Functional Traits of Trees From Dry Deciduous “Forests” of Southern India Suggest Seasonal Drought and Fire Are Important Drivers

Ratnam, Jayashree; Chengappa, Sannuvanda K.; Machado, Siddarth; Nataraj, Nandita; Osuri, Anand M.; Sankaran, Mahesh

doi:10.3389/fevo.2019.00008

Cited by 33 publications

(33 citation statements)

References 38 publications

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“…These patterns are in line with the functional equilibrium hypothesis and confirm previous studies on above‐ground trait differences between savanna and forest species (e.g. Veenendaal et al , ; Hoffmann & Franco, ; Poorter et al , ; Ratnam et al , ). These patterns also translate to root biomass investment (RMF), where species in the closed or closing canopy forest clusters allocate less biomass to roots than the species in the open canopy savanna clusters (Fig.…”

Section: Discussionsupporting

confidence: 91%

On the importance of root traits in seedlings of tropical tree species

et al. 2020

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Plant biomass allocation may be optimized to acquire and conserve resources. How tradeoffs in the allocation of tropical tree seedlings depend on different stressors remains poorly understood. Here we test whether above-and below-ground traits of tropical tree seedlings could explain observed occurrence along gradients of resources (light, water) and defoliation (fire, herbivory).We grew 24 tree species occurring in five African vegetation types, varying from dry savanna to moist forest, in a glasshouse for 6 months, and measured traits associated with biomass allocation.Classification based on above-ground traits resulted in clusters representing savanna and forest species, with low and high shoot investment, respectively. Classification based on root traits resulted in four clusters representing dry savanna, humid savanna, dry forest and moist forest, characterized by a deep mean rooting depth, root starch investment, high specific root length in deeper soil layers, and high specific root length in the top soil layer, respectively.In conclusion, tree seedlings in this study show root trait syndromes, which vary along gradients of resources and defoliation: seedlings from dry areas invest in deep roots, seedlings from shaded environments optimize shoot investment, and seedlings experiencing frequent defoliation store resources in the roots.156 New Phytologist (2020) 227: 156-167

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Section: Discussionsupporting

confidence: 91%

On the importance of root traits in seedlings of tropical tree species

et al. 2020

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“…, Ratnam et al. ). Genus‐level average wood densities were used in the absence of species‐level estimates (Chave et al.…”

Section: Methodsmentioning

confidence: 99%

Effects of restoration on tree communities and carbon storage in rainforest fragments of the Western Ghats, India

et al. 2019

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Ecological restoration is a leading strategy for reversing biodiversity losses and enhancing terrestrial carbon sequestration in degraded tropical forests. There have been few comprehensive assessments of recovery following restoration in fragmented forest landscapes, and the efficacy of active versus passive (i.e., natural regeneration) restoration remains unclear. We examined 11 indicators of forest structure, tree diversity and composition (adult and sapling), and aboveground carbon storage in 25 pairs of actively restored (AR; 7–15 yr after weed removal and mixed‐native tree species planting) and naturally regenerating (NR) plots within degraded rainforest fragments, and in 17 less‐disturbed benchmark (BM) rainforest plots in the Western Ghats, India. We assessed the effects of active restoration on the 11 indicators and tested the hypothesis that the effects of active restoration increase with isolation from contiguous and relatively intact rainforests. Active restoration significantly increased canopy cover, adult tree and sapling density, adult and sapling species density (overall and late‐successional), compositional similarity to benchmarks, and aboveground carbon storage, which recovered 14–82% toward BM targets relative to NR baselines. By contrast, tree height–diameter ratios and the proportion of native saplings did not recover consistently in actively restored forests. The effects of active restoration on canopy cover, species density (adult), late‐successional species density (adult and sapling), and species composition, but not carbon storage, increased with isolation across the fragmented landscape. Our findings show that active restoration can promote recovery of forest structure, composition, and carbon storage within 7–15 yr of restoration in degraded tropical rainforest fragments, although the benefits of active over passive restoration across fragmented landscapes would depend on indicator type and may increase with site isolation. These findings on early stages of recovery suggest that active restoration in ubiquitous fragmented landscapes of the tropics could complement passive restoration of degraded forests in less fragmented landscapes, and protection of intact forests, as a key strategy for conserving biodiversity and mitigating climate change.

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“…In general, drier regions are characterized by less dense forests, and exhibit lower VOD values that are distributed in a reduced range, with respect to wetter regions where rainforests occur. AGB is lower in open forests, and dry forest types are known to have lower height, diameter ratios, lower specific leaf areas, higher wood densities, and higher relative bark thickness, than evergreen forest species (Ratnam et al, 2019). Thus, the sparser canopy coverage plus these specific traits cause a lower VOD response in drier areas.…”

Section: Discussionmentioning

confidence: 99%

“…Thus, the high correlation values observed for GPP max , LUE, and then WUE, can be attributed to VOD sensitivity to biomass which is related to forestand water-related attributes. Instead, the BW measurements derived with eddy covariance techniques are known to be prone to uncertainty over forested lands, due to low wind speed over forests and the resulting occasional stalling of anemometers (Spittlehouse & Black, 1980 forest types are known to have lower height, diameter ratios, lower specific leaf areas, higher wood densities, and higher relative bark thickness, than evergreen forest species (Ratnam et al, 2019). Thus, the sparser canopy coverage plus these specific traits cause a lower VOD response in drier areas.…”

Section: Spatial Correlations and Gpp Max And Lue Retrievalmentioning

confidence: 99%

Monitoring tropical forests under a functional perspective with satellite‐based vegetation optical depth

Laurin

Vittucci

Tramontana

et al. 2020

Global Change Biology

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Monitoring ecosystem functions in forests is a priority in a climate change scenario, as climate‐induced events may initially alter the functions more than slow‐changing attributes, such as biomass. The ecosystem functional properties (EFPs) are quantities that characterize key ecosystem processes. They can be derived by point observations of gas and energy exchanges between the ecosystems and the atmosphere that are collected globally at FLUXNET flux tower sites and upscaled at ecosystem level. The properties here considered describe the ability of ecosystems to optimize the use of resources for carbon uptake. They represent functional forest information, are dependent on environmental drivers, linked to leaf traits and forest structure, and influenced by climate change effects. The ability of vegetation optical depth (VOD) to provide forest functional information is investigated using 2011–2014 satellite data collected by the Soil Moisture and Ocean Salinity mission and using the EFPs as reference dataset. Tropical forests in Africa and South America were analyzed, also according to ecological homogeneous units. VOD jointly with water deficit information explained 93% and 87% of the yearly variability in both flux upscaled maximum gross primary productivity and light use efficiency functional properties, in Africa and South America forests respectively. Maps of the retrieved properties evidenced changes in forest functional responses linked to anomalous climate‐induced events during the study period. The findings indicate that VOD can support the flux upscaling process in the tropical range, affected by high uncertainty, and the detection of forest anomalous functional responses. Preliminary temporal analysis of VOD and EFP signals showed fine‐grained variability in periodicity, in signal dephasing, and in the strength of the relationships. In selected drier forest types, these satellite data could also support the monitoring of functional dynamics.

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Functional Traits of Trees From Dry Deciduous “Forests” of Southern India Suggest Seasonal Drought and Fire Are Important Drivers

Cited by 33 publications

References 38 publications

On the importance of root traits in seedlings of tropical tree species

On the importance of root traits in seedlings of tropical tree species

Effects of restoration on tree communities and carbon storage in rainforest fragments of the Western Ghats, India

Monitoring tropical forests under a functional perspective with satellite‐based vegetation optical depth

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