Reassessment of Semecarpus calcicola

Kochummen - a narrow range endemic tree from

Sabah, Malaysia

Sandy T.L. Tsen , Loke Thian Yew , Aida Nabihah M Khatta , Normah Awang Besar , Zaleha Aziz ,

Richard B Sebastian , Syahrir Mhd Hatta , Suzika Juiling , Eyen Khoo , Sasikumar Tanggaraju ,

Kaden D Ashdown , Hoo Pui Kiat , Rimi Repin , Floriosha Landa , Colin R Maycock

‡ Forest Research Center, Sabah Forestry Department, Sandakan, Malaysia

§ Faculty of Tropical Forestry, Universiti Malaysia Sabah, Kota Kinabalu, Malaysia

| Faculty of Science and Natural Resources, Universiti Malaysia Sabah, Kota Kinabalu, Malaysia

¶ Forest Research Center, Sabah Foresty Department, Sandakan, Malaysia

# Oregon State University, Oregon, United States of America

¤ Sabah Parks, Kota Kinabalu, Malaysia

Corresponding author: Colin R Maycock (sepilokdata@gmail.com)

Abstract

Background

Desk-top based IUCN Red List assessment are an important first step in the conservation

of tropical trees, as they can serve as a guide for conservation action. However, field

validation is required to ensure that the limited resources available for plant conservation in

the tropics are being used effectively. The aim of this study is to conduct a field validation

of Semecarpus calcicola, a narrow range endemic tree from Sabah, Malaysia. S. calcicola

was previously known only from the type specimen collected in 1979 from Pulau

Mantanani Besar, Sabah, Malaysia. In a desk top assessment conducted in 2019, the

species was assessed as Vulnerable D2 due to a restricted range and possible threats

from land use change and natural disasters (Damit et al. 2019). During the Pulau

Mantanani Scientific Expedition in August 2019 and September 2020, surveys were carried

out on the three islands that comprise the Mantanani Islands group. Transect surveys and

plots were established to obtain information on the extent of occurrence (EOO), area of

occupancy (AOO) and an estimate of the number of mature individuals. We also assessed

the immediate and potential threats to the species.

New information

In this paper, we present new occurrences for Semecarpus calcicola, extending its

geographic range to a new island (Pulau Mantanani Kecil), and to a new substrate type

‡,§ § § § |

§ § § ¶ §

# § ¤ | §

©.

(calcareous sand deposits). We determined a revised area of occupancy (AOO) and extent

of occurrence (EOO) of 16 km for the species, and estimated the total number of mature

individuals to be below 1000 individuals. The largest subpopulation is located on Pulau

Mantanani Besar, and accounts for more than 90% of the mature individuals. Habitat loss

and degradation due to clearing of the low-lying areas for resort development and small-

scale agriculture on the limestone hills are the major threats to the population on Pulau

Mantanani Besar. While the population on Pulau Mantanni Kecil is within a gazetted

Bird Santuary, there was evidence of past small-scale agriculture. Based on these

threats, 3 locations were defined and the species reassessed as Endangered

B1ab(i,ii,iii,iv,v)+B2ab(i,ii,iii,iv,v); C2a(i,ii).

Introduction

The Post-2020 Global Biodiversity Framework calls for a reduction in the number of

threatened species and an increase in the abundance of species by 2050 (Secretariat of

the Convention on Biological Diversity 2020). While there is debate on the wording of this

goal and how it will be achieved (Williams et al. 2020), it dictates the need for accurate

assessments of the conservation status of the flora and fauna. The IUCN Red List of

Threatened Species is the primary sources of this information (Rodrigues et al. 2006). The

Red List is a useful tool for conservation planning as it allows for the identification of

species most at risk of extinction and the prioritization of conservation efforts (Rondinini et

al. 2014, Betts et al. 2020). However, to maximise the benefit accrued; the

assessments need to accurately reflect the species threat status. Within most biodiversity-

rich tropical countries, Red List assessments are typically a desk-top analysis of the

available data with input from experts. While these assessments are a good starting point,

there is a need for field validation, especially for species with traits that make them more

prone to extinction (Nic Lughadha et al. 2020, Duncan et al. 2021). Species range is one of

the major contributors to extinction risk (O'Grady et al. 2004), with narrow range endemics

generally facing a greater risk of extinction, than more widely spread species (Nic

Lughadha et al. 2020).

In a recent assessment of the 289 tree species endemic to the Malaysian State of Sabah,

73 species were recorded from a single locality (Tsen et al, unpublished data). All of these

species either fell within a threat category (65 species) or were categorized as data

deficient (8 species), and represent high priority candidates for field validation (Brummitt et

al. 2015, Bland et al. 2017). In this paper, we present a field validation of Semecarpus

calcicola, a narrow range endemic known only from the type locality on Pulau Mantanani

Besar (Large Mantanani Island) in Sabah, Malaysia.

Methods

Surveys were conducted across Pulau Mantanani Besar, Pulau Mantanani Kecil (Small

Mantanani Island) and Pulau Lingisan during the Pulau Mantanani Scientific Expedition in

August 2019 and September 2020. We determined the species distribution by mapping

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individuals encountered along transects on the Island’s network of trails, the ridge tops of

the limestone hills and transects crossing the islands. The location of the individuals

encountered were recorded using a Garmin GPSMAP 64csx. The extent of occurrence and

area of occupancy were calculated from the GPS coordinates using Geospatial

Conservation Assessment Web Tool GeoCAT (Bachman et al. 2011). The AOO was

calculated using a 4 km grid cell. To estimate the number of mature individuals, we

combined the data from the surveys with plot-based sampling. The plot-based sampling

was restricted to a 26.5 ha area that covered the limestone hills and adjacent low-lying

areas of Pulau Mantanani Besar (Fig 1). This is the recorded habitat of Semecarpus

calcicola (Kochummen 1996) and our initial surveys in August 2019 indicated it had the

greatest abundance of Semecarpus calcicola. In this area, we installed twenty-six 400 m

plots at randomly selected coordinates. All Semecarpus calcicola were enumerated, and

inspected for signs of flowering or fruiting. From these observations, we obtained a

minimum flowering diameter of 9.8 cm dbh and classified all trees greater than that as

potential mature individuals. To estimate the number of mature individuals, we used the

direct counts from the transects (excluding those within the 26.5 ha sampling area) and

extrapolation from the twenty-six 400 m plots (Loke et al. unpublished data). The species

was assigned to a Red List category based on the EOO, AOO and the estimated number

of mature individuals following the guidelines for using the IUCN Red List Categories and

Criteria (IUCN Standards and Petitions Committee 2019).

Species Conservation Profile

Semecarpus calcicola Kochummen

Species information

Taxonomy

Kingdom Phylum Class Order Family

Plantae Tracheophyta Rosids Sapindales Anacardiaceae

Taxonomic notes

This species was described by K.M Kochummen in 1996 during his revision of the

Anacardiaceae for Tree Flora of Sabah and Sarawak. The species name was initially

published using a male suffix as Semecarpus calcicolus (Kochummen 1996) and the

species is currently listed under this name on the IUCN Red List (Damit et al. 2019).

However, it has been changed to the feminine form Semecarpus calcicola on the

International Plant Names Index (IPNI 2021), as tree names are typically treated as

feminine (Manara 1991). The type specimen was collected in 1979 by Dewol Sundaling

& Awang Rahman (SAN 90206, Holotype: SAN herbarium) from Pulau Mantanani Besar

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Map of records (image):

Map of records (Google Earth):

Basis of EOO and AOO:

Min Elevation/Depth (m):

Max Elevation/Depth (m):

near Kota Belud, Sabah, Malaysia (Kochummen 1996). Kochummen (1996) distinguished

this species from the morphological similar species S. angulatus and S. cupularis based on

the inflorescence and habitat preference. S. calcicola has an extra axillary inflorescence,

with the other species having either a terminal or axillary inflorescences. Furthermore, S.

calcicola appeared to be a limestone specialist, being restricted to limestone hills of Pulau

Mantanani Besar.

Region for assessment:

- Global

Reviewers

To be determined

Editor

To be determine

Geographic range

Biogeographic realm:

- Indomalayan

Countries:

- Malaysia

Fig. 1

Suppl. material 1

Observed

Basis (narrative)

The EOO and AOO is based on GPS coordinate taken during the Pulau Mantanani

Scientific Expedition in August 2019 and September 2020.

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EOO (km2):

Trend:

Causes ceased?:

Causes understood?:

Causes reversible?:

AOO (km2):

Trend:

Causes ceased?:

Causes understood?:

Causes reversible?:

Number of locations:

Range description

Semecarpus calcicola is a narrow range endemic tree restricted to the Mantanani Island

group. The species was originally collected from the limestone hills on Pulau Mantanani

Besar in 1979, since then no other collections were made. In the recent Pulau Mantanani

Scientific Expedition organized by Sabah Parks in 2019 and 2020, the species was

recorded from the small limestone hills of Pulau Mantanani Kecil and the calcareous sand

deposits on Pulau Mantanani Besar (Fig. 2).

Extent of occurrence

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Decline (observed)

Justification for trend

Pulau Mantanani Besar has experienced an approximate 46% loss in forest cover. Forest

cover loss is continuing as a result of tourism development and land use change.

No

Yes

No

Area of occupancy

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Decline (observed)

Justification for trend

Pulau Mantanani Besar has experienced an approximate 46% loss in forest cover. There is

a continued decline in forest cover on Palau Mantanani Besar and ongoing land use

change will result in habitat degradation.

No

Yes

No

Locations

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5

Trend:

Number of individuals:

Trend:

Basis for decline:

Causes ceased?:

Causes understood?:

Causes reversible?:

Justification for number of locations

The number of locations was calculated to be three considering the main threats to the

species, namely small-holder cultivation and fire, resort development, small scale

harvesting and introduced ungulates.

Decline (observed)

Justification for trend

There is a continuous loss of forest cover and habitat degradation on Pulau Mantanani

Besar due to human activities.

Population

less than 1000 mature individuals

Decline (observed)

Justification for trend

Direct observation of changes in population and habitat extent and quality.

- (a) direct observation

- (c) a decline in area of occupancy, extent of occurrence and/or quality of habitat

No

Yes

No

Population Information (Narrative)

Fifty-four mature individuals have been located to date, of which 90% are on Pulau

Mantanani Besar. However, based on extrapolation from twenty-six 400 m plots the

estimated population on Pulau Mantanani Besar is between 509 and 764 mature

individuals (Loke et al. unpublished data). Currently there is no control over resort

development and the increasing number of resorts being established threatens the

population in the low-lying areas. There is also evidence of small-scale harvesting of

mature individuals across Pulau Mantanani Besar and small holder cultivation on the

limestone hills of both islands (Fig. 3). Seedling recruitment was high immediately after

fruiting, however, there was evidence of high rates of seedling herbivore (Fig. 4).

Subpopulations

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Abundance largest subpopulation:

Number of subpopulations:

Trend:

Severe fragmentation?:

System:

Habitat specialist:

Trend in extent, area or quality?:

Habitat importance:

Habitats:

Habitat importance:

Habitats:

Habitat importance:

Habitats:

~90% of individuals are on Pulau Mantanani Besar

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Stable

Yes

Justification for fragmentation

The two subpopulations are found on seperate islands.

Habitat

Terrestrial

Yes

Habitat (narrative)

The population is found on the limestone derived soils and calcareous sand deposits of

Pulau Mantanani Besar and Pulau Mantanani Kecil. Most of the individuals occur on the

Gomantong soil association found on the limestone hills in the eastern part of

Pulau Mantanani Besar and to a lesser extent on Pulau Mantanani Kecil. Scatter

individuals were encountered on the Usukan soil association of Pulau Mantanani Besar.

The population is primarily found in the undisturbed forests, although there are some

individuals within abandoned coconut plantations and smallholder farms.

Decline (observed)

Justification for trend

There is a continued loss of forest cover on Pulau Mantanani Besar.

Major Importance

- 1.6. Forest - Subtropical/Tropical Moist Lowland

Marginal

- 14.3. Artificial/Terrestrial - Plantations

Marginal

- 14.4. Artificial/Terrestrial - Rural Gardens

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Generation length (yr):

Dependency of single sp?:

Threat type:

Threats:

Threat type:

Threats:

Threat type:

Threats:

Ecology

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No

Ecology and traits (narrative)

Semecarpus calcicola is a small tree that reaches a maximum of about 18 m in height and

30 cm dbh. While the species is encountered on both the calcareous sand deposits and

limestone derived soils, it shows a preference for the ridges of the limestone areas (Loke et

al. unpublished data). Fruiting was observed in August 2019 and September 2020, on

individuals greater than 10 cm dbh.

Threats

Past

- 1.3. Residential & commercial development - Tourism & recreation areas

- 2.1. Agriculture & aquaculture - Annual & perennial non-timber crops

Ongoing

- 1.3. Residential & commercial development - Tourism & recreation areas

- 2.1. Agriculture & aquaculture - Annual & perennial non-timber crops

- 2.3. Agriculture & aquaculture - Livestock farming & ranching

- 5.3. Biological resource use - Logging & wood harvesting

Future

- 11.2. Climate change & severe weather - Droughts

- 11.4. Climate change & severe weather - Storms & flooding

Justification for threats

The species is threatened by habitat loss On Pulau Mantanani Besar, by the clearing of the

coastal plains for resort development and small-scale agriculture on the limestone hills.

Small-scale timber harvesting was also observed on this island. During the Pulau

Mantanani Scientific Expedition we observed abundant recruitment, however, almost all of

the recruits showed extensive herbivory damage (Fig. 4). The two likely candidates for this

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Conservation action type:

Conservation actions:

Conservation action type:

Conservation actions:

Use type:

Use and trade:

Ecosystem service type:

Research needed:

are the introduced domestic cattle or the terrestrial hermit crabs (Fig. 5). Further work is

required to determine the extent that this herbivory plays on seedling dynamics.

Conservation

Needed

- 1.1. Land/water protection - Site/area protection

- 2.1. Land/water management - Site/area management

- 3.4. Species management - Ex-situ conservation

- 4.3. Education & awareness - Awareness & communications

In Place

- 1.1. Land/water protection - Site/area protection

- 3.4. Species management - Ex-situ conservation

Justification for conservation actions

Currently only the small population on Pulau Mantanani Kecil has formal protection. Pulau

Mantanani Kecil is designated a Bird Sanctuary under the Sabah Land Ordinance 1960

(REF). There is a need to work with the local communities and resort owners to protect the

population on Pulau Mantanani Besar. During the Pulau Mantanani Scientific Expedition

seeds were collected from beneath four mother trees on Pulau Mantanani Besar, and a

small ex situ population has been established in the nurseries of the Faculty of Tropical

Forestry, Universiti Malaysia Sabah and the Forest Research Center, Sabah Forestry

Department. These seedlings need to be planted into suitable protected sites (Fig. 6)

Other

National

- 9. Construction or structural materials

Justification for use and trade

There is small scale local harvesting of this species for outdoor construction.

Less important

- 1.1. Research - Taxonomy

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- 1.2. Research - Population size, distribution & trends

- 1.3. Research - Life history & ecology

- 1.5. Research - Threats

- 2.2. Conservation Planning - Area-based Management Plan

- 3.1. Monitoring - Population trends

Justification for research needed

Semecarpus calcicola was described by Kochummen (1996) based on the morphological

characteristic of a single specimen, phylogenetic studies should be conducted to

validate this species. Further work is required to improve the estimates of population size

and population trend, particularly for the population on Pulau Mantanani Besar that faces

multiple threats. There is a need to work with the local community and resort owners to

develop a conservation management plan for this species, as continued resort

development, harvesting of mature individuals and clearing for small-scale agriculture

threatens this species.

Conclusion

Accurate assessment of the conservation status of species is crucial to facilitate

conservation actions and address the targets set in the Post 2020 Global Biodiversity

Framework. Within biodiversity-rich countries, the data on which to base these

assessments is sorely lacking for most plants and most assessments are based on a desk

review of past collection records (Prance et al. 2000). One of the shortfalls of relying on

past records is that there is the possibility that the threat category for the species will be

misassigned. Despite that, desktop assessments are a useful starting point to generate

a short list of candidate species for field validation. While field validation is both costly and

time-consuming it is essential to confirm that the status assigned accurately portrays the

situation on the ground and yields information that enable the development of species-

specific conservation actions. In the case of Semecarpus calcicola, the action

required involves a strengthening of existing protection on Pulau Mantanani Kecil, the

development of effective in situ conservation measures for the population on Pulau

Mantanani Besar and the establishment of a genetically diverse ex situ collection.

Acknowledgements

This work was conducted as part of Pulau Mantanani Expeditions organised by Sabah

Parks, we thank the director of Sabah Parks and staff for their support. We appreciate the

financial support provided by Universiti Malaysia Sabah through research grant

SDK0055-2018: Propagation and Conservation of Selected Threatened and Endangered

Species in Sabah.

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Figure 1.

Map showing Pulau Mantanai and locations of Semecarpus calcicola

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Figure 2.

A new record of Semecarpus calcicola from the calcareous sand deposits of Pulau Mantanani

Besar.

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Figure 3.

Evidence of small-scale agriculture on Pulau Mantanani Kecil

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Figure 4.

New recruit of Semecarpus calcicola showing herbivory.

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Figure 5.

Terrestrial hermit crab (Coenobita sp.) on a Semecarpus calcicola seedling.

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Figure 6.

Semecarpus calcicola seedling ready for planting at the Forest Research Centre, Sabah

Forestry Department.

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Brief description:

Supplementary material

Suppl. material 1: Fig S1. Distribution of Semecarpus calcicola and GeoCAT analysis

Authors: Tsen et al.

Data type: occurrences

The output from GeoCAT showing the AOO, EOO and distribution of

Semecarpus calcicola across the Pulau Mantanani island chain.

Download file (477.25 kb)

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