Woodland Restoration Research Articles

Building alliances and consensus around social-ecological rewilding in Chile

We provide a case study of how we position our rewilding project in central Chile in order to find scientific and social support and build alliances, collaborations, and consensus. Our core vision focuses on reintroducing guanacos (Lama guanicoe) to central Chile in order to provide natural restoration and ecosystem processes in espinal woodlands dominated by the native tree Vachellia [Acacia] caven. We envision a scenario of “social-ecological rewilding” with widespread guanaco browsing in woodlands and guanaco migration across the region, coexisting with multiple human uses of the landscape. Guanacos would ideally be managed by regional collectives who could benefit from guanaco tourism, sustainable harvest of their fiber (wool), and regulated hunting. Our wider vision for reintroductions and integrated conservation management extends to a set of other species that may have coexisted with guanacos and V. caven at various points in the past, but more research is necessary to establish and gain support for evidence-based baselines. Our strategy is to inspire actors with greater resources (land, money, influence) to share our vision and implement it, in collaboration with the NGO that we have formed to support our projects. Over ten years, circulating alternate interpretations and a novel imaginary of how central Chile was in the past and could be in the future, along with developing and testing scientific hypotheses, has moved our vision from an idea shared by two people to one that a wide variety of actors publicly embrace.

Sounds of the underground reflect soil biodiversity dynamics across a grassy woodland restoration chronosequence

Abstract Restoring and monitoring soil biodiversity has never been more important. Ecoacoustics is emerging as a promising tool to detect and monitor soil biodiversity and was recently effective in a temperate forest context. However, there is a need to investigate the efficacy of soil ecoacoustics in other ecosystems and bioregions. Here, we applied ecoacoustics tools and indices (Acoustic Complexity Index, Bioacoustic Index, Normalised Difference Soundscape Index) to measure soil biodiversity in an Australian grassy woodland restoration chronosequence, spanning three age classes. We collected n = 240 soil acoustic samples from two cleared plots (continuously cleared through active management), two woodland plots undergoing restoration (revegetated 14–15 years ago) and two plots of remnant vegetation over 5 days in Mount Bold, South Australia. We used a below‐ground sampling device and sound attenuation chamber to record soil invertebrate communities, which were also manually counted. We found that acoustic complexity and diversity were significantly higher in revegetated and remnant plots than in cleared plots, both in‐situ and in sound attenuation chambers. The acoustic complexity and diversity also significantly associated with soil invertebrate abundance and richness. Synthesis and applications. Our results provide new support that ecoacoustics can help monitor soil biodiversity in different forest restoration contexts, including in UK temperate and Australian grassy woodlands. This technology holds promise in addressing the global need for effective soil biodiversity monitoring methods and protecting our planet's most diverse ecosystems.

Fire effects on plant communities in Ozark woodlands and glades

BackgroundDecades of fire suppression caused drastic changes to community structure and composition across ecosystems, including in Ozark woodlands in Missouri, USA. Reintroducing fire can restore ground flora by reducing midstory tree density, increasing ground layer light, and reducing leaf litter accumulation, but we lack a clear understanding of how these effects vary across time and space. We investigated the effects of repeated prescribed fire on ground flora species richness, floristic quality, abundance, community composition, and stand structure over 20 years in a landscape matrix of dry-mesic woodlands, dry woodlands, and glades using data collected from the Ozark National Scenic Riverways Fire Effects Monitoring program in the Current River Watershed in the Missouri Ozarks.ResultsWe found that fire plays a key role in driving community structure and dynamics across community types, although with varying levels of intensity. Herbaceous species richness, abundance, and floristic quality index increased across all community types, while mean coefficient of conservatism decreased. Abundance and floristic quality effects were stronger in drier sites. Community composition changed with successive burns, resulting in several indicator species for post burn treatments. The density of midstory trees declined across community types with repeated fire. The number of burns significantly affected overstory tree density overall, but overstory tree density only declined in dry woodlands and glades and not in dry-mesic woodlands.ConclusionsOur results suggest that landscape fire shapes plant community structure and dynamics. Specifically, these findings show that fire effects vary among community types and suggest that land managers should consider landscape heterogeneity in fire application for restoration. Separate community types imbedded in the same landscape may respond to fire differently. Understanding repeated fire effects over several decades across multiple community types is critical to informing fire-driven woodland restoration across landscape scales.

Complex and highly saturated soundscapes in restored oak woodlands reflect avian richness and abundance.

Temperate woodlands are biodiverse natural communities threatened by land use change and fire suppression. Excluding historic disturbance regimes of periodic groundfires from woodlands causes degradation, resulting from changes in the plant community and subsequent biodiversity loss. Restoration, through prescribed fire and tree thinning, can reverse biodiversity losses, however, because the diversity of woodland species spans many taxa, efficiently quantifying biodiversity can be challenging. We assessed whether soundscapes in an eastern North American woodland reflect biodiversity changes during restoration measured in a concurrent multitrophic field study. In five restored and five degraded woodland sites in Wisconsin, USA, we sampled vegetation, measured arthropod biomass, conducted bird surveys, and recorded soundscapes for five days of every 15-day period from May to August 2022. We calculated two complementary acoustic indices: Soundscape Saturation, which focuses on all acoustically active species, and Acoustic Complexity Index (ACI), which was developed to study vocalizing birds. We used generalized additive models to predict both indices based on Julian date, time of day, and level of habitat degradation. We found that restored woodlands had higher arthropod biomass, and higher richness and abundance of breeding birds. Additionally, soundscapes in restored sites had higher mean Soundscape Saturation and higher mean ACI. Restored woodland acoustic indices exhibited greater magnitudes of daily and seasonal peaks. We conclude that woodland restoration results in higher soundscape saturation and complexity, due to greater richness and abundance of vocalizing animals. This bioacoustic signature of restoration offers a promising monitoring tool for efficiently documenting differences in woodland biodiversity.

Floristic Diversity and Natural Regeneration of Miombo Woodlands in the Rural Area of Lubumbashi, D.R. Congo

Increased anthropogenic pressure on forest resources leads to deforestation and forest degradation, significantly limiting the regeneration capacity of native woody species and consequently the restoration of miombo woodlands in anthropized habitats within the rural area of Lubumbashi. This study assessed miombo species’ diversity and natural regeneration capacity through floristic inventories in three different habitats (unexploited forests, degraded forests, and post-cultivation fallows). The results reveal that for the adult stratum, unexploited and degraded forests exhibit higher dendrometric (density, mean square diameter, basal area) and floristic parameter (taxa, genera, families) values compared to post-cultivation fallows. Furthermore, the regeneration of miombo woody species is higher in degraded forests (21 taxa; 105 juveniles/plot). However, regarding the sapling’s stratum (1 cm ≤ dbh < 10 cm), the three habitats display similar situations. Additionally, the floristic composition and diversity of unexploited and degraded forests show a significantly higher similarity (76.50%) among them compared to these habitats and the post-cultivation fallows (56.00%). These findings indicate that miombo woodlands have the potential to regenerate and maintain floristic diversity even in anthropized habitats, particularly in degraded forests. To sustain this natural regeneration capacity of miombo woody species and promote the restoration of forest cover and its floristic diversity, it is imperative to determine the rotation period after habitat exploitation and regulate anthropogenic activities and late bush fires, particularly in anthropized habitats at the village level.

Comparing grass biomass estimation methods for management decisions in a semi‐arid landscape

AbstractAimsEnvironmental managers require reliable and cost‐efficient monitoring methods for effective decision‐making. Understanding forage availability is important for managing wild, vertebrate herbivore populations. We developed a process for exploring the accuracy and cost efficiency of various biomass estimation techniques for a case study where semi‐arid woodland restoration is threatened by kangaroo grazing, with the aim of determining which method was most fit for purpose in a given decision context.LocationWyperfeld National Park, southeastern Australia.MethodsGrass biomass was estimated using a variety of methods, then compared to clipped biomass using linear models. Biomass estimation methods were either field‐based (i.e., rising plate meter, multispectral radiometer) or satellite‐based (i.e., Landsat satellite imagery, AussieGRASS forage production model). Sampling occurred across open and wooded semi‐arid vegetation types. We compared methods based on accuracy, the ability of each method to accurately predict a ‘forage‐switch’ threshold, cost, and the suitability for the management context.ResultsFor this case study, the multispectral radiometer was the most precise, yet most expensive, biomass estimation method over a single survey. However, satellite imagery proved to be the most cost‐efficient and fit for purpose, as it was inexpensive and most accurately estimated biomass around a forage‐switch threshold, second only to the multispectral radiometer. Accuracy of all methods was improved by including tree cover in the regression models.ConclusionsWe demonstrate a process for exploring which biomass estimation tool might be preferred for a given decision context, highlighting accuracy, consideration of tolerance to uncertainty and risk, the spatial and temporal scale of information required, and budget constraints.

Site-Level Modelling Comparison of Carbon Capture by Mixed-Species Forest and Woodland Reforestation in Australia

Large areas of Australia’s natural woodlands have been cleared over the last two centuries, and remaining woodlands have experienced degradation from human interventions and anthropogenic climate change. Restoration of woodlands is thus of high priority both for government and society. Revegetation of deforested woodlands is increasingly funded by carbon markets, with accurate predictions of site-level carbon capture an essential step in the decision making to restore. We compared predictions of carbon in above-ground biomass using both the IPCC Tier 2 modelling approach and Australia’s carbon accounting model, FullCAM, to independent validation data from ground-based measurements. The IPCC Tier 2 approach, here referred to as the FastTrack model, was adjusted to simulate carbon capture by mixed-species forests for three planting configurations: direct seeding, tubestock planting, and a mix thereof. For model validation, we collected data on above-ground biomass, crown radius, and canopy cover covering an age range of 9–35 years from 20 plantings (n = 6044 trees). Across the three planting configurations, the FastTrack model showed a bias of 2.4 tC/ha (+4.2% of the observed mean AGB), whilst FullCAM had a bias of −24.6 tC/ha (−42.9% of the observed mean AGB). About two-thirds of the error was partitioned to unsystematic error in FastTrack and about one-quarter in FullCAM, depending on the goodness-of-fit metric assessed. Model bias differed strongly between planting configurations. For the FastTrack model, we found that additional canopy cover data estimated from satellite images obtained at different years can improve the carbon capture projections. To attain the highest accuracy of carbon projection at the site level, we recommend using a model with parameters calibrated for the specific planting configuration using local representative data.

Restoration age affects microbial-herbaceous plant interactions in an oak woodland.

In degraded ecosystems, soil microbial communities (SMCs) may influence the outcomes of ecological restoration. Restoration practices can affect SMCs, though it is unclear how variation in the onset of restoration activities in woodlands affects SMCs, how those SMCs influence the performance of hard-to-establish woodland forbs, and how different woodland forbs shape SMCs. In this study, we quantified soil properties and species abundances in an oak woodland restoration chronosequence (young, intermediate, and old restorations). We measured the growth of three woodland forb species when inoculated with live whole-soil from young, intermediate, or old restorations. We used DNA metabarcoding to characterize SMCs of each inoculum treatment and the soil after conditioning by each plant species. Our goals were to (1) understand how time since the onset of restoration affected soil abiotic properties, plant communities, and SMCs in a restoration chronosequence, (2) test growth responses of three forb species to whole-soil inoculum from restoration sites, and (3) characterize changes in SMCs before and after conditioning by each forb species. Younger restored woodlands had greater fire-sensitive tree species and lower concentrations of soil phosphorous than intermediate or older restored woodlands. Bacterial and fungal soil communities varied significantly among sites. Forbs exhibited the greatest growth in soil from the young restoration. Each forb species developed a unique soil microbial community. Our results highlight how restoration practices affect SMCs, which can in turn affect the growth of hard-to-establish forb species. Our results also highlight that the choice of forb species can alter SMCs, which could have long-term potential consequences for restoration success.

Response of Soil Physicochemical Properties and Microbial Community Composition in Larix olgensis Plantations to Disturbance by a Large Outbreak of Bark Beetle

Forests are affected by a wide range of disturbances globally, resulting in the decline or death of large areas of them. There is a lack of comparative studies on how soil properties change in forests that die under the influence of disturbances, especially considering different levels of disturbance. For this study, we took Larix olgensis—a major plantation forest species in northeast China—as the research object, one in which a large outbreak of bark beetle led to large-scale forest death, and set up fixed sample plots characterized by different disturbance intensities. We investigated the responses of soil physicochemical properties and microbial community compositions to different disturbance intensities through the determination of soil nutrient indices and high-throughput sequencing. The results show that there were significant differences (p < 0.05) in the effects of different disturbance intensities on soil physicochemical properties, where the soil moisture content, total nitrogen, total carbon, and total phosphorus in the control group were significantly higher than those in the disturbed groups. The soil pH was highest under low-intensity disturbance and the soil total potassium content was highest under high-intensity disturbance. At different disturbance intensities, the highest soil moisture content was found in the high-intensity group. Proteobacteria, Actinobacteria, Verrucomicrobia, Acidobacteria, Candidatus_Rokubacteria, Chloroflexi, Gemmatimonadetes, and Thaumarchaeota were the dominant populations with higher abundances; meanwhile, the relative abundance of Bacteroidetes, Tenericutes, and a tentatively unclassified fungus differed significantly (p < 0.05) across disturbance intensities. Among the dominant microbial populations, Acidobacteria showed a significant negative correlation with soil pH and a significant positive correlation with total potassium content, Thaumarchaeota showed significant positive correlations with soil moisture content and total nitrogen content, and Firmicutes and Gemmatimonadetes showed significant negative correlations with total carbon content in the soil. Furthermore, soil total nitrogen content was the key factor driving changes in microbial communities. The results of this study provide a scientific basis for the study of the long-term effects of tree mortality caused by insect pests on soil microbial communities and their response mechanisms, which is of great theoretical value for the establishment of scientific and effective methods for woodland restoration.

Evaluation of field survival and growth to support the restoration of four valuable Miombo tree species

Understanding of right nursery practices is important for the production of high quality seedlings and successful restoration of trees with limited natural regeneration and/or on-farm tree planting. We evaluated the effects of nursery practices on field tree survival and growth in two trials in Morogoro, Tanzania: 1) shading regime, polythene tube size with four Miombo tree species i.e. Albizia harveyi, A. versicolor, Diplorhynchus condylocarpon and Pterocarpus angolensis; and 2) soil mixture and mycorrhizae/rhizobia inoculation with three Miombo tree species i.e. A. versicolor, D. condylocarpon and P. angolensis. There were no significant effects of the shading regime and polythene tube size on the survival, root collar diameter and height for all studied tree species. Almost all P. angolensis trees died after one year but the overall tree survival was good (>80 %) for the other tree species. Tree survival was always higher in nursery soil mixture S5 (0: 0: 1 sand: cow manure: soil) for D. condycarpon and at the early stages for P. angolensis. Mycorrhizae/rhizobia inoculation reduced tree survival of D. condylocarpon but not for other tree species. Interactions of soil mixture and mycorrhizae/rhizobia were only significant for D. condylocarpon and only with soil mixture S6 (1: 2: 3 sand: cow manure: soil). The advantages of medium and large polythene tubes on tree survival and growth in the field are dismissed in favour of small polythene tubes (10 x 10 cm). Nursery forest top soil alone is recommended for P. angolensis and D. condylocarpon. Albizia harveyi and A. versicolor can be grown in any of the soil mixtures tested. Testing the effect of nursery techniques on the field performance of these tree species in dry areas or poor soils, and for enrichment planting is recommended to enhance restoration of Miombo woodland.

Assessing the potential impact of retaining native off‐site tree species in woodland restoration

Reestablishing appropriate tree species is an important step in converting off‐site monocultures into woodlands. Species conversion is often necessary, as off‐site exotic species rarely function like woodland species. However, when off‐site tree species are native, and functionally redundant to woodland species, conversion may be unnecessary. To explore this possibility in the southeastern United States, we reviewed the literature on trait differences among the primary southern pines and qualitatively assessed the effect of their identity at the species and stand‐levels. In this region, woodland restoration focuses on removing loblolly (Pinus taeda) and slash pine (P. elliottii) to reestablish longleaf (P. palustris) or shortleaf pine (P. echinata). Our review found minimal variation among species in understory flammability, fire resistance at maturity, and Red‐cockaded Woodpecker (Leuconotopicus borealis) habitat at the stand‐level. Longleaf and shortleaf pine were generally more resistant to abiotic and pest disturbance at the tree‐level; however, stand‐level differences in wind, drought, and boring insect resistance among southern pines growing in open forests were considered minimal. Retaining loblolly and slash pine will improve stand‐level productivity in the short term, but creates regeneration problems due to low juvenile fire resistance and resilience. Ice resistance and long‐term carbon sequestration will also likely be reduced by retaining loblolly and slash pine. Collectively, these results suggest that southern pine species are generally interchangeable at the stand‐level in woodlands; although woodlands featuring loblolly and slash pine may be less stable in the face of disturbance than those dominated by shortleaf and longleaf pine.

Limited efficacy of a commercial microbial inoculant for improving growth and physiological performance of native plant species.

Soil microbial inoculants are increasingly being explored as means to improve soil conditions to facilitate ecological restoration. In southwestern Western Australia, highly biodiverse Banksia woodland plant communities are increasingly threatened by various factors including climate change, land development and mining. Banksia woodland restoration is necessary to conserve this plant community. The use of microbial inoculation in Banksia woodland restoration has not yet been investigated. Here, we evaluated the efficacy of a commercial microbial inoculant (GOGO Juice, Neutrog Australia Pty Ltd) for improving the performance of 10 ecologically diverse Banksia woodland plant species in a pot experiment. Plants were subjected to one of two watering regimes (well-watered and drought) in combination with microbial inoculation treatments (non-inoculated and inoculated). Plants were maintained under these two watering treatments for 10weeks, at which point plants in all treatments were subjected to a final drought period lasting 8weeks. Plant performance was evaluated by plant biomass and allocation, gas exchange parameters, foliar carbon and nitrogen and stable isotope (δ15N and δ13C) compositions. Plant xylem sap phytohormones were analysed to investigate the effect of microbial inoculation on plant phytohormone profiles and potential relationships with other observed physiological parameters. Across all investigated plant species, inoculation treatments had small effects on plant growth. Further analysis within each species revealed that inoculation treatments did not result in significant biomass gain under well-watered or drought-stressed conditions, and effects on nitrogen nutrition and photosynthesis were variable and minimal. This suggests that the selected commercial microbial inoculant had limited benefits for the tested plant species. Further investigations on the compatibility between the microorganisms (present in the inoculant) and plants, timing of inoculation, viability of the microorganisms and concentration(s) required to achieve effectiveness, under controlled conditions, and field trials are required to test the feasibility and efficacy in actual restoration environments.

The Role of Almond-Leaved Pear Pyrus spinosa Forssk. in Mediterranean Pasturelands Carbon Storage and Woodlands Restoration

A large portion of the Mediterranean basin suffers from a lack of organic carbon in the soil and low woody cover percentages, resulting in a very high risk of desertification. In such conditions, knowing the effects on below and above ground carbon sequestration of pioneer woody species is of great importance, although barely assessed at the individual level. In this study, we first investigated whether almond-leaved pear (Pyrus spinosa) individuals influence soil organic carbon (SOC) concentration and stock in comparison with surrounding pasturelands inside a natural reserve in Sicily, Italy. Second, we evaluated inter individual variability on such storage, testing the effects of plant height, basal diameter, canopy cover and tree structure (single or multiple stems). Soils under pear presented, on average, a significantly higher SOC than pasturelands (3.86% and 3.16%, respectively) as well as a lower bulk density (1.09 and 1.28 g cm−3, respectively). Due to a lower soil compaction, SOC stocks (130.3 and 113.9 Mg ha−1, respectively) did not differ significantly. Below and aboveground biomass carbon accounted for a small fraction of carbon stock, while neither pear structure, age nor tree structure significantly influenced SOC concentration and SOC stock. Despite the need of further investigations, our results indicate that pear may represent an excellent tree species to improve carbon storage, both while triggering the restoration of Mediterranean woodlands or increasing biodiversity in pasturelands and agroforestry systems, that, indeed, can hold high SOC if well managed.

Uncovering historical roots of nature-based solutions: Christian Ludwig Krause's approaches to restoring degraded land in an 18th-century European landscape

Nature-based solutions (NBS) represent a recent umbrella concept to tackle land degradation and other urgent challenges. The concept has deep, often-hidden historical roots. To shed light on these origins, this paper examines 18th-century approaches to combat land degradation in a central European landscape, as documented in a 1773 book by Christian Ludwig Krause. First, historical sources on overexploitation and degradation of forests and grasslands in 18th-century Brandenburg (now part of Germany) are examined to illustrate major challenges of that period. Then, an analysis of Krause's book identifies the problems he addressed and the solutions he proposed in response. Krause astutely diagnosed the interaction of different land uses that led to the loss or degradation of forests and grasslands and then to wind erosion that severely affected agricultural fields. He identified reduced flower availability due to overgrazing as a threat to bees and honey production. His main recommendations include restoration of oak woodlands, establishment of tree plantations, recovery of degraded sandy areas, planting of hedgerows as living fences, and bee gardens. He justified these solutions by highlighting negative socioeconomic consequences of land degradation, such as timber shortages and reduced agricultural yields. He addressed farmers and other stakeholders directly, illustrating expected economic benefits of proposed interventions, including for the well-being of future generations. Krause's ideas stand out for several reasons: (i) they are underpinned by a clear-sighted understanding of natural components and processes, combined with practical experience; (ii) he treated land degradation as a social-environmental phenomenon, highlighting the responsibility of various stakeholders for problems and their solutions, supported by economic reasoning; (iii) he linked different land-use systems and local to regional scales, even incorporating urban-rural coupling of nutrient cycles. Most of his suggestions meet present-day criteria of NBS. Two aspects of his work fall outside the NBS framework: (i) historical data on the efficiency of the proposals are missing and (ii) biodiversity gains are not explicitly included in his proposals - although many of them would result in improved biodiversity. Christian Ludwig Krause can be considered an 18th-century pioneer of NBS, with his systems-based thinking serving as a model even today, and he was also a pioneer of ecological restoration and sustainable land use.

Scenario planning and multispecies occupancy models reveal positive avian responses to restoration of afforested woodlands

Scenario planning is a powerful approach for assessing restoration outcomes under alternative futures. However, developing plausible scenarios remains daunting in complex systems like ecological communities. Here, we used Bayesian multispecies occupancy modeling to develop scenarios to assess woodland restoration outcomes in afforested communities in seven wildlife management areas in Arkansas, U.S.A. Our objectives were (1) to define plausible woodland restoration and afforestation scenarios by quantifying historic ranges of variation in mean tree cover and tree cover heterogeneity from 1986 to 2021 and (2) to predict changes in bird species richness and occupancy patterns for six species of greatest conservation need under two future scenarios: complete afforestation (100% tree cover) and woodland restoration (based on remotely sensed historic tree cover). Using 35 years of remotely sensed tree cover data and 6 years of bird monitoring data, we developed multispecies occupancy models to predict future bird species richness and occupancy under the complete afforestation and woodland restoration scenarios. Between 1986 and 2021, tree cover increased in all study areas—with one increasing 70%. Under the woodland restoration scenario, avian species richness increased up to 20%, and four of six species of greatest conservation need exhibited gains in occupancy probability. The complete afforestation scenario had negligible effects on richness and occupancy. Overall, we found decreasing tree cover to historic levels prior to widespread afforestation would provide community‐level benefits and would do little harm even to forest‐dependent species of conservation concern. Applying multispecies occupancy modeling within a scenario planning framework allows for comparing multiscale trade‐offs between plausible futures.

Study on the impact of vegetation change on ecosystem services in the Loess Plateau, China

Vegetation change has a non-negligible role in the impact of ecosystem services (ESs). Quantitative assessment of vegetation ecosystem services is the basis for sustainable regional development. Using the Chinese Loess Plateau (LP) as the study area, this study firstly analysed the spatial and temporal characteristics of vegetation change and used a Geodetector model to reveal the driving mechanism. Next, this study applied the InVEST model to quantitatively assess the four services of carbon storage, habitat quality, soil conservation and water yield, and explored the vegetation ecosystem service balance through vegetation type transfer. The results showed that (1) there was a trend towards an increase in the area of all vegetation types, with sparse vegetation being the most pronounced. Areas of damaged vegetation were concentrated in urban and peripheral areas, as well as wasteland and bare ground. (2) Annual precipitation, soil types and cumulative afforestation area ratio were the main drivers of vegetation change on the LP. (3) Restoration of woodland enhanced carbon storage, habitat quality and soil retention services for vegetation on the LP, while water yield decreased by 31.66%. The restoration of vegetation area did not enhance all ecosystem services. This study may provide a reference and basis for the sustainable management of regional ecosystems.

Key factors in direct acorn seeding for the successful restoration of open oak woodlands

Little is known about the effectiveness of direct acorn seeding when subjected to different environmental conditions, but without the interference of acorn predation. In order to assess and improve its success, a total of 2400 holm oak acorns from 20 mother trees were sown in three blocks across four sites from southern Spain. Each block was divided into two subplots, in one of which weed competition was mechanically controlled over the study period. Acorns were weighed, protected by a seed shelter, and sown at four different dates between December 2019 and March 2020. Emergence, survival and growth were registered until November 2021. In this last sampling, the aboveground biomass was harvested. Emergence varied from 53.7% of acorns sown in December to 29.4% of those sown in March while survival success after two growing seasons was 27.1% for acorns sown in December as compared to 9.2% of acorns sown in March. Survival success clearly decreased at a higher rate over time in non-treated subplots (12.7%) as opposed to those where the weeds were controlled (22.5%). Emergence, growth, and survival success were highly dependent on the site and the mother tree from which the acorn came. The mass of the emerged acorns was higher than the mass of those that did not emerge. The mean acorn mass of each mother tree was positively correlated with the germination rate and emergence of the seedlings, and with the survival of emerged seedlings and final survival success. In conclusion, we recommend selecting large acorns, sowing early (December), controlling weed competition over time, and selecting mother trees with high germination potential. Seeding success will be lower in drier sites and drier years.

Restoration of Woodland in Inhabited Rural Mountainous Areas and Landscape Transformation in a Vulnerable Environment: The Case of the Village of Vallue, Palmes Region, Haiti

Restoration of Woodland in Inhabited Rural Mountainous Areas and Landscape Transformation in a Vulnerable Environment: The Case of the Village of Vallue, Palmes Region, Haiti

High mountain trees: altitudinal records recently broken for eleven different tree species in Britain

In 2022 a project was initiated utilising citizen science to document observations of trees growing in Britain above 900 m. This focused recording effort contributed to eleven new altitudinal records for tree species in this country, including Sorbus aucuparia at 1150 m and Picea sitchensis at 1125 m (both East Inverness-shire, v.c.96). Some of these observations involved increases of at least 200 m above previous known altitudinal limits. The new records were a mix of small, stunted plants not expected to reach maturity in these extreme environments, as well as arctic-alpine Salix shrubs adapted to low temperatures and exposed conditions. Although these findings are currently too restricted to draw broad conclusions on the impacts of climate warming and land management on tree colonisation in mountain environments, long-term data collection may allow an analysis of drivers of change in the future. Out of a total of 72 tree records above 900 m collated by the author in 2022, 56% were Picea sitchensis, highlighting the ability of this neophyte to spread into high elevation habitats. The project has been useful for generating public interest in biological recording at and above the altitudinal treeline, and the continuation of such work will assist with mountain woodland restoration projects for a variety of ecologically important taxa and plant communities.

Genetic assessment of the value of restoration planting within an endangered eucalypt woodland

Assessment of woodland restoration often focusses on stand demographics, but genetic factors likely influence long-term stand viability. We examined the genetic composition of Yellow Box (Eucalyptus melliodora) trees in endangered Box-Gum Grassy Woodland in SE Australia, some 30 years after planting with seeds of reportedly local provenance. Using DArT sequencing for 1406 SNPs, we compared genetic diversity and population structure of planted E. melliodora trees with remnant bushland trees, paddock trees and natural recruits. Genetic patterns imply that natural stands and paddock trees had historically high gene flow (among group pairwise FST = 0.04–0.10). Genetic diversity was highest among relictual paddock trees (He = 0.17), while diversity of revegetated trees was identical to natural bushland trees (He = 0.14). Bayesian clustering placed the revegetated trees into six genetic groups with four corresponding to genotypes from paddock trees, indicating that revegetated stands are mainly of genetically diverse, local provenance. Natural recruits were largely derived from paddock trees with some contribution from planted trees. A few trees have likely hybridised with other local eucalypt species which are unlikely to compromise stand integrity. We show that paddock trees have high genetic diversity and capture historic genetic variety and provide important foci for natural recruitment of genetically diverse and outcrossed seedlings.