Legacy of pre-disturbance spatial pattern determines early structural diversity following severe disturbance in mountain spruce forests in Czech Republic

Background Severe canopy-removing disturbances are native to many temperate forests and radically alter stand structure, but biotic legacies (surviving elements or patterns) can lend continuity to ecosystem function after such events. Poorly understood is the degree to which the structural complexity of an old-growth forest carries over to the next stand. We asked how predisturbance spatial pattern acts as a legacy to influence post-disturbance stand structure, and how this legacy influences the structural diversity within the early-seral stand. Methods Two stem-mapped one-hectare forest plots in the Czech Republic experienced a severe bark beetle outbreak, thus providing before-and-after data on spatial patterns in live and dead trees, crown projections, down logs, and herb cover. Results Post-disturbance stands were dominated by an advanced regeneration layer present before the disturbance. Both major species, Norway spruce (Picea abies) and rowan (Sorbus aucuparia), were strongly self-aggregated and also clustered to former canopy trees, predisturbance snags, stumps and logs, suggesting positive overstory to understory neighbourhood effects. Thus, although the disturbance dramatically reduced the stand’s height profile with ~100% mortality of the canopy layer, the spatial structure of post-disturbance stands still closely reflected the pre-disturbance structure. The former upper tree layer influenced advanced regeneration through microsite and light limitation. Under formerly dense canopies, regeneration density was high but relatively homogeneous in height; while in former small gaps with greater herb cover, regeneration density was lower but with greater heterogeneity in heights

Impacts of soil conditions and light availability on natural regeneration of Norway spruce Picea abies (L.) H. Karst. in low-elevation mountain forests

& Key message Natural regeneration of P. abies (L.) H. Karst. may reach high densities in lower mountain elevations. The highest densities were found in sites with moderate light availability, with low pH, and not near the riverbank. However, age-height classes differed in the predicted magnitude of response, but were consistent in response directions. Mosses and understory species typical of coniferous forests were positively correlated with regeneration density. & Context Norway spruce Picea abies (L.) H. Karst. in Central Europe is at risk under climate change scenarios, particularly in mountain regions. Little is known about the impact of environmental factors on the natural regeneration of P. abies in lowelevation mountain forests. & Aims We aimed to assess impacts of distance from the riverbank, soil pH, and light availability on natural P. abies regeneration. We hypothesized that (1) natural P. abiesregeneration would depend on light availability and soil pH and (2) there are understory plant species which may indicate the microsites suitable for natural regeneration of P. abies. & Methods The study was conducted in the Stołowe Mountains National Park (SW Poland, 600–800 m a.s.l.). We established 160 study plots (25 m2 ) for natural regeneration, light availability, soil pH, and understory vegetation assessment

Effects of burrowing and burrow usage by badgers (Meles meles) and foxes (Vulpes vulpes) on soil properties and vegetation

In this study effects of burrowing by badgers and foxes on forest soil and vegetation were examined. Burrow digging resulted in increasing topsoil alkalinity and changing the availability of some nutrients. Soil disturbances supported higher diversity of herbaceous and woody plants, and favoured the occurrence of fugitive and nutrient demanding species. Badgers had stronger impact on soil and vegetation than foxes

Rapid spread of a fleshy-fruited species in abandoned subalpine meadows - formation of an unusual forest belt in the eastern Carpathians

In recent decades, most subalpine hay meadows and pastures have been abandoned, and trees have been recolonizing these sites where forest existed before agricultural activity. This study examined how woody vegetation, dominated by the deciduous fleshy-fruited tree Sorbus aucuparia (rowan), expanded on subalpine meadows in the Western Bieszczady Mountains (eastern Carpathians, Poland) after the cessation of agricultural use. The aims were to determine the abundance of rowan in the woody vegetation, to estimate the rate of rowan expansion in the studied area, and to characterize the variability of rowan stands and growth forms. Rowan dominated the current plant community of abandoned subalpine meadows, though this species is not considered a rapid colonizer of open areas and was not frequent in the uppermost forest belt before the colonization. The whole area was encroached by rowans in a very short period of time 60-70 years ago. Rowan tree density was similar throughout the elevational gradient but the growth form changed, becoming more shrub-like with increasing elevation. Rowan stands will likely be the main element of the subalpine belt in this region in the upcoming decades. At present, no tree species can be considered a rapid successor to rowan in the area

Changes of spruce stands in the lower mountain forest belt subjected to active protection in the Tatra National Park

One of the most important objective of the active nature protection in national parks situated in Polish mountains is the restoration of mixed stands replaced by Norway spruce monocultures. Seven spruce stands situated in the Tatra National Park were measured in 1983−1986 and in 2001. The density of all stands decreased whereas the basal area and volume increased. In some of them the changes were considerable. The contribution of Fagus sylvatica and Abies alba, two most important tree species in natural mountain forests, changed only slightly and even decreased in three stands. Intensity of elimination of trees was related to their thickness – thin trees were removed from stands more often. Due to this way of thinning the variation of tree thickness diminished in all spruce stands. The densities of Fagus sylvatica and Acer pseudoplatanus saplings increased in all stands as a result of former planting. However, they are still to low for effective restoration of mixed stands. It can be concluded that mainly sanitary cuttings have been used recently in all stands. This line of management is not deliberately focused on the restoration of mixed stands and the diversification of their structure. It results in aging of dense spruce stands and increases the risk of future large−area disturbances due to strong winds and insect outbreaks

Changes of a subalpine spruce forest in the Tatra National Park in 1973-2002

The paper presents nearly 30−year changes in the structure of a 160 ha subalpine spruce stand in the Tatra National Park that has been subjected to strict protection during last 50 years. In 1973 a regular network of 65 small 0.05 ha circular plots was established over the whole area. In 2002 diameter and height of trees were remeasured in 61 plots. Similar changes were recorded nearly in the whole forest area. The density of trees decreased and the stand volume increased considerably on most plots. At the same time the variability among plots in trees' number and volume decreased and in 2002 the stand became more homogenous in terms of both characteristics. The obtained results were compared to the suggestion of Korpeľ that subalpine spruce stands reach the equilibrium between decay and growth processes on the area of 70 ha. The investigated forest was far from such equilibrium in spite of its area being more than two times bigger than that suggested by Korpeľ