Effects Of Silvicultural Treatments Research Articles

Evaluating effects of silvicultural treatments on forest canopy structure outcomes

Traditional forest management can homogenize forests, and management strategies that can restore complexity and promote adaptive capacity to global change are needed. However, effects of different silvicultural practices on complexity of forest structural components, such as the canopy, are not well understood mechanistically. We conducted a coupled field and simulation-modeling study to evaluate: 1) how near-term effects of silviculture on canopy structure and complexity differ across treatment types, and 2) how outcomes of common silvicultural treatments compare to a spectrum of randomly implemented removals. Thirteen different silvicultural treatments replicated across 12 study plots were simulated within 3D models derived from terrestrial lidar data. Treatment types often differed in their multi-dimensional structural outcomes, including vertical heterogeneity and canopy structural complexity. Moderate intensity thinning treatments that preferentially removed smaller trees increased near-term canopy structural complexity, while diameter-limit cutting often reduced complexity. Silvicultural treatments collectively produced a wide range of residual canopy conditions; however, variability among structural outcomes within individual treatment types or categories was limited relative to the range of possible outcomes from random removals. Most treatments induced shifts in canopy structure outside the spectrum of random removal, suggesting ample space for adapting management to promote forest heterogeneity.

40 years of forest dynamics and tree demography in an intact tropical forest at M’Baïki in central Africa

A vast silvicultural experiment was set up in 1982 nearby the town of M’Baïki in the Central African Republic to monitor the recovery of tropical forests after disturbance. The M’Baïki experiment consists of ten 4-ha Permanent Sample Plots (PSPs) that were assigned to three silvicultural treatments in 1986 according to a random block design. In each plot, all trees with a girth at breast height greater than 30 cm were spatially located, numbered, measured, and determined botanically. Girth, mortality and newly recruited trees, were monitored almost annually over the 1982–2022 period with inventory campaigns for 35 years. The data were earlier used to fit growth and population models, to study the species composition dynamics, and the effect of silvicultural treatments on tree diversity and aboveground biomass. Here, we present new information on the forest stand structure dynamics and tree demography. The data released from this paper cover the three control plots and constitute a major contribution for further studies about the biodiversity of intact tropical forests.

Effect of silvicultural treatments on forest diversity and structure in temperate forests under management in Durango, Mexico

<p>The present study evaluated the effect of silvicultural treatments on the diversity and structure of species in temperate forest ecosystems in the Municipality of Pueblo Nuevo in the State of Durango, Mexico; it was carried out to know if forest use modifies the diversity, mixture of species, spatial distribution, and dimensional differentiation of individuals in these ecosystems. The evaluation was carried out by comparing 10 plots with management history, which were measured before the application of the treatment and five years later. The diversity indices of Shannon, Simpson and Margalef were compared, as well as indices of structure of mixture of species, spatial distribution, and dimensional differentiation. According to the silvicultural treatments applied, the values of the indices do not present significant differences in their evaluations (p> 0.05), which indicates that forest use does not modify the diversity and structure of species of the tree stratum of this plant community.</p>

Silvicultural treatments improve pest and disease conditions of white pine (Pinus strobus) residual trees and regeneration

Managing multiple forest insect pests and diseases is challenging. For example, in eastern white pine (Pinus strobus) stands whereas partial shading and high seedling density is encouraged to reduce damage by white pine blister rust (Cronartium ribicola) and white pine weevil (Pissodes strobi), dense conditions in the understory may increase damage by foliar diseases such as brown spot needle blight (Lecanosticta acicola) and Caliciopsis canker (Caliciopsis pinea). We evaluated the effect of silvicultural treatments, shelterwoods (residual basal area < 18 m2 ha−1), low density thinnings (residual basal area ≤ 14 m2 ha−1), patch cuts (1.2 ha openings), and untreated controls on damage by these insect pest and diseases in residual overstory trees and regeneration. Shelterwoods and low density thinnings provided a good balance of some shading and reduced stem density, which resulted in less weevil damage and foliar disease severity. Crown condition and quality of regeneration was better in all treatments compared to unmanaged controls. Shelterwoods, low density thinnings and patch cuts have the added benefit on increasing seral habitat, resulting in greater songbird diversity.

Long-term dynamics of aboveground carbon stocks in managed loblolly pine plantations in the southeast United States

Intensively managed pine plantations in the southeastern US could not only meet the increasing demand for traditional wood products and biomass for energy, but also play a critical role in meeting US greenhouse gas emission reduction goals through additional carbon (C) sequestration. Adapting forest management to help mitigate climate change requires better understanding of long-term effects of silvicultural treatments on forest production and C sequestration. With two long-term culture-by-density research experiments for loblolly pine plantations across the southern US, we assessed the impacts of site quality, cultural intensity (operational and intensive), and planting density (741, 1483, 2224, 2965, 3706 and 4448 trees ha−1) on dynamics of aboveground net primary production in C (ANPPC), aboveground live tree C stocks (AGC), and cumulative C lost to tree mortality and other litter production (CLC), and total gross C capture (TGC). Cultural intensity significantly affected ANPPC and AGC before age 15 years, and CLC and TGC during the whole study period; while planting density significantly affected ANPPC before age 15 years, CLC after age 6 years, and AGC and TGC over time. Site quality significantly affected AGC at early and late ages, CLC at mid-rotation, and TGC at early ages. After age 20 years, higher quality sites still resulted in higher AGC than lower quality sites, while higher-planting densities might no longer promote aboveground live tree C stock. Intensive management practices that promote growth along with C accumulation in young stands do not necessarily result in higher C stocks in older stands. There exist a maximum C sequestration rate and a maximum C storage in loblolly pine plantations. Continuing carbon capture in the extended rotation or deferred harvest forests is in no way guaranteed to continuously increase carbon stocks. To develop effective climate-smart forest management recommendations, long-term dynamics of carbon capture, release, and storage, especially in managed forest plantations, need more research.

Introduction pages, NBHA-CN 51(2), 2023

The papers published in Notulae Botanicae Horti Agrobotanici Cluj-Napoca, Issue 2, Volume 51, 2023 represent new exciting research in different topics of life science, respectively in plant science, horticulture, agronomy, crop science, and forestry. Among the interesting articles we invite you to find news about: Cloning and analysis of DlERF23 gene in flower induction; Transcriptomic analysis reveals transcription factors involved in vascular bundle development and tissue maturation in ginger rhizomes (Zingiber officinale Roscoe); In vitro direct organogenesis of the medicinal single-mountain local prioritized vulnerable Greek endemic Achillea occulta under different medium variants; Methodological contribution on seed germination and seedling initial growth tests in wild plants; Deciphering the myth of cold tolerance in soybean: An overview of molecular breeding applications; The gall midge Obolodiplosis robiniae Haldemann (Diptera Cecidomyiidae) new invasive alien species in Europa; Effect of silvicultural treatment of individual selection on the horizontal structure of a pine-oak forest in northern Mexico.

Effect of silvicultural treatment of individual selection on the horizontal structure of a pine-oak forest in northern Mexico

In sustainable forest management it is essential to conserve and maintain biodiversity, the floristic composition and the mixture of its species. For this purpose, the objective of this study was to evaluate the effect of the selection silvicultural treatment as a function of time, on the horizontal structure of a Pine-Oak Forest in northern Mexico. Nine sampling points were established to analyze the structure of the Initial Condition of the forest in 2012, the Recruitment of 2022 and the Final Condition of 2022. In addition, the Jaccard similarity coefficient and the Margalef wealth index were estimated. Likewise, Shannon true diversity index, the importance value index and the forest value index were calculated for each species. The analysis of variance with a confidence of 95% was used to evaluate the studied variables, multiple comparisons were made with Duncan's test to group the species in ranges of statistical importance. The results indicated that the forest not presented a change in similarity, richness and diversity of species due to the application of the selection silvicultural treatment, without statistical differences according to the mix and distribution of the species in the forest, this indicates that selective logging does not change the composition of forest species. Regarding the indices of true diversity, value of importance and forest value by species, no significant differences were observed in terms of the application of silvicultural treatment. According to these results, it was possible to identify groups of forest importance and value, where Pinus durangensis Martínez was the most representative species.

Silvicultural Treatments Affect Growth and Foliar Nutrients in a Young Ponderosa Pine Stand

Abstract Foliar nutrient status, diameter, and height growth were investigated for young ponderosa pine (Pinus ponderosa) stands grown under six fertilizer and herbicide treatments (including control) in southeast Washington to diagnose foliar nutrient status and evaluate the effects of silvicultural treatments on growth rates. Two application methods of fertilizer (one “best guess” multi-nutrient fertilizer blend) and herbicide applications (broadcast or spot) were used in the study. Broadcast herbicide application produced higher tree growth responses than spot application. The two broadcast application methods improved diameter increments by 43.3%, whereas the average response of the three spot application methods during the third growing season was only 14.5%. Height growth response for these same two treatments was much less than the diameter response. Fertilizer application in addition to herbicide did not significantly increase tree growth over herbicide alone. Foliar nutrient response to fertilization based on foliar vector analysis was inconsistent, possibly due to nutrient imbalances resulting from the one multi-nutrient blend used in our experiment. Control of grass completion produced a rapid posttreatment early growth trajectory and suggested that stand establishment was successful in this plantation. Our results should also be useful in naturally regenerated young ponderosa pine forests subject to heavy grass competition. Study Implications: Given the increasing need for reforestation in the western United States, results from our study should provide useful information for forest managers. Stand establishment is a critical phase for ponderosa pine stands. Broadcast herbicide application in a recently established plantation produced a rapid early growth trajectory. In this experiment, reducing severe sod grass competition was the most important factor that increased tree growth. Our results may also apply to naturally regenerated ponderosa pine stands. Fertilization with a multi-nutrient fertilizer blend did not significantly increase tree growth as a separate treatment or when combined with herbicide. Foliar nutrient response to fertilization was inconsistent, possibly due to nutrient imbalances resulting from the multi-nutrient fertilizer blend used in our experiment. Fertilization rate and nutrient composition trials are needed to develop effective fertilization treatments in young ponderosa pine stands. Based on our results, fertilizing without vegetation control is not recommended when there is heavy grass competition. The grasses proliferated following only fertilization to the detriment of the trees. For the conditions in our study, we cannot recommend adding fertilizer in addition to the herbicide as a treatment because fertilization did not significantly increase tree growth over herbicide alone. We feel fertilization rate and nutrient composition trials are needed to develop effective fertilization treatments in young ponderosa pine stands. The establishment of ponderosa pine forests is vital for the future timber they may produce and the ecological benefits they provide. We recommend broadcast herbicide as an effective silvicultural treatment to control competing vegetation (from grasses in our experiment) during the stand establishment of ponderosa pine. As demonstrated in our study, the rapid posttreatment early growth trajectory from vegetation control suggests that stand establishment was successful.

Production, tree size inequality and growth dominance in loblolly pine plantations under different silvicultural management regimes

Understanding stand structure and growth relationships and how they are influenced by silvicultural treatments can help us optimize forest management regimes. With two large long-term silvicultural research experiments in loblolly pine plantations, we examined the effects of planting density, silvicultural intensity (sustained competition control and repeated fertilization), and thinning treatments on temporal patterns of stand biomass, biomass growth, tree size inequality, growth dominance, and on stand growth-structure relationships. Results showed that more intensive silvicultural treatments decreased tree size inequality but increased growth dominance, while higher planting densities increased both tree size inequality and growth dominance in unthinned plots. Growth dominance increased from negative to positive with age. For a given silviculture and planting density, tree size inequality became stable after 15 years while growth dominance continued to change over time. Thinning treatments decreased both tree size inequality and growth dominance, and there were no effects of silviculture and planting density in thinned stands. Stand biomass growth was negatively related to tree size inequality and positively related to growth dominance, after accounting for the effects of silvicultural treatment and planting density.

Effects of Forest Management on the Insect Assemblage of Black Cherry (Prunus serotina) in the Allegheny National Forest.

Over the last decade, the Allegheny National Forest (ANF) in the USA has experienced issues with the regeneration of black cherry (Prunus serotina). This study was conducted to investigate the effects of silvicultural treatment on the insect communities that may affect black cherry pollination and regeneration. We conducted a 2-year study to compare the abundance, richness, and diversity of insects in unmanaged, shelterwood seed-tree, and shelterwood clear-cut stands. Using pan traps, we sampled insects at the ground level and in the canopies of flowering mature black cherry trees. The results of this study showed significant increases in the abundance of insects captured in shelterwood seed-tree stands and in species richness and diversity of insects captured in the canopy of black cherry in shelterwood removal stands, indicating that silvicultural treatment affected the insect community significantly. The dominant insect order was Diptera (true flies, 72.91%, n = 12,668), and Anthalia bulbosa (Diptera: Hybotidae) was the dominant species comprising 33% of all insects found in the canopy of flowering black cherry. The findings in this study could help land managers in managing black cherry for its pollination and natural regeneration.

Biomass distribution, allocation and growth efficiency in European beech trees of different ages in pure even-aged stands in northeast France

Abstract Determination of the biomass and biomass increment of trees in managed stands is a pre-requisite for estimating the carbon stocks and fluxes, in order to adapt the forests to new climatic requirements, which impose to maximize the CO2 retained by forests. Tree biomass and biomass increment equations were formerly developed in two young experimental beech stands in the Hesse forest (NE France). To extend such a study to beech stands of different age classes, it was necessary to build biomass and biomass increment equations that could be used for any age, called generalized biomass equations. For that, trees were sampled in plots covering a large age range in Hesse forest, and in each plot several trees were chosen to represent the different social classes. Compatible biomass and biomass increment equations for the different tree compartments and their combination in above and belowground tree parts were developed and fitted, allowing the analysis of the variations of the biomass distribution and allocation with tree age. Stem growth efficiency (stem growth per unit of leaf area) appeared dependent on tree age and tree social status. The biomass and biomass increment equations established for beech allow the estimation of the biomass and carbon stocks and fluxes (NPP) for the even-aged beech stands of the Hesse forest, whatever their age. These equations could also be used to analyze the effects of silvicultural treatments on the biomass and carbon stocks and fluxes of beech stands, using the available stand growth and yield models of beech.

Effects of silvicultural treatments on post-harvesting residual tree mortality

In recent decades, retention forestry has become an increasingly popular management approach. Previous research has demonstrated that persistence of retained live trees (residuals) is higher when they are larger and more densely packed. Beyond density, minimal research has been done on how differing silviculture treatments post-harvest affect the persistence of these residual trees. Here, we use a silviculture experiment, fully replicated within five sites across Ontario, Canada, to examine how changes in silviculture treatments post-harvest affect residual tree mortality. The five sites in this study include three sites harvested using clearcut with seed tree and two sites harvested using shelterwood systems. Each site included unharvested control plots and a gradient of four silviculture treatments, but harvest intensity did not change within site. We considered mortality to include trees that died post-harvest and either remained standing or blew down. Overall, we found that probability of residual mortality was highly dependent on hierarchical interactions between linked-press (i.e., climate, edaphic conditions, and silvicultural system) and compounded-pulse (i.e., post-harvest silviculture treatments) disturbances. Based on outputs from a structural equation model, press disturbances affected residual tree mortality more than post-harvest pulse disturbances. Post-harvest pulse disturbances increased residual mortality probabilities in seed tree clearcuts but not shelterwoods. However, in seed tree clearcuts, moderate pulse disturbances had similar effects on residual mortality relative to the least intense pulse disturbances. In summary, forest managers can implement moderate intensity pulse disturbances after harvesting without increasing residual tree mortality relative to untreated areas. However, the highest intensities of post-harvest pulse disturbances did not result in complete loss of residuals and, depending on management objectives, the increased loss in residuals and associated loss of ecosystem services may be offset by benefits of higher yield of desired tree species.

Mid-Term Effects of Forest Thinning on N Mineralization in a Semi-Arid Aleppo Pine Forest

In order to assess the sustainability of silvicultural treatments in semiarid forests, it is necessary to know how they affect the nutrient dynamics in the forest. The objective of this paper is to study the effects of silvicultural treatments on the net N mineralization and the available mineral N content in the soil after 13 years following forest clearings. The treatments were carried out following a randomized block design, with four treatments and two blocks. The distance between the two blocks was less than 3 km; they were located in Chelva (CH) and Tuéjar (TU) in Valencia, Spain. Within each block, four experimental clearing treatments were carried out in 1998: T0 control; and T60, T75 and T100 where 60%, 75% and 100 of basal area was eliminated, respectively. Nitrogen dynamics were measured using the resin tube technique, with disturbed samples due to the high stoniness of the plots. Thirteen years after the experimental clearings, T100, T75 and T60 treatments showed a twofold increase in the net mineralization and nitrification rates with respect to T0 in both blocks (TU and CH). Within the plots, the highest mineralization was found in sites with no plant cover followed by those covered by undergrowth. These results can be explained in terms of the different litterfall qualities, which in turn are the result of the proportion of material originating from Pinus halepensis Mill. vs. more decomposable undergrowth residues.

Genetic Variation and the Effect of Herbicide and Fertilization Treatments on Wood Quality Traits in Loblolly Pine

Abstract The effect of silvicultural treatments (herbicide, fertilization, herbicide + fertilization) and the interactions with genetic effects were investigated for wood quality traits in a 16-year-old loblolly pine (Pinus taeda L.) genetic test established in southwest Georgia, USA. Fertilizer and herbicide treatment combinations were applied multiple times to main plots containing 25 open-pollinated families as sub plots. Significant differences among treatments were found for all traits. Squared acoustic velocity, used as a surrogate for wood stiffness, was higher in herbicide-only plots compared with other treatments. Wood density was considerably lower in fertilization plots. A large proportion of variance observed for wood quality traits was explained by additive genetic effects, with individual-tree heritabilities ranging from 0.78 (ring 7–16 section wood density) to 0.28 (ring 2–6 section wood density). Corresponding family-mean heritability values were well over 0.86. Genotype-by-treatment interactions were nonsignificant for all traits, indicating no need to match families to silvicultural treatments. Wood quality traits had weak genetic correlations with growth and stem quality traits (stem slenderness, sweep, and branch angle) with a range of −0.33 to 0.43, suggesting that recurrent selection on growth or stem quality traits would not adversely affect wood quality in loblolly pine.

EFFECT OF PRE-SOWING TREATMENT ON THE SEED EMERGENCE OF DIOSPYROS MESPILIFORMIS

This study was carried out at Kebbi State University of Science and Technology, Aliero, Kebbi State, to determine the effect of silvicultural treatments on the germination and early growth of Diospyros mespiliformis. The study was carried out in the Forestry Laboratory of the Faculty of Agriculture. The effectiveness of nine (9) different presowingtreatments were assessed, control inclusive. Treatment 1 (TRT1) seeds were soaked in tap water for 48 hours, Treatment 2 (TRT2) seeds were mechanically scarified opposite to microphyle, treatments 3, 4, and 5 (TRT3, TRT4, TRT5) seeds were immersed in H2SO4 for 5, 10 and 15 minutes respectively, treatments 6, 7 and 8 (TRT6, TRT7 and TRT8) seeds were soaked in hot water (100oC) for 5, 10 and 15 minutes respectively and untreated seeds (CNTRL). Completely Randomized Design with three (3) replications was used. The data obtained were analyzed using one-way Analysis of Variance (ANOVA).Seeds of D. mespiliformis subjected to TRT1, TRT2, TRT3, TRT6, TRT7 and TRT8 recorded with highest FGP (100%) and was found to differ significantly (P<0.05) with other treatment and CNTRL recorded the least FGP (83.33%).Thus, TRT 3 was shown to be the best asit’s recorded with 100% FGP, MGT value of 7.53, highest GRI (14.57), lower FDG (6), highest GE (11.57), and maximum GI value (913.33).Based on the result, pre-treatment of D. mespiliformis seeds with sulphuric acid is recommended for the mass production and uniform germination.

Use of Multi-Temporal LiDAR to Quantify Fertilization Effects on Stand Volume and Biomass in Late-Rotation Coastal Douglas-Fir Forests

Forest fertilization is common in coastal British Columbia as a means to increase wood production and potentially enhance carbon sequestration. Generally, the effects of fertilization are determined by measuring sample plots pre- and post-treatment, resulting in fertilization effects being determined for a limited portion of the treatment area. Applications of remote sensing-based enhanced forest inventories have allowed for estimations to expand to the wider forested area. However, these applications have not focused on monitoring the effects of silvicultural treatments. The objective of this research was to examine if a multi-temporal application of the LiDAR area-based method can be used to detect the fertilization effects on volume, biomass, and height in a second-growth Douglas-fir (Pseudotsuga menziesii) stand. The study area on Vancouver Island was fertilized in January 2007, and sample plots were established in 2011. LiDAR acquisitions were made in 2004, prior to fertilization, and in 2008, 2011, and 2016, covering both treated and untreated areas. A total of 29 paired LiDAR blocks, comprised of four 20 m resolution raster cells, were selected on either side of the fertilization boundary for analysis of the effects across several different stand types differing in the percentage of Douglas-fir, site index, and age. Random forest (RF) plot-level models were developed to estimate total stem volume and total stem biomass for each year of LiDAR acquisition using an area-based approach. Plot level results showed an increase in stem volume by 13% fertilized over control from 2005 to 2011, which was similar to a 14% increase in above-ground carbon stocks estimated using a tree-ring stand reconstruction approach. Plot-level RF models showed R2 values of 0.86 (volume) and 0.92 (biomass) with relative cross-validated root mean square errors of 12.5% (volume) and 11.9% (biomass). For both the sample plots and LiDAR blocks, statistical results indicated no significant differences in volume or biomass between treatments. However, significant differences in height increments were detected between treatments in LiDAR blocks. The results from this research highlight the promising potential for the use of enhanced forest inventory methods to rapidly expand the assessment of treatment effects beyond sample plots to the stand, block, or landscape level.

A multi-criteria analysis of forest restoration strategies to improve the ecosystem services supply: an application in Central Italy

A multi-criteria analysis can be an interesting tool to assess the effects of silvicultural treatments on ecosystem services supply. In the degraded forests, thinning has a positive effect on the provision of ecosystem services such as timber and bioenergy production, climate change mitigation, and recreational attractiveness. The Millennium Ecosystem Assessment highlights the importance of the ecosystem services for human well-being and for maintaining conditions for life on Earth. Silvicultural treatments can improve the provision of ecosystem services to increase local communities’ well-being. The aim of this study is to understand the effects of two-forest restoration practices (selective thinning and thinning from below) on three ecosystem services (wood production, climate change mitigation, and recreational opportunities) in an Italian case study. A multi-criteria decision analysis (MCDA) was performed to compare the effects of three forest restoration scenarios (baseline, selective thinning, thinning from below) on ecosystem services. Wood production was estimated considering the local market prices and the wood volumes harvested, while climate change mitigation was quantified through the C-stock and C-sequestration changes in carbon pools due to the silvicultural treatments. The recreational activities were assessed through a questionnaire survey. A sample of 200 visitors was interviewed face-to-face to estimate the impact of thinning on recreational activities. The results of the MCDA show that the selective thinning scenario is the optimal forest restoration practice to increase the recreational attractiveness and the wood production in the study area. The results concerning the effects of the silvicultural treatments on ecosystem services supply are an important tool to support decision makers.

Effect of Thinning on Forest Scenic Beauty in a Black Pine Forest in Central Italy

Forest management practices determine changes in stand characteristics and consequently influence public perception of forest scenic beauty visually appreciated by visitors. To understand the relationship between forest management practices and public perception, the present study evaluated the effects of thinning on the forest scenic beauty analyzing visitors’ preferences towards images of forest managed in different ways. The investigation was implemented in a black pine (Pinus nigra spp.) forest located in Central Italy, where a designed thinning experiment was conducted during the winter of 2016. Silvicultural interventions were based on three options: traditional thinning (medium-intensity thinning from below), selective thinning, and absence of intervention (control). Then, through the face-to-face administration of a questionnaire to a sample of 200 visitors, visitors’ aesthetic preferences for stands’ characteristics affected by management interventions were assessed. The survey also investigated the perception of the effect of silvicultural treatments on the scenic beauty using pairwise comparison method. Results evidence a strong relation between scenic beauty and forest attributes. In particular, the results show that visitors prefer mixed forest with varying tree heights and layers, and consequently a high and variable quantity of light reaching the soil. Results also show that visitors prefer managed forests, and both kinds of thinning have a positive effect on the scenic beauty.

A meta-analysis of the effects of tree retention on shrubland birds

The effects of forest management on native fauna are of key interest to managers and conservationists. Individual studies have expanded our knowledge of management impacts, but meta-analyses of multiple studies are needed to summarize and integrate findings into a more generalizable form. Most meta-analyses on the effects of tree harvesting have focused on mature forest taxa because of concerns for these species; however, early-successional specialists, such as shrubland birds in the eastern United States, are also of key conservation concern. Using data from 34 studies that examined the effects of silvicultural treatments on bird communities, we conducted a meta-analysis to determine the effects of tree retention on a suite of bird species reported to be associated with shrubland habitats within the northeastern United States. Of 21 putative shrubland bird species for which we had sufficient sample sizes for analyses, most (62%) exhibited monotonic declines of density with increasing tree retention, defined as percent basal area or canopy cover retained. Five other species (24%) exhibited quadratic relationships with tree retention. Finally, three additional species (14%) considered to be shrubland birds did not exhibit significant relationships with tree retention. We also calculated density estimates of shrubland birds in three categorical classifications of basal area retention corresponding to common management regimes: regeneration harvests with little retention (clearcut and seed-tree methods), regeneration harvests with moderate retention (shelterwoods), and high retention management regimes (commercial thinning, selection methods, no management). Many of the shrubland species had high densities in clearcuts as well as in stands with low levels (5–25%) of mature tree retention, and some species had equally high densities in stands with moderate tree retention (30–70%), supporting the use of retention forestry approaches, which can provide other benefits associated with mature trees. Overall, our findings provide managers and conservationists with robust, quantitative relationships of shrubland birds with tree retention. Managers can use these quantitative relationships for more detailed planning and evaluation of silvicultural projects, more so than what was feasible using previous findings of shrubland bird responses to discrete silvicultural treatments from disparate studies.

Silviculture and fire effects on understorey flowering in jarrah forest

ABSTRACT Long-term forest monitoring undertaken by Forestcheck since 2001 has examined the effects of silvicultural treatment on floral diversity and assemblage composition in the jarrah forest of southwest Western Australia. Both prescribed burns and wildfires have overlain the network of Forestcheck monitoring sites, providing the opportunity to examine fire and silviculture interactions in natural experiments and allowing experimental control of time-since-fire effects on the flora. We report here two opportunistic experiments. First, the early effects of prescribed burns in spring on the flowering of the vascular flora were compared with closely paired sites that were long unburnt. Second, the early effects of a wildfire in summer on the flowering of the vascular flora were compared between silvicultural treatments. Flowering richness tended to be less on burnt grids in the non-peak period in the first two years after fire in one experiment, but there were no differential effects of silviculture on flowering assemblages arising from interaction with wildfires. Flowering assemblages varied from year to year and the extent to which they varied differed between locations but not as a result of silvicultural treatments. We conclude that no special management with respect to plant flowering is required to remedy outcomes of interaction between wildfire and silvicultural treatments. Further information is needed to understand the long-term implications of variability in flowering assemblages and how it affects the reproductive viability of understorey species and their interactions with pollinator networks in the face of a changing climate.