Central Ayeyarwady Palm savanna

ဧရာဝတီအလယ်ပိုင်း ထန်းနှင့် မြက်ခင်းတော

Extinction Risk

National IUCN statusVU

Climate and ecology




Savannas And Grasslands

Functional Group

Pyric tussock savannas


An open woodland with conspicuous tall palms, Borassus flabellifer, (“Taung-on”) up to 30 m tall, and distinctively white-trunked trees of Acacia leucophloea (“Htanaung”) that grow up to 10-12 m tall occur in the driest climates of the central Myanmar plains. A ground layer comprises C4 grasses, sedges and forbs that become lush in response to monsoon rains. It co-occurs with Sha thorn scrub, which occurs on drier sites and is distinguished by the absence of palms and drier, more open ground layer vegetation. No remnant patches of this ecosystem were identified in the assessment, despite extensive field traverses, only relic trees and small plantations were observed.


Although this ecosystem has never been mapped, fieldwork by the authors suggest that it was restricted to the central dry zone.


Native biota


There is very little information on the native plants and animals of this ecosystem. Borassus flabellifer (Arecaceae), Acacia leucophloea and Acacia catechu (Fabaceae) are the dominant trees, but some stands also have broad-leaved trees. The ground layer is highly disturbed by grazing and cultivation. It is dominated by introduced plants but likely to include native hydrophytic grasses, sedges and forbs, including Paspalum, Isachne, Oryza (Poaceae), Carex, Cyperus (Cyperaceae) and Persicaria (Polygonaceae). This ecosystem once supported endemic and near-endemic birds including Burmese Collared-dove Streptopelia xanthocycla, Jerdon's Minivet Pericrocotus albifrons (NT), Hooded Treepie Crypsirina cucullate (NT) Burmese Bushlark Mirafra microptera, Burmese Prinia Prinia cooki, Ayeyarwady Bulbul Pycnonotus blanfordi and White-throated Babbler Chatarrhaea gularis. The system probably supported an assemblage of large herbivores (e.g. cervids, rhinoceros, elephants) and their predators (tigers and smaller felines).

Abiotic environment

Mean temperature

No data


Depositional and fine-textured loams


700 - 1,000 mm per annum


No data


Mean annual rainfall is 700 - 1000 mm, with a regular seasonal drought from October to late May when monsoonal rains arrive. Palm savannas occur on flat terrain in low-lying areas that remain saturated in the monsoon season and may retain shallow surface water after deluges. Temperatures are hot, with little seasonal variation. The soils are depositional and fine-textured loams. They may be deep and have an appreciable organic content.

Key processes and interactions

Rainfall gradients define the distribution of this ecosystem in the rain shadow of Myanmar’s central Ayeyarwady valley. The amount and timing of monsoonal rains determine annual flushes of productivity in ground layer vegetation. Grazing by native megafauna may have been important in the dynamics of groundlayer vegetation in historical times. Domestic cattle are now the principle herbivores. Surface movement and slow drainage

Major threat

Major threat

This ecosystem has been transformed, almost in its entirety, to dry agriculture for beans and pulses, irrigated rice paddies and grazing pastures.

Instruction: The visualization shows threats that are present within each ecosystem. According to IUCN, direct threats are the proximate human activities or processes that have impacted, are impacting, or may impact the the status of the taxon being assessed. Click of the highlighted icons to see details each threat category.

Ecosystem Assessment

Assessment Summary

The former range of this ecosystem is evident in agricultural landscapes by conspicuous palms up to 30m high (Borassus flabellifer). We found no occurrences of this ecosystem, rather only single trees scattered throughout agricultural landscapes. Overall, the palm savanna appears to have been transformed into anthropogenic ecosystems with scattered native trees and a large introduced biota, especially of exotic plants and domestic livestock. Therefore, it appears that the historical distribution of the ecosystem may have declined by 100% (Criterion A3). Collapsed.

Instruction: Click on the chart to view the detailed assessment result for each RLE risk criteria. Risk is defined as the probability of an adverse outcome over a specified time-frame. Here, the adverse outcome is the endpoint of ecosystem decline, which the RLE terms ecosystem collapse.

Ecosystem collapse definition

Central Ayeyarwady Palm Savanna is regarded as collapsed when its area has declined to 0 km2.

Date Assessed


Year published


Assessed by

Nicholas Murray,David Keith

Reviewed by

Hedley Grantham

Contributed by