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Global forests are increasingly lost to climate change, disturbance, and human management. Evaluating forests' capacities to regenerate and colonize new habitats has to start with the seed production of individual trees and how it depends on nutrient access. Studies on the linkage between reproduction and foliar nutrients are limited to a few locations and few species, due to the large investment needed for field measurements on both variables. We synthesized tree fecundity estimates from the Masting Inference and Forecasting (MASTIF) network with foliar nutrient concentrations from hyperspectral remote sensing at the National Ecological Observatory Network (NEON) across the contiguous United States. We evaluated the relationships between seed production and foliar nutrients for 56,544 tree‐years from 26 species at individual and community scales. We found a prevalent association between high foliar phosphorous (P) concentration and low individual seed production (ISP) across the continent. Within‐species coefficients to nitrogen (N), potassium (K), calcium (Ca), and magnesium (Mg) are related to species differences in nutrient demand, with distinct biogeographic patterns. Community seed production (CSP) decreased four orders of magnitude from the lowest to the highest foliar P. This first continental‐scale study sheds light on the relationship between seed production and foliar nutrients, highlighting the potential of using combined Light Detection And Ranging (LiDAR) and hyperspectral remote sensing to evaluate forest regeneration. The fact that both ISP and CSP decline in the presence of high foliar P levels has immediate application in improving forest demographic and regeneration models by providing more realistic nutrient effects at multiple scales. [ABSTRACT FROM AUTHOR]

Cedrela odorata L. was introduced as a possible forest restauration species in classified forests at Côte d'Ivoire. Because of its demonstrated invasive behavior in other tropical forests, this study aimed to assess the impact of Cedrela odorata on the regeneration of spontaneous plant species in tree plantations. On the base of Cedrela odorata larger tree densities, two types of forest plantation were considered: Type I (240 stems/ha) and Type II (176 stems/ha). In these plantations, plots with 0.25 ha were chosen to locate each tree with dbh = 2.5 cm, in an orthonormal reference. The tree density, the basal area, the species richness, the Shannon diversity index and the rank-abundance curves were determined considering smaller and larger trees. The horizontal spatial arrangement and Ripley's K function were performed to understand the spatial relationship between Cedrela odorata smaller trees and those of spontaneous species. The results shown lower spontaneous plant species richness (15-20 species) and diversity (1.15 - 1.43); the dominance of Cedrela odorata smaller trees (43.02 - 62.95 % of all stems). The Cedrela odorata smaller trees and those of other species have dependent spatial distributions; expressed by a spatial repulsion between the two groups up to a distance of 18 m in the most densified forest plantation. This repulsion was related to an aggregated distribution of Cedrela odorata smaller trees in plantation with higher tree density. The study suggests a 170-stems/ha (or lower) of Cedrela odorata planting density for biodiversity establishment improvement outcomes in forest plantations. [ABSTRACT FROM AUTHOR]

Large, severe fires are becoming more frequent in many forest types across the western United States and have resulted in tree mortality across tens of thousands of hectares. Conifer regeneration in these areas is limited because seeds must travel long distances to reach the interior of large burned patches and establishment is jeopardized by increasingly hot and dry conditions. To better inform postfire management in low elevation forests of California, USA, we collected 5-yr postfire recovery data from 1,234 study plots in 19 wildfires that burned from 2004-2012 and 18 yrs of seed production data from 216 seed fall traps (1999-2017). We used these data in conjunction with spatially extensive climate, topography, forest composition, and burn severity surfaces to construct taxon-specific, spatially explicit models of conifer regeneration that incorporate climate conditions and seed availability during postfire recovery windows. We found that after accounting for other predictors both postfire and historical precipitation were strong predictors of regeneration, suggesting that both direct effects of postfire moisture conditions and biological inertia from historical climate may play a role in regeneration. Alternatively, postfire regeneration may simply be driven by postfire climate and apparent relationships with historical climate could be spurious. The estimated sensitivity of regeneration to postfire seed availability was strongest in firs and all conifers combined and weaker in pines. Seed production exhibited high temporal variability with seed production varying by over two orders of magnitude among years. Our models indicate that during droughts postfire conifer regeneration declines most substantially in low-to-moderate elevation forests. These findings enhance our mechanistic understanding of forecasted and historically documented shifts in the distribution of trees.

Highly disturbed forests are commonplace throughout the eastern United States and their residing composition and structure is reflective of their past land use. Management and restoration efforts are complicated by diverse and abundant nonnative invasive plants, including Ailanthus altissima. Verticillium nonalfalfae has been identified as a potential native mycoherbicide option for Ailanthus. To test the efficacy of Verticillium on Ailanthus we designed a study in highly disturbed forests of southern Ohio. At each of five sites, we monitored symptomology, mortality, and rate of spread of stem-inoculated Verticillium on Ailanthus in four inoculated plots and compared it to a control plot. We also monitored native plants for Verticillium symptomology and community responses to Ailanthus control. Our results suggest that Verticillium is an effective tool for controlling Ailanthus with no observed effect on native flora. Further, Verticillium naturally spreads through stands and mortality is slow enough that other resident nonnative invasive plants do not rapidly increase. [ABSTRACT FROM AUTHOR]

Masting is the synchronous and highly variable production of fruit within a population. Although several hypotheses have been proposed to explain why and how masting evolved in plants as a reproductive strategy, the factors that trigger a large reproductive effort in a particular year are still not well understood. While both weather and resources have been proposed to play an important role, testing these hypotheses has been challenging due to a lack of long-term data and appropriate experimental designs. In this manuscript, we used 18 years of acorn production data to analyze the relationship between resources, weather, and masting in black oak (Quercus velutina) and chestnut oak (Q. montana). The data were collected in southeast Ohio as part of the Fire and Fire Surrogate (FFS) study, which applied silvicultural treatments (i.e., thinning and prescribed fires) to reduce competition and manipulate resources. We found species-specific responses to the thinning and fire treatments, with an overall increase in acorn production for chestnut oak in the thin + burn treatment and an increase for black oak in the thin-only treatment compared to the control. Chestnut oak reproduction also had strong positive relationships with warm spring temperatures, and a positive change in summer temperatures compared to the previous year (i.e., summer temperatures that went from cool to warm). For black oak, warm spring temperatures increased acorn production while later starts to spring warming the year before decreased acorn production. These results support the hypotheses that both resources and weather (as a cue and as a limiting factor) are important for masting in oaks. Thus, both factors should be included in predictive models for acorn production under current and future climate conditions. [ABSTRACT FROM AUTHOR]

Agricultural activities such as crop production and cattle ranching are rapidly replacing forests worldwide, especially in the tropics. Resulting forest loss can adversely affect biodiversity in many ways, including trajectories of community reassembly, community composition, forest structural profiles and taxonomic diversity. Yet, effects of forest loss on specific ecosystem functions remain limited. Processes closely linked with tree reproduction, such as pollination and seed dispersal are of paramount importance for many ecological functions in tropical forests. Disruption in these processes is known to delay or change forest regeneration, diversity and structural dynamics.To explore how reproductive and dispersal traits are being altered by landscape‐scale deforestation, we surveyed and compiled trait data for tree communities in 20 tropical Atlantic rainforest remnants in northeastern Brazil, across a gradient of deforested landscapes, each retaining 3%–93% forest cover.The functional richness of reproductive plant attributes decreased as the amount of forest cover decreased, while divergence increased along the same gradient. Loss of forest cover disproportionately affected certain dispersal and reproductive attributes, with most heavily impacted functional attributes including: brief flowering duration, hermaphrodite sexual system, and zoochoric dispersal mode. We identified a clear threshold at 25–30% of forest cover, below which, reproductive attributes disappeared more quickly than expect from forest remnants.Synthesis. Deforestation may impair tree community functional diversity, particularly by decreasing the number of functions. Under scenarios of extensive deforestation, changes to reproductive and dispersal trait profile of forest communities suggest that profound modifications in the availability of floral and seed resources are likely to be substantial. Such extensive changes to food supply of pollinating and dispersing animals suggest carry‐over effects to the fauna of these important forest systems. [ABSTRACT FROM AUTHOR]

Highlights • We quantified realised genetic gain for Norway spruce. • Six improved groups were studied in four experiments in central Sweden. • The differences in single tree properties and areal production were studied. • All genetically improved groups produced higher volumes than unimproved local provenances. • The differences were greater for areal production than for early measured height. Abstract Six groups of Norway spruce (Picea abies L. Karst) plants with varying levels of genetic gain and unimproved local provenances were compared in four realised gain trials at four sites in central Sweden. The groups were planted separately in experimental plots and compared in terms of survival rate and height 4 years after planting, as well as survival rate, height, diameter and areal volume production 13–16 years after planting. The genetically improved groups all produced higher volumes than the unimproved local provenances, and the clonal bulk of 23 full-sib families' volume production per unit area was 56% higher than that of local provenances. The genetic groups followed expected levels of genetic gain, except for individual clones (which varied substantially in performance) and full-sib families. There were greater relative differences between local provenances and genetic groups in areal volume production 13–16 years after planting than in height at 4 years after planting. The results confirm that growth of improved genetic groups is largely consistent with expected values of realized genetic gain. They also indicate that clonal mixes rather than one or a few clones should be deployed in clonal forestry. The comparison of early measured height with areal production showed that early height measurements are good indicators of realized genetic gain and differences in areal production are greater than early differences in height. [ABSTRACT FROM AUTHOR]

Highlights • Selection cutting treatments emulated natural diameter structures and gap sizes. • Moderate and heavy cutting intensities promoted yellow birch and species richness. • Heavy selection treatment decreased the abundance of large trees. • Moderate intensity treatment was the best compromise for regeneration and diversity. • Enrichment planting could be necessary to regenerate declining red spruce. Abstract Traditional silvicultural systems such as clearcutting and single-tree selection cutting are critiqued for their tendency to simplify forest complexity. By more closely emulating natural disturbance regimes and increasing the availability and heterogeneity in understory light levels, we pose that systems causing intermediate disturbances such as the single-tree and small group selection cutting system can promote tree regeneration, retain stand structural attributes, and maintain high understory plant diversity in temperate mixedwood stands. To assess this, we implemented a harvest intensity gradient experiment (residual basal area [BA], % removal) consisting of uncut control (26 m2/ha, 0%), light (21 m2/ha, 20%), moderate (18 m2/ha, 31%) and heavy (15 m2/ha, 42%) cutting with retention of legacy trees in uneven-aged yellow birch (Betula alleghaniensis Britton) – conifer stands. We evaluated the effects on gap size, light transmittance, abundance of living and dead trees, plant diversity, and regeneration of target species (i.e. yellow birch, red spruce [ Picea rubens Sarg.] and balsam fir [ Abies balsamea L.]), during the 8 years postcut. Moderate and heavy single-tree and small group selection cutting treatments triggered changes in microenvironments and in understory plant community. Moderate and heavy selection had greater yellow birch seedling density > 30 cm in height compared to the control. Cutting treatments did not significantly improve red spruce and balsam fir regeneration, despite favorable micro-environmental conditions (e.g. gaps averaging 200–350 m2 and 15–40% transmitted light). The vascular plant community rebounded quickly after disturbance and harvesting did not depress any diversity metric or alter community composition beyond control levels. Tree species richness increased in moderate and heavy selection cuts, while vascular species diversity (H′) was greatest in the heavy selection cut. Observed richness and diversity gains were driven by augmented yellow birch and mountain maple (Acer spicatum Lam.) recruitment into larger classes as well as greater forb, tree, and shrub cover in response to greater cutting intensities. Species richness and diversity were positively correlated with increased light availability, but not with light heterogeneity. Our results show that this hybrid selection cutting system benefits yellow birch recruitment without negatively impacting plant diversity. However, because increasing harvest intensity simultaneously enhanced interfering non-commercial species abundance (e.g. mountain maple), failed to improve red spruce regeneration, and decreased the abundance of large trees (diameter at breast height > 29 cm), we caution to opt for moderate cutting intensity in this forest type. Additional treatments such as enrichment planting in harvest gaps might be necessary to maintain red spruce over time. [ABSTRACT FROM AUTHOR]

Highlights • Regeneration development can be modeled with understory and overstory attributes. • High canopy cover and low structural diversity slowed juvenile height development. • Competition from taller juveniles substantially slowed height development. • Silver fir reached a browsing-free height of 2 m faster than Norway spruce. • Fir-dominated cohorts had a stronger impact on spruce density than vice-versa. Abstract The timely establishment of natural regeneration of the preferred species after the death or removal of mature trees is essential in continuous-cover forestry. In the context of the gradual shift from even-aged and monospecific to uneven-aged and/or mixed forest stands, the limited availability of statistical models to predict seedling establishment, survival, and growth has increasingly become a bottleneck for forest management planning and, ultimately, a potential limitation to a wider adoption of alternative silvicultural approaches. We investigated the development of top height and density of natural regeneration in 19 uneven-structured, mixed silver fir (Abies alba Mill.) and Norway spruce (Picea abies (L.) H. Karst.) stands in southwestern Germany using long-term observations (35 years) from permanent plots. We used linear mixed-effects models to analyze the influence of overstory and understory-related variables on regeneration of fir and spruce. The height of the five tallest juvenile trees per regeneration subplot and species increased significantly with diminishing canopy cover and increasing structural diversity of the overstory. However, competition exerted by tall juveniles substantially impacted the development of smaller neighbors, which were less able to profit from favorable overstory conditions. These results indicate that canopy cover and structural diversity need to be taken into account when modeling height development of juvenile trees in irregular stands. Importantly, these results also demonstrate the potential of silvicultural interventions to shorten the time period when terminal shoots are vulnerable to browsing. Densities of juvenile trees displayed a unimodal relationship with the mean height of the regeneration. Fir and spruce densities culminated at a mean height of approx. 50 cm and decreased rapidly afterwards. This pattern indicates an early onset of competition within the regeneration layer. For both species, juvenile densities were unrelated to overstory structural diversity, yet they showed positive relationships with overstory density and site productivity. Overall, fir juveniles developed faster in height than spruce juveniles. Even rather rapid group-shelterwood cutting regimes with complete canopy removal within two decades still favored fir regeneration. In addition, a high proportion of fir in the regeneration cohort had a stronger negative effect on spruce juvenile density than vice versa. Since spruce is less shade-tolerant than fir, it is likely that fir will dominate the future stand composition. Overall, our models provide the basis to predict natural regeneration dynamics in structurally complex stands dominated by fir and spruce and to further evaluate alternative treatment scenarios. [ABSTRACT FROM AUTHOR]

Production of wood charcoal is a traditional form of forest use that lasted for millennia in most temperate regions, vanishing only some decades ago in the Mediterranean countries. Here, the abandoned charcoal hearths form a network of microhabitats with peculiar vegetation and soil conditions. Previous observational studies showed that establishment of woody species at these sites is severely hindered for unknown reasons. To test the effects of charcoal hearth soil on tree growth we used a common garden experiment with three major Euro-Mediterranean forest trees with different traits and ecology, one evergreen ( Quercus ilex, holm oak) and two deciduous ( Fagus sylvatica , beech, and Quercus cerris , Turkey oak). These were sown on control and charcoal-enriched soil collected in forest hearths abandoned since decades. Seed germination, seedling growth, photosynthetic efficiency and mortality were measured over a period of two years. Some responses were species-specific, while others were possibly associated to key traits such as evergreen vs. deciduous habit. Although charcoal soil effects were mainly positive on growth rate (height increase), they were mostly negative on germination of beech seeds, survival of holm oak seedlings, and photosynthetic efficiency. Although total biomass was not significantly affected, the root:shoot ratio was increased as a possible effect of physiological drought on hearth soil. These results support field-based evidence that the long persistence of charcoal remains in the soil may be not a favourable condition for forest regeneration. Management implications concern the use of biochar practices to promote forest restoration, which should be further tested on a wide range of species in different life-stages before applications in the field, also considering its long-term consequences. [ABSTRACT FROM AUTHOR]

The article discusses the study conducted to reproduce trees and to improve the life and structure of the trees in the U.S. It was said that the next stage of the relationship between man and the forest will possibly be known to their descendants as the time in history when forest trees were domesticated in the U.S. Some organized gathering of seed from the best-looking trees in the hope of improving the breed, the large plantations have not been laboratories for selective breeding aimed at developing desirable traits such as straight trunks, superior wood, and resistance to disease.

Wildfires, insect outbreaks, and windstorms are increasingly common forest disturbances. Post-disturbance management often involves salvage logging, i.e., the felling and removal of the affected trees; however, this practice may represent an additional disturbance with effects on ecosystem processes and services. We developed a systematic map to provide an overview of the primary studies on this topic and created a database with information on the characteristics of the retrieved publications, including information on stands, disturbance, intervention, measured outcomes, and study design. Of 4341 retrieved publications, 90 were retained in the systematic map. These publications represented 49 studies, predominantly from North America and Europe. Salvage logging after wildfire was addressed more frequently than after insect outbreaks or windstorms. Most studies addressed logging after a single disturbance event, and replication of salvaged stands rarely exceeded 10. The most frequent response variables were tree regeneration, ground cover, and deadwood characteristics. This document aims to help managers find the most relevant primary studies on the ecological effects of salvage logging. It also aims to identify and discuss clusters and gaps in the body of evidence, relevant for scientists who aim to synthesize previous work or identify questions for future studies. [ABSTRACT FROM AUTHOR]

Abstract: Life‐history theory posits that trade‐offs between demographic rates constrain the range of viable life‐history strategies. For coexisting tropical tree species, the best established demographic trade‐off is the growth‐survival trade‐off. However, we know surprisingly little about co‐variation of growth and survival with measures of reproduction. We analysed demographic rates from seed to adult of 282 co‐occurring tropical tree and shrub species, including measures of reproduction and accounting for ontogeny. Besides the well‐established fast–slow continuum, we identified a second major dimension of demographic variation: a trade‐off between recruitment and seedling performance vs. growth and survival of larger individuals (≥ 1 cm dbh) corresponding to a ‘stature–recruitment’ axis. The two demographic dimensions were almost perfectly aligned with two independent trait dimensions (shade tolerance and size). Our results complement recent analyses of plant life‐history variation at the global scale and reveal that demographic trade‐offs along multiple axes act to structure local communities. [ABSTRACT FROM AUTHOR]

Mining in the Athabasca Oil Sands Region (AOSR) has contributed extensively to increased exposure of wildlife to naturally occurring polycyclic aromatic compounds (PACs), yet little is known about the toxicity of PACs to wildlife in this region. We identified reproductive and developmental changes in tree swallows ( Tachycineta bicolor ) breeding in close proximity to mining-related activities in the AOSR, and determined these changes in relation to the birds' exposure and accumulation of 41 PACs (parent-, alkylated-PAHs), dibenzothiophenes (DBTs; previously published), diet (carbon (δ 13 C), nitrogen (δ 15 N)), volatile organic compounds, and weather variables. Tree swallow pairs (N = 43) were compared among mining-related (OS1, OS2) and reference (REF1, REF2) sites. At OS2, clutch initiation was slightly advanced (2012) but reproductive success (65%) was much lower than at the other sites (≥ 79%). Fledgling production by each pair was influenced by the timing of clutch initiation (years combined); in a highly inclement brood rearing period (2013), additional influences included the nestlings' exposure to ΣDBTs, accumulation of C1-naphthalene, the trophic position of the prey in their diet (δ 15 N), and record-breaking rainfall. Nestlings at OS2 were significantly lighter at day (d) 9 and d14, and in poorer body condition (d9). Nestling body mass was influenced by multiple stressors that varied by site: mass of younger nestlings (d9) was related to dietary source (δ 13 C; e.g., wetlands, terrestrial fields), exposure and/or accumulation of C1-phenanthrenes, C2-fluorenes, Σalkyl-PAHs and ΣDBTs, while for older nestlings (d14), body mass was related to sex, hatch date and/or rainfall during brood rearing. The swallows' exposure and accumulation of parent-PACs, alkyl-PACs and DBTs, the timing of hatching, their diet and exposure to highly inclement rains, contributed to their reproductive and developmental changes. [ABSTRACT FROM AUTHOR]

Abstract: Selective logging in tropical rain forests may promote population growth of invasive plants. The ability of invaders to respond, specifically in reproductive traits, to increase in resource abundance may allow them to increase their presence in the seed rain of recipient communities. The invasive pioneer tree Bellucia pentamera (Melastomataceae) is currently spreading within Gunung Palung National Park in West Kalimantan, Indonesia. The park has also experienced periods of illegal, small‐scale, selective logging that seem to have facilitated population growth and spread of this invader. We first used fruiting frequency as a proxy for fruit output to make comparisons between B. pentamera and the native tree community of over 200 genera. We then constructed two Generalized Linear Autoregressive Moving Average (GLARMA) models using 13 months of phenology data to predict both fruiting frequency and crop size of B. pentamera under selective logging versus natural treefall disturbance regimes. Bellucia pentamera fruited at considerably higher frequency than all 200 native genera considered. This invader also responded positively to selective logging with both odds of being in fruit and crop sizes at least doubling in logged plots. Prolific seed output of B. pentamera is especially problematic within the lottery competition of tropical rain forest gap tree communities, in which prominence in the seed rain is particularly important. Furthermore, the reproductive response of B. pentamera to selective logging suggests that this harvesting practice may have a considerable role in facilitating this invasion in Southeast Asia. [ABSTRACT FROM AUTHOR]

Masting is the highly variable and synchronous production of seeds by plants. Masting can have cascading effects on plant population dynamics and forest properties such as tree growth, carbon stocks, regeneration, nutrient cycling, or future species composition. However, masting has often been missing from forest models. Those few that simulate masting have done so using relatively simple empirical rules, and lack an implementation of process-based mechanisms that control such events. Here we review more than 200 published papers on mechanistic formulations of masting, and summarize how the main processes involved in masting and their related patterns can be incorporated in forest models at different degrees of complexity. Our review showed that, of all proximate causes of masting, resource acquisition, storage and allocation were the processes studied most often. Hormonal and genetic regulation of bud formation, floral induction, and anthesis were less frequently addressed. We outline the building blocks of a general process-based model of masting that can be used to improve the oversimplified functions in different types of forest models, and to implement them where missing. A complete implementation of masting in forest models should include functions for resource allocation and depletion, and for pollination, as regulated by both forest structure and weather in the years prior to seed production. When models operate at spatio-temporal scales mismatched with the main masting processes, or if calibration data are not available, simulation can be based on parameterizing masting patterns (variability, synchrony, or frequency). Also, observed masting patterns have the potential to be used as “reality checks” for more process-based forest models wishing to accurately reproduce masting as an emergent phenomenon. [ABSTRACT FROM AUTHOR]

The reproductive system of a tree species has substantial impact on genetic diversity and structure within and among natural populations. Such information, should be considered when planning tree planting for forest restoration. Here, we describe the mating system and genetic diversity of an overexploited Neotropical tree, Myroxylon peruiferum L.f. (Fabaceae) sampled from a forest remnant (10 seed trees and 200 seeds) and assess whether the effective population size of nursery-grown seedlings (148 seedlings) is sufficient to prevent inbreeding depression in reintroduced populations. Genetic analyses were performed based on 8 microsatellite loci. M. peruiferum presented a mixed mating system with evidence of biparental inbreeding ( tm - ts = 0.118). We found low levels of genetic diversity for M. peruiferum species (allelic richness: 1.40 to 4.82; expected heterozygosity: 0.29 to 0.52). Based on Ne(v) within progeny, we suggest a sample size of 47 seed trees to achieve an effective population size of 100. The effective population sizes for the nursery-grown seedlings were much smaller (Ne = 2754-34.86) than that recommended for short term (Ne ≥ 100) population conservation. Therefore, to obtain a reasonable genetic representation of native tree species and prevent problems associated with inbreeding depression, seedling production for restoration purposes may require a much larger sampling effort than is currently used, a problem that is further complicated by species with a mixed mating system. This study emphasizes the need to integrate species reproductive biology into seedling production programs and connect conservation genetics with ecological restoration. [ABSTRACT FROM AUTHOR]

Abstract: Lianas are a key component of tropical forests, where they compete intensely with trees, reducing tree recruitment, growth and survival. One of the most important potential outcomes of liana competition is the reduction of tree reproduction; however, no previous study has experimentally determined the effects of lianas on tree reproduction beyond a single tree species. We used a large‐scale liana removal experiment to quantify the effect of lianas on community‐level canopy and understorey tree and palm reproduction. In 2011, we removed lianas from eight 6,400‐m2 plots (eight plots served as controls) and surveyed understorey tree reproduction in 2012, canopy tree and palm reproduction in 2013, and a second census of all plants in 2016. We found that lianas significantly reduced canopy tree community flowering and fruiting after liana removal. Two years after liana removal, the number of canopy trees with fruits was 173% higher, fruiting individuals had 50% more of their canopy covered by fruits and the number of tree species with fruits was 169% higher than in control plots where lianas were present. Five years after liana removal, the number of canopy trees with fruits was 150% higher, fruiting individuals had 31% more of their canopy covered by fruits and the number of tree species with fruits was 109% higher than in unmanipulated control plots. Liana removal had only a slight positive effect on palms and on understorey tree flower and fruit production, even though understorey light levels had increased 20% following liana cutting. Synthesis. Our findings provide the first experimental demonstration that competition from lianas significantly reduces community‐level canopy tree reproduction. Reduced reproduction increases canopy tree seed and dispersal limitations, and may interfere with deterministic mechanisms thought to maintain tropical canopy tree species diversity, as well as reduce food availability to many animal species. Because lianas are increasing in abundance in many neotropical forests, the effects of lianas on tree reproduction will likely increase, and if the effects of lianas on tree reproduction vary with tree species identity, lianas ultimately could have a destabilizing effect on both tree and animal population dynamics. [ABSTRACT FROM AUTHOR]

Abstract: Predicting the fate of tropical forests under a changing climate requires understanding species responses to climatic variability and extremes. Seedlings may be particularly vulnerable to climatic stress given low stored resources and undeveloped roots; they also portend the potential effects of climate change on future forest composition. Here we use data for ca. 50,000 tropical seedlings representing 25 woody species to assess (i) the effects of interannual variation in rainfall and solar radiation between 2007 and 2016 on seedling survival over 9 years in a subtropical forest; and (ii) how spatial heterogeneity in three environmental factors—soil moisture, understory light, and conspecific neighborhood density—modulate these responses. Community‐wide seedling survival was not sensitive to interannual rainfall variability but interspecific variation in these responses was large, overwhelming the average community response. In contrast, community‐wide responses to solar radiation were predominantly positive. Spatial heterogeneity in soil moisture and conspecific density were the predominant and most consistent drivers of seedling survival, with the majority of species exhibiting greater survival at low conspecific densities and positive or nonlinear responses to soil moisture. This environmental heterogeneity modulated impacts of rainfall and solar radiation. Negative conspecific effects were amplified during rainy years and at dry sites, whereas the positive effects of radiation on survival were more pronounced for seedlings existing at high understory light levels. These results demonstrate that environmental heterogeneity is not only the main driver of seedling survival in this forest but also plays a central role in buffering or exacerbating impacts of climate fluctuations on forest regeneration. Since seedlings represent a key bottleneck in the demographic cycle of trees, efforts to predict the long‐term effects of a changing climate on tropical forests must take into account this environmental heterogeneity and how its effects on regeneration dynamics play out in long‐term stand dynamics. [ABSTRACT FROM AUTHOR]

Imputation models were developed to predict seedling regeneration density and composition on National Forest System (NFS) lands in Oregon and Washington. The models were based on Forest Inventory and Analysis and Pacific Northwest Regional NFS Monitoring data. Individual models were developed based on broad forest plant association groups (FPAGs) with all model development and analysis conducted in R using a most similar neighbor-like imputation approach. Model performance was evaluated based on bias, mean absolute deviation, root mean-squared error (RMSE), and error rate in correctly predicting the total presence or absence of any regenerating species regardless of species (Total ER). Low to moderate RMSE (≤7400 regeneration stems ha −1 ) and low to moderate Total ER (≤50%) were observed for 25 out of 58 FPAG-specific models. The regeneration imputation models produced in this study represent a large first step towards developing flexible, expandable, and adaptable regeneration models that can be easily incorporated into existing growth models like the Forest Vegetation Simulator. [ABSTRACT FROM AUTHOR]

We studied regeneration dynamics in forests disturbed by three different windthrow events in 2008 in Slovenia to assess the success of natural regeneration vs planting and subsequent silvicultural treatments. Fifty-three plots with planted saplings of Norway spruce and sycamore maple and 50 plots with dominant naturally regenerated saplings were selected in a randomly stratified manner. Sapling characteristics (height, height increment, root collar diameter, free-to-grow score, browsing and micro-site) were assessed in 2012 and 2014. Herbs and seedling establishment were studied in two subplots within each plot. Average seedling density was 13,074 and 14,674 ha −1 four and six years after the windthrows, respectively. Seedlings were irregularly distributed, which suggests micro-site differences in regeneration dynamics. The results indicated lower seedling success on sites that were southerly exposed, farther from the forest edge and seed trees, on undisturbed micro-sites and at higher altitudes. On such sites planting was justified. While seedling density indicated a positive relation to herb coverage, sapling survival was negatively associated with it as well as with browsing. Initial sapling height was the strongest predictor of survival. Spruce saplings had the lowest mortality, while shade-tolerant silver fir and beech experienced high mortality. The study indicated a high density and species diversity of naturally regenerated seedlings within windthrow areas, which was reduced by planting, mowing of competing vegetation and protection measures favouring planted saplings. Recommendations for the improvement of silvicultural operations for post windthrow restoration are given. [ABSTRACT FROM AUTHOR]

Trees retained during green-tree retention forestry are expected to function as biological legacies that promote biodiversity and enhance ecosystem functions in plantation forests. Investigating how historically retained trees function as biological legacies could help predict the long-term ecological potential of current retention practices. Here, we investigated whether large, retained trees of Cryptomeria japonica D. Don (>1000 years old) functioned as refugia for persistence of canopy woody plants after logging in a 350-year-old secondary forest in Yakushima, southern Japan. We climbed five each of retained and regenerated trees in a 1-ha research plot, measured trunk and crown structures, and tagged and measured every woody plant stem found on each tree. Compared to regenerated trees, retained trees had twice the surface area available for canopy plant colonization. Moreover, retained trees hosted disproportionately greater abundance of canopy woody plants. Together, the five retained trees hosted 22 species of woody plants comprising 1188 individuals, whereas regenerated trees hosted only 8 species (37 individuals). Combined with our ground-based measurement, canopy woody species contributed 16% of all woody plant species in the plot. Among the five retained trees, woody plant abundance increased markedly with increasing age of trunk breaks. This was because numerous epicormic branches had sprouted below trunk breaks creating large surface area upon which arboreal soil accumulated and woody plants established. Canopy woody plants on retained trees showed wide vertical distribution corresponding to complex crown structure, whereas those on regenerated trees occurred almost exclusively on the lower trunk. Maximum stem size of canopy woody plants was constrained by the volume of arboreal soil upon which they grew. Based on their size structures, we inferred that three species endemic to Yakushima ( Vaccinium yakushimense Makino., Viburnum urceolatum Sieb. et Zucc., and Rhododendron yakushimanum Nakai) , maintain stable populations in the retained trees by sprouting. Several other species scarcely found on the ground were also regenerating in the canopy. Our results demonstrate that retained trees of Cryptomeria functioned as refugia allowing canopy woody plants to persist after logging and give support to the importance of conserving large trees for enhancing biodiversity in forests where canopy plants contribute to species diversity. [ABSTRACT FROM AUTHOR]

Warming-induced mortality and a decline in regeneration potential have recently been observed in semiarid forests. To understand future forest dynamics, studies have begun to examine the long-term resilience of semiarid forests against climate change. Previous research has documented a relatively high resilience through seedling production for patchy coniferous forests at the arid timberline compared to continuous and arid tree line forests. However, it remains unclear whether broad-leaved forests in semiarid regions share the same pattern and how they work. In this study, we observed a similar nonlinear pattern in forest resilience along a local aridity gradient by reconstructing the regeneration history and investigating post-mortality regeneration in white birch-dominated ( Betula platyphylla ) forests in semiarid Inner Asia. Changes in regeneration modes from seedling to sprout production accelerated the white birch regeneration process and speeded up tree replacement. High competition from abundant recruits enhanced both forest resilience and resistance to climate change in arid timberline forests. However, only weak resilience was observed in birch forests at the arid tree line, which stopped regeneration and meant that old trees dominated the age structure. This might increase the risk of hydraulic failure. Our results implied that the decline in regeneration potential was not consistent in semiarid regions. Although forest mortality increased along with aridity, some broad-leaved forests at the arid timberline have a high resilience because they generate abundant sprouts to compensate for the losses from forest mortality. This study shows that a similar resilience pattern occurs under the impact of climate change and that various resilience mechanisms are affected by the different biological features of coniferous and broad-leaved forests in Inner Asia, which have important implications for future forest dynamics in semiarid regions and provide scientific background for managing this vulnerable forest and important insights into persistence of forests in semi-arid Inner Asia. [ABSTRACT FROM AUTHOR]

In disturbance-dependent forest ecosystems, species associated with mature forest may maintain their ranges both by persisting in patches of mature forest and by recolonising patches regenerating after fire, harvesting or other disturbances. The null hypotheses are that these processes are both independent of the intensity of disturbance in the landscape surrounding those patches. These were tested in a 1120 km 2 region of tall, wet eucalypt forest in southern Tasmania, which provides a landscape-scale gradient in disturbance intensity shaped by past wildfires and post-European land-use. For all 50 × 50 m cells in the region, a Landscape Disturbance Intensity (LDI) index was calculated based on the vegetation in the surrounding 0.5, 1.0 and 2.0 km-radius landscapes. The occurrence of species in three taxonomic groups – birds, vascular plants and flighted beetles – was then sampled in 28 plots (50 × 50 m) across the range of LDI in each of two forest age-classes – mature eucalypt forest (MAT) and 25–50 years-old silvicultural regeneration arising from clearfell harvesting (SILV). In both MAT and SILV plots, the occurrences of many common species showed significant relationships with LDI. Most (>80%) of those relationships reflected species that declined in occurrence with increasing LDI, i.e. were Landscape Disturbance-Sensitive (DS L ). However, there were contrasting patterns between the forest age-classes as well as among the three taxonomic groups in the proportion of common species that were DS L . More plant and bird species were DS L in SILV plots (15/49 and 9/27, respectively) than in MAT plots (4/49 and 1/27, respectively). The dominant fractions of the DS L plant and bird species in SILV plots were classed as rainforest trees or shrubs in previous studies and birds that were associated with MAT plots rather than SILV plots in this study, i.e. species that were also sensitive to disturbance at the patch-scale. A similar number of the common beetle species were DS L in MAT plots (29/234) as in SILV plots (35/234). Beetle species that were Patch Disturbance-Sensitive (DS P) in this study were over-represented in the subset of DS L species in MAT plots (9/29), but not in SILV plots (5/35). We conclude that many DS P species inhabiting mature forest stands are resilient to disturbance in the surrounding landscape, but their ability to recolonise regenerating forest stands can be diminished by disturbance at the landscape-scale. This highlights the role of vegetation structure at both patch and landscape-scales in the long-term viability of mature-forest-dependent species in production-forest landscapes. [ABSTRACT FROM AUTHOR]

Abstract: Studies on the ecological impacts of non‐timber forest products (NTFP) harvest reveal that plants are often more resilient to fruit and seed harvest than to bark and root harvest. Several studies indicate that sustainable fruit harvesting limits can be set very high (>80% fruit harvesting intensity). For species with clonal and sexual reproduction, understanding how fruit harvest affects clonal reproduction can shed light on the genetic risks and sustainability of NTFP harvest. We studied 18 populations of a gallery forest tree, Pentadesma butyracea (Clusiaceae), to test the impact of fruits harvest, climate and habitat size (gallery forest width) on the frequency of sexual or clonal recruitment in Benin, West Africa. We sampled populations in two ecological regions (Sudanian and Sudano‐Guinean) and in each region, we selected sites with low, moderate and high fruit harvesting intensities. These populations were selected in gallery forests with varying width to sample the natural variation in P. butyracea habitat size. Heavily harvested populations produced significantly less seedlings but had the highest density and proportion of clonal offspring. Our study suggests that for plant species with dual reproductive strategy (via seeds and clonal), fruit harvesting and associated disturbances that come with it can lead to an increase in the proportion of clonal offspring. This raises the issue that excessive fruit harvest by increasing the proportion of clonal offspring to the detriment of seed originated offspring may lead to a reduction in genetic diversity with consequence on harvested species capability to withstand environmental stochasticity. [ABSTRACT FROM AUTHOR]

In Latvia, the noble broad-leaved tree species woodland with pedunculate oak (Quercus robur L.), small-leaved lime (Tilia cordata Mill.), Norway maple (Acer platanoides L.), wych elm (Ulmus glabra Huds.), white elm (Ulmus laevis Pall.) and common ash (Fraxinus excelsior L.) has decreased to about 1% due to the historical legacy of wood extraction and conversion of fertile soil to agricultural land-use. The aim of the current study was to determine the tree age structure in the canopy and size structure in the shrub layer of broad-leaved tree stands to determine past changes and to predict future trends in tree species composition in the context of potential management methods. In 50 randomly selected broad-leaved tree stands, plots of size 0.1 ha were established. In the plots, diameter at breast height was measured for all trees with diameter >10 cm and cores were removed from all of these trees. All other stems were counted by species in height classes ≤ 1 m, 1.1 to 5 m, 5 to 10 m. The stands were classified into 10 groups based on canopy composition in age classes. Norway spruce [Picea abies (L.) H. Karst.] was common in various tree layers of in many of the groups, and it is recommended that it should be removed during stand tending. Q. robur regeneration should be promoted in specific cases where abundant in the < 1 m layer and where large gaps can be created. T. cordata is commonly present in several tree layers and its growth could be promoted by thinning of P. abies where present. Abundant Q. robur regeneration is sometimes found in Scots pine (Pinus sylvestris L.) stands. [ABSTRACT FROM AUTHOR]

Accurate inference of relatedness between individuals in breeding population contributes to the precision of genetic parameter estimates, effectiveness of inbreeding management and the amount of genetic progress delivered from breeding programs. Pedigree reconstruction has been proven to be an efficient tool to correct pedigree errors and recover hidden relatedness in open pollinated progeny tests but the method can be limited by the lack of parental genotypes and the high proportion of alien pollen from outside the breeding population. Our study investigates the efficiency of sib-ship reconstruction in an advanced breeding population of Eucalyptus nitens with only partially tracked pedigree. The sib-ship reconstruction allowed the identification of selfs (4% of the sample) and the exploration of their potential effect on inbreeding depression in the traits studied. We detected signs of inbreeding depression in diameter at breast height and growth strain while no indications were observed in wood density, wood stiffness and tangential air-dry shrinkage. After the application of a corrected sib-ship relationship matrix, additive genetic variance and heritability were observed to increase where signs of inbreeding depression were initially detected. Conversely, the same genetic parameters for traits that appeared to be free of inbreeding depression decreased in size. It therefore appeared that greater genetic variance may be due, at least in part, to contributions from inbreeding in these studied populations rather than a removal of inbreeding as is traditionally thought. [ABSTRACT FROM AUTHOR]

Reversing large-scale degradation and deforestation goes beyond what can be achieved by site-level ecological restoration. Forest and landscape restoration focuses on spatial scales beyond the 'site' level, where multiple land uses and forms of land ownership coexist, and where management decisions are usually made by different sets of stakeholders. In this context, natural regeneration can be a cost-effective approach to expand buffer zones of protected areas or forest reserves, create new forest patches and riparian zones, and create biological corridors to link existing protected areas. Here, I describe different modalities of natural regeneration, describe their benefits and features, and present several case studies of large-scale natural regeneration. Regrowing forests are often ignored, and their ecological and economic value remains largely unrecognized. Effective incentives for landowners and local communities are needed to encourage and protect naturally regenerating forests on farms. Predicting and mapping areas with a high capacity for natural regeneration will lower the overall costs of implementing restoration at local, regional, and national levels and may permit larger areas to be restored. Regrowing tropical forests will play an increasingly important role in climate change mitigation and biodiversity conservation in our future uncertain world. [ABSTRACT FROM AUTHOR]

Trees commonly reproduce via masting cycles, which involves synchronized inter-annual variability in fruit crop size. A few individuals in a population will commonly produce much more fruit than others. If these trees produce fruit more frequently, as indicated by a lower inter-annual variability in fruit production, they may dominate fruit production over time., By measuring fruit production of 1635 individuals of 10 temperate tree species across 4 years in northern lower Michigan, we estimated the inter-annual variability and synchrony in each species. We compared fruit production estimates with measurements of tree size, soil nutrient availability and neighbourhood crowding to investigate the source of inter-individual variation in number of fruit produced., We found that trees' fruit production increased with tree size. The trees that accounted for the largest proportion of total fruit production had lower inter-annual variability and higher synchrony in fruit production. These 'super-producer' trees tended to have high nutrient availability and few neighbouring trees, but there were no effects of nutrient availability or neighbourhood crowding on fruit production in the population as a whole., Synthesis. Masting is a population-level phenomenon, and is typically studied at this level. However, when we apply individual tree observations of fruit production to this phenomenon, it reveals super-producers which produce fruit more consistently than the rest of the population. By reducing inter-annual variability in fruit production, but increasing synchrony and making large numbers of fruit, super-producers may be able to reap the benefits of masting while governing population fruit production over time. [ABSTRACT FROM AUTHOR]

Timber management directly influences the population dynamics of tree species, like Copaifera spp. (copaíba), which provide oil-resin with ecological and economic importance. The aim of this study was to evaluate the structure and population dynamics of Copaifera in unmanaged and managed stands by reduced-impact logging (RIL) in eastern Amazon in Pará state, Brazil. Based on a stem map of the study area, 40 Copaifera trees were randomly selected, where an equal number of trees were selected in managed and unmanaged stands. A transect of 10 Χ100 m was centered at each tree (50 m each side) to assess Copaifera regeneration. Transects were subdivided into ten plots, of which six were systematically chosen to assess the height, diameter and number of Copaifera seedlings and saplings. The field assessment occurred in 2011 and 2013. To estimate the amount of sunlight transmitted to the forest floor, we computed canopy cover from airborne LiDAR data. According to the results, the abundance of Copaifera seedlings/saplings was higher in managed than unmanaged stands. About 5% of Copaifera regeneration was found between 45–50 m from the Copaifera tree while ~73% of regeneration was concentrated within a 10 m radius of the Copaifera tree. We verified that the diameter distribution of Copaifera regeneration was not a negative exponential distribution, as is typical of most tree species in natural forest. Rather, the Copaifera regeneration had a spatially aggregated distribution. In this short-term analysis, the impact of timber management is not negatively affecting the population structure or dynamics of Copaifera regeneration. [ABSTRACT FROM AUTHOR]

The success of some invasive tree species is attributed, in part, to high fecundity in the form of sexual propagules. If invasive trees produce more seed annually than co-occurring native trees, they will have a greater ability to disperse and establish across the landscape. In this study, seed production of female Ailanthus trees was investigated to determine (1) reproductive age limits; (2) annual and cumulative seed output; and (3) seed viability. Existing data on Ailanthus seed production were combined with a novel dataset to compare variability in seed production and explore relationships with tree diameter and age. Results from this study showed Ailanthus’ reproductive window is exceptional, spanning more than a century, with seed viability exceeding 65% from a 104-year-old individual. Germination studies and complementary tetrazolium assays also confirmed high propagule viability from a 7-year-old Ailanthus and supports tetrazolium assays as a proxy for germination studies. Not only can individual Ailanthus produce >1 million seeds annually, but a significant relationship exists between seed production and tree diameter. Using this relationship, cumulative seed production in individual Ailanthus can reach ca. 10 and 52 million seeds over a 40-year and 100-year period, respectively. This study provides a comprehensive investigation of various facets of the reproductive potential of Ailanthus. [ABSTRACT FROM AUTHOR]

A comparative investigation of growth and reproductive parameters of trees of the cherry cultivars Kozerska, Stella and Stefania with five different cutting heights of the stem and summer pruning was conducted during the period 2008-2014. The cultivars were grafted on mahaleb rootstock and planted at a spacing of 5 x 5 m. The growth of the trees of all cultivars was most vigorous at heights of the stems of 70 and 110 cm. The application of summer pruning led to suppression of the growth, which was with the lowest value among the treatments tested. During the period of full fruit-bearing, the highest fruit yields and largest fruits were obtained in the treatments with trees whose stems were shortened at 70 and 110 cm above the soil surface. Summer pruning and cutting of the stems at 25 cm above the soil surface retarded the transition of the trees into full fruit-bearing. Cultivar Stella shortened to 70 cm had the best economic performance (1,534 euro/ha), followed by Stefania at 110 cm (1,498 euro/ha); the lowest values of this parameter were observed in Kozerska at a stem height of 70 cm and summer pruning applied (264 euro/ha). Stella and Stefania had better growth and economic properties than Kozerska. [ABSTRACT FROM AUTHOR]

In the boreal forest, long-lasting canopy gaps are associated with lichens on dry sites and with Sphagnum spp. on wet sites. We hypothesize that ground-layer composition plays a role in maintaining gaps through its effects on fine root biomass (diameter ≤ 2 mm) and soil nutrient availability. Along gradients of canopy openness in both jack pine ( Pinus banksiana Lamb.) - lichen and black spruce ( Picea mariana (Mill.) B.S.P.) - moss forests, the relationships between canopy closure, ground-layer composition, tree fine root biomass, and soil nutrients were analyzed and decomposed using path analysis. The effects of lichen and Sphagnum spp. removal on tree fine root biomass and soil nutrients were tested in situ. Although variations in pine fine root biomass were mainly explained by stand aboveground biomass, lichen removal locally increased fine root biomass by more than 50%, resin extractable soil potassium by 580%, and base cations by 180%. While Sphagnum cover was identified as a key driver of stand aboveground biomass reduction in paludified forest sites, its removal had no short-term effects on spruce fine root biomass and soil nutrients. Our results suggest that lichens, more than Sphagnum spp., affect tree growth via direct effects on soil nutrients. These two different patterns call for different silvicultural solutions to maintain productive stands. [ABSTRACT FROM AUTHOR]

Stand dynamics were monitored for 10 years after conventional logging (CL), reduced-impact logging (RIL) and RIL followed by enrichment line planting (LP) and annual slashing (S) (RIL + LP/S) in three 1-ha plots in each of the three sites of a lowland dipterocarp forest in Central Kalimantan. All trees with diameter at breast height (DBH) >10 cm and planted Shorea johorensis were monitored for survival and growth. Natural recruitment poles of commercial Shorea sp. (DBH > 10 cm) were very low in CL site, intermediate in RIL and high (46 ± 29.5 trees ha-1) in RIL + LP/S. Ten years after treatment, 78% of the planted seedlings were still alive. Although LP increased the stock of desirable Shorea sp. relative to RIL, the improvement of light conditions caused by strip cutting and slashing significantly promoted natural regeneration. For sustainable forest production, LP/S are appropriate treatments. From a financial perspective, LP is recommended when reintroducing desirable species. Selection of the appropriate silvicultural treatment will depend on the post-logging state of the forest and the relative cost of LP and S. [ABSTRACT FROM AUTHOR]

Global change is generating widespread local-scale expansions of tree populations. During demographic expansions, even small differences in individual reproductive success can generate large differences in the genetic composition of the resulting population. Colonizing tree populations almost invariably show highly skewed distributions of seed production, but the evolution of this reproductive skew during plant recruitment remains understudied., We examine how recruit mortality modifies initial patterns of acorn dispersal and maternal reproductive success in a recently established, expanding Pedunculate oak ( Quercus robur) forest stand and test different predictors of successful recruit establishment., We mapped and genotyped a cohort of seedlings ( n = 809) emerging within and around the stand ( n = 254 adult trees), identified their habitats and monitored their fate until an age of 3 years. Their mother trees were inferred by Bayesian parentage analysis, and the number of assigned descendants was used as a proxy for tree maternal fertility. We examined temporal trends in tree fertility and patterns of dispersal, and tested effects of seed number-quality trade-offs, dispersal failure, dispersal distance and habitat of propagule arrival on the probability of seedling establishment., We observed marked inequality in maternal reproductive success at the time of seedling emergence. A positive relationship between tree fertility and the proportion of non-dispersed seedlings pointed to disperser satiation. An overall seedling mortality of 69% generated considerable reshuffling in the fertility ranking of individual trees. Non-dispersal more than doubled seedling mortality. The establishment success of actually dispersed seedlings was independent of mother fertility and dispersal distance but strongly related to the habitat of arrival. Recruit survival was markedly higher in pine plantations or non-forested areas than in broadleaved forest., Synthesis. A few highly fertile trees dominated reproduction in the stand. Differential recruitment success tended to reduce their initial advantage, however, suggesting that reproductive inequality might rapidly decline as more trees start to reproduce along the expansion process. Our results also suggest that field estimates of size or seed production are unlikely to provide reliable estimates of lifetime reproductive success in trees. [ABSTRACT FROM AUTHOR]

The severity and spatial extent of bark-beetle outbreaks substantially increased in recent decades worldwide. The ongoing controversy about natural forest recovery after these outbreaks highlights the need for individual-based long-term studies, which disentangle processes driving forest regeneration. However, such studies have been lacking. To fill this gap, we followed the fates of 2,552 individual seedlings for 12 years after a large-scale bark-beetle outbreak that caused complete canopy dieback in mountain Norway spruce ( Picea abies) forests in southeast Germany. We explore the contribution of advance, disturbance-related, and post-disturbance regeneration to forest recovery. Most seedlings originated directly within the three-year dieback of canopy trees induced by bark-beetle outbreak. After complete canopy dieback, the establishment of new seedlings was minimal. Surprisingly, advance regeneration formed only a minor part of all regeneration. However, because it had the highest survival rate, its importance increased over time. The most important factor influencing the survival of seedlings after disturbance was their height. Survival was further modified by microsite: seedlings established on dead wood survived best, whereas almost all seedlings surrounded by graminoids died. For 5 cm tall seedlings, annual mortality ranged from 20 to 50% according to the rooting microsite. However, for seedlings taller than 50 cm, annual mortality was below 5% at all microsites. While microsite modified seedling mortality, it did not affect seedling height growth. A model of regeneration dynamics based on short-term observations accurately predicts regeneration height growth, but substantially underestimates mortality rate, thus predicting more surviving seedlings than were observed. We found that P. abies forests were able to regenerate naturally even after severe bark-beetle outbreaks owing to advance and particularly disturbance-related regeneration. This, together with microsite-specific mortality, yields structurally and spatially diverse forests. Our study thus highlights the so far unrecognized importance of disturbance-related regeneration for stand recovery after bark-beetle outbreaks. [ABSTRACT FROM AUTHOR]

Joshua trees ( Yucca brevifolia) produce large, indehiscent fruits that contain numerous large seeds. Seed dispersal in this species depends on rodents to dismantle fruits and extract the seeds which they disperse tens of meters from the source. Using camera trapping and fruits tied to bobbins, I show that white-tailed antelope squirrels ( Ammospermophilus leucurus) and kangaroo rats ( Dipodomys spp.) moved intact, fallen fruits 6 to 7 m from trees before opening them. Pocket mice ( Chaetodipus fallax and Perognathus longimembris) and pinyon mice ( Peromyscus trueii) dismantled fruits and harvested loose seeds but did not appear to move them although they readily harvested loose seeds. Mobilizing fruits may be an important, overlooked step in the seed dispersal process, especially if the fruits are indehiscent. Fruit-carrying behavior of rodents described in this study adds to the dispersal distance of Joshua tree seeds. [ABSTRACT FROM AUTHOR]

The present investigation aimed to study the regeneration status of tree species and survival of naturally emerged seedlings along an altitudinal gradient in a protected area of Western Himalaya, India. A total of 44 tree species of 36 genera and 25 families were recorded from the study area. Regeneration status of species was determined based on population size of seedlings and saplings while seedling survival was determined by silver foil tagging method. Seedling density and Shannon-Wiener diversity index (H) ranged from 1670 to 7485 ind ha-1 and 1.91 to 3.32, respectively, while sapling density and Shannon-Wiener diversity index (H) varied from 1850 to 5600 ind ha-1 and 1.23 to 2.57 respectively. Although the majority (27 - 56 %) of species showed good regeneration, a good percentage (19 - 45 %) of tree species showed poor regeneration while fair regeneration was shown by 7 - 30 % of species and new regeneration by 0 - 14 %. Diameter density distribution showed that lower diameter classes have the highest frequency with a gradual decrease in the number of individuals in the higher classes resulting in the formation of an inverse-J curve that is considered to be an indication of good regeneration status. Survival of seedlings in different forests varied from 0 - 88 % (mortality varied from 12 - 100 %). Natural calamities and anthropogenic disturbances are responsible for the high mortality of seedlings. A few species showed discontinuous regeneration due to which it is expected that these tree species although dominant at present may be at risk in future. [ABSTRACT FROM AUTHOR]

The contribution of new photo-assimilates and stored carbon (C) to plant growth remains poorly understood, especially during reproduction. In order to elucidate how mast seeding affects C allocation to both reproductive and vegetative tissues, we measured biomass increase in each tissue, branch starch concentration and stable C isotope composition (δ13C) in bulk leaves, current-year shoots, 3-year branches and tree rings in fruiting and non-fruiting trees for 2 years, as well as in fruits. We isolated the effect of reproduction on C allocation to vegetative growth by comparing 13C enrichment in woody tissues in fruiting and nonfruiting specimens. Compared with 2‰ 13C enrichment in shoots relative to leaves from non-fruiting trees, fruiting reduced the enrichment to 1‰ and this reduction disappeared in the following year with no fruiting, indicating that new photo-assimilates are preferentially used for woody tissues even with fruiting burden. In contrast, fruits had up to 2.5‰ 13C enrichment at midsummer, which dropped thereafter, indicating that fruit production relies on C storage early in the growing season then shifts to current photo-assimilates. At this tipping point, growth of shoots and cupules had almost finished and nuts had a second rapid growth period thereafter. Together with shorter shoots but higher biomass increment per length in fruiting trees than nonfruiting trees, these results indicate that the C limitation due to fruit burden is minimized by fine-tuning of allocation of old C stores and new photo-assimilates, along with the growth pattern in various tissues. Furthermore, fruiting had no significant effect on starch concentration in 3-year-old branches, which became fully depleted during leaf and flower flushing but were quickly replenished. These results indicate that reproduction affects C allocation to branches but not its source or storage. These reproduction-related variations in the fate of C have implications for evaluating forest ecosystem C cycles during climate change. [ABSTRACT FROM AUTHOR]

Species homogenization or floristic differentiation are two possible consequences of the fragmentation process in plant communities. Despite the few studies, it seems clear that fragments with low forest cover inserted in anthropogenic matrices are more likely to experience floristic homogenization. However, the homogenization process has two other components, genetic and functional, which have not been investigated. The purpose of this study was to verify whether there was homogenization of tree reproductive functions in a fragmented landscape and, if found, to determine how the process was influenced by landscape composition. The study was conducted in eight fragments in southwest Brazil. The study was conducted in eight fragments in southwestern Brazil. In each fragment, all individual trees were sampled that had a diameter at breast height ≥3 cm, in ten plots (0.2 ha) and, classified within 26 reproductive functional types (RFTs). The process of functional homogenization was evaluated using additive partitioning of diversity. Additionally, the effect of landscape composition on functional diversity and on the number of individuals within each RFT was evaluated using a generalized linear mixed model. appeared to be in a process of functional homogenization (dominance of RFTs, alpha diversity lower than expected by chance and and low beta diversity). More than 50% of the RFTs and the functional diversity were affected by the landscape parameters. In general, the percentage of forest cover has a positive effect on RFTs while the percentage of coffee matrix has a negative one. The process of functional homogenization has serious consequences for biodiversity conservation because some functions may disappear that, in the long term, would threaten the fragments. This study contributes to a better understanding of how landscape changes affect the functional diversity, abundance of individuals in RFTs and the process of functional homogenization, as well as how to manage fragmented landscapes. [ABSTRACT FROM AUTHOR]

We performed a forest inventory in a fragment of stricto sensu Cerrado to evaluate alpha and beta temporal diversity among adult and natural regeneration (NR) strata. Fifteen plots of 1,000 m² (20 x 50 m) were set to sample the adult stratum, and each plot divided in sub-plots of 100 m² (2 x 50 m) to sample NR. We registered the qualitative (species) and quantitative (height and diameter) floristic composition. Natural Regeneration stratum was divided into three diameter classes (I, II and III). Moreover, species collected on non-oriented paths were registered. We estimated alpha diversity through Shannon index (H'), Pielou index (J') and "one-step" jackknife estimator. Sørensen (Sø -- qualitative) and Czekanowski (SC -- quantitative) indexes were used to evaluate beta diversity. In total, 101 species distributed in 71 genera and 36 families were recorded. For the adult and NR strata, H' values were 3.06 and 3.14 nats per individual, and J' 0.75 and 0.71, respectively. Both strata had qualitative similarity. Natural regeneration showed no similarity with adult stratum by Czekanowski index, although this distance tends to decline with the progressive size of each class. The temporal beta diversity is low between these strata; and there is a trend of increasing similarity with the maturity of NR. [ABSTRACT FROM AUTHOR]

This work presents the tree and shrub species found in Plovdiv Municipality during inventory of ornamental plants implemented in the period 2006-2013. We have identified 393 species of trees and shrubs, most of them (61%) of foreign origin. The paper also includes the observations made by the authors on the ability of the identified species to reproduce by seed or vegetatively, without human help. [ABSTRACT FROM AUTHOR]

The December 2010 forest fire on Mount Carmel - the largest recorded in Israel - burned about 2500 ha of Mediterranean forest. We documented the immediate and short-term changes of the vegetation following this fire. Relative vegetation cover and plant species richness were sampled in five sites in spring 2009 and 2010, prior to the fire, and were re-sampled in 2011 and 2012. The number of recurrent fires (between 0 and 3) and time intervals between fires were documented for each site. We observed a strong decrease in total vegetation cover, associated with reduction of relative cover of woody vegetation. In the second year after the fire, shrubs and dwarf shrubs became dominant at all sites. Time intervals between fires played an important role in determining the extent of regeneration of the vegetation cover and plant species richness. Plant species richness immediately decreased after the fire in sites with a short fire interval, while in sites with a long fire interval, plant species richness increased. Relative plant cover was associated with the time from the last previous fire, and this association differed among different plant groups. These results suggest that vegetation and plant community regeneration after recurrent fires is accelerated when time intervals between fires are longer, whereas high fire frequency may suppress vegetation regeneration. Based on the results, we propose that forest regeneration after recurrent fires depends largely on time from the previous fire, rather than on the number of previous fires. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Variation in tree reproduction can alter forest community dynamics, especially if reproductive output is costly for other functions like growth. However, empirical studies reach conflicting conclusions about the constraints on reproductive allocation relative to growth and how they vary through time, across species, and between environments. Here, we test the hypothesis that a critical resource, canopy exposure to light availability, limits reproductive allocation by comparing long-term relationships between reproduction and growth for trees from 21 species in forests throughout the Southeastern United States. We found that species have divergent responses to light availability, with shade-intolerant species experiencing an alleviation of trade-offs at high light- and shade-tolerant species showing no changes in reproductive output across light environments. Correlations between temporal variation in individual growth and reproduction were weak and generally insensitive to canopy exposure, but changed when considering time lags. The diversity of responses across species indicates that reproductive allocation for trees in these forests is strongly influenced by both species' life history and environmental heterogeneity in space and time. [ABSTRACT FROM AUTHOR]

Forest and woodland ecosystems may be strongly affected by climate change influences on tree population processes such as seed production and seedling recruitment. Yet climate effects on seed production are generally poorly understood, particularly for trees that exhibit masting behavior (i.e. high synchronicity and high inter-annual variability in seed production). This is largely due to the limited amount of long-term datasets on seed production, which are necessary to characterize the highly variable reproductive outputs of masting species. The cone abscission scar method provides a promising approach to accurately determine historical (past 10–20 years) annual cone production, but the method has not been rigorously validated. Here we use a long-term dataset of cone abundance on individually monitored pinyon pine ( Pinus edulis ) trees to validate the cone abscission scar methodology. Tree cone production estimated using abscission scars was positively associated with observed mature cone and conelet abundances from 8 to 13 years previously (Spearman’s ρ = 0.52 and 0.66, respectively), the time period of our observed historical cone production data. Further, we show that between 4–5 branches per tree and 4–6 trees per site need to be sampled to minimize the variance in cone abundance estimates. Thus, only approximately 3–4 h are needed to obtain an estimate of historical annual cone production in a stand. Overall, we show that the cone abscission scar method provides a robust and time efficient approach to accurately determine historical annual cone production for P. edulis and likely other slow-growing conifer trees. [ABSTRACT FROM AUTHOR]