Land use/land cover changes and regional climate over the Loess Plateau during 2001–2009. Part I: observational evidence
Xingang Fan
0
1
Zhuguo Ma
0
1
Qing Yang
0
1
Yunhuan Han
0
1
0
R. Mahmood Kentucky Climate Center, Western Kentucky University
, Bowling Green,
KY 42101, USA
1
Y. Han University of Chinese Academy of Sciences
,
Beijing 100049, China
Adverse environmental impacts from deforestation are a growing area of concern in climate change discussions. The Chinese government has implemented a series of policies, such as the Grain for Green Project, in an attempt to mitigate the impacts. This study takes a regional perspective to report land use/land cover changes over the Loess Plateau region from 2001 to 2009. MODIS data were used in analyzing both the conversions among and the resulting changes in different land types. Government statistical census data and observed climate data were also incorporated in the analysis. A general consistency is shown in both remotely sensed and census data. With the implementation of various projects, including the Grain for Green Project, the total
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areas covered by grassland, cropland, and forests have increased by 19.2 % (6.05104 km2),
33.7 % (5.80104 km2), and 19.6 % (3.08104 km2), respectively, during the 9-year period.
While climatic conditions, particularly annual precipitation totals, usually dominate the
distribution of vegetation, it is found that socioeconomic polices and human activities contribute to the
increase in overall greenness and to vegetation growth (e.g., LAI increased by 16.8 % (0.10)
overall). However, the feedback of land use/land cover to regional climate is complicated and
cannot be easily distinguished from natural climate variations based on short-term observational
data alone. To better isolate the effects, further analysis and modeling studies are suggested.
1 Introduction
To address various types of natural disasters and environmental crises, China has implemented
largescale reforestation/afforestation policies to contribute to a sustainable environment (e.g., Liu et al.
2008). The most well known government-funded program is the Grain for Green Project (GFGP),
which focuses on the return of terrace-farming croplands to forests/grasslands with compensation
from the state (e.g., Tao et al. 2004). This policy has resulted in large-scale redistribution of land-use
rights and has been ongoing for more than a decade throughout China (Hvistendahl 2012). Some of
the immediate benefits include increased vegetation coverage, soil erosion control, and reduced
spread of wind-blown dust. However, additional longer-term and larger-scale ecological,
environmental, and climatic impacts may also be occurring (Pielke 2005; Bonan 2008; Liu et al. 2008).
The Loess Plateau, located northeast of the Tibetan Plateau in northern China (Fig. 1), has garnered
much attention due to its climate and land use/land cover (LULC) characteristics, and was chosen for a
pilot GFGP in 1999 (Editorial Board of the China Yearbook 2002). It comprises a mix of arid,
semiarid, and semi-humid areas, with an ecosystem that is sensitive and susceptible to climate transition
due to global climate change (Liang et al. 2008). Drought, soil erosion, and desertification are ongoing
concerns to local inhabitants whose agricultural activities and productivity rely largely on the
availability of precipitation. The GFGP resulted in relatively rapid increase of overall greenness in
early 2000s (e.g., Xin et al. 2008) and LULC changes are reported for many local counties (e.g., Cao
et al. 2007; Wang et al. 2010; Zhou et al. 2012). This unique mixture of natural and artificially
modified environments on the Loess Plateau serves as an ideal platform for the investigation of
interactions between changes in ecosystem and climate (e.g., Cao et al. 2007; Liang et al. 2008).
Fig. 1 Loess Plateau study area: a Topography and location of the study area, with the black box marking the 112.2
104 km2 area over 102114E and 3241N; b Satellite view of the area (extracted from http://mapsof.net/uploads/
static-maps/china_satellite_photo.jpg); the small box marks the location where LandSat images are shown in Fig. 2
The Chinese government has promoted a policy encouraging afforestation since the 1980s. This
developed into the adoption of a more proactive step through the enforcement of a pilot GFGP on
the Loess Plateau in 1999, including the provinces of Sichuan, Shaanxi, and Gansu; a nationwide
GFGP was enacted in 2003. China invested about Chinese currency RMB 190 billion (equivalent of
USD 23.2 billion) over a 10-year period (19992008) to subsidize farmers in regions with poor
agricultural production or severe land erosion problems to enforce implementation of the GFGP,
with an additional RMB 10 billion (USD 1.4 billion) pledged through 2015 (National Bureau of
Statistics of China 2009b). Since the initial implementation of the GFGP in 1999, many studies have
focused on its impacts at scattered local and small-regional scales. For example, Cao et al. (2007)
reported that, in northern Shaanxi province, afforesta (...truncated)