Slash-and-burn Research Articles

Sustainable Management of Land, Water and Crop in Hills of North East India

Hill agriculture in Northeast India has tremendous potential to grow and contribute towards improving productivity, enhancing food and nutrition security, reducing rural poverty and accelerating the overall economic condition of the region due to its rich land, abundant water resources and favorable climate. The North-eastern region lying between 21.5oN - 29.5oN latitudes and 85.5oE - 97.3oE longitudes comprises eight states - Assam, Arunachal Pradesh, Meghalaya, Manipur, Mizoram, Nagaland, Tripura and Sikkim. The growth potential of hill farming has remained under-exploited due to various reasons like lack of system-specific production technologies, poor infrastructure (transport, markets, processing) and underdeveloped institutions (credit, extension, information, insurance), inaccessible habitations, diverse socio-cultural and fragmented land holdings. In hilly areas, jhum cultivation provides a basis for subsistence farming, maintenance of cultural values and social stability at low population density. But in the present context, this system cannot sustain increased demographic pressure. Moreover, shifting cultivation also causes problems of land degradation, accelerated deforestation, out of control forest fires ultimately affecting climate change. Therefore, adoption of various agro techniques as an alternative to jhuming may prove to be a boon for the overall growth of the region. Cultivation of plantation crops and orchards established on hill slopes will prevent soil erosion. Watershed development also plays an important role in sustaining the natural resource base and improving the productive potential of hill states. The hill states have the potential for production of vegetables in off-season that has greater demand in neighboring plains when there is scarcity of supply as this region is bestowed with the most congenial climatic conditions for the production of under-exploited agricultural and horticultural crops that provides many fold employment opportunities in agro-based industries, packaging, storage, preservation, canning and transportation.

Unraveling the Effects of Shifting (Jhum) Cultivation on Physicochemical and Hydraulic Properties of Soil and Water Resources

Unraveling the Effects of Shifting (Jhum) Cultivation on Physicochemical and Hydraulic Properties of Soil and Water Resources

Assessing the Impacts of Dam Construction on the Livelihoods of Swidden Farmers in Pinlaung, Southern Shan State, Myanmar

Assessing the Impacts of Dam Construction on the Livelihoods of Swidden Farmers in Pinlaung, Southern Shan State, Myanmar

Upland Rice: A Water-Efficient Rice Production System in India

The rainfed upland ecosystem, although often overlooked, plays a crucial role in sustaining India's impoverished population with its limited resources. This ecosystem spans across most states in the country, covering approximately 7 million hectares, with Eastern India having the highest coverage (>90%). In the typical upland ecosystem, rice is cultivated using direct seeding, employing minimal inputs such as fertilizers, insecticides, fungicides and herbicides. Upland rice farming is widely recognized for its crucial role in sustaining subsistence agriculture, catering to the nutritional needs of rainfed farming communities during the period of scarcity, particularly towards the end of September. Among all rice ecosystems, the upland environment stands out as the most diverse. Upland rice is cultivated through various methods, including permanent cultivation, block rotations, slash-and-burn (Jhum cultivation) and is established through broadcasting, seeding behind plough, or drilling seeds in small holes. It is grown both as a single crop and in combination with other cereals, oilseeds, or pulses. In specific regions like eastern Uttar Pradesh and West Bengal, short-duration upland rice is grown under transplanted conditions. The harvest from upland rice not only serves as a crucial food source for impoverished farmers but also fulfills the feed requirements for cattle during times of scarcity. The majority of upland rice cultivation is concentrated in the Eastern Plateau and Hills Region, emphasizing subsistence farming. Addressing such challenges is crucial for maximizing the potential of upland rice cultivation and its role in sustaining rainfed agriculture in India.

Characteristics and origins of fine particulate amines at a coastal mountain site in northern China in spring

Low-molecular-weight amines are the most abundant amine compounds in the atmosphere and they affect new particle formation, aerosol properties, climate change and human health. To understand the chemical composition, diurnal variation, influences of terrestrial and marine emissions, and potential sources of fine particulate amines in the coastal area in northern China, field sampling and measurements was conducted at coastal Mt. Lao in the spring of 2021. The total concentration of amines in PM2.5 was around 60 ng m−3 on average. Dimethylamine was the most abundant compound with mean fraction of 27.2% in the quantified 16 amines, followed by diethylamine (19.6%) and ethanolamine (12.6%). Elevated concentrations of amines usually appeared with high levels of CO, SO2, NOx, and/or moderately high humidity. Amines exhibited higher concentrations during the daytime than nighttime at the mountain site, due to more intense anthropogenic activities at daytime. The concentration peak in the late afternoon is ascribed to relatively strong anthropogenic emissions and enhanced gas-to-particle partitioning. Furthermore, comparison between terrestrial- and marine-airmass dominated samples shows that most amines primarily came from terrestrial activities, while TMA was mainly from marine sources. Source apportionment with the positive matrix factorization model identified seven major sources including agricultural emissions, industrial production, biomass burning, coal combustion, marine emissions, traffic emissions and crustal dusts. Notably, high contributions from agricultural source and biomass burning were observed at this coastal mountain site, indicating differential compositions and origins of particulate amines in different seasons and locations.

Quantifying effects of long-range transport of NO2 over Delhi using back trajectories and satellite data

Abstract. Exposure to air pollution is a leading public health risk factor in India, especially over densely populated Delhi and the surrounding Indo-Gangetic Plain. During the post-monsoon seasons, the prevailing north-westerly winds are known to influence aerosol pollution events in Delhi by advecting pollutants from agricultural fires as well as from local sources. Here we investigate the year-round impact of meteorology on gaseous nitrogen oxides (NOx=NO+NO2). We use bottom-up NOx emission inventories (anthropogenic and fire) and high-resolution satellite measurement based tropospheric column NO2 (TCNO2) data, from S5P aboard TROPOMI, alongside a back-trajectory model (ROTRAJ) to investigate the balance of local and external sources influencing air pollution changes in Delhi, with a focus on different emissions sectors. Our analysis shows that accumulated emissions (i.e. integrated along the trajectory path, allowing for chemical loss) are highest under westerly, north-westerly and northerly flow during pre-monsoon (February–May) and post-monsoon (October–February) seasons. According to this analysis, during the pre-monsoon season, the highest accumulated satellite TCNO2 trajectories come from the east and north-west of Delhi. TCNO2 is elevated within Delhi and the Indo-Gangetic Plain (IGP) to the east of city. The accumulated NOx emission trajectories indicate that the transport and industry sectors together account for more than 80 % of the total accumulated emissions, which are dominated by local sources (>70 %) under easterly winds and north-westerly winds. The high accumulated emissions estimated during the pre-monsoon season under north-westerly wind directions are likely to be driven by high NOx emissions locally and in nearby regions (since NOx lifetime is reduced and the boundary layer is relatively deeper in this season). During the post-monsoon season the highest accumulated satellite TCNO2 trajectories are advected from Punjab and Haryana, where satellite TCNO2 is elevated, indicating the potential for the long-range transport of agricultural burning emissions to Delhi. However, accumulated NOx emissions indicate local (70 %) emissions from the transport sector are the largest contributor to the total accumulated emissions. High local emissions, coupled with a relatively long NOx atmospheric lifetime and shallow boundary layer, aid the build-up of emissions locally and along the trajectory path. This indicates the possibility that fire emissions datasets may not capture emissions from agricultural waste burning in the north-west sufficiently to accurately quantify their influence on Delhi air quality (AQ). Analysis of daily ground-based NO2 observations indicates that high-pollution episodes (>90th percentile) occur predominantly in the post-monsoon season, and more than 75 % of high-pollution events are primarily caused by local sources. But there is also a considerable influence from non-local (30 %) emissions from the transport sector during the post-monsoon season. Overall, we find that in the post-monsoon season, there is substantial accumulation of high local NOx emissions from the transport sector (70 % of total emissions, 70 % local), alongside the import of NOx pollution into Delhi (30 % non-local). This work indicates that both high local NOx emissions from the transport sector and the advection of highly polluted air originating from outside Delhi are of concern for the population. As a result, air quality mitigation strategies need to be adopted not only in Delhi but in the surrounding regions to successfully control this issue. In addition, our analysis suggests that the largest benefits to Delhi NOx air quality would be seen with targeted reductions in emissions from the transport and agricultural waste burning sectors, particularly during the post-monsoon season.

Leveraging limited data from wildlife monitoring in a conflict affected region in Venezuela

Efficient monitoring of biodiversity-rich areas in conflict-affected areas with poor rule of law requires a combination of different analytical approaches to account for data biases and incompleteness. In the upland Amazon region of Venezuela, in Canaima National Park, we initiated biodiversity monitoring in 2015, but it was interrupted by the establishment of a large-scale mining development plan in 2016, compromising the temporal and geographical extent of monitoring and the security of researchers. We used a resource selection function model framework that considers imperfect detectability and supplemented detections from camera trap surveys with opportunistic off-camera records (including animal tracks and direct sighting) to (1) gain insight into the value of additional occurrence records to accurately predict wildlife resource use in the perturbated area (deforestation, fire, swidden agriculture, and human settlements vicinity), (2) when faced with security and budget constraints. Our approach maximized the use of available data and accounted for biases and data gaps. Adding data from poorly sampled areas had mixed results on estimates of resource use for restricted species, but improved predictions for widespread species. If budget or resources are limited, we recommend focusing on one location with both on-camera and off-camera records over two with cameras. Combining camera trap records with other field observations (28 mammals and 16 birds) allowed us to understand responses of 17 species to deforestation, 15 to fire, and 13 to swidden agriculture. Our study encourages the use of combinations of methods to support conservation in high-biodiversity sites, where access is restricted, researchers are vulnerable, and unequal sampling efforts exist.

Estimation of hourly one square kilometer fine particulate matter concentration over Thailand using aerosol optical depth

In the recent years, concentration of fine particulate matter that are 2.5 microns or less in diameter (PM2.5) in Thailand has consistently exceeded the national ambient air quality standard. Currently, the measurement of PM2.5 concentration relies on air quality monitoring stations operated by the Pollution Control Department of Thailand (PCD). However, these stations are insufficient, particularly in rural areas, where agricultural open burning are major sources of pollution after harvesting period. This study aims to enhance the monitoring of PM2.5 concentration by leveraging cost-effective technologies. We propose the integration of satellite data, specifically Aerosol Optical Depth (AOD) from Multi-Angle Atmospheric Correction (MAIAC) product and Himawari-8 satellites, with the Weather Research and Forecasting Model (WRF) data, to provide supplementary data to the ground-based monitoring. Hourly 5 × 5 km2 AOD data from Himawari-8 were downscaled to a high-resolution of 1 × 1 km2, leveraging the AOD distribution pattern of the concurrent MAIAC product using eXtreme Gradient Boosting (XGBoost) model. Notably, during Thailand’s rainy season (May to August), the study observed a relative reduction in the training model’s R-square value. This phenomenon is attributed to temporal discrepancies between Himawari-8 and the MAIAC products during this period. The predictive models of PM2.5 concentrations with the identification of pertinent variables through Pearson’s correlation analysis and recursive feature elimination, driven by the robust XGBoost model. Subsequently, the downscaled AOD, wind speed, temperature, and pressure were identified as predictors for the estimation of hourly PM2.5 concentration. This comprehensive approach enabled the projection of PM2.5 levels across Thailand, encompassing over 600,000 grids at 1 × 1 km2 resolution. The developed models, thus, offer a valuable tool for robust and high-resolution PM2.5 concentration estimation, presenting significant implications for air quality monitoring and management in Thailand.

Producing, Characterizing and Quantifying Biochar in the Woods Using Portable Flame Cap Kilns.

One of the biggest challenges in utilizing non-commercial forest biomass is its widely distributed nature. The best solution to the biomass problem, to avoid expensive and carbon-intensive processing (chipping) and transportation costs, is to process it onsite. However, conventional burn piles have destructive impacts on forest soil and provide no benefits other than fuel reduction. Converting forest slash to biochar onsite has many ecological advantages over the current practice of slash disposal by incineration in burn piles, including reduced soil heating and particulate emissions, along with multiple benefits of the biochar to forest soil health and water holding capacity when left in place. Making biochar onsite in the woods is a way to return a pyrogenic carbon component to forest soils that has been missing due to the recent history of fire suppression. Biochar is also a leading method of carbon removal and sequestration for climate change mitigation. In this study, we document a method for making biochar using a portable biochar kiln. This low-cost method utilizes hand crews equipped with water for quenching kilns before the biochar burns to ash. Simple techniques for quantifying and characterizing the biochar produced are incorporated into the method for the purpose of measuring impact and qualifying for carbon removal certificates to help pay for the cost of the work. We describe the CM002 Component Methodology that provides standardized procedures for the quantification of GHG benefits during three stages of the process: waste biomass sourcing, biochar production, and biochar soil application. The CM002 Methodology is based on international best practices, including the most recent VCS methodology VM0044 Standards and EBC C-Sink Artisan Standards. Reliable quantification methods utilizing appropriate safety factors are the first essential step toward eligibility for carbon removal finance.

Beyond the basics: a perspective on barriers and opportunities for scaling up biochar production from forest slash

AbstractBiochar production from woody biomass generated during forest management (slash) offers significant benefits for soil health and carbon emissions, yet its adoption remains limited in the western United States (U.S.). To address this challenge, the U.S. Department of Agriculture (U.S.D.A.) Forest Service Rocky Mountain Research Station organized two workshops focused on forest management-centric biochar production. These workshops convened a diverse group of stakeholders, including investors, land management practitioners, industry professionals, and research scientists, each with unique roles in slash-based biochar production. This article presents a synthesis of the insights and perspectives gathered from these workshops, aiming to identify barriers and propose viable pathways for overcoming them. The barriers encompass governance issues such as policy and permitting, economic challenges related to costs, funding, and market stability, technological hurdles concerning methods and equipment, and a need for further research and improved science dissemination. In response to these challenges, workshop attendees collaboratively outlined specific strategies to reduce these barriers. These strategies emphasize the expansion of operational initiatives, the development of proactive policies, the stabilization of biochar markets, and the generation of additional case studies showcasing the effects of biochar amendments across various soils and environments. Collectively, the insights gleaned from this workshop series provide a comprehensive roadmap outlining both the struggles and the necessary actions and investments required to enhance the scale of slash-based biochar production and application in the western U.S. Graphical Abstract

Climate Change, Landscape Fires, and Human Health: A Global Perspective.

Landscape fires are an integral component of the Earth system and a feature of prehistoric, subsistence, and industrial economies. Specific spatiotemporal patterns of landscape fire occur in different locations around the world, shaped by the interactions between environmental and human drivers of fire activity. Seven distinct types of landscape fire emerge from these interactions: remote area fires, wildfire disasters, savanna fires, Indigenous burning, prescribed burning, agricultural burning, and deforestation fires. All can have substantial impacts on human health and well-being directly and indirectly through (a) exposure to heat flux (e.g., injuries and destructive impacts), (b) emissions (e.g., smoke-related health impacts), and (c) altered ecosystem functioning (e.g., biodiversity, amenity, water quality, and climate impacts). Minimizing the adverse effects of landscape fires on population health requires understanding how human and environmental influences on fire impacts can be modified through interventions targeted at individual, community, and regional levels.

New distribution records of the endemic pitcher plant, Nepenthes khasiana Hook. f. and identification of threats in Meghalaya, India

Aim: The present study entails new distribution records along with the identification of threats to the pitcher plant, Nepenthes khasiana Hook. f. in Meghalaya, India. Methodology: A trail survey was employed to find the distribution of pitcher plants in different locations of the Garo, Khasi, and Jaintia hills of Meghalaya between 2018 and 2022. Results: The present study reported some new distribution records in the Garo, Jaintia, and Khasi Hills of Meghalaya mostly in private lands which are scatteredly distributed. They are adversely threatened due to large-scale jhum cultivation, mining, traffic, road construction, human pressure, and tourism as depicted in the present study. Besides, the pitcher plants have been wiped out from many areas of Meghalaya which was earlier reported. Interpretation: The present work documented the distribution of pitcher plants in some new areas of the Garo, Khasi, and Jaintia Hills of Meghalaya. The population of the pitcher plant is sharply declining in Meghalaya due to various threat factors. Hence, the conservation of pitcher plant need urgent attention. Therefore, an action plan is required to safeguard the pitcher plant in these habitats. Besides public awareness, stakeholder participation is the paramount need of the hour to protect and preserve the plants. Further, new areas also need to be explored for the distribution of pitcher plants in other areas of the state including intensive studies in Garo, Khasi and Jaintia Hills. Key words: Carnivorous plants, Endemic, Meghalaya, Nepenthes khasiana, Pitcher plant

Modeling study of PM2.5 pollution episode of early spring 2019 in Hokkaido, Japan caused by biomass burning in Northeast China

Biomass burning (BB), in particular agricultural waste burning (Agri-BB), occurs at random locations, scales, and times. These factors make it challenging to detect Agri-BB accurately through satellite observations. Thus, the BB emission inventories using satellite observation data have uncertainties for their emission estimation approach and cause poor model performance for air pollutants including PM2.5. We utilized the two BB emission inventories, GFEDv4.1s and FINNv2.5 with the CMAQ model to simulate the PM2.5 heavy pollution episode in Hokkaido 2019. To estimate Agri-BB contributions, we conducted three simulation cases for each BB emission inventory: with and without Agri-BB emission, and the boosted Agri-BB emission cases. The baseline simulation failed to capture the temporal and spatial variation patterns of PM2.5. Meanwhile, the boosted Agri-BB case could show favorable performance for PM2.5 concentrations. These results indicated that the two BB emission inventories underestimated Agri-BB emissions. In the two boosted Agri-BB cases, the PM2.5 contributions from Agri-BB accounted for more than 50% during the episode. Moreover, high PM2.5 emissions were found in Northeast China and its surrounding regions similar to the two boosted Agri-BB cases. Consequently, the results revealed that Agri-BB emissions during the episode were significantly derived from the agricultural areas in Northeast China.

Agricultural production and air pollution: An investigation on crop straw fires.

In numerous developing nations, the pervasive practice of crop residue incineration is a principal contributor to atmospheric contamination in agricultural operations. This study examines the repercussions of such biomass combustion on air quality during the autumnal harvest season, utilizing data acquired from satellite-based remote sensing of fire events and air pollution measurements. Employing wind direction information alongside difference-in-difference and fixed-effects methodologies, this investigation rectifies estimation inaccuracies stemming from the non-random distribution of combustion occurrences. The empirical findings reveal that agricultural residue burning precipitates an elevation in average PM2.5 and PM10 concentrations by approximately 27 and 22 μg/m3 during the autumnal incineration period, respectively. Furthermore, air pollution attributed to residue burning in prominent grain-producing regions exceeds the national average by approximately 40%. By integrating economic paradigms into agri-environmental inquiries, this study offers novel insights and substantiation of the environmental expenditures engendered by crop residue burning, juxtaposed with extant meteorological and ecological research findings.

Effect of Shifting Cultivation on Soil health and Microbial Diversity in Junnar Taluka of Pune District

Background: Swidden cultivation, slash and burn cultivation, and bush-fallow agriculture are other names for shifting cultivation. Around the world, its name is different. Crop type and farming methods have an impact on the physico-chemical properties of the soil. Soil health is also influenced by the quantity and biomass of microorganisms present.
 Aims: The goal of the current study was to determine how soil bacterial communities and soil quality in Pune district's western ghat region were affected by shifting farming.
 Study Design: 18 soil samples from 4 villages of the Junnar tehsil were collected after harvesting the cultivated crop.
 Place and Duration of Study: The sample was collected within the 2 to 4 acres of the shifting cultivation plots identified in the villages in the western ghat region of Pune district.
 Methodology: The soil samples were collected after harvesting every crop and from the fallow land. Analysis of Physico–Chemical properties of soil samples was performed. Bacteria were isolated and identified from the soil samples. Statistical analysis was done to interpret the obtained results.
 Results: The fallow land and crop (Varai, Khursani, Sawa, Nachani, and Hulga) harvested soils were among the soil samples. Different numbers of ten distinct bacterial genuses were isolated from each soil. When compared to fallow soil, the Total Viable Count (TVC) of the crop harvest soil was shown to have significantly dropped. It was also discovered that certain soil characteristics improved throughout the fallow period.
 Conclusion: The results pointing out the importance of the length of the fallowing on the soil health and thus on the crop yield.

Assessment of Carbon Stock in Response to Varied Land Use Systems and Soil Depths in Chandel District, Manipur, India

To understand the effects of land use system and its cropping techniques, the study on carbon stock and soil nutrients in response to varied land use systems and soil depths in Chandel district was carried out during 2020 from five different locations in the Chandel district that include a variety of land use systems such as Forest area, Jhum cultivation after 15 years, Jhum cultivation after 10 years, Jhum cultivation after 10 years from different sub division of the district, Jhum cultivation after 5 years, Intermittent Jhum area, Oak forest area, Teak forest area, Pine forest area, Agri-horti jhum cropping system area and Maize based cropping system area. The study revealed that Forest soils shows significantly higher Organic carbon content of 2.73 % in 0-15 cm and 2.04% in 30-45 cm soil depth respectively than the other land use system of Chandel district. Available N was also found to be significantly higher in forest soils i.e. 533.49 kg/ha in 0-15 cm soil depth and 475.14 kg/ha in 30-45 cm soil depth as compared to other land use systems. Similarly, available P2O5 of 10.92 kg/ha and 9.97 kg/ha in 0-15 cm and 30-45 cm soil depth respectively and K2O of 278.08 kg/ha in 0-15 cm and 266.11 kg/ha in 30-45 cm were also recorded to be significantly higher in forest soil which was followed by the Jhum cultivation after 15 years in Chandel district. Next to forest area soils, Jhum cultivation after 15 years shows higher organic carbon content and other soil nutrients as compare to other land use systems due to the longer waiting period of cultivation. These results indicated that the land under more vegetation and less disturbed areas have higher soil nutrient and organic carbon as compared to other land use system. Thus it may be concluded that, variations in soil fertility parameters need immediate improvement in soil health of Jhum lands and other land use systems.

Emission characteristics of carbonyl compounds from open burning of typical subtropical biomass in South China

Open biomass burning (OBB) is one of the largest primary emission sources for atmospheric carbonyl compounds, key precursors for ozone and secondary organic aerosol pollution. To clarify the carbonyl emissions, the comprehensive characteristics of C1–C10 carbonyl compounds from open burning of seven typical subtropical biomass in China were investigated in this study, which included subtropical plants and agricultural residues. Total 27 carbonyl compounds were detected. The total EFs were 2824 mg kg−1 with 95% confidence interval (CI) [2418, 3322] for burning subtropical plants and 4080 mg kg−1 with 95% CI [3446, 4724] for burning agriculture residues, respectively. The EFs were 2–3 orders of magnitude larger than previous values in China. Aliphatic aldehydes were the largest group of carbonyl groups, with acetaldehyde, as the most abundant carbonyl species (about 30% contribution). Formaldehyde, acetone, acrolein, glyoxal, methylglyoxal, butanone, isovaleraldehyde, and m-tolualdehyde were also found to be abundant and varying with the types of biomass burnt. Formaldehyde emission ratios to acetonitrile and CO were lower than those in previous studies both for burning plants and agricultural residues. There were significant variabilities in the emission ratios and factors among different types of OBBs. Strong positive correlations were found between carbonyl emissions and CO emissions and water content in biomass; furthermore, total carbonyl concentrations measured in the flaming stage were higher than those in the smoldering one. This study provides important fundamental measurement data on carbonyl emissions from burning typical subtropical plants and agricultural residues, which will help improve the quality of emission inventories and better understand the potential impacts of OBB on regional air quality in southern China.

Development of a source-specific biomass burning emissions inventory for Washington, Oregon, and California

While wildfires are the dominant source of biomass burning emissions across the U.S., prescribed and agricultural burns also contribute to emissions and ambient air quality. Understanding the differential impacts that these different sources of biomass burning have on air quality and public health is important in the development of effective exposure reduction strategies. We leverage the high-resolution Fire INventory from NCAR (FINN) to develop a source-specific biomass burning emission inventory that distinguishes between wildfire, prescribed burn, and agricultural burn sources across Washington, Oregon, and California. We describe the methodology for reclassifying FINN using multiple national and state-level fire and fuel treatment inventories and present the results of the emissions reclassification process for these three states from 2012 to 2020. We matched 72%, 78% and 81% of FINN emissions event locations to fire locations from the fire type input datasets in Washington, Oregon, and California, respectively. When compared to county-level fire type-specific PM2.5 emissions estimates from the 2014, 2017, and 2020 EPA National Emissions Inventory, we found greater agreement among wildfire-specific estimates across years and states (R2 range: 0.59–0.98), relative to prescribed (R2 range: 0.12–0.73) and agricultural burns (R2 range: 0.43–0.95). This fire type-specific biomass burning emissions inventory can be used in air pollution transport models to better understand the impacts of each of these sources on air quality across the region along with downstream public health impacts.

Foliar non-structural carbohydrates and resprouting ability of woody species in a tropical dry forest

Diverse disturbances contribute to biomass loss in tropical dry forests (TDF), of which slash-and-burn agriculture (SBA) may be the most severe; it is practiced by large populations of residents. Plant species capable of resprouting in response to such disturbances often possess above-ground structures that survive and mobilize resources for resprouting, in addition to below-ground structures. In Brazilian TDF, woody species regenerating from stem pieces that persist after SBA events are common. In this study, we evaluated the foliar concentrations of non-structural carbohydrates (NSC) and mineral nutrients during the first six months after an SBA event in all species that resprouted within the experimental area. Almost all the species resprouted exclusively from the stems. The measured nutrient concentrations did not change drastically after an SBA event. Two patterns were observed with respect to NSC concentrations among the species. Half of the studied species exhibited high concentrations of NSC before the SBA event, which gradually decreased three and six months after the disturbance. In contrast, the remaining species maintained consistent NSC concentrations throughout the study period. The cost of building new leaf tissue was similar for all species before the SBA event. However, after disturbance, the species invested different amounts of carbon into the new leaves. Those species that decreased NSC leaf concentration after SBA showed the highest regrowth intensity through the number of new tillers. Our results suggest that the intense translocation of NSC from the leaves before SBA may support the increased activity of the buds present in the remaining stem piece.

Agrobiodiversity, Social Institutions, and Indigenous Farming Practices: A Case Study of the Rukai in Wutai, Taiwan

Agrobiodiversity plays a crucial role in maintaining sustainable agricultural systems and supporting local livelihoods, but its integration into indigenous social institutions and cultures remains under-researched. We used a qualitative approach entailing in-depth interviews and participant observation to conduct research among the Rukai indigenous farmers in Taiwan focusing on: (1) how Rukai farmers practice agrobiodiversity, and (2) how these agricultural practices integrated into social institutions and cultural norms. Our findings reveal that food security and risk minimization are the prime considerations to preserve agrobiodiversity. Rukai farmers practice swidden cultivation utilizing five mixed cropping systems in seven different ecosystems that vary by elevation, length of exposure to sunlight, and temperature, intercropping, and regular fallows to maintain soil fertility. Importantly, Rukai agricultural practices are integrated into four social institutions that regulate the distribution and management of land and resources, the timing and nature of agricultural activities, and social recognition and status to ensure maximum production throughout the year and reducing risks posed by climate change.