Climate plays a crucial role in agricultural productivity, making it unsurprising that intentional microclimate modification has existed as long as agriculture itself. One technology for this, is the introduction of windbreaks and shelterbelts. According to UNCCD, shelterbelts are “Belts of trees, planted in a rectangular grid pattern or in strips withinand on the periphery of, farmland to act as windbreaks.” These are essential agroforestry practices grouped under the agri-silviculture system that offer numerous environmental, social and agricultural benefits, particularly in arid, semi-arid and also coastal regions including reduction of wind speed, minimizing damage caused by high-velocity winds, decreasing soil erosion, reduction of temperature, soil water loss and transpiration; and overall creation of favorable microclimates especially in harsh conditions for crop production. Windbreaks that provide shade and shelter have been utilized to create more productive microclimates and have significant potential to enhance livestock and pasture. They also act as alternate habitats for wildlife and birds. Consequently, planting tree windbreaks is regarded as an effective strategy to combat land degradation and improve agricultural output. The windbreaks or shelterbelts are also known by other terms depending on its purpose as hedgerows or vegetated environmental buffers or living snow fences. According to
Gupta (1997), a shelter belt is a longer barrier than a wind break and is typically made up of trees and plants; while wind break is any kind of barrier used to protect against winds. Though both terminologies ‘shelterbelts’ and ‘windbreaks’ are used in different studies across India, for the purpose of this review, all the terms are used synonymously, as also concluded in the study by
Ramanan et al., (2022).
Standardization of shelterbelt technology started after the United Nations launched the Plan of action to Combat Desertification (PACD) programme in 1977, keeping in view the growing problem of desertification globally (
Harsh and Tewari, 1997). In literature, the concept of protecting agricultural fields from wind can be traced back to the mid-15th century when the Scottish Parliament encouraged farmers to plant trees within their farm boundaries to shield their crops (
Droze 1977). In the 1930s, the importance of shelterbelts became particularly evident after the severe dust storms of the Dust Bowl, which blanketed the Great Plains of the USA in dust, dirtand sand. The Great Plains Shelterbelt was a project to create windbreaks in this region, that began in 1934, initiated by President Franklin D. Roosevelt and led by the U.S. Forest Service. Similar shelterbelt and windbreak programs have emerged in various countries, including government led programs like Australia’s National Windbreak Programme in 1993 and China’s ‘Three Norths Forest Shelterbelt’ program stating in 1978
(Ramanan et al., 2022). trainings on windbreak/shelterbelt establishment such as the online courses provided by the Minnesota Board of Water and Soil Resources US, publication series such as Shelterbelts for livestock farms in Alberta: planning, planting and maintenance by the Alberta Government and even private players such as the Prairie Shelterbelt Program, Canada. The studies on shelterbelts/ windbreaks have been done since long in several countries. Literature review leads us to conclude that major research works published on shelterbelts/ windbreaks are from China (55%), followed by the USA (9%) as per Web of Science database.
In India, work on shelterbelts for reduction of wind erosion gained momentum with the establishment of the ‘Desert Afforestation Research Station’ at Jodhpur in 1952 by the Government of India, fearing the spread of the desert to areas like the national capital, Delhi (
Yadav, 2018). In India, where approximately 33% of the land area is classified as arid or semi-arid, the implementation of these shelterbelts/ windbreaks is vital for mitigating the adverse effects of wind erosion, improving soil moisture retentionand enhancing crop yields. From this, spread throughout the states of Rajasthan (61.9%), Gujarat (19.6%), Haryana and Punjab (8.6%)andhra Pradesh (6.8%), Karnataka (2.7%) and Maharashtra (0.4%) (Fig 1), the hot and arid region of India spans approximately 31.7 million hectares
(Mertia et al., 2006; Meghwal et al., 2022). Characterized by extreme temperatures (0-50°C), low (100-400 mm) and variable rainfall (CV>50), high wind speeds, low humidityand frequent droughts, combined with the light sandy soil’s limited water retention capacity and deficiency of nutrients, agricultural production in the hot arid zone is limited and risky. In arid zones, especially in northwestern regions, from March through September, there is a significant wind pattern that includes strong, dusty winds in May, June and July. According to
Prasad et al., (2009), the area’s highest daily wind velocity often reaches 30-45 km/hr in June and July, with peak winds reaching up to 100 km/hr during severe dust storms. Strong winds bury agricultural fields and obstruct highways with the deposition of flying soil particles, while also taking away fertile topsoil and inflict irreversible losses in production.
Shelterbelt research in India began to increase in prominence around the 1960s, initiated by
Bhimaya et al., (1958), Bhimaya and Chowdhari (1961),
Raheja (1963) and
Ganguli and Kaul (1969) who recommended different types of shelterbelts for fields and road side plantations mainly in the arid areas of Rajasthan (
Gupta, 2000). This period saw increased awareness of the importance of shelterbelts in controlling wind erosion, improving microclimatesand enhancing agricultural productivity, especially in arid and semi-arid regions. With the major contribution of micro windbreak construction, CAZRI has been developing sand dune stabilisation techniques since 1961. The Forest Department of Rajasthan has stabilised over 90,000 hectares of land with this technology (
Harsh and Tewari, 1997).
Mertia et al., (2006) in studies done in hyper arid Jaisalmer region of Rajasthan reports the beneficial role of shelterbelts in lowering air temperatures, increasing humidity and reducing evapotranspiration, besides improving soil organic carbon.
The role of shelterbelts and windbreaks in the arid, semi-arid and coastal zones is unmatched. This review synthesizes research done on windbreaks and shelterbelts established for agricultural purposes in India and particularly the arid regions from 1958 to present, showcases few successful case studiesand outlines future research pathways.
Methodology
A comprehensive search for relevant studies was conducted using Web of Science and Google Scholar. The search terms included windbreaks and/or shelterbelts; with keywords ‘crop’, ‘growth’ ‘soil’ and ‘arid’. Studies conducted in India, as per WoS was only 2%. When we filtered the studies to include only those conducted in India and published in English, using Web of Science, we got only 6 publications. Hence, Google Scholar was further used for obtaining relevant research.
Importance of windbreaks and shelterbelts
Recognizing the irreplaceable role of shelterbelts and windbreaks in the rehabilitation of denuded arid and semi-arid lands in Rajasthan desert,
Bhimaya and Kaul (1960) reports the progress in research towards this end including species selection and suitable afforestation techniques going on at Desert Afforestation and Soil Conservation Station, Jodhpur. According to IPCC report (2021), climate models project that the Earth’s average global temperature could rise by an additional 4°C (7.2°F) in the twenty-first century. Climate change, is also expected to cause great variations in temperature and also affect type, frequency and intensity of extreme weather events
(Patel et al., 2023), such as heat waves, rainfall fluctuations, dust storms, cyclones
etc. which are more serious in the case of arid, semi-arid and coastal areas. Some studies indicate that by 2050, certain regions may experience a 5-20% rise in temperature and rainfall from December to February, while seeing a decrease in rainfall of the same magnitude between June and August
(Hulme et al., 2005). These temperature increases are expected to negatively affect most crops, especially in arid regions. Smallholder farmers, lacking financial and irrigation resources, might turn to natural systems to gain ecological benefits as a strategy to mitigate the uncertainties posed by climate change. Agroforestry systems, such as shelterbelts, characterized by their diverse components, can enhance resilience of the farming system
(Bhimaya et al., 1958; Gupta, 2000). These windbreaks can create more suitable microclimates moderating high velocity winds and extreme temperatures and shielding the understorey from the adverse weather during the day; while at night, the canopy helps retain warmth, safeguarding crops from frost damage in winter. In agricultural systems, windbreaks enhance crop quality and marketability by minimizing crop damage from wind-blown particle abrasion and preventing fruit from rubbing against other plant parts during strong winds. They also facilitate increased honey bee foraging during high winds
(Hennessy et al., 2020) and shelter livestock during adverse weather
(Sheetal et al., 2020). Moreover, these systems help mitigate soil erosion, improve water-use efficiency and improve soil fertility
(Prajapati et al., 2024).
In coastal areas, creation of shelterbelts can disperse the energy of the waves, check ingress and flooding debris to a significant leveland reduce the chances of severe consequences
(Dobhal et al., 2024). A very long, properly designed and successful shelter belt was planted in 1964 along the sea coast of Orissa in east India, which was found very effective against coastal land degradation by hurricanes, cyclones and super cyclones (
Samra, 2020).
Windbreaks are also valued for their broader ecosystem services, which extend beyond the farm. These benefits include enhanced biodiversity, carbon storageand mitigate greenhouse gases
(Chavan et al., 2023; Manasa et al., 2022; Mayrinck et al., 2019). In addition, the system yields various outputs, including food, fuelwood, fodder, fertilizerand timber, which collectively enhance farm incomes through improved and sustained productivity
(Sheetal et al., 2020). The diverse benefits and year-round production of by-products provided by trees planted in windbreaks help mitigate the risk of crop failure, a common issue in monocropping systems, especially in the arid zones. Additionally, incorporating trees into agricultural farms promotes more efficient nutrient recycling, as deep-rooted trees improve nutrient retention on-site while reducing surface runoff and nutrient leaching
(Prasad et al., 2013).
Review of available literature on research done on shelterbelts or windbreaks is summarized in Table 1. Only those research papers have been considered which had data on crop yields, or water use or wind velocity and other related parameters.
Research landscape in shelterbelt and windbreak research
Research on windbreaks and shelterbelts in India has expanded over the last few decades, focusing on species selection, design configurationsand management practices tailored to local conditions. Initiating from the need to stabilize deserts and reduce erosion, the research focus has moved over to integration of these systems in to farming system as boundary plantations in order to harvest all benefits of the tree based ecological system, especially in the fragile north western arid and hyper-arid regions. The success of such systems depends on the species chosen, the planting geometry and pattern and management practices; which have been detailed below:
Species selection
Studies emphasize the use of native species, such as
Prosopis cineraria,
Acacia nilotica and
Ziziphus jujuba, which are well-adapted to arid conditions. Research shows that mixed-species plantations outperform monocultures in terms of biodiversity and resilience. The trees, shrubsand grasses suitable for establishing a silvipastoral system include
Acacia tortilis, Acacia senegal, Prosopis cineraria, Ziziphus nummularia, Calligonum polygonoides, Acacia jacquemontii, Cenchrus ciliaris, Lasiurus sindicusand
Cenchrus seligerus. Additionally, the architecture and phenology of these trees are crucial factors (
Singh, 1996). For instance,
Dalbergia sissoo has a broad canopy with numerous branches and a slow rate of leaf fall, resulting in significant shading that can impact yield. This effect is most pronounced near the tree belt, where decomposing leaves may release phytotoxic chemicals through leaching or microbial processes, potentially inhibiting or delaying germination and initial growth
(Kohli et al., 1997). Research has shown that leaf litter from
Populus deltoides can release allelochemicals that adversely affect crops (
Singh 1996;
Kohli et al., 1997). Similarly,
Soni et al., (2021) suspects the presence of allelopathic compounds in leaf litter of
Acacia senegal and
Acacia tortilis leading to reduction in mustard yields.
According to
Kaul (1996), when selecting plants for afforestation, desirable species should have the following characteristics: (a) a mix of plants with deep vertical roots to access moisture from lower zones and shallow roots to utilize surface moisture after light rains, while also exhibiting a high root binding index; (b) resilience against the abrasive forces of blown sand and high wind velocities; (c) tolerance to extreme temperatures, both frost and heat; and (d) the ability to regenerate naturally.
According to
Sheetal et al., (2020), the preference for shelterbelt species has shifted from previously preferred fast-growing species to economically beneficial timber or horticultural trees like
Dalbergia sissoo, Zyziphus mauritiana,
etc.
The effectiveness of shelterbelts in reducing the wind velocity depends on velocity, direction of wind, site conditions and also on canopy growth, design and geometry of shelterbelts. Optimal spacing and height of windbreaks have been explored to maximize their effectiveness. For instance, staggered rows have been shown to improve wind reduction and enhance the protective benefits for adjacent crops.
Shelterbelts should ideally have a triangular cross-section or a pyramidal structure, with the tallest trees positioned in the center row, flanked by medium-height treesand bushy plants in the outer rows. To prevent tunneling effects, these trees should be planted in a staggered or zig-zag arrangement. To ensure year-round wind protection, it is essential to include both evergreen and deciduous trees in the shelterbelt. There should be adequate spacing between fast- and slow-growing trees to avoid competition. Shelterbelts established in pyramidal shape such as of
Prosopis juliflora, Azadirachta indica and
Albizzia lebbek as three row shelterbelt along the highways were found suitable in desert areas (Kaul, 1985). For spacing, (i) the distance between rows should be a minimum of 2.4 meters and a maximum of 7.6 to 9.1 metersand (ii) within each row, shrubs should be spaced a minimum of 0.9 meters apart, while tall trees can be spaced up to 6.1 meters apart. Shelterbelts are typically planted at right angles to the prevailing wind direction. Successful examples include shelterbelts of
Acacia nilotica var. indica and
Dalbergia sissoo established in the early 1960s over a length of 1-2 kilometers at the Central Mechanized Farm in Suratgarh, Bikaner district, by the Central Arid Zone Research Institute in Jodhpur. In the 1970s, three rows consisting of
Acacia tortilis,
Cassia siameaand
Prosopis juliflora as flank rows, with
Albizia lebbek as the central row, were established at CAZRI, Jodhpur.
The plantations are to be taken up after proper consideration of the tree-crop-water dynamics at the site. Lack of proper planning, a poor understanding of tree-crop interactions and the urge for rapid gains, have led to farmers facing severe economic losses.
Singh and Kohli (1992) highlight the case of large-scale plantations of Eucalyptus undertaken by farmers leading to huge losses to crop.
Trends in shelterbelt research
Over the decades, research in India has evolved from basic establishment and soil conservation strategies to a broader understanding of windbreaks as multifunctional systems that emphasize sustainable cropping, biodiversityand climate resilience. These trends reflect a growing recognition of the multiple roles that shelterbelts and windbreaks play in sustainable land management. According to Table 1, the research has been mainly concentrated in the arid zone of Rajasthan, with some research also done in semi-arid parts of Haryana and Punjab. Here’s an overview of trends in shelterbelt and windbreak research in India from the 1960s to the present, along with suitable references for each period:
l
Initial Studies and Implementation
Early research emphasized the establishment of shelterbelts to combat soil erosion and wind damage, particularly in arid and semi-arid regions. The planting details of
Acacia nilotica and
Dalbergia sissoo shelterbelts along the roadways and railway tracks, as well as at Central Mechanised Farm in Suratgarh, were covered by
Bhimaya and Chowdhari (1961).
Gupta (2000) discusses the plantation of three types of shelterbelts at Jodhpur comprising of three rows:
Acacia tortilis - Albizzia lebbek - Acacia tortilis, Cassia siamea - Albizzia lebbek- Cassia siamea, Prosopis juliflora - Albizzia lebbek -Prosopis juliflora. The central row comprised of tall growing Albizia lebbek forming pyramidal structures. Pyramid-shaped, three- or five-row shelterbelts were designed, depending on the level of wind erosion hazard utilizing above-mentioned tree species and also native shrubs (
Yadav, 2018). By the 1980s, focus shifted to wind speed reduction studies due to the shelterbelts and related benefits including evaporation reduction and reduction in soil erosion
(Gupta et al., 1983; Gupta and Ramakrishna 1988).
l
Integration into agroforestry systems
The integration of shelterbelts into agroforestry systems gained momentum, recognizing their role in enhancing agricultural productivity and sustainability.
Harsh and Tewari (1997a) discusses the plant species suitable for micro windbreaks in dune systems according to rainfall.
Vashishtha and Prasad (1997) discusses the different tree, shrub, fruit trees and grass species suitable for shelterbelt plantation according to rainfall zone in horti-silvi-pasture systems.
l
Research on shelterbelt-based cropping systems
Increased attention on using diverse and native species for shelterbelts to improve ecological balance and resilience against climate variability. The effect of use of different tree species on system, crop growth and yield, water use parameters and economics of the system were prioritized. Research towards understanding the role of shelterbelts in climate change mitigation, with an emphasis on their ability to reduce wind speed and protect crops is also emphasized. The potential of revenue through carbon capture to increase farmers’ profits from agroforestry plantations is also being evaluated by current research
(Singh et al., 2024).
Notable case studies of shelterbelt implementation
The Thar Desert, Rajasthan
In this region, the introduction of shelterbelts has been instrumental in combating desertification. With the advent of Indira Gandhi Nahar Pariyojna (IGNP) massive afforestation work on shelterbelts has been done in Western Rajasthan. According to an estimate about 278 Rkm (Running Kilometer) shelterbelts covering an area of about 9271 ha has been successfully planted in IGNP command area of Jaisalmer district
(Mertia et al., 2006).
In a paper by
Gajja et al., (2007), primary data was collected from 80 farmers each from shelterbelt and non-shelterbelt, selected randomly from tubewell and canal command area of IGNP Phase-II in Mohangarh tehsil of Jaisalmer district. The study found that net returns increased by 430.8% as a result of shelterbelt plantation. Of this increase, 399.4% can be attributed to the use of shelterbelt technology, while 31.4% resulted from greater use of complementary inputs. Within the 399.4% attributable to shelterbelts, 305.6% was directly linked to the transition from non-shelterbelt to shelterbelt systems, while the remaining 93.8% reflects improvements in input usage among non-shelterbelt areas, likely due to enhancements in soil properties. The results indicated that total additional employment generated by shelterbelt technology was 106.4%, of this 76.5% employment was generated by shelterbelt alone and remaining 29.9% by complementary inputs.
Gajja et al., (2014) in another study indicated that total additional employment generated by adoption of shelterbelt technology was 106.4%, of which 76.5% employment was generated by shelterbelt alone and remaining 29.9% by complementary inputs.
Future directions and research opportunities
Despite the progress, several avenues for future research remain
Long-term Impact Studies
There is a need for long-term studies assessing the ecological and economic impacts of windbreaks and shelterbelts, particularly their effects on soil health and crop resilience over time. Studies on greenhouse gases mitigation, carbon sequestration, resource utilization and above- and below- ground interactions between the different components can be focused on. Lond term effects of the shelterbelt on biodiversity in the region are also to be monitored, especially the effect on pollinators. Research should also focus on the economic valuation of ecosystem services provided by these structures.
Integration with modern technologies
Utilizing remote sensing and GIS tools can enhance the design and monitoring of windbreaks, allowing for more precise management and assessment of their effectiveness.
Community involvement and knowledge transfer
Engaging local communities in research and implementation can facilitate knowledge transfer and ensure that practices are culturally appropriate and economically viable. Developing supportive policy frameworks that incentivize the adoption of windbreaks and shelterbelts is crucial for promoting these practices at a larger scale.
