Ground Vegetation Composition Research Articles

Effects of nitrogen fertilization on the ground vegetation cover and soil chemical properties in Scots pine and Norway spruce stands

The aim of this study was to investigate the short-term effects of nitrogen (N) fertilization intensity on the ground vegetation cover and soil chemical properties in two Scots pine (Pinus sylvestris L.) and two Norway spruce (Picea abies (L.) Karst.) dominated stands on upland forest sites in Eastern Finland. The fertilizer was applied using a helicopter in the spruce stands and a forwarder in the pine stands. The distribution and the amount of fertilizer was measured with funnel traps. Cover of each species of ground vegetation was estimated before fertilization and 3–4 years after it in pine and 2–3 years after it in spruce stands. Further, the cover observations were aggregated by plant types. Based on measurements, we analyzed the effects of the funnel-trap-observed amount of N fertilizer on the cover and plant type composition of ground vegetation and soil N and C concentration. In addition, we analyzed the impacts of competition caused by trees on the ground vegetation cover based on competition indices. N fertilization increased the cover of herbaceous plants and decreased the cover of mosses and dwarf shrubs, and the total cover of ground vegetation. Further, it increased the N concentration of the mor humus layer. The magnitude of the changes increased with the intensity of the N fertilization. The competition caused by trees did not affect the cover of ground vegetation.

Structure of the Ground Vegetation and Natural Regeneration of Tree Species in a 12–15-Year-Old Bilberry Pine Forest–Clear-Cut Ecotone Complex in the Middle Taiga Subzone

Abstract—Logging in mature stands, where part of the forest is harvested in one or several cuts and part is retained (clear-cutting and alternate strip cutting) results in the formation of an ecotone complex: forest (F), transition from forest to clear-cut under the canopy (forest edge – FE), transition from forest to clear-cut outside of the canopy (clear-cut edge – CE), and the clear-cut itself (C). Strips 8 m wide on each side of the mature forest/clear-cut site border form the transitional zone. We studied the ground vegetation composition and structure, and the natural regeneration of woody species (Pinus sylvestris L., Picea abies (L.) H. Karst., Betula sp., Populus tremula L., Sorbus aucuparia L., Juniperus communis L.) in the bilberry pine forest – clear-cut ecotone complex 12–15 years after the stand removal. The studies demonstrate that each of the four zones of the ecotone complex formed after logging of the mature forest has its own structural features of ground vegetation and undergrowth (including tree regeneration). The typical forest (F) habitat is characterized by the minimum number of young regeneration of Pinus sylvestris, Picea abies, Betula sp., Populus tremula, and Sorbus aucuparia and, on the contrary, by the highest abundance of lingonberry V. vitis-idaea L. and bilberry Vaccinium myrtillus L., and the maximum height of bilberry plants and their yield. The amount of tree regeneration in the FE is almost the same as in the F zone. The projective cover, maximum shoot height and yield of bilberry, and maximum shoot height of lingonberry in the FE zone are reliably lower than in the F zone. The transitional zone on the clear-cut side (CE) and the clear-cut itself (C) are distinguished from the forest sections of the ecotone complex (F and FE zones) by a greater number of deciduous and pine regeneration and the low abundance of dwarf shrubs. The clear-cut itself (C) differs from the CE by the higher abundance of grasses and forbs and an established tree regeneration layer composed of pine, birch, and aspen.

Long-term responses of ground beetles (Coleoptera: Carabidae) to clear-cutting and wildfire in lodgepole pine stands of western Alberta, Canada

Abstract We studied responses of carabid beetles (Coleoptera: Carabidae) to clear-cutting and wildfire in lodgepole pine forests in the foothills of Alberta, Canada during 2013–2014 and compared the results with those from a similar study conducted in the same area during 1989–1990. Assemblages from stands regenerating 12–53 years after harvest gradually recovered towards their presumed preharvest condition represented by old pyrogenic stands. Assemblage structure in postharvest stands of similar age had also largely converged with that in stands that had burned in 1957 and 1997. Composition of ground vegetation, mineral soil cover, and basal area of trees and shrubs were significantly correlated with carabid assemblage structure, suggesting that plant successional gradients and patterns in carabid assemblages are driven by similar factors. We found that no carabid species was strictly associated with old pyrogenic stands, although assemblages in pyrogenic stands were distinctive. We predict that composition of carabid assemblages in harvested stands will recover and roughly match the variable structure of assemblages remaining in old, never-cut pyrogenic stands, given sufficient time (≥ 50 years). Nonetheless, the carabid fauna of the eastern slopes of Alberta’s Rocky Mountains appears to be changing in response to factors other than forestry. Warming climate is an explanation consistent with the changes observed.

Assessing soil carbon dioxide and methane fluxes from a Scots pine raised bog-edge-woodland

Scots pine bog edge woodland is a type of habitat typical on raised bogs where trees cohabitate with bog vegetation to form a low-density stand. Even though nowadays this habitat does not cover large areas, in a future scenario it is possible that this environment will expand, either naturally (drier climate) or anthropogenically, as the result of the application of new restoration strategies that could increase net landscape carbon benefits from both peatland and woodland environments. This study is the first reported investigation in Scotland exploring carbon flux dynamics from sparse woodlands on raised bogs. We examined how Scots pine trees directly or indirectly affected soil temperature and moisture, ground vegetation, and consequently carbon dioxide (CO2) and methane (CH4) soil fluxes. Soil CO2 and CH4 were measured at different distance from the tree and thereafter assessed for both spatial and temporal variability. Our results showed that these low-density trees were able to modify the ground vegetation composition, had no effect on soil temperature, but did affect the soil moisture, with soils close to tree roots significantly drier (0.25 ± 0.01 m3 m-3) than those on open bog (0.39 ± 0.02 m3 m-3). Soil CO2 fluxes were significantly higher in the vicinity of trees (34.13 ± 3.97 μg CO2 m−2 s−1) compared to the open bog (24.34 ± 2.86 μg CO2 m−2 s−1). On the opposite, CH4 effluxes were significantly larger in the open bog (0.07 ± 0.01 μg CH4 m−2 s−1) than close to the tree (0.01 ± 0.00 μg CH4 m−2 s−1). This suggests that Scots pine trees on bog edge woodland may affect soil C fluxes in their proximity primarily due to the contribution of root respiration, but also as a result of their effects on soil moisture, enhancing soil CO2 emissions, while reducing the CH4 fluxes. There is, however, still uncertainty about the complete greenhouse gas assessment, and further research would be needed in order to include the quantification of soil nitrous oxide (N2O) dynamics together with the analysis of complete gas exchanges at the tree-atmosphere level.

Effects of overstory tree density, site preparation, and ground vegetation on natural Scots pine seedling emergence and survival in northern boreal pine forests

Natural regeneration is a commonly used forest regeneration method in northern Finland. It is not known, however, what would be the optimal overstory density and ground vegetation composition for seedling emergence and survival, and if site preparation is needed to accompany overstory density manipulation. We studied the effects of overstory density (unthinned control and thinning to 50, 150, and 250 trees·ha−1) and ground vegetation removal (mechanical site preparation with disc trenching) on the number of naturally germinated pine seedlings and survival of individual seedlings over a period of 8 to 11 years. Bare mineral soil was a superior seedbed compared to intact vegetation cover, even though the mortality rate was high on mineral soil. Greater cover of lingonberry, crowberry, and slash had a negative effect on seedling number. Seedling mortality was initially high (60% died during the first 2 years) but decreased throughout the first 5 years. The survival rate of seedlings located in the mineral soil of the upper part of the disc trencher track was twice as high as that of seedlings located in the lower part of the track. High coverage of hair mosses (Polytrichum spp.) was associated with poorer seedling survival. An overstory density of 50–150 trees·ha−1 with site preparation seems to be an efficient treatment to promote regeneration under these circumstances.

Legacy effects of sika deer overpopulation on ground vegetation and soil physical properties

Long-lasting overpopulation of deer can prevent or retard the recovery of ground vegetation of forests even after overpopulation would have abated. This persistent impact, or legacy effect of deer, would be explained by hypothetical mechanisms such as limitation of seed sources, dominance of competitors that are unpalatable to deer, and negative feedback from soil conditions degraded by direct and indirect effects of deer. So far, however, little evidence is available for existence of such legacy effects. To detect the legacy effects caused by sika deer (Cervus nippon) and reveal their possible mechanisms, we studied ground vegetation and soil condition of Japanese natural broad-leaved forests and cedar plantations, which have records of vegetation surveys of the past 11 years. Foliar cover and species composition of ground vegetation were analyzed together with the deer density index (DDI), which represents mean deer density of the last 9 years before the survey. The relationship between vegetation cover and deer density had significantly changed between the survey years, as was proved by a regression analysis. The cover of ground vegetation did not increase during the 11 surveyed years even at most study sites whose DDI value had decreased, thereby indicating the existence of legacy effects. This delay of recovery was not attributable to the dominance of unpalatable plants, which had slightly decreased during the 11 surveyed years. Palatable plants did not increase in most study sites where DDI decreased, suggesting seed source limitation. Negative indirect effects of DDI on soil physical property in the present, such as increased bulk density and decreased coarse porosity, were detected through structural equation modeling (SEM) analysis. In the case of broad-leaved forests, the SEM model that included the 2005 DDI values showed better performance than that using present DDI values, indicating a strong legacy of past deer impact. These facts suggest the existence of legacy effects, which possibly have been caused by seed source limitation and degraded soil conditions. Moreover, above statistical analyses showed that canopy closure, which can be caused by delayed management practices (e.g., gap creation and thinning), further limited recovery of vegetation. Ground vegetation of broad-leaved forests were suggested to show lower resilience than those of cedar plantations, requiring conservation activities such as canopy gap creation.

Wildlife forage cover and composition on pipeline corridors in Alberta: Implications for wildlife conservation

The construction of pipeline rights-of-way (ROWs, hereafter ‘pipeline’) involves mechanical site clearing, which impacts soil and ground cover vegetation and has implications for forage availability and predation risk for threatened wildlife, including woodland caribou (Rangifer tarandus) and grizzly bear (Ursus arctos). However, there has been no quantitative evaluation of vegetation communities on open pipelines as compared to the adjacent intact forest. We compared the cover of ground vegetation by vegetation type, and the cover and composition for plant taxa known for their importance as woodland caribou and grizzly bear forage, between plots located on pipeline corridors, near the edge of the pipeline corridor, and in the adjacent undisturbed forest across six different boreal forest ecosite types in west-central and north-western Alberta, Canada. Pipeline corridors were characterized by higher total ground vegetation cover, and cover of low shrubs, lichens, bryophyte and of targeted forage species of low shrubs, bryophytes, and lichens. In contrast, pipelines had higher graminoid cover and cover of target forage species of tall shrubs and graminoids, as compared to adjacent forest. Despite the substantive differences in cover and composition of ground vegetation among the ecosite types, differences between pipelines and the adjacent forest were quite consistent, with a few exceptions. For instance, forb cover was higher in the adjacent forest compared with pipelines in shrubby ecosite types, but was similar across plot locations in other ecosites. Species composition also varied among ecosites and differed between the adjacent forest and on pipelines; with pipelines dominated by graminoids, particularly Carex species. Our results demonstrate that pipelines influence ground vegetation communities, and cover and composition of wildlife forage species, across the boreal forest landscapes of Alberta; we suggest this results in pipelines being a potential ecological sink for wildlife populations, including threatened caribou. To ensure pipelines can recover, restoration strategies that promote natural recovery or purposeful re-planting may be required to accelerate forest re-establishment and put inactive pipeline corridors within caribou ranges on a recovery trajectory. Our results suggest that ecosites can be used to prioritize pipelines where restoration or management actions may be the most beneficial.

Long-term ecological consequences of forest fires in the continuous permafrost zone of Siberia

Wildfires are an important factor in controlling forest ecosystem dynamics across the circumpolar boreal zone. An improved understanding of their direct and indirect, short- to long-term impacts on vegetation cover and permafrost–vegetation coupling is particularly important to predict changes in carbon, nutrient and water cycles under projected climate warming. Here, we apply dendrochronological techniques on a multi-parameter dataset to reconstruct the effect of wildfires on tree growth and seasonal permafrost thaw depth in Central Siberia. Based on annually-resolved and absolutely dated information from 19 Gmelin larch (Larix gmelinii (Rupr.) Rupr.) trees and active soil layer thickness measurements, we find substantial stand-level die-off, as well as the removal of ground vegetation and the organic layer following a major wildfire in 1896. Reduced stem growth coincides with increased δ13C in the cellulose of the surviving trees during the first decade after the wildfire, when stomatal conductance was reduced. The next six to seven decades are characterized by increased permafrost active soil layer thickness. During this period of post-wildfire ecosystem recovery, enhanced tree growth together with positive δ13C and negative δ18O trends are indicative of higher rates of photosynthesis and improved water supply. Afterwards, a thinner active soil layer leads to reduced growth because tree physiological processes become limited by summer temperature and water availability. Revealing long-term effects of forest fires on active soil layer thickness, ground vegetation composition and tree growth, this study demonstrates the importance of complex vegetation–permafrost interactions that modify the trajectory of post-fire forest recovery across much of the circumpolar boreal zone. To further quantify the influence of boreal wildfires on large-scale carbon cycle dynamics, future work should consider a wide range of tree species from different habitats in the high-northern latitudes.

Wildfire effects on BVOC emissions from boreal forest floor on permafrost soil in Siberia

One of the effects of climate change on boreal forest will be more frequent forest wildfires and permafrost thawing. These will increase the availability of soil organic matter (SOM) for microorganisms, change the ground vegetation composition and ultimately affect the emissions of biogenic volatile organic compounds (BVOCs), which impact atmospheric chemistry and climate. BVOC emissions from boreal forest floor have been little characterized in southern boreal region, and even less so in permafrost soil, which underlies most of the northern boreal region. Here, we report the long-term effects of wildfire on forest floor BVOC emission rates along a wildfire chronosequence in a Larix gmelinii forest in central Siberia. We determined forest floor BVOC emissions from forests exposed to wildfire 1, 23 and > 100 years ago. We studied how forest wildfires and the subsequent succession of ground vegetation, as well as changes in the availability of SOM along with the deepened and recovered active layer, influence BVOC emission rates. The forest floor acted as source of a large number of BVOCs in all forest age classes. Monoterpenes were the most abundant BVOC group in all age classes. The total BVOC emission rates measured from the 23- and >100-year-old areas were ca. 2.6 times higher than the emissions from the 1-year-old area. Lower emissions were related to a decrease in plant coverage and microbial decomposition of SOM after wildfire. Our results showed that forest wildfires play an important indirect role in regulating the amount and composition of BVOC emissions from post-fire originated boreal forest floor. This could have a substantial effect on BVOC emissions if the frequency of forest wildfires increases in the future as a result of climate warming.

No Detectable Broad-Scale Effect of Livestock Grazing on Soil Blue-Carbon Stock in Salt Marshes

Grassland capturing and storage (CCS) is thought to benefit from regulation of grazing. The impact is likely to depend on livestock density. Yet, few studies have tested this principle or evaluated the consistency of grazer-carbon relationships across multiple sites. We sampled four intertidal zones across 22 salt marshes along a 650 km stretch of coast in the UK to examine the impact of livestock density on globally important saltmarsh blue carbon stocks. Although there were marked impacts of grazing pressure on above ground vegetation composition, structure and biomass, there was no detectable relationship between grazing intensity and soil organic carbon, irrespective of tidal zone in the marsh or soil depth-layer analyzed. A substantial spatial variation in soil was instead explained by contextual environmental variables. There was evidence that compensatory responses by vegetation, such as increased root growth, countered loss from grazing impacts. Our work suggests that grazing effects on stocks are minimal on broader scales in comparison with the influence of environmental context. The benefits of grazing management to stores are likely to be highly context dependent.

Assessing the Effects of Climate Change and Air Pollution on Soil Properties and Plant Diversity in Northeastern U.S. Hardwood Forests: Model Setup and Evaluation

The integrated forest ecosystem model ForSAFE-Veg was used to simulate soil processes and understory vegetation composition at three—sugar maple, beech, yellow birch—hardwood forest sites in the Northeastern United States (one at Hubbard Brook, NH, and two at Bear Brook, ME). Input data were pooled from a variety of sources and proved coherent and consistent. While the biogeochemical component ForSAFE was used with limited calibration, the ground vegetation composition module Veg was calibrated to field relevés. Evaluating different simulated ecosystem indicators (soil solution chemistry, tree biomass, ground vegetation composition) showed that the model performed comparably well regardless of the site’s soil condition, climate, and amounts of nitrogen (N) and sulfur (S) deposition, with the exception of failing to capture tree biomass decline at Hubbard Brook. The model performed better when compared with annual observation than monthly data. The results support the assumption that the biogeochemical model ForSAFE can be used with limited calibration and provide reasonable confidence, while the vegetation community composition module Veg requires calibration if the individual plant species are of interest. The study welcomes recent advances in empirically explaining the responses of hardwood forests to nutrient imbalances and points to the need for more research.

Ground vegetation composition and diversity in drained Norway spruce (Picea abies (L.) Karst.) stands 50 years after whole-tree harvesting management: case study in Latvia

Abstract The long-term (50 years) effect of whole-tree harvesting (stump harvesting) on ground vegetation in experimental drained Norway spruce (Picea abies (L.) Karst.) stands was studied. We used a chronosequence approach to assess the long-term impact of whole-tree harvesting (WTH) on stands’ ground vegetation. WTH stands were compared with four control stands with different age and with the same forest type: young stand (15 years), middle-aged stand (45 years), mature stand (110 years) and over-mature stand (140 years). Species richness was similar between the WTH stand and middle-aged stand (61 and 60 species, respectively). Shannon-Wiener diversity indices in the WTH and middle-aged stand (3.40 and 3.19, respectively) indicated that the stands were similar to each other. A community similarity analysis showed that the composition of vegetation was similar between the WTH and middle-aged stand, although some species like Lycopodium clavatum and Diphasiastrum complanatum occurred only in the WTH stand. The study showed that a period of 50 years is sufficient for ground vegetation of a typical drained spruce forest to recover after WTH management.

Horse Welfare and Natural Values on Semi-Natural and Extensive Pastures in Finland: Synergies and Trade-Offs

In several regions in Europe, the horse is becoming a common grazer on semi-natural and cultivated grasslands, though the pasturing benefits for animals and biodiversity alike are not universally appreciated. The composition of ground vegetation on pastures determines the value of both the forage for grazing animals as well as the biodiversity values for species associated with the pastoral ecosystems. We studied three pastures, each representing one of the management types in southern Finland (latitudes 60–61): semi-natural, permanent and cultivated grassland. All have been grazed exclusively by horses for several decades. We aimed to evaluate feeding values and horses’ welfare, on the one hand, and impacts of horses on biodiversity in boreal conditions, on the other. Though there were differences among the pastures, the nutritional value of the vegetation in all three pastures met the energy and protein needs of most horse categories through the whole grazing season. Some mineral concentrations were low compared to the requirements, and supplementation of Cu, Zn and Na is needed to balance the mineral intake. Only minor injuries or health problems were observed. All metrics of biological values, as well as number of species eaten by horses, were particularly high in a semi-natural pasture compared to other pasture types. The highest ratio of species cover preferred by horses to the total cover was found in the permanent pasture, while at the regularly re-seeded pasture, there was a particularly high cover of species, indicating low biodiversity values on grassland. There was, therefore, a trade-off between the quantity of forage and biological values in pastures, but not in quality. The results provide clear indication both for the suitability of the studied pasture types to horses and for grazing of horses for biodiversity management. In each pasture type, specific management is needed to simultaneously achieve objectives of adequate pasturing and biodiversity. The short duration (only one grazing season) must be considered when applying the results.

Composition of ground vegetation in Seblat Bukit forest bordering with Seblat Ulu Village, Kerinci Seblat National Park, Sumatra

Noviady I, Hidayat IW, Nurlaeni Y. 2017. Composition of ground vegetation in Seblat Bukit forest bordering with Seblat Ulu Village, Kerinci Seblat National Park, Sumatra. Pros Sem Nas Masy Biodiv Indon 3: 461-465. Seblat Bukit forest, which is a part of Seblat Mountain, belongs to the Kerinci Seblat National Park. Administratively, Bukit Seblat forest is directly adjacent to Seblat Ulu Village, Pinang Belapis Sub-district, Lebong District, Bengkulu Province. The area is dominated by natural forest whose the plant diversity is still high. It is recorded as many as 48 families of plants that can be found in the area. However, because it is directly adjacent to the settlements, it is inevitable that the diversity of plants in Bukit Seblat forest is threatened. Some locations are beginning to appear open related to the population activities, whether for coffee field, rice field, or other activities. The purpose of this research was to determine the diversity of species of tree seedling and their population that compose the ground vegetation in Bukit Seblat forest area. Data collection method was conducted by using plot 2 (5x1) m2. Plot placement was randomly dispersed in open forest and the area that was still covered by natural forest. From the research results, it was known that the plants in open area was as many as 48 species, more than in a closed area of 43 species. Plants in the open area were dominated by Calophyllum inophyllum L. with INP of 15.51% and for plants in closed areas were dominated by Argostemma involucratum Hemsl. with INP of 22.56%.

Topographically-controlled site conditions drive vegetation pattern on inland dunes in Poland

The inland dunes of Central Europe are commonly overplanted by Scots pine (Pinus sylvestris) monocultures in which the primary occurrence of the natural vegetation pattern is obliterated. We hypothesize that on naturally revegetated inland dunes the pattern is clear and driven by topographically-controlled site conditions. To test this hypothesis, we addressed the following research questions: (1) Does topography drive vegetation patterns on inland dunes and if so, what are main differences between vegetation in varying relief positions? (2) To what extent does topography involve the variability of microclimates and of soil properties, and how does the topographically-induced differentiation of these site conditions control vegetation patterns? We conducted interdisciplinary studies (applying floristic, pedological and microclimatic research techniques) on a naturally revegetated inland dune area situated on a military artillery training ground near Toruń, northern Poland. We investigated vegetation patterns with reference to three topographical position variants (north-facing slopes, south-facing slopes, and intra-dune depressions). We found distinct differences in vegetation characteristics covering the aforementioned topographical positions. This primarily concerned species composition of ground vegetation: Calluna vulgaris was dominant species on north-facing slopes, Corynephorus canescens on south-facing slopes, while Calamagrostis epigejos in intra-dune depressions. In comparison to dune slopes, the depressions were characterized by much higher biodiversity of vascular plant species. This followed the most favorable soil conditions for the existence of plants (higher moisture and nutrient pools) occurring in low topographical positions. However, tree succession was most advanced not in depressions, where the competitive impact of tall grasses on seedlings was recognized, but on north-facing slopes. Based on our results, we formulated some suggestions, which could be useful for both practical foresters to increase biodiversity of ecosystems and for practices that work on the fixation of dunes by restoring vegetation.

Habitat Selection by Northern Bobwhite Broods in Pine Savanna Ecosystems

Habitat for northern bobwhite (Colinus virginianus) broods is a critical component of bobwhite management. Research within pine (Pinus spp.) savannas has provided contradictory results regarding the value of macro-habitats with studies demonstrating selection for annually-disked fallow fields and others showing avoidance of fields and selection for burned pine savannas. Field establishment (up to 30% of a property) is a published management recommendation for bobwhites in pine savannas but there are significant annual costs with fallow-field management; information on factors that influence habitat selection by broods can improve management recommendations and facilitate weighing costs/benefits. We examined 2nd and 3rd order habitat selection by 466 broods on 3 sites during 1999–2009. All sites had similar macro-habitats (e.g., pine savanna, fallow fields, hardwood drains) but differed in soil characteristics and species composition of ground vegetation. Annually-disked fields were preferred by broods in most years on sites with predominantly grass and hardwood scrub ground vegetation. Rainfall mediated use of hardwood drains and burned upland pine savannas; hardwood drains were used more during droughts whereas burned pine savannas were used more with increased rainfall. Burned upland pine savanna was preferred on higher fertility sites in 9 of 10 years at the 3rd order level, fields were avoided or used according to availability in 8 of 10 years, and drains were avoided. Managers should consider how soil, weather, and vegetation community in pine savannas influences habitat use by bobwhite broods when identifying the value of different macro-habitats. Field establishment may or may not provide brood habitat depending on site.

Changes in the silver fir forest vegetation 50 years after cessation of active management

Knowledge of the vegetation and the monitoring of its changes in preserved areas is an essential part of effective conservation policy and management. The aim of this study was to assess the effectiveness of traditional methods of conservation of silver fir forests. The study analyses the changes in the structure and species composition of a temperate forest excluded from the commercial silvicultural management for 50 years, and since then protected as a nature reserve. The study is based on a comparative analysis of phytosociological reléves made on permanent plots in 1961, 1982, 1994 and 2011. PCA and ecological indicator values were analyzed, as well as characteristic species based on an indicator value (IndVal) index. Results revealed significant and dynamic changes in the forest structure and composition. The mixed coniferous-broadleaved forest with <em>Abies alba</em> and diverse ground flora, considered in the 1960s as valuable and worthy of conservation, was found to have been anthropogenically transformed and unstable. Significant reduction in the human impact was followed by spontaneous regeneration of oak–hornbeam forest. However, the directional process of changes in vegetation was modified by such silvicultural treatments as selective cutting of trees and gap creation, all intended for silver fir maintenance. The results show that <em>Carpinus betulus</em> effectively outcompeted <em>Pinus sylvestris</em>, <em>Picea abies</em>, <em>Quercus robur</em> and <em>A. alba</em>. Changes in the forest overstory and understory caused temporal changes in the habitat conditions reflected in changes in the ground vegetation composition. The proportion of light-demanding and oligotrophic species significantly decreased, while the contribution of species with a wide ecological amplitude, i.e. more shade-tolerant and nutrient-demanding – increased. The share of <em>A. alba</em> was reduced. Species defined in this study as most valuable, should be actively protected, or selection of conservation targets should be re-evaluated.

Land use legacies and site variables control the understorey plant communities in Mediterranean broadleaved forests

This study aimed to assess the influence of the past land uses on modern forest ground vegetation communities by combining historical records with field sampling. The history of forest uses was inferred from historical and census records, and site variables and ground vegetation composition were collected and measured based on 42 plots within five forests situated on the French-Spanish border. Both site and land use variables explained the observed pattern of ground vegetation composition. The most important part of this variation was explained by the site variables that bring together environmental and habitat variables. The chief determinants of forest use were the historical forestry treatment and the historical dominant livestock. The species assemblage of forests historically grazed by cattle and treated as coppice selective system or without forestry practices for more than a century reflected high level of disturbances. On the contrary, the species assemblage of the forests historically grazed by sheep and that experienced coppice selective system or both coppice-with-standards and timber forestry treatment reflected a lower disturbance context. Finally, the forest historically grazed by both cattle and sheep and treated as coppice-with-standard revealed an intermediate level of disturbances.

Nutrient limitation and site-related growth potential of Norway spruce (Picea abies [L.] Karst) in the Bavarian Alps

The hypothesis that soil chemistry is a main constraint for the vigour of Norway spruce trees on calcareous soils is scrutinised based on data from 60 existing and new intensive study sites in the Bavarian Alps, where comprehensive information on soils, climate, foliar nutrient concentration, ground vegetation, and tree growth is available. We characterised ecological gradients of the response variables site index (SI), foliar nutrient level and needle weight by constrained ordination, identified nutrient limitations based on regression trees and modelled SI based on vegetation-based mean Ellenberg indicator values. Our study confirms the assumption that soil development and concurrent acidification are key determinants for the vitality and growth of spruce in the Bavarian Alps, which surpass the importance of climate on nutrition and growth. Pools and availability of P and N are limiting nutrition and growth of spruce in this region. We hypothesize that N-limitation persists despite considerable deposition inputs because N tends to be locked up in organic horizons with low biological activity. K and trace elements, especially Fe, can also be deficient in some cases but do not appear as major limiting factors. High foliar Mn concentrations are a reliable indicator of mature soils and favourable site conditions in the Bavarian Alps, but Mn itself is usually not limiting. P must be regarded as the most critical macronutrient in the Bavarian Alps, particularly in the face of biomass harvesting. Consequently, at sites with shallow soils forest, management should focus on sustaining or restoring humus stocks. SI of spruce can be predicted from composition of ground vegetation and Ellenberg indicator values with remarkable precision (R 2 = 0.75).

Dépôts atmosphériques azotés et leurs effets en forêt: un bilan des sites d'observation à long terme

Nitrogen deposition and its effects in forests: results from long-term observation sites? Emissions of nitrogenous pollutants reached a peak in the mid-1980s and have decreased since then, but they remain at a high level. Long-term observation sites were established between 1984 and 1995 within three networks in Switzerland (IAP, LWF and NITREX), following growing concern that the vitality of forests might be affected by air pollution. Here we assess the nitrogen status of selected sites and its changes over the last 15 to 25 years. Nitrogen deposition at the sites was either obtained from models (IAP) or from throughfall measurements (LWF and NITREX). Indicators of the nitrogen status of a site included nitrate leaching from the rooting zone (43 sites), tree foliar concentrations of nitrogen and other nutrients (>100 sites), and the species composition of ground vegetation (59 sites). Nitrogen deposition has significantly decreased on eight out of twelve sites during the last 15 years. However, except in the Alps, deposition remains within or above the range of empirical critical loads, which correspond to the deposition levels above which the ecosystem might be negatively affected. Nitrate leaching can be locally high, depending on deposition rates, but also on other factors such as soil properties. Tree foliar concentrations in nitrogen and phosphorus have tended to decrease during the last 15 to 25 years. The comparison of vegetation surveys, first carried out in 1984, then repeated in 2003/2004, indicated an increase in nitrophilous species (IAP), but on a more recent and shorter period (1994/1998–2011), on a smaller number of sites (LWF), we found no significant changes.