Shrub Layer Research Articles

Balkan Vegetation Database (BVD) – updated information and current status

The Balkan Vegetation Database (BVD; GIVD ID: EU-00-019) is a regional database, which was established in 2014. It comprises phytosociological relevés covering various vegetation types from nine countries of the Balkan Peninsula (Albania – 153 relevés, Bosnia and Herzegovina – 1715, Bulgaria – 12,282, Greece – 465, Croatia – 69, Kosovo – 493, Montenegro – 440, North Macedonia – 13 and Serbia – 2677). Currently, it contains 18,306 relevés (compared to 9.580 in 2016), and most of them (82.8%) are geo-referenced. The database includes both digitized relevés from the literature (65.6%) and unpublished data (34.5%). Plot size is available for 84.7% of all relevés. During the last four years some “header data information” was improved e.g. elevation (now available for 83.4% of all relevés), aspect (67.7%), slope (66%), total cover of vegetation (54.3%), cover of tree, shrub, herb, bryophyte and lichen layers (27.1%, 20.1%, 40.2%, 11.5% and 2.1%), respectively. Data access is either semi-restricted (65.6%) or restricted (34.4%). Most relevés (84.6%) are classified to syntaxa of different levels. The database has been used for numerous studies with various objectives from floristic, vegetation and habitat-related topics, to macroecological studies at the local, regional, national, continental and global levels. During the last four years, BVD data were requested from 111 different projects via the EVA and sPlot databases.

STONE-BIRCH FORESTS ON THE GOVENA PENINSULA AND OLYUTORSKY GULF COAST (KORYAKSKY DISTRICT, KAMCHATKA KRAI)

Stone-birch (Betula ermanii) forests were studied at the northern limit of their range in the north of the Koryaksky District. The species composition, community structure, and habitats of stone-birch groves are described. Their altitudinal position and geographical distribution are discussed. A classification of stone-birch communities on Olyutorsky Gulf coast was developed using the dominant-determinant approach. Within the study area, the community diversity of stone-birch forests was represented by 5 associationsforming 3 groups of associations: Betuleta pteridosa (fern-rich stone-birch forests), Betuleta calamagrostidosa (grass-rich stone-birch forests), and Betuleta fruticosa (shrub-rich stone-birch forests). All the syntaxa have been previously described from the Kamchatka Peninsula. The Koryak communities differed from their Kamchatka analogues in the floristic composition, lower species diversity, and high density of the shrub layer. The most important characteristics of shrub-rich stone-birch communities were the high abundance of Sorbus sambucifolia and Alnus fruticosa, while for fern-rich communities it was the predominance of Dryopteris expansa in the herb layer. The intrazonal stone-birch groves are considered to be the remnants of widespread birch forests of the Holocene climate optimum, which ended ca. 5 Ka B. P. They have survived on the southern maritime slopes of the Koryak Upland ridges and turned into fragmentary and floristically impoverished communities. The relic stone-birch groves of the Koryak Upland are regarded as rare and endangered communities in need of special protection.

Colonization by native species enhances the carbon storage capacity of exotic mangrove monocultures

BackgroundThe fast-growing introduced mangrove Sonneratia apetala is widely used for mangrove afforestation and reforestation in China. Some studies suggested that this exotic species outperforms native species in terms of carbon sequestration potential. This study tested the hypothesis that multi-species mangrove plantations might have higher carbon sequestration potential than S. apetala monocultures.ResultsOur field measurements at Hanjiang River Estuary (Guangdong province, China) showed that the carbon stock (46.0 ± 3.0 Mg/ha) in S. apetala plantations where the native Kandelia obovata formed an understory shrub layer was slightly higher than that in S. apetala monocultures (36.6 ± 1.3 Mg/ha). Moreover, the carbon stock in monospecific K. obovata stands (106.6 ± 1.4 Mg/ha) was much larger than that of S. apetala monocultures.ConclusionsOur results show that K. obovata monocultures may have a higher carbon accumulation rate than S. apetala monocultures. Planting K. obovata seedlings in existing S. apetala plantations may enhance the carbon sink associated with these plantations.

Natural forest colonisation and soil formation on ash dump in southern taiga

Abstract Ash dumps occupy significant areas around the world and make a negative influence on the environment. This effect is decreased by their natural colonisation determined by the bioclimatic conditions of the area. The purpose of the current study was to identify the structure of the forest communities and the initial stages of soil formation on the ash dump in southern taiga. This study was carried out on three sites in the forest phytocoenosis formed in the process of revegetation of the Verkhniy Tagil Power Station ash dump over 50 years, as well as on two background forest sites in the Middle Urals. Complex geobotanical and soil studies were carried out. The results of the study show that forest phytocoenoses with a predominance of hardwood species (Betula pendula Roth and Populus tremula L.) and a small admixture of coniferous species can form on the non-recultivated ash dump within 50 years in a boreal zone. In total, the studied mixed forest phytocoenoses are similar in composition to zonal secondary forests, but differ by having lower height and diameter of the stand, as well as herb–shrub layer coverage. Their species density and floristic richness are also lesser. The study proved that the process of soil formation is also proceeding according to the zonal type in the ash substrate under forest communities. The results of the study can be applied to justifying the forecasts of ecosystem restoration on the technogenic substrate, as well as for the species selecting for their recultivation in the studied area and similar to it.

Diversity and ecology of forest communities in Küre Mountains National Park of Turkey

This study aimed at analyzing the diversity and ecological characteristics of forest associations (121 releves classified under eight associations) in Kure Mountains National Park. Ordination analyses (DCA and CCA) and response curves were used to reveal ecological characteristics of vegetation using soil parameters (pH, electrical conductivity, sand, clay and dust content, soil moisture) and topographical variables (altitude, slope, potential direct incident radiation and heat load). Ecological conditions of communities were also tested using average Ellenberg indicator values (EIVs). Among forest associations, the highest species diversity was found in Phillyreo latifoliae-Pinetum brutiae and the lowest diversity in Hedero-Castanetum sativae, which had a dense Rhododendron ponticum shrub layer. However, Salicio-Platanetum orientale and Buxo sempervirens-Carpinetum betuli had the highest beta diversity since they harbored unique species composition. Conditional effects of altitude, slope, pH and electrical conductivity, soil dust and sand content, sandy-loam and loam soil types presented significant contributions in species composition. While Carpino-Quercetum petraeae was found on soil with high dust content having high pH and electrical conductivity values, Quercetum roburi-Aceretum campestri and Salicio-Platanetum orientale were related to soil with loam. Species responses to soil and topographical variables varied for most tree species. Light EIVs, which has a high positive correlation with potential direct incident radiation and heat load, related to Phillyreo latifoliae-Pinetum brutiae and Salicio-Platanetum orientale. Riverside forest communities differed from other communities in nutrient and humidity EIVs. However, EIVs did not show a good correlation with associated soil parameters such as soil moisture-humidity EIVs and soil pH-acidity EIVs.

The investigation of ground beetles shape (Coleoptera: Carabidae) and its relationship to the species structure of vegetation in a mixed forest (by the example of the Pustynsky sanctuary, Nizhny Novgorod Region)

This paper is devoted to the investigation of the relationship between the body shape of the imago of ground beetles and the structure of vegetation layers in the mixed boreal forest located in the State Natural Biological Sanctuary Pustynsky, Nizhny Novgorod Region. The materials were collected in the July 2019. 23 sampling sites were established. Vegetation was described at each site and ground beetles were sampled. Representatives of 8 carabid genera were found (Amara, Calathus, Carabus, Cymindis, Harpalus, Notiophilus, Pterostichus, Synuchus). Ground beetles shape analysis was carried out with methods of geometric morphometry. As a result of the analysis, a morphospace was formed. The analysis of shape variability was carried out, which showed that interspecific variability prevailed over intraspecific variability. The relationship between ground beetles shape and species structure of vegetation layers was carried out with a multivariate redundancy analysis. We did not find statistically significant influence of the structure of tree and shrub layers on ground beetles shape, but found the impact of the herb layer. A more heterogeneous herbaceous layer is preferred by species with a body shape characteristic of zoophages, and simplification of the structure of herbaceous vegetation leads to the prevailing of mixophytophages shape.

Understory vegetation dynamics of Chinese fir plantations and natural secondary forests in subtropical China

Understory vegetation is a vital component of forest ecosystems and contributes to terrestrial plant diversity, nutrient cycling and energy flows. Plantations and natural secondary forests are two dominant types that emerge following stand-replacing disturbances in managed landscapes. However, to date, the long-term dynamics of the cover, diversity, and composition of understory vegetation in plantations and secondary forests remain poorly understood. We sampled understory vegetation of Chinese fir plantations and natural secondary forests with their ages spanning 4 to 40 years and used primary forests as a reference in subtropical China. The cover and species diversity of the shrub layer were significantly higher in the natural secondary forests than in Chinese fir plantations in two younger age classes, but they converged in older stands. In the herb layer, Chinese fir plantations possessed a higher total and vascular species diversity across all age classes, but their covers did not differ significantly between the two forest types, except for a higher cover of vascular plants in the 8–12-year-old Chinese fir plantations. The bryophyte cover did not differ with forest type nor stand age, while bryophyte species diversity was significantly higher in Chinese fir plantations. The cover and species diversity of understory vegetation in the primary forests were similar to those in the 35–40-year-old natural secondary forests. Across all forest types and age classes, the cover and diversity were positively correlated within each plant group, and the shrub cover and diversity were negatively correlated with vascular diversity in the herb layer, but neither the cover nor the diversity of bryophytes was correlated with those of the shrub layer or herb layer. Species composition differed significantly with forest type and stand age. Natural secondary forests had more similar understory species composition to primary forests than Chinese fir plantations did. Our results suggest that forest management may increase the diversity of the herb layer, but at the expense of the abundance and diversity of the shrub layer. The shrub layer may not regenerate, or its regeneration will be slow due to exhausted seed and propagulum banks after multiple management rotations. Moreover, the high cover of the shade-intolerant and nutrient-demanding herbaceous plants in Chinese fir plantations may have adverse effects on ecosystem service functions.

Long-Term Changes of Softwood Floodplain Forests—Did the Disappearance of Wet Vegetation Accelerate the Invasion Process?

Objectives: We followed the long-term changes of softwood floodplain forests strongly altered by water regime changes and examine the behaviour of neophytes in this environment. Here we ask: (1) How did the composition of neophyte and native species change? (2) How did the presence of species that prefer wetter conditions change? (3) What traditionally distinguished type of softwood floodplain forests (a wetter one or a more mesophilous one) do neophytes prefer? (4) What environmental factors affect the native species richness and the occurrence and cover of neophytes? Materials and Methods: Historical and recent phytosociological relevés of the association Salicetum albae of the Slovak part of the inland delta of the Danube River were used (177 plots together). For each plot, the number and cover of neophytes and number of native species were measured, and the Shannon-Wiener diversity index, the stand structure (cover of tree, shrub and herb layer) and the mean of Ellenberg indicator values were calculated and compared among time periods. Temporal trends of the soil moisture characterized by indicator values calculated for each plot were determined using a Linear Model. The synoptic table of traditional vegetation types was done to show preferences of neophytes for particular softwood forest types. The effect of site conditions on native species richness and occurrence of neophytes was determined using the Generalized Linear Model. Results: The relative number and cover of neophyte species increased and the absolute number of native species decreased over time; the vegetation of the area has changed from variable hygrophilous and mesophilous to homogenised mesophilous; most non-native species prefer the mesophilous vegetation of the floodplain forests; the wetter parts of the floodplain more successfully resisted invasions. Conclusions: The vegetation of the researched area has considerably changed over time to become less diverse and less hygrophilous, and has more invasive species. To preserve floodplain forests, natural hydrological and connectivity patterns should be adequately protected.

Spatial distribution of plant diversity in shrub layer of Quercus variabilis plantation and its relationship with light environment

We analyzed the spatial heterogeneity of plant species diversity in shrub layers and its relationship with light environment in Quercus variabilis plantation and Q. variabilis-Platycladus orientali mixed forest, following the method of geostatistics. The results showed that plant species diversity indices (Shannon H, Simpson Ds, Margalef Ma) of shrub layers in Q. variabilis plantation were significantly lower than that in Q. variabilis-P. orientalis mixed forest. The variation ranges and spatial autocorrelation distances of plant species diversity index in Q. variabilis plantation were higher than that in Q. variabilis-P. orientalis mixed forest, with lower spatial homogeneity but stronger spatial dependence. The plant species diversity indices of H, Ds and Ma structural ratios of shrub layers in Q. variabilis pure forest were 44.2%-49.7%, with moderate spatial autocorrelation. The structure ratios of H, Ds and Ma in Q. variabilis-P. orientalis mixed forest were 1.5%-3.3%, with strong spatial autocorrelation. The spatial distribution of biodiversity showed obvious strip-like gradient trend in Q. variabilis plantation and patchy gradient change in Q. variabilis-P. orientalis mixed forest, suggesting that the spatial continuity of plant species of shrub layers was worse in Q. variabilis-P. orientalis mixed forest and that the spatial variation was stronger than that in Q. variabilis pure forest. Results of correlation analysis and stepwise regression analysis showed that the total light and plant canopy openness were the most significant factors affecting plant species diversity of shrub layers in both forest types. Light environment formed by plant canopy structure played a crucial part in maintaining plant diversity in shrub layer.

Diversity of Plants in Thickets of Invasive Sorbaria sorbifolia: Differences in the Effect on Aboveground Vegetation and Seed Bank

The diversity of aboveground vegetation of the herb–dwarf shrub layer and seedlings from the soil seed bank in the thickets of invasive shrub Sorbaria sorbifolia was evaluated in urbanized forests of the city of Yekaterinburg (the Middle Urals, Russia). Geobotanical releves and identification of seedlings from the soil seed bank were performed in different forest communities: thickets of invasive S. sorbifolia, thickets of native Rubus idaeus, and in forest communities without S. sorbifolia and R. idaeus. The effect observed in the presence of S. sorbifolia was as follows: the abundance of aboveground vegetation in the herb–dwarf shrub layer was lower by a factor of 10–20 or more; the taxonomic richness of the herb–dwarf shrub layer in the releve (α-diversity), by a factor of 6–8; and the total number of species recorded in the community group (γ-diversity), by a factor of 3. The disappearance of species under S. sorbifolia was selective. Relatively light-loving and relatively dry-loving species disappeared first, while more shade-loving and moisture-loving species were relatively resistant. The taxonomic richness and abundance of seedlings from the soil seed bank did not change depending on the abundance of S. sorbifolia. Approximately half of the identified seedling taxa were typical forest plants, while the others were only specific for the seed bank and did not occur in the vegetative state. It is concluded that the influence of S. sorbifolia on the vegetation of subordinate layers is due primarily to the direct competitive and habitat-transforming effect of the living S. sorbifolia phytomass.

Harnessing terrestrial laser scanning to predict understory biomass in temperate mixed forests

Forest understory vegetation plays an important role in providing food, nutrition and habitat for wildlife. The impact of wildlife foraging on forest understory biomass are often subtle processes that are difficult to capture using traditional field measurements. Field measurements are labor-intensive and impractical to cover and detect understory biomass changes at an extensive range with fine spatial resolution, thereby affecting the accuracy of habitat quality and food availability assessment for wildlife. Terrestrial Laser Scanning (TLS) is considered to have potential to improve the accuracy of understory biomass prediction, allowing for detailed monitoring of biomass changes under the influence of wildlife at fine scale. In this study, we first developed an efficient method to predict forest understory biomass by using variables from TLS with regression models, and second, we compared the prediction accuracy between TLS-based variables and field-measured variables. Third, the optimal models with TLS-based variables were applied to map and quantify the effect of herbivores density on understory biomass in temperate forests in northeastern China. Our results demonstrated that TLS-derived data were more accurate than field measurements in predicting understory biomass, that TLS-derived canopy cover yielded the highest herb layer biomass estimation accuracy (R2 = 0.72, RMSE = 12.73 g/m2), and that TLS-derived vegetation volume obtained the highest accuracy assessment for the shrub layer biomass prediction (R2 = 0.69, RMSE = 43.64 g/m2). There was a significant difference in the understory herb layer biomass in different deer-density plots, but no significant difference in shrub layer biomass. To quantify biomass changes in different plots, consistent monitoring method is needed, TLS data demonstrated the potential to capture and accurately quantify the biomass variation from forest understory. As tool for monitoring understory, TLS can be used as a supplementary to traditional understory monitoring methods to guide forest management policies and wildlife conservation strategies.

Does the shrub layer act as an intermediary? Effects on abundance of insects and abundances of particular insect orders caught flying in the canopies of deciduous forests in Central Germany

Scientists and society are increasingly becoming aware of loss of insect biodiversity and biomass. The level of biodiversity determines the efficiency of ecological communities to capture essential resources, produce biomass, decompose and recycle nutrients. Relationships between plant and insect diversity can be modified by changes in insect abundance. This study determined the associations between microclimate and diversity of forest plants on overall insect abundance and abundances of different insect orders in the canopy of temperate deciduous forests dominated by Fagus sylvatica L. (European beech; Fagaceae) in Central Germany. Following model selection, a linear mixed model was used to analyse the associations between abiotic factors (air temperature and relative humidity) as well as biotic factors (species richness and cover for the ground, shrub and tree layer) and insect abundance and abundances of insect orders. Within similar strength of evidence, best models were chosen as those with a single explanatory parameter. Significant associations were recorded between abundances of Lepidoptera and Neuroptera and relative air humidity, insect abundance and species richness in the shrub layer, and between abundances of Diptera and Psocoptera and percentage cover of shrubs. Trends in associations were detected between the abundance of Hemiptera and species richness recorded in the shrub layer, and between the abundance of Thysanoptera and the species richness in the ground layer. No significant associations with single explanatory parameters were recorded for the abundances of Coleoptera and Hymenoptera. Phytodiversity, especially that in the shrub layer, were more often associated with the abundances of insect orders than microclimatic factors. The potential importance of the association between shrub layer parameters and the abundance of insects might be based on the shrub layer combining the associations with the ground layer (bottom-up processes) and canopy layer (environmental conditions). In addition, associations between phytodiversity and abundance of insects seem to vary most for Coleoptera and Hymenoptera in which there are markedly different functional groups.

Altitudinal pattern of shrub biomass allocation in Southwest China.

Shrubs play an important role in the global carbon cycle and are particularly sensitive to climate change. However, the altitudinal pattern of biomass allocation in mountainous shrubs and its responses to climate change are still unclear. In this study, biomass accumulation and allocation of the shrub community and their relationships with climatic factors were investigated in 331 sampling sites along an extensive altitudinal gradient (311–4911 m) in Southwest China. The results showed that the above-ground biomass (AGB) and the total biomass (TB) of the shrub community decreased quadratically (R2 = 0.107) and linearly (R2 = 0.024) from 9.86 to 0.15 kg·m-2 and 15.61 to 0.26 kg·m-2 with increasing altitude, respectively. However, the below-ground biomass (BGB) and TB of the herb layer increased quadratically with increasing altitudes (R2 = 0.136 and 0.122, respectively. P<0.001). The root/shoot ratio (R/S) of the community and its component synusiae increased gradually with increasing altitudes (P<0.001). The standardized major axis (SMA) indicated an isometric relationship between AGB and BGB for the whole shrub community, but allometric relationships were found for the shrub and herb layer. Redundancy analysis and Pearson correlation analysis showed that the biomass and R/S were significantly correlated with mean annual temperature (MAT), mean annual precipitation (MAP) and reconnaissance drought index (RDI). These findings indicate that shrub biomass allocation is strongly affected by the altitude, MAT and MAP and support the isometric relationship of AGB and BGB partitioning at the community level on mountainous shrub biomes.

Evaluating structural and compositional canopy characteristics to predict the light‐demand signature of the forest understorey in mixed, semi‐natural temperate forests

AbstractQuestionsLight availability at the forest floor affects many forest ecosystem processes, and is often quantified indirectly through easy‐to‐measure stand characteristics. We investigated how three such characteristics, basal area, canopy cover and canopy closure, were related to each other in structurally complex mixed forests. We also asked how well they can predict the light‐demand signature of the forest understorey (estimated as the mean Ellenberg indicator value for light [“EIVLIGHT”] and the proportion of “forest specialists” [“%FS”] within the plots). Furthermore, we asked whether accounting for the shade‐casting ability of individual canopy species could improve predictions of EIVLIGHT and %FS.LocationA total of 192 study plots from nineteen temperate forest regions across Europe.MethodsIn each plot, we measured stand basal area (all stems &gt;7.5 cm diameter), canopy closure (with a densiometer) and visually estimated the percentage cover of all plant species in the herb (&lt;1 m), shrub (1–7 m) and tree layer (&gt;7 m). We used linear mixed‐effect models to assess the relationships between basal area, canopy cover and canopy closure. We performed model comparisons, based on R2 and the Akaike Information Criterion (AIC), to assess which stand characteristics can predict EIVLIGHT and %FS best, and to assess whether canopy shade‐casting ability can significantly improve model fit.ResultsCanopy closure and cover were weakly related to each other, but showed no relation with basal area. For both EIVLIGHT and %FS, canopy cover was the best predictor. Including the share of high‐shade‐casting species in both the basal‐area and cover models improved the model fit for EIVLIGHT, but not for %FS.ConclusionsThe typically expected relationships between basal area, canopy cover and canopy closure were weak or even absent in structurally complex mixed forests. In these forests, easy‐to‐measure structural canopy characteristics were poor predictors of the understorey light‐demand signature, but accounting for compositional characteristics could improve predictions.

Structure and dynamics of a mountain riparian forest at an upstream valley in central Japan

AbstractThis paper reports the data collected in censuses of trees, litter fall and vegetation in a mountain riparian forest, upstream of the Watarase river, Gunma Prefecture in central Japan. A 1‐ha permanent plot (100 m × 100 m) subdivided into horizontal 10 m × 10 m grid cells was established in the forest in 2005. Tree census with woody species ≥15 cm girth at breast height was conducted every year from 2005. Twenty‐five litter traps were set in the permanent plot. The samples of litter fall were collected monthly, except in winter, between 2005 and 2008. And we sorted into leaves, branches, reproductive organs and other plant material, at species level as much as possible. The percentage cover of vascular plants was recorded at each vertical stratification (tree layer, subtree layer, shrub layer and herb layer) in 2008 and 2014 at the plot. These data are valuable for elucidating long‐term forest dynamics at mountain upstream areas experiencing frequent ground disturbances.The complete data set for this abstract published in the Data Paper section of the journal is available in electronic format in MetaCat in JaLTER at http://db.cger.nies.go.jp/JaLTER/metacat/metacat/ERDP-2020-15.1/jalter-en.

Tree species composition and selection effects drive overstory and understory productivity in reforested oil sands mining sites

AbstractReforestation is a feasible option for the eventual restoration of biodiversity and ecosystem services on deforested oil‐sands mining sites. The associations between plant diversity and productivity spanning the different strata of restoration forests, in conjunction with specific factors that may impact these relationships, remain uncertain. We sampled 94 sites that encompassed conifer, mixed‐wood, and broadleaved overstory types as three exemplar substrates following the reforestation of oil‐sands mining sites in Alberta, Canada. We employed structural equation modeling to investigate the correlations between species diversity and aboveground biomass production spanning forest vegetation strata, while concurrently accounting for the effects of overstory composition, functional diversity/identity, soil fertility, and restoration age. We found that the relationships between species diversity and biomass were negative, or inconsequential across restoration forest strata. Overstory biomass was linked to the coniferous tree proportion and community‐weighted mean of leaf nitrogen, rather than the species and functional diversity of overstory trees. Further, overstory composition, diversity, and biomass were the key features involved in the diversity and biomass of understory strata. Our results demonstrated the importance of overstory tree species composition and selection effects toward driving overstory and understory productivity in restoration forests at post‐oil sands mining sites. Coniferous trees were observed to have lower leaf nutrient levels and negative impacts on the productivity and diversity of overstory and shrub layers. Therefore, it was recommended that a greater proportion of broadleaved trees should be incorporated to promote productivity and species diversity in restoration forests through the enhancement and utilization of available resources.

The Persisting Influence of Edge on Vegetation in Hemiboreal Alnus Glutinosa (L.) Gaertn. Swamp Forest Set-Asides Adjacent to Recently Disturbed Stands

To increase set-aside areas and protect biodiversity values in managed hemiboreal forest landscapes, small forest parcels called Woodland Key Habitats have been designated in Baltic and Nordic countries. The aim of this study was to investigate the persisting influence of the edge on vegetation dynamics for young, medium-old and old edges in Alnus glutinosa (L.) Gaertn. Woodland Key Habitats. All of these edges are adjacent to recently disturbed (clear-cut) stands. We surveyed edge influence on vegetation in bryophyte, herbaceous, shrub and tree layers in 90 plots in 30 set-aside forest stands in Southern Latvia. We tested the differences in the number of species and projective coverage in all vegetation layers, but plant functional types were examined—separately in the herbaceous layer. We found that edge influence in protected forest stands of A. glutinosa swamp forests reflects strong changes in vegetation and plant functional types in the herbaceous layer mostly up to 20 years after clear-cut disturbance in adjacent stands. The greatest differences were between young edges (≤20 years) and old edges (≥41 years), but there were very few significant differences between medium-old (21–40 years) and old edges which signifies more rapid changes in the early stages of edge influence and gradual stabilization of vegetation later on. We found that in edges adjacent to recently disturbed stands (up to 20 years), significantly less rare and indicator epiphytic lichen species occur, but this occurrence increases over time and edge influence is no longer present beyond 20 years after disturbance. Changes in vegetation and species occurrence found in our study indicated the need to plan the allocation of set-aside patches in production forest landscapes to ensure connectivity over longer period of time. Careful planning of clear-cuts in neighboring areas over time can significantly reduce the impact of edge effect on these set-asides.

LONG-TERM RELATIONSHIP BETWEEN OAK DECLINE AND SHRUB GROWTH DYNAMICS IN AN HUNGARIAN OAK FOREST, 1972-2017

Long-term structural dynamics of shrub layer of temperate oak forest communities were not extensively reported in published studies. The serious oak decline was first reported in 1979-80 and nowadays 63.0% of canopy oak trees died in a forest stand. The data were used to obtain (1) quantitative information on shrub layer growth, including height (H) and shoot diameter (DSH) condition and basal area (BA) values; (2) structural information on foliage cover rate of the shrub layer, mean cover of some shrub species; (3) comprehensive description from the ecological processes in the shrub layer in the last 45 years and our objective was (4) to analyze the possible effects of oak decline on the shrub growth dynamics. The following measurements were carried out in the 48 × 48 m plot: shoot height, shoot diameter, basal area and foliage cover of each individuals in the high shrub layer. Correlation analysis confirmed that significant positive relations were between mean H, mean DSH of the dominant woody species (Acer campestre, Acer tataricum and Cornus mas) and oak tree density between 1972 and 2017. The decreasing oak tree density did not show detectable impact to the co-dominant shrubs growth. There was a low significant association between number of oak trees and basal area of high shrub layer. Finally, there was a statistically significant interaction between mean cover of A. campestre and C. mas and oak trees. The findings of the study indicate that forest responded to oak decline with significant structural rearrangement in the shrub layer.

Influence of forest decline on the abundance and diversity of Raphidioptera and Mecoptera species dwelling in oak canopies

Trees in a state of decline exhibit a reduced foliage density and accumulate dead branches in their crowns. Consequently, forest decline can markedly affect both the habitats and sources of food for canopy-dwelling insects. The decline-induced increase in canopy openness may also modify the understory, shrub and ground layers, and have cascading effects on associated species. Flight interception traps and green Lindgren traps were used to survey the canopy-dwelling insects in stands of healthy and declining oak trees, in particular two insect orders: Raphidioptera, saproxylic insects associated with canopies, and Mecoptera, necrophagous or opportunistic species associated with the herbaceous or shrub strata. Overall, green Lindgren traps caught more of these insects than flight interception traps. The traps caught five species of Raphidioptera. Three of them, Subilla confinis, Phaeostigma major and, to a lesser extent, Phaeostigma notata, were more abundant in stands or plots with declining trees. However, the other two species of Raphidioptera, Atlantoraphidia maculicollis and Xanthostigma xanthostigma exhibited a reverse trend. Two species of Mecoptera, Panorpa germanica and Panorpa communis, were particularly abundant, but unaffected by the level of decline. Our results show that declining forests can either host more or fewer species of Raphidioptera with saproxylic larvae, whereas Mecoptera with ground-living larvae were unaffected. Seasonal phenology and sex ratio of the species are also discussed.

Bird community changes associated with cattle raising management in the delta forests of the Paraná River

Riparian forests and environments close to watercourses support high biodiversity, which may be modified by human activities. In the Paraná River Delta region, cattle raising is one of the activities with the greatest impact, altering vegetation structure. These changes are reflected in bird communities that inhabit these environments. We hypothesize that the absence of large herbivores (whether cows or native deer) will produce an increase in the vegetation cover of the lower strata of forests, due to the greater height of the herbaceous stratum and greater coverage of the shrub stratum, and that these changes mainly affect the species of birds that use resources associated with these strata. Our objective was to understand the changes in richness and abundance of the bird community among different types of cattle management using a functional aggregation approach of bird species. In the areas with cattle, we found less coverage of the shrub layer, lower height of the herbaceous layer and fewer climbing vines. We found that changes in richness and abundance of bird community were strongly related to species associated with the lower vegetation strata (ground-feeding guild, shrub guild and low canopy guild), and that the responses of the different guilds were not homogeneous. Understanding the direction of changes in bird communities occurring in response to modifications of the environment, allows us to optimize conservation efforts. If these efforts are based on conservation of the environment in its natural state, we should adjust the management of the herbivory to the pristine conditions of the environment. On the other hand, if conservation efforts are based on particular species or groups of species associated with certain resources, the correct management of herbivory by cattle can be essential to obtain successful results.