Ground surface microtopography and vegetation patterns in a tropical peat swamp forest

Lampela, Maija; Jauhiainen, Jyrki; Kämäri, Iida; Koskinen, Markku; Tanhuanpää, Topi; Valkeapää, Annukka; Vasander, Harri

doi:10.1016/j.catena.2015.12.016

Cited by 66 publications

(69 citation statements)

References 22 publications

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“…The hummocks consist of partly decomposed logs, branches, and leaves lodged among living buttresses, stilt roots, pneumatophores, and giant rhizomes. Whereas the microtopography in high-latitude peat bogs may have regular and oriented patterns (21), surveys by Lampela et al (20) in a tropical peat swamp in Central Kalimantan showed no orientation or regularity. Similarly, our microtopography survey and other observations revealed no regular patterns or channels in peat dome microtopography.…”

Section: Methodsmentioning

confidence: 99%

“…At high water tables, hollows become flooded from saturation of the peat below, forming small pools. These pools are not connected into channels (20) and therefore do not allow open-channel flow on a large scale in the peatland. Instead, flow through the peatland is limited by flow through the porous matrix of the hummocks between these isolated pools.…”

Section: Methodsmentioning

confidence: 99%

“…Superimposed on the gross morphology of a peat dome is a fine microtopography of meter-scale depressions, or hollows, separated by higher areas, or hummocks (19,20). The hummocks consist of partly decomposed logs, branches, and leaves lodged among living buttresses, stilt roots, pneumatophores, and giant rhizomes.…”

Section: Methodsmentioning

confidence: 99%

“…We refer to this reference surface p as the land surface. The peat surfacep is a "texture" that sits on the smooth land surface p. The bottoms of hollows provide the most readily identifiable local reference elevation (20), so we define the land surface p as a smooth surface fit through the bottoms of hollows (local minima in the peat surfacep). On the basis of this definition, we determined the current land surface at our site by smoothing a raster map obtained from local minima in LiDAR lastreturn points.…”

Section: Methodsmentioning

confidence: 99%

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How temporal patterns in rainfall determine the geomorphology and carbon fluxes of tropical peatlands

Cobb

Hoyt

Gandois

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

111

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Tropical peatlands now emit hundreds of megatons of carbon dioxide per year because of human disruption of the feedbacks that link peat accumulation and groundwater hydrology. However, no quantitative theory has existed for how patterns of carbon storage and release accompanying growth and subsidence of tropical peatlands are affected by climate and disturbance. Using comprehensive data from a pristine peatland in Brunei Darussalam, we show how rainfall and groundwater flow determine a shape parameter (the Laplacian of the peat surface elevation) that specifies, under a given rainfall regime, the ultimate, stable morphology, and hence carbon storage, of a tropical peatland within a network of rivers or canals. We find that peatlands reach their ultimate shape first at the edges of peat domes where they are bounded by rivers, so that the rate of carbon uptake accompanying their growth is proportional to the area of the still-growing dome interior. We use this model to study how tropical peatland carbon storage and fluxes are controlled by changes in climate, sea level, and drainage networks. We find that fluctuations in net precipitation on timescales from hours to years can reduce long-term peat accumulation. Our mathematical and numerical models can be used to predict long-term effects of changes in temporal rainfall patterns and drainage networks on tropical peatland geomorphology and carbon storage.tropical peatlands | peatland geomorphology | peatland hydrology | peatland carbon storage | climate-carbon cycle feedbacks T ropical peatlands store gigatons of carbon in peat domes, gently mounded land forms kilometers across and 10 or more meters high (1). The carbon stored as peat in these domes has been sequestered by photosynthesis of peat swamp trees (2) and preserved for thousands of years by waterlogging, which suppresses decomposition. Human disturbance of tropical peatlands by fire and drainage for agriculture is now causing reemission of that carbon at rates of hundreds of megatons per year (2-5): Emissions from Southeast Asian peatlands alone are equivalent to about 2% of global fossil fuel emissions or 20% of global land use and land cover change emissions (6, 7). Because peat is mostly organic carbon, a description of the growth and subsidence of tropical peatlands also quantifies fluxes of carbon dioxide (1,4,8). Evidence from a range of studies establishes that accumulation and loss of tropical peat are controlled by water table dynamics (4, 9). When the water table is low, aerobic decomposition occurs, releasing carbon dioxide; when the water table is high, aerobic decomposition is inhibited by lack of oxygen, production of peat exceeds its decay, and peat accumulates. In this way, the rate of peat accumulation is determined by the fraction of time that peat is exposed by a low water table (Fig. 1).The water table rises and falls in a peatland according to the balance between rainfall, evapotranspiration, and groundwater flow. Water flows downslope toward the edge of each peat dome, where it is bo...

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

How temporal patterns in rainfall determine the geomorphology and carbon fluxes of tropical peatlands

Cobb

Hoyt

Gandois

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

111

View full text Add to dashboard Cite

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“…In TPSFs, the forest floor surface is highly variable, comprised of a mosaic of hummocks and hollows, which co‐occur within the space of just a few meters (Lampela et al . , Fig. S1).…”

mentioning

confidence: 97%

Microtopographic specialization and flexibility in tropical peat swamp forest tree species

et al. 2017

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Tropical tree species distributions are determined by a wide range of biotic and abiotic factors, including topography and hydrology. Tropical peat swamp forests (TPSFs) are characterized in part by small‐scale variations in topography (‘hummocks’ and ‘hollows’) that create distinct microhabitats and thus may contribute to niche diversification among TPSF tree species. Using tree elevations calibrated to daily peat water levels collected using a data logger and a permutation test, we evaluated topographical microhabitat preferences for 21 tree species in a relatively undisturbed TPSF in Central Kalimantan, Indonesia, to determine whether these species show preferential association with hummocks or hollows and to quantify the prevalence of microhabitat specialization among them. Only one species, Tetractomia tetrandrum, emerged as a hollow specialist, with no hummock specialists among the species tested. The remaining 20 species, including Psydrax dicoccos, which had the lowest mean observed elevation, and Maasia hypoleuca, which had the highest mean observed elevation, showed no clear microtopographic preference. This suggests that many TPSF species may be resilient to the natural hydrologic variations that occur in relatively intact peat swamp forests. Such studies of microtopographic preferences of tree species in TPSF and other wetland forest ecosystems can inform selection of tree species for reforestation projects, and potentially also provide information on how future climate change may impact these habitats and their resident tree species.

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Tropical peatland hydrology simulated with a global land surface model

Apers¹,

Lannoy²,

Baird³

et al. 2021

Preprint

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Tropical peatlands are among the most carbon-dense ecosystems on Earth, and their water storage dynamics strongly control these carbon stocks. The hydrological functioning of tropical peatlands differs from that of northern peatlands, which has not yet been accounted for in global land surface models (LSMs). Here, we integrated tropical peat-specific hydrology modules into a global LSM for the first time, by utilizing the peatland-specific model structure adaptation (PEATCLSM) of the NASA Catchment Land Surface Model (CLSM). We developed literature-based parameter sets for natural (PEATCLSM Trop,Nat ) and drained (PEATCLSM Trop,Drain ) tropical peatlands. Simulations with PEATCLSM Trop,Nat were compared against those with the default CLSM version and the northern version of PEATCLSM (PEATCLSM North,Nat ) with tropical vegetation input. All simulations were forced with global meteorological reanalysis input data for the major tropical peatland regions in Central and South America, the Congo Basin, and Southeast Asia. The evaluation against a unique and extensive data set of in situ water level and eddy covariance-derived evapotranspiration showed an overall improvement in bias and correlation compared to the default CLSM version. Over Southeast Asia, an additional simulation with PEATCLSM Trop,Drain was run to address the large fraction of drained tropical peatlands in this region. PEATCLSM Trop,Drain outperformed CLSM, PEATCLSM North,Nat , and PEATCLSM Trop,Nat over drained sites. Despite the overall improvements of PEATCLSM Trop,Nat over CLSM, there are strong differences in performance between the three study regions. We attribute these performance differences to regional differences in accuracy of meteorological forcing data, and differences in peatland hydrologic response that are not yet captured by our model. Plain Language SummaryTropical peatlands are wetlands in which plant material accumulates under waterlogged conditions and develops into a dense organic soil layer. Disturbance of their selfregulating hydrology by external factors such as artificial drainage, land use change, and climate change can quickly convert these immense carbon stocks into strong sources of greenhouse gases. Including the hydrology of tropical peatlands into global Earth system models allows us to understand the impact of such external disturbances. We developed the first hydrology modules for natural and drained tropical peatlands to plug into the NASA Goddard Earth Observing System modeling framework. Our results display strong regional differences, and indicate that the accuracy of our model is limited by rainfall data quality and by our understanding of how peatland hydrology differs across the three regions that contain the major tropical peatland areas (Central and South America, the Congo Basin, and Southeast Asia). Nonetheless, simulations

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Ground surface microtopography and vegetation patterns in a tropical peat swamp forest

Cited by 66 publications

References 22 publications

How temporal patterns in rainfall determine the geomorphology and carbon fluxes of tropical peatlands

How temporal patterns in rainfall determine the geomorphology and carbon fluxes of tropical peatlands

Microtopographic specialization and flexibility in tropical peat swamp forest tree species

Tropical peatland hydrology simulated with a global land surface model

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