Marlborough Sounds Resource Management Plan High wind velocities, especially through the Cook Strait narrows. Gale conditions frequent. Low elevation: 0-560m altitude range; mean altitude 100 m.a.s.l. 3. Water Reasonable water quality as most agricultural farming extensive in nature. Some streams ephemeral, especially during summer months. B. The Biological Environment [Part of Cook Strait Ecological District] Total area of Cook Strait ecosystem 6,659 ha of which; 15% is in native forest and 20% is in shrubland (both native and exotic), 52% is in pasture, native non- woody vegetation; and 13% is in plantation forestry. (Note: Percentages based on interpretation of 1990 satellite images.) 1. Predominant Indigenous Vegetation Detailed in Table 4 Mostly cleared except for some bluff communities and islands. Now in extensive pasture cover. Originally a mixture of broad-leaved forests, especially kohekohe forest, and on exposed, dry, very steep or rocky sites: stunted forest, windshorn scrub and shrublands, tussocklands and herbfields - especially succulents. Compared to other land ecosystems, a high proportion of non-forest communities. 2. Communities and Habitats Island communities nationally important - distinct and rare biotic assemblages; vulnerable to disturbance and loss and difficult to recover. Vital habitat for threatened species due to lack of introduced predators. Several species now confined to Cook Strait ecosystem. Unique animal and plant communities dependent on seabirds - nationally important. Their high fertility/high acid guano input from the marine environment, and major physical effects of burrowing and trampling. Highly productive and high nutrient turnover. Seabirds have a major influence on community composition, structure and processes. Shrublands, herbfields and tussockland communities are highly distinctive - endemic to Cook Strait; important habitats. Eastern flanks of Arapawa Island support some of the best remaining examples of Cook Strait mixed broad-leaved forest - nationally important, especially as possum-free. Frequent swells and surges have a profound influence on coastal communities. Exceptional biodiversity for a maritime land ecosystem. Moderate natural biodiversity relative to other land ecosystems - limited by extreme environmental conditions and narrow range of landforms, altitude, and water regimes. Several otherwise southern and subantarctic species occur here at their northern limits. Lack of introduced freshwater fish. Good fish access from sea but unsuitable in stream habitat due to steep topography and lack of low gradient stream areas. App Two - 26