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Journal of Resources and Ecology >

2024 , Vol. 15 >Issue 4: 880 - 888

DOI: https://doi.org/10.5814/j.issn.1674-764x.2024.04.009

Impact of Human Activities on Ecosystem

Poplar Plantation as an Agroforestry Approach: Economic Benefits and Its Role in Carbon Sequestration in North India

  • Rajeev JOSHI , 1, * ,
  • Bharat SHARMA 2 ,
  • Hukum SINGH 3 ,
  • Nabin DHAKAL 1 ,
  • Santosh AYER 1 ,
  • Tek MARASENI 4
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  • 1. College of Natural Resource Management, Faculty of Forestry, Agriculture and Forestry University, Udayapur, Katari 56310, Nepal
  • 2. Sustainable Initiatives for the Community (SIFC), Kathmandu 44600, Nepal
  • 3. Forest Research Institute, PO New Forest, Dehradun 248006, India
  • 4. Institute for Life Sciences and the Environment, University of Southern Queensland, Toowoomba, QLD 4350, Australia
* Rajeev JOSHI, E-mail:

Received date: 2023-08-17

  Accepted date: 2024-01-16

  Online published: 2024-07-25

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Abstract

Poplar has gained popularity among farmers of Punjab, Haryana, Western Uttar Pradesh, and the foothills of Uttarakhand and Himachal Pradesh due to their fast growth rate and suitability for industrial uses such as pulp and timber production. Integrating poplar trees into agroforestry systems optimizes land resources and economic gains, as successful techniques have been developed to coordinate crop timing and arrangements effectively. Integrating poplar trees with agricultural crops provides additional income streams for farmers and contributes to soil conservation, biodiversity enhancement, and other environmental benefits. Farmers in these regions typically employ effective spacing of 5 m×4 m for block plantation and 1 m×3 m for row plantation. In the present study, a systematic literature review encompassing 137 English-language journal articles was conducted to assess the economic benefits of Poplar using discounted cash flow (DCF) analysis, considering short-rotation poplar (SRC) and very short-rotation poplar (vSRC) plantations alongside annual crops. The findings revealed that increasing canopy density led to a decline in crop yields by 37%, 70%, and 99% at canopy densities of 30%, 60%, and 90%, respectively, from early spring to harvest. Cost-benefit analysis in Saharanpur district, India, indicated average annual net returns of USD 346.36 for Poplar-based agrisilviculture, while monoculture yielded USD 140.73 per annum. Furthermore, economic analysis in Yamunanagar and Haridwar districts showed benefit-cost ratios ranging from 2.35 to 3.7. Additionally, Poplar block and boundary plantations were found to sequester significantly more carbon in long-lived biomass, serving as substitutes for fossil fuels (5.45 and 1.84 t ha-1 yr-1) in poplar-based systems with block and boundary plantations. The study suggested expanding spacing between tree rows may mitigate resource competition between plantations and crops. The study inferred that Poplar-based agroforestry may play a crucial role in climate mitigation programs by effectively sequestering atmospheric carbon and offering fuel, fodder, timber, and wood products, thereby alleviating pressure on existing natural forests.

Key words： agroforestry; poplar; economic viability; carbon sequestration; India

Cite this article

Rajeev JOSHI , Bharat SHARMA , Hukum SINGH , Nabin DHAKAL , Santosh AYER , Tek MARASENI . Poplar Plantation as an Agroforestry Approach: Economic Benefits and Its Role in Carbon Sequestration in North India[J]. Journal of Resources and Ecology, 2024 , 15(4) : 880 -888 . DOI: 10.5814/j.issn.1674-764x.2024.04.009

1 Introduction

The International Centre for Research in Agroforestry (ICRAF), also known as the World Agroforestry Centre, defines agroforestry as a comprehensive land-use strategy wherein perennial woody plants such as trees, shrubs, palms, and bamboo are integrated within the same land management unit as crops and/or animals. This integration of plan-tation with crops may be spatial arrangement or temporal sequence (Lundgren and Raintree, 1983). In South Asia, particularly in the hills and mountains, over 70% of the population relies on agriculture and natural resources for their rural livelihoods (Rasul and Kollmair, 2010). India, with its rich history of agroforestry, has developed various indigenous systems over the years to address local needs and specific site conditions. Agroforestry research in India began approximately thirty years ago, leading to the development and testing of several agroforestry technologies on farmers’ lands (Chinnamani, 1993). India is home to six native poplar species, namely Populus ciliata, P. euphratica, P. gamblei, P. glauca, P. alba, and P. suaveolens, representing five sections of the Populus genus (Khurana, 1998). Recognizing the significance of these species, India joined the International Poplar Commission in 1965. India established the National Poplar Commission, intending to promote poplar cultivation extensively. Poplar (Populus deltoides) has gained prominence in agroforestry plantations across several states in India, including Western Uttar Pradesh, Uttarakhand, Haryana, Punjab, and Jammu & Kashmir. Carbon stocks and sequestration assessments have become increasingly important for monitoring, reporting, and evaluating agricultural interventions (Thangata and Hildebrand, 2012; Joshi et al., 2020). Trees contribute to dietary diversification, reduce soil erosion, and expand market opportunities for smallholder farmers, but they also hold promise for mitigating climate change and enhancing farmers’ livelihoods (Kumar and Nair, 2011; Van Noordwijk et al., 2011; Kumar et al., 2020; Joshi et al., 2021). However, relying on a limited number of clones in extensive plantations has led to concerns about disease and pest outbreaks and declining clone quality. Ensuring sustained future supplies requires continuously introducing new poplar clones to expand genetic diversity and achieve higher productivity (Chauhan et al., 2008; Kumar et al., 2020).
Furthermore, with increasing carbon emissions becoming a major concern globally, carbon accounting studies in agroforestry systems are gaining importance (Montagnini and Nair, 2004). Poplar-based agroforestry systems have shown higher biomass production, resulting in higher carbon stock, sequestration, and certified emission reduction, contributing to lower net emissions than open farming (Kumar et al., 2020). Minimal studies are available on the financial benefits and carbon sequestration potential of Poplar-based agroforestry, which require addressing issues related to income generation and climate change mitigation by Poplar-based agroforestry system in North India. Therefore, the present study evaluated the financial advantages of poplar-based agroforestry and ascertained its contribution to climate change mitigation by sequestering atmospheric carbon, highlighting the importance of sustainable agroforestry practices for economic and environmental benefits in India.

1.1 Benefits of agroforestry trees

Agroforestry trees offer numerous environmental advantages, with significant ones including: 1) Provision of food and nutrition, 2) Utilization for wood fuel and conservation, 3) Production of a variety of household items, 4) Enhancement of agricultural productivity, 5) Support for livestock, and 6) Influence on micro-climate and climate change mitigation. Fruits, nuts, bark, and roots serve as primary sources of food, providing additional nutrition during dry seasons. Furthermore, they serve as consistent sources of fuel for heating and wood conservation. Additionally, these trees contribute to diverse household products such as construction materials, shading for both people and livestock, farm tools, traditional medicinal herbs for humans and animals, boats, carvings, and furniture. Historical evidence strongly indicates that agroforestry, when integrated into a multifunctional working landscape, not only yields economic returns but also delivers a plethora of ecosystem services and environmental benefits, fostering a sustainable society.

1.2 Economy

Agroforestry significantly bolsters the rural economy by increasing per-unit productivity and generating employment for both unskilled and semiskilled laborers. The cultivated trees serve as a form of financial security for farmers. Optimal intercropping with poplars necessitates careful consideration of plantation density for increased productivity. Wider spacing ensures adequate sunlight for crop growth and proper soil cultivation. Notably, poplars thrive under diligent and frequent soil cultivation rather than just nutrient application.
Further, poplars are intolerant of weed presence, while their root systems demand ample oxygen for optimal development. In India, common spacing configurations for poplar planting, such as 5 m×4 m, 5 m×5 m, 7 m×3.5 m, and 8 m×2.5 m, allow efficient tractor operations (Chandra et al., 2011). Researchers have indicated that poplar-based agroforestry proves economically viable, yielding greater profits with minimal risks compared to other land use alternatives (Jain and Singh, 1999; 2000; Dhillon et al., 2001). Various factors such as tree harvesting age, density and arrangement of plantations, land purpose (forestry or agriculture), clone type, intercropping, plantation management practices, cultural inputs, and market prices for both input materials and farm produce—trees and intercrops—during specific periods influence poplars productivity. Various studies have assessed poplar’s economic viability since its introduction in both forest and farmland. For instance, the initial large-scale poplar plantation on 20 ha of forest land harvested in 1981 yielded a 28 percent internal rate of return and a 3.19 percent B:C ratio at a 13 percent interest rate (Chaturvedi, 1982a; 1982b). Economic returns from poplar cultivation, with or without intercrops, vary with tree rotation periods (Mathur and Sharma, 1983). In an 8-year rotation, a higher B:C ratio of 3.22 was observed for farmland poplar cultivation with intercrops compared to 2.15 for forest plantation with intercrops and 1.51 for forest land without intercrops (Mathur and Sharma, 1983). Dhillon et al. (2001) reported a cost-benefit ratio of 1:1.92 for pure poplar and 1:2.13 for poplar with intercrops. The cost-benefit ratio for farmland at an eight-year rotation was 1.86 and 1.70 for 12 percent and 15 percent discount rates, respectively, accounting for a net loss due to crops against an opportunity cost of USD 60.28 (Chandra, 1986). A five-year-old poplar plantation at a 5 m×4 m spacing intercropped with Mentha under agroforestry yielded net returns of USD 532.486 per ha from trees and USD 790.50 from crops (Chandra et al., 2011). Net returns of USD 132.781 per ha and USD 494.9 per hectare were recorded over three and seven years, respectively, for single-row plantations with field bunds. Cultivating nursery stock yielded significantly higher benefits (100.9%) in the first year. Farmers are reaping substantial profits from nursery and plantation activities, with returns of 38.8 percent and 100.9 percent of investments reported within one year (Singh and Negi, 2001). Benefit-cost ratios of 1.92:1 and 2.13:1 have been estimated for pure poplar and poplar with intercropping in a payback period of seven years (Dhillon et al., 2001). Due to the low risks and substantial gains associated with poplar cultivation, large farmers and absentee landlords favor poplar-based agroforestry over other agriculture/agroforestry options (Kumar et al., 2004).

1.3 Major constraints in agroforestry systems

According to Sharma et al. (2009), it has been observed that farmers in the western districts of Uttar Pradesh are grappling with the issue of receiving low prices for their crops, primarily due to their heavy reliance on intermediaries or contractors. These farmers face challenges challenges, including inadequate crop valuation, burdensome levies laws, the onslaught of epidemic diseases like gall, limited awareness about and adoption of high-yield superior poplar clones, labor scarcity, and concerns about soil fertility and productivity. Furthermore, similar problems have been identified in other regions as well.

1.4 Poplar based agroforestry as a carbon sink

The carbon sequestration potential of agroforestry has gained attention, especially after the Kyoto Protocol recognized it as a greenhouse gas mitigation option (Nair et al., 2009). Albrecht and Kandji (2003) conducted a study analyzing carbon storage data in tropical agroforestry systems, estimating their role in reducing atmospheric CO2. Carbon sequestration potential in such systems varies from 12 to 228 t C ha−1, with a 95 t C ha−1 median. Long rotation systems, like agroforests and boundary plantings, can significantly sequester carbon in biomass and long-lasting wood products. Soil carbon sequestration is also viable in many agroforestry systems. The potential for afforestation/reforestation varies based on ecosystem, species, growth rate, and management, with a reported global potential of 630 million ha of land to sequester 586 t C per year by 2040 (Sharma et al., 2016).
Scholars such as Sharma et al. (2001), Singh and Lodhiyal (2009), Yadava (2010), and Rizvi et al. (2011), have highlighted the substantial potential of poplar-based intercropping systems in reducing atmospheric CO2 concentrations when compared to sole cropping methods. However, there is a lack of comprehensive data and a thorough comprehension of the relationships between plants and climate is imperative to guide future policies. Several studies have been undertaken to explore the carbon sequestration potential within poplar-wheat-based systems. The total assimilation of CO2 by biomass in the poplar-wheat agroforestry system, as well as in monocropping of poplar and wheat, was calculated at 28.6, 17.2, and 17.8 t ha-1 yr-1, respectively (Chauhan et al., 2012) (Fig. 1). Therefore, even when exclusively considering the accumulation of carbon within the biomass, agri-silvicultural systems demonstrate high efficiency in terms of carbon sequestration (Chauhan et al., 2007). It is important to note that these statistics hold true only if harvested products are transformed into durable goods. The decomposition of litter (leaves, branches, and bark) and roots contributes to soil carbon sequestration. Gera et al. (2006, 2012) reported a potential for carbon sequestration of 66 and 37 tons per hectare (equivalent to 2.20 and 1.37 t of carbon per hectare per year, respectively) in poplar block and poplar boundary plantations. Following seven years of poplar growth, Chauhan et al. (2010) estimated a timber carbon content of 23.57 t ha-1.
Fig. 1 Total CO2 assimilation (t ha-1) by poplar-wheat (above- and below-ground biomass) in agroforestry system and sole wheat cultivation (Chauhan and Beri, 2007)
In contrast, the carbon content of roots, leaves, and bark amounted to 23.9 t ha-1, and branches accounted for 15.01 t ha-1. Hence, the cumulative biomass carbon storage after seven years equated to 62.48 t ha-1 (or 8.92 t ha-1 yr-1). The poplar-wheat intercropping system exhibited a notably high combined carbon contribution. This can be attributed to the additional carbon pool within the trees and the enhanced soil carbon pool resulting from litter deposition and the turnover of fine roots. The elevated carbon storage may also be attributed to the increased growth and assimilation rates of components within the intercropped system instead of monocropping methods. Furthermore, poplar timber effectively sequesters carbon within its wood products for extended durations, establishing it as a critical carbon assimilator within this agroforestry system. Consequently, the poplar-wheat agroforestry system is superior to traditional agricultural systems, presenting an optimal land use choice for enhanced carbon sequestration (Fig. 1).

2 Methodology

2.1 Methods of assessing economic benefits from poplar

To evaluate whether certain cultivation is favorable or not, the discounted cash flow (DCF) method was applied by comparing SRC and vSRC poplar plantations with an annual crop, as in other studies. Therefore, the net present value (NPV) of the overall plantation was calculated according to the following formula:
$~NPV=\underset{k=0}{\overset{n}{\mathop \sum }}\,\frac{Ck}{\left( 1+r \right)\times k}$
where, NPV is discounted annual cash flows; Ck represents the annual cash flow, obtained from the difference between the annual inflows and the annual outflows; k is the time of the cash flow; n corresponds to the lifetime of investment (equal to 14 years for vSRC and 15 years for SRC); r is the discount rate and it was assumed equal to Weighted Average Cost of Capital (WAAC) with a value of 5%. Hence, to compare poplar plantations with wheat, from (1) it has been calculated the annual gross profit (or annuity), which divides all costs and incomes into average annual values:
$a=NPV\times \frac{r\times \left( 1+k \right)\times k}{\left( 1+r \right)\times k-1}$
where, a is the annuity of SRC and vSRC, NPV is discounted annual cash flows, r is the discount rate and k corresponds to the lifetime of the investment. So, the poplar biomass plantation will be convenient for farmers if the annual gross margin will be higher than the wheat one.

2.2 Literature search

We followed the systematic review process and searched for peer-reviewed articles published between 1982-2020 using three electronic databases: Google Scholar; Web of Sciences; and Scopus. We used the terms Poplar Plantation as an Agroforestry Approach OR Poplar Plantation in India in our searches. In total, we found 752 articles in different electronic databases.

2.3 Selection criteria

We examined the title, abstract, and keywords of each paper, and research articles primarily researching Poplar and research articles analyzing data on Poplar from secondary sources (survey data, records) were only included (Fig. 2). Research findings on Poplar are also communicated in books, conference proceedings, and grey literature. Therefore, we have focused on the peer-reviewed articles in academic journals because they provide the highest level of quality control, and scientific credibility (Fox and Diezmann, 2007) and help ensure uniformity in research standards and methodological details including consistency in sampling and analytical methods (Ballantyne and Pickering, 2015). The first step generated 752 articles. Secondly, these articles were screened for publication type and only the peer-reviewed journal articles were included. Thirdly, the duplicates were removed, and the articles were screened by reading titles and abstracts. Articles that did not have a Poplar as a primary focus of the study were excluded and (n=137) were included in the study.
Fig. 2 Flowchart of the study and steps followed during the review process

2.4 Data analysis

Collected data was classified into social and economic categories. The social factors included age, gender, education and occupation of the household head, employment status, family size and location,rate of acquaintance with agroforestry systems, agricultural techniques and interests on Poplar Plantation and, etc. Economic questions included the total area of the farmer’s farm, the area of the farm under cultivation, the resources of providing seed, fertilizer and pesticide consumption, the farm costs, including the costs of planting (i.e., ploughing, costs of providing seed and fertilizer), costs of labour, pesticides and herbicides, harvesting and so on, the amount of production per unit area and the price of the produced crop in the market. The collected data were analyzed by using Microsoft Excel.

2.5 Carbon estimation

The first one is the destructive method of tree biomass estimation. Among all the available biomass estimation methods, the destructive method, also known as the harvest method, is the most direct method for estimating above- ground biomass and the carbon stocks stored in the forest ecosystems (Gibbs et al., 2007). This method involves harvesting of all the trees in the known area and measuring the weight of the different components of the harvested tree like the tree trunk, leaves and branches and measuring the weight of these components after they are oven dried (Ravindranath and Ostwald, 2008). This method of biomass estimation is limited to a small area or small tree sample sizes. Although this method accurately determines the biomass for a particular area, it is time andresource-consuming, strenuous, destructive and expensive, and it is not feasible for a largescale analysis. This method is also not applicable for degraded forests containing threatened species (Montes et al., 2000). Usually, this method is used to develop biomass equations for assessing biomass on a larger-scale (Navar, 2000). The second method of tree biomass estimation is the non-destructive method. This method estimates the biomass of a tree without felling. The non-destructive method of biomass estimation is applicable for those ecosystems with rare or protected tree species where harvesting of such species is not very practical or feasible. Montès et al. (2004) developed a non-destructive method for the above-ground biomass estimation of Juniperus thurifera L. woodlands in the High Central Atlas, South of Morocco. In this study, the biomass of the individual tree was estimated by considering the tree shape (by taking two photographs of the tree at orthogonal angles), physical samples of different components of the trees like branches and leaves and dendrometric measurements, volume and bulk density of the different components. Although it is a non-destructive method, the trees had to be harvested and weighted to validate the estimated biomass. Another way of estimating the above-ground forest biomass by non-destructive method is by climbing the tree to measure the various parts (Aboal, 2005) or by simply measuring the diameter at breast height, height of the tree, volume of the tree and wood density (Ravindranath and Ostwald, 2008) and calculate the biomass using allometric equations. Since these methods do not involve the felling of tree species, it is not easy to validate the reliability of the method. These methods can also involve a lot of labour and time and climbing can be troublesome.

2.6 Methods of measuring each pool of carbon

The main variables involved in this study are:
a) Above Ground Biomass (AGB)
• Bole mass = Volume × Wood density
• Above Ground Biomass = Bole mass × Biomass expansion factor
• Total carbon (T1) = AGB × 0.47
b) Below Ground Biomass (BGB)
• Below Ground Biomass = AGB × 0.26
• Total carbon (T2) = BGB × 0.47
c) Deadwood (Dead organic matter)
• Deadwood biomass = (AGB + BGB) × 0.11
• Total carbon (T3) = Deadwood biomass × 0.47
d) Leaf Litter, Grass and Herb (LGH)
All under storey bushes, grasses, and herbaceous layers can be clipped and weighed. Clipped samples can be dried inside the oven at a temperature of 102 degrees centigrade for 24 hours. The following formula can be applied to calculate the biomass value of leaves, litter, twigs, grass, and herbs (Lasco et al., 2005).
$~ODW=\frac{TFW-TFW\times \left( SFW-SODW \right)}{SFW}$
where, ODW is total oven dry weight; TFW is total fresh weight; SFW is sample fresh weight; SODW is sample oven dry weight. The carbon content in LHG can be calculated by multiplying LHG with the IPCC (2006) default carbon fraction of 0.47. T5= ODW(t)×0.47. Total carbon content in all pools is:
T = T1+ T2+ T3+T4+ T5.
where, T1 is total carbon contained in 1st pool; T2 is total carbon contained in 2nd pool; T3 is total carbon contained in 3rd pool; T4 is total carbon contained in 4th pool; T5 is total carbon contained in 5th pool.
Total carbon sequestration in forest ecosystem= Total carbon×3.6663
e) Bulk density
Metal core ring sampler of dimension, 9.7 cm length and 3.86 cm diameter can be used to determine the soil samples' bulk density along the soil profile. The fresh soil extracted by the metal core ring sampler can be bagged in plastic bag, sealed, leveled and transported to the laboratory for the determination of oven oven-dry weight and the Bulk density can be computed using the following relations:
$~Bulk\text{ }density(\text{gm c}{{\text{m}}^{}}^{3})=\frac{oven\text{ }dry\text{ }weight\text{ }of\text{ }the\text{ }soil}{volume\text{ }of\text{ }the\text{ }core}$
T4= Soil Organic Matter Carbon
f) Soil Organic Matter (SOM)
The Walkey-Black method is applied to measure the soil organic carbon percent (Joshi et al., 2021). The formula below can calculate Total soil organic carbon (SOC, Chabbra et al., 2002).
SOC=Organic carbon content (%)×soil bulk density(kg m–3) × horizon thickness (cm)
SOC is expressed in t ha-1.

3 Results and discussion

Tiwari (1968) noted a significant decrease in wheat crop yield when grown alongside poplar trees. Still, contrary observations were made by Sheikh et al. (1983) and Sharma et al. (2001), who found no substantial impact of poplar tree competition on wheat crop resources. On the other hand, Dhadwal and Narain (1988), reported a yield increase in crops adjacent to poplar trees planted along boundaries rather than in block plantations. Pendleton and Weibel (1965) demonstrated a reduction in crop yield with increasing shading levels, reporting 37%, 70%, and 99% decreases at 30%, 60%, and 90% shading, respectively, from early spring to harvest. The expansion of spacing between tree rows has been found to mitigate resource competition (Chauhan and Dhiman, 2002). While a 5 m×5 m spacing balances crop yield and tree productivity, a 5 m×4 m configuration is favored for accommodating more trees, ensuring better overall economics with minimal loss to crops and trees (Gandhi and Dhiman, 2010). Row spacing directly influences crop and tree productivity, impacting light availability for under-storey crops (Chauhan and Dhiman, 2002), and there exists a strong correlation between stem volume/basal area and crown surface area (Mishra and Gupta, 1993). In a study conducted by Dwivedi et al. (2016) on cost-benefit analysis of poplar-based agri-silviculture in Saharanpur district, India, the average annual net returns were calculated at USD 346.40, while pure crop rotation yielded only USD 140.75 per annum. Jain and Singh (2000) investigated the performance of Poplar-based agroforestry in Shahjahanpur district of western Uttar Pradesh, highlighting its economic viability and profitability over various crop rotations. This land use system also presented employment opportunities (Chahal et al., 2012), recording the highest net income in poplar + sugarcane (USD 771.94 ha-1 yr-1) and poplar + turmeric (USD 714.14 ha-1 yr-1), followed by poplar + rainfed wheat (USD 224.51 ha-1 yr-1) and poplar alone (USD 42.13 ha-1 yr-1). The traditional rice-wheat crop rotation yielded 275.49 ha-1 yr-1 as net income. Deswal et al. (2014) found that poplar-based agroforestry provided farmers with a 46% higher income than rice-wheat crop rotation. Chaturvedi and Pandey (2001) estimated the B:C ratio for poplar-based agroforestry systems in eastern India, with ratios of 5.1 for maize-wheat-turmeric and 6.8 for poplar with pigeon pea-turmeric in a 10-year rotation. Kumar et al. (2004) studied agroforestry models in Yamunanagar and Haridwar districts, determining their economic viability with benefit-cost ratios ranging from 2.35 to 3.73. Similarly, Karnatak (1996) reported that farmers in Yamunanagar District pursued a six-year rotation of sugarcane, wheat, and jowar/potato crops under poplar agroforestry systems, resulting in favorable economic returns. It was found that farmers in Saharanpur and Yamunanagar districts opted for poplar planting at 5 m×4 m or 4.5 m×4.5 m spacing in agri-silviculture and 2 m spacing in boundary systems. According to Kumar et al. (2012), Populus deltoides exhibits a high growth rate (mean annual increment of 20 to 25 m³ ha-1 yr-1) in India, particularly when intercropped with intensive irrigation and culturally demanding agricultural or horticultural crops.
Gera (2012) conducted studies on poplar block and bund plantations and found that they have a sequestration potential of 1.33 tC ha-1 yr-1 and 1.05 tC ha-1 yr-1, respectively, when excluding wood products and 2.41 tC ha-1 yr-1 and 1.80 tC ha-1 yr-1, respectively, when considering wood products. The sequestration potential is influenced by the Mean Annual increase (MAI) of tree growth, which includes above and below-ground biomass growth, measured in t ha-1 yr-1. The density of plantations also affects MAI, leading to lower sequestration potential in bund plantations compared to block plantations of the same species. This is supported by Hooda et al. (2007), who reported a sequestration potential of 1.98 tC ha-1 yr-1 for poplar block plantations in a similar area of Uttarakhand. Other studies, such as Gera et al. (2006), reported sequestration potentials of 2.54 tC ha-1 yr-1 for poplar block plantations and 1.42 tC ha-1 yr-1 for bund plantations in farmlands of Rupnagar, Punjab. Ravindranath et al. (2007) found an average sequestration potential of 2.23 tC ha-1 yr-1 for short rotation interventions with fast-growing species like Eucalyptus, Casuarina, Acacia, and Gmelina arborea, planted for fuel wood, industrial wood, and poles. Makundi and Sathaye (2004) reported similar sequestration potentials of around 1.55 tC ha-1 yr-1 for agroforestry species. A study by Updegraff et al. (2004) in Minnesota, USA, estimated sequestration levels of 1.8 to 3.1 tC ha-1 yr-1 for short-rotation hybrid poplar plantations. Gupta et al. (2009) observed that soil organic carbon increased from 0.36 to 0.66 percent in P. deltoides (poplar) based agroforestry soils, and the increase was more pronounced with tree age. Soils under agroforestry had 2.9- 4.8 t ha-1 higher soil organic carbon compared to sole crop. Poplar trees sequestered more soil organic carbon in the 0-30 cm profile during the first year of plantation (6.07 t ha-1 yr-1) than in subsequent years (1.95-2.63 t ha-1 yr-1). The soil type also influenced sequestration, with sandy clay soil sequestering more carbon (2.85 t ha-1 yr-1) than loamy sand (2.32 t ha-1 yr-1). Poplar plantations also helped control soil erosion by increasing the dispersion ratio, erosion ratio, and water-stable aggregates with plantation age.
However, it’s noteworthy that less than half of the total timber is conserved for extended periods, while the remaining biomass is utilized as fuel, replacing fossil fuels and contributing to carbon sequestration for energy purposes (Table 1). It was observed that poplar block and boundary plantations sequester a significant amount of carbon in long-lived biomass and serve as a substitute for fossil fuels (5.45 and 1.84 t ha-1 yr-1 in poplar-based systems with block and boundary plantations, respectively) (Chauhan et al., 2012). In a study by Panwar et al. (2017), the simulated total biomass after a single 9-year rotation of P. deltoides ranged from 110.5 to 136.6 Mg ha-1 without a crop and 122.4 to 152.7 Mg ha-1 when crop production was included. This simulated biomass is comparable to the 128.6 Mg ha-1 reported by Rizvi et al. (2011) in the 7th year of a plantation with a similar density. Lodhiyal et al. (1995) reported a 134.3 Mg ha-1 biomass in an 8-year-old plantation, albeit with a lower plant density. In contrast, Dar and Sundarpandian (2015) documented higher biomass values (254.3 Mg ha-1) and carbon content in a poplar forest in the temperate Himalayas, attributed to a higher plant density (1201 tree ha-1). Arora et al. (2014) reported a biomass production of 180.2 Mg ha-1 in an 11-year-old plantation. Regarding carbon stocks, Panwar et al. (2017) revealed that the simulated carbon stocks for six and 9-year rotations of P. deltoides ranged from 41.9 to 47.5 Mg ha-1 and 73.2 to 88.4 Mg ha-1, respectively. Similarly, low carbon stocks of 23.2 Mg ha-1 at 9 years of age have been reported by Yadava (2010). Additionally, at the 9-year mark, comparable carbon stocks of 75.3 Mg ha-1 were reported by Arora et al.
Table 1 Carbon sequestration in poplar-based agroforestry models
Treatments* Total biomass** (t ha-1) Carbon
storage		 Long-lived timber combustion (109 tC ha-1) Heat from biomass coal substitute (tC ha-1) Carbon storage from sequestration*** Total C sequestration
(tC ha-1 yr-1)
Block Trees + wheat straw 154.3 18.7 2041.4 34.3 55.4 9.2
Plantation Trees without wheat straw 125.7 18.7 1525.7 25.6 46.8 7.8
Boundary plantation Trees +wheat + rice straw
Trees + rice straw		 101.8
72.8		 4.4
4.4		 1657.4
1135.8		 27.8
19.1		 32.7
23.9		 5.5
4.0
Trees without rice and wheat straw 30.1 4.4 367.9 6.2 11.0 1.8

Note: * Calculations were made with the presumption that wheat straw is used as fodder, whereas rice straw is used as fuel; ** tree and crop (grain + straw) biomass; *** includes soil as well as long lived carbon storage in timber.

4 Conclusions and recommendation

The primary driving force behind adopting commercial agroforestry in India was the assurance of a steady incom. In contrast, the traditional agroforestry systems on farmlands were predominantly motivated by fuelwood availability. In comparison, commercial agroforestry systems based on Poplar have demonstrated higher profitability than traditional agroforestry systems and conventional crop patterns. The incorporation of trees into farming practices not only added diversity to the livelihoods of farm households by generating income and employment but also fulfilled the demand for wood. Both forms of agroforestry play distinct roles in supporting livelihoods and industrial development, and their sustainability requires careful nurturing. This approach is vital for enhancing diminishing forest cover and meeting the escalating wood demands of wood-based industries. A deeper understanding of the factors influencing farmers’ long-term land use decisions is needed to unlock the potential of poplar-based agroforestry. To ensure the profitability of agriculture in general and poplar-based agroforestry systems in particular, alignment with market and industry needs is essential. The key to sustaining these systems profitably lies in standardizing the cultivation of clones highly valued by industries. Integrating shade-loving species and intercropping high-value crops such as flowers, vegetables, aromatics, and medicinal plants with poplars is imperative to anticipate the future landscape. There is significant potential for expanding poplar cultivation in the Northwestern states of the country, which can elevate farmers’ socio-economic status while meeting industrial demands. This system synergizes vital resource sharing—light, water, and nutrients—while sequestering substantial carbon in both wood and soil. Proper management and care of plantations are crucial to harnessing optimal productivity from poplar trees. Continuous short-rotation commercial tree cultivation can also enhance soil health and bring environmental and economic benefits.
An intriguing prospect emerges in the agriculture and forestry sectors. The development of Carbon sequestration projects and the sale of resulting emission reduction credits to major industrial emitters. Large emitters might be inclined to purchase credits from these sectors if the cost is lower than the expense of implementing measures to reduce their emissions. In this context, individual agricultural producers may find value in adopting practices like agroforestry that help sequester greenhouse gases, offering carbon reduction credits for sale to emissions-heavy industries that have exceeded their emission limits. In this manner, poplar plantations significantly contribute to the assimilation of atmospheric CO2, playing a vital role in mitigating the accumulation of greenhouse gases. Various programs such as Kisan Nurseries, Kisan Ghosties, and Agreement policies for joint cultivation of significant crops like Poplar, Eucalyptus, and Bamboo could benefit farmers, enhancing their earnings, livelihoods, and overall quality of life. Such programs should be initiated through State Governments, allowing farmers to avail themselves of the benefits offered by their crops. This proactive approach will elevate productivity levels and expand forested areas.

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