New Zealanders take intrusions on their land very personally, as possessiveness and independence are deeply rooted cultural traits.

Psychologist Crispin Garden-Webster, who specialises in organisational and industrial fields, said New Zealanders were typically individualistic people and responded to intruders on our land - even legal ones - with a lot of emotion.

"It is not just a land thing - there is a sense of being wronged and not being in control of what they think is their own. That creates an emotional response.

"We are very proud of ownership, and a very individualistic community.

"There is a clear distinction between here and some European or Asian countries which are much more collective, and where there are much lower expectations that you'll be able to do what you like."

He said our fierce defensiveness over property could be traced back to 19th century settlers, as people crossed the world to forge independent, frontier lives in a new land.

"New Zealanders who settled in the last 170 years, a lot of them came here to own land and be their own person. Isolation has continued to develop that.

"There is this element of 'we won't be bossed about'."

He said the heavy emphasis on the value of land was echoed in Maori culture.

"The land has both commercial and spiritual value for Maori.

"This can be seen in the coastal marine debate, where they say 'you can use the beach and do what you like with it, but just remember - it's ours'."