•Species richness and diversity peaked 15 years after forest harvesting.•A shelterwood increased Vaccinium shrub cover more than other systems.•Silvicultural system had a greater effect on 26-year ...shrub cover than early control.•Forest floor bryophyte cover remains one-third or less than pre-harvest cover.•Retention patches (0.8–0.9 ha) retained late-seral species with few edge effects.
This study is one of several investigating the biological effects of silvicultural systems at the Montane Alternative Silvicultural Systems (MASS) project located on Vancouver Island in British Columbia (BC). We compared understory vegetation cover and diversity under four silvicultural systems (clearcutting, patch cutting, dispersed retention, and shelterwood) to an adjacent old-growth forest. Long-term plots were measured pre-harvest and at intervals up to 26 years post-harvest. We also compared vegetation response to fertilization and vegetation control treatments. All harvesting resulted in a short-term reduction in understory cover from logging debris and ground disturbance. Recovery from disturbance varied by species, life-form and system. Understory tree species returned to pre-harvest cover after 15 years and significantly exceeded initial cover after 26 years. Shrubs returned to pre-harvest cover after 5–10 years and continued to increase in most systems. Herb cover was low in the pre-harvest forest but increased rapidly in years three through 10 due to herbaceous colonizers; this was least pronounced in the shelterwood. Herbs have declined rapidly since year fifteen. Forest floor bryophytes were reduced to less than 5% cover in all systems except the shelterwood and they remain at one-third or less of their pre-harvest cover. The shelterwood retained more stand structure and plant species from the original old-growth forest than other systems immediately after logging, except for the retained patches. All the harvesting treatments increased species richness and diversity compared to the pre-harvest forest. The increase in total species and abundance was highest for year 15 when early-seral colonizers were still present, and many pre-harvest species had returned. By year 26, richness and diversity began to decrease as early-seral species were lost. For overall species diversity of vascular plants and forest floor bryophytes, silvicultural system did not have an effect after 26 years. All the late-seral herbs that occur at MASS were present after harvesting but several were locally eliminated or had reduced abundance in cut areas. We found no significant edge effects into retention patches, which had comparable species richness and diversity to the pre-harvest old growth—suggesting that aggregated retention can be effective for maintaining late-seral species. Silvicultural system had more significant long-term effects on shrubs and bryophytes than early vegetation control.
The seasonal succession of plankton is an annually repeated process of community assembly during which all major external factors and internal interactions shaping communities can be studied. A ...quarter of a century ago, the state of this understanding was described by the verbal plankton ecology group (PEG) model. It emphasized the role of physical factors, grazing and nutrient limitation for phytoplankton, and the role of food limitation and fish predation for zooplankton. Although originally targeted at lake ecosystems, it was also adopted by marine plankton ecologists. Since then, a suite of ecological interactions previously underestimated in importance have become research foci: overwintering of key organisms, the microbial food web, parasitism, and food quality as a limiting factor and an extended role of higher order predators. A review of the impact of these novel interactions on plankton seasonal succession reveals limited effects on gross seasonal biomass patterns, but strong effects on species replacements.
Together with plants, soil microbial communities play an essential role in the development of stable ecosystems on degraded lands, such as postmining spoil heaps. Our study addressed concurrent ...development of the vegetation and soil fungal and bacterial communities in the course of primary succession in a brown coal mine spoil deposit area in the Czech Republic across a chronosequence spanning 54 years. During succession, the plant communities changed from sparse plants over grassland and shrubland into a forest, becoming substantially more diverse with time. Microbial biomass increased until the 21st year of ecosystem development and later decreased. Although there was a close association between fungi and vegetation, with fungi mirroring the differences in plant community assemblages, the development of the bacterial community was different. The early succession community in the barren nonvegetated soil largely differed from that in the older sites, especially in its high abundance of autotrophic and free‐living N2‐fixing bacteria. Later in succession, bacterial community changes were minor and reflected the chemical parameters of the soil, including pH, which also showed a minor change with time. Our results show that complex forest ecosystems developed over 54 years on the originally barren soil of the temperate zone and indicate an important role of bacteria in the initial stage of soil development. Although the arrival of vegetation affects substantially fungal as well as bacterial communities, it is mainly fungi that respond to the ongoing development of vegetation.
Aims
Selective browsing can be a chronic disturbance that reduces the survival, growth and reproduction of individual species and shapes the composition and structure of plant communities. Along with ...other disturbances that perturb the forest ecosystem, browsing may thus affect forest regeneration and successional trajectories after an acute perturbation such as clear‐cutting. However, effects of different browsing pressures on plant species, communities and ultimately succession remain hard to predict.
Methods
We implemented a browsing exclusion experiment (n = 15 sites) along a gradient of moose browsing pressure to investigate how this factor influenced the early‐successional trajectory of boreal forests following clear‐cutting in eastern Canada. We used Principal Response Curve analyses to compare the trajectory of the plant communities depending on site‐specific moose browsing pressure and analyzed the trajectory of individual species leveraging these curves.
Results
Our results show that all browsing pressures lead to alterations in plant communities when compared to exclosures, but the effect was stronger under heavier browsing pressure. Under heavier browsing pressure, we observed a lower ground cover of balsam fir, an increased ground cover of raspberry, reaching more than 60%, and a lower abundance of saplings for balsam fir, birches and rowan.
Conclusions
This study demonstrated that forest response to browsing is a function of local browsing pressure and that moose mainly slowed forest succession toward a closed canopy. However, heavier browsing pressure, through reduced sapling abundance and the resulting increased cover of competitive raspberry, may delay forest succession and push the ecosystem toward an alternative successional trajectory. As heavy selective browsing can interact with anthropogenic disturbances to determine forest succession, we recommend strong integration of the forest and wildlife management sectors to promote sustainability.
How different levels of browsing pressure affect forest succession remains hard to predict. We used a browsing exclusion experiment to investigate the effects of various moose browsing pressures on forest succession. Results show that moose mainly slows succession but heavier browsing could trigger an alternative successional trajectory.
Although plants of the genus
can accelerate the removal of atrazine from its rhizosphere, the roles played by this plant in adjusting the soil environment and soil microorganism properties that might ...contribute to pollutant removal are incompletely understood. We selected
(L.) K. Schum (
) as the test plant and investigated the interaction between
and atrazine-contaminated soil, focusing on the adjustment of the soil biochemical properties as well as bacterial functional and community diversity in the rhizosphere using Biolog EcoPlates and high-throughput sequencing of the 16S rRNA gene. The results demonstrate that the rhizosphere soil of
exhibited higher catalase activity, urease activity and water soluble organic carbon (WSOC) content, as well as a suitable pH for microorganisms after a 28-day incubation. The bacterial functional diversity indices (Shannon and McIntosh) for rhizosphere soil were 3.17 ± 0.04 and 6.43 ± 0.86 respectively, while these indices for non-rhizosphere soil were 2.95 ± 0.06 and 3.98 ± 0.27. Thus, bacteria in the
rhizosphere exhibited better carbon substrate utilization than non-rhizosphere bacteria. Though atrazine decreased the richness of the soil bacterial community, rhizosphere soil had higher bacterial community traits. For example, the Shannon diversity indices for rhizosphere and non-rhizosphere soil were 5.821 and 5.670 respectively. Meanwhile, some bacteria, such as those of the genera
,
,
, and
, which facilitate soil nutrient cycling or organic pollutants degradation, were only found in rhizosphere soil after a 28-day remediation. Moreover, redundancy analysis suggests that the soil biochemical properties that were adjusted by the test plant exhibited correlations with the bacterial community composition and functional diversity. These results suggest that the soil environment and bacterial properties could be adjusted by
during phytoremediation of atrazine-contaminated soil.
Post‐mining freshwater habitats can serve as secondary habitats for threatened species. Being globally plentiful, their efficient restoration should be based on detailed evidence, especially under ...the current global decline of freshwater biodiversity. Synthetic studies focusing on the effects of restoration on freshwater communities are surprisingly rare, even for the most common restoration approaches. Such a lack of evidence limits the efficiency of habitat restoration in post‐mining landscapes.
We combined a landscape‐scale field study of aquatic beetles and hemipterans in 29 freshwater pools at lignite spoil heaps in Czechia with a comparative synthesis of all 14 available datasets on freshwater communities at habitats created by coal mining in Central Europe. We compared the diversity and conservation value of freshwater habitats created by the main restoration approaches, including technical reclamation, spontaneous succession and their combination. Additionally, we analysed the detailed influence of key habitat descriptors on their conservation potential.
Communities of aquatic beetles and hemipterans had more species in spontaneously and semi‐spontaneously developed pools, which were also preferred by more red‐listed species of both studied groups. The reviewed studies showed the same trend for amphibians, odonates, dipterans and macrozoobenthos, although some technically created pools and drainage ditches harboured some threatened species of aquatic plants, odonates and macrozoobenthos as well.
Relatively independent of the restoration approach, the conservation value of freshwater communities was related to the particular characteristics of the restored habitats. The key beneficial features were as follows: smaller area of restored water bodies, heterogeneous littoral vegetation with suppressed dominants, heterogeneous bottom substrate with low and gradually sloping banks, absence of fish, sun‐exposed water surface and some forests in the surroundings.
Synthesis and applications. Efficient restoration of freshwater habitats at post‐mining landscapes can create important secondary refuges for threatened and common species. Freshwater communities of high conservation value can be supported by all main restoration approaches if heterogeneous habitats are created. A combination of technical reclamation with spontaneous succession seems to be the most efficient approach to maximise biodiversity in freshwater habitats at coal‐mining spoil heaps.
Efficient restoration of freshwater habitats at post‐mining landscapes can create important secondary refuges for threatened and common species. Freshwater communities of high conservation value can be supported by all main restoration approaches if heterogeneous habitats are created. A combination of technical reclamation with spontaneous succession seems to be the most efficient approach to maximise biodiversity in freshwater habitats at coal‐mining spoil heaps.
•Models for biomass and age relationship for different growth conditions were developed.•Models for organic and mineral soils across site types and biogeographical zones were presented.•The models ...present long-term averages of realized management in Finland.•The results highlight a trade-off between carbon sequestration and storage.
Information on carbon stocks and the rate of carbon accumulation is needed to harness the climate change mitigation potential of boreal forests. While previous studies have revealed general patterns and mechanisms for age-dependence of stand biomass, simple stand-level models that address the age-biomass relationship on average in managed boreal forests in different environmental conditions are largely missing. We developed models for the relationship between stand age and biomass by forest types on peatlands and mineral soils across climate zones in managed forests in Finland based on National Forest Inventory measurements from 1996 to 2018. In addition, we analyzed at which rate biomass accumulates when managed forest ages in different growth conditions. In northern Finland the maximum biomass change rate was one third, and the maximum biomass stock less than half of the corresponding values in sub-xeric heath forests on minerals soils in southern Finland. On drained peatlands the maximum biomass growth rate was approximately half, and on undrained peatlands one third of the maximum growth rate on mineral soils. On most fertile sites on mineral soils the maximum biomasses were three times larger than on the poorest sites. Correspondingly, the maximum biomass stock change rates were almost eight times faster on most fertile sites. In the example cases presented, the highest annual biomass change rates were achieved in young forests on average at the stand ages of 7–32 years, whereas the 95% of the maximum stock were reached on average in stands of 63–147 years. At the age of highest biomass growth rate stands contained 27–59% of the maximum biomass stocks. The developed models can be used in practical applications such as accounting of biogenic carbon in life-cycle assessments, mapping carbon, or creating simple predictions of biomass stock development in regions, or estimating the mitigation potential of afforestation and reforestation or estimating the magnitude of carbon offsets projects.
Second-growth tropical forests are an important global carbon sink. As current knowledge on biomass accumulation during secondary succession is heavily based on chronosequence studies, direct ...estimates of annual rates of biomass accumulation in monitored stands are largely unavailable. We evaluated the contributions of tree diameter increment, recruitment, and mortality to annual tree biomass change during succession for three groups of tree species: second-growth (SG) specialists, generalists, and old-growth (OG) specialists. We monitored six second-growth tropical forests that varied in stand age and two old-growth forests in northeastern Costa Rica. We monitored these over a period of 8 to 16 years. To assess rates of biomass change during secondary succession, we compared standing biomass and biomass dynamics between second-growth forest stages and old-growth forest, and evaluated the effect of stand age on standing biomass and biomass dynamics in second-growth forests.
Standing tree biomass increased with stand age during succession, whereas the rate of biomass change decreased. Biomass change was largely driven by tree diameter increment and mortality, with a minor contribution from recruitment. The relative importance of these demographic drivers shifted over succession. Biomass gain due to tree diameter increment decreased with stand age, whereas biomass loss due to mortality increased. In the age range of our second-growth forests, 10-41 years, SG specialists dominated tree biomass in second-growth forests. SG specialists, and to a lesser extent generalists, also dominated stand-level biomass increase due to tree diameter increment, whereas SG specialists largely accounted for decreases in biomass due to mortality.
Our results indicate that tree growth is largely driving biomass dynamics early in succession, whereas both growth and mortality are important later in succession. Biomass dynamics are largely accounted for by a few SG specialists and one generalist species,
Pentaclethra macroloba
. To assess the generality of our results, similar long-term studies should be compared across tropical forest landscapes.
Abstract
Open-cast coal-mining creates a severe disturbance of ecological systems, resulting in post-mining areas that have lost their soils entirely and are exposed to extreme conditions. ...Nonetheless, these areas allow us to investigate the process of primary succession. We studied the first 12 years of soil tardigrade succession at ‘Chicken Creek’, an experimental site within the open-cast coal-mining area in Welzow Süd, Germany. A total of ten tardigrade genera and 13 species or species groups were identified at the site. Over time, the organic carbon content, proportion of silt and nutrient availability in the soil increased, and the soil particle size distribution and pH value changed significantly. The vegetation cover and nematode abundance increased, whereas tardigrade densities peaked in 2008 and decreased thereafter, as did their mean body size. Species replacement was obvious within this 12 year study period, and tardigrade species diversity increased, indicating that ecological niche diversity also increased throughout this time. Vegetation cover, soil particle size distribution and time were the most important factors influencing the tardigrade community. We also discuss further potential factors and the ability of terrestrial tardigrades to persist despite many environmental constraints, such as fluctuations in pH and moisture, and to colonize new habitats faster than most other animal groups.
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