Native Woody Species Research Articles

Native woody species depend on the soil microbiome to establish on burned soils, while non‐native do not

Abstract Wildfires are important natural disturbances with profound ecological impacts. However, our understanding of how to restore plant–soil microbiome interactions following wildfires remains limited, revealing a key knowledge gap in post‐wildfire ecosystem restoration. To assess the restoration of plant‐microbiome interactions in fire‐affected ecosystems, we conducted greenhouse experiments simulating wildfire effects on soil collected from Maulino Coastal Forest of central Chile, a biodiversity hotspot. We measured the plant height and photosynthesis over 90 days, and two‐year survival probability, of three common native (Aristotelia chilensis, Nothofagus glauca and N. alessandrii) and three non‐native species (Eucalyptus globulus, Pinus radiata and Genista monspessulana) planted in three soils (unburned, burned and burned soil inoculated with the native microbiome). Available nutrient concentrations (N, P and K) and activities of microbial enzymes (dehydrogenase, β‐glucosidase and urease) were also measured over 360 days. Available nutrient concentrations were consistently higher in burned and burned‐inoculated soils than in unburned soils. Enzyme activities in unburned and burned‐inoculated soils remained higher than in burned soil, indicating that the native microbiome restored microbial enzyme activities. The increase in height over 90 days was lower in burned soils compared with unburned soils for native species. However, inoculation with the native microbiome mitigated this negative effect, resulting in height increases similar to those in unburned soils. For non‐native species, burning and inoculation had negligible effects on the height increases. Similar patterns were observed for the increase in photosynthetic rate, with native species showing a reduced rate in burned soils, which was offset by microbiome inoculation, while non‐native species were unaffected by both treatments. Survival probability of native species declined in burned soil, but was the same in burned‐inoculated soil as in unburned soil. That of non‐native species was unaffected by burning or by inoculation with the native microbiome. Synthesis and applications. Native microbiomes are evidently promising tools to safeguard ecosystem functionality and mitigate species extinction risks arising from climate change and human‐induced wildfires. We advocate integrating microbiomes into future active restoration strategies for fire‐affected ecosystems.

Agroforestry Contribution to Native Woody Species Conservation, Carbon Sequestration, and Livelihood Benefits in Ethiopia: A Systematic Review

Agroforestry Contribution to Native Woody Species Conservation, Carbon Sequestration, and Livelihood Benefits in Ethiopia: A Systematic Review

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.

Suppression of reed canarygrass by assisted succession: A sixteen‐year restoration experiment

Abstract Assisted succession could enable long‐term restoration where successional trajectories stall due to competition from invasive plants. Many invasives are shade‐intolerant; therefore, interventions reducing light availability should suppress invasion and re‐establish successional processes. However, given how ubiquitous nonlinearities are in ecology, restoration success also depends on identifying critical system thresholds, for example invader abundances below which regeneration of desired species is possible. We report the successful use of assisted succession to restore a swamp forest invaded by Phalaris arundinacea (reed canarygrass; hereafter Phalaris), initiated by a high‐density planting of woody species to outcompete Phalaris by reducing light availability. We established five pre‐planting treatments in a Phalaris near‐monoculture in Wisconsin, USA: herbicide‐only, herbicide+plough, herbicide+burn, mow+herbicide and control. In 2003 we planted 22 tree and shrub species at high densities, then in 2019 we censused the site to: (1) screen for long‐term differences among treatments, (2) evaluate long‐term effects of our interventions on community composition and (3) characterize the critical thresholds that enable invader suppression and restoration success. Vegetation responses and light availability across our four pre‐planting invader removal treatments did not differ. Late fall glyphosate application suppressed Phalaris long enough that a dense canopy of native woody species could establish and eventually out‐shade it. Overstory tree and shrub densities of 0.071/m2 suppressed Phalaris to 50% cover, but, due to nonlinearities, much higher densities were needed to reduce light availability and thus Phalaris cover enough to shift the system from being invader‐dominated. Compositional similarities between juvenile woody species and the overstory suggest a long‐term restoration success. Synthesis and applications. Invasive species management and the restoration of target plant communities can be aided by assisting successional trajectories that have stalled. We document a restoration strategy for forests invaded by shade‐intolerant invaders that is both effective and economical, as only a simple site preparation and single planting effort is required. Establishing a dense canopy of woody species in this way can break the feedbacks maintaining invader dominance and re‐introduce feedbacks enabling long‐term ecosystem recovery. We also illustrate the value of identifying critical thresholds influencing the abundance and impact of key invasive species.

Coordination of water use strategies and leaf economic traits in coexisting exotic and native woody species from evergreen and deciduous broadleaf forests

The leaf economics spectrum (LES) describes the covariation of traits relevant for carbon and nutrient economy in different plant species. However, much less is known about the correlation of LES with leaf water economy, not only because some woody species do not follow the rules, but also because they are rarely tested on the widespread, non-native, fast-growing trees. We hypothesized that fast-growing exotic species that spread on the fast side of the LES coordinate their water-use strategies (WUS) to maintain rapid growth, and that the pattern of coordination differs between evergreen and deciduous forests. Using 4 exotic and 4 native species from evergreen and deciduous broadleaf forests in China, we measured 17 traits of LES and WUS and analyzed their functional roles in different species groups. Our results suggest that LES plays a more important role in the coexistence of species within a community, while WUS contributes more to the distribution of species across different regions. The multidimensional coordination of LES and WUS could better explain the growth and distribution of different plant species and shed light on the coexistence of species from different forest types, especially fast-growing woody exotics.

The use of Groasis Waterboxx devices to improve mineland reclamation efforts by increasing transplant survival and growth of five native woody species

The reclamation of disturbed lands worldwide is a difficult and increasing problem. In the Mountain West region of the United States, mining activities commonly occur in zones dominated by native woody plants. The restoration of woody plants in these areas is challenging, and direct seeding efforts result in poor seedling emergence and establishment. Therefore, seedling transplants are often used, but they frequently experience high mortality during the first year, particularly due to summer stresses. We evaluated if the Groasis Waterboxx device could be used to mitigate drought stress on seedling transplants and improve their establishment on a reclaimed waste rock dump. The Waterboxx device collects precipitation into a polypropylene reservoir and slowly dispenses water onto the soil next to the seedling. To test such a hypothesis, 400 seedlings from five native woody plants (Atriplex canescens, Cercocarpus ledifolius, Pinus edulis, Purshia tridentata, and Rhus glabra) were planted with and without a Waterboxx. The Waterboxx device improved soil water potential, at 40 cm, it took 1 month longer to go below −1 MPa under a Waterboxx. Survival increased 30–65% in four of the five species, and seedling vigor increased for three of the five species. Vigor was higher with all plant species at both planting times and was significantly better in 50% of comparisons. Results support the use of the Waterboxx for improving seedling establishment on mineland overburden sites in the semiarid mountain west. The effectiveness of the Waterboxx device provides merit for future testing where drought challenges seedling establishment.

Assessment and Characterization of the Traditional Parkland Agroforestry Practices in Mid and Lowlands of Bale: In the Case of Goro and Ginnir Districts

Agroforestry parklands are playing an important role, through trees and shrubs providing multiple products and important long-term ecological benefits. Purposive sampling methods were applied to select districts, PAs and farmers which mostly used parkland agroforestry practices. Based on information delivered from informal assessment result, formal survey was done with selected 84 HHHs (sample size) for the study purposes. Based on the existences of long lived parkland agroforestry practice and associated challenges four PAs from Ginir and Goro districts of Bale Zones were selected purposively with assistance of district agriculture office expertise and DAs. Survey results showed the presence of 17 woody species of trees and shrubs representing eleven (11) families at the study areas. Of seventeen (17) woody plant species retained/planted and managed on parklands, 82.4% were native. Fabaceae was the most dominant woody species family which accounted about 41.2% of the total number of species recorded. The Croton macrostachyus Hochst., Faidherbia albida, Cordia africana Lam., Acacia abyssinica Hochst., Junperus procera Hochst and Acacia species were the most frequently observed multipurpose woody species in the study area. Almost all of the respondents did practise different types of management activities or practices for the woody species they owned in parkland of the study areas. This finding revealed that pollarding (33.45%), coppicing (21.08%), branch pruning (35.56) and the rest thinning and protection woody species management practices were applied to the scattered trees on croplands of the study areas. On other side, respondents stated that the major challenges for the improvement of parkland agroforestry practices in the study area were instability of rain fail or drought (34.52%) and shortage of farmlands (21.43%). The finding of this study showed that agricultural landscapes (Parkland agroforestery practices) were the home/host of reasonable number of native woody species flora conservation or it’s almost the remnants of the natural vegetation. Therefore, further need for more comprehensive analysis of the multiple benefits and services provided by parkland trees located on farmlands or the interaction effects of the agroforestery components on soil fertility improvement, crop yields and quality in the future.

Green deserts, but not always: A global synthesis of native woody species regeneration under tropical tree monocultures.

Tree monocultures constitute an increasing fraction of the global tree cover and are the dominant tree-growing strategy of forest landscape restoration commitments. Their advantages to produce timber are well known, but their value for biodiversity is highly controversial and context dependent. Therefore, understanding whether, and in which conditions, they can harbor native species regeneration is crucial. Here, we conducted meta-analyses based on a global survey of the literature and on a database created with local, unpublished studies throughout Brazil to evaluate the regeneration potential of native species under tree monocultures and the way management influences this regeneration. Native woody species regeneration under tree monocultures harbors a substantial fraction of the diversity (on average 40% and 68% in the global and Brazilian surveys, respectively) and abundance (on average 25% and 60% in the global and Brazilian surveys, respectively) of regeneration observed in natural forests. Plantations with longer rotation lengths, composed of native tree species, and located adjacent to forest remnants harbor more species. Pine plantations harbor more native individuals than eucalypt plantations, and the abundance of regenerating trees is higher in sites with higher mean temperatures. Species-area curves revealed that the number of woody species under pine and eucalypt plantations in Brazil is 606 and 598 species, respectively, over an aggregated sampled area of ca. 12 ha. We highlight that the understory of tree monocultures can harbor a considerable diversity of regenerating native species at the landscape and regional scales, but this diversity strongly depends on management. Long-rotation length and favorable location are key factors for woody regeneration success under tropical tree monocultures. Therefore, tree monocultures can play a role in forest landscape restoration and conservation, but only if they are planned and managed for achieving this purpose.

EXPERIMENTALSTUDY ON PARTIAL REPLACEMENT OF COARSE AGGREGATE BY DEMOLISHED CONCRETE WASTE AND ADDED BY PROPHIS JULIFERA ASH

DeteriorationofconcretestructuresmadewithordinaryPortlandcementThe experimental investigations are carried out to study the benefits of Prosopis juliflora in RCC structure by partial replacement of cement. Prosopis juliflora is one among the species that has performed much better than many native woody species. But wide spread Prosopis juliflora has become an invader species, so the removal of the plant is necessary now. At the moment, Prosopis juliflora provides approximately 75% of fuel wood needs of rural people in arid and semiarid regions of India. Prosopis juliflora is xerophytic and is adapted to many soil types under a wide range of moisture conditions. Most of the plant are removed by uprooting and is burnt.

A crop for a forest: Opuntia ficus-indica as a tool for the restoration of Mediterranean forests in areas at desertification risk

IntroductionThe Mediterranean is the European region with the lowest woody cover and the highest level of habitat degradation, being highly susceptible to climate change effects and desertification risk. In such worrying conditions, increasing woody cover and restoring forests is a major goal established in several international commitments. However, recruitment limitation of woody species is rather frequent both within natural regeneration processes and active restoration programs, particularly due to drought, overgrazing, and a lack of post-planting tending operations. Therefore, finding suitable tools to improve the recruitment success of native woody species is of crucial importance.MethodsWe assessed woody natural regeneration under abandoned prickly pear orchards, olive trees, and nearby open areas in three sites under high desertification risk in central Sicily (Italy). Then, we tested for differences in density, richness, diversity, height, and basal diameter of the woody recruiting species between these three habitats.Results and discussionNatural regeneration was widespread under prickly pear, with 94.6% of the sampled plots showing at least one recruit, in comparison to 61.6% of plots under olive and 22.3% in open areas. Natural regeneration density under prickly pears (114 ± 99 individuals m−2) was significantly higher (p < 0.001) than under olive trees (60.4 ± 76.4) and open areas (4.6 ± 9.3). Recruits’ diversity, basal diameter, and height were also significantly higher under prickly pear, concentrating 94.4% of the individuals higher than 100 cm and all late successional species. Our results indicate a great potential for prickly pears to accelerate the natural regeneration of Mediterranean woody species in pear instead of pears under desertification. However, a site-specific evaluation must be made taking into account prickly pear’s historical presence, temporary income as a crop, management capacity and, especially, its invasive potential.

Species traits related to the invasion of woody plants in Patagonian deciduous forests.

The comparison of ecological, phenological, morphological and developmental traits between exotic invasive species and coexisting native species contributes to understand the driving mechanisms of successful invasions. This study aimed to examine which of these traits are related to the invasion of woody plants in the understory of deciduous North Patagonian forests of Argentina. We compared the phenology, shoot growth rate, number of leaves, biomass allocation, leaf herbivory, and recruitment type of two exotic deciduous trees, Crataegus monogyna and Sorbus aucuparia, with those of four coexisting native woody species (one deciduous, one semi-deciduous, and two evergreen species). Spring shoot growth took place several weeks earlier in both exotic species and in the deciduous native species than in the other native species; growth rates were higher in the exotics. Compared to coexisting native species, both exotic species developed shoots that were as long as or longer, had lower biomass allocation to leaves and higher allocation to roots, suffered lower leaf damage by herbivores and exhibited higher seed than vegetative recruitment. This study supports the idea that a combination of phenological, growth rate and mass allocation traits allow exotic species to preempt resources, thus favouring invasion processes.

Investigating physiological effects due to artificial infections of grapevine with <i>Verticillium nonalfalfae</i>

Ailanthus altissima is among the most invasive woody species worldwide, outcompeting native trees. The fungus Verticillium nonalfalfae (VN) is promising for A. altissima biocontrol, and its effects on the host have been studied via visual assessment in a range of host species. However, little research was performed to address fungal effects on the physiological processes of non-target woody plants. We investigated the occurrence of visual and non-visually recognisable perturbations of VN infection on potted vines to evaluate the potential risks of the biocontrol pathogen on viticulture. Eighteen four-years-old Vitis vinifera (cultivar Grüner Veltliner grafted on Kober 5BB) potted plants were inoculated with VN conidial suspension of the fungus (F), while nine plants were treated with sterile water (C, control). Disease symptoms and physiological parameters were monitored throughout the experiment (seven evaluation dates), while leaf water potential, leaf mass per area (LMA) and biomass were measured at the end of the study when plant tissue was sampled for re-isolation of the fungus. In our trial, inoculations with VN induced characteristic wilting symptoms only in Ailanthus (used as side control of the inoculum), while vines remained asymptomatic, thus indicating a high degree of host specificity of VN. Limited or no impact was detected on the physiology of the non-target V. vinifera. Furthermore, the LMA and biomass measured in the two experimental groups were not different. Although fungal colonisation induced vascular discolouration in both species, the fungus could only be re-isolated from dying Ailanthus but not from vine tissue. Results suggest that V. vinifera cv Grüner Veltliner is resistant to the applied VN isolate. However, the susceptibility and physiology of additional grapevine cultivars, as well as other native woody species to VN, should be studied before promoting large-scale use of the biocontrol agent.

Ozone enrichment and drought stress have more negative effects on invasive leguminous woody species than co-occurring native species

Ozone (O3) enrichment and drought stress are common phenomenon of global climate change. However, it remains unknown to what extent these factors might affect leguminous woody plant species invasion. In an open-top chamber (OTC) experiment, we grew four congeneric pairs of invasive and native woody plant species under two levels of O3 concentrations (ambient vs. elevated) and water conditions (dry vs. wet). We studied the effects of O3 enrichment and drought stress on the biomass, biomass allocation and leaf number of these four pairs of invasive vs. native woody species that are common in temperate forests. The results showed that O3 enrichment and drought stress alone reduced the total biomass of invasive woody species significantly greater than those of co-occurring native species. Moreover, O3 enrichment reduced the root biomass allocation of invasive species significantly more than that of native species. Under elevated O3 environments, the ratio of damaged leaves to total leaves for invasive species was 22.6% and 33.9%, and for native species was 13.9% and 24.4%, under dry and wet conditions, respectively. Results suggested that negative effects of O3 enrichment on plants was alleviated under drought conditions, and such negative effects on invasions of woody plant species were both detected from biomass allocation and visible foliar injury perspectives. Our study demonstrated that elevated O3 and drought stress have stronger adverse effects on invasive woody species than that co-occurring native species. The invasive woody plant species may be facilitated for invasion to the areas with lower O3 concentration or higher precipitation.

The influence of seed functional traits and anthropogenic disturbances on persistence and size of the soil seed bank from dry subtropical forest species

Soil seed banks (SSB) are reservoirs of viable mature seeds that play a crucial role in the dynamics and recovery of vegetation following disturbances. Despite its importance, there is still limited understanding of their characteristics of SSB in semiarid subtropical ecosystems. Our objective was to evaluate the effects of wildfire and roller-chopping on the size and persistence of the SSB of six native woody species, considering the influence of seed functional traits (FT). This study was conducted in dry subtropical forests of the western Argentine Chaco region. We evaluated SSB of six woody species: Aspidosperma quebracho-blanco (Aqb); Schinopsis lorentzii (Sl); Sarcomphalus mistol (Sm); Senegalia gilliesii (Sg) and Vachellia aroma (Va) in experimental plots located in two sites (forest plots of ca. 5 ha): forests without disturbance within the last four decades (conserved forest - CF) and forests subjected to fires and mechanical treatments for the partial removal of the shrub layer (roller-chopping and burned forest -RBF). Samples of the SSB were taken under the canopy of six focal individuals of each species in two reproductive seasons between 2016 and 2018. Seeds from ten mature trees of each species were collected to characterize their functional traits (shape and seed mass) related to their aptitude to form the SSB. Three groups of species were identified based on FT analysis: I-large, compressed seeds (Sl, Aqb and Sg); II- medium-size subspherical seeds (Va and Nn); and III- large spherical seeds (Sm). Aqb, Sl, Nn, and Va presented significant differences in the size of their SSB when comparing between sites and sampling years (p = 0.0013; p = 0.0006; p = 0.0020; p = 0.0151, respectively), but no clear patterns emerged among them. The SSB from Aqb and Va were greater in RBF than in CF, only during the second sampling season (105.3 ± 35.2; 352.6 ± 133.4 seeds.m−2, respectively). Sl also exhibited the highest SSB (97.7 ± 30.5) in the second year of sampling, while Nn showed the largest SSB in the first year, (1569.0 ± 847.0 seeds.m−2), both within CF. Finally, Sm and Sg did not present significant differences in their SBB between sites and years. We concluded that all studied species form transient SSB and that the shape index type II favors seed burial, so increasing SSB size and viability. Forest disturbances differentially affect the SSB of woody species in the dry subtropical Chaco because some species decreased, increased or showed no effects during different reproductive seasons. Thus, the potential long-term influence on the dynamics and resilience of dry forests in the subtropics needs to be monitored in the long term.

Species diversity and vegetation structure of woody plants in regenerating Juniperus forest replacing Eucalyptus in the conservation area of Gullele Botanic Garden, Addis Ababa, Ethiopia

The Gullele Botanic Garden (GBG) adjoins the north-western limit of the city of Addis Ababa, capital of Ethiopia. The floristic composition, species diversity and vegetative structure of the woody plant species in the conservation area of the garden are presented from 81 plots (20 m x 20 m). A total of 104 woody plant species (90% indigenous, the rest planted or naturalised) of 83 genera and 47 families were recorded. The dominant families were Fabaceae and Asteraceae. The number of individuals of the most dominant species, Juniperus procera, decreases with increasing DBH and height class, which indicates a good and healthy reproduction potential of the species in the conservation area. No statistically meaningful plant communities could be identified in the conservation area. Many of the species present in the dry forests of the central Ethiopian plateau occur in GBG. The species richness appears to be relatively high in comparison with what other researchers have found in natural forests on the highland plateau; 87 native woody species (of which 11 are planted) in GBG, 57-97 (cumulatively 127) in Wof-Washa, 32-85 (cumulatively 113) in Menagesha and 41-77 (cumulatively 81) in Chilimo, 34-67 (cumulatively 69) in Entoto, though the definitions for woody species have varied between studies. Clustering on the floristic data gives four partly overlapping clusters with the lowest p-values for indicator species, but the distribution of the plots on clusters changes notably if information on Eucalyptus is in- or excluded. Ordination graphs with partly overlapping groups of species are presented. The findings in this paper can serve as a baseline to follow the regeneration of the conservation area towards natural forest. This is needed for future management and sustainable utilization of the forest species at local and national levels.

Development of the breeding bird community of a silvoarable agroforestry system with short rotation coppice strips over a 16-year period

AbstractModern silvoarable agroforestry systems (AFS) with short rotation coppice strips (CS) are considered as a potential measure to increase structural diversity in agricultural landscapes and to promote biodiversity while simultaneously producing arable crops and woody biomass. However, studies investigating the actual potential of these novel land use systems to promote biodiversity are scarce. We therefore investigated the importance of a silvoarable AFS with different CS variants as habitat for breeding birds on an experimental site in northern Germany, which was studied several times over a 16-year period since its establishment. In addition, the habitat function and quality of CS was compared with hedgerows. The results show that establishing CS on arable land creates additional habitats for shrub and tree breeding species and thus increases species numbers and territory densities. Tree harvest resulted in a decrease in species numbers and densities. However, since Aspen rows (for timber production) or native woody species were retained during harvesting in some CS, suitable nesting opportunities for some species remained. A sharp decline in Skylark territories was observed within the open land of the AFS, from nine breeding pairs in the year after establishment (2009) to only two breeding pairs each in 2022 and 2023. Compared to CS, hedgerows were more species-rich and had much higher territory densities. We conclude that the integration of CS into croplands can promote some species of woody habitats, especially if measures such as the integration of trees of different heights or native woody species and sectional harvesting are implemented. However, CS still clearly lag behind hedgerows in terms of their habitat quality. Furthermore, the establishment of CS may have negative effects on threatened open land species like the Skylark. The requirements of these species should therefore be considered when planning AFS. Establishing AFS with CS could especially be an option in cleared, intensively used agricultural landscapes, where CS could represent a trade-off between the promotion of birds and agricultural production.

Topsoil and Vegetation Dynamics 14 Years after Eucalyptus grandis Removal in Eastern Cape Province of South Africa.

A great deal of effort has been made to clear invasive alien plants in South Africa, yet it remains unclear if the clearing efforts are yielding positive soil and vegetation recovery trajectories. A few short-term studies have been conducted to monitor soil and vegetation recovery after alien plant removal in South Africa, but convincing, long-term monitoring studies are scarce yet needed. We investigated topsoil and vegetation recovery following Eucalyptus grandis removal 14 years ago by Working for Water in Makhanda, Eastern Cape province of South Africa. The detailed topsoil and vegetation surveys were conducted on forty 10 m × 10 m plots that were in paired cleared and natural sites. The results show no significant differences for the measured soil pH, total N, total C, K, Ca, and Na between the cleared and natural sites, an indication that the two sites are becoming similar. Similarly, the gravimetric soil moisture content shows no significant differences between the two sites, although monthly variations are observed. The topsoils in the cleared sites are hydrophobic as compared to those in the natural sites, which are wettable. We observed no significant vegetation diversity differences between the two sites, with native woody species, such as Crassula pellucida and Helichrysum petiolare, frequently occurring in the cleared sites. We recorded low reinvasion by E. grandis and other secondary invaders like Acacia mearnsii and Rubus cuneifolius in the cleared sites. Based on these results, we conclude that 14 years after E. grandis clearing, both topsoil and vegetation recovery are following a positive trajectory towards the natural sites. However, both reinvasion and secondary invasion have the potential to slow down soil and native vegetation recovery. Recommendations such as timeous follow-up clearing and incorporating restoration monitoring in the WfW clearing programme are discussed.

Survival of Seedlings of Native Woody Species in the Rehabilitation of Gold Mined-Site within a Three Years Old Acacia mangium Willd Plantation of St. Elizabeth-Mahdia, Guyana

Survival of Seedlings of Native Woody Species in the Rehabilitation of Gold Mined-Site within a Three Years Old Acacia mangium Willd Plantation of St. Elizabeth-Mahdia, Guyana

Indicators of ecosystem degradation along an elevational gradient in the Mediterranean Andes

Successful restoration measures need a good understanding of how the composition, structure, and functioning of ecosystems change with degradation and what the best indicators of these changes are. To answer these questions, we worked on four ecosystem types in the Mediterranean Andes mountains in central Chile (from sclerophyllous forest to Andean shrublands), which represent an elevational gradient from 700 to 3,250 m. We sampled three plots on each of the three degradation levels (low, medium, and high) for each ecosystem at increasing distances from goat corrals. We measured 35 indicators that describe vegetation (14), soil (15), and ecosystem processes (6) for one growing season. Degradation caused a decrease in shrub cover, shrub productivity, the Normalized Community Structure Integrity Index (CSIIn), litter depth, total soil nitrogen and C/N ratio, and an increase in clay content. Plant species indicating low degradation were consistently native woody species. When comparing ecosystems (i.e., at different elevations) against the type of variable, process-based indicators showed more statistically significant differences. Based on their consistency across ecosystems and ease of measurement, we recommend using shrub cover and litter depth as indicators of degradation. Finally, we concluded that ecosystems are highly degraded when vegetation- and process-based indicators change ∼ 60% or when soil indicators change ∼ 25%. These results could also be used to set goals for restoration projects in these mountain ecosystems.

Woody Plant Encroachment in a Seasonal Tropical Savanna: Lessons about Classifiers and Accuracy from UAV Images

Woody plant encroachment in grassy ecosystems is a widely reported phenomenon associated with negative impacts on ecosystem functions. Most studies of this phenomenon have been carried out in arid and semi-arid grasslands. Therefore, studies in tropical regions, particularly savannas, which are composed of grassland and woodland mosaics, are needed. Our objective was to evaluate the accuracy of woody encroachment classification in the Brazilian Cerrado, a tropical savanna. We acquired dry and wet season unmanned aerial vehicle (UAV) images using RGB and multispectral cameras that were processed by the support vector machine (SVM), decision tree (DT), and random forest (RF) classifiers. We also compared two validation methods: the orthomosaic and in situ methods. We targeted two native woody species: Baccharis retusa and Trembleya parviflora. Identification of these two species was statistically (p < 0.05) most accurate in the wet season RGB images classified by the RF algorithm, with an overall accuracy (OA) of 92.7%. Relating to validation assessments, the in situ method was more susceptible to underfitting scenarios, especially using an RF classifier. The OA was higher in grassland than in woodland formations. Our results show that woody encroachment classification in a tropical savanna is possible using UAV images and field surveys and is suggested to be conducted during the wet season. It is challenging to classify UAV images in highly diverse ecosystems such as the Cerrado; therefore, whenever possible, researchers should use multiple accuracy assessment methods. In the case of using in situ accuracy assessment, we suggest a minimum of 40 training samples per class and to use multiple classifiers (e.g., RF and DT). Our findings contribute to the generation of tools that optimize time and cost for the monitoring and management of woody encroachment in tropical savannas.