By Order RD-223 of 26 .. 08. In 1994 the Ministry of Environment establishes a reserve Ulen area 3156.2 ha. It falls entirely within the territory of Pirin National Park. "
The aim of the natural object is to maintain without human intervention models of forest, subalpine and alpine ecosystems on siliceous rock base and habitats of rare, endangered and endemic plant species and zhivotineki.
The reserve is located from 1650 m to 2851 m altitude. In geomorphologic structure of the region are well defined glacial and periglatsialni forms generated during cooling pleystotsenskoto change.
Bedrock is represented by granite, granite, slate and crystal only Strazhishkiya circus is present ultrebazichni rocks from carbonate-silitsievzta Formation. In reserve are several stages vkslchocheni pond complex. These are Vasilashkite, Tipittskite, Strazhishkite, Polejanski, Disilishkite lakes and several singles from SLIC expire small mountain rivers.
The climate is mountainous. Vegetatsionnyat period of vegetation is - short of 100 to 130 days. Soils are brown forest, mountain-gorskitamnotsvetni and mountain-meadow.
The reserve has ancient forests of white fir, white pine, spruce, fir and dwarf pine. Single occurring century-old trees and pine-tree. The flora of the reserve has a rich stock. There have been 700 species of higher plants.
Forty-four of them are included in the Red Book of Bulgaria. Bright representatives planiskiyat peony, narcissiflora sasenka and golden columbine. Here can be found by other types of ice ages. These are black and extended empetrum sibaldiya.
Reserve plays a major role in species conservation as shipolista, elephants hobotniche, rock sedge, etc..
From the wildlife of the reserve typical representatives of mammals are bears, wolves and wild vvoza. Most mongobroyni are birds. Characteristic of the reserve are tits, woodpeckers, sokeritsata capercaillie Balkan partridge On sunny spots may be seen viper, and in some lakes and rivers meet balkanekata trout.