Forest Conversion Research Articles

Soil microbiome feedbacks during disturbance-driven forest ecosystem conversion.

Disturbances cause rapid changes to forests, with different disturbance types and severities creating unique ecosystem trajectories that can impact the underlying soil microbiome. Pile burning-the combustion of logging residue on the forest floor-is a common fuel reduction practice that can have impacts on forest soils analogous to those following high-severity wildfire. Further, pile burning following clear-cut harvesting can create persistent openings dominated by nonwoody plants surrounded by dense regenerating conifer forest. A paired 60-year chronosequence of burn scar openings and surrounding regenerating forest after clear-cut harvesting provides a unique opportunity to assess whether belowground microbial processes mirror aboveground vegetation during disturbance-induced ecosystem shifts. Soil ectomycorrhizal fungal diversity was reduced the first decade after pile burning, which could explain poor tree seedling establishment and subsequent persistence of herbaceous species within the openings. Fine-scale changes in the soil microbiome mirrored aboveground shifts in vegetation, with short-term changes to microbial carbon cycling functions resembling a postfire microbiome (e.g. enrichment of aromatic degradation genes) and respiration in burn scars decoupled from substrate quantity and quality. Broadly, however, soil microbiome composition and function within burn scar soils converged with that of the surrounding regenerating forest six decades after the disturbances, indicating potential microbial resilience that was disconnected from aboveground vegetation shifts. This work begins to unravel the belowground microbial processes that underlie disturbance-induced ecosystem changes, which are increasing in frequency tied to climate change.

Rapid recovery of ant-mediated seed dispersal service along secondary succession in a Caatinga dry forest

Global expansion of secondary forests results from old-growth forest conversion to agriculture and livestock fields, followed by abandonment. Dry forests heavily rely on resprouting for rapid biomass recovery, but some species depend on seed dispersers. Ants are important seed dispersers in dry forests, as they can transport seeds over long distances, help species join the soil seed bank, and promote seed germination and seedling recruitment. We investigated seed-dispersing ant community, ant-seed interactions, and seed removal rates and distances along a Caatinga dry forest secondary succession using forest stands (8–54 years) after slash-and-burn agriculture and old-growth forest stands. We observed 796 interactions with 29 ant species and four plant species. About 26.51% were removals by 12 ant species, notably Dinoponera quadriceps and Ectatomma muticum, dispersing seeds up to 15 m. Only 14% of removed seeds reached nests while the rest were lost along foraging trails. Ant abundance of seed-dispersing ant community increased significantly with forest aboveground biomass, and both ant abundance and richness were significantly higher in secondary forest stands. Ant-seed interactions increased with biomass, being higher in old-growth forests. However, ant community composition, removal rates, and dispersal distances remained consistent across biomass and forest types. These findings may suggest that ant-mediated seed dispersal service quickly recovers during secondary succession, with implications for the dynamics of forest regeneration, given that ant-mediated seed dispersal is a prevalent and widespread phenomenon in the Caatinga dry forest.

Fine-Root Distribution and Soil Physicochemical Property Variations in Four Contrasting Urban Land-Use Types in South Korea.

Urbanization and associated forest conversions have given rise to a continuum of native (forest fragments) and modified (artificial grasslands and perennial ecosystems) land-use types. However, little is known about how these shifts affect soil and fine-root compartments that are critical to a functioning carbon and nutrient circulation system. In this study, soil physicochemical properties, fine-root mass, and vertical distribution patterns were investigated in four representative urban land-use types: grassland (ZJ), perennial agroecosystem (MP), broadleaf deciduous forest patch (QA), and coniferous evergreen forest patch (PD). We quantified the fine-root mass in the upper 30 cm vertical profile (0-30 cm) and at every 5 cm depth across three diameter classes (<2 mm, 2-5 mm, and <5 mm). Soil physicochemical properties, except for phosphorus, nitrogen, ammonium nitrogen, and sodium cations, varied significantly across land-use types. The total root biomass (<5 mm) decreased in the order of QA (700.3 g m-2) > PD (487.2 g m-2) > ZJ (440.1 g m-2) > MP (98.3 g m-2). The fine-root mass of ZJ and MP was correlated with soil nutrients, which was attributed to intensive management operations, while the fine-root mass of QA and PD had a significant relationship with soil organic matter due to the high inputs from forest litter. Very fine roots (<2 mm) presented a distinct decremental pattern with depth for all land-use types, except for MP. Very fine roots populated the topmost 5 cm layer in ZJ, QA, and PD at 52.1%, 49.4%, and 39.4%, respectively. Maintaining a woody fine-root system benefits urban landscapes by promoting soil stabilization, improving ground infiltration rates, and increasing carbon sequestration capacity. Our findings underscore the importance of profiling fine-root mass when assessing urban expansion effects on terrestrial ecosystems.

Phosphorus speciation under long‐term crop rotation management in a tropical soil

AbstractCrop rotation and soil management practices after native tropical forest conversion may impact the dynamics of inorganic and organic phosphorus (Pi and Po) species in the soil. By combining the state‐of‐the‐art spectroscopic methods P K‐edge X‐ray absorption near edge structure (XANES), 31P liquid nuclear magnetic resonance (31P‐NMR) and chemical P fractionation, this study provides important insights on soil P speciation after conversion of native forest to cropland under distinct managements. A field trial was conducted in a weathered tropical soil to assess Pi and Po changes after conversion of native forest to cropland. The crop rotations were managed under no‐tillage (NT) or minimum tillage (MT) since 2003, and repeated annually until 2015, cropped in the fall–winter and spring seasons, followed by soybean in the summer. Soil XANES analysis in the end revealed that P was predominantly associated with ferrihydrite and hematite, suggesting that P speciation was more strongly influenced by the presence of iron(oxyhydr)oxide than by crop rotations and/or soil management. The conversion of native forest to cropland promoted the mineralization of Po species, leading to re‐adsorption in non‐labile forms and consequently worsening the P cycling in the system. To increase the labile P pools and supply crop P demand, inputs of inorganic fertilizers were required owing to the strong soil P sorption. Our results show that even conservation practices such as MT or NT and complex crop rotations are not sufficient to inhibit the impact of cropland conversion on soil P forms.

Does Globalization Matter for Rainforest Degradation? Nexus among Economic Performance, Forest Conversion and Biomass Consumption

Does Globalization Matter for Rainforest Degradation? Nexus among Economic Performance, Forest Conversion and Biomass Consumption

Soil microbial community structure and soil fertility jointly regulate soil microbial residue carbon during the conversion from subtropical primary forest to plantations

Soil microbes mediate soil organic carbon (SOC) storage by affecting microbial residue carbon (C) in terrestrial ecosystems, a main source of SOC. However, how microbial residue C accumulation changes during the conversion of subtropical primary forest to plantations and the role of soil microbial community structure in regulating these changes remain unclear. Here, effects of conversion from forest on microbial residue C accumulation in three plantations, including tea (Camellia sinensis var. assamica), walnut (Juglans regia), and macadamia (Macadamia integrifolia). We assessed amino sugars content and the relative importance of soil microbial community structure, soil fertility, and aboveground biomass in four forest types in southwest Yunnan province, China. Our results show that total microbial residue C accounted for 27.8 % of SOC on average across all forest types, and fungal residue C contributed more to SOC than bacterial residue C across different forest types. Conversion from primary forest decreased fungal, bacterial, and total microbial residue C content in all plantation types except tea. Microbial residue C contents was significantly lower in the macadamia plantation than in the primary forest and the tea plantation. Fungal and total microbial residue C content increased with increasing soil microbial community composition, soil fungal abundance, and soil fertility. Soil fertility regulated fungal, bacterial, and total microbial residue C accumulation, which was major determinant of microbial residue C via its influence on soil fungal and bacterial abundance. Overall, we found that soil fungal abundance contributed more to microbial residue C accumulation than change in soil microbial community composition. We also found that soil bacterial abundance was negatively correlated with fungal and microbial residue C, while soil fungal abundance was positively related to microbial residue C accumulation. Ascomycota was most important phylum regulating microbial residue C. These findings suggest that soil fungal and bacterial abundance and soil fertility are the principal regulators of microbial residue C accumulation during the conversion from primary forest to different plantations.

The differential impacts of the spatiotemporal vertical and horizontal expansion of megacity Dhaka on ecosystem services

The relationship between ecosystem services (ES) and urbanization is crucial for sustainable development. Rapid urbanization threatens the natural capital of Dhaka city, affecting the delivery of ES through changes in land use and land cover. We used vertical growth (VG), nighttime light data (NTL), and population density (PD) as standard urbanization indicators alongside technomass, a three-dimensional indicator, to evaluate the degree of urbanization as a continuous spatial process. We modeled the spatiotemporal relationships between urbanization degrees and ES using the ecosystem service value (ESV) dataset applied in Dhaka, with regional modified value coefficients. Results from the geographically weighted regression (GWR) model showed that technomass emerged as a more appropriate indicator to analyze urbanization for ESV analysis (r > 0.61), followed by NTL (r > 0.56), and PD (r > 0.54) across all zones from 2000 to 2021. We observed a 68.34% decrease in net ESV, equivalent to $245.88 million (in 2021 USD), from 2000 to 2021. This decline was driven by the conversion of water bodies (−70.93%), agricultural land (−60.08%), forest and vegetation (−70.18%) into urban built-up areas and other uses. In contrast, net technomass increased by 243.11% due to the city's vertical growth. The digital building height (DBH) model revealed that the built-up area had expanded by 94.94% over the study period, with an average annual growth rate of 4.52%. Significant correlations (p < 0.05) were observed between ES and urbanization. The rural-urban fringe area exhibited the most significant increase in urbanization (r > 0.90), along with a 440.47% growth in technomass. Our results provide insights into the impact of urbanization on ES, particularly at the regional scale, and have highlighted the importance of integrating VG and technomass for urbanization analysis. These findings could be useful for environmental management, policymaking, spatial planning, and coordinating future ES protection and urban development.

Analyzing Land Use/Land Cover Changes Using Google Earth Engine and Random Forest Algorithm and Their Implications to the Management of Land Degradation in the Upper Tekeze Basin, Ethiopia.

Land use and land cover change (LULCC) without appropriate management practices has been identified as a major factor contributing to land degradation, with significant impacts on ecosystem services and climate change and hence on human livelihoods. Therefore, up-to-date and accurate LULCC data and maps at different spatial scales are significant for regular monitoring of existing ecosystems, proper planning of natural resource management, and promotion of sustainable regional development. This study investigates the temporal and spatial dynamics of land use land cover (LULC) changes over 31 years (1990-2021) in the upper Tekeze River basin, Ethiopia, utilizing advanced remote sensing techniques such as Google Earth Engine (GEE) and the Random Forest (RF) algorithm. Landsat surface reflectance images from Landsat Thematic Mapper (TM) (1990, 2000, and 2010) and Landsat 8 Operational land imager (OLI) sensors (2021) were used. Besides, auxiliary data were utilized to improve the classification of LULC classes. LULC was classified using the Random Forest (RF) classification algorithm in the Google Earth Engine (GEE). The OpenLand R package was used to map the LULC transition and intensity of changes across the study period. Despite the complexity of the topographic and climatic features of the study area, the RF algorithm achieved high accuracy with 0.83 and 0.75 overall accuracy and Kappa values, respectively. The LULC change results from 1990 to 2021 showed that forest, bushland, shrubland, and bareland decreased by 12.2, 24.8, 1.2, and 15.4%, respectively. Bareland has changed to farmland, settlement, and dry riverbed and stream channels. Expansion of dry stream channels and sandy land surfaces has been observed from 1990 to 2021. Bushland has shown an increment by 17.2% from 1900 to 2010 but decreased by 19.5% from 2010 to 2021. Throughout the study period, water, farmland, dry stream channels and riverbeds, and urban settlements showed positive net gains of 484, 8.7, 82, and 26778.5%, respectively. However, forest, bush, shrub, and bareland experienced 12.17, 24.8, 1.2, and 15.37% losses. The observed changes showed the existing land degradation and the future vulnerability of the basin which would serve as an evidence to mitigate land degradation by avoiding the future conversion of forest, bushland, and shrubland to farmland, on the one hand, and by scaling up sustainable farmland management, and afforestation practices on degraded and vulnerable areas, on the other hand.

Drivers of tree regeneration in coniferous monocultures during conversion to mixed forests in Central Europe – Implications for forest restoration management

In Central Europe, anthropogenic coniferous monocultures have been subject to conversion to more diverse mixed forests since the 1990s, however, they are still abundant across many forest landscapes. Artificial and natural tree regeneration both play a key role during conversion by determining the species composition and structure of the future forests. Many abiotic and biotic factors can potentially influence the regeneration process and its specific combinations or interactions may be different among tree species and its developmental stages. Here, we aimed to identify and quantify the effect of the most important drivers on the density of the most abundant regenerating tree species (i.e., Norway spruce and European beech), as well as on species and structural diversity of the tree regeneration. We studied tree regeneration in four former monospecific coniferous stand types (i.e., Norway spruce, Scots pine, European larch, and Douglas fir) in Southwest Germany that have been under conversion to mixed forests since the 1990s. We sampled tree regeneration in four growth height classes together with a variety of potentially influencing factors on 108 sampling plots and applied multivariate analyses. We identified light availability in the understorey, stand structural attributes, browsing pressure, and diaspore source abundance as the most important factors for the density and diversity of tree regeneration. Particularly, we revealed species-specific differences in drivers of regeneration density. While spruce profited from increasing light availability and decreasing stand basal area, beech benefited either from a minor reduction or more strikingly from an increase in overstorey density. Increasing diaspore source abundance positively and a high browsing pressure negatively affected both species equally. Our results suggest that humus and topsoil properties were modified during conversion, probably due to changes in tree species composition and silvicultural activities. The species and structural diversity of the tree regeneration benefitted from increasing light availability, decreasing stand basal area, and a low to moderate browsing pressure. We conclude that forest managers may carefully equilibrate among the regulation of overstorey cover, stand basal area, and browsing pressure to fulfil the objectives of forest conversion, i.e., establishing and safeguarding a diverse tree regeneration to promote the development of mature mixed forests in the future.

Land management of formerly subtropical Atlantic Forest reduces soil carbon stocks and alters microbial community structure and function

Soil carbon (C) sequestration has been proposed as one means to mitigate the effects of climate change and to guarantee food safety. However, forest conversion to managed land uses can deplete soil C stocks and affect soil microbial communities, potentially impacting a wide range of ecosystem services. Our objective was to investigate the effect of forest conversion to intensive land uses on soil C dynamics and soil microbial community structure and function in the subtropical portion of the Atlantic Forest biome. We evaluated four land uses - forest fragment, grassland, and agriculture with five or fifty years of cultivation. We analyzed soil C pools, edaphic variables, and soil bacterial/archaeal (16S) and fungal (ITS) communities. Forest conversion to managed land uses reduced soil C stocks and altered soil microbial community structure, with implications for soil C dynamics. Bacterial/archaeal and fungal community composition were strongly correlated with pH, base saturation, and calcium (Ca) and magnesium (Mg) content. However, soil C pools were not associated with potential extracellular enzyme activity or microbial diversity. Finally, the fungal species Mortierella minutissima ASV_1 and several bacterial groups were positively correlated with soil C stocks, potentially representing indicators of soil C storage. Our study indicates that land use change affects the interplay between soil microbial communities and soil C pools, with consequences to soil C storage. Our findings may support the development of soil C enhancement programs within the Atlantic Forest biome.

Mudanças de uso da terra e emissão de gases de efeito estufa: uma explanação sobre os principais drivers de emissão

Abstract Global warming is attributed to the increase in greenhouse gas (GHG) emissions, such as carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). Land use changes significantly impact on GHG emissions, accounting for approximately 44% of the country’s emissions in 2019. This review addresses the main pathways of GHG formation in the soil, focusing on the influence of land use changes on GHG emissions. It is found that soil CO2 emissions are related to root respiration, microorganisms, and organic matter (OM) decomposition in the soil. Changes in land use can alter soil characteristics, favoring increased CO2 emissions. Soil CH4 emissions occur under anaerobic conditions by methanogenic microorganisms; however, land use changes, such as forest conversion to pasture, can increase CH4 emissions due to a higher concentration of methanogenic microorganisms in the soil. On the other hand, N2O is produced in the soil during nitrification and denitrification processes by microorganisms, and nitrogen fertilization in agricultural areas can increase N2O emissions, especially when associated with soil moisture and the availability of organic carbon. It is important to understand the dynamics of GHG formation and emissions resulting from land use changes because efficient management strategies can reduce these emissions and contribute to Brazil’s goals for GHG reduction as established in international agreements.

Conversion of tropical secondary forest into agricultural land: consequences for soil health and environmental stability

The objective of the study was to address the impacts of tropical forest conversion into agricultural land on changes in invertebrates’ communities, as well as soil chemical properties across 2–4 texturally distinct soils in La Mé and Grand Lahou, Côte d’Ivoire. The fieldwork was carried out in the humid period on two study sites: 1– rubber landscape (secondary forest, 7-, 12- and 25-year-old rubber plantations) and 2– oil palm landscape (secondary forest, 13-, 20- and 39-year-old oil palm plantations). Three sampling stands were established on each land-use type and age class, for a total of 24 sampling stands. Over a 40–50 m transect, topsoil (0–10 cm) invertebrates were sampled by using monoliths (50 cm × 50 cm × 10 cm), following the modified ‘Tropical soil biology and fertility’ method. Soils chemical properties were also determined. The results highlighted a decrease in taxonomic richness (–35 % and –42 %), Shannon index (–32 % and –37 %), Margalef index (–34 % and –41 %), soil carbon stock (–41 % and –15 %), nitrogen stock (–38 % and –11 %) and carbon sequestration (–41 % and –15 %), respectively, after the transformation of secondary forests into rubber and oil palm plantations. The clay soils and clay sandy soils favored the development and emergence of the soil invertebrates, and allowed a higher carbon and nitrogen storage, as well as a greater carbon sequestration. Whatever the site, the soil quality was more degraded under the monoculture tree plantations compared to the secondary forests. Our findings suggest leaving residues of the previous crop on the soil surface and the incorporation of woody trees with an understory of smaller trees during the early establishment periods of monoculture tree plantations, which can create a sustainable agroforestry system with improved nutrient recycling and soil fertility.

Land use/cover change and transormations in Upper Runde Sub-catchment area in Zimbabwe

The study assessed land use/cover changes in the Upper Runnde sub-catchment in Zimbabwe between 2000 and 2020 using GIS and remote sensing techniques with the support of interviews and field observations. Faster land use/cover changes were experienced within the 2000–2010 decade when compared to the 2010–2020 decade; for instance, bare land increased by 92.1% between 2000–2010 compared to 16.5% between 2010–2020. Major land cover transformations included change from forest land to bare land, grassland and shrub land, and change from grassland to bare and shrub land to grassland. The results confirmed conversion of forests to agricultural lands and settlements following the fast-track land reform program in 2000, and livestock increase induced overgrazing as major human activities driving land cover changes. There is a need for serious attention from resource management stakeholders before depletion of critical resources like water and woodlands. Therefore, the Ministry of Lands, Agriculture, Water, and Rural Resettlement and the Zimbabwe National Water Authority may consider strict auditing of land uses and water resource use in catchment areas to guard against encroachment of agriculture and other land uses in protected lands and fragile ecosystems like water bodies and wetlands.

Can REDD+ succeed? Occurrence and influence of various combinations of interventions in subnational initiatives

The institutional predecessor of REDD+ is the integrated conservation and development project (ICDP) that combines restrictions on forest access and conversion (negative interventions) withnon-conditionaldirect benefits (positive interventions) to compensate local stakeholders for income losses from those restrictions. The idea of REDD+ was to improve on the ICDP model with a different kind of positive intervention:conditional direct benefits, often known as payments for environmental services or PES. How has this idea played out in reality? In a sample of 17 (out of 377) active REDD+ initiatives across the global South, we identified the combinations of interventions actually deployed and elicited household assessments of how those interventions affected their land use decisions with respect to forests. We found that 71 % of the households in our sample had participated in some number of forest interventions ranging from one to ten. About a quarter of those households were offered conditional direct benefits, most often in combination with non-conditional direct benefits. Nearly half of the households had received only non-conditional direct benefits. Many of those households were also subject to restrictions of various kinds. Thus, rather than abandoning the well-established ICDP approach in favor of the conditional incentives that conceptually define REDD+, most initiative proponents opted to deploy multiple interventions. Their approach is validated by our finding that the likelihood a household reports that the interventions caused them to adopt land use changes that could be classified as reducing carbon emissions is positively and significantly related to the number of interventions that they experienced, but not affected by whether any of those interventions are conditional. We also find that restrictions play an important role: 37 % of the households were subject to at least one negative intervention, and those households were significantly more likely to report that the interventions had induced land use changes that could be classified as reducing carbon emissions.

Driving factors of tree biomass and soil carbon pool in xerophytic forests of northeastern Argentina

BackgroundThe conversion of forests into agricultural lands can be a threat because the forests carbon stored could be a source of emissions. The capacity to improve the predictions on the consequences of land use change depends on the identification of factors that influence carbon pools. We investigated the key driving factors of tree biomass and soil carbon pools in xerophytic forests in northeastern Argentina. Based on analyses of forest structure variables and abiotic factors (topography and soil properties) from 18 mature forests, we evaluated carbon pools using uni- and multivariate (redundancy analysis) methods.ResultsThe total carbon pool was estimated at 102.4 ± 24.0 Mg ha−1. Soil organic carbon storage is the single largest carbon pool relative to tree biomass, representing 73.1% of total carbon. Tree canopy cover and basal area were positively correlated with biomass carbon pool (r = 0.77 and r = 0.73, p < 0.001, respectively), proving to be significant drivers of carbon storage in this compartment. Slope, soil clay content and cation-exchange capacity had a better explanation for the variability in soil carbon pools, and all showed significant positive correlations with soil carbon pools (r = 0.64, 0.60 and 0.50; p < 0.05, respectively). The vertisols showed a 27.8% higher soil carbon stock than alfisols.ConclusionsThe relevance of our study stems from a dearth of information on carbon pools and their drivers in xerophytic forests, and in particular, the importance of this ecosystems’ type for Argentina, because they cover 81.9% of native forest area. Basal area and tree canopy cover exert a strong effect on the carbon pool in tree biomass but not in the soil. The results suggests that there is a potentially major SOC accumulation in forests located in slightly sloping areas and soils with higher topsoil clay content, such as vertisols. This could provide an important reference for implementing forestry carbon sink projects.

Effects of the forests-agriculture conversion on the availability and diversity of forest products in a neotropical rainforest region

Tropical rainforests offer a diverse array of real or potential forest products (FP). However, the ongoing conversion of these forests to agriculture raises concerns about the future availability and sustainability of FP. In this study, we examined the changes in availability (tree density and above-ground biomass) and species richness of native trees, recognized by local communities as sources of FP, with the forest-to-agriculture conversion in a Mesoamerican tropical rainforest region. Specifically, we tested hypotheses on whether species with FP had a higher, equal, or lower reduction in the availability, diversity, and probability of persistence than species without FP with the forest conversion. We interviewed landowners to identify tree species with FP and documented management practices and regulations for using these species. In fourteen 1 km2 landscapes, encompassing the entire range of forest-to-agriculture conversion (from 0 % to ∼100 % old-growth forest cover), we analyzed changes in the availability and richness of species with and without FP. In each landscape, we randomly established 30 plots (each 706.8 m2, totaling 420 plots and 29.7 ha sampling area) covered by old-growth forest, secondary forest, or agricultural fields (mostly cattle pastures). Over four years, we surveyed all trees with a diameter at breast height ≥ 10 cm in these plots. With the forest conversion, assemblages of tree species with FP exhibited a higher reduction in aboveground biomass than species without FP. However, assemblages of species with FP exhibited a significantly lower reduction in abundance, species richness, and a higher probability of persistence than assemblages of species without FP. Furthermore, we found evidence of implementing forest management practices favoring the preservation of species with FP in agricultural lands. Thus, we conclude that people intentionally foster the persistence of valuable species in their agricultural fields, which could have important implications for the structure and composition of future regenerating forests on abandoned agricultural lands. In the long term, this might lead to an overabundance of locally valuable species, as observed in old-growth tropical rainforests that native people ancestrally managed.

Soil phosphorus cycling across a 100-year deforestation chronosequence in the Amazon rainforest.

Deforestation of tropical rainforests is a major land use change that alters terrestrial biogeochemical cycling at local to global scales. Deforestation and subsequent reforestation are likely to impact soil phosphorus (P) cycling, which in P-limited ecosystems such as the Amazon basin has implications for long-term productivity. We used a 100-year replicated observational chronosequence of primary forest conversion to pasture, as well as a 13-year-old secondary forest, to test land use change and duration effects on soil P dynamics in the Amazon basin. By combining sequential extraction and P K-edge X-ray absorption near edge structure (XANES) spectroscopy with soil phosphatase activity assays, we assessed pools and process rates of P cycling in surface soils (0-10 cm depth). Deforestation caused increases in total P (135-398 mg kg-1 ), total organic P (Po ) (19-168 mg kg-1 ), and total inorganic P (Pi ) (30-113 mg kg-1 ) fractions in surface soils with pasture age, with concomitant increases in Pi fractions corroborated by sequential fractionation and XANES spectroscopy. Soil non-labile Po (10-148 mg kg-1 ) increased disproportionately compared to labile Po (from 4-5 to 7-13 mg kg-1 ). Soil phosphomonoesterase and phosphodiesterase binding affinity (Km ) decreased while the specificity constant (Ka ) increased by 83%-159% in 39-100y pastures. Soil P pools and process rates reverted to magnitudes similar to primary forests within 13 years of pasture abandonment. However, the relatively short but representative pre-abandonment pasture duration of our secondary forest may not have entailed significant deforestation effects on soil P cycling, highlighting the need to consider both pasture duration and reforestation age in evaluations of Amazon land use legacies. Although the space-for-time substitution design can entail variation in the initial soil P pools due to atmospheric P deposition, soil properties, and/or primary forest growth, the trend of P pools and process rates with pasture age still provides valuable insights.

Tight relationships between leaf and topsoil stoichiometries after 42 years of forest conversion from old-growth forests to Chinese fir plantations

Soil C:N:P stoichiometry can regulate plant survival and reflect soil fertility and nutrient utilization. Despite the widespread conversion of old-growth forests to plantations or secondary forests, there is little knowledge about how these conversions affect the relation between leaf and soil stoichiometries. We examined the topography, leaf, and soil stoichiometries of 75 plots (20 m × 20 m) across Chinese fir plantations, secondary forests, and old-growth forests in subtropical China. We found that: (1) There were significant differences in leaf carbon, nitrogen, phosphorus, and their stoichiometry ratios among different stand types (2) stand type significantly affected soil SOC, TP, C:N, C:P, and N:P, except TN and (3) the explanation percentage of leaf stoichiometry on soil stoichiometry doubled with the conversion of old-growth forest to Chinese fir plantation, whereas it was twofold decreased with the conversion of old-growth forest to secondary forest. The explanation percentage of topography on soil stoichiometry decreased onefold at a minimum with the conversion of the old-growth forest to the Chinese fir plantation or the secondary forest. Our results show the shortages of soil nutrients from transforming old-growth forests into plantations or secondary forests and indicate the urgent need to preserve the remaining old-growth forests and increase stand ages by reducing forest disturbances. Therefore, determining the optimal stand type and slope location can effectively promote the accumulation of carbon, nitrogen, and phosphorus nutrients in the topsoil, which is essential for improving the planning and implementation of appropriate forest restoration and ecosystem management strategies.

Could private land reserves in Brazil’s Amazon be a viable conservation strategy for forest protection? An overview of the challenges and opportunities

This paper identifies Reservas Particulares do Patrimônio Natural, a Brazilian legal land use distinction, as an enabling framework for investment and sustainable development. Brazilian Amazon rainforest contains private land but is a threatened and undervalued public good which humanity needs for climate stability, human health, and cultural and natural heritage. Amazon land use strategy over the last 50 years has divided between strict conservation on public lands that allows nearly no economic activity, and rapid forest conversion on private lands to produce commodities. A third path for private lands promoting biodiversity-based value chains could better incentivize preservation over conversion.

From desertification to restoration in the Brazilian semiarid region: Unveiling the potential of land restoration on soil microbial properties

Land desertification poses a significant challenge in the Brazilian semiarid region, encompassing a substantial portion of the country. Within this region, the detrimental effects of human activities, particularly unsuitable anthropic actions, have resulted in diminished vegetation cover and an accelerated rate of soil erosion. Notably, practices such as overgrazing and the conversion of native forests into pasturelands have played a pivotal role in exacerbating the process of land desertification. Ultimately, land desertification results in significant losses of soil organic matter and microbial diversity. To address this pressing issue and contribute to the existing literature, various land restoration practices, such as grazing exclusion, cover crops, and terracing, have been implemented in the Brazilian semiarid. These practices have shown promising results in terms of enhancing soil fertility and restoring microbial properties. Nonetheless, their effectiveness in improving soil microbial properties in the Brazilian semiarid region remains a subject of ongoing study. Recent advances in molecular techniques have improved our understanding of microbial communities in lands undergoing desertification and restoration. In this review, we focus on assessing the effectiveness of these restoration practices in revitalizing soil microbial properties, with a particular emphasis on the soil microbiome and its functions. Through a critical assessment of the impact of these practices on soil microbial properties, our research aims to provide valuable insights that can help mitigate the adverse effects of desertification and promote sustainable development in this ecologically sensitive region.