Sir Alan helps relocate birds before the opening of the takahe captive rearing area at the Burwood Bush facility, Western Southland, in April, 2013. PHOTO: SUPPLIED : Standing his ground

This drawing by political cartoonist Sid Scales, depicting public opposition to government and business plans to raise the levels of Lakes Manapouri and Te Anau, appeared in the Otago Daily Times on February 5, 1970. The original drawing was later... : Standing his ground

The original Guardians of Lakes Manapouri, Monowai and Te Anau, appointed by then prime minister Norman Kirk in 1973, meet again in 1994 (from left) Wilson Campbell, Prof (later Sir) Alan Mark, John Moore, Jim McFarlane and Les Hutchins. PHOTO: ODT FILES : Standing his ground

Sir Alan (seated, right) listens as members of climate-change youth movement Generation Zero make presentations during the launch of the multifaceted risk assessment campaign Wise Response in March 2013. PHOTO: SUPPLIED : Standing his ground

The way in which Emeritus Professor Sir Alan Mark researched tussock, advocated for its value and consequently shaped the face of New Zealand's upland landscape, is typical of his approach and impact. PHOTO: LINDA ROBERTSON : Standing his ground