Hacia la restauración con Annona glabra (Annonaceae) de una selva inundable: establecimiento y crecimiento de plántulas, y cambio en la vegetación acompañante

The expansion of cattle ranching in the coastal plain of the Gulf of Mexico is transforming freshwater swamps resulting in the reduction of swamps area and the introduction of invasive exotic grasses. This study seeks to determine the structure of the remaining population of Annona glabra in a grassland, evaluate vegetation and environmental conditions of the grassland, and determine the germination capability of A. glabra under different cover conditions of grass growth and two flood levels. The study area is a flooded grassland invaded by Echinochloa pyramidalis in central Veracruz, Gulf of Mexico. In the grassland, we censused and mapped the remaining individuals of A. glabra. We sampled the vegetation and measured the physicochemical characteristics of the soil and water. To evaluate the effect of the invasive grass on the germination of A. glabra seeds, we designed two greenhouse experiments: one (E1) under soil moisture at field capacity and another (E2) under flooded conditions. We found 312 remnant individuals. We recorded 31 plant species, most (72.7%) classified as aquatic/semiaquatic. The relative importance value was highest for E. pyramidalis, Mimosa pigra, and Eleocharis mutata. BEST analysis did not detect significant correlations between vegetation and physicochemical variables, indicating homogeneous environmental conditions. Seed germination was above 80% in E1 and below 20% in E2 in all grass cover levels. Although flooding decreases germination rates, substantial proportion of seeds can germinate, suggesting that natural succession is viable. Based on our results, the flooded grassland has conditions to restore swamp.

BackgroundThe occurrence of climate change at an unprecedented scale has resulted in alterations of ecosystems around the world. Numerous studies have reported on the potential to slow down climate change through the sequestration of carbon in soil and trees. Freshwater wetlands hold significant potential for climate change mitigation owing to their large capacity to sequester atmospheric carbon dioxide (CO2). Wetlands among all terrestrial ecosystems have the highest carbon density and are found to store up to three to five times more carbon than terrestrial forests. The current study was undertaken to quantify carbon stocks of two carbon pools: aboveground biomass (AGB) and belowground biomass (BGB). Chosen study sites; Kolonnawa wetland and Thalawathugoda wetland park are distributed within the Colombo wetland complex. Colombo was recognized as one of the 18 global Ramsar wetland cities in 2018. A combination of field measurements and allometric tree biomass regression models was used in the study. Stratification of the project area was performed using the normalized difference vegetation index (NDVI).ResultsThe AGB carbon stock, across strata, is estimated to be in the range of 13.79 ± 3.65–66.49 ± 6.70 tC/ha and 8.13 ± 2.42–52.63 ± 10.00 tC/ha at Kolonnawa wetland and Thalawathugoda wetland park, respectively. The BGB carbon stock is estimated to be in the range of 2.47 ± 0.61–10.12 ± 0.89 tC/ha and 1.56 ± 0.41–8.17 ± 1.39 tC/ha at Kolonnawa wetland and Thalawathugoda wetland park, respectively. The total AGB carbon stock of Kolonnawa wetland was estimated at 19,803 ± 1566 tCO2eq and that of Thalawathugoda wetland park was estimated at 4180 ± 729 tCO2eq.ConclusionsIn conclusion, the study reveals that tropical freshwater wetlands contain considerable potential as carbon reservoirs. The study suggests the use of tropical freshwater wetlands in carbon sequestration enhancement plans in the tropics. The study also shows that Annona glabra, an invasive alien species (IAS), has the potential to enhance the net sink of AGB carbon in these non-mangrove wetlands. However, further studies are essential to confirm if enhanced carbon sequestration by Annona glabra is among the unexplored and unreported benefits of the species.

Tropical grassy biomes have been widely neglected for conservation and, after unplanned land use conversion, ecological restoration becomes urgent. The majority of interventions have been based on the misapplication of forest restoration techniques, because there are no validated techniques to restore the species‐rich ground layer. In search for innovative techniques to restore the herbaceous layer of the cerrado vegetation, we carried out an experiment based upon topsoil and hay transfer, in the state of São Paulo, Brazil. The restoration treatments were: (1) transfer of topsoil collected at the end of the dry season; (2) topsoil collected at the end of the rainy season; (3) transfer of hay collected at the end of the dry season; (4) topsoil + hay collected at the end of the dry season; and (5) control. We used an old‐growth grassland as source of material and as reference ecosystem to assess the efficacy of the restoration techniques applied to an area severely degraded after invasion by African grasses. After 211 days, hay transfer apparently inhibited germination and did not contribute to grassland vegetation recovery. Topsoil transfer, however, was effective at reintroducing herbaceous plants, including target species. The season of topsoil collection mattered: material collected at the end of the rainy season provided better results in terms of density and richness of the restored community than that from the dry season. The remaining challenge is to find sources of topsoil not invaded by exotic grasses in large enough amounts to support restoration initiatives without jeopardizing the source ecosystems.

Exotic grasses are becoming increasingly abundant in Neotropical savannas, with Melinis minutiflora Beauv. being particularly invasive. To better understand the consequences for the native flora, we performed a field study to test the effect of this species on the establishment, survival and growth of seedlings of seven tree species native to the savannas and forests of the Cerrado region of Brazil. Seeds of the tree species were sown in 40 study plots, of which 20 were sites dominated by M. minutiflora, and 20 were dominated by native grasses. The exotic grass had no discernable effect on initial seedling emergence, as defined by the number of seedlings present at the end of the first growing season. Subsequent seedling survival in plots dominated by M. minutiflora was less than half that of plots dominated by native species. Consequently, at the end of the third growing season, invaded plots had only 44% as many seedlings as plots with native grasses. Above‐ground grass biomass of invaded plots was more than twice that of uninvaded plots, while seedling survival was negatively correlated with grass biomass, suggesting that competition for light may explain the low seedling survival where M. minutiflora is dominant. Soils of invaded plots had higher mean Ca, Mg and Zn, but these variables did not account for the higher grass biomass or the lower seedling survival in invaded plots. The results indicate that this exotic grass is having substantial effects on the dynamics of the tree community, with likely consequences for ecosystem structure and function.

Background and aims Wetlands are important carbon sinks across the planet. However, soil carbon sequestration in tropical freshwater wetlands has been studied less than its counterpart in temperate wetlands. We compared carbon stocks and carbon sequestration in freshwater wetlands with various geomorphic features (estuarine, perilacustrine and depressional) and various plant communities (marshes and swamps) on the tropical coastal plain of the Gulf of Mexico in the state of Veracruz, Mexico. These swamps are dominated by Ficus insipida, Pachira aquatic and Annona glabra and the marshes by Typha domingensis, Thalia geniculata, Cyperus giganteus, and Pontederia sagittata.

Current advancements in the study of the theoretical basis of species interactions are helping scientists understand the basic parameters governing the dynamics of the interactions between generalist herbivores and their target plants. In practice, however, both inter- and intra-specific interactions between plants (as well as between herbivores and plants) within multispecies systems that are under the influence of interrelated biotic and abiotic variables are difficult to predict. Here, we discuss our findings on the effect of simulated herbivory on Mimosa pigra L. leaves on seedling survivability. In Malaysia, M. pigra, a semi-aquatic invasive plant introduced from the South American region, is already creating an ecological problem, especially in wetland habitats. To better understand the impact of herbivores on the M. pigra population, a simulated experiment of the herbivory effect on Mimosa seedlings was conducted. This experiment combined two treatments of simulated herbivory on the leaves of established Mimosa seedlings, that is, a two-level intensity treatment (50 and 100 % defoliation) and a seven-level frequency treatment (one to seven defoliations). The data suggest that Mimosa is highly resilient against herbivory. This plant was able to compensate for repeated losses, thus suggesting that the introduction of herbivores in an effort to totally eradicate the Mimosa population is unlikely to be successful.

Purpose: High-voltage electrical equipment requires grounding installation to protect lives in freshwater swamps with a hydrogen potential of 6.75. To build a grounding structure, it is necessary to know the resistance value and grounding materials, namely, copper-coated rod electrodes at different depths. Research methodology: The research was conducted in a freshwater swamp close to the shampooing substation using field observations and direct measurements of soil resistance values, followed by a literature review and comparisons using COMSOL simulation and FEM Analysis. Results: The results of direct research and simulations indicate that to accomplish a grounding resistance value < 5 ? according to the PUIL 2011 standard for a single-rod system made of copper, it is necessary to optimize the depth of the grounding electrode within a range of 10 m, which differs from the simulation results of ground resistance measurement and the Comsol application. The percentage error was 1.05%. Conclusion: The findings demonstrate that increasing electrode depth effectively reduces grounding resistance in freshwater swamp environments, though variations exist between field and simulated data. Limitations: This study analyzed the results of measurements and grounding analysis using COMSOL Multiphysics at a depth of 1 m for a particular type of copper-coated round rod electrode at depths of 1, 1.5, and 2 m. Contributions: The results of this study offer information on the usefulness of grounding resistance in freshwater wetlands with a pH greater than 6, where several rod electrode types can be utilized for comparison in future research.

1Population increases inSolidago altissima, an aggressive invader in central Europe, can be due to clonal growth by rhizomes or sexual reproduction by seeds. We studied transitions between different reproductive stages, to assess the potential ofS. altissimato colonize new habitats by seed, and the influence of annual mowing on the dynamics of seeds and juvenile plants.2The dispersal of the numerous achenes, their subsequent fate on and in the soil, and the growth and survival of seedlings and juvenile plants were followed from 1988 to 1990 in an old‐field population.3The seed rain was 49 000 seeds m−2per annum in unmown and 1800 seeds m−2per annum in adjacent mown plots. Survivorship and germinability of seeds in the soil decreased rapidly in the first 3 months after dispersal. Thereafter the declines were much slower. Germination within the established vegetation was very rare: only 12 out of 150 000 experimentally sown seeds (0.008%) became seedlings.4The survival and growth of seedlings transplanted into closed vegetation increased with age and developmental stage. Nevertheless, no transplants flowered during the 24 months over which their fate was followed.5Mowing affected neither seed survival nor germinability, nor did it have any effect on the growth, survival and reproduction of seedlings or juvenile plants.6The creation of 1‐m2openings in the vegetation strongly increased the number of emerging seedlings. Production of achenes was high (c. 20 000 per sexual shoot) and seed rain data suggested that 80–90% of all seeds may have been dispersed outside the study area. The colonization of nearby open sites is therefore quite probable.7Thus, mowing in late summer to control the growth ofS. altissimadoes not provide opportunities for further seedling establishment in existing populations and may prevent the colonization of new sites by reducing seed supply from the source population.

Plantation agriculture perturbs native flora of ecosystems. This impacts vegetation biodiversity, through species invasion and shift in weeds population dynamics. Oil palm plantations are common in tropical landscapes, and can cause long-term floristic changes. There is paucity of knowledge on inventory and potential impacts of the plantation on community structure of plants. This study investigated herbaceous flora diversity and phytosociology as indicators of appropriateness of management strategy in the University of Ibadan oil palm plantation. The study site is located in a lowland rainforest at the Teaching and Research Farm, University of Ibadan, Ibadan, Nigeria on 07°27`253`N latitude and longitude 03°53`427`E. A systematic sampling was employed to enumerate herbaceous flora of a hectare mega plot. The hectare was laid along 100 m transects at 10 m intervals, with 10 m separating each transect. Each transect was laid to cut across middle of 9 m x 9 m x 9 m plant spacing for oil palm. Data were collected on species composition, frequency and density for determination of relative importance value (RIV), species diversity, ordination and classification. The plantation consisted of 32 herbaceous species in 15 plant families. Commelina erecta had the highest RIV (12.621) while Alchornea cordifolia had the least (RIV=0.288). Diversity indices indicated high species richness (Simpson Index = 0.909) among enumerated species and species co-dominance (D = 0.091) Ordination biplots indicated three distinct vegetation structures (Secondary, wetland, dryland/fallow). Classification model showed Commelina erecta had widest coverage of 92% in distribution at the site followed by Commelina benghalensis at 88%. The Oil palm plantation is heterogeneous in species composition, and was not detrimentally invaded. Weeding regimes and other agronomic practices in the plantation should be ecologically integrated to conserve its native vegetation.

The long-term ecological success of compensatory freshwater wetland projects has come into question based on follow-up monitoring studies over the past few decades. Given that wetland restoration may require many years to decades to converge to desired outcomes, long-term monitoring of successional patterns may increase our ability to fully evaluate success of wetland mitigation projects or guide adaptive management when needed. In Portsmouth, New Hampshire a 4 ha wetland was constructed in an abandoned gravel quarry as off-site compensatory mitigation for impacts to a scrub-shrub swamp associated with property expansion. Building upon prior evaluations from 1992 and 2002, we conducted a floral survey in 2020 to compare results with prior surveys to document vegetation successional trends over time. In addition, we monitored the avian community throughout the growing season as a measure of habitat quality. The plant community mirrored documented successional trends of freshwater wetland restoration projects as native hydrophytes dominated species composition. Plant species composition stabilized as the rate of turnover, the measurement of succession, declined by nearly half after 17 years. Researchers should consider long-term monitoring of specific sites to better understand successional patterns of created wetlands as we documented long time frames required for the development of scrub-shrub swamps, red maple swamps, and sedge meadows. High species richness was attributed to beaver activity, topographic heterogeneity from Carex stricta tussocks, and the seed bank from the application of peat from the original wetland. Habitat heterogeneity of open water, herbaceous cover, and woody vegetation supports a diverse avian community including 11 wetland dependent species. Although the mitigation project has not created the full area of lost scrub-shrub swamp after 35 years, it has developed a structurally complex habitat and diverse avian community that effectively provides the functions and values of the impacted system.

The long-term ecological success of compensatory freshwater wetland projects has come into question based on follow-up monitoring studies over the past few decades. Given that wetland restoration may require many years to decades to converge to desired outcomes, long-term monitoring of successional patterns may increase our ability to fully evaluate success of wetland mitigation projects or guide adaptive management when needed. In Portsmouth, New Hampshire a 4 ha wetland was constructed in an abandoned gravel quarry as off-site compensatory mitigation for impacts to a scrub-shrub swamp associated with property expansion. Building upon prior evaluations from 1992 and 2002, we conducted a floral survey in 2020 to compare results with prior surveys to document vegetation successional trends over time. In addition, we monitored the avian community throughout the growing season as a measure of habitat quality. The plant community mirrored documented successional trends of freshwater wetland restoration projects as native hydrophytes dominated species composition. Plant species composition stabilized as the rate of turnover, the measurement of succession, declined by nearly half after 17 years. Researchers should consider long-term monitoring of specific sites to better understand successional patterns of created wetlands as we documented long time frames required for the development of scrub-shrub swamps, red maple swamps, and sedge meadows. High species richness was attributed to beaver activity, topographic heterogeneity from Carex stricta tussocks, and the seed bank from the application of peat from the original wetland. Habitat heterogeneity of open water, herbaceous cover, and woody vegetation supports a diverse avian community including 11 wetland dependent species. Although the mitigation project has not created the full area of lost scrub-shrub swamp after 35 years, it has developed a structurally complex habitat and diverse avian community that effectively provides the functions and values of the impacted system.

Background: Wetlands in Neotropics harbor high fungal diversity, including arbuscular mycorrhizal fungi (AMF) and dark septate endophytes (DSE). This study describes the interaction of plant roots with AMF and DSE in a freshwater wetland belonging to a hotspot of biodiversity.
 Hypothesis: Differential root colonization between arbuscular mycorrhizal and dark septate endophyte fungi is influenced by plant species and abiotic conditions in a freshwater wetland. 
 Studied species: Plant species colonized by arbuscular mycorrhizal and dark septate endophyte fungi.
 Methods: Properties of soils and the water column, floristic composition, root colonization by AMF and DSE, and molecular identification of AMF inside roots were studied.
 Results: Soils were Gleysol and flooded during the rainy season. Most of identified plant species were herbaceous, with Cyperus articulatus and Mimosa pigra as the dominant species. Seven of 8 analyzed plant species exhibited differential co-colonization between AMF and DSE. Repeated sampling for one year under flooding/dry conditions demonstrated that C. articulatus and M. pigra were mainly associated with DSE and AMF, respectively. A positive correlation between dissolved O2 in the water column and fungal colonization was observed in C. articulatus . Glomerales and Archaeosporales were molecularly identified inside roots containing arbuscules of M. pigra .
 Conclusions: Findings highlight differential coexistence between AMF and DSE in plant roots; fungal colonization was influenced by flooding/dry conditions in a neotropical wetland; the community of AMF inside arbusculated roots of M. pigra includes at least four clades.

Despite their classification as tidal freshwater swamps, research conducted at the Nanticoke River in Maryland and Delaware suggests that ecologically significant salinity gradients develop during droughts. While average salinity in these swamps may meet the criterion for “fresh water” of <0.5 parts per thousand (ppt) (Cowardin et al. 1979), significant variation in swamp vegetation and seed banks are observed as distance upstream increases. During a drought year, a salinity gradient ranging from 0 to 7 ppt developed across the upper estuary, suggesting that vegetation patterns were related to periodic saltwater intrusion events. The Nanticoke River is located on the Delmarva Peninsula in Maryland and Delaware and is a major tributary of the Chesapeake Bay (Figure 6.1). The Nanticoke watershed encompasses about 86,200 ha in Maryland and 127,500 ha in Delaware. The Nature Conservancy (TNC) designated the watershed as both a Bioreserve and a Last Great Place in 1991 (TNC 1998). Almost 200 rare, threatened, or endangered species of plants (20 globally rare) and 70 rare, threatened, or endangered species of animals (5 globally rare) occur within several significant community types, including freshwater intertidal wetlands. The freshwater intertidal wetlands of the Nanticoke River watershed include about 2,000 ha of freshwater tidal marsh, 2,800 ha of freshwater tidal swamp forest, and 360 ha of freshwater tidal shrub swamp (McCormick

QuestionAssessing the natural regeneration potential of degraded savannas is a crucial step in restoration planning, since that assessment will define the need for and costs of active intervention. Predicting natural regeneration, however, depends on the mechanistic understanding of ecosystem resilience. Here, we searched for the factors modulating plant communities spontaneously regenerating in abandoned pastures.LocationTropical savanna (cerrado), Brazil.MethodsOver two years, we quantified changes in the structure, richness and species composition of plant communities in 29 secondary savannas resulting from pasture abandonment. We then investigated the influence of soil and landscape attributes, exotic grass cover and time since pasture abandonment on the recovery rate and species composition of these communities.ResultsThe wide variation among sites was not explained by time since abandonment or distance to the nearest remnant native vegetation. Soil attributes, exotic grasses and native vegetation cover around a pasture explained a small fraction of the variation in the recovery rate. We did not find an isolated factor or a robust set of factors explaining the variation in the recovery rate for all vegetation attributes. Species composition was slightly influenced by exotic grasses, soil penetration resistance, proportion of fine soil particles and time since abandonment. Colonization and resprouting by savanna specialists over the two‐year period were hindered by exotic grasses.ConclusionThe use of predictive models based on soil properties, exotic grasses, landscape attributes or time since abandonment is unfeasible for inferring the recovery rate of savanna structure and richness after pasture abandonment. Case‐by‐case monitoring is required to support decisions on restoration intervention. Other factors, which are almost impossible to obtain, such as land‐use practices and history and the taxonomic or functional composition of pre‐existing vegetation, can potentially influence the recovery rate. Exotic grasses must be controlled to favour colonization and resprouting by savanna specialists.

This paper demonstrates the potential for restoring a range of habitats by comparing the efficacy of different techniques for restoring lowland dry Atlantic heathland in Dorset, UK, under current and future climatic conditions. The success of different treatments in reducing soil pH and concentrations of the most important macronutrient, phosphorus, on improved pasture adjacent to Hartland Moor National Reserve in Dorset are discussed. The treatments applied were soil removal, soil acidification using elemental sulfur, soil acidification using ferrous sulfate, and nutrient removal. The treatment that most successfully reduced extractable phosphate was soil removal. Nutrient removal produced no significant decrease in extractable phosphate over 7 years study. Soil acidification with sulfur most successfully reduced pH. Under the present climatic conditions, the elemental sulfur treatment produced far more abundant heather growth than soil removal. This study suggest that restoration techniques are likely to change in their relative effectiveness as climate changes and that this may have different consequences for low and high trophic level species.