Explore the vast range of titles available.

1. Variable-retention harvest is widely recognized as an alternative to more intensive methods such as clear-cutting. However, present information is inadequate to judge the impact of variable retention on biodiversity of indigenous forest organisms intolerant of canopy removal, such as forest-inhabiting bryophytes. 2. We examined how bryophyte species cover, richness, diversity and composition change with time in response to a broad range of dispersed retention harvest treatments (2% [clear-cut], 10%, 20%, 50%, 75% retention of original basal area) contrasted with uncut controls [100% retention]) in broadleaf deciduous, mixedwood and conifer-dominated boreal forests in North West Alberta, Canada. Bryophytes were studied in 432 permanent sample plots within 72 compartments before harvest and at 3, 6 and 11 years after harvest. 3. Clear-cut and lower (10% and 20%) retention levels resulted in lower cover and richness of bryophytes than in unharvested control compartments in mixed and conifer-dominated forests, but less so in deciduous-dominated forests, which generally supported low cover and richness. Species composition in each forest type varied along the gradient of harvesting intensity; clear-cuts and lower levels of retention supported similar composition, as did control plots and those representing higher retention levels. Over time, the retention harvest treatments became more similar to uncut controls. 4. Synthesis and applications. Variable-retention harvests can better maintain bryophyte biodiversity in managed boreal mixedwood forests, as compared to clearcuts. We found the efficacy of retention harvest scaled with harvest intensity. Higher levels of retention better moderated the negative impacts of harvesting on bryophyte assemblages across all forest types. Our results suggest, however, that even 10% retention will facilitate faster post-harvest recovery of bryophytes, as compared to clear-cutting.

The purpose of this study was to quantify the effects of clear‐cutting and site preparation on dissolved organic carbon (DOC) concentrations and export in four boreal headwater streams in northern Sweden. The data set included intensive stream water monitoring from 2 years of pretreatment conditions (2004–2005), a 2 year post‐clear‐cut period (2006–2007), and a 2 year period after site preparation (2008–2009). To investigate differences in [DOC], an analysis of variance on ranks was performed on the data sets. Clear‐cutting increased the median DOC concentrations significantly from 15.9 to 20.4 mg L−1, which represents a net increase (treatment versus control) of 3.0 mg L−1 in the 2006–2007 period. Site preparation had an even more profound effect on DOC levels; an increase from 20.4 to 27.6 mg L−1was found in the site‐prepared catchments, whereas the control sites increased slightly from 17.4 to 21.4 mg L−1during the wetter years of 2008–2009. Riverine C fluxes increased significantly by 100% after clear‐cutting and by 79% after site preparation (92% and 195%, respectively, if compared to pretreatment conditions). When comparing these yearly C fluxes (183 kg C ha−1 yr−1after clear‐cutting; 280 kg C ha−1 yr−1after site preparation) to the net ecosystem exchange (NEE) of a forest in the region, the DOC flux represented 10% of NEE before harvest, increased to 18% after the clear‐cut, and increased to 28% after site preparation. These results underline the large impact of forestry operations on stream water quality as well as DOC exports leaving managed boreal forests. Key Points Forestry operations increase stream DOC concentrations significantly Forestry operations increase riverine DOC export by up to 100% Riverine DOC exports account for up to 28% of NEE after forestry operations

The semideciduous forest is a prominent yet highly degraded phytophysiognomy within the Atlantic Forest. Historically, bird species inhabiting these forests occurred throughout central and western São Paulo state, south‐eastern Brazil, until the mid‐20th century. Many of these species have not been observed again or are nearing extinction within the state's inland forest fragments. This study reviews and compares historical and recent ornithological records, using museum specimens, literature, citizen science and recent field surveys to understand these species' current lack of records. In the early 20th century, extensive deforestation occurred statewide, resulting in the current forest fragments, which are currently in various stages of regeneration, conservation and isolation. Many of these fragments lack the specific habitats some species require, or they have not been recolonised due to insufficient connectivity with other forest fragments where these species still exist (particularly in the eastern Atlantic Forest). The non‐detection of forest species in semideciduous forest fragments strongly suggests an unprecedented and largely unnoticed extinction scale. This pattern of defaunation, as predicted 30 years ago, may be prevalent across numerous Semideciduous Atlantic Forests in Brazil. Due to near total deforestation in much of the Brazilian state of São Paulo in the early 20th century, essentially all non‐coastal and not montane forest fragments today are regenerated. Before deforestation, most Atlantic Forest endemic bird species were found throughout the state, as demonstrated by museum specimens and the previous literature. Currently, endemics are not reported from western fragments, as illustrated by the recent literature (post‐1990s), citizen science data and our recent field inventories.

1. The extent to which tropical rain forests recover tree species richness, composition and community structure after clear-cutting or selective harvest is controversial. Thus, the conservation value of forests regenerated after harvest remains unclear, but critically important for biodiversity. 2. We sampled trees from 164 25 × 25 m quadrats across a 160-km² tropical rain forest landscape on Hainan Island, China, which had been clear-cut or selectively harvested and left to recover without management for up to 50 years. Species richness and species abundance distributions were compared among five successional categories to investigate changes in species richness and species abundance over time. Basal areas and three different species similarity indices were compared to reveal temporal changes in species composition and community structure. 3. Species richness recovered faster than species composition and structure in both selectively logged and clear-cut forests. Both total number of species and number of rare species tended to increase from younger harvested forests through older harvested forests to old-growth intact forests. Within 20-40 years after harvest species composition of harvested forests tended towards that of old-growth forests, community similarity between harvested and oldgrowth forests decreased subsequently and basal area did not recover, given even a half-century of succession undisturbed by anthropogenic forces. 4. Shortly after harvest, pioneer species increased rapidly, but shade-tolerant species required much more time to recover to former abundances. The shift from pioneer species to shadetolerant species indicates significant recovery of logged forests. 5. Selectively logged forests recovered more quickly and had higher conservation values than clear-cut forests. 6. Synthesis and applications. Our findings indicate that logged tropical forests only partially recovered the characteristics of pre-harvest, primary forest after a half-century of succession. Recovery of the original tree biodiversity on such post-harvest landscapes will be slow at best, if measured by species composition or stand structure. Our study amplifies the importance of conserving tropical forest integrity and developing harvest and management approaches that facilitate full recovery of logged tropical forests.

QUESTIONS: What are the relative roles of disturbance type and canopy composition on understorey plant assemblages? Are these two environmental filters of equal importance in driving understorey patterns? Does a trait‐based approach improve understanding of plant assemblage responses in disturbed boreal forests? LOCATION: Eastern boreal forests of North America, Québec, Canada. METHODS: We sampled understorey plant assemblages in ca. 30‐yr‐old forest stands originating from three types of disturbance (clear‐cutting, fire and spruce budworm outbreak) and two dominant canopy compositions (coniferous and deciduous). For each disturbance × canopy combination, at least eight stands were sampled. The results were analysed with a combination of multivariate (RDA, PERMANOVA), univariate (IndVal) and trait‐based (fourth‐corner) approaches. RESULTS: Overall, canopy composition was a more important driver than disturbance type for understorey plant communities. Species richness and particularly the abundance of herbaceous species were highest under deciduous canopies, whereas bryophytes and lichens were more diverse and abundant under coniferous canopies. Light‐demanding species with abundant seed production were mostly restricted to deciduous canopies. Some patterns were also explained by disturbance type, but these were mostly associated with the presence/absence of non‐abundant species or species groups such as lichens. CONCLUSIONS: We propose that the higher effect of canopy composition compared with disturbance type can be explained by two factors. First, the effect of canopy composition tends to remain present for decades during stand development, whereas the effect of the disturbance type tends to dissipate progressively after the stand‐initiating disturbance. Second, in boreal forests, most understorey plant species possess reproduction strategies (such as vegetative reproduction) that make them well adapted to persist in stands affected by any type of disturbance. At the landscape level, maintaining the right proportion of deciduous and coniferous stands through forest management could ensure that understorey ecosystem processes and plant diversity are maintained. However, creating or maintaining specific post‐disturbance attributes could be important for the conservation of species affiliated with specific substrates.

1. There is a risk that short-term studies either underestimate disturbance effects because of time-lagged responses, including both time-lagged extinctions and colonizations, or overestimate them because of fast recovery. 2. To evaluate the conservation effectiveness of tree group retention (in this case, buffer strips along streams), we studied the bryophyte community once prior to, and twice after logging, comparing one buffer and one clear-cut plot (0·1 ha) in each of 13 riparian sites. We asked whether time-lagged responses or recovery processes had dominated the period between two re-inventories, 2·5 and 10·5 years after logging, focusing both on the whole community and on species of conservation concern. 3. Although there were examples of recovering species in both clear-cuts and buffer strips, the similarity in species composition to predisturbance conditions had decreased in the second re-inventory. Even if the buffer strips displayed more time-lagged colonizations and local extinctions over the later period compared to the clear-cuts, the overall species composition in the buffer strips was still significantly more similar to the prelogging conditions than the clear-cuts. 4. The red-listed species had mostly declined during the first period, and the number of red-list species per plot (mostly species growing on dead wood) was rather stable at <20% of predisturbance levels in clear-cuts and <60% in buffer strips in the last re-inventory. 5. Synthesis and applications. We show that most extinctions of red-list species occurred soon after disturbance and that the conclusions drawn from a study carried out 2·5 years after the disturbance did not change profoundly 8 years later. Although the species composition in the buffer strips continued to change over time, sensitive species survived much better in buffer strips than in clear-cuts, which supports the practice of retaining buffer strips for terrestrial species too. This knowledge should encourage managers to find ways of increasing the efficacy of this practice. One obvious measure could be to retain wider strips or implement other management practices that make the buffer strips less sensitive to wind, which will lead to higher tree retention to support a prelogging species composition.

Understanding the changes in the plant community and soil nitrogen (N) availability during natural recovery of a forest following clear-cutting is critical to develop post-disturbance forest management strategies. Therefore, post-clearcut changes in vegetation, net N mineralization rates and available N concentrations in soil were studied in a montane subtropical broadleaved forest during the early years of recovery following a chronosequence approach. Two replicate stands were selected for each treatment of old-growth undisturbed forest and recovering forest stands aged 1, 5 and 10 years. Following disturbance, tree species diversity and basal area declined but shrub and herb diversity increased. High percentage dissimilarity among the stands in tree, shrub and herb species composition indicated that species colonization varied with recovery age. NH₄ ⁺-N and NO₃ ⁻-N concentrations increased significantly (P < 0.001) following clear-cutting and the increasing trend continued until 5 years post-recovery, after which it declined. While ammonification rate remained unchanged with recovery age, nitrification and net N mineralization rates in 10-year-old and undisturbed forest were significantly greater (P < 0.001) than in 1- and 5-year-old forest, indicating that mineralization rates increased with recovery age. Despite high mineralization rates, low availability of soil N in the later years of recovery was attributed to high N uptake by growing vegetation and leaching because of high rainfall in Cherrapunjee. To ensure N availability during the later years of recovery, we suggest that forest management intervention should encourage aided regeneration of native N-fixing trees, e.g., Myrica esculenta, during the initial years of recovery.

Coarse woody debris (CWD) is an important contributor to forest biodiversity because it provides essential habitat for saproxylic (dead wood‐dependent) species. However, CWD is frequently overlooked in forest management and restoration decisions around the world. We have therefore developed an index of CWD habitat quality that integrates four important characteristics of saproxylic habitat. We apply this index to wet eucalypt forests in Tasmania, Australia. The relationships between the CWD index and standing forest structural and floristic maturity metrics were weak (R2 < .09), highlighting the necessity to explicitly factor CWD habitat into conservation planning. A hump‐shaped relationship between current CWD habitat quality and variables linked to future quality (standing tree basal area and the number of old‐growth eucalypts) implies that stands with medium current quality provide better potential future habitat than stands with high current quality. CWD habitat quality was lower in previously harvested stands. We present a web app that calculates CWD habitat quality scores from raw field measurements. Our approach can be applied in conservation assessments to determine habitat availability for biodiversity, and to quantify the impacts of management actions and restoration activities.

In many cases tree felling and processing operations are carried out motor-manually and knowledge about fossil fuel consumption and direct energy inputs when using such equipment is required for different purposes starting with operational costing and ending with environmental assessment of forest operations. In this study, fuel mixture, chain oil and direct fossil energy inputs were evaluated for two chainsaws which were used to fell and process trees in two silvicultural systems. The results of this study suggest that there is a strong dependence relation between selected tree size variables such as the diameter at breast height and tree volume on one hand and the fuel mixture, chain oil and direct fossil energy inputs when felling and processing broadleaved hardwood and resinous softwood trees on the other hand. For the broadleaved trees (mean tree volume of 1.50 m3 × tree-1, DBH of 45.5 cm and tree height of 21.84 m) the mean direct fossil energy input was of 3.86 MJ m-3 while for resinous trees (mean tree volume of 1.77 m3 tree-1, DBH of 39.28 cm and tree height of 32.49 m) it was of 3.93 MJ m-3. Other variables, including but not limited to the technology used, work experience and procedural pattern, may influence the mentioned figures and extensive studies are required to clarify their effects.

Clear-cutting practices in hemiboreal forests significantly alter forest ecosystems, leading to substantial changes in soil carbon and nitrogen dynamics. This study investigated the impact of clear-cutting age on soil organic carbon (SOC) and total nitrogen (TN) focusing on soil microbial biomass carbon (SMBC), soil microbial biomass nitrogen (SMBN), and soil microbial respiration in the mineral topsoil 0-10 cm and 10-20 cm layers. The study sites included 1st-, 2nd-, and 3rd-year clear-cut sites, and adjacent mature Scots pine stand sites, adopting a paired-site design to compare clear-cuts of different ages and forest sites. Clear-cutting in Scots pine forests significantly impacted SOC and TN concentrations, initially leading to a decrease in SOC followed by an increase in TN levels. We found higher concentrations of nitrate (NO3-N), nitrite (NO2-N), and ammonium (NH4-N) in clear-cuts compared to mature forests, indicating enhanced nitrification and mineralization processes after clear-cut. The SOC and TN stocks were higher in the forest topsoil layers than in the clear-cut sites, except for the TN values in the 3rd-year clear-cuts. The SMBC concentrations were higher in forests than in clear-cuts, which showed the importance of forest ecosystems in supporting microbial activity and soil health. Variations in the SOC:TN and SMBC:SMBN ratios between forests and clear-cuts suggested alterations in soil nutrient dynamics and microbial community structure resulting from the clear-cutting of mature forests. We concluded that further research is needed to understand better the long-term impacts of clear-cutting on soil quality and the status of reforested ecosystems, while evaluating the interactions between soil chemical and biological properties as more effective indicators.