Hela Climate & Seasonality

by Dr. Chris Ballard

The valleys of the Central Highlands have been characterised as having circulations of air flow that are significantly independent of larger-scale air movements to the north or south (Brookfield and Hart 1966), resulting in a series of relatively localised climates. But the valleys of the Tari region also lie within a belt of aseasonal climatic conditions that extends along the southern slopes of the Central Range (McAlpine et al. 1983:69-72, Bourke 1988: Fig.2.2) and are thus amongst the few major valleys of the Central Highlands to exhibit marked aseasonality or perennial wetness. Temperature means vary through the day from 13 to 24 degrees centigrade (Figure B8), but the annual range for these maximum and minimum mean temperatures is only about l.S degrees centigrade (Wood 1984: Fig.2.6), a strongly aseasonal condition. Mean annual rainfall for the Tari basin, measured at four stations on the basin floor, is between 2360 mm and 2870 mm (Wood 1984:37). The monthly means taken from the longest record available for the region, at Tari Station, illustrate the lack of a marked dry season (Figure B9) and provide tentative evidence for the double maximum characteristic of the southern slopes of the central cordillera (Fitzpatrick et al. 1966:193), in which monthly rainfall averages appear to peak marginally between February and April and then again between September and November. It should be stressed however that these peaks are neither distinct enough, nor is their occurrence sufficiently consistent between years, to be observed without the aid of long-term records.

There may be some evidence for minor local variation in rainfall within the Tari region, both in mean annual totals, with 3331 mm recorded for Koroba (McAlpine et al. 1983:180), and in the seasonality of rainfall. In a recent reclassification of rainfall seasonality in Papua New Guinea, Abeyasekera (1987) has identified two distinct patterns among the records from the Tari region stations. While the region generally shows an even rainfall distribution throughout the year, Abeyasekera interprets the results of a cluster analysis to reveal a more subtle distinction between the results from Tangi and Koroba on the one hand (Type B 1) and Margarima, Pureni and Tari on the other (Type B2), suggesting that Type B2 patterns exhibit a slight fall in rainfall during June and July that is not evident in Type B 1patterns. In other words, it appears that the double maximum in monthly rainfall decreases from east to west across the Tari region. Mean monthly rainfall at Tari typically exceeds combined estimated evaporation and transpiration, yielding a high water balance estimate (Keig et al. 1979). ¹ This, and the broad uniformity of rainfall over the year, result in consistently high soil moisture storage, a fact that may have been significant historically in the development of the Huli agricultural techniques described in B4.4.

While the term angi (“when”, “time of”) serves broadly to denote recurrent events, such as bai angi (“acorn time”), or specific historic events, as mbingi (mbi: “darkness”; angi: “time”), no terms exist to distinguish amongst seasons nor is there any explicit recognition of annual rainfall cycles. The fundamental significance that seasonality implies for Huli neighbours to the east, such as the Foi (Weiner 1991), Kakoli (Bowers 1968) and Wola/West Mendi (Crittenden 1982), is not evident in Huli life or discourse. are quick to refer to the prolongation of a period of dry or fine (Figure B8), but the annual range for these maximum and minimum mean temperatures is only about l.Sdegrees centigrade (Wood 1984: Fig.2.6), a strongly aseasonal condition.

There may be some evidence for minor local variation in rainfall within the Tari region, both in mean annual totals, with 3331 mm recorded for Koroba (McAlpine et al. 1983:180), and in the seasonality of rainfall. In a recent reclassification of rainfall seasonality in Papua New Guinea, Abeyasekera (1987) has identified two distinct patterns among the records from the Tari region stations. While the region generally shows an even rainfall distribution throughout the year, Abeyasekera interprets the results of a cluster analysis to reveal a more subtle distinction between the results from Tangi and Koroba on the one hand (Type B 1) and Margarima, Pureni and Tari on the other (Type B2), suggesting that Type B2 patterns exhibit a slight fall in rainfall during June and July that is not evident in Type B 1patterns. In other words, it appears that the double maximum in monthly rainfall decreases from east to west across the Tari region. Mean monthly rainfall at Tari typically exceeds combined estimated evaporation and transpiration, yielding a high water balance estimate (Keig et al. 1979) ²

More significant Huli life than the relatively uniform rainfall is the periodicity of annually fruiting trees such as abare (Pandanus conoideus; marita pandanus) and anga (Pandanus julianetti; karuka pandanus), the acorns from the bai (Castanopsis acuminatissima; oak) tree and the appearance of nano (unidentified species) mushrooms, the last being in season through August and September. Pig owners occasionally refer to a bai angi (fruiting of the Castanopsis tree) because their pigs go into the forests to forage for the acorns. ³ For those individuals with either direct ownership of pandanus trees or access to pandanus through kin or affinal ties, the year is to some extent structured by the karuka pandanus harvests, referred to as anga angi (“the time of karuka pandanus”), or anga u lo dawaga (“the time when all call out to cook karuka pandanus”). While pandanus seasonality is poorly understood, with yields appearing to vary considerably between years (Rose 1982), observations of karuka pandanus seasons at six highlands locations suggest that the Tari season, generally over a two-month period between January and March, is not atypical of the highlands as a whole (Bourke 1988: Fig.5.7). In the Southern Highlands region, marita pandanus fruits most heavily between October and April during yielding years, though the season contracts to between January and April at the higher end of the marita range, where most Huli marita trees are located (Bourke n.d.).

It is possible to construct cycles from these seasonal appearances. An older man at Haeapugua, when asked to attempt such a calendar, suggested a cycle running from the period when people begin to succumb to “seasonal” colds (homama), through the combined appearance of nano mushrooms and the new leaves of the poge fig tree (significant because the two are cooked together), to the fruiting of bai, abare (marita) pandanus and anga (karuka) pandanus. As he pointed out, however, poge and abare are virtually continuous phenomena; those without access to poge or abare know when they are in fruit anyway, because they still get homama colds. Certainly no one suggested to me that such a cycle was ever widely employed as a framework for planning, nor does the planting of the major staple crops appear to be seasonally structured, though planting rates obviously vary with perceived short-term changes in soil moisture. ⁴ There are other indicators of seasonality available to Huli, such as the seasonal appearance of migratory birds or the changes in the precise location of the sun’s rise and setting along the mountain ranges. It must therefore be significant in terms of the nature of Huli temporality that, despite this scope for the construction of a notion of seasonality, Huli life is structured around annual cycles.

Longer-term variation in rainfall is more significant in the Tari region than seasonality, and it is the major floods and droughts that figure most prominently in Huli understanding of local climate. The frequency of occurrence of these events is seen to correspond, not to annual climatic cycles, but rather to a longer temporal cycle, monitored through the medium of a sacred geography.

An extract from The Death of a Great Land: Ritual, History and Subsistence Revolution in the Southern Highlands of Papua New Guinea; Australian National University, Cranberra, 1995). pp. 45-48.

(Photo courtesy of Dr. Michael Main.)

1. Prolongation of a period of dry or fine [↩]
2. Wood’s (1984:41) table of monthly evaporation estimates draws on results from nearby Mendi, which has an annual rate broadly similar to that of Tari (Keig et al. 1979:29). [↩]
3. Morren (1979, 1981) has proposed a seasonal rhythm to Miyanmin residence founded on the relationship between the fruiting of certain trees and the movements of wild pigs; this is contested by Bourke’s (1988) criticisms of anthropological uses of data on seasonality generally, and by Gardner (1980, 1981, in prep.) specifically on the question of seasonality in Miyanmin. [↩]
4. This is in marked contrast to the complicated calendar described for the neighbouring Engaspeakers by R.Bulmer (1960b:72), and particularly by Meggitt (1958a), which prompted me to trouble many old men and women at Tari for a comparable scheme. My lack of success in this can perhaps be explained by a personal communication from R.M.Bourke, who assures me that no other researcher in Enga has been able to replicate Meggitt’s calendar and that Meggitt has himself admitted that the calendar owed much to an excess of enthusiasm on his part during early fieldwork. There are also climatic differences between the Enga and Huli regions which lie on opposite sides of the Central Range: Allen’s (1989: Table 2) correlation analysis of rainfall records from stations in the Highlands suggests that the results from the Tari region stations are positively correlated with stations along the southern Papuan coast (Kikori, Itikinumu), but either negatively or not all correlated with station records from central Enga. [↩]