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Understorey vegetation of Scots pine forests was studied along a 8-km transect running SE from a Cu/Ni smelter at Harjavalta, SW Finland.Long-term accumulation of heavy metals and sulphur in the forest ecosystem has drastically changed plant communities. Vegetation was almost absent up to a distance of 0.5 km from the smelter. The total coverage and the number of plant species increased with increasing distance from the smelter. Ordination by global non-metric multidimensionalscaling (GNMDS) indicated that the floristic composition was differentiated in response to the pollution level. The main compositional gradient of GNMDS was correlated with the heavy metal concentrations inthe organic soil layer and with the size of the overstorey trees. Vascular plants were more pollution-resistant than ground lichens, whereas mosses were the most sensitive plant group. In addition to heavy metals, nutrient imbalances and the considerably reduced water-holding capacity of the surface soil also restrict plant recolonisation on the degraded sites. [ABSTRACT FROM AUTHOR]

Small-scale element distribution in soil/plant-systems in patches ofEmpetrum nigrum (microsites) at heavy metal contaminated sites located 0.5 and 4 km from the copper/nickel smelter at Harjavalta was investigated. The Cu concentrations of E. nigrum varied between 12 and 2300 mg/kg dw and showed increasing accumulation with increasing tissueage. Stems contained more Cu than leaves of the same age. The distribution pattern of Ni and Pb in the above-ground biomass followed thatof Cu. Roots contained relatively low concentrations of all airborneheavy metals. In the soil, the highest concentrations of total Cu occurred in the humus (Oh) layer: on average 49,450 mg/kg dw at 0.5 km distance and 12,025 mg/kg dw at 4.0 km. Despite the extremely high Cuconcentrations in the topsoil, the concentrations in the mineral soil below a depth of 10 cm did not exceed 2.5 mg/kg dw at any site. [ABSTRACT FROM AUTHOR]

The Cu and Ni tolerance of 3- to 5-year-old cuttings of crowberry (Empetrum nigrum) were tested in controlled conditions. Six levels of Cu (0.1/100 mg l-1), five levels of Ni (0/100 mg l-1) and nine levels of Cu+Ni were applied. The elongation of the shoots, new shoot and root dry weights indicated an adverse effect of increasing Cu and Ni concentrations. At low Cu levels the addition of Ni decreased the dry weights more than at high Cu levels. The resultsshow that E. nigrum accumulated high concentrations of Cu and Ni mainly in old stem tissue, which contained a maximum of over 3000 mg kg-1 Cu and 1000 mg kg-1 Ni. The concentrations ofCu and Ni in E. nigrum were higher than those measured in plants growing in areas near to Cu/Ni smelters, but the accumulation pattern was similar. The survival of the cuttings was not affected suggesting that E. nigrum possesses an internal heavy metal tolerance. [ABSTRACT FROM AUTHOR]

The copper (Cu) resistance of 1-year-old seedlings of heather (Calluna vulgaris) was tested in a greenhouse experiment. The plant material originated from seeds collected from three peatland sites located 1.2 km to the NW, and 2.5 and 5.5 km to the NE of the Harjavalta Cu/nickel (Ni) smelter, SW Finland. The plants were watered with a nutrient solution containing five different levels of Cu (1, 10, 22, 46 and 100 mg l-1). Cu clearly decreased the length growth of shoots, shoot and root biomass of C. vulgaris. More than 50% of the seedlings exposed to the highest Cu treatment died. C. vulgaris accumulated high amounts of Cu, the living old roots containing a maximum of 2200 mg kg-1 Cu and the living stems 1300 mg kg-1 Cu. Discolouring leaves contained higher Cu concentrations than green leaves. The results indicate Cu accumulation in roots and root-to-shoot transport. Some differences were found between the responses ofthe three seed provenances, but none of the populations proved to bemore resistant to Cu than the others in all the measured responses. [ABSTRACT FROM AUTHOR]

The state of health of 30 Norway spruce (Picea abies L. Karst.) stands located on the uplifting coast of western Finland was examined in 1992. Relationships between crown condition, elemental concentrationsof the needles, organic layer properties and soil type were studied using sitewise data. The site scores along the first axis of the Principal Component Analysis for certain needle and organic layer variables were used as the site fertility index. The spruces in the study area showed a higher level of defoliation and this occurred in younger stands than elsewhere in southern Finland. Defoliation and discoloration correlated positively with stand age, and negatively with the site fertility index. Low N and Cu concentrations of the needles were found in older stands where spruces were highly defoliated and discolored. Boron concentrations of the needles were highest in these stands.Total N of organic layer and extractable S concentrations were negatively correlated with stand age, defoliation and discoloration. The results suggest that poor crown condition of the coastal spruce standsis related to natural soil factors such as periodic water-logging and low fertility. Long-lasting soil frost as a consequence of thin snow cover might be an additional stress factor impeding water and mineral nutrient uptake in the beginning of the growing season. [ABSTRACT FROM AUTHOR]

Understanding the drivers of community assembly is critical for predicting the future of biodiversity and ecosystem services. Ecological selection ubiquitously shapes communities by selecting for individuals with the most suitable trait combinations. Detecting selection types on key traits across environmental gradients and over time has the potential to reveal the underlying abiotic and biotic drivers of community dynamics. Here, we present a model-based predictive framework to quantify the multidimensional trait distributions of communities (community trait spaces), which we use to identify ecological selection types shaping communities along environmental gradients. We apply the framework to over 3600 boreal forest understory plant communities with results indicating that directional, stabilizing, and divergent selection all modify community trait distributions and that the selection type acting on individual traits may change over time. Our results provide novel and rare empirical evidence for divergent selection within a natural system. Our approach provides a framework for identifying key traits under selection and facilitates the detection of processes underlying community dynamics., (© 2024 The Author(s). Ecology published by Wiley Periodicals LLC on behalf of The Ecological Society of America.)

Protected areas are considered fundamental to counter biodiversity loss. However, evidence for their effectiveness in averting local extinctions remains scarce and taxonomically biased. We employ a robust counterfactual multi-taxon approach to compare occupancy patterns of 638 species, including birds (150), mammals (23), plants (39) and phytoplankton (426) between protected and unprotected sites across four decades in Finland. We find mixed impacts of protected areas, with only a small proportion of species explicitly benefiting from protection-mainly through slower rates of decline inside protected areas. The benefits of protection are enhanced for larger protected areas and are traceable to when the sites were protected, but are mostly unrelated to species conservation status or traits (size, climatic niche and threat status). Our results suggest that the current protected area network can partly contribute to slow down declines in occupancy rates, but alone will not suffice to halt the biodiversity crisis. Efforts aimed at improving coverage, connectivity and management will be key to enhance the effectiveness of protected areas towards bending the curve of biodiversity loss., (© 2023. Springer Nature Limited.)

Mosses take up nitrogen (N) mainly from precipitation through their surfaces, which makes them competent bioindicators of N deposition. We found positive relationships between the total N concentration (mossN%) of common terrestrial moss species (feather mosses Pleurozium schreberi and Hylocomium splendens, and a group of Dicranum species) and different forms of N deposition in 11-16 coniferous forests with low N deposition load in Finland. The mosses were collected either inside (Dicranum group) or both inside and outside (feather mosses) the forests. Deposition was monitored in situ as bulk deposition (BD) and stand throughfall (TF) and detected for ammonium (NH 4 + -N), nitrate (NO 3 - -N), dissolved organic N (DON), and total N (N tot , kg ha -1 yr -1 ). N tot deposition was lower in TF than BD indicating that tree canopies absorbed N from deposition in N limited boreal stands. However, mossN% was higher inside than outside the forests. In regression equations, inorganic N in BD predicted best the mossN% in openings, while DON in TF explained most variation of mossN% in forests. An asymptotic form of mossN% vs. TF N tot curves in forests and free NH 4 + -N accumulation in tissues in the southern plots suggested mosses were near the N saturation state already at the N tot deposition level of 3-5 kg ha -1 yr -1 . N leachate from ground litterfall apparently also contributed the N supply of mosses. Our study yielded new information on the sensitivity of boreal mosses to low N deposition and their response to different N forms in canopy TF entering moss layer. The equations predicting the N tot deposition with mossN% showed a good fit both in forest sites and openings, especially in case of P. schreberi. However, the open site mossN% is a preferable predictor of N deposition in monitoring studies to minimize the effect of tree canopies and N leachate from litterfall on the estimates., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Biological fixation of atmospheric nitrogen (N 2 ) by bryophyte-associated cyanobacteria is an important source of plant-available N in the boreal biome. Information on the factors that drive biological N 2 fixation (BNF) rates is needed in order to understand the N dynamics of forests under a changing climate. We assessed the potential of several cryptogam species (the feather mosses Hylocomium splendens and Pleurozium schreberi, a group of Dicranum bryophytes, two liverworts, and Cladina lichens) to serve as associates of cyanobacteria or other N 2 -fixing bacteria (diazotrophs) using acetylene reduction assay (ARA). We tested the hypotheses that the legacy of chronic atmospheric N deposition reduces BNF in the three bryophyte species, sampled from 12 coniferous forests located at latitudes 60-68° N in Finland. In addition, we tested the effect of moisture and temperature on BNF. All species studied showed a BNF signal in the north, with the highest rates in feather mosses. In moss samples taken along the north-south gradient with an increasing N bulk deposition from 0.8 to 4.4 kg ha -1  year -1 , we found a clear decrease in BNF in both feather mosses and Dicranum group. BNF turned off at N deposition of 3-4 kg ha -1  year -1 . Inorganic N (NH 4 -N + NO 3 -N) best predicted the BNF rate among regression models with different forms of N deposition as explanatory variables. However, in southern spruce stands, tree canopies modified the N in throughfall so that dissolved organic N (DON) leached from canopies compensated for inorganic N retained therein. Here, both DON and inorganic N negatively affected BNF in H. splendens. In laboratory experiments, BNF increased with increasing temperature and moisture. Our results suggest that even relatively low N deposition suppresses BNF in bryophyte-associated diazotrophs. Further, BNF could increase in northern low-deposition areas, especially if climate warming leads to moister conditions, as predicted., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Chronic nitrogen (N) deposition is a threat to biodiversity that results from the eutrophication of ecosystems. We studied long-term monitoring data from 28 forest sites with a total of 1,335 permanent forest floor vegetation plots from northern Fennoscandia to southern Italy to analyse temporal trends in vascular plant species cover and diversity. We found that the cover of plant species which prefer nutrient-poor soils (oligotrophic species) decreased the more the measured N deposition exceeded the empirical critical load (CL) for eutrophication effects (P = 0.002). Although species preferring nutrient-rich sites (eutrophic species) did not experience a significantly increase in cover (P = 0.440), in comparison to oligotrophic species they had a marginally higher proportion among new occurring species (P = 0.091). The observed gradual replacement of oligotrophic species by eutrophic species as a response to N deposition seems to be a general pattern, as it was consistent on the European scale. Contrary to species cover changes, neither the decrease in species richness nor of homogeneity correlated with nitrogen CL exceedance (ExCLemp N). We assume that the lack of diversity changes resulted from the restricted time period of our observations. Although existing habitat-specific empirical CL still hold some uncertainty, we exemplify that they are useful indicators for the sensitivity of forest floor vegetation to N deposition., (© 2013 John Wiley & Sons Ltd.)

The effect of nitrogen on biomass production, shoot elongation and relative density of the mosses Pleurozium schreberi, Hylocomium splendens and Dicranum polysetum was studied in a chamber experiment. Monocultures were exposed to 10 N levels ranging from 0.02 to 7.35 g N m(-2) during a 90-day period. All the growth responses were unimodal, but the species showed differences in the shape parameters of the curves. Hylocomium and Pleurozium achieved optimum biomass production at a lower N level than Dicranum. Pleurozium had the highest biomass production per tissue N concentration. Tolerance to N was the widest in Dicranum, whereas Hylocomium had the narrowest tolerance. Dicranum retained N less efficiently from precipitation than the other two species, which explained its deviating response. All species translocated some N from parent to new shoots. The results emphasize that the individual responses of bryophytes to N should be known when species are used as bioindicators.

The copper (Cu) resistance of Arctostaphylos uva-ursi was tested in a pot experiment (lasting 8 weeks) using rooted cuttings originating from an area near the Harjavalta Cu-Ni smelter, SW Finland. The fine roots were moderately infected by arbutoid mycorrhizae. The plants were exposed to five Cu levels (1, 10, 22, 46 and 100 mg l(-1)) given repeatedly together with a nutrient solution. The critical Cu concentration in the nutrient solution inhibiting the growth of A. uva-ursi was below 10 mg l(-1) Cu (EC(50) value for biomass production 3.3 mg l(-1) Cu). This concentration was clearly lower than the value we have found earlier for other dwarf shrubs under similar experimental conditions. Most of the Cu given accumulated in the roots and old stems. The results suggest that A. uva-ursi cuttings were relatively sensitive to Cu despite the ability of the adult clones to grow in Cu-contaminated soil. The adult clones extend their roots into the less toxic deeper soil layers, which may facilitate the avoidance of heavy metals.