Soil-induced impacts on forest structure drive coarse woody debris stocks across central Amazonia

Martins, D.; Schietti, Juliana; Feldpausch, Ted R.; Luizão, Flávio J.; Phillips, Oliver L.; Andrade, Ana; Castilho, Carolina V.; Laurance, Susan G.; Oliveira, Átila Cristina Alves de; Amaral, Iêda Leão do; Toledo, José Júlio de; Lugli, Laynara F.; Pinto, J. L. P. V.; Mendoza, E.M. Oblitas; Quesada, Carlos A.

doi:10.1080/17550874.2013.879942

Cited by 24 publications

(27 citation statements)

References 46 publications

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“…Mean annual precipitation in this area varies from 2,100 to 2,700 mm (Hijmans, Cameron, Parra, Jones, & Jarvis, 2005), with on average two to three consecutive months with <100 mm rainfall (dry months) per year (Sombroek, 2001). Soils are predominantly Plinthosols and Gleysols, the predominant texture is silt to fine sand, with poor drainage, and varying degrees of soil water saturation and anoxic conditions (Martins et al, 2014;Sombroek, 2000). Soils physical structure is generally dense and restrictive to root growth, with varying degrees of hardness and effective soil depth (Quesada et al, 2010).…”

Section: Study Area and Sampling Designmentioning

confidence: 99%

“…Higher scores denote more limited soil conditions for plant roots. Soil physical classification was determined in 2 m deep pits dug in each research site and in soil-profile samples from all plots (Martins et al, 2014). As a proxy of soil fertility we used the available phosphorus content (extracted with Mehlich-1; EMBRAPA, 2011) determined from a compound sample derived from six subsamples from the first 30 cm soil depth (Schietti et al, 2016).…”

Section: Environmental Datamentioning

confidence: 99%

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Palms and trees resist extreme drought in Amazon forests with shallow water tables

et al. 2020

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The intensity and frequency of severe droughts in the Amazon region have increased in the recent decades. These extreme events are associated with changes in forest dynamics, biomass and floristic composition. However, most studies of drought response have focused on upland forests with deep water tables, which may be especially sensitive to drought. Palms, which tend to dominate the less well‐drained soils, have also been neglected. The relative neglect of shallow water tables and palms is a significant concern for our understanding of tropical drought impacts, especially as one‐third of Amazon forests grow on shallow water tables (<5 m deep). We evaluated the drought response of palms and trees in forests distributed over a 600 km transect in central‐southern Amazonia, where the landscape is dominated by shallow water table forests (SWTF). We compared vegetation dynamics before and following the 2015–2016 El Nino drought, the hottest and driest on record for the region (−214 mm of cumulative water deficit). We observed no change in stand mortality rates and no biomass loss in response to drought in these forests. Instead, we observed an increase in recruitment rates, which doubled to 6.78% year‐1 ± 4.40 (M ± SD) during 2015–2016 for palms and increased by half for trees (to 2.92% year‐1 ± 1.21), compared to rates in the pre‐El‐Nino interval. Within these SWTF, mortality and recruitment rates varied as a function of climatic drought intensity and water table depth for both palms and trees, with mortality being greatest in climatically and hydrologically wetter environments and recruitment greatest in drier environments. Across our transect, there was a significant increase over time in tree biomass. Synthesis. Our results indicate that forests growing over shallow water tables—relatively under‐studied vegetation that nonetheless occupies one‐third of Amazon forests—are remarkably resistant to drought. These findings are consistent with the hypothesis that local hydrology and its interactions with climate strongly constrain forest drought effects, and has implications for climate change feedbacks. This work enhances our understanding of integrated drought effects on tropical forest dynamics and highlights the importance of incorporating neglected forest types into both the modelling of forest climate responses and into public decisions about priorities for conservation.

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Section: Study Area and Sampling Designmentioning

confidence: 99%

Section: Environmental Datamentioning

confidence: 99%

Palms and trees resist extreme drought in Amazon forests with shallow water tables

et al. 2020

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“…Two classes of models have been used for CDW estimation using lidar: (1) area-based models estimate CDW indirectly based on lidar metrics calibrated with data from forest inventory plots (Martinuzzi et al, 2009;Pesonen et al, 2008), and (2) individual-based models identify standing dead trees . Wall-to-wall maps and histograms of total CDW predicted by lidar-only models at landscape level (166 m resolution).…”

Section: Comparisons To Other Lidar-related Modelsmentioning

confidence: 99%

Estimation of coarse dead wood stocks in intact and degraded forests in the Brazilian Amazon using airborne lidar

et al. 2019

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Coarse dead wood is an important component of forest carbon stocks, but it is rarely measured in Amazon forests and is typically excluded from regional forest carbon budgets. Our study is based on line intercept sampling for fallen coarse dead wood conducted along 103 transects with a total length of 48 km matched with forest inventory plots where standing coarse dead wood was measured in the footprints of larger areas of airborne lidar acquisitions. We developed models to relate lidar metrics and Landsat time series variables to coarse dead wood stocks for intact, logged, burned, or logged and burned forests. Canopy characteristics such as gap area produced significant individual relations for logged forests. For total fallen plus standing coarse dead wood (hereafter defined as total coarse dead wood), the relative root mean square error for models with only lidar metrics ranged from 33 % in logged forest to up to 36 % in burned forests. The addition of historical information improved model performance slightly for intact forests (31 % against 35 % relative root mean square error), not justifying the use of a number of disturbance events from historical satellite images (Landsat) with airborne lidar data. Lidarderived estimates of total coarse dead wood compared favorably with independent ground-based sampling for areas up to several hundred hectares. The relations found between total coarse dead wood and variables quantifying forest structure derived from airborne lidar highlight the opportunity to quantify this important but rarely measured component of forest carbon over large areas in tropical forests.

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“…At this scale, there is a significant positive relationship between aboveground live biomass and necromass stock (Chao et al 2009). However, an extensive survey of necromass on a northsouth transect from the Manaus area to Humaitá found no relation to aboveground live biomass, differences in necromass stocks being explained instead by soil quality and other limitations on site quality for tree growth (Martins et al 2014). In a pantropical review, Palace et al (2012) found that undisturbed forests had a peak of b Fig.…”

Section: Necromass (Dead Biomass)mentioning

confidence: 99%

Brazil’s Amazonian forest carbon: the key to Southern Amazonia’s significance for global climate

Fearnside

2016

Reg Environ Change

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Southern Amazonia is the first region of Brazil's Amazon area to be exposed to intensive conversion to agriculture and ranching. This conversion emits greenhouse gases from the carbon stock in the biomass and soils of the previous vegetation. Quantifying these carbon stocks is the first step in quantifying the impact on global warming from this conversion. This review is limited to information on Brazilian Amazonia's carbon stocks. It indicates large amounts of carbon at risk of emission in both biomass and soils, as well as considerable uncertainty in estimates. Reducing uncertainty is a priority for research but the existence of uncertainty must not be used as an excuse for delaying measures to contain deforestation. The magnitude of carbon stocks is proportional to greenhouse gas emissions per hectare of deforestation and consequently to impact on global climate.

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Soil-induced impacts on forest structure drive coarse woody debris stocks across central Amazonia

Abstract: Background: Coarse woody debris (CWD) is an essential component in tropical forest ecosystems and its quantity varies widely with forest types.

Cited by 24 publications

References 46 publications

Palms and trees resist extreme drought in Amazon forests with shallow water tables

Palms and trees resist extreme drought in Amazon forests with shallow water tables

Estimation of coarse dead wood stocks in intact and degraded forests in the Brazilian Amazon using airborne lidar

Brazil’s Amazonian forest carbon: the key to Southern Amazonia’s significance for global climate

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