Central dry evergreen riparian forest

အလယ်ပိုင်း ခြောက်သွေ့ အမြဲစိမ်း မြစ်ချောင်းကမ်းနား သစ်တောများ

Extinction Risk

NE
DD
LC
NT
VU
EN
National IUCN statusCR
CO

Climate and ecology

Realm

Freshwater/Terrestrial

Biome

Palustrine Wetlands

Functional Group

Tropical flooded forests and peat forests

Description

An evergreen forest consisting of large rainforest trees that fringe the rivers and major streams of Myanmar’s central dry zone. This ecosystem is heavily degraded and only small fragments in various states were found during our field studies. This ecosystem is likely to occur along major streams throughout the Ayeyarwady floodplain in Sagaing, Mandalay and possibly Bago. Buttressed trees are probably present in remnant vegetation (Davis, 1960), although much of these ecosystems are probably replaced now with village forests and plantings.

Distribution

Central dry evergreen riparian forest has not been mapped. However, it is likely to occur throughout the central dry zone along permanent waterways where remnant vegetation still exists. We estimated the broad extent of this ecosystem by buffering large rivers and streams (200 m) and identifying areas covered in trees. Although there is likely large error to this estimate due to including gardens and planted tree, we expect riparian forest to follow this broad distribution.

Characteristic

Native biota

Details

This ecosystem occurs above the upper limit of mangrove forests (Stamp 1925). Tree species may include Elaeocarpus hygrophilus (Elaeocarpaceae), Lagerstroemia speciosa (Lythraceae), Mangifera caloneura (Anacardiaceae), Calophyllum sp. (Calophyllaceae), Litsea nitida and Aglaia cucullata (Meliaceae). A variety of cane species may also be present (Stamp 1925). No field work was conducted in this ecosystem type, so an extensive inventory of characteristic biota has not been developed.

Abiotic environment

Mean temperature

No data

Soil

No data

Precipitation

No data

Elevation

No data

Details

This ecosystem occurs along permanent lowland waterways where there is a reliable year-round water supply. Typically, it occurs on riparian levees, where the forest is seasonally flooded during the monsoon, which occurs between May and October.

Key processes and interactions

Most species in this ecosystem are adapted to periodic flooding and frequent inundation is a key process that maintains this ecosystem. Floods transport and deposit woody debris and alluvium, promoting habitat diversity for birds and invertebrates, and replenishing soil nutrients. Floods may also create forest gaps enabling tree recruitment. Physical disturbance associated with floods can lead to changes in growth, community composition, light penetration and structure, altering the input of nutrients, organic matter and other detritus.

Major threat

Major threat

This ecosystem has been extensively cleared for agriculture, access to waterways and urban development. Likely to have been heavily cut in historical times for timber, which could be used locally or floated downstream. The remaining fragments are very small, continually disturbed by human access and flooding, which promote the invasion of introduced plant species dispersed by floodwaters from disturbed areas upstream. Exotic trees such as Samanea saman (rain tree) are also extensively planted throughout the distribution of this ecosystem type.

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

We used a broad estimate of the former distribution of riparian forest and a recently developed dataset of tree cover to infer that up to 97.4% of this ecosystem has been lost since 1750. Remaining patches of this ecosystem are very small (often single remnant trees) and ongoing urbanisation and hardening of waterways is likely to be causing ongoing declines. Critically Endangered.

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

This ecosystem is widespread with EOO and AOO not meeting category thresholds for threatened. However, an assessment of present distribution (~2016) against an assumed historical distribution that approximates the same distribution as rice- paddies today, suggests that at least 70.1% of this ecosystem has been transformed to agriculture since the 1750s. The ecosystem therefore qualifies as Endangered under Criterion A3.

Date Assessed

2021-09-25

Year published

2019

Assessed by

Nicholas Murray

Reviewed by

David Keith

Contributed by

Adam Duncan