Secondary Forest Areas Research Articles

Impact of urban disturbance on soil insect communities in a Brazilian Atlantic Forest biological station

Urbanization constitutes a major threat to biodiversity. Understanding its effects on insect communities is relevant because they are key elements of trophic interactions, and indicators and targets of conservation. Herein, we investigated the influence of meteorological and habitat factors on the soil entomofauna in three areas with distinct levels of urbanization at the Parque Estadual da Pedra Branca, Brazil. We investigated whether community structure differs among areas with different levels of urbanization, and how changes in the environment affect soil insect community composition and distribution. We systematically monitored communities for 12 months in three areas along a gradient of anthropogenic disturbance, representing preserved secondary forest, disturbed forest and peridomicile areas. The results revealed that the degree of urbanization affects insect communities, with a strong effect of habitat factors, such as canopy cover, presence of flooded areas, quantity of fallen trunks and mean temperature. Insect abundance did not show significant differences among areas, while biomass was higher in disturbed forest than in preserved forest and peridomicile areas. Additionally, insect richness and diversity were higher in preserved and disturbed forests than in peridomicile areas, with no significant difference between preserved and disturbed forests. Our results can be used to enhance the understanding of the effects of urbanization on taxonomically and functionally diverse groups of insects, and to advise residents and urban planners about the consequences of urbanization on biodiversity and ecosystem services in urban-sylvatic interface areas.

Beyond the surface: microbiological and biochemical attributes as indicators of soil quality in Atlantic Forest ecosystem

The objective of this study was to determine the biochemical and microbiological attributes in areas with different vegetation covers (mature forest, secondary forest, and sugar cane monoculture) and seasonal changes, and to compare the sensitivity of these attributes types (mycorrhizal, enzymatic, and carbon attributes) in response to changes in vegetation cover and season. Soil samplings were conducted over two years (one per semester, during the dry and wet periods of 2007 and 2008) in three types of areas: (I) mature forest; (II) secondary forest; and (III) sugar cane crop. The enzymatic activity of fluorescein diacetate, dehydrogenase, saccharase, basal carbon respiration, the carbon content of microbial biomass, the microbial coefficient, total and easily extracted glomalin soil-related proteins, mycorrhizal colonization, the number of glomerospores, total organic carbon, fulvic and humic acid content, and the fulvic/humic acid ratio were analyzed. In general, mycorrhizal parameters were more sensitive in distinguishing areas with different types of vegetation cover. Additionally, carbon stocks in areas of mature and secondary forest were higher compared to areas cultivated with sugar cane. The study reveals that mycorrhizal properties, such as root colonization and GRSP fractions, are more sensitive indicators of soil health than soil C attributes, providing a cost-effective alternative for evaluating soil health in the Atlantic Forest. The confirmed hypothesis supports the effectiveness of microbiological activity and C dynamics in discerning significant changes between sugar cane cultivation and forested areas. The study underscores the vital role of conserving forested areas, serving as crucial carbon reservoirs, and emphasizes the potential for enhanced sustainability through conservation practices and rapid soil function recovery in secondary forests within the Atlantic Forest.

Pasture Recovery Period Affects Humic Substances and Oxidations of Organic Matter in Eastern Amazon

Land management practices that overlook soil limitations and potential have led to varying degrees of degradation. This study evaluates the carbon content in chemical and oxidisable soil fractions across different pasture recovery periods, comparing them to secondary forests. The management practices assessed include the following: secondary forest (SF), perennial pasture (PP), perennial pasture recovered five years ago (P5), and perennial pasture recovered eight years ago (P8), all on Plinthosols. We analysed carbon levels in oxidisable fractions and humic substances at depths of 0–0.10 m, 0.10–0.20 m, 0.20–0.30 m, and 0.30–0.40 m. The SF and P8 areas showed the highest organic matter content within the humic fractions, compared to the PP and P5 areas. Additionally, the P8 area demonstrated an increase in the labile and moderately recalcitrant fractions of organic matter, standing out among the different fractions evaluated. The multivariate principal component analysis indicated that P8 has the greatest impact on soil quality, followed by FS, P5, and PP. The pasture recovery over the past eight years has significantly improved soil carbon accumulation, highlighting the benefits of land restoration.

Soil fauna changing in after‐pine harvesting's areas along a temporal gradient of Atlantic Forest regeneration

AbstractMonoculture of pine alters the soil fauna community structure, but forest farms, mixed with natural areas, are restoring the original vegetation to protect, the diversity and ecosystem functions. In restoration initiatives it is necessary to consider the soil fauna. Thus, the aim of this study was to investigate how the process of restoration of the soil community occurs over time in areas after pine harvesting. Areas in natural regeneration with 4 and 10 years, pine plantations adjacent to these areas (representing previous use), and areas of natural forest (reference) were evaluated, it was evaluated three areas per treatment, with six sampling points spaced 30 m apart, totalling 18 sampling points for each treatment (n = 18). Soil mesofauna and macrofauna were collected through soil monoliths and pitfall traps. The comparison of the statistical analysis was to check for changes in the soil fauna over time (4 and 10 years) compared with that observed in secondary forest areas. The study showed that, along the natural regeneration time (4 and 10 years), it was observed increments in the diversity and evenness of the soil community and a reduction in the dominance of groups like Formicidae and increases in the community structure complexity with the resurgence of micropredators/regulators (Collembola and Acari), litter transformers (Oligochaeta, Diplopoda, Blattodea, Coleoptera (Larva), Diptera (Larva) and Coleoptera) and predators (Pseudoscorpiones, Opiliones, Symphyla and Coleoptera) after 10 years of natural regeneration, the areas have already recovered groups with important ecosystem functions, but are not yet at the level of abundance, functional diversity and community structure of native forest areas. The 4‐ and 10‐year regeneration areas present major number of soil fauna groups of native forest (20 groups in regeneration areas and 17 in the native forest areas). Even so, the forest showed a major complexity of soil fauna community structure, evidenced by the diversity. This study contributes to the understanding of natural regeneration for soil fauna along a temporal gradient and these findings can guide the conservation of regional soil fauna diversity.

Identifying the impact of climate extremes on radial growth in young tropical trees: A comparison of inventory and tree-ring based estimates

The loss of tropical forest resilience has been linked to increased climate variability and associated droughts, but the response of tropical trees to climate extremes remains poorly understood. This limits our ability to design effective forest adaptation strategies in the tropics. Here we analyse the potential of using young trees to analyse climate variability and extremes, which opens new avenues given the increasing area of secondary forests and tree plantations. We used annual tree diameter measurements and stem discs from 139 16-year-old trees belonging to five native species planted in the Sardinilla tree diversity experiment in Panama and compared three methods to determine annual radial growth. Employing inventory measurements, visual stem disc analysis, and wood density measurements, series of radial growth were calculated to compare relative growth during wet and dry extreme events, and to compute continuous climate-growth correlations. Our results show that annual radial growth data derived from wood density profiles are best suited for climate-growth relationships, as they could capture a common growth signal within the high intraspecific variability of young trees to seasonal climatic variables. Annual radial growth data derived visually and from inventories are still useful for quantifying growth responses during extreme drought. The highest similarity among methods to determine annual radial growth, combined with the strongest climate-growth relationships, were found for Cedrela odorata, a species that shows a pronounced decrease in water use and cambial dormancy during the dry season. Stem discs from young trees planted in tropical forest plantations may thus offer a suitable source for dendroecological analyses.

Understanding Japan's Land-use Dynamics between 1987 and 2050 using Land Accounting and Scenario Analysis

Amidst global concerns about land use change and its far-reaching impact on biodiversity and human well-being, there is a growing need to understand how land use stock and flow changes over time through land use accounting. While existing studies on land accounting have focused on historical land changes, little attention has been paid to future transitions. This study assessed historical patterns and projected future shifts in land use dynamics from 1987 to 2050 across Japan by combining high-resolution land use and land cover datasets, land change simulations, and land accounting. In the analyses, particular attention was paid to the historical and future trends of farmland abandonment by leveraging data at 100-m resolution built on national vegetation surveys. High-resolution analysis of farmland abandonment issue with national scale in Japan is a novelty. From 1987 to 1998, the land stock analysis results showed a pronounced marked increase in residential land (10.4%) and grassland (16.9%); the flow analysis results showed that urban residential sprawl expansion was mainly formed by secondary (32.6%) and plantation (21.1%) forest areas, coinciding with increasing population and economic growth. Projections from 2010 to 2050 indicate a marked increase in abandoned farmland (67.2% per decade), a trend influenced by rapid population decline and presumably agricultural policies, especially significant in regions such as Hokkaido and Kyushu. The findings of this study are crucial for shaping policy and decision-making, underlining the need for sustainable land management strategies that effectively balance urban growth, agricultural productivity, and environmental preservation in Japan.

New Species, Host Record, and Male Discovery for Three Messatoporus Cushman (Hymenoptera, Ichneumonidae, Cryptinae) from Brazil

Messatoporus bisignatus Aguiar & Supeleto, sp. nov. is described and illustrated. The new species was extensively reared from trap nests colonized by Auplopus subaurarius Dreisbach, 1963 (Hymenoptera, Pompilidae), in an area of secondary Atlantic Forest in southern Brazil. Two other species, M. elektor Santos, 2013 and M. opacus Santos, 2013, were also reared from the same host, but in lesser numbers. The previously unknown males of M. elektor Santos, 2013, M. opacus Santos 2013 and M. unidentatus Santos, 2013 are described and illustrated. New females and significant morphological variation are reported for these species, previously known only from a few specimens. New geographical records are reported for M. unidentatus (Brazil, two localities in ES), M. elektor and M. opacus (Brazil, two localities in RS).

Post-landslide restoration through multistrata agroforestry-based land management in the West Bogor area of Indonesia

The West Bogor area experienced a landslide disaster, causing extensive damage to secondary forest areas, plantations, and residential homes. Despite evacuations, the community persists in using the affected land for agriculture. This study aims to develop a land management model based on agroforestry for post-landslide restoration, to prevent landslide reactivation, and to provide benefits for the local community. Introducing an agroforestry system that includes deep-rooted trees and perennial crops on landslide-prone slopes can improve slope stability by enhancing soil structure and water retention, minimising erosion and landslides. The study examines unexplored aspects of landslide characteristics and zoning as a novel approach to improve mitigation strategies. We classify the post-landslides area into depletion, transition, and accumulation zones. The lithology comprises Breccia with pumice and Andesite gravels, a sandy tuff matrix, and Claystone underneath, acting as the slip surface. The northern landslide has depletion, transition, and accumulation zones ranging from 743 to 710 m above sea level (masl), 710 to 694 masl, and 694 to 676 masl. In the southern landslide, these zones range from 783 to 720 masl, 720 to 705 masl, and 705 to 676 masl. Based on the characteristics of those zones, we develop an agroforestry model in a vertical pattern with species strata, fast-growing local plants, strong and deep roots, and a relatively high evapotranspiration rate. The depletion zone is managed as a complex agroforestry system (forest type) consisting primarily of forest plants and plantation crops. The transition zone is a complex agroforestry (garden type) with plantation crops and some forest plants. The accumulation zone is a simple agroforestry system with seasonal crops. On almost flat land in an accumulation zone suitable for Oryza sativa cultivation, we apply Cocos nucifera as a protective plant. Soil fertility in all zones is improved with organic and inorganic fertilization, and it also increases the mycorrhizal population through the planting of leguminous plants. The multistrata agroforestry model, created and adapted to the specific characteristics and zoning of landslide-prone areas, is expected to significantly enhance landslide restoration and erosion mitigation and reduce the risk of future landslides. Such approaches can be extended to regions with comparable characteristics.

Determining Water Use Patterns for the Betula platyphylla in the Southern Greater Khingan Mountains and Its Adaptation to Drought

Due to global climate change, seasonal droughts have intensified and become more frequent in certain semi-arid regions, and plants often adjust their water uptake depths to adapt to shifting environmental conditions. The southern Greater Khingan Mountains have a large natural secondary forest area and act as an important ecological barrier. This study focused on examining the water use patterns of the primary plant species, Betula platyphylla, within the natural secondary forest of the southern Greater Khingan Mountains. The investigation utilized oxygen stable isotope techniques and covered a timeframe spanning from July 2019 to September 2020. The findings indicate that the adaptable water utilization strategies and rapid response to precipitation could facilitate plants fully utilizing water from all depths, thereby enabling them to better adapt to arid environments. When the rainfall was low (390.4 mm in the growing season of 2019), the developed shallow roots quickly absorbed shallow soil water (0–20 cm, with a utilization ratio of 40.4% for the entire root depth), but when the rainfall increased (501.5 mm in the growing season of 2020), Betula platyphylla gradually transitioned to extracting soil water from deeper soil layers (40–60 cm) and deepened its root system (with a utilization ratio of 39.4%), indicating its adaptability to semi-arid environments. Therefore, the flexible water use strategy of Betula platyphylla in the same habitat may give it a competitive advantage during low rainfall periods. The findings are important for the protection of natural forests and water management in the southern Greater Khingan Mountains.

Pemetaan Zonasi Daerah Rawan Kebakaran Hutan Berbasis Sistem Informasi Geografis (SIG) di Kawasan Taman Nasional Kerinci Seblat

This study aims to determine the zoning level of vulnerability and the distribution of forest fire prone areas in the TNKS SPTN Region III Painan Resort Kambang. This research uses descriptive method with quantitative approach. Data analysis techniques used are scoring and overlay. The results showed 1) The level of forest fire vulnerability there are two classes of vulnerability, low class of 173,015.62 hectares generally located in the rain forest. Medium class 115,14.76 hectares are in primary and secondary dryland forest areas, fields, dryland farms, rice fields and shrubs.2) The distribution of fire-prone areas there are a total of 31 hotspots, moderate category 24 points are in dryland farms mixed with shrubs and fields, high category 6 points are in rainforest areas and dryland farms mixed with shrubs, for low category 1 point is in the rainforest area. Based on this data, it can be concluded that most of the forests in Kambang Resort are in the medium and low vulnerability class zones.

The Diversity of Stingless Bees (Hymenoptera: Meliponini) in Belaban Resort, Bukit Baka Bukit Raya National Park

Kelulut (Hymenoptera: Meliponini) is a honey-producing bee and belongs to the eusocial bee group. Kelulut is also a pollinating insect that is widespread in the world, including Indonesia. The study of kelulut diversity can describe the composition of kelulut in an area and the condition of an ecosystem. This study aimed to obtain data and information on kelulut diversity in three different forest areas (primary forest, secondary forest, and ecosystem restoration area). The study was conducted by capturing kelulut using sugar solution bait traps and free sampling. The results obtained were analyzed using the Shannon-Wiener Diversity Index (H'), the Evenness index (E) and the Simpson Dominance Index (C). A total of 747 individuals from 12 types of kelulut were found in this study. The secondary forest gets the highest H' value (1.869), followed by the primary forest (1.672) and ecosystem restoration area (1.159). The diversity of stingless bees is higher in forested areas due to environmental factors such as temperatures within the normal range (25.5-28.9°C), the availability of trees for nesting, and the abundance of food sources from flowers.

Loss of carbon stock as an impact of anthropogenic activities in a protected mangrove forest

Abstract. Eddy S, Setiawan AA, Taufik M, Oktavia M, Utomo B, Milantara N. 2023. Loss of carbon stock as an impact of anthropogenic activities in a protected mangrove forest. Biodiversitas 24: 6493-6501. The significant anthropogenic activities within the mangrove forest, known as the Air Telang Protected Forest (ATPF) in the Banyuasin District, South Sumatra, Indonesia, have led to an alarming degradation, leaving only its primary mangrove forests, currently constituting approximately 26% of the total forest area. This study aims to analyze changes in land cover, quantify carbon reserve loss due to CO2 emissions, and assess carbon sequestration in the ATPF over two periods: 1999-2010 and 2010-2023. Remote sensing data for 1999, 2010, and 2023 were utilized from Landsat imagery, employing ENVI and ArcGIS for land cover classification. Carbon density, CO2 emissions, and carbon sequestration were analysed using the Land Use Planning for Multiple Environmental Services (LUMENS) software. The research findings reveal an increase in the primary forest area in the first period (by almost a quarter); however, more than half of this area was lost in the second period. The secondary forest area consistently decreased over the two periods, while the open area experienced significant growth. Carbon stocks in 2010 exceeded those in 1999 due to an increase in the primary forest area, but by 2023, carbon stocks decreased significantly due to extensive land clearing. The second period witnessed the largest emissions, exceeding those of the previous period by five times. Carbon sequestration in the first period surpassed that in the second period by more than three times, with the most significant sequestration resulting from the growth of secondary mangrove forests into primary mangrove forests. The study highlights the necessity of restoration and conservation of mangrove forest areas in ATPF for sustenance of its natural function as a protected forest.

Preliminary study of Dent's monkey (Cercopithecus denti) living in a forest fragment in Rwanda, highlighting dietary flexibility in guenons

AbstractCercopithecus monkeys are a species‐rich genus generally considered arboreal frugivores with widespread distribution in sub‐Saharan African forests. We studied a largely undocumented species threatened by habitat fragmentation, Cercopithecus denti, during 3 months in 2017 in a small forest fragment of Nyungwe National Park, Rwanda. C. denti's diet was composed of about 58% leaves and 18% fruits. They spent most of their time 10–20 m above ground in secondary forest and open areas. This first systematic study of C. denti shows capacity for a highly folivorous diet, supporting arguments that Cercopithecus have flexible diets, likely enabling persistence in forest fragments.

Spatiotemporal changes of forest vegetation after the implementation of a natural forest protection project and underlying driving factors: Case study of a typical natural secondary forest area in the Loess Plateau

The Natural Forest Protection Project (NFPP) in China is the first large-scale ecological restoration project aimed at protecting natural forest resources in the world. However, since its implementation in 1998, there was a lack of accurate quantitative evaluation of the ecological governance and restoration effects. This study investigated the core forest area of Ziwuling on the Loess Plateau (LP). Using the Google Earth Engine (GEE) and the Landsat remote sensing dataset, a multidimensional classification feature set comprising spectrum + vegetation index + texture + terrain was constructed by extracting multitemporal remote sensing information. With the help of land use and vegetation type data, a sample database was established, after which the random forest algorithm was used to realize the automatic classification of the five periods of the study area in 2000, 2005, 2010, 2015 and 2020. Combined with geostatistical methods such as Theil-Sen (Sen) trend analysis, Mann-Kendall (MK) trend test and geographic detectors, we realized the trend analysis of the driving factors of vegetation growth and the contribution analysis of the spatial differentiation of different vegetation types. The results showed that: (1) From 2000 to 2020, the vegetation area increased by 141.92 km2. In terms of structural composition, the vegetation was dominated by hardwood forest, followed by sagebrush, and low coverage of coniferous forest. (2) Over time, the expansion of vegetation showed a positive slowing trend, and the growth rate in 2000–2005 was significantly higher than in 2005–2020. (3) The main driving force affecting vegetation restoration is precipitation, and the temperature plays a regulating role. (4) The main driving factors affecting the spatial differentiation of vegetation were annual maximum temperature, annual average temperature, and aspect. These findings not only help us understand the intuitive contribution of the NFPP to the vegetation restoration and ecological management of the LP, but also provide an important reference for future studies using remote sensing technology in ecological restoration monitoring.

Epiphytic Host Tree Identification In Samarinda Botanical Garden

Epiphytes are one of the most diversiform plants, which its species richness peak in the tropic and subtropics. The objective of this study is to explore the different types of phorophyte. This research used the single plot method, as many as 100 plots, each measuring 10m x 10m, randomly distributed in Main Protected Zone of the Samarinda Botanical Garden. In each plot, the following data recorded the species name and individual numbers of phorophytes. The phorophyte in the old secondary forest area to the amount of 66 trees are consisting of 30 species of 29 families. The number of phorophytes is mostly in the diameter class between 21-38 cm. The Family of Dipterocarpaceae and species of Borassodendron borneensios, being the phorophyte which has got the most one in which each 8 species and 9 trees are existed in the forest.

Water infiltration rate of illegal mining sites in Bukit Soeharto Forest Park, East Kalimantan Province

Infiltration is a component of the hydrological cycle which functions as a source of groundwater, minimizing flooding and distributing water evenly throughout the rainy and dry seasons. This study aims to determine the rate of water infiltration or infiltration and permeability values in 2 (two) land conditions for ex-illegal mining sites, namely at KM 68 and KM 48, and the location of undisturbed land in KM 54 secondary forest area of the Bukit Soeharto Forest Park (BSFP). The research method used a double ring infiltrometer, then tested at the Kalimantan Bioresources Laboratory. Infiltration rate shows that secondary forest area of the KM 54 location was 275.2 mm/hour which was included in the very fast class, while in the former mining sites KM 68 and KM 48 respectively it was 244.6 mm/hour, and 145.7 mm/hour which is included in the fast class. Laboratory analysis shows that the soil permeability value in the secondary forest area of KM 54 location was 6.41 cm/hour which was included in the rather fast class, while the permeability value in the ex-mining land area of KM 68 and KM 48 respectively was 6. 26 cm/hour and 3.66 cm/hour which are included in the medium class. This is due to the physical soil properties such as soil texture, soil structure, bulk density, and soil porosity which are the factors that cause differences in infiltration rates in several land conditions.

Species-richness, abundance, and body size of stream-breeding anurans across land-use types in Sabah, Malaysia (Borneo)

Approximately 70% of Earth’s surface is impacted by human land-use. While numerous studies have demonstrated that species richness is higher in primary (undisturbed) forest than in secondary forest or agriculture sites, some studies fail to detect differences in species richness across land-use type. Recent work suggests that individual-level changes such as body size or body condition can occur more rapidly than population- or community-level processes, such as abundance and species richness, respectively. Thus, body size and condition may be more sensitive measures of environmental changes. We examined body size, body condition, abundance, and species richness of anurans in primary forest, secondary forest, and agriculture in Sabah, Malaysian Borneo, to determine whether individual-, population-, and community-level measures show similar sensitivities to land-use type. We found that observed anuran species richness and estimated population size are lower in agriculture than in primary or secondary forest, as were body size (SVL), mass, and body condition of female Meristogenys orphnocnemis. Further, anuran body condition (all species pooled) was higher in primary forest than agriculture or secondary forest, and size (SVL), mass, and body condition of male M. orphnocnemis were higher in primary forest than in agriculture or secondary forest areas. Collectively, our data demonstrate that primary forests are the best habitat for anurans in Sabah, and that individual-level processes such as size, mass, and body condition, show larger differences across land-use type than population- (abundance) or community-level processes (species richness). These data highlight the importance of primary forest for preserving anuran biodiversity in Borneo.

Spillover of avian seed dispersers between secondary forests and degraded areas in a tropical island

Seed arrival to degraded areas often represents a limiting factor to forest regeneration, but seed-dispersing birds able to move into such areas may help to overcome such constraint. As the number of degraded areas prone to regeneration is increasing in the tropics, it is important to know which bird species and associated traits make such spillover movements. We studied the interactions between frugivorous birds and eight plant species in contiguous degraded and secondary forest areas in a Brazilian land-bridge island, evaluating the potential of avian cross-habitat spillover to disperse seeds to degraded areas and thus contribute to their vegetation recovery. We recorded 21 and 17 bird species removing fruits in degraded areas and secondary forests, respectively. Avian communities dispersing seeds in both habitats are dominated by habitat generalist species. Visitation and fruit removal rates did not differ between the two habitats. Avian cross-habitat spillovers were more frequent from secondary forests to degraded areas than the reverse. A few bird species (Dacnis cayana, Elaenia flavogaster, and Turdus spp.) stood out in the spillover between habitats due to their generalist habitat occupancy and capacity for foraging in disturbed areas. We likewise identified the plants that most attracted birds (including an exotic palm, Livistona chinensis) so as to pinpoint the plant species that may occasionally be the focus of management actions to enhance the arrival of seeds to degraded areas. We conclude that the spillover dynamics reported herein shed some light on how tropical forest regeneration could benefit from native species’ spatial behaviour, offering a biological alternative to overcome practical issues, such as seed limitation in degraded environments.

Total Carbon and Nitrogen and Granulometric Fractions of Soil Organic Matter Under No-Till System and Conventional Tillage with Onion Cultivation

Objective: The objective of this work was to evaluate the total carbon (C) and nitrogen (N) contents and the granulometric fractions of soil organic matter (SOM) under different management systems with single and intercropped winter cover crops in the cultivation of onion in Ituporanga, SC. Theoretical framework: Onion cultivation typically occurs in a conventional tillage system (CTC), which favors the loss of C and N from the soil due to soil mobilization. The vegetable no-tillage system (VNTS) uses sustainable practices with continuous soil cover and restricted soil tillage, promoting improvement of edaphic attributes. Methodology: The experiment was implemented in 2009 and the collection of soil samples took place in 2019 in the layers of 0-5, 5-10 and 10-30 cm in the treatments under VNTS, being black oat (AV); rye (CE); oilseed radish (NB); rye + radish (CE+NB); black oat + oilseed radish (AV+NB) and spontaneous vegetation (VE). In addition to these treatments, two adjacent areas were used, one under CTS and the other in a secondary forest area (MATA). The content of total organic C (TOC), total N (NT), light organic matter in water (LOM), particulate organic carbon (POC), particulate nitrogen (PN), C associated with minerals (COam) and N associated with to minerals (NAM). Results and conclusions: VNTS increased TOC and NT contents with the use of grass and cruciferous intercropping to the detriment of single crops and CTS. The LOM content was higher in VNTS with the use of single grasses and stood out in relation to VNTS with consortium. There were no differences for PN between MATA, CE and CE+NB, demonstrating that VNTS is efficient in raising these levels in substitution of CTS. The CE+NB consortium increased the levels of COam and NAM in the surface layer of the soil after replacing CTS with VNTS. Research implications: In VNTS, the use of intercropping between cover crops is an efficient management in adding C and N to the soil, as the simultaneous cultivation of different species of cover crops produces straw with an intermediate C/N ratio, the roots exploit different soil extracts and nutrient cycling is more efficient. Originality/Value: The results of this study are from a long-term experiment (10 years), which demonstrates the effectiveness of VNTS in recovering and increasing C and N levels in soil previously cultivated for a long period in the CTS, in addition to to match the forest area.

Accurate dating of tropical secondary forests using wood core Δ14C in Malaysia

Following the widespread loss and degradation of old-growth forests throughout the tropics, the area of secondary forests has expanded significantly in the past few decades. Understanding the history of vegetation modification is necessary for the proper maintenance and management of tropical secondary forests. Although satellite image analysis is an effective method for evaluating such changes, observations in tropical regions are limited by dense cloud coverage, and it is difficult to estimate the timings of forest disturbances based on annual rings because the climate is aseasonal and trees do not form clear annual rings near the equator in Southeast Asia. In this study, we developed a new, highly accurate technique for dating tropical secondary forests after disturbances such as shifting cultivation and forest fire in Malaysia based on Δ14C content of trees. We established 29 plots (20 m × 20 m) in secondary forests in six areas of Malaysia, mainly in Sarawak, and used time-series satellite images to determine the most recent disturbance with temporal accuracy of <6 years. We collected wood core samples from one or two trees with the largest diameter in each plot and measured the Δ14C content of their pith to estimate tree ages. We detected a significant positive correlation between tree age estimated by Δ14C dating and the period since the latest disturbance according to the time-series satellite images. The Δ14C-based age estimates were approximately five years younger than those obtained by satellite image dating. This difference is considered to indicate the time required for land use shifts after clear cutting or forest fire, and for tree species invasion after land abandonment. Together, our results revealed that the Δ14C method may be used to date tropical secondary forests after disturbance with high accuracy, even in aseasonal tropical rainforest areas.