Mapping regions climatically suitable for particular tree species at the global scale

Forest Ecology and Management, 36 (1990) 47-60

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Elsevier Science Publishers B.V., Amsterdam - - Printed in The Netherlands

Mapping regions climatically suitable for particular tree species at the global scale Trevor H. Booth CSIRO Division of Forestry and Forest Products, P.O. Box 4008, Queen Victoria Terrace, Canberra, A.C.T. 2600 (Australia) (Accepted 19 October 1989)

ABSTRACT Booth, T.H., 1990. Mapping regions climaticallysuitable for particular tree species at the global scale. For. Ecol. Manage., 36: 47-60. A microcomputer program is described which can indicate locations satisfying up to six climatic criteria important for tree species selection. Three of the world's most important plantation species, Eucalyptus grandis, Eucalyptus tereticornis and Pinus radiata are used to demonstrate the program, with assessments being made for over 15 000 locations for each species. The program can assist in checking existing descriptions of climatic requirements. With the aid of explicit methods of analysis or expert advice it can also be used to develop improved descriptions of climatic requirements.

INTRODUCTION

Selecting appropriate species for trial is an important part of plantation establishment. It is a process which will become more difficult if climatic conditions change as a result of the greenhouse effect. In the past, climatic conditions at natural and trial sites were not known accurately. Descriptions of species requirements were largely educated guesses based on known conditions at a few sites and subjective estimates of conditions at many other locations. Recently, new explicit methods of analysis have been developed to describe climatic requirements of tree species (see Booth (1988 ) for summary). These methods make use of modern developments in interpolation, which allow climatic conditions to be estimated reliably for sites which may be some distance from recording stations (Hutchinson, 1984). The methods allow descriptions of climatic requirements to be developed from analysis of both natural and trial sites. To map the results of these studies, as well as previous estimates of requirements, computer programs have been developed which can shown suitable regions at countrywide (Booth et al., 1990) or continental scales (Booth et 0378-1127/90/$03.50

© 1990 Elsevier Science Publishers B.V.

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T,H. BOOTH

al., 1989). The objective of this paper was to complement these methods by providing a means of producing maps at the global scale. The purpose of developing this program was threefold: first, it should provide a rapid means of checking the large number of descriptions of climatic requirements previously published by Webb et al. ( 1984); second, it should allow the checking of descriptions of climatic requirements provided by the explicit means described by Booth et al. (1988); and third, it should allow the quick development of descriptions of climatic requirements based on expert knowledge. METHODS

The WORLD program described here follows the same general structure as the AFRMAP African climatic mapping program (Booth et al., 1989). The program produces a map on a microcomputer screen indicating locations which satisfy specified limits for up to six climatic factors. The six climatic factors used by both the WORLD and AFRMAP programs are as follows: mean annual rainfall (mm); rainfall regime (uniform/bimodal, summer, winter); dry season length (months); mean maximum temperature of hottest month (°C); mean minimum temperature of the coldest month (°C); and mean annual temperature (°C) (see Booth et al., 1989) for detailed definitions). These factors were chosen because they were used by Webb et al. (1984) in their compendium of tree species requirements. They have described the climatic requirements of 173 plantation species, including 52 Australian species. For this demonstration climatic data were obtained from four sources. Interpolated data for 10 187 locations in a half-degree grid across Africa were available from the previous study for Africa (Booth et al., 1989). Interpolated data for 2795 locations in a half-degree grid across Australia were calculated from monthly data previously used by Booth et al. (1986). These monthly values were estimated using interpolation surfaces developed for the BIOCLIM bioclimatic prediction system developed by Nix, Busby and Hutchinson (see Nix, 1986; Busby, 1986; and Hutchinson, 1984). Two data sources were used for areas where interpolated data were not available. Actual data for 2081 locations outside Africa and Australia were derived from the unpublished global climatic database GLOCLIMEANMTH prepared by Nix and McMahon (Centre for Resource and Environmental Studies, Australian National University). Data for a further 328 locations in Brazil, Argentina, Chile and Indonesia were obtained from the FAO (Anonymous, 1985, 1987). Together, these sources provided a good coverage of areas of interest for the introduction of Australian species (Fig. 1 ) Other data could be used by the program if different regions were of interest. The program allows the user to set limits for any combination of the six

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climatic factors. The program then generates a world map indicating areas which satisfy the defined requirements. Green dots on the computer screen are used to show locations which satisfy the requirements, whilst red dots show locations which do not. To allow easy portability and user interaction, the program was written in Turbo Pascal to run on an IBM or compatible microcomputer equipped with an EGA (enhanced graphics adaptor) card and monitor. To allow easy access to the data, the program provides a moveable marker. The computer's arrow keys can be used to move the marker over any of the locations on the screen map. It is then possible to search the database for the information concerning the location. The program clears the map image and lists the name, latitude, longitude and elevation of the selected location, along with the data for the six climatic factors at that location. These are displayed next to the present climatic limits. After the user has inspected the data, the map is restored. The user then has the option to move the marker and look at further data, to modify the climatic limits and redraw the map, or to leave the program. RESULTS Three of the world's most important plantation species were used to demonstrate the use of the program.

Eucalyptus grandis Davidson ( 1988 ) has estimated that over 2.7 × 106 ha of Eucalyptus grandis W. Hill ex Maiden have been established, making it the most important plantation species in the tropics in terms of area planted. The A F R M A P program (Booth et al., 1989 ) clearly demonstrated the weaknesses of the description of climatic requirements Webb et al. (1984) provided for E. grandis. However, a description of climatic requirements produced by the m e t h o d described by Booth et al. (1988 ) produced a much better result. This analysis was intended to show areas in Africa climatically suitable for E. grandis. The following description was obtained from an analysis of 107 natural sites in Australia and 52 trial sites in Africa: mean annual rainfall, 700-2500 mm; rainfall regime, summer/uniform; mean max. temp. hottest month, 25-31 °C; mean min. temp coldest month, 3-12 ° C; and mean annual temp., 14-22 ° C. The above description includes a modification suggested in the discussion by Booth et al. (1988) to increase the lower limit for mean m i n i m u m temperature of the coldest month. This change was made because the lower limit of - 1 ° C observed at a natural site was considerably lower than that observed at any successful plantation site. Only five of the six climatic factors are listed above, because dry-season

GLOBAL MAPPING OF REGIONS CLIMATICALLY SUITABLE FOR TREE SPECIES

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length was not included in the climatic factors analysed by Booth et al. ( 1988 ). The W O R L D program was used to evaluate over 15 000 locations for these five factors; the locations which satisfied the requirements are shown in Fig. 2. The program makes it easy to examine the effects of new information on climatic descriptions. For example, Wang Huoran et al. ( 1988 ) have recently reported a successful E. grandis provenance trial on Hainan Island at a site ( 19 ° 14'N, 110 ° 28' E, 30 m ) considerably warmer than those previously analysed in Africa. The marker facility of the WORLD program was used to determine climatic conditions at a nearby city, Ch'iung Hai (19°25'N, 110 ° 28'E, 37 m ) . Using data from this location, the climatic description was tentatively modified as follows: mean annual rainfall, 700-2500 m m ; rainfall regime, s u m m e r / u n i f o r m ; mean max. temp. hottest month, 25-34°C; mean min. temp. coldest month, 3-16 ° C; and mean annual temperature, 14-25 ° C. The locations shown in Fig. 2 also highlighted a limitation of the climatic description. Three eastern coastal locations north of Florida and three locations around the Gulf of Mexico in the U.S.A. were shown as suitable. Eucalyptus grandis is known to fail in these regions because of occasionally severe frosts (Franklin and Meskimen, 1984). It is not only the degree of these frosts, but their rapid onset, which does not allow the plants to harden, which causes damage (Burgess, 1984; Turnbull and Eldridge, 1984). A fairly complex measure may be needed to describe this risk. Work is underway to determine which m i n i m u m temperature measure could best be added to the Webb et al. (1984) set to account for frost damage in eucalyptus. It is important to determine which factor is the most effective discriminant. Adding another factor to the existing database would be a major task, requiring new interpolation surfaces for Australia and Africa. In the meantime, a simple measure was required. Woodward (1987 ) has shown that absolute (i.e. record) m i n i m u m temperature is useful in defining natural distributions of tree species. Again, on the basis of published data and the limited experience in China, Wang Houran et al. (1988) suggested locations with absolute temperatures below - 8 ° C were unsuitable for E. grandis. This check was made manually for locations in the U.S.A., Europe and China. It would have been desirable to make similar checks for highland areas in southern Brazil, as it was known that some locations, such as Curitiba, may need to be excluded. Unfortunately, the FAO source (Anonymous, 1985), which provided data for the vast majority of locations in Brazil and Argentina, does not include absolute m i n i m u m temperature data. Figure 3 shows the areas which satisfied the revised description (including the result from Hainan Island), but excludes locations in the U.S.A., Europe and China where the absolute m i n i m u m temperature falls below - 8 ° C.

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GLOBAL MAPPING OF REGIONS CLIMATICALLY SUITABLE FOR TREE SPECIES

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Eucalyptus tereticornis Davidson ( 1988 ) identified Tectona grandis L.f. as the second and E. tereticornis Sm. as the third most important plantation species in the tropics. He estimated E. tereticornis had a plantation area of over 780 000 ha in 1980. Webb et al. (1984) used the following description for the climatic requirements of E. tereticornis, based largely on the description of natural distribution conditions presented by the FAO (Anonymous, 1981 ): mean annual rainfall, 500-1500 mm; rainfall regime, summer; dry-season, 4-7 months; mean max. temp. hottest month, 22-32 ° C; mean min. temp. coldest month, 2-12°C; and mean annual temperature, 17-27 °C. Webb et al. (1984) suggested that the above description should be appropriate for the so-called 'Mysore hybrid', which is widely planted in India (Sharma et al., 1986). However, the WORLD program showed no locations in India which satisfied these conditions. So, the opportunity was taken to show how the WORLD program can directly assist in developing improved descriptions of climatic requirements. Professor Lindsay Pryor, an expert on eucalypt introductions, was asked to view the program's output. Using the program's marker facility he was quickly able to examine climatic conditions in areas where he knew E. tereticornis was successful. Modifications to the description were then tried and the results mapped. This iterative procedure was repeated until he was satisfied with the map produced. The following description was obtained in less than half an hour: mean annual rainfall, 500-1500 mm; rainfall regime, summer; dry-season, 4-8 months; mean max. temp. hottest month, 22-42 ° C; mean min. temp. coldest month, 2-19 ° C; and mean annual temperature, 17-27 ° C. Locations which satisfied these requirements are shown in Fig. 4. Pinus radiata With over 3 × l 0 6 ha of plantations around the world, Pinus radiata is the most extensively planted exotic softwood in the temperate zone (Lavery, 1986). The Webb et al. (1984) description of climatic requirements produced no suitable locations in New Zealand, though that country has over one million ha ofP. radiata plantations. Two simple modifications to the description were made on the basis of a bioclimatic analysis of Australian plantations (Booth and McMurtrie, 1988 ). The lower limit of the minimum temperature of the coldest month was reduced from 2 °C to - 2 °C and the lower limit of the dry-season length was reduced from 2 to 0 months. This produced the following description of climatic requirements: mean annual rainfall, 6501600 mm; rainfall regime, winter/hniform; dry-season length, 0-3 months;

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mean max. temp. hottest month, 20-30°C; mean min. temp. coldest months, 2-12 ° C; and mean annual temperature, 11-18 ° C. Locations which satisfied these requirements are shown in Fig. 5. -

DISCUSSION

The reliability of the maps produced by WORLD depends on the accuracy of the climatic description and the coverage of data for a particular area. Suitable locations may be omitted simply because climatic information is not included in the database. For example, E. grandis is grown at Mt. Hagen in Papua New Guinea and E. tereticornis is grown at Matale in Sri Lanka, but these locations were not in the database. Even if a region is represented by a location, the sample locations may miss suitable areas, especially in regions of rugged terrain, where steep temperature and rainfall gradients are to be expected. At least the program's marker facility does allow the exact location (latitude, longitude and elevation) of sample sites to be checked. Information for more locations can be easily added to the database. If necessary, more detailed interpolation surfaces can be developed for regions of particular interest (Booth et al., 1990). Despite these limitations the program provides a rapid means to check the climatic descriptions given by Webb et al. (1984). The analysis of the E. grandis data for Africa had previously shown the weakness of some of these descriptions. The E. tereticornis and P. radiata examples again showed the need to check these descriptions carefully. Though there is a need to improve the climatic descriptions its contains, the compendium by Webb et al. (1984) and the associated INSPIRE expert system program provide a very useful framework. The work presented here suggests that rapid improvements can be made to their climatic descriptions using the WORLD program. The world view of E. grandis suitability (Fig. 3 ) showed major areas climatically suitable for E. grandis in Africa, Brazil, China and (not surprisingly) Australia. The area shown in Brazil was particularly interesting, as extensive trials of eucalypts have been carried out there. No data from Brazilian trials were used to develop the description of requirements. However, the correspondence with areas where E. grandis is the preferred species or where it has at least performed reasonably well in trials was good (see Golfari et al., 1978; Moura, 1980; Anonymous, 1981 ). In addition to indicating areas where E. grandis is of major importance, the revised description identified some relatively isolated areas. For example, about 15 000 ha of E. grandis plantations have been established in Kerala State in southern India (Sharma et al., 1986). In Indonesia, it is being successfully grown near Lake Toba in Sumatra, and in Vietnam it is being grown in southern highland areas (S. Midgley, personal communication, 1989 ). Locations in all these areas are identified in Fig. 3. The analysis of E. grandis also demonstrated the need to add a factor re-

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T.H. BOOTH

lated to frost risk to the six Webb et al. (1984) factors. As they were concerned with species for tropical and subtropical locations, it is perhaps not surprising that they did not place great emphasis on frost measures. However, the work shown here suggests a frost measure would be a useful addition to their six measures. The analysis ofE. tereticornis (Fig. 4) showed how rapid improvements in the descriptions provided by Webb et al. (1984) can be obtained solely on the basis of expert opinion. Most importantly the modified description includes many of the areas of India in which the species or its hybrids are successful (Sharma et al., 1986). It also corresponds well with the areas where it is known to be successful in Brazil (Anonymous, 1981 ). Figure 4 does not show the complete natural distribution ofE. tereticornis in Papua New Guinea, coastal Queensland, New South Wales and Victoria. No climatic data were included for Papua New Guinea (see Fig. 1 ), so no suitable locations could be shown. In the case of Australia, only provenances from northern locations have been important in overseas plantations, so the climatic description only included these areas. Similarly, the analysis of P. radiata showed none of its natural range (see Lavery, 1986), because it has not proved commercially successful under these conditions. However, the WORLD program rapidly showed the limitations of the Webb et al. (1984) description for P. radiata. The modified description (Fig. 5 ) covers the location of the major plantation areas in New Zealand, Australia and South Africa (Lavery, 1986 ). The area of most importance in Chile is also shown, though there were few data points in this region. Similarly, a few points are shown in the Basque region of Spain, where over 250 000 ha of plantations have been established. Parts of Kenya are shown as suitable; there were about 15 000 ha of plantations there until the early 1960s, when needle blight (Dothistroma pini) became a major problem. Several other countries and regions where Lavery (1986) reported encouraging results with P. radiata, such as Argentina, Uruguay, (southeastern) Brazil and France, are also indicated in Fig. 5. Results from relatively well-known species were presented here, so the output of the program could be better judged, However, one of the greatest uses of the program will be in suggesting areas where lesser-known species are worth testing. Publications by Anonymous (1980) and Turnbull ( 1986 ) provide at least partial descriptions of the climatic requirements of many lesser-known species with potential for fuelwood and agroforestry use. Booth et al. (1990) showed how suitable areas in Africa for testing Acacia holosericea could be identified using more detailed analysis. An initial assessment was based solely on a climatic analysis of its natural distribution in Australia. As information becomes available from trials, descriptions of requirements can be improved. The WORLD program may also be used to check and develop improved descriptions of climatic requirements for particular provenances.

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In conclusion, the WORLD program provides a rapid means to check and improve descriptions of climatic requirements of tree species. Whilst the descriptions presented here are considerable improvements over those offered by Webb et al., it is likely that more information from successful sites around the world could be used to improve them further. AVAILABILITY OF PROGRAM

Copies of the WORLD program are available from the author. A nominal charge of US$50 made payable to "Collector of Monies, CSIRO DFFP" covers the cost of floppy disk, handling and airmail postage to anywhere in the world. Any data can be added to the program by the user. The example data for nearly 13 000 locations in Australia and Africa may be purchased for US$100. Enquiries for other example data should be directed to Prof. H.A. Nix (CRES, Australian National University, Canberra, Australia) or Dr. R. Gommes (FAO, Rome, Italy). ACKNOWLEDGMENTS

I wish to thank the following: The Australian Centre for International Agricultural Research for funding part of the work described here; Prof. Henry Nix and Ms. June McMahon for use of data from their GLOCLIMEANMTH database; Prof. Lindsay Prior for his advice in developing an improved climatic description for E. tereticornis; Dr. Ken Eldridge, Dr. Chris Harwood and Mr. Steven Midgley for their helpful comments; the FAO for climatic data; and Ms. Sue Armstrong for technical assistance.

REFERENCES Anonymous, 1980. Firewood Crops. National Academy of Sciences, Washington, DC, 237 pp. Anonymous, 1981. Eucalypts for Planting. Food and Agriculture Organization, Rome, 2nd edn., 677 pp. Anonymous, 1985. Agroclimatological Data for Latin America and the Caribbean (FAO Plant Production and Protection Series No. 24). Food and Agriculture Organization, Rome, 245 pp. Anonymous, 1987. Agroclimatological Data for Asia (FAO Plant Production and Protection Series No. 25 ). Food and Agriculture Organization, Rome, 301 pp. Booth, T.H., 1988. Which wattle where?: selecting Australian acacias for fuelwood plantations. Plants Today, l: 85-90. Booth, T.H. and McMurtrie, R.E., 1988. Climatic change and Pinus radiata plantations in Australia. In: G.I. Pearman (Editor), Greenhouse: Planning for Climate Change. CSIRO, Melbourne, pp. 534-545. Booth, T.H., Nix, H.A., Hutchinson, M.R. and Busby, J.R., 1986. Grid matching: a new method for homoclime analysis. Agric. For. Meteorol., 39:241-55.

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Booth, T.H., Nix, H.A., Hutchinson, M.F. and Jovanovic, T., 1988. Niche analysis and tree species introduction. For. Ecol. Manage., 23: 47-59. Booth, T.H., Stein, J.A., Nix, H.A. and Hutchinson, M.G., 1989. Mapping regions climatically suitable for particular species: an example using Africa. For. Ecol. Manage., 28: 19-31. Booth, T.H., Stein, J.A., Hutchinson, M.F. and Nix, H.A., 1990. Identifying areas within a country climatically suitable for particular tree species: an example using Zimbabwe. Int. Tree Crops J., 6: 1-16. Burgess, I.P., 1984. Tolerance of two years old Eucalyptus grandis and Eucalyptus saligna to winter frost in Canberra. In: Colloque International sur les Eucalyptus resistants au froid, 20-30 September 1983, Bordeaux. IUFRO Proceedings, CSIRO/AFOCEL, Paris, pp. 358366. Busby, J.R., 1986. A bioclimatic analysis of Nothofaguscunninghamii (Hook) Oerst. in southeastern Australia. Aust. J. Ecol., 11: 1-7. Davidson, J., 1988. Breeding eucalypts in tropical countries. In: R.L. Newman (Editor), Proc. International Forestry Conf. Australian Bicentenary, 25 April- 1 May 1988, Albury. Institute of Foresters of Australia, Canberra, Vol. 5, pp. 1-2 l. Franklin, E.C. and Meskimen, G., 1984. Choice of species and provenances in cold summer rainfall climates. In: Colloque International sur les Eucalyptus resistants au froid, 20-30 September 1983, Bordeaux. IUFRO Proceedings, CSIRO/AFOCEL, Paris, pp. 431-357. Golfari, L., Caser, R.L.and Moura, V.P.G., 1978. Zoneamento ecologico esquematico para reflorestamento no Brasil. Centro de Pesquisa Florestal da Regiao do Cerrado, Belo Horizonte, 47 pp. Hutchinson, M.F., 1984. A summary of some surface-fitting and contouring programs for noisy data. CSIRO Division of Mathematics and Statistics/Division of Water and Land Resources, Canberra, Consult. Rep. ACT. 84/6. 24 pp. Lavery, P.B., 1986. Plantation Forestry with Pinus radiata. School of Forestry, University of Canterbury, New Zealand, Rev. Pap. No. 12, 255 pp. Moura, V.P.G., 1980. Avaliacao de especies e procedencias de Eucalyptus em Minas Gerais e Espirito Santo. EMBRAPA, Brasilia, Bol. Pesq. No. 1, 104 pp. Nix, H.A., 1986. A biogeographic analysis of Australian Elapid Snakes. In: R. Longmore (Editor) Atlas of Australian Elapid Snakes. Bureau of Flora and Fauna, Canberra, A.C.T., pp. 415. Sharma, J.K., Nair, C.T.S., Kedharnath, S. and Kondas, S. (Editors), 1986. Eucalypts in India Past, Present and Future. Kerala Forest Research Institute, Peechi, Kerala, 521 pp. Turnbull, J.W., 1986. Multipurpose Australian Trees and Shrubs: I.~sser-known Species for Fuelwood and Agroforestry. Australian Centre for International Agricultural Research, Canberra, A.C.T., Monogr. 1,316 pp. Turnbull, J.W. and Eldridge, K.G., 1984. The natural environment of Eucalyptus as the basis for selecting frost resistant species. In: Colloque International sur les Eucalyptus resistants au froid, 20-30 September 1983, Bordeaux. IUFRO Proceedings, CSIRO/AFOCEL, Paris, pp. 43-62. Wang Huoran, Yan Hong and Zhou Wenlong, 1988. Provenance trials and prediction of suitable planting area based on bioclimatic analysis for Eucalyptus grandis in China. Chinese Acad. For., 1988 Rep., 10:15 pp. Webb, D.B., Wood, P.J., Smith, J.P. and Henman, G.S., 1984. A guide to species selection for tropical and sub-tropical plantations. Commonw. For. Inst. Oxford, Trop. For. Pap. 15:256 PP. Woodward, F.I., 1987. Climate and Plant Distribution. Cambridge University Press, Cambridge, 174 pp. -