10th International Conference on Development of Drylands
Meeting the Challenge of Sustainable Development in Drylands under Changing Climate – Moving from Global to Local
Cairo, Egypt 12-15 Dec 2010.
SUSTAINABLE DEVELOPMENT IN DRYLANDS
Theme 1: Assessment of climaticchange in arid lands
1. Rapid measurement of dust emission from semi-arid to hyperarid
landforms across the Southwest U.S.
and Israel: Implications for the assessing impacts of global climate change
on wind erosion and dust emission
Eric V. McDonald* and S.N. Bacon
Division of Earth and Ecosystem Sciences, Desert Research
Institute, Reno, NV 89512, USA. *E-mail: [email protected]
Forecasted changes in global climatic patterns
will impact the formation and sustainability of soil
crust (physical, chemical, and biologic) resulting in
possible profound changes in dust emission from
dryland soils. Assessment of potential changes
in dust emission potential at the local level is
difficult because traditional in situ measurements
involve large (~5-10 m in length) and expensive
wind tunnels that have limited application to the
extensive areas of dryland soils common to nonagricultural settings. We began a campaign to
directly measure dust emissions under disturbed
and undisturbed surface conditions within the
Mojave and Sonoran Deserts of southwest U.S. and
within Negev Desert of Israel using the Portable
in situ Wind Erosion Lab (PI-SWERL). The PISWERL is a novel device for measuring dust
emissions from soil surfaces that requires limited
setup time and allows for rapid measurements.
Originally PI-SWERL was limited to measuring
particles with diameters of 10 microns (PM10) or
less; however, we recently modified PI-SWERL so
that it is now capable of measuring total suspended
particle (TSP) emission flux from extremely
dust-rich and highly erodible surfaces under high
friction velocities. Results indicate that the PISWERL provides a reasonable measure of dust
emission over a range of soil types having a variety
of textures, crust characteristics, and roughness
elements. The magnitude of TSP emission flux
from arid landforms is largely controlled by
geomorphic setting, soil properties, and type of
23
surface conditions. The types of geomorphicbased emissions data measured from landforms
in semi-arid to hyperarid environments will help
to quantify variables used to make dust-emission
terrain-based hazard maps, provide information to
refine dust emission models related to global-scale
atmospheric dust loading, as well as help to provide
information for the mitigation of wind erosion by
incorporating potential emissions larger than the
PM10 particle size.
2. Rangeland vegetation assessment
in the Eastern and Western regions of
Libya
Fahim Ghassali1, Hassan Steita2, Souleiman Bel
Kheir2, Khalfallah Mustafa ben Hcine2 and Mounir
Louhaichi1
1
International Center for Agricultural Research in the Dry
Areas (ICARDA), Aleppo, Syria; e-mail: [email protected];
[email protected]; 2Agricultural Research Center (ARC),
Libya
Rangelands in the dry areas of the Southern
Mediterranean basin extend over large areas,
constituting one of the dominant forms of land use
in the area. These are often hot spots of biodiversity
and are threatened by encroachment of farming
practices, overgrazing and climate change. Thus,
there is an urgent need to rehabilitate and better
manage these degraded lands. However, the first
step before engaging in any rangeland rehabilitation
and management project should be centered toward
mapping and assessing rangeland condition. The
purpose of this study is to investigate the current
status of rangeland vegetation in Libya. To meet
this objective during the spring of 2010, a team
from ICARDA and ARC-Libya conducted a
vegetation assessment across several sites in the
eastern and western parts of Libya. Conventional
sampling techniques for rangeland monitoring and
assessment including quadrates and line intercept
as well as near-earth remote sensing technology
were adopted. Vegetation parameters recorded were
standing biomass, cover, frequency and density.
Preliminary results indicated that total biomass
and plant density were significantly different by
10th International Conference on Development of Drylands
Meeting the Challenge of Sustainable Development in Drylands under Changing Climate – Moving from Global to Local
Cairo, Egypt 12-15 Dec 2010.
24
SUSTAINABLE DEVELOPMENT IN DRYLANDS
region: 172 kgDM/ha and 42 plant/m2 for the
east compared to 673 kgDM/ha and 100 plant/m2
for the west. Percent green cover as estimated by
the digital charting technique showed differences
between and within the two regions. Sixty-one
species from 22 families were observed in the
eastern region compared to 92 species from 29
families in the western region. The differences
were not reflected in the plant diversity and
richness as the two regions showed similar results
in vegetation cover (25%), species richness (9
species) and Shannon diversity index (1.8). Annual
species were dominant in the east and had low
biomass while perennial shrubs species dominated
the west. Human induced activities, in particular
cultivation and overgrazing, could have contributed
to the existing spatial variability. The information
gathered in this study can provide baseline data
needed for a proper future monitoring of these
natural resources.
3. Relationship between AVHRR
NDVI and precipitation in northern
China
increased linearly (P<0.001) through both AP and
AEP gradient, but increased nonlinearly through
APU gradient. There are 82, 78 and 33 stations
of 297 with positive linear relationship (P<0.05)
between NDVI and AEP, AP and GSP respectively
and 50 stations with negative linear relationship
(P<0.05) between NDVI and APU. Moreover, most
stations with NDVI significantly linearly related
to precipitation parameters are distributed within
the 200-400mm annual precipitation isoline. Our
results confirm the lag effect of precipitation on
vegetation and also help understand the tendency
and spatial pattern of vegetation response to climate
change.
4. Long-term trend analysis in heavy
and extreme events in semi-arid
rainfall station, as an indicator of
climate change
Khaldoon A. Al-Qudah1 and Abdullah A. Smadi2
1
UNESCO Chair for Desert Studies; e-mail: [email protected].
jo; [email protected]; 2 Statistics Department; Faculty of
Science, Yarmouk University, Irbid 21163, Jordan
Guo Jian* , Wang Tao and Xue Xian
Key Laboratory of Desert and Desertification, Institute of Cold
and Arid Regions Environmental and Engineering Research,
Chinese Academy of Sciences, No. 320 Donggang West Road,
Lanzhou 730000, Gansu Province, China; *e-mail: keen@lzb.
ac.cn
Water is a primary resource limiting terrestrial
biological activity, particularly in arid and semiarid regions. This study focuses on the temporal
and spatial variation between vegetation green
biomass and precipitation parameters (annual
precipitation AP, annual efficient precipitation AE),
annual precipitation uniformity APU and growing
season precipitation GSP) in northern China. The
relationship between vegetation and precipitation
was investigated with Normalized Difference
Vegetation Index (NDVI) images (1982–2006)
derived from the Advanced Very High Resolution
Radiometer (AVHRR), and precipitation data
from 297 weather stations throughout northern
China. Results indicate vegetation green biomass
Trends in extreme events have been worldwide
analyzed as an indicator of change in climate driven
by increase in atmospheric greenhouse gases.
Statistical analysis of heavy (i.e. maximum, 75th
and 90th percentiles ) daily rainfall for 86 years
for a semi arid rainfall station in Jordan has been
presented. The regression approach as well as
the Mann-Kendall test were used to investigate
significant trends in those data. Both methods
assure a significant downward trend. It is however
observed that other related variables including
yearly total rainfalls and the number of rainy days
per year do not show any significant trend. It is
also observed that the fitted linear trend model
of maximum daily rainfall shows an estimated
rate of decrease of nearly 2mm per decade. A
plausible change in the trend is detected in the year
1982/1983. The fitted trend models for both periods
show that the rate of decrease after the change point
is doubled. Finally, “extreme events” of maximum
daily rainfalls are investigated through the readings