Impact of secondary forest fallow period on soil microbial biomass carbon and enzyme activity dynamics under shifting cultivation in North Eastern Hill region, India

Lungmuana,; Singh, Soibam Khogen; Vanthawmliana,; Saha, Saurav; Dutta, Sunil; Rambuatsaiha,; Singh, Akoijam Ratankumar; Boopathi, T.

doi:10.1016/j.catena.2017.03.017

Cited by 30 publications

(22 citation statements)

References 36 publications

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“…Fallow lengths varied between 6-30 years in the region, with families cultivating an average area of 1.6 ha (Borah J R personal observation) plus an uncertain area under communal fallow. Such observations within the study region are consistent with wider trends found in Northeast India (Maithani 2005, Lungmuana et al 2017. All modelling and analyses were conducted using R 3.5.3 (R Core Team 2019).…”

Section: Focal Area and Datasupporting

confidence: 84%

“…For existing 30 year cycles, scenarios 1.1 and 1.2 represent a contraction in fallow length to 15 and 5 year cycles, respectively, thereby facilitating the restoration of 50.0% and 83.3% of the fallow area. This assumes that fallow length contraction minimally impacts food security, with recent consensus favouring that once fallow increases beyond 2 years, yields are unchanged, with complete soil cohesion and nutrient composition recovery , Mertz 2002, Lungmuana et al 2017. Scenario 1.3 models the complete abandonment of the practice in favour of restoration.…”

Section: Management Scenarios For Modellingmentioning

confidence: 99%

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Economically viable forest restoration in shifting cultivation landscapes

Morton

Borah

Edwards

2020

Environ. Res. Lett.

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Shifting cultivation is a predominant land use across the tropics, feeding hundreds of millions of marginalised people, causing significant deforestation, and encompassing a combined area of land ten-fold greater than that used for oil palm and rubber. A key question is whether carbon-based payment for ecosystem services (PES) schemes can cost-effectively bring novel restoration and carbon-sensitive management practices to shifting agriculture. Using economic models that uniquely consider the substantial area of fallow land needed to support a single cultivated plot, we calculated the break-even carbon prices required for PES to match the opportunity cost of intervention in shifting agriculture. We do so in the North-east Indian biodiversity hotspot, where 35.4% of land is managed under shifting agriculture. We found net revenues of US$829.53-2581.95 per 30 ha when fallow area is included, which are an order of magnitude lower than previous estimates. Abandoning shifting agriculture entirely is highly feasible with break-even prices as low as US$1.33 t −1 CO 2 , but may conflict with food security. The oldest fallow plots could be fully restored for US$0.89 t −1 CO 2 and the expansion of shifting agriculture into primary forest halted for US$0.51 t −1 CO 2 , whereas abandoning short-fallow systems would cost US$12.60 t −1 CO 2 . A precautionary reanalysis accounting for extreme economic uncertainty and leakage costs suggests that all interventions, excluding abandoning short-fallow systems, remain economically viable with prices less than US$4.00 t −1 CO 2 . Even with poorly formed voluntary carbon markets, shifting agriculture represents a critical opportunity for low-cost forest restoration whilst diversifying income streams of marginalised communities across a vast area.

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Section: Focal Area and Datasupporting

confidence: 84%

Section: Management Scenarios For Modellingmentioning

confidence: 99%

Economically viable forest restoration in shifting cultivation landscapes

Morton

Borah

Edwards

2020

Environ. Res. Lett.

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“…We did not quantify soil organic carbon as studies from northeast India indicate that soil carbon is resilient to landuse changes from shifting cultivation and recovers rapidly within the first two years of the fallow period (Lungmuana et al 2017). In addition, studies from elsewhere in the tropics also suggest that forest age has negligible influence on soil carbon, which accumulates rapidly and then stabilizes following abandonment (Martin et al 2013, Kotto-Same et al 1997.…”

Section: Carbon Samplingmentioning

confidence: 99%

“…1). We considered a 5-yr cultivation cycle as the shortest cycle, because studies show that, with fertilizer inputs, soil fertility restores within the first two years of fallow ensuring a 5-yr cycle as a viable option for crop cultivation (Thomaz 2013, Lungmuana et al 2017). We did not include conversion to permanent agriculture in scenario predictions as studies suggest that this is not sustainable in this region, in part due to severe soil erosion and nutrient depletion (Grogan et al 2012), and there will often also be cultural impediments.…”

Section: Statistical Analysesmentioning

confidence: 99%

“…Under this scenario, as fallow period declines, the older fallows are spared from cultivation by increasing agricultural intensity of a part of the landscape. Increased intensification (such as the use of chemical fertilizers) would enable food production to be maintained despite shorter fallow period (Lungmuana et al 2017). We estimated carbon stocks when 50%, 67%, and 83% of the landscape were removed from shifting cultivation in 15-yr (Scenario 2.1), 10-yr (Scenario 2.2), and 5-yr cultivation cycles (Scenario 2.3), respectively.…”

Section: Statistical Analysesmentioning

confidence: 99%

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Quantifying carbon stocks in shifting cultivation landscapes under divergent management scenarios relevant to REDD+

Borah

Evans

Edwards

2018

Ecological Applications

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Shifting cultivation dominates many tropical forest regions. It is expanding into old‐growth forests, and fallow period duration is rapidly decreasing, limiting secondary forest recovery. Shifting cultivation is thus a major driver of carbon emissions through deforestation and forest degradation, and of biodiversity loss. The impacts of shifting cultivation on carbon stocks have rarely been quantified, and the potential for carbon‐based payments for ecosystem services (PES), such as REDD+, to protect carbon in shifting cultivation landscapes is unknown. We present empirical data on aboveground carbon stocks in old‐growth forest and shifting cultivation landscapes in northeast India, a hotspot of threatened biodiversity. We then model landscape‐level carbon stocks under business‐as‐usual scenarios, via expansion into the old‐growth forest or decreasing fallow periods, and intervention scenarios in which REDD+ is used to either reduce deforestation of primary or secondary forest or increase fallow period duration. We found substantial recovery of carbon stocks as secondary forest regenerates, with a 30‐yr fallow storing about one‐half the carbon of an old‐growth forest. Business‐as‐usual scenarios led to substantial carbon loss, with an 80% reduction following conversion of old‐growth forest to a 30‐yr shifting cultivation cycle and, relative to a 30‐yr cultivation landscape, a 70% reduction when switching to a 5‐yr cultivation cycle. Sparing old‐growth forests from deforestation using protected areas and intensifying cropping in the remaining area of shifting cultivation is the most optimal strategy for carbon storage. In areas lacking old‐growth forest, substantial carbon stocks accumulate over time by sparing fallows for permanent forest regeneration. Successful implementation of REDD+ in shifting cultivation landscapes can help avert global climate change by protecting forest carbon, with likely co‐benefits for biodiversity.

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Tight coupling of fungal community composition with soil quality in a Chinese fir plantation chronosequence

et al. 2020

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Predicting changes in carbon and nutrient cycles in plantations requires a mechanistic understanding of the effects of stand age on soil quality and microbial communities. Here, we evaluated soil quality by using an integrated soil quality index (SQI) and traced the parallel shifts in fungal community composition using high‐throughput sequencing in a chronosequence of Chinese fir (Cunninghamia lanceolata) plantations (stand age of 3, 16, 25, 32, >80 years). Soil properties showed pronounced changes with stand age in the topsoil. Soil organic carbon (SOC), total nitrogen (TN) and available phosphorus (AP) were 2.1, 1.9 and 2.2 times higher, respectively, in the oldest stands than in the youngest stands. SQI of the top 5 cm increased logarithmically with stand age. Mycorrhizal fungi initially increased in younger stands, but then they were gradually replaced by saprotrophs in older stands due to larger litterfall. Strong positive correlations between saprotrophic fungi and key soil quality indicators, such as TN, AP and NH4+, confirmed that abundance of decomposers is tightly linked with higher soil quality. Mycorrhizal orders Thelephorales, Sebacinales and Russulales increased in abundance and raised the activity of acid phosphatase to mobilise limiting phosphorus from organic matter. Consequently, mycorrhizal fungi are especially relevant in younger stands to acquire nutrients to sustain tree productivity. In developed stands, however, saprotrophic fungi are crucial in recycling nutrients from the litter. Collectively, the increase of topsoil quality during the life cycle of Chinese fir plantations is closely linked with the observed transition of fungal communities from mycorrhizae to saprotrophs.

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Impact of secondary forest fallow period on soil microbial biomass carbon and enzyme activity dynamics under shifting cultivation in North Eastern Hill region, India

Cited by 30 publications

References 36 publications

Economically viable forest restoration in shifting cultivation landscapes

Economically viable forest restoration in shifting cultivation landscapes

Quantifying carbon stocks in shifting cultivation landscapes under divergent management scenarios relevant to REDD+

Tight coupling of fungal community composition with soil quality in a Chinese fir plantation chronosequence

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