Progress and prospects in understanding the effects of forest management practices on soil nitrogen cycling

Agricultural and urban land use activities have affected stream ecosystems throughout the mid-Atlantic region. However, over 60% of the mid-Atlantic region is forested. A study was conducted to investigate the effects of management practices on forested stream ecosystems throughout the mid-Atlantic region. The study consisted of two phases: Phase 1 was a literature synthesis of information available on the effects of forest management practices on stream hydrology, erosion and sedimentation, riparian habitat alteration, chemical addition, and change in biotic diversity in the mid-Atlantic region. In Phase 2, data from mid-Atlantic streams were analyzed to assess the effects of forest land use on stream quality at the regional scale. Typically, it is the larger order streams in which monitoring and assessment occurs—3rd order or higher streams. The impacts of forest management practices, particularly hydrologic modifications and riparian buffer zone alteration, occur predominantly in first and second order streams with cumulative impacts translating to higher order streams. Based on the literature review and mid-Atlantic Highland streams analysis, there are short-term (e.g., 2 to 5 years) effects of forest management practices on stream quality at local scales. However, signatures of cumulative effects from forest management practices are not apparent at regional scales in the Highlands. In general, forested land use is associated with good stream quality in the region compared with other land use practices.

The red-shouldered hawk (Buteo lineatus) is a species of special concern throughout its northern range. It is considered to be sensitive to forest management practices because it requires dense mature hardwood forest for nesting. In Ontario, guidelines that prescribe spatial and temporal buffers were developed in about 1990 to mitigate the potential impacts of harvesting. We monitored 84 nesting areas of red-shouldered hawks in central and southeastern Ontario from 1988 to 1995 to describe the effects of forest management practices on the occupancy and productivity of nesting areas, to evaluate the effectiveness of the guidelines, and recommend modifications as appropriate. The number of years nesting areas had been used previously had a significant negative effect on activity status, but not on nest success. Nesting areas harvested with application of the guidelines had a similar probability of being active to those in uncut forest but nesting areas harvested without application of the guidelines did not. Neither the area nor proximity of selection cuts with a moderate to high residual basal area ( ≥18 m2/ha) affected the activity status of nesting areas. In contrast, the area and proximity of heavy cuts (shelterwood cuts or selection cuts with a residual basal area of 14–16 m2/ha) appeared to have a negative effect on activity status. When nesting areas were active, the proximity and amount of harvesting did not influence nest success. We concluded that the impact of harvesting on the activity status of nesting areas could be mitigated by prohibiting heavy cuts within 300 m of active nests and retaining ≥20 ha of forest dominated by tolerant and mid-tolerant hardwood trees, ≥18 m tall, with ≥70% canopy closure around nests. Key words: Buteo lineatus, effectiveness monitoring, habitat guidelines, nest success, Ontario, red-shouldered hawk, forest management, selection, shelterwood, tolerant hardwoods

Leaf litter decomposition is the key ecological process that determines the sustainability of managed forest ecosystems, however very few studies hitherto have investigated this process with respect to silvicultural management practices. The aims of the present study were to investigate the effects of forest management practices on leaf litter decomposition rates, nutrient dynamics (C, N, Mg, K, Ca, P) and the activity of ligninolytic enzymes. We approached these questions using a 473 day long litterbag experiment. We found that age-class beech and spruce forests (high forest management intensity) had significantly higher decomposition rates and nutrient release (most nutrients) than unmanaged deciduous forest reserves (P<0.05). The site with near-to-nature forest management (low forest management intensity) exhibited no significant differences in litter decomposition rate, C release, lignin decomposition, and C/N, lignin/N and ligninolytic enzyme patterns compared to the unmanaged deciduous forest reserves, but most nutrient dynamics examined in this study were significantly faster under such near-to-nature forest management practices. Analyzing the activities of ligninolytic enzymes provided evidence that different forest system management practices affect litter decomposition by changing microbial enzyme activities, at least over the investigated time frame of 473 days (laccase, P<0.0001; manganese peroxidase (MnP), P = 0.0260). Our results also indicate that lignin decomposition is the rate limiting step in leaf litter decomposition and that MnP is one of the key oxidative enzymes of litter degradation. We demonstrate here that forest system management practices can significantly affect important ecological processes and services such as decomposition and nutrient cycling.

Effects of forest management practices, weather, and indices of nest predator abundance on nest predation: A 12-year artificial nest study

Land development activities such as agriculture, clear cutting, peat mining, and the planting of forest plantations on wetlands can affect the hydrologic behavior of these ecosystems by affecting their water storage and release patterns on the landscape. The effects of these development activities on hydrologic fluxes in peatlands (Typic Medisaprists) were compared to the effects of forest management practices in North Carolina using a field-tested hydrologic simulation model (DRAINMOD). Simulations revealed that natural peat-based (Histosol) pocosin systems lose 66% (80 cm) of the 123 cm of average annual rainfall by evapo-transpiration (ET) and 34% (42 cm/yr) via annual runoff. Annual runoff values were 63 cm/yr for peat mining areas, 48 cm/yr for cleared peatlands, 46 cm/yr for peatlands converted to agriculture and 34 cm/yr for pine plantations, once the forest canopy is closed. Thus, these wetland alterations, except for forestry, significantly increased runoff and decreased ET compared to the natural ecosystem. Forest pine plantation management decreased runoff and increased ET. A case study of the effects of forest management practices was reviewed for a 15-year-old drained loblolly pine plantation growing on fine sandy loam soils (Thermic Typic umbraquults) in the coastal plains of North Carolina. Forestry activities such as thinning (i.e., reduced leaf area index by 50%) decreased ET and canopy interception and nearly doubled drainage loss (38 cm/yr to 60 cm/yr). Commonly applied forest practices, such as drainage, increased the average number of flow events with flows > 5 mm/day to 86 days per year from 26 days per year under natural conditions.

Boreal forests hold about 32% of the global forest carbon (C) stock and the majority of this C is stored in the soil. Forest management affects species composition, microclimate, plant growth, and litter production, and thus affects the soil organic carbon (SOC) storage. Hence, it is important to understand the effects of forest management practices on SOC storage and to adopt management strategies that protect SOC storage.We aimed to assess how two major forest management approaches differ in their impact on SOC quality and degradability to evaluate their effects on long-term SOC storage. Rotation forest management (RFM) based on clear-cut harvesting is the most common forest management practice worldwide. Continuous-cover forestry (CCF) as an integrated forest management approach has been suggested to enhance SOC storage. It uses repeated partial harvesting and retains a continuous tree cover.We present our recently published results from a field study in Ruunaa, Lieksa, eastern Finland. We compared the effects of logging methods applied in CCF and RFM on SOC storage and quality in boreal Scots pine (Pinus sylvestris) dominated forests ten years after the logging operations. We sampled&amp;#160;gap-cuts as logging method applied in CCF, retention-cuts (20% of tree volume retained), and uncut mature forests and clear-cuts as two opposing stages of RFM. We tested the hypotheses: (1) colder microclimate and continuous litter input lead to higher SOC stocks in CCF plots than in clear-cuts and (2) more labile litter of grass- and herb-rich vegetation typical for clear-cut sites enhances SOC decomposition rates. We analyzed the SOC concentration and stock and modelled annual above- and belowground litter inputs based on stand characteristics (diameter at breast height, basal area, dominant tree height, understory species coverage). We used sequential chemical fractionation of organic layer samples and laboratory incubation to analyze the quality of SOC and its degradability under standardized conditions. To estimate the decomposition rate as impacted by the environment we incubated cellulose bags in situ. We assessed the impact of varying microclimate with field measurements of soil temperature and soil moisture. We analyzed the microbial biomass C pool with chloroform fumigation extraction.The SOC content and stock did not differ significantly between the treatments, despite the warmer microclimate and lower litter input recorded in clear-cut plots than in CCF plots. However, we detected differences in quality and degradability of SOC. Soils in clear-cut sites held lower proportions of labile SOC compounds than the other treatments. As hypothesized, decomposition rate was elevated in clear-cuts, but was equally high within the canopy gaps of gap-cuts. Accumulation of labile SOC due to cooler microclimate, combined with decreased decomposition rate &amp;#8211; both found in uncut forests and retention-cuts &amp;#8211; indicate a higher potential for future SOC accumulation in these treatments than in clear-cuts. Our study highlights that forest management affects the quality, degradability, long-term accumulation and storage of SOC. Thus, the chosen logging method can be an important tool in climate change mitigation and the forest management regime needs to be adapted accordingly.&amp;#160;Publication in Forest Ecology and Management [2023]: https://doi.org/10.1016/j.foreco.2023.121144

Forest management can affect both the functioning and stability of ecosystems. Constancy and persistence are key factors that contribute to the overall stability of an ecosystem. These factors can be highly variable and change across forest ecosystems. We studied the effects of forest management on the strength of resource–consumer interactions (bird predation and insect herbivory) as important measures of ecosystem functioning, as well as on their constancy in time in four different forested regions globally. Within each region, we selected (i) three heavily managed or plantation forests, and (ii) three urban/peri-urban forests or urban plantings, and paired each of them with pristine/semi-natural forests. Bird predation was estimated using plasticine caterpillars of different colors. Chewer, galler, and miner herbivory on leaves were estimated for 15 plants (shrubs and trees) per study site. Constancy was quantified as the invariability of both predation and herbivory during a period of three (exceptionally two) years. We found no consistent responses of either predation or herbivory to forest management practices across study regions. Bird predation was higher in urban/peri-urban forests than in pristine/semi-natural forests in Patagonian and boreal forest, with intermediate levels of predation in managed or plantation forests. These differences might be explained by the increase of resource availability during the winters and by the higher abundances of generalist predators due to increase of temperatures (i.e., urban heat effect), for those regions where winter temperatures could be a limiting factor. Chewing insect herbivory was lower in urban/peri-urban forests, probably due to the exclusion of certain herbivores in response to warming and the higher predation pressure relative to pristine forests. No differences were found in other types of herbivory, indicating that effects of urbanization are guild-specific. In addition, we consistently found no effects of forest management practices on predation invariability and herbivory, thereby demonstrating the high constancy of ecosystem functioning to different forest management practices across regions. These findings advance our knowledge of the generalized effects of forest management on ecosystem functions and stability by establishing a connection between the ecology and management and conservation of plantations and natural forests.

Identifying performance indicators of the effects of forest management on ground-active arthropod biodiversity using hierarchical partitioning and partial canonical correspondence analysis

Impacts of forest management practices on soil carbon (C) and nitrogen (N) dynamics remain under debate due to complex interactions between belowground biogeochemical processes. To optimize practices that minimize soil C and N losses, we investigated the effects of management practices on soil C and N fluxes, including the leaching of dissolved organic C (DOC) and N, by comparing clearcutting, stem girdling (removal of the bark and phloem tissue), and control treatments in a Japanese cedar plantation. Canopy opening by clearcutting is hypothesized to have a greater effect on soil C loss and the leaching of nitrate-N relative to girdling. Results showed that clearcutting increased soil heterotrophic respiration (organic matter decomposition) and lead to a loss of soil organic C (2.9–3.7 Mg C ha−1 yr−1). Higher litter inputs from girdled tree dieback caused an increase in DOC fluxes from the organic horizon, whereas the loss of fresh litter inputs decreased DOC fluxes from the organic horizon following clearcutting. Clearcutting increased nitrate-N leaching by 3.3–4.8 kg N ha−1 yr−1 due to the loss of plant N uptake and the increased mineralization of soil organic matter, but high C/N ratios in dissolved organic matter limited nitrate leaching in the girdled treatment. Effects of forest management practices on soil C loss and nitrate leaching loss could be variable, but the slash application in clearcutting and the slow dieback in stem girdling could mitigate soil C loss and nitrate leaching loss.

Effects of forest management practices on carbon dynamics of China's boreal forests under changing climates

Biodiversity in forests is strongly affected by forest management practices, such as clearcutting and aggregated retention. Therefore, the assessment of the effects of forest management on biodiversity is a major concern in forest ecology. In the present study, we aimed to characterize the effects of forest management practices, after one year, on the abundance, species richness, community composition, and functional groups of moths in forests. The moths were sampled in four different forest stands: three stands (clearcutting, aggregated retention, and no cutting) in a planted Japanese larch forest and one stand in a natural Mongolian oak forest. The results revealed that the moth communities changed in response to the changes in vegetation after the implementation of forest management practices, and clearcutting increased the abundance and species richness of herbivorous and warm-adapted species. The structure and function of moth communities were affected by the forest management practices such as clearcutting and aggregated retention, which were reflected by a decrease in community indices and change in moth community composition with changes in vegetation.

In future decades, initiatives on biomass-based energy development in Europe should reduce fossil fuel dependence and help to combat climate change as required by the conference of the parties 21. In this context, forest biomass can play a key role within the bioenergy sector due to its high growth potential. The use of forest biomass for energy has positive and negative effects on other ecosystem services, on stand characteristics, and on forest management practices. The aim of this study is to analyse the effects of forest bioenergy production on six ecosystem services (biodiversity, recreation, landscape aesthetics, carbon sequestration, soil erosion protection, water quality). These effects have been assessed by 80 experts in two countries (Italy and Turkey), considering two different forest management practices (clear-cutting of coppices and woody residue removal after felling in high forests). The results show that coppice clear-cutting has negative effects on almost all ecosystem services according to the experts’ opinions. The highest negative effects are on landscape aesthetics and soil protection. The effects of woody residue removal on biodiversity, carbon sequestration, soil erosion protection, and water quality are considered negative by the experts, while the effects on recreation activities and landscape aesthetics are considered positive. The highest negative effects of this forest management scenario are on soil protection and biodiversity. The experts’ opinions about the effects of forest management practices on ecosystem services can provide information to understand the environmental sustainability of bioenergy development in future years.

Context Forest management has impacts on bats worldwide. Given that many forest bats are threatened and that bats are important providers of ecosystem services, understanding the effects of forest management practices on their activity is fundamental for the implementation of conservation measures. Despite these important issues, studies on the effects of management practices on bats are scarce. Aims To propose management measures for coniferous production forests, to ensure sustainability of bat populations. Methods We evaluated bat species richness and activity during gestation, lactation and mating/swarming/dispersion seasons in differently managed pine stands to evaluate how vegetation structure influences those variables. Bat activity was surveyed using acoustic monitoring in 28 sampling plots within stands with distinct management records in Portugal. We also sampled arthropods using light traps to ascertain how prey availability influenced bat species richness and activity in those plots. Key results Bat species richness and activity varied along the three phenological seasons and were higher in autumn, when mating, swarming and dispersion from nurseries to hibernacula took place. Prey availability varied, but was higher during the lactation season. We hypothesise that the lower levels of bat species richness and activity registered during that period were due to a reduced availability of roosts, rather than food scarcity. Species richness was positively correlated with canopy cover and prey taxa richness, and negatively associated with dry branches cover. Total bat activity was positively correlated with tree height and prey taxa richness, and negatively associated with dry branches cover. The activity of edge-space foragers was positively associated with average tree height and prey taxa richness, while the activity of open-space foragers was negatively associated with dry branches cover. Conclusions Coniferous production forests are of great importance for bats during the mating/swarming/dispersion season. Canopy cover, dry branches cover, tree height and prey taxa richness influence bat species richness and activity as a whole, particularly the activity of open- and edge- foraging guilds. Implications Based on our results, two straightforward management actions should be implemented in coniferous production forests to increase their value for bat assemblages: the maintenance of old coniferous stands, and the cutting of dry branches at the subcanopy level.

Investigating the effects of fire disturbance on soil microbial diversity and nitrogen cycling is crucial for understanding the mechanisms underlying soil nitrogen cycling. This study examined the fire burn site of the Larix gmelinii forest in the Greater Khingan Mountains, Inner Mongolia, to analyze the impact of varying fire intensities on soil nitrogen, microbial communities, and the abundance of nitrogen cycle-related functional genes after three years. The results indicated the following findings: (1) Soil bulk density increased significantly following severe fires (7.06%~10.84%, p &lt; 0.05), whereas soil water content decreased with increasing fire intensity (6.62%~19.42%, p &lt; 0.05). The soil total nitrogen and ammonium nitrogen levels declined after heavy fires but increased after mild fires; (2) Mild fire burning significantly increased soil bacterial diversity, while heavy fire had a lesser effect. Dominant bacterial groups included Xanthobacteraceae, norank_o_norank_c_AD3, and norank_o_Elsterales. Norank_o_norank_c_AD3 abundance decreased with burn intensity (7.90% unburned, 3.02% mild fire, 2.70% heavy fire). Conversely, norank_o_Elsterales increased with burning (1.23% unburned, 5.66% mild fire, 5.48% heavy fire); (3) The abundance of nitrogen-fixing nifH functional genes decreased with increasing fire intensity, whereas nitrification functional genes amoA-AOA and amoA-AOB exhibited the opposite trend. Light-intensity fires increased the abundance of denitrification functional genes nirK, nirS, and nosZ, while heavy fires reduced their abundance; (4) The correlation analysis demonstrated a strong association between soil bacteria and denitrification functional genes nifH and amoA-AOA, with soil total nitrogen being a key factor influencing the nitrogen cycle-related functional genes. The primary bacterial groups involved in soil nitrogen cycling were Proteobacteria, Actinobacteria, and Chloroflexi. These findings play a critical role in promoting vegetation regeneration and rapid ecosystem restoration in fire-affected areas.

Genetic effects of forest management practices: Global synthesis and perspectives