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Surveying China's agricultural resources: Patternsand progress from spaceS. A. Morain aa Technology Application Center , University of New Mexico , Albuquerque, NewMexico, 87131, U.S.A.Published online: 17 Sep 2008.

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Surveying China's Agricultural Resources: Patterns andProgress from Space

S. A. MorainTechnology Application CenterUniversity of New MexicoAlbuquerque, New Mexico 87131U.S.A.

Abstract

The creation of an agricultural remote sensing center at Beijing Agricultural University (BAU) and an initialnetwork of participating subcenters located in Harbin, Nanjing, and Chengdu marks the beginning of Chinas effortsto assess, monitor, and tabulate its agricultural production. The Ministry of Agriculture, Animal Husbandry, andFisheries (MAAF) has designated BAU as its lead research and applications center to develop remote sensingtechnologies throughout the six agro-economic zones of the country. Working with United Nations DevelopmentProgramme (UNDP) funding and implemented through the assistance of the United Nations Food and AgricultureOrganization (UN/FAO), the center and subcenters have been staffed, equipped, and trained to inaugurate their ownresearch and development programs in agriculture. Three of their initial activities are described here to alert the scien-tific community to the existing infrastructure and breadth of current interests. These studies include (1) an aerial,small format camera assessment of panda bear habitats in Baoxing County, Sichuan Province; (2) an initial assess-ment of land-use categories in Yixing County, Jiangsu Province, using Landsat MSS data; and (3) a preliminary lookat biomass assessment using geometrically uncorrected AVHRR data of Inner Mongolia. China hopes to expand thesubcenter network to include one in each agro-economic zone and, along with this, to expand the scope of remotesensing technologies and applications.

Introduction

By the end of this century there will be few areas in[the] world where agricultural production can beincreased by expanding the area cultivated. Coun-tries that cannot take advantage of yield-increasingbiological and chemical technology will find itincreasingly difficult to maintain their export earn-ings from agriculture or even to meet their domesticfood needs. Only a country that establishes its ownresearch capacity in agriculture can gain access tothe advances in knowledge that are available to itfrom the global scientific community and embodythat knowledge in the technology suited to its ownresource and cultural endowments.

1983. Science. 222 (4619):11.

This view, by Dr. Ruttan, is particularly thought-provoking when applied to the evolving agricultural envi-ronments of the Peoples Republic of China. As the mostpopulous nation on earth and the third largest in land

area, its ability to produce ever increasing amounts offood and fiber will largely determine the economic futureof its many ethnic peoples, and indeed may well set themood for social and political stability throughout theAsian region, if not the world. There are still vast, poten-tially arable, lands in central and western China, as well asthe prospect for higher yields and greater production inthe densely populated eastern regions of the country,both of which can be realized by using a combination ofexisting land management strategies. The chemical andyield-increasing technologies mentioned by Dr. Ruttan arecritical, of course, but they focus squarely on increasingthe output of individual crops in specific agroecologicalsettings. Remote sensing technologies should also beincluded in his list as the primary means for measuringand monitoring the impact of these crop specifictechnologies at local, regional, and national scales.Changes in agricultural production that are stimulated bychemical and agronomic advancements cannot be

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isolated from those changes stimulated by social policiesthat alter man's use of the land. Mr. Song Jian (1985) has,for example, indicated that the new system of contractedresponsibility that links remuneration to productionincreased small, rural farm production by 24 percent in1984 and accounted for 40 percent of the nationalagricultural output. Large communal farms are beingreplaced by smaller, individually controlled fields. In geog-raphic terms, the spectral and spatial domains of all thesechanges, as they occur through time, can be detected,recorded, and analyzed by aerial and satellite sensors.Chinas science and technology community has recog-nized the importance of monitoring its agricultural situa-tion by remote detectors and accordingly has expandedits research capacity and affiliation with the global scien-tific community to realize these benefits.

Since the early 1980s there has been growing interestin monitoring Chinas natural and cultural resources.Some recent titles indicate the nature of this interest:Agricultural Development in China, Japan, and Korea(1983); Agriculture in Chinas Modern Economic Develop-ment (1983); The Bad Earth: Environmental Degradationin China (1984); and Chinas Changed Road to Develop-ment (1984). Concern over the approaches to resourceinventory, resource conservation, and resource develop-ment has spread rapidly throughout the Chinese scientificand technical communities, mainly spearheaded by theState Science and Technology Commission, by AcademiaSinica, and by cognizant resource Ministries. Among themajor concerns are improved methods for agriculturalproduction, inventorying soil erosion, monitoring refores-tation, protecting natural wildlife areas, and improvingflood hazard prediction.

As is common throughout the developed anddeveloping world, however, resource conflicts are appa-rent. Smil, in The Bad Earth, points out that mistreatmentof the environment may be the fundamental check onChinas reach toward prosperity. China has only abouthalf the forest area of the United States and this area isreceding rapidly. Soil erosion, an historic problem inChina, has been further aggravated in Inner Mongolia bythe government's desire to convert natural grasslands intocropland. In recent years an estimated 170,000 squarekilometers of reclaimed land has been transformed intodesert.

Existing efforts by the World Bank, United NationsDevelopment Programme, FAO, and other internationalbodies are mainly in the form of exchanges of humanresources and joint research projects, many of whichfocus on applied sciences and engineering. In the nameof "technology transfer," these efforts are expanding toaddress a broader range of needs facing the developmentof China's agricultural and natural resources. In China, theneed for basic resource information far exceeds themeans or available money for traditional methods of datacollection. Satellite-based data collection is without ques-

tion the most efficient and least costly means for agricul-tural inventory, mineral and hydrocarbon exploration,forest surveys, wildlife habitat mapping, hydrologicalinvestigations, and general purpose land-use mapping.

China's Agricultural Remote Sensing Network

China's Ministry of Agriculture, Animal Husbandry, andFisheries (MAAF) in cooperation with the United NationsDevelopment Programme (UNDP), the UN Food andAgriculture Organization (FAO), and Beijing AgriculturalUniversity (BAU) have completed a five-year program toestablish a network of remote sensing facilities in four ofthe six agroeconomic zones of the country (Figure 1). Thehub of the network is located at the BAU Center forAgricultural Remote Sensing, with subcenters located inProvincial Agricultural Academies at Harbin, Nanjing, andChengdu. The Center is responsible for training, technicalassistance, and digital image processing for each of thesubcenters, as well as for basic research and applicationsof remote sensing in its own agroeconomic zone. Thesubcenters are also engaged in digital image analysisusing data sets provided by BAU, but they also have amajor involvement in more traditional visual imageinterpretation. Their primary function is to developtechniques for crop yield and production estimation;perform local, provincial, and regional analyses ofresources; and to report general agricultural informationto appropriate government authorities.

Current and Future Applications

Aside from the attendant training programs and equip-ment procurement for this network, a number of agricul-tural and other projects have been undertaken to makepreliminary assessment of satellite monitoring capabilities.Of particular interest are the panda bear habitat studies inBaoxing County, Sichuan Province; the land-use studiesin Yixing County, Jiangsu Province; and the rangemanagement studies near Chifeng in Inner Mongolia.This paper describes the satellite and human resourcesdevoted to these studies and assesses their progress ineconomic and social terms.

The Baoxing County study focuses on small formataerial photographs to measure bamboo resources in thepanda bear sanctuary. Yixing County is in a heavily popu-lated and agriculturally diverse region southeast of Nan-jing. Cropping patterns are changing rapidly because ofthe contract responsibility system and this in turn iscausing changes in overall land use and production.Landsat MSS is the primary data source for monitoringthese changes but coarser resolution AVHRR-LAC dataand, hopefully, finer resolution SPOT data will be incor-porated later. For Inner Mongolia, AVHRR-GAC data will

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Figure 1. National and agroeconomic boundaries of China superimposed on an AVHRR-GAC image obtained in September-October 1984. Also shown are locations for the center and subcenters of the existing Agricultural Remote Sensing Network ofChina (solid dots) and proposed new subcenters (open circles).

be combined with Landsat MSS and aerial photographyto assess biomass changes and soil erosion on the desertmargin.

Habitat Assessment

One of China's most treasured species is the pandabear {Ailuropoda). In an effort to protect its decliningnumbers, the government has set aside the BaoxingCounty Sanctuary which covers an area of 4,950 squarekilometers of inaccessible, mountainous terrain. Becauseof its varied topography, remote location, and sparsepopulation density (about 15 persons/sq. km), there hasnever been a detailed survey of either the vegetationtypes or numbers of panda bears present.

Baoxing County lies in west-central Sichuan Provinceat 102°25' East longitude and 30°09' North latitude. It isabout 61 kilometers from east to west and about 81kilometers north to south. Elevation varies from 750meters to 5,330 meters and local relief ranges between

200 and 400 meters. Vegetation, consisting mainly offorest, pasture, and farmland covers almost 96 per cent ofthe area. It is believed that bamboo, a key resource forpandas, covers about 10 per cent of the sanctuary butthis, admittedly, is nothing but a guess. Among the crucialinputs for a resource survey is a vegetation map atperhaps 1:50,000 scale that can be used as a baseline tomonitor future changes. Such a map could most easily beprepared from large scale aerial photographs andsubsequently digitized into a habitat information systemcontaining other parameters like elevation, slope, aspect,sighting locations, age, sex, and related ecological andphysiological data.

The pandas chief diet consists of bamboo. It occursprimarily in the elevational range from 2,500 to 3,400meters in stands with China fir. Within the sanctuary ittypically forms part of the ground cover synusium and isoverstoried with a mixture of deciduous and coniferousspecies (Betula spp., Acer spp., Abies spp., and Piceaspp.). Since healthy stands of bamboo remain greenthroughout the year, the relatively open (<50 per cent

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closure) overstory permits monitoring during the fall andspring seasons using color infrared photography (Meyer,1985). During April and May, in particular, reflectiveinfrared images should show the evergreen conifers aspurplish-brown, the deciduous trees as bluish-green topale pink (depending upon stand phenology), and thebamboo either as red (if alive) or straw-colored (if dead).Field investigators have noticed, in fact, that bambooregrowth occurs where older bamboo has died (Figure 2),and that it takes about eight years for new bamboo toserve as food for the panda.

As one of its remote sensing applications projects, theChengdu Subcenter for Agricultural Remote Sensinginitiated an aerial survey of the Baoxing CountySanctuary in April 1985. With support from the ChineseAirforce, who provided an Andropov-5 aircraft, and tech-nical assistance from Dr. M. P. Meyer, test flights toacquire 35mm CIR photographs were conducted. Figure3 is a stereo triplet from the flight of 18 April and has ascale .of approximately 1:12,000. These images weretaken with a 50mm lens Canon AE-1 using Kodak 2443

film and a Wratten 12 filter. Shutter speeds were variedalong the flight line between 1/125 and 1/1,000, but thebest results were obtained at 1/500.

In Figure 3, areas of bamboo mixed with other shrubsappear in the more intense red and pink tones in theupper two-thirds of the image, mainly on the west facingslopes. The major zone of occurrence is in the moresteeply sloping land between the floodplain of theJahong Jiang and the ridgeline at the top of the image.Extensive areas of deciduous vegetation occur on thesoutheast slopes, in ravines at lower elevations, and at thehighest elevations on east facing slopes. At this scale,areas of dead bamboo are difficult to reliably identifyunless they are several meters in diameter. Mixtures of liveand dead are nearly impossible to delineate effectively.One likely spot of dead bamboo has been circled at theright side of the triplet.

The flight of April. 18, 1985, confimns the detectabilityof important vegetational resources in the panda bearecology. The next step is to obtain complete small formatphoto coverage of the sanctuary and this is scheduled for

Rgure 2. Aspects of bamboo ecology in Baoxing County Panda Bear Sanctuary.a. Typical appearance of bamboo c. Dead bamboo

b. One year old panda tagged in the Sanctuary

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Rgure 3. Stereo triplet of part of the Baoxing County Panda Bear Sanctuary. Area marked A is healthy bamboo with mixtures ofdeciduous trees; B is bamboo with mixtures of coniferous trees; C is mainly deciduous vegetation without bamboo; and D ispossible dead bamboo.

Fall 1985 and Spring 1986. It is estimated by Meyer(1985) that some 1,500 photographs at 1:30,000 scaleand having 60 per cent sidelap will have to be interpretedto prepare the baseline vegetation map. The author'sopinion is that 1:30,000 images will be too small in scaleto reliably identify areas of dead bamboo. If a larger scaleis selected, then of course many more photographs willhave to be interpreted. Perhaps the better approachwould be to first delineate on topographic maps theecological (elevational) zone between 2,000 and 3,700meters where most of the pandas live, and then concen-trate photo coverage in those areas. Eventually as satellitesystem resolution (both spatial and spectral) improves, itmay be possible to quickly update this vegetationalresource.

Land-Use Assessment

The goal of most agricultural remote sensing programsis to forecast crop yield and crop production. In achievingthis, a wealth of spectral and spatial data are collectedand analyzed that can be used in related contexts likeland-use measurement, natural hazard assessment, land

capability predictions, and general environmentalmonitoring. The social and economic impacts of remotesensing technology are consequently far deeper than theoriginal stimulus behind its adoption. Indeed, remotesensing provides the means for understanding man's rolein both direct and inadvertent alteration of the globalhabitat, and while crop production is one of the most crit-ical results of these physical and chemical manipulations, 'our understanding of the environmental conditions thatultimately signal this outcome will largely determine oursuccess.

In China an important investigation is now underwayby the Remote Sensing Subcenter at Jiangsu AgriculturalAcademy that will assess the land-use patterns in YixingCounty. This area lies in the lake region between Shang-hai and Nanjing and is characterized by five districts: (1)hilly topography in the south that is partly forested andpartly cultivated; (2) plains in the. north; (3) swamps; (4)mountains; and (5) a lakeshore district on the east (Table1). Altogether, there are about 170,000 sq. km of arableland, most of which is devoted to rice and wheat; butthere are other important economic crops like tea,mulberry, vegetables, melons, jute, chestnuts, and rapeseed.

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Table 1

District

Hills

Lakeshore

Swamps

Plains

Mountains

General Economic Districts of Yixing County

Approximate Percentageof County Area •;

25

4

16

40

15

Remarks

60% is forested and has unfavorable crop conditions. Reforestation is underway.' 40% is arable, of which about half is irrigated ; lowest per capita income in

country.

Highest economic diversity (cropping index > 200%); median per capitaincome.

40% of county's rice, wheat, and rape seed production; highest yields; highestflood hazard; low per capita income.

About half of all food production in county; mainly irrigated rice and mulberry;highest per capita income.

Forested mainly in fir and bamboo; economic crops are fuelwood, chestnut, andtea.

Two separate computer classifications have beenperformed on Landsat MSS spectral data for the county.Figure 4A is an analysis using a PDP 11/24 equipped witha DIPIX ARIES II analysis package, and Figure 4B showssimilar results using a VAX 11/750 computer driven by

NASA/ELAS software. In general, the spectral classesidentified in each can be related to economically mean-ingful agroecological environments. For the mountainousarea forests, bamboo, and tea growing can be identifiedas a single unit. The hilly drylands surrounding the moun-

Figure 4. Computer classifications of Yixing County spectral data, (a) Data obtained September, 1981; (b) Data obtainedDecember, 1984.

Legend

Shrub and grass

Water

Building

Forest and bamboo

Orchard

Paddy

Dryland

4 a. Analysis from PDP 11/24 using Dipix ARIES II package and color printer.

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4 b. Analysis from VAX 11/750 using NASA/ELAS packageand printed from color monitor.

tains and scattered throughout the county are measurable,as are the bulk of the paddy lands occupying the plainsand swamps. The lakeshore district is partially classified asorchards.

Figure 5 shows the two-channel spectral distribution oftwenty-two NASA/ELAS classes and their reduction intofive categories; and Table 2 lists the approximate area ofthese categories in hectares. They compare favorably tocomparable classes derived from analysis of Figure 4A.Among the major refinements still needed is to improve

Figure 5. Two-channel spectral plot of twenty-twospectral classes grouped into five land-use categories. Seealso Figure 4b.

identification accuracies for non-agricultural land such asvillages, roads, and the irrigation network; separation andidentification of cultivated and forested lands in the hillyand mountain districts; and separation of wheat and ricecrops. Some of these refinements will require finer spatialresolution as might be provided by Landsat TM (30meter) or French SPOT (20 meter) data, and some willrequire spectral data obtained at different times in thecropping cycle.

Table 2 Approximate Areas(derived from analysis of Landsat

Category

Rice Paddy

Dryland

Orchards

Forest

Grassland/Shrub

of Land-Use Categories in Yixing CountyMSS data obtained December, 1984)

Hectares

121,911

20,388

5,907

17,579

4,545

**Percentages are based on the total area of the listed categories excluding water and "other."

Percentage of County**

71.57

11.97

3.47

10.32

2.67

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Biomass Assessment

Smail (1984), among others, has commented on therapid degradation of land in central China resulting fromthe conversion of natural rangeland into more valuableirrigated agricultural production. Major managementproblems arise from this conversion, however, largely inform of increased soil erosion and salinization. In thelonger term there is concern for human impact on theexpansion of these drylands into the North China Plainfollowing much the same agroeconomic scenario as maybe operating in the American Southwest in the Chihua-huan and Sonoran Deserts. The question of soil erosion isso central to the Chinese food production system that in1984 the Ministry of Water Resources and Electric Powercreated the International Research and Training Centre onErosion and Sedimentation (IRTCES). Together with assis-tance from UNESCO, this Centre will undertake trainingand international technical cooperation to address erosionproblems on some 1.5 million square kilometers ofChinas interior, most of which is located in the loessplateau and in Inner Mongolia.

Strategies for assessing the total environmental impactof land-use conversion vary from (1) those techniquesrequired for measuring soil loss, to (2) those needed toassess the spread and intensity of salt accumulation, and(3) those useful in monitoring seasonal and longer termbiomass patterns. The Agricultural Remote SensingCenter in Beijing has already begun research on adaptingthe Universal Soil Loss (USL) and wind erosion equationsto include satellite spectral measurements in parts ofHebei and Shanxi Provinces; in September 1984, ithosted a one-month training program in Inner Mongoliaon the application of Landsat MSS, NOAA-7 AVHRR,and simulated French SPOT data to biomass changes inthe dryland transitions. Results from this training programare not available for this report but some preliminaryobservations from AVHRR-GAC analysis are shown.

Advanced Very High Resolution Radiometer (AVHRR)data have recently become popular for calculating anormalized difference vegetation index (NDVI) of large

geographic regions. The results of some of these analyses,which are crudely interpreted as an estimator of biomass,are given in Justice, et al. (1985) and Tucker, et al. (1985a, b). NDVI is calculated by using the red and reflectiveinfrared spectral channels (channels 1, 2) of the AVHRR5-channel scanner (see Table 3), either in the global areacoverage (GAC) mode having 4-kilometer spatial resolu-tion or local area coverage (LAC) mode having 1-kilometer resolution resampled from GAC. Figure 1 is ageometrically corrected three week (September-October)average NDVI map of GAC data for all of China, uponwhich the agroeconomic zones have been superimposed.The areas of greatest potential soil erosion are shown inorange, brown, and yellow colors (low biomass) to thenorthwest and west of Beijing and in the greenish colors(medium biomass) northeast of Beijing. Figure 6 is a setof non-geometrically corrected images showing the areanorth of the Gulf of Liaodong, which for reference, is theblack area at the bottom of each image. •

The left image in Figure 6 shows NDVI on June 8,1981; the center image shows conditions on August 6,1981; and the right image shows NDVI on October 12,1981. The color scheme for these three images is theopposite of that in Figure 1, so areas of highest biomassare yellow and red while the lowest values are blue andviolet. Clouds and water are black. There is an obviousand significant increase in NDVI between June andAugust and a phenomenal decrease by October. On theAugust image, the area of greatest interest is the blue-green region toward the center. This is the northeast partof Inner Mongolia around Chifeng bordering Liaoningand Heilongjiang Provinces. The same area is seen onFigure 1 as mottled greens and yellows signifying mediumto low biomass. Enlargements of this area, especially ifLAC rather than GAC data were used, would highlightlocalities of greatest seasonal, annual and decennialchanges. If these values were then correlated withmeteorological data, climatological trends and ground-based biomass measurements, a regional "picture" ofrangeland conditions, and the rates and directions ofpossible desertification, might be pieced together.

Table 3 NOAA-7 AVHRR Spectral Channels and NDVI Strategies

Channel

1

2

3

4

5

Bandwidth (/im)

.58 - .68

.725- 1.10

3.55 - 3.93

10.5 -11.3

11.5 -12.5

NDVI Strategies

Channel 2/Ch 1

or

Ch2 - ChiCh2 + Chi

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(a)

Figure 6. AVHRR/NDVI images for parts of Inner Mongolia, Liaoning, and Heilongjiang Provinces in northern China, (a) June 8,(b) August 6, (c) October 12, 1981.

Conclusions

Agriculture is one of the four priority sectors identifiedby the Chinese Government and within ihis sector theintroduction and use of remote sensing, as an advancednew technology, is recognized as being important tofuture agricultural development. From among the manynations currently exploring the application of remotesensing techniques, the People's Republic of China isperhaps unique in its ability to benefit from the scientificbreakthroughs of the last few years by virture of itsmeasured and reasoned entrance into the technology andbecause of the scientific infrastructure it has built.Successful completion of the projects already underway,

and others yet to be defined, will benefit from the effortsof scientists in other countries through the normalprocesses of scientific publication and technical meetings.Now that most of the basic infrastructure exists for utilizingthe technology, the next appropriate step is to carry outmeaningful demonstrations that have national impact. It isunrealistic to expect Chinas agricultural planningcommunity to adopt remote sensing technology simplybecause a capability for its use has been demonstrated ina few provinces. Agricultural planning around the world istraditionally a very conservative process. Advancedtraining and demonstrations of the technology are essen-tial to convince both the economic and agronomiccommunities that remote sensing can deliver key data andinformation quickly and economically.

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References

Anonymous, Chinas Agricultural Economy, Sheet Number 10in China Current Data Maps, Asian Research Service, HongKong, 1985.

C-M. Hou and T-S. Yu (eds.), Agricultural Development inChina. Japan and Korea, University of Washington Press,Seattle, 1983, 878 pp.

S. Jian, Science, 229(1985) 525-527.C. O. Justice, J. R. Townshend. B. N. Holben, and C. J. Tucker,

International Journal of Remote Sensing, 6(1985) 1271-1318.

N. R. Lardy. Agriculture in China's Modern Economic Development, Cambridge University Press, New York, 1983, 285 pp.

N. Maxwell and B. McFarlane (eds.), China's Changed Road toDevelopment, Pergamon Press, New York, 1984, 256 pp.

M. R Meyer, Panda Bear Habitat Identification, unpublished,UN/FAO Consultant Report on Project CRP 81/045, April29, 1985, 57 pp.

V. W. Ruttan, Science, 222(1983) 11.V. Smil, The Bad Earth: Environmental Degradation in China,

Sharpe, Armonk, New York, 1984, 247 pp.M. Sun, Science, 228(1985) 559-560.C. J. Tucker, J. R. Towshend and T E. Goff, Science,

227(1985a) 369-375.C. J. Tucker, C. L. VanPraet, M. J. Scharman and G. Van

Ittersum, Remote Sensing of Environment 17(1985b) 233-249.

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