Cathedral grove with very large dead firs at 1350 m, also young beech trees. The largest snag (centre left) is what remains of the largest tree found in Croatia’s montane virgin forests. Most of the largest trees in the reserve fell or sustained damage within the past 30 years

The decaying remnants of one of Europe’s most impressive old-growth groves in Nadžak Bilo is an example of the generational cycle shifts found in virgin forests. Elevation 1340 m

Beech–fir–spruce forest with some very large conifers at 1350 m. In the foreground is the largest living fir found in the reserve, while the large tree in the left background is the largest and tallest spruce. Both trees have had about half their trunk knocked off, but are still alive. Other trees are predominantly young beech which indicate a shift in species dominance as well as age structure in an area formerly occupied by giant conifers

Grove of large silver firs in the foreground, also a large dead beech to the far right. Elevation is 1320m

Despite its localized high density of very large conifer trees, most of Nadžak Bilo is covered by incredible groves of old beech trees. Elevation 1320 m

Beech grove with large mossy trees and lush fern undergrowth. Also a large spruce to the far left. Elevation is 1320m

Grove of large beech trees on a slope. Also, two beech snags in the foreground. For scale, the person in the photo is 193cm tall. Elevation is 1330m

Cathedral grove of large fir and beech trees on sheltered north-facing slope at 1330 m

Large firs and some beech on a terrace separating two sinkholes. Also some stones in the foreground. Elevation 1330 m

Large fir (foreground) and spruce (background) growing on the lush lower slope of a sinkhole at 1330 m

Largest living silver fir of Nadžak Bilo visible on the slope, behind beech trees. Elevation is ~1350m

A small sinkhole in the foreground at 1330 m, and in the background a larger sinkhole. Also a large uprooted conifer at the bottom of the first sinkhole

Two large spruces as well as beech. The spruce to the left is a decaying snag, while the spruce in the foreground is alive but has a dry and broken top. To the right is the bottom of a large sinkhole. Elevation is 1310m

Large spruce from the previous photo is visible in the background. It has a cbh of about 450 cm and a height of well over 40 m despite the broken top, so the former height was probably nearly 50 m. Also, large beech trees visible to the right with sycamore maple, far right. For scale, the person next to the tree is 193 cm tall. Elevation is 1320 m

Grove of beech on a slope dropping down to the bottom of a sinkhole. At the right bottom of the photo are some large conifer snags. Elevation is 1330m

A sinkhole bottom with cliffs on the opposing slope and many small sycamore maples. Elevation is 1300m

Large beech trees, also horizontally stacked cliffs in the center. Elevation is 1330m

Large uprooted fir. Elevation is 1340m

Beech forest with young firs. Elevation is 1330m

Large beech and fir individuals surrounded by regeneration of many young trees at 1360 m. This forest composition of very large individual trees surrounded by young growth is common in certain parts of the reserve and represents the shift in age structure

Large fir and beech trees below a ridgetop. Dead tree is fir. Elevation is 1350m

Fir dominated forest on the ridge with shorter trees and denser growth. Elevation is over 1360m

Beech dominated forest on the ridge with short and twisted trees. Elevation is 1370m

Despite a decline in the snag’s former dimensions, the cbh was still nearly 700 cm and trunk volume was estimated to be about 60 cubic metres based on the remains and photographs. The height was never measured but it was known to be one of the taller trees in the reserve. Judging by the fallen trunk as well as the heights of other smaller fir trees, it was likely well over 50 m tall when standing

The decaying remnants of one of Europe’s largest silver fir trees now provide nutrients to the saplings growing below. Elevation 1340 m

Near to the largest fir grows perhaps the most massive spruce of Croatia’s virgin forests, and also the tallest before it lost half of its trunk. The combination of the standing trunk height and the fallen trunk length is still about 59 m, however the highest point of the tree was in pieces, and it was estimated to go on for at least another 5 m, so perhaps it was about 64m tall once. Girth 560 cm, volume estimated at about 45 cubic meters before trunk break. Elevation 1340 m

Aside from dimensions, the Nadzak Bilo spruce is particularly interesting for its relatively low hanging branches and dense foliage

The Norway spruce from the previous photo, with relatively young beech forest around it

To the right is the tree from the previous photos, while to the left on the forest floor is the upper half of its trunk. Below on the slope is beech dominated forest. Elevation is 1340m

The broken trunk visible from the bottom of the slope. Also, beech and sycamore maple (left). Elevation 1330 m

Perhaps the largest living fir of Nadžak Bilo at 1350 m, also with trunk broken in half like the largest spruce. The cbh is 530 cm, and when unbroken it was probably about 35 cubic metres in volume

The largest living fir of the reserve at 1350 m, growing on a slope above the valley bottom

Large beech trees of Nadžak Bilo can reach heights of over 40m and a cbh of around 350cm. Elevation is 1340m

The largest sycamore maple measured so far at 1320 m, with a cbh of about 330 cm