium tree species along the tropical forest succession.

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