Forest Recovery Research Articles

Assessment of Taungya agroforestry system in dryland forests rehabilitation in Sudan

The decline of the forest cover due to deforestation and agricultural expansion in Sudan has reached a critical situation. Taungya agroforestry systems have been used as a strategy to safeguard against this process, allowing farmers to cultivate their subsistence crops at the early stage of tree plantations. The current study research tackled Nabag Forest Reserve (NFR) as a case study to assess and explore <em>Taungya</em> agroforestry system as a practice used for forest rehabilitation in the study area. Satellite images of Landsat 5 Thematic Mapper, and Landsat 8 Operational Land Imager/Thermal Infrared Sensor of 1991, 2001, 2011, and 2021 were used to generate forest cover maps. Both unsupervised and supervised classification, as well as ground truth points, were applied to classify the vegetation cover in NFR as dense forest (DF), light forest (LF), agricultural field (AF), and bare land (BL). The results showed that two trends of forest cover changes occurred in NFR between 1991-2001 and 2011-2021. It was well explored that through <em>Taungya </em>agroforestry, there was a considerable increase in forest cover over this period. This could be clearly detected by increasing dense forest and light forest cover by 1041.73 ha (24.95%) and 2.95 ha (0.07%), respectively and decreasing of bare land and agricultural field by 409.79 ha (9.81%) and 634.52 ha (15.15%) during the addressed period. The findings of the study indicated that <em>Taungya</em> agroforestry system could be a feasible land-use alternative for forest recovery in the dry land of Sudan.

Pre-fire measures of boreal forest structure and composition inform interpretation of post-fire spectral recovery rates

Wildfire is a key driver of forest dynamics in boreal forests; however, the annual area burned in boreal forests is highly variable, with increasing wildfire activity documented over the past half century. Post-fire recovery has important implications for carbon balance, and for the wide range of ecosystem goods and services provisioned by the boreal forest. Monitoring post-fire recovery is challenging given the vast and often inaccessible areas impacted, coupled with the marked variability in post-fire conditions and recovery processes. Field assessments of recovery are constrained in space and time, whereas remotely sensed data are spatially explicit, cover large areas, and can retrospectively provide assessments of pre- and post-fire conditions and establish spectral recovery baselines. However, there is a need to link spectral measures of recovery to manifestations of post-fire forest recovery on the ground. Understanding how different forest characteristics influence spectral recovery is key to the successful application of spectral recovery metrics for forest management applications in different forest environments. Herein, using a synthesis of plot data for the North American boreal forest, we assess the influence of pre- and post-fire field-measured characteristics on spectral recovery rates, with a focus on stem density and composition in Canadian boreal forests. Plots that experienced rapid spectral recovery (as measured using Landsat-derived NBR time series data) were associated with a transition from conifer to broadleaf or were broadleaf pre-fire. Plots that experienced a decrease in stem density took significantly longer to spectrally recover than plots that experienced no change in stem density. Plots that had not yet spectrally recovered by the end of the time series were associated with higher elevations, drier sites, greater pre-fire basal area, and had the greatest change magnitude. Our results emphasize that recovery is a process that is highly variable and that knowledge of pre-fire condition is important for characterizing and interpreting measures of post-fire spectral recovery for forest management applications. Remotely sensed time series data are uniquely able to provide information on both pre- and post-fire condition. Our analysis of pre- and post-fire field measures provided novel insights regarding the influence of forest composition and changes in stem density on measures of post-fire spectral recovery in boreal forests.

Resilience and successional trends of woody vegetation in seasonally dry tropical forests

Abstract Understanding the recovery time of vegetation structure and species composition to estimate the resilience of seasonally deciduous tropical forest (SDTF) is fundamental for conservation actions. Related information is still scarce for the semi-arid Brazilian SDTF (locally called Caatinga), which covers more than 800 000 km2 in the northeast of Brazil. We aimed to estimate how long it takes for 11 attributes of vegetation structure and species composition, separately and aggregated, to become similar to an old-growth forest (OGF). The attributes were floristic composition, species richness, Shannon diversity index, plant density, median and maximal diameters and height, basal area, volume and aboveground biomass. The attributes’ regeneration ratios were aggregated as an arithmetic average and a geometric average, based on a variance–covariance analysis. The ratios were determined in chronosequences (5, 15, 25 and 35 regeneration years and an OGF) of SDTF, in three different locations in Ceará state. Plant density, which had a unimodal tendency, reached a peak at 15 years and then decreased, although it was still greater than that of the OGF after 35 years. Richness and diversity, with monotonic trends, reached values similar to the OGF. All other attributes, especially floristic composition, volume and biomass, had lower values than the OGF. Based on the aggregate set of attributes, the SDTF was 79 per cent recovered after 35 years of regeneration. The variance–covariance analysis indicated that species richness and aboveground biomass contributed the most to the aggregate ratio of regeneration, while maximum diameter and basal area contributed the least. Recovery of this semi-arid forest takes longer than recovery of other SDTF and requires more than 35 years of regeneration to return to a composition and structure similar to the original one. Therefore, management plans should restrict destructive uses before at least 35 years of regeneration have been reached.

Differentiating effects of salvage logging and recovery patterns on post-fire boreal forests in Northeast China using a modified forest disturbance index

ABSTRACT Forests are resilient to a range of disturbances, but combinations of severe natural and anthropogenic disturbances (e.g. wildfire and logging) may inhibit forest recovery and lead to forest degradation. Recent studies have explored long-term forest-disturbance detection and forest-recovery dynamics by using free and open-access remote-sensing images. However, mapping consecutive multiple disturbance agents is challenging using existing automated change-detection algorithms because the reduced canopy reflectance and the smoothing of consecutive disturbance signals mean that the initial disturbance cannot be spectrally separated from the second disturbance. Furthermore, uncertainty remains about post-disturbance vegetation dynamics and the effects of forest recovery under the interaction of burn severity, biological-legacy management, and active forest restoration (i.e. artificial regeneration and assisted natural regeneration). This contributes to biases in long-term forest-recovery monitoring, which are not conducive to the guidance of post-fire vegetation recovery. Here, we propose a modified disturbance index to separate the spectral characteristics of fire and forest logging using normalized tasseled-cap components (brightness and wetness) and detect the spatiotemporal distribution of post-fire logging by means of an index threshold and image differencing. On this basis, the recovery patterns of the post-fire forest are differentiated by considering the cumulative effect of fire, post-fire logging, and recovery approaches. The method is tested in the burn areas of the 5.6 Fire in the Greater Hinggan Mountain area (the largest forest fire in recorded history in China), giving an overall accuracy of 85% in post-fire forest logging mapping. Our results confirm that biological legacies (i.e. trees, logs, and snags) were removed across many areas in the fire, with activities peaking in the second year after the fire and located chiefly in areas of moderate and high burn severity. By identifying post-fire logging, the fluctuation and high disturbance index of the conventional temporal trajectory in the early stage of forest recovery are explained. The large-scale salvage logging slowed the recovery of the post-fire forest ecosystem and influenced the recovery process through the interaction of burn severity and active forest restoration. In areas of high burn severity, assisted natural regeneration (i.e. natural regeneration with artificial aids such as clearing the snags, weeding, digging pits, and supplemental planting) preserved biological legacies and achieved a higher proportion of forest recovery, second only to non-logged areas where natural regeneration (i.e. forestry recovering naturally without any artificial intervention) occurred. By contrast, salvage logging followed by artificial regeneration (i.e. clear-cutting all dead or damaged trees followed by tree planting or artificial seeding) hindered vegetation recovery in the early stage, but it improved the recovery rate in years 10–20 and approached the recovery proportion of non-logged areas where natural regeneration occurred as the recovery progressed and habitat conditions improved. The proposed method is shown to offer important advantages in detecting post-fire salvage logging, and it provides improved guidance for forest managers in developing strategies for forest recovery.

Short review of collecting technologies and methods in forest harvesting residues recovery

Tree felling and processing can create harvesting residues including leaves and twigs (needles), cones, barks, and branches. Collecting forest harvesting residues requires application of suitable machines and working methods. This article is aimed at reviewing the published reports to identify new harvesting machines and working methods for recovering harvesting residues and the current gaps. The scope of review included published research reports/articles from 2017 to 2022 (last five years). This global review results showed that popular methods for residue collection are chipping residues at roadside/landing and integrated biomass recovery. Forwarder, cable yarder and in-field chipper are predominantly applied within various recovery methods depending on ground and stand conditions. Harvesting residues are one of the promising sources for bioenergy production which requires developing efficient and low-cost harvesting systems. Latest research findings indicate that piling harvesting residues by a harvester-pro-cessor can improve the collecting productivity by the forwarder within cut-to-length harvesting opera-tions. Integrating residue biomass recovery with conventional timber supply can reduce the total supply chain cost by 2%. Researchers also recommend applying more climate-friendly technologies and focus-ing on developing new machines with lower fuel consumption and subsequent emissions. Future studies can focus on the following subjects; a) to determine the productivity and cost rates of various residue recovery systems, b) to develop and test technologies with lower fuel consumption rates and c) to find in-novative solutions to utilize thinning materials and best practices to store and process biomass materials.

Soil amelioration induced by nurse shrubs in coal mines reclaimed to pastures and their synergistic effects with grazing

Native shrubs facilitate the establishment of oak seedlings in the opencast coal mines rehabilitated to pastures in Northern Spain, under a Mediterranean sub-humid climate. We evaluate soil changes as one of the possible facilitative effects of nurse shrubs. We hypothesize that nurse shrubs on mining soils can improve edaphic properties directly and indirectly by reducing the negative effects of trampling and grazing by ungulates. Thus, we assessed the combined effects of nurse shrubs (plots with vs without shrubs) and grazing (plots with vs without a fence for preventing browsing and trampling) upon soil properties in a reclaimed coal mine. Chemical properties such as electrical conductivity, K+, cation exchange capacity, and C/N ratio reached higher values beneath shrubs’ canopies, so did total organic matter, total N, total organic C, total P, available P, and Mg2+ under shrubs but only with grazing. In contrast, pH was higher outside the shrubs; also Ca2+, though only in the absence of grazing. With grazing, Na+ decreased under shrubs. Among physical properties, bulk density increased and porosity decreased only in grazed plots, whereas sand content increased under shrubs in the grazed plots, and clay decreased in such locations. Water holding capacity and available water were the highest in ungrazed areas. Overall, we found that shrubs have a positive direct effect on soil fertility, especially relevant in grazed areas because nurse shrubs and grazing have synergistic effects, and a positive indirect effect on physical properties because they attenuate negative effects of grazing, particularly soil compaction, by reducing livestock and wild ungulates trampling. Therefore, these results demonstrate how nurse shrubs contribute to soil amelioration, helping to facilitate plant establishment in reclaimed mines, which has relevant restoration implications for pasture and forest recovery.

Disrupted montane forest recovery hinders biodiversity conservation in the tropical Andes

AbstractAimAndean montane forests are biodiversity hotspots and large carbon stores and they provide numerous ecosystem services. Following land abandonment after centuries of forest clearing for agriculture in the Andes, there is an opportunity for forest recovery. Field‐based studies show that forests do not always recover. However, large‐scale and long‐term knowledge of recovery dynamics of Andean forests remains scarce. This paper analyses tropical montane forest recovery trajectories over a 15‐year time frame at the landscape and tropical Andean scale to inform restoration planning.MethodsWe first detect “potential recovery” as areas that have experienced a forest transition between 2000 and 2005. Then, we use Landsat time series analysis of the normalized difference water index (NDWI) to classify four “realized recovery” trajectories (“ongoing”, “arrested”, “disrupted” and “no recovery”) based on a sequential pattern of 5‐yearly Z‐score anomalies for 2005–2020. We compare these results against an analysis of change in tree cover to validate against other datasets.ResultsAcross the tropical Andes, we detected a potential recovery area of 274 km2 over the period. Despite increases in tree cover, most areas of the Andes remained in early successional states (10–25% tree cover), and NDWI levelled out after 5–10 years. Of all potential forest recovery areas, 22% showed “ongoing recovery”, 61% showed either “disrupted” or “arrested recovery”, and 17% showed “no recovery”. Our method captured forest recovery dynamics in a Peruvian arrested succession context and in landscape‐scale tree‐planting efforts in Ecuador.Main conclusionsForest recovery across the Andes is mostly disrupted, arrested or unsuccessful, with consequences for biodiversity recovery and provision of ecosystem services. Low‐recovery areas identified in this study might be good candidates for active restoration interventions in this UN Decade on Restoration. Future studies could determine restoration strategies and priorities and suggest management strategies at a local planning scale across key regions in the biodiversity hotspot.

Orthophosphate fluxes in scattered trees from fragmented Andean landscapes highlight a biogeochemical role of foliar traits in pioneer species

AbstractHighly diverse neotropical ecosystems exhibit a natural limitation of phosphorus in the soil, sufficient to limit productivity and structure. This is more pronounced in Andean ecosystems, with high forest fragmentation and forest loss rates aggravating the effect. Previous studies have highlighted the importance of precipitation and its interaction with the canopy on nutrient inputs into forests. However, few studies have quantified the potential effects of structural and morphological tree diversity on the dynamics of phosphorous inputs on these ecosystems. In this study, we determined the association between 12 morphological plant functional traits and the movement of water‐driven orthophosphate from the canopy into the soil in 20 individuals of five tree species, on single individuals scattered across a human‐disturbed montane landscape in the Colombian Andes: Croton magdalenensis, Andesanthus lepidotus, Vismia baccifera and Quercus humboldtii and a commonly planted exotic species Eucalyptus globulus. We quantified PO4‐P concentrations in precipitation, throughfall and stemflow in all trees for 14 isolated rainfall events. In general, our results show a general enrichment of PO4‐P concentration in the net precipitation after passing through tree canopies. One particular species, C. magdalenensis, an ecological pioneer, had notably higher values of PO4‐P concentration. This condition relates, potentially, to a particularly higher epiphyte load, high leaf area and high trichome density. This condition potentially facilitates biogeochemical exchange and improves ecological functions associated with early stages of forest recovery (where pioneer species dominate forest composition). Our results are particularly relevant given that the highest contributions of PO4‐P to the soil occur in native species, which become key structures in the recovery of fragmented Andean ecosystems.

Monitoring Land Use/Land Cover and Landscape Pattern Changes at a Local Scale: A Case Study of Pyongyang, North Korea

One method of understanding landscape pattern changes is through an understanding of land use/land cover (LULC) changes, which are closely related to landscape pattern changes. Previous studies have monitored LULC changes across North Korea but did not consider landscape changes at a local scale. Using multiple LULC products to construct sample points, the LULC was classified using a random-forest algorithm and Landsat satellite dataset. The overall accuracy of the classification was 97.66 ± 1.36%, and the Kappa coefficient was 0.95 ± 0.03. Based on the classification results, landscape indices were used to quantify and monitor landscape pattern changes. The results showed that, from 2000 to 2020, there was an increasing trend in built-up and forest areas in Pyongyang, while cropland showed a decreasing trend, and landscape fragmentation increased. However, urban expansion was not the main factor affecting fragmentation. The main factors were forest recovery and cropland reduction, leading to an increase in landscape fragmentation in Pyongyang.

Four decades in fires research – A bibliometric analysis about the impact on mineralogy and nutrients

As wildfires have increased and become more frequent in recent years, researchers area focusing on how wildfires affect ecosystem resilience, which has serious implications for the recovery and protection of native forests and plantations. Most physicochemical and biological soil properties, including soil surface mineralogical composition, can be severely impacted by fires. However, no attempt has been made from a bibliometric point of view to provide a comprehensive picture of the research status on fire effects in mineralogy and nutrient stocks. Using the VOSviewer software, this study aims to evaluate fire effects on mineralogy and nutrients (FMN), the thematic evolution and determine the most relevant trends based on the intellectual structure of the knowledge built up in this research field. The methodology is divided into two stages: (i) Data Collection, and (ii) Bibliometric Analysis and Data Mining (Performance Analysis and Science Mapping). A detailed bibliometric analysis was performed on 530 Web of Science (WOS) articles indexes from1984 to 2020. Overall, the results show that Forest Ecology and Management is the leading journal in the field. The top three countries hosting core research centers for this topic are the United States, Spain, and France. Certini G. was the author with more citations (1395) in one paper and Johnson, D. had the most published papers (19) with a total of 549 citations. Currently, the hotspots of fire issues mainly include soil nutrients (e.g. nitrogen, phosphorus, carbon, and calcium); in addition to the selected keywords, wildfires co-occur more frequently with disturbances and terms such as soils, water quality, boreal forests, and stream. In conclusion, 530 articles written by 1822 authors and their research displayed in 211 journals from universities and research centers in 60 countries demonstrate the growing interest in the field.

Four-century history of land transformation by humans in the United States (1630–2020): annual and 1 km grid data for the HIStory of LAND changes (HISLAND-US)

Abstract. The land of the conterminous United States (CONUS) has been transformed dramatically by humans over the last four centuries through land clearing, agricultural expansion and intensification, and urban sprawl. High-resolution geospatial data on long-term historical changes in land use and land cover (LULC) across the CONUS are essential for predictive understanding of natural–human interactions and land-based climate solutions for the United States. A few efforts have reconstructed historical changes in cropland and urban extent in the United States since the mid-19th century. However, the long-term trajectories of multiple LULC types with high spatial and temporal resolutions since the colonial era (early 17th century) in the United States are not available yet. By integrating multi-source data, such as high-resolution remote sensing image-based LULC data, model-based LULC products, and historical census data, we reconstructed the history of land use and land cover for the conterminous United States (HISLAND-US) at an annual timescale and 1 km × 1 km spatial resolution in the past 390 years (1630–2020). The results show widespread expansion of cropland and urban land associated with rapid loss of natural vegetation. Croplands are mainly converted from forest, shrub, and grassland, especially in the Great Plains and North Central regions. Forest planting and regeneration accelerated the forest recovery in the Northeast and Southeast since the 1920s. The geospatial and long-term historical LULC data from this study provide critical information for assessing the LULC impacts on regional climate, hydrology, and biogeochemical cycles as well as achieving sustainable use of land in the nation. The datasets are available at https://doi.org/10.5281/zenodo.7055086 (Li et al., 2022).

Integrated approach to land management with self-sown forests in Ukraine

Protection and recovery of land natural ecosystems is a relevant task of sustainable development. Natural recovery of forests is an important instrument to solve the problem. The article describes the integrated approach to management of land use with self-sown forests, which have become a wide-spread phenomenon on the agricultural lands in Polissia and Forest-Steppe zones of the western Ukraine. The authors conducted an interview, which demonstrated people’s attitude to self-afforestation of lands. The idea of protecting self-sown forests was supported by one third of the respondents. Among those, who wish to possess a land plot with forests, the main share is represented by people of the age category of 21-40 years old. The authors substantiate the potential value of ecosystem services, which can be supplied by self-sown forests by introducing different practices. A focus is made on the ecosystem benefits from protection of self-sown forests, which cannot be expressed in money terms, but are of environmental and social value for the community. A model of integrated management of agricultural lands with self-sown forests was developed. It is suggested to use planning as an instrument, which involves assessment of the potential of land and other resources, to determine alternatives of land use, considering economic and social conditions of the territory development and landscape characteristics. Ukraine should develop a policy, establish institutes and approve procedures intended to protect self-sown forests. In the future, it will reduce the area of ploughed land and improve biodiversity of the territory.

Sunflower sea star predation on urchins can facilitate kelp forest recovery.

The recent collapse of predatory sunflower sea stars (Pycnopodia helianthoides) owing to sea star wasting disease (SSWD) is hypothesized to have contributed to proliferation of sea urchin barrens and losses of kelp forests on the North American west coast. We used experiments and a model to test whether restored Pycnopodia populations may help recover kelp forests through their consumption of nutritionally poor purple sea urchins (Strongylocentrotus purpuratus) typical of barrens. Pycnopodia consumed 0.68 S. purpuratus d-1, and our model and sensitivity analysis shows that the magnitude of recent Pycnopodia declines is consistent with urchin proliferation after modest sea urchin recruitment, and even small Pycnopodia recoveries could generally lead to lower densities of sea urchins that are consistent with kelp-urchin coexistence. Pycnopodia seem unable to chemically distinguish starved from fed urchins and indeed have higher predation rates on starved urchins owing to shorter handling times. These results highlight the importance of Pycnopodia in regulating purple sea urchin populations and maintaining healthy kelp forests through top-down control. The recovery of this important predator to densities commonly found prior to SSWD, whether through natural means or human-assisted reintroductions, may therefore be a key step in kelp forest restoration at ecologically significant scales.

Germination of shrub species from Chinese subtropical forests: implications for restoration.

Incorporating native shrubs into restoration projects can improve biodiversity conservation and enhance the sustainability of ecosystem functions. Shrubs grow under different forest canopy structures, having varied microclimatic conditions according to forest type and composition. Currently, there is a lack of information on propagation from seed and planting material availability for the utilization of shrubs in forest restoration. In the present study, we evaluated the effects of temperature and light on germination of ten shrub species (Ardisia japonica, Callicarpa cathayana, Callicarpa giraldii var. subcanescens, Deutzia schneideriana, Fraxinus sieboldiana, Hydrangea chinensis, Maesa japonica, Rhododendron simsii, Spiraea japonica var. fortunei and Weigela japonica var. sinica) occurring in subtropical forests in China. No seeds of any species germinated in the coolest thermal regime (5/10 °C), while optimal temperature requirements varied from 10/20 °C to 25/35 °C. Seeds of small-seeded species had higher germination percentages in the light treatments, while larger seeds were not photoblastic. There was no relationship between germination in the light and the seed shape index. Our results may assist in identification of seed traits and suitable shrub species for restoration in specific forest types, thus aiding native forest recovery of structure and composition. Successful recovery leads to enhanced biodiversity, reestablishment of microhabitats and ecological interactions in the forest understorey.

Effects of forest management practices on carbon dynamics of China's boreal forests under changing climates

Climate change and forest management practices influence forest productivity and carbon budgets, and understanding their interactions is necessary to develop accurate predictions of carbon dynamics as many countries in the world strive towards carbon neutrality. Here, we developed a model-coupling framework to simulate the carbon dynamics of boreal forests in China. The expected dynamics of forest recovery and change following intense timber harvesting in the recent past and projected carbon dynamics into the future under different climate change scenarios and forest management practices (e.g., restoration, afforestation, tending, and fuel management). We predict that under current management strategies, climate change would lead to increased fire frequency and intensity, eventually shifting these forests from carbon sinks towards being carbon sources. This study suggests that future boreal forest management should be altered to reduce the probability of fire occurrence and carbon losses caused by catastrophic fires through planting deciduous species, mechanical removal, and prescribed fire.

Stratification and recovery time jointly shape ant functional reassembly in a neotropical forest.

Microhabitat differentiation of species communities such as vertical stratification in tropical forests contributes to species coexistence and thus biodiversity. However, little is known about how the extent of stratification changes during forest recovery and influences community reassembly. Environmental filtering determines community reassembly in time (succession) and in space (stratification), hence functional and phylogenetic composition of species communities are highly dynamic. It is poorly understood if and how these two concurrent filters-forest recovery and stratification-interact. In a tropical forest chronosequence in Ecuador spanning 34 years of natural recovery, we investigated the recovery trajectory of ant communities in three overlapping strata (ground, leaf litter, lower tree trunk) by quantifying 13 traits, as well as the functional and phylogenetic diversity of the ants. We expected that functional and phylogenetic diversity would increase with recovery time and that each ant community within each stratum would show a distinct functional reassembly. We predicted that traits related to ant diet would show divergent trajectories reflecting an increase in niche differentiation with recovery time. On the other hand, traits related to the abiotic environment were predicted to show convergent trajectories due to a more similar microclimate across strata with increasing recovery age. Most of the functional traits and the phylogenetic diversity of the ants were clearly stratified, confirming previous findings. However, neither functional nor phylogenetic diversity increased with recovery time. Community-weighted trait means had complex relationships to recovery time and the majority were shaped by a statistical interaction between recovery time and stratum, confirming our expectations. However, most trait trajectories converged among strata with increasing recovery time regardless of whether they were related to ant diet or environmental conditions. We confirm the hypothesized interaction among environmental filters during the functional reassembly in tropical forests. Communities in individual strata respond differently to recovery, and possible filter mechanisms likely arise from both abiotic (e.g. microclimate) and biotic (e.g. diet) conditions. Since vertical stratification is prevalent across animal and plant taxa, our results highlight the importance of stratum-specific analysis in dynamic ecosystems and may generalize beyond ants.

Late-Holocene fynbos-forest dynamics in Orange Kloof, Table Mountain National Park, South Africa

Fynbos and afrotemperate forest exist as alternate stable states in the Cape Floristic Region of South Africa. In parts of Table Mountain National Park, afrotemperate forest has expanded in recent decades. The aim of this project was to explore the drivers of this change and distinguish whether this expansion represents a recovery of forest after previous clearance during the 18th century or is a novel expansion of forest range that resulted from policies of fire suppression in the 20th century. To determine the relationships between forest and fynbos and its key drivers, pollen, non-pollen palynomorphs, charcoal, stable isotope ratios (δ13C) and major and trace elements were analysed from late-Holocene sediments extracted from Orange Kloof. Pollen data show that forest cover has fluctuated over the past 3690 years. At the start of the record, under drier conditions from 1670 BCE to ~170 CE, forests contracted, and dry, asteraceous fynbos dominated the landscape. Around ~170 CE there was a shift to ericaceous fynbos as water availability increased. Weak signals of Khoekhoen pastoralists may be visible in the record around 50 CE, indicated by increased spores and charcoal. A regime shift towards increased dominance of the forest occurred ~250 CE, associated with wetter climate. Clear anthropogenic signals are associated with European settlement from 1650 CE. Reinforced by human clearance of forest, fynbos expanded during the cool conditions of the late phase of Little Ice Age (~1750–1850 CE). Forest expansion in the 20th century likely reflects fire suppression and recovery from past forest clearance. Fire needs to be managed accordingly if further expansion of forest into fynbos is to be curbed.

Phosphorus adsorption in a degraded soil under forestry recovery after bauxite mining in Paragominas, eastern Amazon, Brazil

AbstractThe availability and retention of phosphorus (P) in soils under recovery process after mining operations play an important role in the management of this nutrient. The objective of this study was to evaluate the P adsorption in a reconstituted soil as a function of two forest recovery processes after bauxite mining. We evaluated three systems: native forest (FOR), planting of forest seedlings after bauxite mining (TPL), and natural regeneration of vegetation after bauxite mining (NRV). In each system, eight sampling plots were deployed. In each plot, we collected litter and soil samples. The soil samples were collected at depths of 0–5, 5–10, 10–20, and 20–40 cm, for soil chemical analysis and adjustment of P adsorption isotherms. We also performed an inventory of the tree vegetation to obtain basal area (G) and species diversity (H′). Forest was significantly superior with respect to most soil fertility, litter, and vegetation attributes, followed by natural regeneration and planting. In general, the adsorption curves and maximum phosphorus adsorption capacity (MPAC) in soil followed the order planting > natural regeneration > forest. We observed a negative relationship between phosphorus adsorption and soil organic matter, potential acidity, and available phosphorus. This result highlights the importance of biomass conservation and maintenance to ensure phosphorus availability in reclamation practices. Furthermore, such results indicate that both soil cover and plant species diversity should be considered when selecting species to improve P availability for reclamation of mined areas.

Twenty-Seven Year Response of South Carolina Coastal Plain Forests Affected by Hurricane Hugo.

In 1989, Hurricane Hugo inflicted catastrophic damage on approximately 1.8 million ha of forested land in South Carolina. The purpose of this study was to monitor species compositional shifts and structural changes in several forest types following the hurricane's disturbance. The immediate consequences of hurricane damage are well documented, but there are few studies based on the long-term compositional and structural changes that may result from hurricane disturbance, especially in temperate forest ecosystems. Forty-two forested plots were monitored within four study areas that received varying degrees of hurricane damage. Inventories included species, damage class, tree diameter, and regeneration. The objectives of this study were (1) to compare the recovery speed of wetland forests (e.g., bottomland hardwood swamps and cypress-tupelo swamps) to that of upland pine and hardwood forests; (2) to discover how the degree of hurricane damage can affect the timing and the pattern of forest recovery in the coastal plain; and (3) to compare individual species response patterns across different forest types and at different levels of initial damage. Over the 27-year period following the hurricane, successional pathways have been variable among plots of different forest types and intensity of initial disturbance. We have observed an expected increase in basal area (BA) following the disturbance. Sapling populations in many species have increased dramatically, and some of these populations have begun to thin in recent years. In several forest types, loblolly pine (Pinus taeda L.-not a predominant species in these sites prior to the hurricane) responded quickly and overtook some dominant species in BA and tree/sapling abundance. Several other species that were not a major component of the tree strata (wax myrtle [Morella cerifera (L.) Small], green ash [Fraxinus pennsylvanica Marsh.], and the invasive Chinese tallow [Triadica sebifera (L.) Small]) showed a large increase in sapling population. Overall, recovery speed and species resilience were specific to forest types and damage severity. The intensity and frequency of hurricanes may increase in the future as sea surface temperatures rise. Understanding how coastal forests respond to major hurricanes in the short-term and the long-term will aid us in preparing for future hurricanes and for potential changes in disturbance regimes.

Mapping Land Use/Land Cover Changes and Forest Disturbances in Vietnam Using a Landsat Temporal Segmentation Algorithm

Accurately mapping land use/land cover changes (LULCC) and forest disturbances provides valuable information for understanding the influence of anthropogenic activities on the environment at regional and global scales. Many approaches using satellite remote sensing data have been proposed for characterizing these long-term changes. However, a spatially and temporally consistent mapping of both LULCC and forest disturbances at medium spatial resolution is still limited despite their critical contributions to the carbon cycle. In this study, we examined the applicability of Landsat time series temporal segmentation and random forest classifiers to mapping LULCC and forest disturbances in Vietnam. We used the LandTrendr temporal segmentation algorithm to derive key features of land use/land cover transitions and forest disturbances from annual Landsat time series data. We developed separate random forest models for classifying land use/land cover and detecting forest disturbances at each segment and then derived LULCC and forest disturbances that coincided with each other during the period of 1988–2019. The results showed that both LULCC classification and forest disturbance detection achieved low accuracy in several classes (e.g., producer’s and user’s accuracies of 23.7% and 78.8%, respectively, for forest disturbance class); however, the level of accuracy was comparable to that of existing datasets using the same reference samples in the study area. We found relatively high confusion between several land use/land cover classes (e.g., grass/shrub, forest, and cropland) that can explain the lower overall accuracies of 67.6% and 68.4% in 1988 and 2019, respectively. The mapping of forest disturbances and LULCC suggested that most forest disturbances were followed by forest recovery, not by transitions to other land use/land cover classes. The landscape complexity and ephemeral forest disturbances contributed to the lower classification and detection accuracies in this study area. Nevertheless, temporal segmentation and derived features from LandTrendr were useful for the consistent mapping of LULCC and forest disturbances. We recommend that future studies focus on improving the accuracy of forest disturbance detection, especially in areas with subtle landscape changes, as well as land use/land cover classification in ambiguous and complex landscapes. Using more training samples and effective variables would potentially improve the classification and detection accuracies.