Desirable Tree Species Research Articles

Status of Private Plantation and their Management in Siraha distict of Nepal: A case study

The research work was conducted to find out the status of private forests with the major species planted and managed in the Terai. Additionally, the present status of private forests and the scenarios of selling procedure, and the silviculture practices that are applied, were studied and form a basis on which further research could be carried out. The research is based on a descriptive and field survey. The serious issue recognized that upset the private forest improvement was the absence of land accessibility, lack of seedling of the desired tree species, absence of specialized information, absence of fitting business sector and market cost, and inappropriate timber utilization. The discoveries additionally incorporate that an uncommonly moderate pace of private forest registration, long and multi-stage forms for getting, collecting and transportation licenses and authority bans on significant commercial species, among others, are seen as the variables that most ruin the private forest proprietors and tree producers interest and their advantages and obligations concerning the association and utilization of their private forest assets. It is concluded that a disentangled allowing process would elevate and assist private forestry.

Competitiveness of Rosa multiflora Thunb. in varying plant communities and light regimes compared with co-occurring native species

Multiflora rose (Rosa multiflora Thunb.) is a non-native invasive shrub of central lower Michigan that is broadly distributed throughout much of the non-mountainous U.S. Like many non-native invasive species, multiflora rose (MR) colonizes a variety of habitats where it competes with and replaces native plant species. The goal of this research was to compare the light and water use efficiency of MR with co-occurring native woody plants in mature forests with minimal light penetration to the forest floor, young forests with substantial light penetration, and edge or meadow habitats with full sunlight exposure. Photosynthesis rate, transpiration rate, and leaf chlorophyll content were measured for MR and two co-occurring native woody plants. Black cherry and Virginia creeper are native woody plants found to co-occur with MR in every replicate location of all three habitats assessed. MR was significantly more light use efficient than Black cherry at light intensities greater than 750 W/m2 and exhibited a much broader light use efficiency advantage over Virginia creeper at light intensities greater than 100 W/m2. These results indicate land managers should prioritize surveillance of high value landscapes with high levels of incident light when there is little or no MR infestation, choosing first to remove MR from quality forest habitats with less light because mitigation efforts in these areas are more likely to be successful. Removal or death of overstory plants will increase the risk of encroachment by MR which could also inhibit juvenile recruitment by desired tree and forest floor ephemeral species. Encouraging the growth of overstory plants to shade MR in forests to minimize the amount of light reaching it will reduce MR competitiveness even after MR has been established.

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.

Timber harvesting on fragile ground and impacts of uncertainties in the operational costs

ABSTRACT Forested wetlands with high water tables are sensitive to disruption from harvesting yet support commercially desired tree species like northern white-cedar. Winter harvest was conducted in Maine, USA, to compare operational costs and productivity of cut-to-length harvesting in cedar (fragile soil) and non-cedar stands (mixedwood, sturdy soil), evaluate uncertainties in harvesting costs and influential factors, and forecast time for post-harvest recovery to pre-harvest volumes. Operational costs were calculated using detailed time and motion studies. Operational costs for the cedar stands were higher than non-cedar. Regression models were developed for harvesters, forwarders, and self-loading trucks; number of logs per cycle was a common factor. Sensitivity analysis showed the dependence of operational costs on labor and fuel costs. Forest Vegetation Simulator projections were used to assess harvest sustainability and suggested the time required to regrow harvested merchantable volume is comparable to cutting cycles recommended for similar treatments in the region. Predicted growth rates exceed those reported regionally on similar sites, suggesting additional study of post-harvest response is warranted. Results highlight site constraints on both operational and stand productivity in lowlands and will be useful for timber harvesting decision-making and forest management planning if combined with assessment of residual stand growth response.

Effects of Mechanical Site Preparation, Planting Stock, and Planting Aids on the Survival and Growth of American Sycamore in a Marginal Old Field Riparian Restoration

Survival and growth of planted tree species are common indices used to evaluate success of wetland restoration efforts used to compensate for wetland losses. Restoration efforts on marginal agricultural lands have typically resulted in less than satisfactory survival and growth of desired tree species. In an attempt to determine the effects of bottomland hardwood silvicultural methods on the survival and growth of pioneer tree species, this study evaluated combinations of five mechanical site-preparation techniques (mound, bed, rip, disk, pit), four levels of planting stock (gallon, tubeling, bare root, and direct seed), and three planting aids (mat, tube, none) on the four-year survival and growth of American sycamore planted in an old field riparian area in the Piedmont of Virginia. After four growing seasons, results indicated that mounding mechanical site preparation combined with gallon (3.8 L) planting stock provided the most positive influences on mean survival (100%), height (4.72 m), and groundline diameter (9.52 cm), and resulted in the greatest aboveground dry biomass accumulation (5.44 Mg/ha/year). These treatments may be economically viable for restoration and mitigations efforts, and could offer other economic alternatives such as short-rotation woody crops, which might make restoration efforts in marginal old field areas more attractive to private landowners.

Seasonality of Biennial Burning Has No Adverse Effects on Mature Longleaf Pine Survival or Productivity

Emulating natural disturbance has become an increasingly important restoration strategy. In the fire-maintained woodlands of the southeastern United States, contemporary restoration efforts have focused on approximating the historical fire regime by burning at short intervals. Due to concerns over escape and damage to mature trees, most prescribed burning has occurred in the dormant season, which is inconsistent with the historical prevalence of lightning-initiated fire in the region. This discordance between contemporary prescribed burning and what is thought to be the historical fire regime has led some to question whether dormant season burning should remain the most common management practice; however, little is known about the long-term effects of repeated growing season burning on the health and productivity of desirable tree species. To address this question, we report on a long-term experiment comparing the effects of seasonal biennial burning (winter, spring, and summer) and no burning on the final survival status, height, diameter, and volume growth of 892 mature longleaf pine (Pinus palustris) over 23 years in three mature even-aged stands in southern Alabama, United States. Overall, longleaf pine survival across all treatments averaged 81 ± 2% [s.e]. Among seasonal burn treatments, survival was highest in the spring burns (82 ± 4%) but did not vary significantly from any other treatment (summer – 79 ± 4%, winter – 81 ± 4%, unburned – 84 ± 4%). However, survival was statistically influenced by initial diameter at breast height, as survival of trees in the largest size class (30 cm) was 40% higher than trees in the smallest size class (5 cm). Productivity of longleaf pine was not significantly different among treatment averages in terms of volume (38.9–44.1 ± 6.0 m3 ha–1), diameter (6.0–6.7 ± 0.3 cm), and height (2.5–3.4 ± 0.4 m) growth. Collectively, our results demonstrate that burning outside the dormant season will have little impact on mature longleaf pine survival and growth. This finding has important implications for the maintenance of restored southeastern woodlands, as interest in burning outside the dormant season continues to grow.

A demographic equilibrium approach to stocking control in mixed, multiaged stands in Bialowieża Forest, northeast Poland

Manifold benefits and advantages of mixed tree stands have been known for many decades. However, while developing and maintaining multiaged and mixed-species forests with complex stand structures has often been advocated and has recently become a worldwide priority, it is not a simple task. One important reason for this is a lack of appropriate methods for controlling long-term development of such stands. Here, we present a possible solution for this problem by applying the demographic equilibrium approach to guide stocking and structure regulation in mixed stands. We tested the practical usefulness of this approach using permanent-plot inventories from 2002, 2011 and 2018, in mixed tree stands in the Experimental Sustainability Unit (ESU) Browsk 28C, in the managed part of Białowieża Forest (NE Poland). For our analysis, ESU Browsk 28C (about 30 ha) was treated as a silvicultural planning unit. First, on the basis of target stand types defined in Polish Silvicultural Guidelines (2012) and forest sites occurring at the study site, desirable tree species composition was determined. Eleven tree species of varying life histories and ecological attributes were included: aspen, birch, alder, pine, oak, maple, ash, elm, spruce, lime, and hornbeam. In the second step equilibrium diameter distributions were constructed for each species, taking into account species-specific growth and mortality rates, as well as targeted proportional representation. Next, theoretical species-specific equilibrium diameter distributions were visually and quantitatively compared with empirical distributions from permanent sample plots. Finally, departures of empirical from theoretical distributions served as a basis for silvicultural recommendations and prescriptions. We prioritized silvicultural measures (such as patch cuts opening larger gaps in forest canopy, proper site treatment, planting, protection against browsing by large herbivores), promoting compositionally diverse forest reproduction and recruitment as essential to long-term maintenance of demographic sustainability in mixed forest stands. We conclude that the demographic equilibrium approach is particularly valuable for creating and maintaining complex forest structures in multi-species stands.

Farmer-led approaches to increasing tree diversity in fields and farmed landscapes in Ethiopia

Increasing tree cover and managing trees better on farms in Ethiopia supports livelihoods and the environment but most tree-planting schemes promote only a few species. This research aimed to understand farmers’ tree planting priorities in Oromia, Ethiopia and address challenges involved in meeting them. Tree species and planting niches were elicited through focus group discussions. Participatory trials compared 17 tree species across seven on-farm planting niches and seedling survival and growth patterns were evaluated. Farmers suggested a high diversity of tree species suitable for each niche with fruit species mainly selected for homesteads. The diversity of desired tree species is much higher than that typically available in nurseries or promoted by tree planting projects. Meeting planting demands was difficult because the existing seedling supply does not support diversity. Evaluation of tree survival showed striking differences among species, farms, agroecologies and planting niches. There was high variation in seedling survival amongst the tree species planted on 1893 farm/planting niche locations, indicating impact of local level risk factors attributable to management, biotic and abiotic causes. Growth differences of the six shared species common to both agroecologies across different niches, showed that the effects of species and niche were significant on growth. A farmer-led approach to increasing tree cover that couples understanding of species and planting niche preferences with appropriate seedling supply and management is proposed as a means to increase the diversity of trees in farmed landscapes.

Performance of Pinus patula in Areas Invaded by Acacia mearnsii in Sao Hill Forest Plantation, Southern Tanzania

ABSTRACT Problems associated with the invasiveness of exotic tree species such as Acacia mearnsii have increased recently causing vast damage in environment and economy worldwide. Sao Hill Forest Plantation (SHFP) in southern Tanzania which is the potential plantation in East Africa is under Acacia mearnsii invasion which threatens the productivity of the planted species, Pinus patula. This study aimed to gather information on the performance of Pinus patula by comparing areas invaded by Acacia mearnsii with the non-invaded areas in SHFP. The study used a combination of stratified and random sampling techniques to select sample plantation blocks and plots allocation, respectively. Data collected included survival, height, and diameter of Pinus patula in both invaded and non-invaded areas as well as Acacia mearnsii stem counts in invaded areas. The mean basal area, density, and volume of Pinus patula were subjected to paired sample T-test and relationship between the density of Acacia mearnsii and survival of Pinus patula were established by Pearson’s correlation analysis in R software version 3.5.2. Results showed that survival of Pinus patula was decreasing as the density of Acacia mearnsii increased. Also, there was a significant difference in density, basal area and volume of Pinus patula between invaded and non-invaded areas with higher performance being in non-invaded areas. Results suggest that Acacia mearnsii has a negative effect on the performance of Pinus patula in both its growth and survival. This study has generated the information for which among others will help to formulate policies and strategies that will contribute to the effective and sustainable management of forest plantations that should incorporate invasive control measures to avoid the negative performance of desirable tree species.

Evaluating the impacts of white-tailed deer (Odocoileus virginianus) browsing on vegetation in fenced and unfenced timber harvests

Ensuring the recruitment of desired tree species is a primary goal when considering successful regeneration of timber harvests. Deer populations that are overabundant relative to forage availability within their local landscapes pose a considerable challenge to successful forest regeneration. We evaluated the short-term (<10 years) impact of white-tailed deer browsing on woody structure and composition in northcentral Pennsylvania. Specifically, we compared woody plant species density, height, and cover within 10 pairs of fenced and unfenced regenerating timber harvests. Percent of browsed stems was higher in unfenced harvests for red maple (Acer rubrum), oaks (Quercus spp.), Rubus spp., sassafras (Sassafras albidum), and witch hazel (Hamamelis virginiana). Stem density did not differ between fenced and unfenced harvests for any species except Rubus spp., which was greater in the former. However, height of serviceberry (Amalanchier spp.), sassafras, northern red oak (Quercus rubra), Rubus spp., and red maple was taller in fenced harvests. Both vertical and horizontal vegetation density were greater in fenced harvests, suggesting a more structurally complex understory in fenced harvests. Rubus spp. and tall (>1.5 m) sapling cover were greater in fenced harvests, while unfenced harvests had greater forb, fern, and blueberry/huckleberry (Vaccinium spp./Gaylussacia spp.) cover. Our results suggest that browsing by deer in the years initially (<10 years) following timber harvest may not immediately impact woody species density, but can considerably reduce seedling height, overall horizontal and vertical structure, and composition of vegetation strata. Reduced sapling height and greater prevalence of blueberry/huckleberry, forbs, and ferns in unfenced harvests threaten the successful recruitment of desired species into the future overstory. Our results from large, operational-scale timber harvests combined with those from previous small-scale studies stress the potential value of deer exclusion fencing to achieve successful forest regeneration. Future research should examine the timing of fence removal to achieve forest regeneration success, while also providing deer access to available foraging opportunities during the later portion of stand initiation.

Adoption of Agro-Forestry among Farmers in Onigambari area of Oyo State, Nigeria

This study was carried out in the Onigambari area of Oyo state to determine the choice of farmers to practice Ago-forestry in the area. The χ2 test result revealed that the educational level of the respondents correlated highly with the respondents major occupation (p&lt;0.01). χ2 test shows that there was significant relationship (p&lt;0.01) between the respondents’ level of education and awareness of agroforestry systems. This shows that farmers with a better educational background can accept agro forestry easily than those will lower education. Farmers’ awareness of Agroforestry systems, willingness to plant trees, purpose of planting trees and desired tree species were evaluated. It was observed that 74% of the respondents are not willing to practice agroforestry while 24% shows interest. 64% confirmed they are aware of the practice while 32% had never heard of such practice. The t-test result shows a significant difference with respect to the willingness of the respondents to practice agroforestry. Of those that areaware, 38% practice agroforestry for the purpose of fuel wood, 36% as source of income while only 2% practice for the purpose of wind breaking. Eucalyptus calmuldulensis, Magnifera indica, Gmelina aboreal are some of the tress used for this practice in the study area. Lack of seed and scarcity of land were identified as limiting factors that prevent farmers from practicing agroforestry. In summary it was observed that the respondent’s level of education correlated significantly to the level of education, also the level of education determines respondent’s willingness to practice agroforestry. It is recommended that Seeds, Seedlings and land be made available to encourage the practice among farmers. Extension workers are encouraged to engage farmers more on the benefits of agroforestry.&#x0D; Keyword: Farmers, Agroforestry, Climate change, Land degradation, Natural Fallow

Understory diversity and composition after planting of teak and mahogany in Yogyakarta, Indonesia

ABSTRACT Forest rehabilitation is when a desired tree species is planted in degraded forests or lands. Rehabilitation by planting a single tree species is a common way to restore exploited forests to maintain ecological processes. We compared woody and herbaceous understory vegetation between forests rehabilitated by mahogany (N = 12) or teak (N = 12) planted from 1941 until 2003 in Yogyakarta, Indonesia. Understory vegetation of these areas was compared with that of three native forests. Species richness, species diversity, density of plants and proportion of native plants did not differ between the rehabilitated areas and the native forest. Recently rehabilitated areas were different from the native forests while 41–74 yr after rehabilitation, characteristics of understory vegetation approached those of native forest. We described species composition using ordination, and found it to differ between areas rehabilitated with teak and with mahogany and, particularly, between the rehabilitated areas and the native forests. Time since rehabilitation and tree species planted were important for the species composition of understory vegetation. We conclude that the selection of species for rehabilitation and letting rehabilitated areas mature are important for understory development and species diversity.

Silvopasture in the Caatinga biome of Brazil: A review of its ecology, management, and development opportunities

Aim of study: Silvopastoral system (SPS) involving numerous indigenous trees and shrubs is a traditional land-use system in the Caatinga, but it has little been studied scientifically. Given the importance of SPS as a sustainable land-use strategy in the drylands, this paper examines the attributes of the Caatinga SPS and their relevance to other arid and semiarid regions.Area of study: Caatinga biome, with an area of 0.9 million km2 and a population of 25 million, a unique dryland ecosystem of Brazil.Materials and methods: The paper reviewed the literature on the main characteristics of SPS management of the Caatinga biome and the global perspectives of silvopastoral land-management in semiarid regions.Main results: Guidelines for sustainable SPS management of the Caatinga include maintaining up to 400 trees/ha (40% tree cover) and allowing at least 40% of the available forage to dry up to provide mulch for soil protection. Opportunities for improving the low carrying capacity of the Caatinga are thinning, coppicing, and enrichment planting with desirable tree and understory species. Establishment of fodder banks, promotion of non-conventional feed sources such as cactus, and introduction of grazing animals to orchards and plantations are some other promising interventions.Research highlights: The review highlights the importance of initiating new studies on Caatinga SPS, focusing on the role and potential of various native species and the ecosystem services they provide, in conjunction with relevant social, economic, and policy aspects to better exploit the benefits of the system and facilitate its wider adoption.

Building Resistance and Resilience: Regeneration Should Not be Left to Chance

Contemporary forest planning has tasked managers with developing goals associated with resistance and resilience. In practice, silviculturists use forest structure and tree species composition to characterize goals and desired future conditions, write prescriptions, and monitor outcomes associated with resistance and resilience. Although rarely discussed in the exploding literature relating to forest resistance and resilience, silvicultural regeneration methods are important and underutilized tools to meet these goals. We propose alternative silvicultural systems for building resistance and resilience to two common large-scale bark beetle disturbance agents in the Intermountain West, United States: mountain pine beetle (Dendroctonus ponderosae Hopkins) and spruce beetle (Dendroctonus rufipennis Kirby). Shelterwood, and shelterwood-with-reserves, silvicultural systems provide the desirable facilitative characteristics of a mature overstory on maintaining advance reproduction and the establishment of new cohorts of desirable tree species. These also allow the timely regeneration of large treatment areas necessary to rapidly promote desired future conditions in the face of inevitable disturbance. When implemented proactively, regeneration treatments allow silviculturists to take advantage of currently existing vegetation for the creation of age class and tree species diversity. In general, these examples illustrate the need for proactive planning for regeneration in response to any disturbance where desired future conditions include particular species. Furthermore, we argue that timely silvicultural interventions that focus on regenerating trees may be a key factor in achieving goals relating to resilience to specific disturbance types. Waiting until after the disturbance has occurred could result in the lost opportunity to establish desired species composition or stand structure—and may well result in a considerable restoration challenge.

Influence of browsing damage and overstory cover on regeneration of American beech and sugar maple nine years following understory herbicide release in central Maine

Northern hardwood stands, notably those with American beech (Fagus grandifolia Ehrh), sugar maple (Acer saccharum Marsh.), and yellow birch (Betula alleghaniensis Britton), are abundant across the forested landscapes of northeastern USA and southeastern Canada. Recent studies have reported an increasing dominance of American beech in the understory and midstory of these forests. Beech is a commercially less desirable tree species due to its association with beech-bark disease, and because it commonly interferes with the regeneration of other more desirable tree species. We examined hardwood regeneration characteristics nine years after application of a 3 × 4 factorial combination of glyphosate herbicide (0.56, 1.12, and 1.68 kg ha−1) and surfactant concentrations (0.0, 0.25, 0.5, and 1.0% v v−1) to release sugar maple regeneration from beech-dominated understories using three stands that received shelterwood seed cutting in central Maine. Measurements nine years after treatment showed that glyphosate rate increased both absolute (AD) and relative density (RD) of sugar maple regeneration, but not its height (HT). In contrast, beech AD, RD, and HT were all significantly reduced with increasing glyphosate rate. Post-release browsing by ungulates and a high residual overstory basal area resulted in reduced sugar maple HT. Our results indicated that glyphosate herbicide applied in stands that have been recently shelterwood seed cut can significantly increase the abundance of sugar maple regeneration. However, subsequent browsing damage combined with the negative influence of the residual overstory cover can limit the longer-term benefit of understory herbicide treatments. Subsequent removal of the overstory and browsing-control measures may be needed to promote sugar maple regeneration over beech in similar northern hardwood stands.

Prescribed Burning and Erosion Potential in Mixed Hardwood Forests of Southern Illinois

Prescribed fire has several benefits for managing forest ecosystems including reduction of fuel loading and invasive species and enhanced regeneration of desirable tree species. Along with these benefits there are some limitations like nutrient and sediment loss which have not been studied extensively in mixed hardwood forests. The objective of our research was to quantify the amount of sediment movement occurring on a watershed scale due to prescribed fire in a southern Illinois mixed hardwood ecosystem. The research site was located at Trail of Tears State Forest in western Union county, IL, USA and included five watershed pairs. One watershed in each pair was randomly assigned the prescribed burn treatment and the other remained as control (i.e., unburned). The prescribed burn treatment significantly reduced the litter depth with 12.6%–31.5% litter remaining in the prescribed burn treatment watersheds. When data were combined across all watersheds, no significant differences were obtained between burn treatment and control watershed for total suspended solids and sediment concentrations or loads. The annual sediment losses varied from 1.41 to 90.54 kg·ha−1·year−1 in the four prescribed burn watersheds and 0.81 to 2.54 kg·ha−1·year−1 in the four control watersheds. Prescribed burn watershed 7 showed an average soil sediment loss of 4.2 mm, whereas control watershed 8 showed an average accumulation of sediments (9.9 mm), possibly due to steeper slopes. Prescribed burning did not cause a significant increase in soil erosion and sediment loss and can be considered acceptable in managing mixed hardwood forests of Ozark uplands and the Shawnee Hills physiographic regions of southern Illinois.

Natural Regeneration in a Multi-Layered Pinus sylvestris-Picea abies Forest after Target Diameter Harvest and Soil Scarification

Forest management in Sweden can be characterized by even-aged silviculture heavily relying on three established harvest regimes: clearcutting, the seed-tree method, and the shelterwood system. Less intense, small-scale retention harvest systems such as single tree and group selection harvest are rarely used. In addition, natural regeneration dynamics without enrichment planting have barely been studied. Consequently, this study examined natural regeneration establishment in a multi-layered Pinus sylvestris-Picea abies forest stand in southwest Sweden after target diameter harvesting and soil scarification. The creation of forest canopy gaps had a positive effect on total seedling density five years after harvest, mainly due to a significantly higher number of Betula pendula individuals. Seedling density of more desirable tree species suitable for continuous cover forestry such as Fagus sylvatica, Quercus petraea and Picea abies also increased substantially in gaps when compared to pre-harvest conditions or the unharvested plots. In contrast, soil scarification did not increase the number of seedlings of desired tree species due to a significant decrease in Picea abies abundance. Soil moisture and gap size significantly improved Betula pendula seedling establishment while a larger number of Quercus petraea seedlings were observed in Vaccinium myrtillus patches. We conclude that canopy gaps are beneficial under the encountered stand conditions to initiate forest regeneration, and that soil scarification without the timely occurrence of a mast year of desired tree species is not effective in the type of forest studied.

Interactive effects of a non‐native invasive grass Microstegium vimineum and herbivore exclusion on experimental tree regeneration under differing forest management

Summary Invasive plants, herbivores and site management history can play crucial roles in determining plant community composition. The net effects of invasive species on plant communities are well known, but we have a poor understanding of the relative contributions of direct competitive effects of invasive species and their interactions with herbivores and management practices. Understanding interactions among plant invasions, herbivores and management history is critical for predicting and managing long‐term ecological effects of invasions on native communities. We investigated the effects of the invasive annual grass Microstegium vimineum, vertebrate herbivory, site management history and their interactions on seedling performance of five native tree species in six forest sites. Half of the sites had been subjected to recent timber harvesting, and half had not been managed for timber for at least 20 years. We evaluated tree seedling survival and biomass after two growing seasons in blocked split‐plots where the invasive grass was present or experimentally removed and where vertebrate herbivores were excluded by fencing or allowed onto the plots. Removal of the invasive grass and herbivore exclosures both had positive effects on seedling survival. Survival of all species was significantly increased by removal or by the interaction of removal with exclosure or timber harvest history. There was a significant interaction between exclosure and removal on seedling biomass where seedlings were larger in exclosure treatments with the invasive removed but smaller in exclosure treatments when the invader was present. Mean seedling biomass was 79·6% greater in harvested sites than in non‐harvested sites. The significant positive effects of removal and recent timber harvest on the biomass of two Quercus species suggest strong impacts of invasion and management history on this important genus. Synthesis and applications. An invasive grass directly inhibited tree seedling performance but effects depended on herbivore exclusion treatment, timber harvest history and tree species. Our results suggest that forest management strategies should incorporate invasive plant control given that regeneration of desirable tree species can be influenced by plant invasions and their interactions with herbivores and previous management practices.

Light availability and ungulate browsing determine growth, height and mortality of Abies alba saplings

Ungulate browsing is one of the many factors that affect structure and species composition of forests. Silver fir (Abies alba) is a highly desirable tree species in many European mountain regions, but at the same time one of the most preferred tree species by ungulates. Failure of natural fir regeneration is thus often attributed to browsing.We employ natural light gradients with planted fir saplings but natural browsing to analyze: (i) under which light conditions fir saplings grow and survive best; (ii) where and which ungulate species browse saplings; and (iii) which saplings react and survive best after browsing. The experiment was carried out in a Swiss forest in two fenced plots where parts extended from closed stands into gaps and an unfenced plot under closed canopy. On the three plots 803 fir saplings had been planted in 2008. On half of the total area, browsing had been allowed in at least the winter of 2009/2010.The more light available, the better was the growth of the saplings before and after browsing. For canopy openness⩾11%, some fir saplings had large height increments irrespective of the exact light level. Video surveillance demonstrated that chamois was the only browsing ungulate species. Mortality was positively correlated with light availability, probably due to site preparation, i.e. mainly where ground vegetation was abundant, and with mouse browsing in one plot. Mortality due to chamois or mice was 2.8–16.4% in plots unfenced for one winter and 52% in the plot unfenced for three winters. A small fraction (10%) of browsed saplings that survived used flagging of a twig to form a new leader, and fully compensated for browsing-related height loss. The other saplings showed a partial compensation in the 2nd year after browsing with equally long shoots, but they still remained shorter than unbrowsed saplings. Saplings under a very dense canopy often did not react (7%).The strong impacts of ungulates on fir recruitment are thus more due to the strong preference of the ungulates for this tree species rather than to a low tolerance of fir to browsing. We do not recommend planting firs in forest gaps due to higher mortality rates, since: (1) competition with ground vegetation is higher in gaps, (2) they risk becoming desiccated and (3) mouse browsing is more likely. Thus we provide evidence that A. alba regeneration benefits from moderately shaded conditions.

Regeneration Responses in Partially-Harvested Riparian Management Zones in Northern Minnesota

Trees serve important functions in riparian areas. Guidelines often suggest how riparian forests should be managed to sustain functions, including tree retention and increasing the component of conifers and later-successional species. While regeneration of early successional species is not discouraged, there is uncertainty about the ability to regenerate the latter along with more desirable species. We investigated the regeneration of species differing in successional status and growth forms under different amounts of residual basal area. The study was conducted in riparian sites in northern Minnesota USA. At each site, one portion of the riparian area was uncut, while a downstream area was harvested to 16 or 8 m2·ha-1. Woody vegetation was sampled before and five-years after harvesting and summarized as early, mid-, and late successional hardwoods, as well as conifers and shrubs. After five years, the density of early successional trees was lower at 16 m2·ha-1 compared to 8 m2·ha-1; densities in both treatments were lower than in clearcuts. Densities of mid- and late successional hardwoods and conifers did not increase in either treatment. The higher basal area treatment resulted in a lower density of shrubs, which might be important for establishing more desirable tree species, although this may require additional activities to promote establishment.