Small Saplings Research Articles

Contrasting Regeneration Patterns in Abies alba-Dominated Stands: Insights from Structurally Diverse Mountain Forests across Europe

To maintain the ecosystem resilience to large-scale disturbances in managed forests, it is essential to adhere to the principles of close-to-nature silviculture, adapt practices to the traits of natural forest types, and utilize natural processes, including natural regeneration. This study examines the natural regeneration patterns in silver fir (Abies alba Mill.)-dominated forests, analyzing how the stand structure—tree size diversity, species composition, and stand density—affects the regeneration. We analyze the data from four sites in Poland, Germany, and Italy, employing generalized linear and zero-inflated models to evaluate the impact of the management strategies (even- vs. uneven-aged) and forester-controlled stand characteristics (structural diversity, broadleaf species admixture, and stand density) on the probability of regeneration, its density, and the developmental stages (seedling, small sapling, and tall sapling) across a climatic gradient. Our results indicate a significantly higher probability of regeneration in uneven-aged stands, particularly in areas with lower temperatures and lower overall regeneration density. The tree size diversity in the uneven-aged stands favors advancement from juveniles to more developed stages (seedling to sapling) in places with higher aridity. A denser stand layer (higher stand total basal area) leads to a lower density of natural regeneration for all the present species, except silver fir if considered separately, signifying that, by regulating the stand growing stock, we can selectively promote silver fir. A higher admixture of broadleaf species generally decreases the regeneration density across all the species, except in a water-rich site in the Bavarian Alps, where it had a strong positive impact. These findings underscore the complex interactions of forest ecosystems and provide a better understanding required for promoting silver fir regeneration, which is essential for a close-to-nature silviculture under climate change.

Tree Diversity and Regeneration of a Midhill Community Managed Mixed-Forest of Sindhupalchowk, Nepal

Community forests indeed play a crucial role in the management and conservation of biodiversity, especially in developing countries where poverty can create challenges for enforcing strict rules and regulations. This study focused on analyzing the tree diversity and regeneration in the Anterpu Sallyani Ghaari Community Forest located in the Sindhupalchowk District, Nepal. Data were collected using 30 quadrats, each measuring 10m x 10m, and the sampling method used was random sampling. The study recorded a total of 22 tree species from 16 families. Tree diversity was assessed using the Simpson Index (D) and Shannon-Wiener index (H), and the evenness of the forest was also calculated. Based on the Importance Value Index (IVI), the most dominant tree species were identified as Schima wallichi (DC.) Korth., Pinus roxhborghii Sarg., Castanopsis indica Roxb.Miq., and Lyonia ovalifolia (Wall.) Drude. The overall tree density in the forest was 1080 stems per hectare. The study also reported that the forest has a good seedling density (1310 stems/ ha) but poor sapling density (253 stems/ha). The density-diameter (d-d) curve of adult plants indicated a reverse J-shaped pattern, which is a positive sign as it suggests that the forest is regenerating. However, the low number of small saplings and a slight deviation from the ideal reverse J-shape in the curve indicated unsustainable regeneration. The study suggests that poor management practices and anthropogenic disturbances in the past and present could be contributing factors to the poor regeneration of certain tree species, such as P. roxhborghii. The findings of this study provide insights on the current state of the community forest.

Long-term seedling and small sapling census data from the Barro Colorado Island 50 ha Forest Dynamics Plot, Panama.

Tropical forests are well known for their high woody plant diversity. Processes occurring at early life stages are thought to play a critical role in maintaining this high diversity and shaping the composition of tropical tree communities. To evaluate hypothesized mechanisms promoting tropical tree species coexistence and influencing composition, we initiated a census of woody seedlings and small saplings in the permanent 50 ha Forest Dynamics Plot (FDP) on Barro Colorado Island (BCI), Panama. Situated in old-growth, lowland tropical moist forest, the BCI FDP was originally established in 1980 to monitor trees and shrubs ≥1 cm diameter at 1.3 m above ground (dbh) at ca. 5-year intervals. However, critical data on the dynamics occurring at earlier life stages were initially lacking. Therefore, in 2001 we established a 1-m2 seedling plot in the center of every 5 × 5 m section of the BCI FDP. All freestanding woody individuals ≥20 cm tall and <1 cm dbh (hereafter referred to as seedlings) were tagged, mapped, measured, and identified to species in 19,313 1-m2 seedling plots. Because seedling dynamics are rapid, we censused these seedling plots every 1-2 years. Here, we present data from the 14 censuses of these seedling plots conducted between the initial census in 2001 to the most recent census, in 2018. This data set includes nearly 1 M observations of ~185,000 individuals of >400 tree, shrub, and liana species. These data will permit spatially-explicit analyses of seedling distributions, recruitment, growth, and survival for hundreds of woody plant species. In addition, the data presented here can be linked to openly-available, long-term data on the dynamics of trees and shrubs ≥1 cm dbh in the BCI FDP, as well as existing data sets from the site on climate, canopy structure, phylogenetic relatedness, functional traits, soil nutrients, and topography. This data set can be freely used for non-commercial purposes; we request that users of these data cite this data paper in all publications resulting from the use of this data set.

Woody species response to altered herbivore pressure at Isle Royale National Park

AbstractHerbivores shape vegetative communities via numerous mechanisms, including browse. We used vegetation monitoring data from Isle Royale National Park to examine woody species change across a nine‐year interval, coinciding with herbivore escalation. Here, moose and snowshoe hare are the dominant herbivores, while the gray wolf is the apex predator. Our initial sampling period (2010) followed six years of low moose abundance, while our second sampling event (2019) followed a nine‐year escalation in moose density. We tested for change in both saplings and shrubs and compared diameter size distributions of common tree species in three island sections. We found a decline in large saplings of sugar maple, a species limited to the west section of the island. We also saw declines in small saplings of sugar maple, paper birch, and trembling aspen. For some species, including black spruce and white spruce, taxa that are unpalatable to moose, diameter distributions were proportionally larger (i.e., indicative of fewer small individuals) in 2019 than in 2010. In contrast, diameter distributions of black ash in the central section and trembling aspen in the central and east sections of the island were proportionally smaller (indicative of more small individuals) in 2019 than in 2010. We found that ~50% of common shrub taxa were more abundant during the second sampling event, while none declined. Our work here brings to light several unanticipated results. While we demonstrated partial recovery of trembling aspen, likely originating during the earlier period of low moose abundance, our results suggest further changes may be attributable to other island herbivores. The response of black ash, a hydric species, may be stemming from a sixfold increase in active beaver sites, while that of spruce may be attributable to a historic spike in snowshoe hare density. We currently have only a limited understanding of the impacts of the island's lesser studied herbivores on overstory regeneration. Further research on these linkages can inform decisions addressing controls on forest structure.

UAVs for monitoring responses of regenerating forests under increasing climate change-driven droughts - a review

The impact of climate change-driven droughts on regenerating forests is poorly understood due to the complexities involved in regeneration processes and the difficulties in measuring the relevant parameters with sufficient spatial and temporal resolution in a timely manner. Drought increases tree mortality in both undisturbed and disturbed forests and may influence forest regeneration dynamics from seed germination to the recruitment, growth, and survival of tree seedlings. Seedlings and small saplings may be more susceptible to changes in water availability than larger individuals due to their shallower roots that may be unable to reach the deeper, moist soil layers, and due to uneven competition with adult trees for soil moisture. The potential range shifts and local extinction of drought-sensitive species can also result in changes in forest species community composition and diversity loss at different scales. There is a need for precise and low-cost monitoring systems that facilitate better capturing of the complexities of such processes for restoration measures. The objective of this paper is to study the use of UAVs (Unmanned Aerial Vehicles) for monitoring responses of regenerating forests under increasing climate change-driven droughts. UAVs have several advantages over traditional field-based monitoring techniques and flexibility in selecting the required spatiotemporal resolution over other remote sensing methods, making them a promising tool for monitoring forest recovery. Although further research is required to ensure the accuracy and effectiveness of UAV-facilitated measures for monitoring forest regeneration, UAVs possess great potential in forest management in the event of increasing occurrences of climate-change driven droughts.

Effect of strip clear-cutting on the natural regeneration of Pinus tabuliformis plantations in northeastern China.

In this study, the effect of strip clear-cutting on the natural regeneration performance of mature Pinus tabuliformis plantations in the three locations in western part of the Liaoning Province was analyzed. Strip clear-cutting, with clear-cut and uncut strip widths of 15, 20, 25 m, and 10 and 18 m, respectively, was conducted in spring 2014, and control, in each study location. Field investigations were conducted in 2017. Fifteen sample plots with sizes of 4 m2 (2 m × 2 m) were established in each clear-cut strip, uncut strip, and control. One to four saplings were randomly selected to measure the current year increment, and the lengths and numbers for branch of the first whorl. Three saplings were randomly selected from the center of the strip to measure the photosynthetic rate. Three sample plots with sizes of 4 m2 (2 m × 2 m) and 1 m2 (1 m × 1 m) were developed in each strip and control to determine the biodiversity of shrubs and herbs as well as the water content of the decomposition and semi-decomposition layer. The results show that the current year increment and branch length of the first whorl can be ordered as follows: clear-cut strips > control > uncut strips. Number of the branches of the first whorl can be ordered as follows: clear-cut strips > uncut strips > control. Strip clear-cutting was a statistically significant treatment for the current year increment and length and number of branches of the first whorl. The saplings from the clear-cut strip with a width of 25 m have the largest photosynthetic capacity compared with those from the other strips and control. The transpiration rates of the large, medium, and small saplings from clear-cut strips are the largest and those of saplings from the control are the smallest. The water content of the decomposition and semi-decomposition layer in the control is the highest, but no significant difference was confirmed between the strip clear-cutting approaches.

Population ecology and dynamics of a remnant natural population of European yew Taxus baccata in a lowland temperate forest – implications for use in reforestation

There is increasing focus on reforestation, but the efforts still often include limited subsets of species despite evidence that tree diversity promote biodiversity and ecological resilience. In addition to these benefits, greater inclusion of rare native species in reforestation efforts would also help conserve these species in an uncertain future. Here, we investigate the population ecology and dynamics of the only remaining historical population of the shade‐adapted under‐ and mid‐story tree European yew Taxus baccata in Denmark to inform its potential usage in reforestation. The species has been widely extirpated from European landscapes, and while much used in horticulture, is hardly used in reforestation, so there is limited experience with its requirements and performance. We collected data on all individuals in 2015 and compared them with results from a previous census in 1999. Furthermore, we used boosted regression trees (BRT) modelling to investigate the ecological drivers of the distributions of its different life stages. Our results show a stable T. baccata population, with much regeneration in areas of more open‐canopy conditions that also support high survival between life‐stages. The BRT results show that moss‐dominated microhabitats under moderately shaded conditions are important for T. baccata seedling establishment, while higher light availability is important for survival from sapling to adult life‐stages. For use in reforestation, we recommend providing moderately shaded microhabitats to allow the seedlings and small saplings to escape competition while also acting as protection from herbivores. Through their long‐lived nature, low stature and evergreen foliage, T. baccata would increase the structural complexity of young woodlands, likely enhancing their value for biodiversity, their ecological resilience, as well as their amenity value. Inclusion of T. baccata in reforestation efforts would also aid its spontaneous recolonization of woodland areas, helping it to build larger, more widespread populations with greater resilience to future pressures.

Effect of strip shelterwood-cuts on the crown morphology plasticity of natural regenerated Pinus tabuliformis saplings in northeastern China.

The study analysed the effect of shelterwood-cut strips on the outermost crown profiles and crown characteristics of naturally regenerated Pinus tabuliformis saplings in northeastern China. A total of 49 regenerated saplings from shelterwood-cut strips and 30 from uncut strips were collected. Nonlinear quantile regression was used to develop the outermost crown profile model for the saplings from the shelterwood-cut and uncut strips. The quantile value suitable for describing the outermost crown profiles of the two types of strips was selected using nonparametric boundary regression. The difference in crown morphologies between the shelterwood-cut strips and uncut strips was compared. The results showed that with the same diameter at breast height, the crown radii of the uncut strip saplings were larger than those of the shelterwood-cut strip saplings within the range of 0.2–1.0 for the relative depth into the crown. The largest crown radius of the saplings from the uncut strips was larger than that of the saplings from the shelterwood-cut strips. The inflection points of the shelterwood-cut strip sapling crowns were larger than those of the uncut strip sapling crowns. The crown volume of the small uncut strip saplings was larger than that of the shelterwood-cut strip saplings, and the difference in crown volume decreased with increasing sapling size. The saplings in the early stage of the uncut strips showed a greater growth rate than those of the shelterwood-cut strips, but their growth rate slowed over the long term according to branch-length annual growth. The present study provides a reference for forest management strategy decision making in promoting natural regeneration.

Behavioural flexibility in the courtship dance of golden-collared manakins, Manacus vitellinus

Courtship displays have been traditionally considered stereotyped behaviours. Many elaborate courtships are displayed in specific locations or in courts prepared by the displaying individuals. Sudden environmental events may alter the spatial structure of the displaying site, and individuals should be able to cope with such disruptions. In some mating systems, courtship is the only or main trait used in mate choice. This is the case in lek mating systems where male mating success is highly skewed and intense sexual selection may drive the evolution of elaborate courtship. The golden-collared manakin is a lekking species of the Neotropical forests. Males have an elaborate courtship display that includes a series of acrobatic jumps within a court delimited by small saplings. The courtship ends with a jump on one of the saplings, called the mating sapling, which invites the female to copulate. The display of each male follows a consistent routine that males establish at the beginning of the reproductive season. We hypothesized that males possess behavioural flexibility to adapt their courtship behaviour to unpredictable environmental changes. We investigated the effects of a sudden disruption of the court configuration by placing a piece of bark on the mating sapling. Males gradually established a new display sequence with an alternative mating sapling, demonstrating a high level of behavioural flexibility that suggests the involvement of motor learning. When the bark was removed, some males reverted to the original sequence, showing retention of the original display sequence. Our study provides evidence for the involvement of motor learning in the establishment and adjustment of elaborate courtship displays.

Quantification of Circadian Movement of Small-Leaved Lime (Tilia cordata Mill.) Saplings With Short Interval Terrestrial Laser Scanning.

The goal of the study was to quantify and identify patterns in circadian movements of small-leaved lime (Tillia cordata) saplings with the help of terrestrial laser scanning (TLS). The movements were monitored every 60 min 24 h a day and every 30 min in the hour of sunrise and sunset. In order to exclude wind effects the monitored saplings were indoors. The resulting point clouds were used in creating a time series of branch and foliage movements with high precision. The circadian vertical movement of saplings was evaluated through target points, which has a potential of capturing the point-wise movement more accurately. Our results clearly show that small saplings move their branches and leaves during 24 h in complex ways and that is difficult to identify general patterns. Since we worked with small saplings and our movement threshold was 5 mm, we detected random fluctuation–oscillation as the most common movement in monitored saplings. The results highlight the potential of TLS measurements in support of chronobiology and the possibilities to analyze circadian movements of saplings in controlled environment.

Transforming even-aged coniferous stands to multi-aged stands: an opportunity to increase tree species diversity?

Abstract Transforming even-aged coniferous stands into multi-aged ones is attracting growing interest in Europe. However, applying this silvicultural treatment, maintaining a continuous cover and relying on natural regeneration require a deep understanding of the factors driving interspecific competition in the understorey. In particular, knowledge of species-specific response to different light conditions is needed to plan silvicultural treatments and forecast long-term stand composition. In this context, we assessed regeneration (±10–400 cm in height) and light conditions (±1–40 per cent of transmittance) in nine coniferous stands with ranging stand age (±20–120 years) and species composition (Norway spruce, Douglas fir, larch, silver fir and western hemlock) in Belgium. We then modelled interspecific differences in regeneration height growth to forecast the outcome of interspecific competition in different light conditions. Controlling understorey light seems an efficient way to control the interspecific competition, but with some limits, and taking into account sapling size. Maintaining low light conditions (transmittance &amp;lt; 15 per cent) probably reduces interspecific competition as it allows small saplings (height &amp;lt; 100 cm) of most species to grow at a comparable rate. Maintaining higher light conditions might allow a few species to rapidly overgrow the others. Species ranking in height growth changed across the studied light range only between spruce and larch, suggesting that the competition between these two species can be driven through the control of understorey light. On the other hand, controlling canopy openness was found to be insufficient, for example, to promote an advanced regeneration (height ≥ 200 cm) of fir over advanced regeneration of spruce, to promote any species over western hemlock or to promote Douglas fir. Western hemlock, a very shade-tolerant species, was found to grow three times faster than the other species in all the observed conditions (PACL = 5–20 per cent). Douglas fir saplings showed weak growth and marked defoliation, which we hypothetically relate to the recent outbreak of Contarinia pseudotsugae in Western Europe.

Tree Regeneration Structure Following Beech Bark Disease-Motivated Harvests: Factors Associated with Patterns and Management Implications

In the northern Appalachian region of North America, mortality of mature American beech (Fagus grandifolia Ehrh.) via the introduced beech bark disease (BBD) can result in dense thickets of beech saplings that inhibit the regeneration of other species. It is unknown if similar structures characterize more recently infested managed forests in the Great Lakes region. If these dense beech sapling layers do exist, management would be aided by knowing which site/regional factors they are associated with and by identifying particular sapling structures that may threaten the sustainability of these forests under current management paradigms. To examine these patterns, we used a natural experiment with sample plots in 69 unevenly aged, selection silviculture-managed, maple (Acer spp.)-dominated northern hardwood stands. Our stands were dispersed across northern Michigan, USA and had undergone BBD-motivated partial harvests favoring beech removal (mean = 5.5 years before measurement). In each stand, we quantified tree regeneration structure in relation to winter deer use (fecal pellet count density), site quality (habitat type), geographic region (Eastern Upper Peninsula and Northern Lower Peninsula), and multiple measures of overstory stand density. We also examined the density effects of taller regeneration strata on subordinate strata. Across sites, the small sapling recruit class (i.e., &gt;137 cm tall and &lt;5 cm diameter at 137 cm tall) was dominated by beech and was often dense (44% of subplots &gt; 2000 stems ha−1 and 16% of subplots &gt; 5000 ha−1) but never exceeded the &gt; 10,000 stems ha−1 reported in the northern Appalachian region. Beech sapling density was higher in the Northern Lower Peninsula, on lower quality sites, at lower postharvest overstory densities, and on sites with higher densities of preharvest overstory beech. In contrast to the beech-dominated small sapling recruit class, seedlings (i.e., &lt;25 cm tall) were generally more species diverse than sapling strata and were dominated by maple species. Although generally dense, seedling density was negatively related to small sapling recruit density, suggesting that saplings may suppress the seedling stratum. The general pattern for the small sapling recruit layer of browsing-insensitive beech (and ironwood, Ostrya virginiana Mill. K. Koch) dominance and low representation of browsing-sensitive species (e.g., Acer spp.) circumstantially supports the notion that regeneration structure is heavily influenced by deer. However, current deer use was generally low in our stands, and relationships with tree regeneration structure were weak. Instead, regeneration structure is likely shaped by a combination of factors operating at long time scales (i.e., legacies of deer browsing pressure, selection silviculture (given beech and ironwood are shade tolerant), overstory composition, and site quality) and by those effects that are more proximal, such as postharvest overstory density. Minimum stocking criteria for species considered desirable for management (e.g., sugar maple and Acer saccharum Marshall) suggest many stands are inadequately stocked in the sapling recruit classes. Although future regeneration dynamics are unclear, current patterns suggest that many stands with high beech/ironwood small sapling recruit densities may require management intervention to overcome insufficient recruitment of species targeted for management.

THE NEST, EGGS, AND NESTLING OF COOPMANS"™S ELAENIA Elaenia brachyptera (TYRANNIDAE)

We provide the first descriptions of the nest, eggs, and nestling of Coopmans"™s Elaenia Elaenia brachyptera from the foothills of northeastern Ecuador. We describe 7 active nests, 10 eggs, and 1 mid-aged nestling. Nests are open cups, woven of flexible, pale fibers and rootlets, externally decorated with various loosely-arranged materials. They are placed in small saplings within flat, rocky, river floodplains. Nest placement and architecture make nests difficult to distinguish from naturally accumulated materials left behind by periodic flooding. Clutch size ranged from 1-2 eggs and we estimate incubation to last 15-16 days. Eggs are typical of the genus, buffy to creamy white with small cinnamon and lavender spots and blotches concentrated at the larger end. We also provide a comprehensive review of published literature on the nests, eggs, and breeding ecology for the genus Elaenia, including studies on 30 of the 46 currently recognized taxa.

Patterns and dynamics of canopy-root coupling in tropical tree saplings vary with light intensity but not with root depth.

Carbon (C)dynamics in canopy and roots influence whole-tree carbon fluxes, but little is known about canopy regulation of tree-root activity. Here, the patterns and dynamics of canopy-root C coupling are assessed in tropical trees. Large aeroponicsfacility wasused to study the root systems of Ceiba pentandra and Khaya anthotheca saplings directly at different light intensities. In Ceiba, root respiration (Rr ) co-varied with photosynthesis (An ) in large saplings (3-to-7-m canopy-root axis) at high-light, but showed no consistent pattern at low-light. At medium-light and in small saplings (c. 1-m axis), Rr tended to decrease transiently towards midday. Proximal roots had higher Rr and nonstructural carbohydrate concentrations than distal roots, but canopy-root coupling was unaffected by root location. In medium-sized Khaya, no Rr pattern was observed, and in both species, Rr was unrelated to temperature. The early-afternoon increase in Rr suggests that canopy-root coupling is based on mass flow of newly fixed C in the phloem, whereas the early-morning rise in Rr with An indicates an additional coupling signal that travels faster than the phloem sap. In large saplings and potentially also in higher trees, light and possibly additional environmental factors control the diurnal patterns of canopy-root coupling, irrespective of root location.

The partitioning of gross primary production for young Eucalyptus tereticornis trees under experimental warming and altered water availability.

The allocation of carbon (C) is an important component of tree physiology that influences growth and ecosystem C storage. Allocation is challenging to measure, and its sensitivity to environmental changes such as warming and altered water availability is uncertain. We exposed young Eucalyptus tereticornis trees to +3°C warming and elimination of summer precipitation in the field using whole-tree chambers. We calculated C allocation terms using detailed measurements of growth and continuous whole-crown CO2 and water exchange measurements. Trees grew from small saplings to nearly 9m height during this 15-month experiment. Warming accelerated growth and leaf area development, and it increased the partitioning of gross primary production (GPP) to aboveground respiration and growth while decreasing partitioning below ground. Eliminating summer precipitation reduced C gain and growth but did not impact GPP partitioning. Trees utilized deep soil water and avoided strongly negative water potentials. Warming increased growth respiration, but maintenance respiration acclimated homeostatically. The increasing growth in the warmed treatment resulted in higher rates of respiration, even with complete acclimation of maintenance respiration. Warming-induced stimulations of tree growth likely involve increased C allocation above ground, particularly to leaf area development, whereas reduced water availability may not stimulate allocation to roots.

Browse-Mediated Succession by Deer and Elk 40 Y After a Clearcut in Northern Lower Michigan

In 2017 we sampled tree stems in a clearcut generated in 1977 in the Pigeon River State Forest, Michigan and compared results to three previous sampling periods completed in 1983, 1988, and 1999, respectively. Trees were recorded by species, height class, and whether or not stems had been browsed by mammalian herbivores and whether stems were alive or dead. The results show the most preferred browse tree species when the clearcut was young (bigtooth aspen) was completely absent by 1999 and thereafter, and tree species richness increased over time. Elk were still using the area in 2017, as shown by the presence of pellet groups and sightings in the clearcut and nearby, but little noticeable browse damage was seen in 1999 or 2017, and tree mortality was negligible in 2017. A total of 22 tree species were identified across the time period, but only five species were recorded as present in all years. A total of 11 species were recorded in 1 y only: six in 1999 and five in 2017. Many species were rare, as defined by relative abundances of <0.01, and relative abundances varied a great deal across time. Stochastic dispersal, establishment, and mortality events likely explain many of these observations, given high mortality rates of seedlings and small saplings due to browsing earlier in succession, and competition for light or other resources as trees aged over time.

Fir expansion not controlled by moderate densities of large herbivores: a Mediterranean mountain grassland conservation issue

Whilst livestock has maintained grasslands over centuries in south European mountains, current ungulate densities are insufficient to control tree and forest expansion effectively. The present results based on fir population dynamics and radial/height growth raise questions about the sustainable management of new forests that are former mountain grasslands. This empirical case study contributes to debate about methods for long-term management of grasslands in Mediterranean mountains. Forest expansion following the cessation of grazing is a threat to biodiversity in mountain grasslands that are components of Mediterranean cultural landscapes. We hypothesised that ungulates could mitigate tree recruitment, thus conserving mountain grasslands. We tested the efficiency of grazing and browsing by domestic and wild ungulates (sheep, roe and red deer) at inhibiting silver fir (Abies alba Mill.) encroachment in a conservation area, one of the main browsed trees. The fir trees’ age structure was analysed by dendrochronology, and the individual growth patterns and scars were recorded in their tree-ring series. Fir density has increased since the 1960s, simultaneously with the increase in ungulate populations. The scar occurrences only appeared during the 1970s. Most scars were observed on seedlings and small saplings. The impacts of ungulates are observed on the radial and height growth of trees, mostly on trees < 100 cm, but it did not however result in controlling the recruitment of fir. The hypothesis that a moderate density of ungulates might inhibit tree encroachment is therefore rejected, even in the case of a highly palatable species such as silver fir. Ungulates, solely, would not be an appropriate policy for grassland conservation in Mediterranean mountains.

Controlling One-Seed Juniper Saplings With Small Ruminants: What We Have Learned

On the Ground • Protein supplements and polyethylene glycol increased juniper intake by small ruminants in all seasons except fall, when PSM concentrations were greatest. • Terpenes were affected by season and sapling size, and were related to juniper intake by small ruminants. • Small sapling browsing occurred most frequently in summer. Debarking of branches on taller saplings was greatest in spring. • Ten years later, juniper kill ranged from 5-14%. Growth suppression was still evident after 10 years; browsed saplings averaged 13 cm shorter than controls. • Strategies to target grazing of one-seed juniper are more likely to succeed if aligned with periods when PSM are lowest.

Spatial distribution of display sites of Grey Peacock-pheasant in relation to micro-habitat and predators during the breeding season

BackgroundThe destruction and fragmentation of forest in Southeast Asia is accelerating biodiversity loss, resulting in a range of management and conservation actions. For some species, a detailed understanding of microhabitat selection is critical for this, especially in the breeding season.MethodsTo understand the factors that explain how specific habitats are used by the Grey Peacock-pheasant (Polyplectron bicalcaratum) in the breeding season, we used camera trapping and microhabitat sampling to assess the microhabitat selection of males. We also looked at their interaction with predators in an area of 1200 m × 1200 m at the Huai Kha Khaeng Wildlife Sanctuary, Thailand, between January and May 2013.ResultsWe show that display scrapes are situated on flatter open areas with small saplings and some vines, typified by low horizontal understory density. We hypothesise that this allows a trade-off between courtship display and the avoidance of predators. Our study showed that the position of Grey Peacock-pheasant display scrapes regularly overlapped with predators within the same microhabitat. We hypothesise that the species’ behavioural responses to temporal variation in predation risk allows them to avoid most predators.ConclusionsParticular microhabitats are required for Grey Peacock-pheasant display. They avoid predators at these places by being active when predators are not.

Ontogenetic changes in insect herbivory in birch (Betula pubesecens): The importance of plant apparency

Abstract Several theories aim at predicting changes in the interactions between plants and herbivores over the lifetime of a plant. Hypotheses based on ontogenetic changes in resource allocation to plant defence and in plant apparency lead to partly opposing predictions regarding the differences in levels of herbivory between juvenile and mature plant individuals. We tested these predictions by measuring background foliar losses to insects in saplings and mature trees of downy birch (Betula pubescens) in ten sites along a latitudinal gradient from 60° to 69°N in boreal forests of Northern Europe. The percentage of consumed leaf area increased, and the variation in the levels of herbivory among plant individuals decreased, for tree sizes ranging from small saplings (2–12 cm tall) to large saplings (13–80 cm tall) and then to mature trees (3–18 m tall). Small saplings had higher foliar quality for insects, as indicated by better performance of leafmining larvae of Eriocrania semipurpurella and by greater specific leaf area, compared with large saplings and mature trees. The average percentage of leaf area consumed from a damaged leaf, which reflects the inducibility of local defence responses to insect damage, did not vary among the birch size classes. The foliar losses to insects decreased nearly fivefold with an increase in latitude from 60° to 69°N, but the relative differences in these losses among the birch size classes were independent of latitude. Our findings fit well with the predictions based on a plant apparency hypothesis, but do not support predictions based on ontogenetic changes in resource allocation to plant antiherbivore defences. We conclude that the generally overlooked effects of apparency on plant damage by insects can explain, at least in some cases, the frequently observed lack of correspondence between the levels of plant defences and herbivory. A plain language summary is available for this article.