Remapping Tutira: contours in the environmental history of New Zealand

Although members of the first generation of professional geographers in New Zealand identified the ousting of the indigenous plant cover and the partial establishment of an exotic (mainly European) vegetation in its place as an essential theme in the history of that country, and Alfred Crosby made a brief case study of the islands in hisEcological Imperialism, scale problems have made it difficult to develop a microgeographical perspective on the often intricate and incremental processes of environmental transformation. To this end, this paper explores a detailed account of the natural history of a single North Island sheep station written by its owner, W. H. Guthrie Smith, in 1921. By readingTutira, an idiosyncratic but fascinating work, with a geographical eye, the local dimensions of the floral and faunal invasion of New Zealand are revealed. “A record of minute alterations noted on one patch of land” illuminates the biogeographical processes by which New Zealand was transformed and offers insight into an important distinction between ‘natural’ and ‘environmental’ history.     

The assumption of equilibrium in models of migration

In recent articles Evans (1990) and Harrigan and McGregor (1993) (hereafter HM) scrutinized the equilibrium model of migration presented in a 1989 paper by Schachter and Althaus. This model used standard microeconomics to analyze gross interregional migration flows based on the assumption that gross flows are in approximate equilibrium. HM criticized the model as theoretically untenable, while Evans summoned empirical as well as theoretical objections. HM claimed that equilibrium of gross migration flows could be ruled out on theoretical grounds. They argued that the absence of net migration requires that either all regions have equal populations or that unsustainable regional migration propensities must obtain. In fact some moves are inter- and other are intraregional. It does not follow, however, that the number of interregional migrants will be larger for the more populous region. Alternatively, a country could be divided into a large number of small regions that have equal populations. With uniform propensities to move, each of these analytical regions would experience in equilibrium zero net migration. Hence, the condition that net migration equal zero is entirely consistent with unequal distributions of population across regions. The criticisms of Evans were based both on flawed reasoning and on misinterpretation of the results of a number of econometric studies. His reasoning assumed that the existence of demand shifts as found by Goldfarb and Yezer (1987) and Topel (1986) invalidated the equilibrium model. The equilibrium never really obtains exactly, but economic modeling of migration properly begins with a simple equilibrium model of the system. A careful reading of the papers Evans cited in support of his position showed that in fact they affirmed rather than denied the appropriateness of equilibrium modeling. Zero net migration together with nonzero gross migration are not theoretically incompatible with regional heterogeneity of population, wages, or amenities.