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Exploration for, and utilization of, collections of tropical pasture legumes
Agro-Ecosystems, 2 (1975, published 1976) 309--318
309
© ElsevierScientificPublishing Company, Amsterdam -- Printed in The Netherlands
EXPLORATION FOR, AND UTILIZATION OF, COLLECTIONS OF TROPICAL PASTURE LEGUMES II. T h e P a p a d a k i s s y s t e m o f c l i m a t i c classification a p p l i e d t o testing areas in northern Australia
R. REID, D.M. R Y A N *
and R.L. B U R T
Division of Tropical Crops and Pastures,Davies Laboratory, CSIRO, PrivateMail Bag, Towns rifle,Qld. 4810 (Australia) *Division of Computing Research, CSIR O, Can berra,A. C.T. 2610 (.4ustralia) (Received November 24th, 1975)
ABSTRACT Reid, R., Ryan, D.M. and Burt, R.L., 1976. Exploration for, and utilization of, collections of tropical pasture legumes. II. The Papadakis system of climatic classification applied to testing areas in northern Australia. Agro-Ecosystems, 2: 309--318. The climatic classification devised by Papadakis is described and the problems encountered in its computerisation are explained. Contrary to Papadakis' claim that the system is easy to use, the authors found that the calculations are time consuming and in some instances complicated. The climates of northern Australia were classified and particular attention was paid to predicted moisture regimes, examination of evaporation rates and comparison with actual records. Also the length of the growing season was examined and found to be only partially successful in relation to agriculture but acceptable to pastoral problems. These findings, together with the fact that this method needs only a small amount of readily available meteorological data, suggest that the Papadakis system is of value in reexamining plant distribution.
INTRODUCTION In a p r e v i o u s p u b l i c a t i o n ( B u t t e t al., 1 9 7 6 ) , we h a v e s h o w n t h a t t h e b i o t i c p o t e n t i a l o f l e g u m e s i n t r o d u c e d i n t o t r o p i c a l A u s t r a l i a is r e l a t e d t o t h e t y p e o f c l i m a t e f r o m w h i c h t h e p l a n t s w e r e collected. We h a v e n o t , h o w e v e r , att e m p t e d t o classify t h e s e c l i m a t e s in a w a y w h i c h w o u l d e n a b l e t h e r e a d e r t o e x t r a p o l a t e t o o t h e r t r o p i c a l areas. T o d o this it is n e c e s s a r y t o classify c l i m a t e s in a w a y w h i c h is o f value f o r p l a n t i n t r o d u c t i o n p u r p o s e s . S u c h a classification m u s t , o f n e c e s s i t y , utilize o n l y t h e r e l a t i v e l y small a m o u n t o f i n f o r m a t i o n w h i c h is generally available f o r t h e s e areas. I t w o u l d a p p e a r t h a t m a n y o f t h e s y s t e m s o f classification w h i c h are available d o n o t m e e t t h e s e t w o r e q u i r e m e n t s . P r o b a b l y t h e closest
310 approximation is that provided by Papadakis (see, for instance, Reid, 1973; Henry, 1970). We have accordingly developed a computer program which enables us to classify climates using this system and herein present the results for northern Australia. For comparative purposes on a world scale the reader is referred to Papadakis (1961, 1966, 1970). We begin by describing the Papadakis system and problems which we encountered in its computerisation. We then compare the results with those obtained by other methods, particularly with that used to survey the resources of northern Australia. Sites referred to in the previous publication (Butt et al., 1976) are located and comparisons made with areas overseas. THE PAPADAKIS CLASSIFICATION The climatic classifications devised by Papadakis (1961, 1966) are examples of the type of system which attempts to avoid the lack of precision in climatological classifications by establishing smaller geographical units offering a large climatic uniformity and more exactly defined agricultural suitability by reason of their smallness. Papadakis states t h a t the classifications differ from other climatic classifications such as t h a t developed by T h o m t h w a i t e , in that the criteria for the definition and delineation of the climatic regions are those on which crops depend. As a consequence of this choice the limits of climatic regions coincide with certain crops. In the work published in 1961 and modified in 1966, Papadakis established 13 degrees of winter severity and 13 degrees of intensity of summer; he selected 40 different temperature regimes from all the combinations possible as TABLE I Class structure Major climatic classes 1. 2. 3. 4. 5.
Tropical Tierra Fria Desertic Subtropical Pampean
6. 7. 8. 9. 10.
Mediterranean Marine Humid Continental Steppe Polar/Alpine
Subdivision of 1. Tropical 1.1 1.2
1.3
Humid semi-hot equatorial Humid semi-hot tropical 1.2.1 Ever humid 1.2.2 Humid 1.2.3 Moist monsoon (1--3 dry months) 1.2.4 Moist monsoon (4 or more dry months) 1.2.4.1 7 humid months 1.2.4.2 6 humid months Dry semi-hot tropical
311
being agriculturally meaningful. He further established 14 regimes of humidity defined by a hydric index and annual distribution. The particular combinations of thermal regime and humidity regime distinguish climatic types, which are numbered decimally in ten major classes, each of which is further subdivided into four or more sub-classes. Papadakis claims that the only meteorological data necessary to allow a site to be classified are the average dally minimum temperature, average of the lowest each month and rainfall, all on a monthly basis. Papadakis (1966) has suggested and worked out potential evapotranspiration by means of a very simple formula. In this he proposes E = E T P = O. 5625(Erna--Erni--2); where E is described as monthly evaporation in centimetres, Erna is the saturation vapour pressure corresponding to the average daily maximum in millibars and Erni--2 is the saturation vapour pressure corresponding to the average daily minimum minus 2 centigrades in millibars. With this formula the only data necessary to calculate evaporation are average monthly maximum and average monthly minimum temperatures. Hariharan (1965) suggested that the Papadakis formula would give an adequate estimate of evaporation from a water surface except in coastal or very humid areas. THE CLASSIFICATION PROCESS
Because of the apparent simplicity of data required for classification and the seemingly valuable comparisons that could be made, we proceeded to classify a number of sites in northern Australia in order to examine and compare the resultant homologues. Contrary to Papadakis' claim that the system is easy to use, we found that the calculations are time consuming and in some instances complicated. This is especially so when once the classification is completed, a further 189 special conditions need to be consulted, in order to specify to which group a particular site belongs. In order to hasten the classification process, we wrote a computer program to examine the data. The program was written in FORTRAN in a DEC system-10 and details are available on request. There were two defects in the classificatory system encountered in the programming. Firstly there were some imprecise statements pertaining to the boundaries of the class limits, and this was particularly marked in the definition of winter type. These limits were standardised throughout according to the pattern followed by Papadakis from his precise class limits. Secondly the table Papadakis recommends for allocating categories was re-ordered on the basis of winter, summer and humidity types to facilitate search procedure. APPLICATION TO NORTHERN AUSTRALIA
Evaporation
It is generally accepted, and was shown in our earlier studies (Butt et al., 1976) that moisture regime rather than temperatures limits the use of various
146 211 111 266 203 276 173 220 160 270 243 224 273 146 303 140 183 161 221 120 300 120 165 183
Brisbane Broome Cairns Charleville Charters Towers Cloncurry Daiby Daly Waters Darwin Hall's Creek Hughenden Katherine Longreach Mackay Marble Bar Mapoon Normanton Rockhampton Roma South Johnstone Tennant Creek Thursday Island Townsville Wyndham
71 160 75 90 113 155 68 166 173 163 125 163 110 85 148 96 146 85 71 75 155 83 96 166
3
(mm)
(mm)
2
Mean winter evaporation Bureau of Meteorology estimate
Mean summer evaporation Bureau of Meteorology estimate
1
Stations
Comparison of summer and winter evapotranspiration values
TABLE II
96 106 93 240 173 250 160 206 113 287 220 190 243 90 336 126 156 133 206 120 260 76 95 166
4
Mean summer evapotranspiration computed from Papadakis (mm)
66 130 66 90 113 136 76 170 128 143 123 163 110 63 153 103 150 90 90 83 140 73 90 163
5
Mean winter evapotranspiration computed from Papadakis (mm)
34 49 16 9 14 9 7 6 20 6 9 15 10 38 9 10 14 17 6 0 13 36 42 9
6
2 and 4
Percentage difference between
7 18 12 0 0 12 10 2 26 12 1 0 0 25 3 6 2 5 21 8 9 12 6 1
3 and 5
t~
~o
313
pasture species in the tropics. We recognise that low temperatures may be important in high altitude tropics or sub-tropical regions. We have therefore paid particular attention to predicted moisture regimes when comparing the various methods of climatic classification. As records of measurement of evaporation in the region are few, estimates of average evaporation rates have been made from maps of average evaporation prepared by the Bureau of Meteorology (1968). These maps were based on records of saturation vapour deficit using the Waite formula and modified by reference to actual records where available. Values of the summer and winter evaporation obtained from this source are compared with those obtained by the use of the Papadakis formula in Table II. The percentage differences between the estimated evaporation values and the values calculated using the formula are also given in Table II. Thesedata show that the values computed using the Papadakis formula agree reasonably well with what may be expected from climatological considerations except in coastal situations and are overall better in winter than in summer. Growing season
The values computed using the Papadakis system are compared with the estimates published by Slatyer and Christian (1954), Fitzpatrick and Arnold (1964) and Slatyer (1964, 1970) in Table III.The application of Papadakis' TABLE III
Growing season values
1 2 3 4 5 6 7 8 9 10 11 * t ** tt
Broome Cloncurry Croydon Daly Waters Hall's Creek Hughenden Katherine Mt. Surprise Normanton Tennant Creek Wyndham
* t t ** * t * t t tt *
Estimated agricultural growth period (Weeks)
Estimated pastoral growth period (Weeks)
Papadakis number of humid weeks
Papadakis number of humid and intermediate weeks
12.0 4.2 12.8 10.7 5.6 6.8 20.2 19.3 6.9 3.5 14.1
16.2 9.0 17.3 14.8 10.3 14.5 22.4 22.5 20.9 6.7 18.2
8 0 8 0 0 0 8 8 8 0 8
28 8 16 12 4 16 20 20 28 4 16
Fitzpatrick and Arnold (1964) Slatyer (1964) Slatyer (1970) Slatyer and Christian (1954)
314
2a
4
26 24
Popodokis No
of
20 18 16
humid &
14
intermediate
I2
( weeks )
I0 8 6 4 2
6 ~ ~ ~
/
/
e
•
e
A ""
•
2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 Estimated
pasloral growth (weeks}
Fig. 1. Relationship between Papadakis'humid and intermediate period and estimated pastoral growth period. classification to the length of the growing season is only partially successful in relation to agriculture. However, when related to the pastoral environment, apart from Broome and Normanton, the correspondence between the two estimates is good but differs constantly by approximately 2 weeks. This is particularly evident in Zone A where pasture improvement may be envisaged, but in Zone B, which may be termed extensive rangeland, there is much more deviation. Here Papadakis defines a humid m o n t h as one when rainfall exceeds potential evapotranspiration and an intermediate m o n t h when rainfall covers more than 50% of the potential evapotranspiration. It should again be noted that in coastal sites the system clearly over-estimates the length of the growing season.
COMPARISON WITH THORNTHWAITE In comparison with the established classification of Thornthwaite (Fig. 2) the Papadakis classification (Fig.3) seemingly presents a more realistic picture of the agricultural climates of northern Australia. The major areas of difference are the East Kimberley region of Western Australia where agronomists have long recognised the semi-aridity of the area which is contrary to the impression that may be gained from the Thornthwaite map. Likewise Papadakis delimits an equatorial climate in Northern Cape York. The Papadakis system b y ~its use of more humidity regimes than the Thornthwaite system is considerably more specific in its class description. Thus where Thornthwaite describes a region in terms of its general water availability, i.e., with a season of great deficiency, Papadakis describes a region in terms of the numbers of humid and dry months.
Subhumid climate Semi arid climate
Arid
= =
=
= = =
C D
E
d r w
0
SCALE
200 }on
Fig. 2. North Australian climates according to Thornthwaite's system from Gentilli (1948).
Moisture deficiency in every season Good moisture in every season Great moisture deficiency in winter
climate
Humid climate Warm climate
= =
B B'
Superh~mid climate Hot climate
= =
A A'
EB '
EA'
DA'd
DA'w
CA'w
CA'w
DB'd
AB '
CB'd
BB'r
CB'r
BB'r
O~
O~
3.14
3.26
1.915 1.916
1.917
i. 54
484
Humid semi-hot equatorial (5 humid months) Humid semi-hot tropical (1-3 dry months) Dry semi-hot tropical (4-5 dry months) Hot tropical (5 or m o r e dry months) " (4-5 dry months) " " (5 humid months) " " (4 humid months) " (3 humid months) S e m i - a r i d tropical (2 humid months) (no humid months) (i or more humid months) Cool winter hot tropical (3 humid months) (2 humid months) (i humid month) Hot tropical d e s e r t Hot s u b - t r o p i c a l d e s e r t Humid sub-tropical Dry m o n s o o n s u b - t r o p i c a l Semi arid m o n s o o n sub-tropical C o n t i n e n t a l sub-tropical Hot s e m i - t r o p i c a l (no humid month) Hot s e m i - t r o p i c a l (i or m o r e humid months)
KEY TO F I G U R E 3 1.143 1.23 1.36 1.42 1.462 1.483 1.484 1.485 1.533 1.54 1.57 1.915 1.916 1.917 3.14 3.26 4.1 4.21 4.22 4.24 4.31 4.32
Fig.3. North Australian climates according to the Papadakis' system.
..23
200 km
4.43
9utn J o h n s t o n e
1.36
4.22
Charte] Towers
'143
Heathlands 1.46~
4.31
0 L
Bay
4.44
O~ ~a 0%
317
CONCLUSION A major criticism of the Papadakis system of classification must be his reference to cultivated species, for to draw conclusions a b o u t the possible distribution of a particular species b y reference to the distribution of one or more other cultivated species may be dangerous. One can observe that a cultivated species m a y often be encountered within the area of distribution of another species b u t one need n o t infer that the o p t i m u m areas for cultivation and the limits of the economic cultivation areas of t w o species need necessarily coincide in all parts of a region or in all parts of the world. In studying the distribution of particular crops it is necessary to k n o w that the crop is a genetic entity. For example, groundnuts are grown under a very wide range of climatic conditions, b u t the cultivated species contain two morphological forms or sub-species which are adapted to high and low rainfall conditions respectively because the characteristic lengths of their growing season are different. Wheat, sorghum, rice and c o t t o n are all used by Papadakis as indicator species, b u t these consist of many hundreds of varieties of different adaptation. It is very difficult to make simple statements a b o u t the climatic limits of the distribution of such genetically diverse crops. We must therefore accept the fact that the Papadakis system is n o t entirely suitable for our present purpose, the meaningful distribution of tropical pasture legumes (see also Reid, 1973). This m e t h o d does, however, produce results which coincide with those of agricultural surveys carried o u t in Australia and the latter are known to be of value. We find, moreover (see Burr and Reid, 1976) that world classifications using the Papadakis system are of value for plant introduction purposes. These findings, together with the fact that this method needs only a small a m o u n t of readily available routine meteorological data, suggest that the Papadakis system is of value in refining the present methods for describing plant distribution. ACKNOWLEDGMENTS We wish to thank Dr. R.L. McCown, C.S.I.R.O. Division of Tropical Agronomy, Townsville, for his advice and encouragement during the work.
REFERENCES Bureau of Meteorology, 1968. Monthly Rainfall and Evaporation. Part 2. Bur. Meteorol., Melbourne, Vict., mimeographed. Burt, R.L. and Reid, R., 1976. Exploration for, and utilization of, collections of tropical pasture legumes. IIL The distribution of various Stylosanthes species with respect to climate and phytogeographic regions. Agro-Ecosystems, 2: 319--327. Burt, R.L., Reid, R. and Williams, W.T., 1976. Exploration for, and utilization of, collections of tropical pasture legumes. I. The relationship between agronomic performance and climate of origin of introduced Stylosanthes spp. Agro-Ecosystems, 2: 293--307.
318
Fitzpatrick, E.A. and Arnold, J.M., 1964. Climate of the West Kimberley area. C.S.I.R.O. Aust. Land Res. Ser. No. 9: 76--102. Gentilli, J., 1948. Two climatic systems applied to Australia. Aust. J. Sci., 11: 13--16. Hariharan, P.S., 1965. Potential evapotranspiration in India. Indian J. Agron., 11: 329--334. Henry, J.M., 1970. The development of agrobioclimatic techniques. In: O.H. Frankel and E. Bennet (Editors), Genetic Resources in Plants - - Their Exploration and Conservation. Blackwell Scientific Publications, Oxford. Papadakis, J., 1961. Climatic Tables of the World. Edited by the author, Av. Cordoba 4564, Buenos Aires. Papadakis, J., 1966. Climates of the World and their Agricultural Potentialities. Edited by the author, Av. Cordoba 4564, Buenos Aires. Papadakis, J., 1970. Climates of the World. Edited by the author, Av. Cordoba 4564, Buenos Aires. Reid, R., 1973. A numerical classification of sown pasture regions based on the performance of sown pasture species. Trop. Grassl., 7: 331--340. Slatyer, R.O., 1964. Climate of the Leichhardt-Gilbert area. C.S.I.R.O. Aust. Land Res. Ser. No. 11: 90--104. Siatyer, R.O., 1970. Climate of the Ord-Victoria area. C.S.I.R.O. Land Res. Set. No. 29: 62--74. Slatyer, R.O., and Christian, C.S., 1954. Climate of the Barkly Region. C.S.LR.O. Land Res. Set. No. 3: 17--28.
309
© ElsevierScientificPublishing Company, Amsterdam -- Printed in The Netherlands
EXPLORATION FOR, AND UTILIZATION OF, COLLECTIONS OF TROPICAL PASTURE LEGUMES II. T h e P a p a d a k i s s y s t e m o f c l i m a t i c classification a p p l i e d t o testing areas in northern Australia
R. REID, D.M. R Y A N *
and R.L. B U R T
Division of Tropical Crops and Pastures,Davies Laboratory, CSIRO, PrivateMail Bag, Towns rifle,Qld. 4810 (Australia) *Division of Computing Research, CSIR O, Can berra,A. C.T. 2610 (.4ustralia) (Received November 24th, 1975)
ABSTRACT Reid, R., Ryan, D.M. and Burt, R.L., 1976. Exploration for, and utilization of, collections of tropical pasture legumes. II. The Papadakis system of climatic classification applied to testing areas in northern Australia. Agro-Ecosystems, 2: 309--318. The climatic classification devised by Papadakis is described and the problems encountered in its computerisation are explained. Contrary to Papadakis' claim that the system is easy to use, the authors found that the calculations are time consuming and in some instances complicated. The climates of northern Australia were classified and particular attention was paid to predicted moisture regimes, examination of evaporation rates and comparison with actual records. Also the length of the growing season was examined and found to be only partially successful in relation to agriculture but acceptable to pastoral problems. These findings, together with the fact that this method needs only a small amount of readily available meteorological data, suggest that the Papadakis system is of value in reexamining plant distribution.
INTRODUCTION In a p r e v i o u s p u b l i c a t i o n ( B u t t e t al., 1 9 7 6 ) , we h a v e s h o w n t h a t t h e b i o t i c p o t e n t i a l o f l e g u m e s i n t r o d u c e d i n t o t r o p i c a l A u s t r a l i a is r e l a t e d t o t h e t y p e o f c l i m a t e f r o m w h i c h t h e p l a n t s w e r e collected. We h a v e n o t , h o w e v e r , att e m p t e d t o classify t h e s e c l i m a t e s in a w a y w h i c h w o u l d e n a b l e t h e r e a d e r t o e x t r a p o l a t e t o o t h e r t r o p i c a l areas. T o d o this it is n e c e s s a r y t o classify c l i m a t e s in a w a y w h i c h is o f value f o r p l a n t i n t r o d u c t i o n p u r p o s e s . S u c h a classification m u s t , o f n e c e s s i t y , utilize o n l y t h e r e l a t i v e l y small a m o u n t o f i n f o r m a t i o n w h i c h is generally available f o r t h e s e areas. I t w o u l d a p p e a r t h a t m a n y o f t h e s y s t e m s o f classification w h i c h are available d o n o t m e e t t h e s e t w o r e q u i r e m e n t s . P r o b a b l y t h e closest
310 approximation is that provided by Papadakis (see, for instance, Reid, 1973; Henry, 1970). We have accordingly developed a computer program which enables us to classify climates using this system and herein present the results for northern Australia. For comparative purposes on a world scale the reader is referred to Papadakis (1961, 1966, 1970). We begin by describing the Papadakis system and problems which we encountered in its computerisation. We then compare the results with those obtained by other methods, particularly with that used to survey the resources of northern Australia. Sites referred to in the previous publication (Butt et al., 1976) are located and comparisons made with areas overseas. THE PAPADAKIS CLASSIFICATION The climatic classifications devised by Papadakis (1961, 1966) are examples of the type of system which attempts to avoid the lack of precision in climatological classifications by establishing smaller geographical units offering a large climatic uniformity and more exactly defined agricultural suitability by reason of their smallness. Papadakis states t h a t the classifications differ from other climatic classifications such as t h a t developed by T h o m t h w a i t e , in that the criteria for the definition and delineation of the climatic regions are those on which crops depend. As a consequence of this choice the limits of climatic regions coincide with certain crops. In the work published in 1961 and modified in 1966, Papadakis established 13 degrees of winter severity and 13 degrees of intensity of summer; he selected 40 different temperature regimes from all the combinations possible as TABLE I Class structure Major climatic classes 1. 2. 3. 4. 5.
Tropical Tierra Fria Desertic Subtropical Pampean
6. 7. 8. 9. 10.
Mediterranean Marine Humid Continental Steppe Polar/Alpine
Subdivision of 1. Tropical 1.1 1.2
1.3
Humid semi-hot equatorial Humid semi-hot tropical 1.2.1 Ever humid 1.2.2 Humid 1.2.3 Moist monsoon (1--3 dry months) 1.2.4 Moist monsoon (4 or more dry months) 1.2.4.1 7 humid months 1.2.4.2 6 humid months Dry semi-hot tropical
311
being agriculturally meaningful. He further established 14 regimes of humidity defined by a hydric index and annual distribution. The particular combinations of thermal regime and humidity regime distinguish climatic types, which are numbered decimally in ten major classes, each of which is further subdivided into four or more sub-classes. Papadakis claims that the only meteorological data necessary to allow a site to be classified are the average dally minimum temperature, average of the lowest each month and rainfall, all on a monthly basis. Papadakis (1966) has suggested and worked out potential evapotranspiration by means of a very simple formula. In this he proposes E = E T P = O. 5625(Erna--Erni--2); where E is described as monthly evaporation in centimetres, Erna is the saturation vapour pressure corresponding to the average daily maximum in millibars and Erni--2 is the saturation vapour pressure corresponding to the average daily minimum minus 2 centigrades in millibars. With this formula the only data necessary to calculate evaporation are average monthly maximum and average monthly minimum temperatures. Hariharan (1965) suggested that the Papadakis formula would give an adequate estimate of evaporation from a water surface except in coastal or very humid areas. THE CLASSIFICATION PROCESS
Because of the apparent simplicity of data required for classification and the seemingly valuable comparisons that could be made, we proceeded to classify a number of sites in northern Australia in order to examine and compare the resultant homologues. Contrary to Papadakis' claim that the system is easy to use, we found that the calculations are time consuming and in some instances complicated. This is especially so when once the classification is completed, a further 189 special conditions need to be consulted, in order to specify to which group a particular site belongs. In order to hasten the classification process, we wrote a computer program to examine the data. The program was written in FORTRAN in a DEC system-10 and details are available on request. There were two defects in the classificatory system encountered in the programming. Firstly there were some imprecise statements pertaining to the boundaries of the class limits, and this was particularly marked in the definition of winter type. These limits were standardised throughout according to the pattern followed by Papadakis from his precise class limits. Secondly the table Papadakis recommends for allocating categories was re-ordered on the basis of winter, summer and humidity types to facilitate search procedure. APPLICATION TO NORTHERN AUSTRALIA
Evaporation
It is generally accepted, and was shown in our earlier studies (Butt et al., 1976) that moisture regime rather than temperatures limits the use of various
146 211 111 266 203 276 173 220 160 270 243 224 273 146 303 140 183 161 221 120 300 120 165 183
Brisbane Broome Cairns Charleville Charters Towers Cloncurry Daiby Daly Waters Darwin Hall's Creek Hughenden Katherine Longreach Mackay Marble Bar Mapoon Normanton Rockhampton Roma South Johnstone Tennant Creek Thursday Island Townsville Wyndham
71 160 75 90 113 155 68 166 173 163 125 163 110 85 148 96 146 85 71 75 155 83 96 166
3
(mm)
(mm)
2
Mean winter evaporation Bureau of Meteorology estimate
Mean summer evaporation Bureau of Meteorology estimate
1
Stations
Comparison of summer and winter evapotranspiration values
TABLE II
96 106 93 240 173 250 160 206 113 287 220 190 243 90 336 126 156 133 206 120 260 76 95 166
4
Mean summer evapotranspiration computed from Papadakis (mm)
66 130 66 90 113 136 76 170 128 143 123 163 110 63 153 103 150 90 90 83 140 73 90 163
5
Mean winter evapotranspiration computed from Papadakis (mm)
34 49 16 9 14 9 7 6 20 6 9 15 10 38 9 10 14 17 6 0 13 36 42 9
6
2 and 4
Percentage difference between
7 18 12 0 0 12 10 2 26 12 1 0 0 25 3 6 2 5 21 8 9 12 6 1
3 and 5
t~
~o
313
pasture species in the tropics. We recognise that low temperatures may be important in high altitude tropics or sub-tropical regions. We have therefore paid particular attention to predicted moisture regimes when comparing the various methods of climatic classification. As records of measurement of evaporation in the region are few, estimates of average evaporation rates have been made from maps of average evaporation prepared by the Bureau of Meteorology (1968). These maps were based on records of saturation vapour deficit using the Waite formula and modified by reference to actual records where available. Values of the summer and winter evaporation obtained from this source are compared with those obtained by the use of the Papadakis formula in Table II. The percentage differences between the estimated evaporation values and the values calculated using the formula are also given in Table II. Thesedata show that the values computed using the Papadakis formula agree reasonably well with what may be expected from climatological considerations except in coastal situations and are overall better in winter than in summer. Growing season
The values computed using the Papadakis system are compared with the estimates published by Slatyer and Christian (1954), Fitzpatrick and Arnold (1964) and Slatyer (1964, 1970) in Table III.The application of Papadakis' TABLE III
Growing season values
1 2 3 4 5 6 7 8 9 10 11 * t ** tt
Broome Cloncurry Croydon Daly Waters Hall's Creek Hughenden Katherine Mt. Surprise Normanton Tennant Creek Wyndham
* t t ** * t * t t tt *
Estimated agricultural growth period (Weeks)
Estimated pastoral growth period (Weeks)
Papadakis number of humid weeks
Papadakis number of humid and intermediate weeks
12.0 4.2 12.8 10.7 5.6 6.8 20.2 19.3 6.9 3.5 14.1
16.2 9.0 17.3 14.8 10.3 14.5 22.4 22.5 20.9 6.7 18.2
8 0 8 0 0 0 8 8 8 0 8
28 8 16 12 4 16 20 20 28 4 16
Fitzpatrick and Arnold (1964) Slatyer (1964) Slatyer (1970) Slatyer and Christian (1954)
314
2a
4
26 24
Popodokis No
of
20 18 16
humid &
14
intermediate
I2
( weeks )
I0 8 6 4 2
6 ~ ~ ~
/
/
e
•
e
A ""
•
2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 Estimated
pasloral growth (weeks}
Fig. 1. Relationship between Papadakis'humid and intermediate period and estimated pastoral growth period. classification to the length of the growing season is only partially successful in relation to agriculture. However, when related to the pastoral environment, apart from Broome and Normanton, the correspondence between the two estimates is good but differs constantly by approximately 2 weeks. This is particularly evident in Zone A where pasture improvement may be envisaged, but in Zone B, which may be termed extensive rangeland, there is much more deviation. Here Papadakis defines a humid m o n t h as one when rainfall exceeds potential evapotranspiration and an intermediate m o n t h when rainfall covers more than 50% of the potential evapotranspiration. It should again be noted that in coastal sites the system clearly over-estimates the length of the growing season.
COMPARISON WITH THORNTHWAITE In comparison with the established classification of Thornthwaite (Fig. 2) the Papadakis classification (Fig.3) seemingly presents a more realistic picture of the agricultural climates of northern Australia. The major areas of difference are the East Kimberley region of Western Australia where agronomists have long recognised the semi-aridity of the area which is contrary to the impression that may be gained from the Thornthwaite map. Likewise Papadakis delimits an equatorial climate in Northern Cape York. The Papadakis system b y ~its use of more humidity regimes than the Thornthwaite system is considerably more specific in its class description. Thus where Thornthwaite describes a region in terms of its general water availability, i.e., with a season of great deficiency, Papadakis describes a region in terms of the numbers of humid and dry months.
Subhumid climate Semi arid climate
Arid
= =
=
= = =
C D
E
d r w
0
SCALE
200 }on
Fig. 2. North Australian climates according to Thornthwaite's system from Gentilli (1948).
Moisture deficiency in every season Good moisture in every season Great moisture deficiency in winter
climate
Humid climate Warm climate
= =
B B'
Superh~mid climate Hot climate
= =
A A'
EB '
EA'
DA'd
DA'w
CA'w
CA'w
DB'd
AB '
CB'd
BB'r
CB'r
BB'r
O~
O~
3.14
3.26
1.915 1.916
1.917
i. 54
484
Humid semi-hot equatorial (5 humid months) Humid semi-hot tropical (1-3 dry months) Dry semi-hot tropical (4-5 dry months) Hot tropical (5 or m o r e dry months) " (4-5 dry months) " " (5 humid months) " " (4 humid months) " (3 humid months) S e m i - a r i d tropical (2 humid months) (no humid months) (i or more humid months) Cool winter hot tropical (3 humid months) (2 humid months) (i humid month) Hot tropical d e s e r t Hot s u b - t r o p i c a l d e s e r t Humid sub-tropical Dry m o n s o o n s u b - t r o p i c a l Semi arid m o n s o o n sub-tropical C o n t i n e n t a l sub-tropical Hot s e m i - t r o p i c a l (no humid month) Hot s e m i - t r o p i c a l (i or m o r e humid months)
KEY TO F I G U R E 3 1.143 1.23 1.36 1.42 1.462 1.483 1.484 1.485 1.533 1.54 1.57 1.915 1.916 1.917 3.14 3.26 4.1 4.21 4.22 4.24 4.31 4.32
Fig.3. North Australian climates according to the Papadakis' system.
..23
200 km
4.43
9utn J o h n s t o n e
1.36
4.22
Charte] Towers
'143
Heathlands 1.46~
4.31
0 L
Bay
4.44
O~ ~a 0%
317
CONCLUSION A major criticism of the Papadakis system of classification must be his reference to cultivated species, for to draw conclusions a b o u t the possible distribution of a particular species b y reference to the distribution of one or more other cultivated species may be dangerous. One can observe that a cultivated species m a y often be encountered within the area of distribution of another species b u t one need n o t infer that the o p t i m u m areas for cultivation and the limits of the economic cultivation areas of t w o species need necessarily coincide in all parts of a region or in all parts of the world. In studying the distribution of particular crops it is necessary to k n o w that the crop is a genetic entity. For example, groundnuts are grown under a very wide range of climatic conditions, b u t the cultivated species contain two morphological forms or sub-species which are adapted to high and low rainfall conditions respectively because the characteristic lengths of their growing season are different. Wheat, sorghum, rice and c o t t o n are all used by Papadakis as indicator species, b u t these consist of many hundreds of varieties of different adaptation. It is very difficult to make simple statements a b o u t the climatic limits of the distribution of such genetically diverse crops. We must therefore accept the fact that the Papadakis system is n o t entirely suitable for our present purpose, the meaningful distribution of tropical pasture legumes (see also Reid, 1973). This m e t h o d does, however, produce results which coincide with those of agricultural surveys carried o u t in Australia and the latter are known to be of value. We find, moreover (see Burr and Reid, 1976) that world classifications using the Papadakis system are of value for plant introduction purposes. These findings, together with the fact that this method needs only a small a m o u n t of readily available routine meteorological data, suggest that the Papadakis system is of value in refining the present methods for describing plant distribution. ACKNOWLEDGMENTS We wish to thank Dr. R.L. McCown, C.S.I.R.O. Division of Tropical Agronomy, Townsville, for his advice and encouragement during the work.
REFERENCES Bureau of Meteorology, 1968. Monthly Rainfall and Evaporation. Part 2. Bur. Meteorol., Melbourne, Vict., mimeographed. Burt, R.L. and Reid, R., 1976. Exploration for, and utilization of, collections of tropical pasture legumes. IIL The distribution of various Stylosanthes species with respect to climate and phytogeographic regions. Agro-Ecosystems, 2: 319--327. Burt, R.L., Reid, R. and Williams, W.T., 1976. Exploration for, and utilization of, collections of tropical pasture legumes. I. The relationship between agronomic performance and climate of origin of introduced Stylosanthes spp. Agro-Ecosystems, 2: 293--307.
318
Fitzpatrick, E.A. and Arnold, J.M., 1964. Climate of the West Kimberley area. C.S.I.R.O. Aust. Land Res. Ser. No. 9: 76--102. Gentilli, J., 1948. Two climatic systems applied to Australia. Aust. J. Sci., 11: 13--16. Hariharan, P.S., 1965. Potential evapotranspiration in India. Indian J. Agron., 11: 329--334. Henry, J.M., 1970. The development of agrobioclimatic techniques. In: O.H. Frankel and E. Bennet (Editors), Genetic Resources in Plants - - Their Exploration and Conservation. Blackwell Scientific Publications, Oxford. Papadakis, J., 1961. Climatic Tables of the World. Edited by the author, Av. Cordoba 4564, Buenos Aires. Papadakis, J., 1966. Climates of the World and their Agricultural Potentialities. Edited by the author, Av. Cordoba 4564, Buenos Aires. Papadakis, J., 1970. Climates of the World. Edited by the author, Av. Cordoba 4564, Buenos Aires. Reid, R., 1973. A numerical classification of sown pasture regions based on the performance of sown pasture species. Trop. Grassl., 7: 331--340. Slatyer, R.O., 1964. Climate of the Leichhardt-Gilbert area. C.S.I.R.O. Aust. Land Res. Ser. No. 11: 90--104. Siatyer, R.O., 1970. Climate of the Ord-Victoria area. C.S.I.R.O. Land Res. Set. No. 29: 62--74. Slatyer, R.O., and Christian, C.S., 1954. Climate of the Barkly Region. C.S.LR.O. Land Res. Set. No. 3: 17--28.