National Ecological Barrier Zone 1 km Resolution
Net Primary Productivity Dataset (2000–2015)
Wang, X. F.1,2* Wang, Y.1 Yin, L.C.3,4
1. The College of Land Engineering, Chang’an
University, Xi’an 710054, China;
2. The Key Laboratory of Shaanxi Land Consolidation
Project, Chang’an University, Xi’an 710054, China;
3. Key Laboratory of Land Surface Pattern and
Simulation, Institute of Geographic Sciences and Natural Resources Research,
Chinese Academy of Sciences, Beijing 100101, China
4. University of Chinese Academy of Sciences, Beijing 100101, China
Abstract: As the basis
of ecosystem material and energy cycle, net primary productivity (NPP) can
reflect the carbon sequestration capacity of vegetation at regional and global
scales, which is an important indicator to evaluate the quality of terrestrial
ecosystem. Aiming at the production of NPP, based on the principle of light
energy utilization rate model and coupled with remote sensing, meteorology, vegetation
and soil type data, we conducted a modeling study on the ecosystem productivity
of the national barrier zone. In the calculation of parameters, the
photosyntheticallyactive radiation (APAR) was calculated from the data of
MOD13A2 NDVI, vegetation map of China, total solar radiation, temperature and precipitation.
Compared with other studies and models, the regional evapotranspiration model
was used to simulate water stress, in which complex soil parameters
are avoided and the operability of the model is enhanced. Taking APAR and
actual light energy utilization rate (ε) as input variables of parameterized
model-CASA model, the estimation of the national ecological barrier zone 1 km
resolution net primary productivity dataset from 2000 to 2015 was realized. Compared
with MOD17A3 NPP data of 2000, 2005, 2010 and 2015, the two data have good
consistency. The data format is ArcGIS TIFF and ZIP, the unit is gc/m2,
and the projection coordinate system is WGS_1984_Albers. The spatial resolution
is 1 km, and the total size of compressed dataset is 53.8 MB.
Keywords: national
ecological barrier zone; net primary productivity; light energy utilization
rate; CASA model; geographical research
1 Introduction
Net primary productivity (NPP) refers to the total
amount of organic matter produced by green plants in unit time and area in terrestrial
ecosystem[1], that is, the
difference between carbon absorbed by photosynthesis and carbon released by
respiration[2]. It is the result of mutual adaptation of plant
biological characteristics and external environment, and is the material and
energy basis for the survival of heterotrophic organisms. As the core parameter
of terrestrial ecosystem carbon cycle[3],
it can not only represent the assimilation effect of the ecosystem on carbon[4],
but also is an important index to evaluate the stability of ecological
structure and function[5]. It is also the main factor to determine
the carbon source/sink and regulate the ecological process[6].
Therefore, in the context of global climate change, scholars attach great
importance to the study of NPP, and global change and terrestrial ecosystem
(GCTE) has identified it as one of the core contents of the research[7].
“Two barriers and three belts” ecological barrier zone is an important part of
the national ecological security strategic pattern. In response to the
"two barriers and three belts" national ecological security barrier
framework proposed by the government in the national major function oriented
zoning, Bojie
Fu et al.[8]described the scope
of the national barrier zone on the basis of ensuring the integrity of the
county and carried out a comprehensive assessment of ecosystem services from
2000 to 2010. The main purpose of this dataset is to construct NPP time series
products of national barrier zone, to carry out research on trade-offs and
synergies of ecosystem services, and to ensure human rights and well-being. The
national ecological barrier zone 1 km resolution net primary productivity
dataset (2000–2015) is an important output of ecosystem service science. It is
also a vital digital resource for monitoring and evaluating NPP evolution of
ecological environment and sustainable development of ecosystem. In this study,
we introduced the detailed information of the data, the basic principles of the
algorithm, and verified the accuracy of the data.
2 Metadata of the Dataset
The name, short name,
authors, geographical region, data age, data resolution, data format, publisher
and sharing policy and other information of the dataset are listed in Table 1.
3 Methods
The production of national ecological barrier zone 1 km resolution net
primary productivity dataset (2000–2015) is based on a 16 day composite product
of MOD13A2 1 km vegetation index
(https://ladsweb.modaps.eosdis.nasa.gov/search/order/), China surface climate
data daily data set (V3.0) (http://www.cma.gov.cn/), etc. Based on the CASA model, the quantitative output of NPP was obtained.
3.1 Overview of the Study Area
The national barrier zone
(22°45¢N-53°34¢N, 82°50¢E-134°22¢E) is vast, including the ecological barrier of the Qinghai Tibet Plateau,
the northeastern forest zone, the northern sand belt, Sichuan Yunnan-loess
plateau ecological barrier and the southern hill and mountain belt. The total
area of the barrier zone is 3,114,874.36 km2, accounting for about
1/3 of the total land area of China. It includes 18 provinces and 482 counties.
The precipitation decreases from southeast to northwest, and the annual average
temperature is-6-23 ℃. The ecosystem types of the study area are
diverse and the natural environment is complex[10-12].
3.2 CASA Model
The Carnegie Ames-Stanford Approach (CASA)[13] model based on the principle of
light energy utilization was used to quantify the annual NPP in the national
ecological barrier zone. This method can make use of remote sensing data and
methods conveniently, and has less input parameters, so it has become one of
the most popular NPP estimation models in the world. The calculation equation is as follows:
(1)
Table 1 Metadata summary of national ecological barrier zone 1 km
resolution net primary productivity dataset (2000–2015)
Items
|
Description
|
Dataset full name
|
National
ecological barrier zone 1 km resolution net primary productivity dataset
(2000–2015)
|
Dataset short
name
|
NBZ_NPP_1
km_2000-2015
|
Authors
|
Wang, X. F.
AAS-5271-2020, The College of Land Engineering; the Key Laboratory of Shaanxi
Land Consolidation Project, Chang’an University, wangxf@chd.edu.cn
Wang, Y.
AAS-5036-2020, The College of Land Engineering, Chang’an University, wangyichangan134@163.com
Yin, L. C.
AAS-4914-2020, Key Laboratory of Land Surface Pattern and Simulation, Institute
of Geographic Sciences and Natural Resources Research, Chinese Academy of
Sciences; University of Chinese Academy of Sciences,yinlichang3064@163.com
|
Geographical
region
|
The provinces
involved in the study area include Heilongjiang, Jilin, Qinghai, Gansu, Sichuan,
Xinjiang, Inner Mongolia, Hebei, Liaoning, Tibet, Ningxia, Yunnan, Guangxi,
Guangdong, Guizhou, Hunan, Jiangxi and Shanxi
The northern sand
belt(75°50¢E - 124°18¢E, 36°45¢N - 45°06¢N)
The ecological
barrier of the Qinghai Tibet Plateau(82°50¢E - 105°5¢E, 29°40¢N - 38°10¢N)
Sichuan
Yunnan-loess plateau ecological barrier(99°05¢E - 114°25¢E, 24°10¢N - 38°50¢N)
The southern hill
and mountain belt(103°10¢E - 119°15¢E, 22°45¢N - 27°10¢N)
The northeastern
forest zone(118°48¢E - 134°22¢E, 40°52¢N - 53°34¢N)
|
Year
|
2000-2015 Time
resolution 1 year
|
Spatial resolution
|
1km Data
format tif,
.zip
|
Data size
|
53.8MB (After
compression)
|
Projection coordinate system
|
WGS_1984_Albers
|
Foundations
|
Ministry of Science and Technology of P. R. China (2018YFC0507300);
the Second Tibetan Plateau Scientific Expedition and Research Program (2019QZKK0405);
Natural Science Basic Research Plan of Shaanxi Province(2018JM4016)
|
Data publisher
|
Global Change
Research Data Publishing & Repository, http://www.geodoi.ac.cn
|
Address
|
No. 126, Yanta
Road, Yanta District, Xi’an 710054, China
|
Data sharing policy
|
Data from the Global
Change Research Data Publishing & Repository includes metadata, datasets
(data products), and publications (in this case, in the Journal of Global
Change Data & Discovery). Data sharing policy includes:
(1) Data are openly available and can be free downloaded via
the Internet; (2) End users are encouraged to use Data subject
to citation; (3) Users, who are by definition also value-added service
providers, are welcome to redistribute Data subject to written
permission from the GCdataPR Editorial Office and the issuance of a Data
redistribution license; and (4) If Data are used to compile new
datasets, the ‘ten percent principal’ should be followed such that Data
records utilized should not surpass 10% of the new dataset contents,
while sources should be clearly noted in suitable places in the new dataset[9]
|
Communication and searchable system
|
DOI,DCI,CSCD,WDS/ISC,GEOSS,China GEOSS
|
Where NPP is the net
primary productivity (gC/(m2·a)) of pixel x
at time t, APAR is the photosynthetically
active radiation absorbed by vegetation (MJ/(m2·a)), which is estimated by the total solar radiation
(gC/m2) of SOL and the
absorption ratio of vegetation fraction
of photosynthetically active radiation (FPAR); and εis the efficiency of converting photosynthetically active
radiation into organic carbon (gC/MJ2), which is calculated from the maximum light
energy utilization rate (εmax, taken as 0.389 gC/MJ), temperature
stress (Tε) and water stress (Wε). Finally, the annualNPP is the sum of the NPP of each month in the
same year.
3.3 Technology Route
In this study, we used
remote sensing data, data from China meteorological station and various
products in the project. CASA model based on the principle of light energy utilization
was used to calculate the annual NPP of 1km spatial resolution in national
barrier zone. The technical route is shown in Figure 1. In
CASA model, APAR andεare the most important parameters. As
the driving factor of vegetation photosynthesis, radiation data is determined
by the total solar radiation and FPAR. Secondly, the actual and
potential evapotranspiration of the region were calculated by using the regional
actual evapotranspiration model proposed by Guangsheng Zhou[14]
and the complementary relationship proposed by Boucher[15].And theywere
used to describe the influence of available water conditions of vegetation on ε.
Compared with other models, the parameters of themodel are simple and is more
maneuverable. The influence of temperature on εwas calculated by NDVI
and the optimal temperature derived from monthly average temperature. Finally, APAR
and εwere used as the input factors of CASA model to quantify the annual
NPP of the study area.

Figure 1 Technology routefor development of the
dataset
4 Results
and Assessment
4.1 Data Results
Data NBZ_ NPP_ 1 km_
2000-2015 is the annual NPP of national barrier zonein TIFF format from 2000 to
2015. The spatial resolution is 1 km, the unit is gC/m2, and the
projection coordinate system is WGS_1984_Albers, the total size of compressed
data is 53.8 MB. After decompressing, the data can be applied in ArcGIS
software.
The spatial
distribution of NPP at 1 km resolution in 2015 is shown in Figure 2. The national
barrier zonepans about 60 longitudes, and there are obvious differences in climate
between regions, so the spatial distribution of NPP is quite different. In
brief, the spatial distribution of NPP (2015) has the characteristics of high
in the southeast and low in the northwest, with data range from
0-1004 gC/m2. The highest NPP was found in the southern hill
and mountain belt, followed by the ecological barrier of the Qinghai Tibet
Plateau, the northeastern forest zone and Sichuan Yunnan-loess plateau
ecological barrier, and the lowest NPP was found in the northern sand belt.
During the study period, NPP showed a slight upward trend (p=0.96).
During the study
period, the spatial variation of NPP in different regions was quite different.It
shows a significant increase trend in Sichuan Yunnan-loess plateau ecological
barrier and the northern sand belt (p<0.05), with an annual increase of
2.37 gC/m2 and 1.25 gC/m2, respectively;
however, in the northeastern forest zone, it shows a significant decrease trend
(p<0.05), with
an annual decrease of 2.23 gC/m2.And there was no significant
change of NPP in other areas.

Figure 2 National
ecological barrier zone 1 km resolution NPP data (2015)
4.2 AccuracyAssessment

In order to verify the accuracy of NPP dataset, we have carried out
the verification data collection in the paper. The validation data is from NASA
(http://ladswed.nascom.nasa.gov/), andMODIS17A3 NPP data in 2000, 2005, 2010
and 2015 were selected. MRT (Modis Reprojection Tool) software was used to
transform and calculate data. Each year, 54 data points were randomly collected,
with a total of 270 NPP values, which were compared with the results of NPP
data calculated in corresponding years in this paper (Figure 3). The results
show that the difference between them was small (validation data range is
0-1521.6 gC/m2, simulation data range is 0-1004.0 gC/m2),
the average deviationwas about 260 gC/m2,
and the overall accuracy (1 minus RMSE divided by the average value of NPP
simulation data) was 81.47%. It can be seen from Figure 3 that the correlation
between the validation value and the simulation value is high (R2=0.94).
Therefore, the NPP data obtained under the technical process of this paper have
high accuracy, which can accurately reflect the change trend of NPP in national
barrier zonein recent years from a macro perspective.
5 Conclusion
In order to construct the NPP time series product of
national barrier zone, based on the data of remote sensing, meteorology and
soil type to obtain photosynthetically active radiation (APAR) andactual
light energy utilization rate (ε), a modeling study of NPP was carried
out. Compared
with the existing similar products, the dataset has high accuracy and can meet
the design objectives. The net primary productivitydataset of national barrier
zonewith 1 km spatial resolution from 2000 to 2015 shows the spatial
distribution of NPP in different periods. It is helpful to study the ecosystem
service function under the background of global change and analyze the
evolution of spatiotemporal pattern of carbon cycle in national ecological barrier
area. The dataset can provide reliable basic data and information for
comprehensive understanding and grasping the security situation of national
ecological barrier area and sustainable development of ecosystem.
Author
Contributions
Wang,
X. F. designed the overall dataset development, designed the model and algorithm,
did the data validation and wrote this data paper, Wang, Y. collected and processed
the NPP data and wrote this data paper, Yin, L. C. collected and processed the
NPP data.
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