Tugai forests at the Tarim middle reaches, Xinjiang, China ecology, conservation, and restoration Niels Thevs Institute of Botany and Landscape Ecology Greifswald University

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Tugai forests at the Tarim middle reaches,
Xinjiang, Chinaecology, conservation, and
restoration Niels ThevsInstitute of Botany
and Landscape EcologyGreifswald University
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Contents ??
Introduction into the term Tugai
?????????? Introduction of the study area, the
Tarim Huyanglin Nature Reserve (geomorphology,
hydrology, people and land use)
?????????????,?????????????? Introduction of the
two research items spatial distribution of Tugai
vegetation and recruitment of Tugai forests with
methods and results ??Tugai??????????????? Conclu
sions regarding conservation of the Tugai
vegetation ??????????
Cooperation of the Institute of Resource and
Environmental Sciences of Xinjiang University and
the Institute of Landscape Ecology and Botany of
Greifswald University
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Definition of the term Tugai forest??????????
Riparian forests of the deserts and semi-deserts
of Central Asia. ????????? Tugai forests are
mainly built by Populus euphratica, Populus
pruinosa, Elaeagnus oxycarpa, and Salix species.
Populus euphratica? Populus pruinosa? Elaeagnus
oxycarpa?Salix????????????????
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Ecological functions of Tugai forest??????????
Tugai forests are the hotspot of biodiversity in
the deserts of Central Asia. ?????????????????? T
hey serve as windbreak, serve for sand fixation
and provide fodder and shelter for wild and
domestic animals. ??????????????????????????????
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Destruction of Tugai forests ???????? Xinjiang,
China 1958 500,000 ha Tugai forest 1978
150,000 350,000 ha Aral Sea Basin / Amu
Darya 1950 500,000 ha Tugai forest 1998 70,000
ha
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Strategy to survive in the desert
environment??????????
P. euphratica, as well as the other species of
the Tugai forests, is a phreatophyte. ??????? Phre
atophytes continuously contact the groundwater
and thus ensure their water supply. ??????????,???
?????? P. euphratica can live on groundwater as
deep as 12 m below surface. It forms the Tugai
forests along the Tarim River. ???????12???????? T
he groundwater mostly is replenished by river
courses. ???????????
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Recruitment of Populus euphratica?????
Seeds germinate after floods on moist,
non-saline, freshly deposited river banks free of
other vegetation. Seeds germinate in belts
according to flood lines. ??????????????????????,
???????????????????????????
On non-flooded sites P. euphratica trees
reproduce vegetatively. Older stands are composed
from clones. ???????????????????????????????????
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Research objectives????
Investigate the current distribution of Tugai
forests and other Tugai vegetation. ??????????????
????? Investigate the conditions needed for the
recruitment Populus euphratica as key-stone
species of the Tugai forests along the Tarim
River. ???????????????
Conclusions for conservation of the Tugai forests
and Tugai vegetation. ?????????????????
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The study area (Tarim Huyanglin Nature
Reserve)????(???????????)
930 m
920 m
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Monthly discharge of the Tarim at
Yingbaza??????????
The Tarim River is fed by precipitation (summer
maximum) in the mountains (mainly Tianshan) and
melting water. ???????????????? Each flood can
alter the river course, as the Tarim River flows
in a level flood plain. ????????
Data provided from Tarim Watershed authority and
Prof. Nurbay Abdusalih
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River course changes of the Tarim
Tarim 1903 Source Hedin (1905)
1949 (light grey Tarim 1903) Source China
Geodesy Bureau (1959)
1973 (light grey Tarim 1949) Source Landsat MSS
1973/10/20
2000 (light grey Tarim 1973) Source Landsat ETM
2000/07/06
Boundary of the Tarim Huyanglin Nature Reserve
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Tamarix dunes, P. euphratica stands on fluvial
sediments
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P. euphratica stand at the desert margin
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Tugai forest, periodical river branch of the
Tarim River
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Flood marks from 2006-summer-flood
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Tarim River at Iminqäk
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Regulation of the Tarim River ???????
Objective Ensure water supply for the lower
reaches of the Tarim after 30 years of
drought. ?? ??????30????????????
Tarim Watershed Administration, 2003
Measures ?? Divert water from the neighboring
Kaidu-Kenqi watershed into the Tarim lower
reaches. ???-?????????????? Construct dykes
along the main river course of the Tarim to
channel water through the inland delta down to
the lower reaches. River branches are cut
off. ???????????,?????????????????????????????????
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Poeple and land use?????????
Traditionally Uyghur people herd sheep and goats
and have small fields and gardens around
villages. ???????????,???????
After 1995 large scale cotton fields were opened,
mostly by Han-Chinese from outside the area.
1995????????,???,??????????????
After 2003 ecological resettlements were
conducted (e.g. Caohu). After local people had
been settled away, the land was given to new
immigrants and the area under cotton was
enlarged. 2003??????????????,????????,?????????
???,????????
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Investigation of the current distribution of
Tugai forests and other Tugai vegetationmethods?
????????????????? ??
Classification of two Landsat ETM images to
derive a land cover map. ????Landsat???,??????? Im
ages path 144, row 31, 2000/07/06 (representing
base flow), 2001/08/10 (representing flood). ???
path 144, row 31, 2000/07/06 (???), 2001/08/10
(????). Ground truth data 286 vegetation
samples, 145 training sites, 141 validation
sites. ????286?????
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Recruiment conditionsmethods?????????????? ??
Investigation of Tugai forests formation
(vegetation map, tree ages, soil sampling) at a
still natural site with river relocation (site in
Iminqäk). ?????????????,???????(????)????????????
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Transect Ia Iminqäk river course changes??????
????
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River bank changes at transect Iminqäk??????????
Background Quickbird image, 2005/06/15
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Transect Iminqäk - elevation, soils,
vegetation?????? ??????????
Tarim river bank between 1973 and
1992 1973??1992??????
P. euphratica row from germination before
1992. ???,1992??????
P. euphratica shrubs in between root suckers.
??????????????
Germination belt from 2002 2002?????????
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Discussion I?? I
Dense Tugai forests are restricted to belts of 1
km width along river courses. Tugai shrubs occur
still further away from river courses.
???????(?????)????????1???????????(??)
1?????????? The large contiguous area of Tugai
forests in Iminqäk is a result of a dense web of
river branches, which are still
flooded. ?????????????????????????????
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Discussion II ?? II
Germination frequently takes places, but
establishment is the bottleneck. ????????,???????
Seeds germinate in autumn and seedlings have to
survive the spring and summer of the following
year. During spring and summer the groundwater
level drops 2,5 3 m below surface at the
germination site. ??????,????????????????????????
????2.5-3??
Seedlings may survive either through an early
onset of the flood in the year after germination,
or seedlings may survive through silty and clayey
soil layers, which store water better than
sand. ?????????????????????,????????,?????
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Conclusions regarding conservation and
restoration of Tugai forests?????????????
River courses without dynamics replenish the
groundwater and thus sustain existing Tugai
vegetation. ???????????????????,????????????
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River courses with dynamics and flood events
foster the generative reproduction and
establishment of P. euphratica as key-stone
speices of the Tugai forests along the Tarim
River and maintain the genetic diversity of this
species. ??????????????????????,???????????
River dynamics and flood events are the
key-factors for the conservation and restoration
of Tugai forests. ????????????????????
River course stretches with still prevailing
river dynamics, i.e. Iminqäk, should become core
zones for the conservation of Tugai forests.
?????????(?????)??????????????
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Conservation and land use???????
Animal herds must be kept away from P. euphratica
seedlings. Herd sizes must be limited within the
Chengbao-Contracts on land tenure. Herding with
limited herd sizes can leave space for nature, as
we found in Iminqäk. ????????????????????????
Irrigation agriculture (i.e. cotton) must be
taken out of the Tarim Huyanglin Nature Reserve.
Growing reed might be an alternative. ????????????
???????????????
Ecological resettlement must be stopped, because
the local people know better to deal with the
Tugai vegetation than the immigrating
people. ????????,?????????????????
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Abandaned cotton field, Iminqäk
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Thanks to the colleagues and funding
organisations The colleagues from Xinjiang
University and Bügür Prof. Nurbay Abdusalih,
Muzappar Mijit, Dr. Ümüt Halik, Prof. Mijit
Hudaberdi, Prof. Huang Peiyou, Li Daping, Ghalip
Jan The supervisors and colleagues from
Greifswald University Prof. Succow, Prof. Zerbe,
Prof. Schnittler Jan Peper, Philipp Pratap Thapa,
Franziska Gahlert, Susanne Abel, Nadine Jeschke,
Martin Wiehle Funding organisations Volkswagen
Foundation, Heinrich-Böll-Foundation, DAAD