providing access to different parts of the core zone. A study of the size of the glaciers in the park, made using Landsat images over the decade 2001 to 2010, shows that the ice cover is substantially unchanged. This demonstrates the fact that the Karakoram region is bucking the trend for glaciers to retreat that is happening elsewhere; this is known as the "Karakoram anomaly". Ecological zones The park has several distinct ecological zones, each with its own natural vegetation which is closely related to the climate and topography; in general, the area has low precipitation and experiences humid westerly winds. The villages are in the valley bottoms where wheat, maize and potatoes are grown, and pomegranate and apricot trees thrive. The lower slopes consist of "alpine dry steppes". They have gravel and moraine soils and support sparse grass and scrub. The "sub-alpine scrub zone" is found beside rivers and streams, in gullies and ravines. It consists of bushes and small deciduous trees and provides browsing for livestock and wild ungulates. Higher up there is the "alpine meadows and alpine scrub zone" which has high pasture and open coniferous forest and is only available for grazing in summer. Above this are permanent snowfields and cold desert areas which occupy the zone, and here there are isolated patches of stunted grass and hardy, low vegetation. Flora and fauna Some valleys are dominated by communities of West Himalayan spruce, Himalayan white pine and Pashtun juniper, including some pure stands of P. smithiana. Smaller shrubs and plants associated with these communities include sea wormwood, Astragalus gilgitensis, Fragaria nubicola, Geranium nepalensis, Kashmir balsam, Thymus linearis, white clover, Rubus irritans, Taraxacum karakorium and Taraxacum affinis. On some east and south-facing slopes, common sea buckthorn is the dominant shrub, often associated with Berberis lyceum, and on some east-facing slopes at higher altitudes there are communities dominated by Rosa webbiana and Ribes orientale. Other herbaceous plants growing on the sparse grassland, especially in gullies and ravines, are Salix denticulata, Mertensia tibetica, Potentilla desertorum, Juniperus polycarpus, alpine bistort, Berberis pachyacantha and Spiraea lycioides. Larger mammals found in this region include the Marco Polo sheep (Ovis ammon polii), the markhor (Capra falconeri), the ibex (Capra ibex) and the urial (Ovis orientalis vignei). The snow leopard (Panthera uncia) preys on these, and also on the pikas, hares and gamebirds found here. Other predators include the mountain weasel (Mustela altaica), the