DIWPA: DIVERSITAS in the Western Pacific and Asia

DIWPA News Letter
Office: Center for Ecological Research, Kyoto University, Otsu, Shiga, Japan

September
2023

No. 49Message from the Secretary General

Message from the chairperson

Shin-ichi Nakano

Atsushi Ishida

One of the main functions of DIWPA is capacity
building of scientists in particular young scientists
from developing countries. Therefore, we organize
DIWPA International Field Biology Course (IFBC)
where graduate and undergraduate students and postdocs in the Western Pacific and Asia. In the present
year 2023, we conducted IFBC in Lake Biwa and its
satellite lakes from 20 to 26 August. We made thecall-for-application to IFBC in our website
previously, and many students and post-docs applied
it. After careful review, we determined one excellent
winner student from Thailand, Ms. Pattama Jitrabiab(Pat), a Ph.D. student from Valaya Alongkorn
Rajabhat University (see Pat’s article in the present
newsletter). Besides Pat, two undergraduate students
from Kyoto University joined and learned together
aquatic ecology including basic limnology in lakes,
fundamental ecological and/or biodiversity studies onplankton, benthic invertebrates, data analyses anddatabase preparation. All the students, together with
CER staffs, enjoyed collaborating ecology, limnology
and biodiversity in those lakes. Finally, the students
gave oral presentations in English and had
discussions on what the data collected by themselvesscientifically indicated. The IFBC was quite
successful! We expect the next IFBC 2024 on forests
would also be the case in hope that you will enjoy
ecology and biodiversity together.

Due to the impact of the COVID-19 pandemic, wewere unable to hold the DIWPA Field Biology Course
for three years. However, in this summer, we inviteda doctoral student from Thailand and were able toconduct the DIWPA International Field Biology
Course at Lake Biwa in Japan. The report from thisstudent is currently published in this DIWPA
newsletter. Although the COVID-19 infections are
frequently found in Japan, our lives are gradually
returning to normal and we are seeing an increase inforeign visitors to Kyoto in Japan. We believe that wewill be able to host the DIWPA Field Biology Course
again in next year (2024). Probably, the next Field
Biology Course is conducted on forests, we will beable to inform it in 2024 on DIWPA homepage.
To examine biodiversity in the physiological
function of trees in tropical seasonally dry forests, I
collected leaf ecophysiological data in Thailand as acollaboration with DIWPA members. The analyzed
results were published in the journal "Scientific Data"on September 8, 2023. In this paper, I illuminate thevariations of leaf traits related to differences in soil
properties among the forest types. This finding
indicates the existence of a mechanism for niche
segregation among forest trees (forest types) based on
edaphic factors in soils. We store the raw data in the"Dryad Digital Repository" (Ishida et al. 2022; DOI:
10.5061/dryad.12jm63z10), for making it freely
accessible for meta-analysis and other research
purposes. I believe that the close relationship between
forests and soils offers essential insights forpredicting forest responses to future environmental
changes and for the restoration of degraded forests. I
provide more details in this DIWPA Newsletter.

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DIWPA News Letter No.49

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2023 DIWPA International Field Biology
Course in Lake Biwa
Pattama Jitrabiab
Doctoral program in Environmental Studies, College of Innovative Management
Valaya Alongkorn Rajabhat University under the Royal Patronage (Thailand)

I am currently pursuing Doctor of Philosophy
Environmental Studies Course at the College of
Innovative Management, Valaya Alongkorn
Rajabhat University under the Royal Patronage,
Thailand.
2023 DIWPA International Field Biology
Course in Lake Biwa has given me the opportunity
to learn and gain experience in water resource
ecology. This is also relevant to my Ph.D. researchon microplastic contamination in tributaries of thelower Chao Phraya River.
Professor Shi-ichi Nakano (Supervisor of
the summer program), Associate Professor Takuya
Sato, and others provided me knowledge oftheoretical studies of aquatic ecology. I also
experienced practical training in Lake Biwa, whichis the largest freshwater lake in Japan, locate in
Shiga prefecture on the island of Honshu, Japan.
This 670 square kilometer lake is an importantwater resource that supplies city and industrial
water for 13 million residents in Osaka, Kyoto andKobe megalopolis.
On the second day, we visited the offshore
area in Lake Biwa. I boarded a research vessel“Hasu” owned by Center of Ecological ResearchCenter (CER), Kyoto University (Fig. 1). I learned
how to use tools to collect samples of plankton andbenthic fauna and the CTD Profiler (theConductivity, Temperature and Depth), an
integrated instrument package designed to measure
the water column's conductivity, temperature, andpressure (depth). The instrument is lowered via

cable through the water column. It permits scientists
to observe the physical properties in real time via a
conducting cable, which is typically connected to a
CTD to a deck unit and a computer on the vessel(Figs. 2 and 3). For this study, we measured watertransparency at the depths of 11, 24 and 50 meter inthe lake using a Secchi Disk. Water samples at
depths of 11, 24, and 50 meters were taken to
determine the amount of dissolved oxygen(Dissolved Oxygen, DO) which is important for thelife of aquatic organisms. The oxygen in water was
analyzed by Winkler method using MnSO4 alkaliiodide-azide reagent. The results of analysis will becompared with the results from measuring
Dissolved Oxygen with the RINKO-Profiler.
Furthermore, we collected the plankton samples atthe surface of the water with a plankton net tool andthe benthic samples with sediment sampling

Fig. 1. A research vessel “Hasu”

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DIWPA News Letter No.49

On the last day of the training, we wereassigned the presentation to share the study results.
I gave a presentation of the topic “Relationships
between bacteria and factors affecting bacterial
abundance”. The objectives were as follows: 1) toexamine the relationship between the amount of
Dissolved Oxygen and the various depths of water,and 2) to examine the amount of Chlorophyll thevarious depths of water.
This training allowed me to gain knowledge
and experience in water ecology to be useful in mydoctoral research as well as good friendships fromthe training participants. I would like to thankProfessor Shi-ichi Nakano, Associate Professor
Takuya Sato, and everyone who helped and gave
advice to me during the training from the first day
until the last. I will never forget these memories andour friendship.

Fig. 2 & 3. A deck unit and a computer on the ship

equipment. All examples of plankton and benthic
fauna were brought back the laboratory at CER andexamined to determine their species (Fig. 4).
On the 3rd day, we visited Okishima Islandin Lake Biwa, the largest island in the lake and theonly populated island, to study the amount of
Dissolved Oxygen, DO, and environmental data in
the water body. Since the depth of water is shallow,
there was only one sampling point in vertical
distribution, and we used the mode of measuring at
1-second interval. Because the water depth wasapproximately 1 m, the measurement was conductedat the depth of approximately 0.5 m. Although
Chlorophyll-A concentration and turbidity data
were highly variable, they could not be measured
well. The diversity and abundance of plankton,
benthic fauna, and cyanobacteria collected in
Okishima Island were examined. To determine thefoods of fishes, we examined the stomach contents
with a microscope. The number of bacteria wascounted using the DAPI Fluorescent Staining
method. (Figs. 5 and 6).

Fig. 5. Collecting samples at Okishima Island

Fig. 4. Laboratory work at CER

Fig. 6. At the pier in Okishima Island

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DIWPA Collaboration:
Inventory data on the leaf ecophysiology
of canopy trees in dry evergreen and two
drought-deciduous forests in Thailand
Atsushi Ishida
Center for Ecological Research, Kyoto University (Japan)

The inventory data on leaf ecophysiology of canopy
trees in lowland Thailand and related data analysis
are released in “Scientific Data” on September 8 in
2023. “Scientific Data” is a peer-reviewed, openaccess journal of Springer Nature Group for
descriptions of scientifically valuable datasets andresearch, and is a new type of publication that
focuses on helping others reuse data crediting those
who share. The title of the published paper is”Comparative physiology of canopy tree leaves inevergreen and deciduous forests in lowland
Thailand” (Ishida et al. 2023), and the raw dataset isdeposited in “Dryad Digital Repository” (Ishida etal. 2022), which is available for own analysis, suchas Meta-analysis.

in Kanchanaburi Province and 2) dry evergreen
forest (DEF) and dry dipterocarp forest (or dry
deciduous forest) (DDF) in the Sakaerat
Environmental Research Station (14°29′ N, 101°55′
E, 1610 m above sea level) in Nakhon Ratchasima
Province, Thailand (Fig. 1). The Mae-Klong
Watershed Research Station is located at
approximately 250 km northwest of Bangkok, andthe Sakaerat Environmental Research Station is
located at approximately 180 km northeast of
Bangkok (Fig. 2). The number of sampled trees is107, 65 and 51 tree species in MDF, DEF and DDF,
respectively. Approximately 70%, 95% and 95% of
canopy tree species which consist of MDF, DEF and
DDF are sampled, respectively. The dataset wascollected by the members of my laboratory and
DIWPA members from research institutes anduniversities in Thailand.

In the depository data, any persons canobtain 21 ecophysiological traits of the top/sunlit
leaves of trees in three forest types: 1) mixed
deciduous forest (MDF) in the Mae-Klong
Watershed the Mae-Klong Watershed Research
Station (14°34′ N, 98°50′ E, 400 m above sea level)(A)

In Thailand, the Chao Phraya River flows
from north to south, and on either side of the river
there are different topography and geologies (Fig.

(B)

(C)

Fig. 1. Photos of (A) Mixed deciduous forest (MDF; July 2007) at the Mae-Klong Watershed Research Station, and (B) Dry evergreen forest (DEF; July 2007) and (C) Dry
deciduous forest or Dry dipterocarp forest (DDF; September 2010) at the Sakaerat Environmental Research Station. The top-canopy heights of MDF, SEF and DDF areapproximately 30m, 35m and 15m high above the ground, respectively.

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DIWPA News Letter No.49

3). In climate, there is a distinct dry season lasting
several months from December to February inoverall Thailand and adjacent areas of Southeast
Asia. The mechanisms for overcoming the severe
dry season are evolutionally resultant for trees inthis area. The analyzed results (Ishida et al. 2023)
show a high biodiversity of leaf traits among theforest types, and the specific leaf traits related tosoil properties in each forest type. This factindicates that there is the mechanism of niche

segregation in forest trees (forest types) based on
edaphic factors, such as soil thickness and available
nutrients. The mountain range in north-western
Thailand along the border with Burma is steep andrugged and cuts into narrow valleys. Few peaks
exceed an elevation of 1800 m. The Himalayan
orogenic movement formed these steep mountains,
and the resulting soil in this area originated from thelimestone of the Mesozoic Era. Tsutsumi et al.
(1996) and Rundel and Boonpragob (1995) showedthat the soils of limestone areas have highphosphate (P) concentrations. In this area, DDFs arescattered on mountain ridges where the soil isextremely shallow. The Himalayan orogenic
movement caused a north-south division throughthe Chao Phraya River, promoting speciation oftrees between the eastern and western parts ofThailand. The north-eastern Thailand consists of the
Khorat Plateau (located on the eastern side of the
Chao Phraya River), which covers nearly one-thirdof the country’s area. This area is drained by atributary of the Mekong River, and the soil
originated from sandstone created in the Cenozoic
Era. Several hills with gentle slopes from elevationsof 650 to 250 m are scattered on this plateau. The
tops of hills generally have deep sandy soil
extending from the ground surface to the bedrock,while the foots of hills have shallow sandy soil

(A)

(B)

Sakaerate

Bangkok

300 km
Mae-Klong
Fig. 2. The limestone area (orange color) in
Thailand and the positions of Bangkok and two
study sites, the Mae-Klong Watershed Research
Station (Mae-Klong) and the Sakaerat
Environmental Research Station (Sakaerat).

Fig. 3. The landscape of (A) the east side and (B) the west side of the Chao Phraya River in Thailand. (A) A limestone mountain and Mixed deciduous forest (MDF)
including bamboo forests. In the north-eastern Thailand, Myanmar and India on the east side of the Chao Phraya River, the Himalayan orogenic movement formed
these steep mountains, and the resulting soils originated from the limestone of the Mesozoic Era. (B) The Khorat Plateau and Dry deciduous forest or Dry dipterocarp
forest (DDF). In the eastern Thailand and Laos on the east side of the river, it is less affected by this movement and there is a widespread Khorat Plateau with sandstone
bedrock created in the Cenozoic Era. This Plateau is drained by a tributary of the Mekong River.

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DIWPA News Letter No.49

High →

DEF
Sandy soiltype MDF (?)← Low

Soil thickness(Water availability)

because of soil erosion. These sandy soils have poor
nutrient concentrations. In the Khorat Plateau, DEFs
usually develop on hill tops with deep sandy soil,
whereas DDFs usually develop on foothills withshallow sandy soil. Therefore, the evergreen forests(DEFs) and deciduous forests (DDFs) haveseparately established within the same hills along
the soil thickness gradient in the topography.

DDF
← Low

In Thailand, drought-deciduous trees are
predominant in MDF and DDF, whereas evergreen
trees are predominant in DEF. The canopy leaves of
MDF (at the Mae-Klong) are significantly thinnerand have significantly higher P concentrations andlower photosynthetic water use efficiency (netphotosynthetic rates/stomatal conductance ratio)
than those of DDF and DEF (at the Sakaerat). Theseleaf traits and deciduous phenology indicates lessconservative resource use strategy (especially in P
and water) adapting to the eutrophic, liming soils of
MDF, because of contributing to a high carbon gain
during a short growing period (Ishida et al. 2006,
2010, 2014). It has also been reported that on theisland of Borneo, P concentrations within leaves
increases and leaf thickness decreases withincreasing P availability in soils (Hidata andKitayama 2011, Bartholomew et al. 2022). BothDDF and DEF develop in sandy soil sites with poor
nutrients at the Sakaerat; DDF establishes at thinsoil sites, whereas DEF establishes at thick soil sites(Murata et al. 2009). Thus, the differences of soil
thickness are dependent on deciduous phenology(DDF) and evergreen phenology (DEF) of canopy
trees, adapting to soil water availability to overcome
the dry season. If the canopy leaves use water evenin the dry season due to thick soil, evergreen
phenology are more adaptive to deciduous
phenology, because approximately 50% nutrients
within leaves are lost when leaf falling (Vergutz etal. 2012). Our data provide evidence supporting thepivotal role of topography and edaphic factors (soilnutrients and water) in determining the habitat
associations of diverse forest types andcorresponding leaf functional traits within theseasonally dry tropical forests. This fact indicatethat there is the mechanism of niche segregation

Liming soiltype MDF

High →

Soil nutrient availability

Fig.4. Schematic diagram of the distribution of three different forest types, DDF(Dry dipterocarp forest or Dry deciduous forest), MDF (Mixed deciduous forest)
and DEF (Dry evergreen forest), along the axes of soil thickness (soil water
availability) and soil nutrients availability as the forest establishment factors.
More research is needed to recognize sandy soil-type MDFs.

along the axes of soil thickness (water availability)
and soil nutrient availability (Fig. 3). Nevertheless,at the Sakaerat with sandy soil, the top-canopy
heights of tree gradually increase with soil thickness
from DDF to DEF sites, forming ecotone forests.
Leaf and forest function of MDF in sandy soil sites
could be different from the MDF examined in thecurrent study (limestone site), suggesting that
MDFs include two forest types of sandy soil-type
MDF (or ecotone-type MDF) and liming soil-type
MDF (Fig. 4). More research is needed to compare
the tree physiology and forest function of MDFs inSoutheast Asia.
In Thailand and adjacent areas in Southeast
Asia, forest trees and types are separated by niche
segregation due to the difference of soil properties
and topology, such as soil thickness and bed rocktypes, resulting from the ancient history of plate
tectonics and river drain. Similar to Thailand
forests, such edaphic niche segregation among tree
species has been reported in Bornean rainforests(e.g., Jucker et al. 2018, Bartholomew et al. 2022)
and Neotropical dry forests in South America (e.g.,Powers and Tiffin 2010, DryFlor 2016). Recently,
anthropogenic impacts have been increasing
globally in tropical dry forests, requiring a highpriority for conservation. The accelerated
development of agricultural land progresses forest
fragmentation, resulting in vegetation changes
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DIWPA News Letter No.49

Ishida, A. et al. 2023. Comparative physiology of canopy tree leaves inevergreen and deciduous forests in lowland Thailand. Sci. Data 10:601. https://doi.org/10.1038/s41597-023-02468-6
Jucker, T. et al. 2018. Topography shapes the structure, composition andfunction of tropical forest landscapes. Ecol. Lett. 21, 989–1000.
Murata, N., Ohta, S., Kanzaki, M., Wachirinrat, C., Artchawakom, T. andSase, H. 2009. Comparison of soil depths between evergreen anddeciduous forests as a determinant of their distribution, Northeast
Thailand. J. Forest Res. 14, 212–220.
Popradit, A. et al. 2015. Anthropogenic effects on a tropical forest
according to the distance from human settlements. Sci. Rep. 5,14689.
Rundel, P. W. and Boonpragob, K. 1995. Dry forest ecosystems ofThailand. In Seasonally Dry Tropical Forests, pp. 93–123, Cambridge,
UK. Cambridge University Press.
Sase, H. et al. 2016. Alkalinization and acidi cation of stream water withchange in atmospheric deposition in a tropical dry evergreen forestof northeastern Thailand. Hydrol. Process. 31, 836-846.
Tsutsumi, T., Suga, M. and Khemanark, C. 1996. The amount of plant
nutrients and their circulation in the forest soils in Thailand. Carbon and nitrogen contents and some physical properties of theforest soils. Jpn. J. Southeast Asian Stud. 4, 327-366 (in Japanese).
Vergutz, L., Manzoni, S., Porporato A., Vovais, R. F. and Jackson, R. B.
Global resorption ef ciencies and concentrations of carbon andnutrients in leaves of terrestrial plants. Ecol. Monogr. 82, 205-220.

particularly in the peripheral areas of the forest in
Thailand (Popradit et al. 2015). The amounts ofsulfur oxides deposited from the atmosphere toplants and soil has been increasing in Thailand,
resulting in changes in the chemical properties offorests (Sase et. al. 2016). Such enhanced
anthropogenic influences and climate change may
significantly impact the forest function and theirhabitat associations in future. The current dataset
will not only be relevant to the response of forests
to environmental changes but also provide insights
into the restoration of degraded forests.
References
Bartholomew, D. C. et al. 2022. Differential nutrient limitation and treeheight control leaf physiology, supporting niche partitioning in
tropical dipterocarp forests. Funct. Ecol. 36, 2084– 2103.
Hidaka, A. and Kitayama, K. 2011. Allocation of foliar phosphorus
fractions and leaf traits of tropical tree species in response to
decreased soil phosphorus availability on Mount Kinabalu, Borneo.
J. Ecol. 99, 849-857.
Ishida, A. et al. 2006. Contrasting seasonal leaf habits of canopy trees
between tropical dry-deciduous and evergreen forests in Thailand.
Tree Physiol. 26, 643-656.
Ishida, A. et al. 2010. Seasonal variations of gas exchange and water
relations in deciduous and evergreen trees in monsoonal dry
forests of Thailand. Tree Physiol. 30, 935-945.
Ishida, A. et al. 2014. Photoprotection of evergreen and droughtdeciduous tree leaves to overcome the dry season in monsoonal
tropical in deciduous and evergreen trees in monsoonal dry forestsof Thailand. Tree Physiol. 34, 15-28.
Ishida, A. et al. 2022. Data from: Comparative physiology of canopy tree
leaves in evergreen and deciduous forests in lowland Thailand.
Dryad Digital Repository. https://doi.org/10.5061/dryad.12jm63z10

Mail Us!
We welcome your articles,
news or any information related tobiodiversity.
Please send them todiwpa@ecology.kyoto-u.ac.jp

DIWPA OFFICE
Chairperson

Shin-ichi Nakano

Secretary General

Atsushi Ishida

Secretary

Keisuke Koba Hiroshi Kudo
Shigeo Yachi

Center for Ecological Research
Kyoto University509-3, 2-chome, Hirano, Otsu, Shiga 520-2113, JAPANTel : +81-77-549-8238
E-mail : diwpa@ecology.kyoto-u.ac.jp

Hiroyuki Tanaka

http://diwpa.ecology.kyoto-u.ac.jp/

Assistant Secretary Akiko Seki

fi

fi

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DIWPA News Letter No.49