**3. Objectives**

As will be described in more detail in Sections 5 and 6 below, infield systems in Scandinavia existed from the early Iron Age, more than 2000 years ago, until the 19th century, and during this time-period, several changes took place without altering the infield systems' core components, i.e., enclosed managed semi-natural meadows and crop fields, and outland grazing by livestock. As a first reflection, it may seem obvious that this farming system was a way to: "( ... ) engineer environments in ways that enhance the productivity and predictability of economically important species" [33] p. 326. However, an essential feature of niche construction is reciprocal causation, that the processes changing the culture and the environment are mutually influencing each other. This would, for example, be manifested as a response of culture to the altered environment, in turn leading to new alterations in the environment, in turn leading to responses in culture, and so on. Our main objective is to examine whether this was the case. In order to do this, we first need to identify the most important changes in infield systems, from their origin to their end.

Thus, we ask two main questions: (1) Which were the key phases of transitions and change of domesticated landscapes with infield systems? (2) To what extent were these transitions and changes the result of niche construction, involving reciprocal causation between cultural features (e.g., managemen<sup>t</sup> and how landscapes were perceived and organized), and features of the environment and landscape?

### **4. Some Remarks on Approach and Terminology**

### *4.1. A Retrospective Approach*

One methodological problem in historical ecology is how to examine land use far back in time, before we have access to written sources and maps. This study extends back to the early Iron Age, more than 2000 years ago. There are few written sources from Scandinavia before the 13th and 14th centuries AD (except from rune stones, raised from the 4th century onwards, with a particularly intensive phase in the 11th century). More extensive information regarding land use is not available before the 17th century, when cadastral maps (with associated information) were produced. Before that time, and certainly for the first millennium AD, interpretations are based mainly on material evidence such as remains of settlements, field systems, stone walls, etc. Pollen analyses contribute important information regarding general aspects of vegetation such as landscape openness and diversity, e.g., [39,40], and macrofossils contribute information on crops, e.g., [41], but information about the way people shaped and managed domesticated landscapes remains quite vague, e.g., [42]. Furthermore, the mind-set of people, such as conceptions on property and rights to use land, and how people understood the ecological mechanisms behind different kinds of management, for example manuring of crop fields, are mostly beyond reach for us. Thus, when examining how land use affected the landscape and vegetation before we have direct evidence, and the rationale for people's decisions, a few assumptions are needed. Firstly, it was assumed that historical effects of land use such as livestock grazing and production of fodder (hay, and leaf-hay) were similar to the effects we have knowledge about from recent times. A similar assumption was used for conceptions of ownership and land rights, as they have been interpreted based on the earliest written sources, e.g., [43]. Secondly, it was assumed that people behaved rationally, i.e., the way people used land (fields, meadows, pastures, etc.) was rational from the viewpoint of promoting productivity and securing subsistence, as far as that could be achieved within the frames of the material conditions (vegetation, crops and livestock, buildings, tools, etc.) available at that time. Taken together, these assumptions reflect a kind of retrospective approach to historical ecology.
