eChapters

Introduction

Forest cover of India has been estimated to be 7,01,673 km2 (70.17 million ha) which is 21.34 per cent of the total geographical area of the country. The tree cover of the country is estimated to be 92,572 km2 which is 2.82 per cent of geographical area. The total forest and tree cover is 7,94,245 km2 which is 24.16 per cent of the total geographical area of the country. Out of this, 9.14per cent forest cover is in the form of open forests and another 1.26 per cent is scrub forests (FSI 2015). According to National Forest Policy 1988, one-third (33.33%) of the land area should be under the forest cover for sound ecological balance. It means that we have to bring another 11.66 % area under forest cover and at the same time improve quality of the degraded forests. However the horizontal expansion of land under tree cover is not possible. In order to increase the tree cover and fulfill the requirements of the people and industries,

Introduction

The literatures and researcher data showed that there is negative impacts of agricultural expansion, landscape modification and deforestation on biodiversity, ecosystem services, alteringthe species composition and their ecological functions (Tscharntke et al. 2005; Priess et al. 2007; Flynn et al. 2009; Senior et al. 2013; Deguines et al. 2014; Kumar 2016) which can lead to considerable changes in critical ecosystem processes. On the other hand, an increasingly industrialized global economy, rapid population growth, land degradation, land use pattern and role of various human activities have led to dramatically increased the pressure on the natural resources such as the available land for sustaining the livelihoods, and with over exploitation and extraction of the natural resources the ecosystems are becoming unsustainable and fragile since last century (Kumar 2017). Standardization of cultural practices is one of the primary objectives to make the system ecologically, sustainable and economically viable (Gill et al.2009).

Introduction

Agroforestry is a land-use management system where trees or shrubs are grown around or among crops or in pasture lands. It combines agricultural and forestry technologies to create more diverse, productive, profitable, healthy, and sustainable land use systems.
India has been at the forefront of agroforestry research ever since organized research in this area started worldwide about 25 years ago. Considering the country’s unique land use, demographic, political and socio-cultural characteristics as well as its strong contributions to agricultural and forestry research, India’s experience in agroforestry research has proved important to agroforestry development especially in developing countries.

Introduction

There is a growing interest in the role of different types of land use systems in stabilizing the atmospheric CO₂ concentration and reducing the CO₂ emissions or on increasing the carbon sink of forestry and agroforestry systems. Forestry has been recognized as a means to reduce CO₂ emissions as well as enhancing carbon sinks. There is considerable interest to increase the carbon storage capacity of terrestrial vegetation through land-use practices such as afforestation, reforestation, and natural regeneration of forests, silvicultural systems and agroforestry (Brown 1996; Canadell and Raupach 2008). Agroforestry systems are very important given the area currently under agriculture, the number of people who depend on land for their livelihoods, and the need for integrating food production with environmental services (Garrity 2004; Makundi and Sathaye 2004).

Introduction

Trees play an important role in ecosystem in all terrestrials and provide a range of products and services to rural and urban people (Gogoi 2015). As natural vegetation is cut for agriculture and other types of development, the benefits that trees provide are best sustained by integrating trees into agricultural system - a practice known as agroforestry. Agroforestry focuses on the wide range of trees grown on farms and other rural areas. Among these are fertilizer trees for land regeneration, soil health and food security; fruit trees for nutrition; fodder trees for livestock; timber and energy trees for shelter and fuel wood; medicinal trees to cure diseases and trees for minor products viz. gums, resins or latex products. Many of these trees are multipurpose, providing a range of benefits. Although effective and valuable tools have been introduced to evaluate the risk to construction in areas prone to geo-hydrological hazards, fewer steps have been made in the field of ordinary land use planning at different scales. 

Introduction

The world demand for wood is continuously increasing due to increase in population. The ever increasing population has led to depletion of existing timber reserves and the forestland base has been reduced by increased allocation of forest areas to urban, agricultural, recreational and other uses. The growing awareness towards development of plantations has generated a voluminous increase in the demand for quality planting material. Conventionally, propagation is achieved through sexual (seeds) or vegetative methods (rooting of cutting, grafting, layering, etc). Propagation through seeds is routinely used for production of planting material but it generates immense genetic variability which is not desirable while propagating perennial tree species. In order to propagate selected trees with desirable features vegetative propagation methods like rooting of cuttings, grafting, layering etc have been developed. These methods can produce genetically identical off springs thereby preserving the advantageous traits;

Introduction

Desertification is affecting the livelihoods of millions of people, mainly poor in the dry lands, which occupy nearly 41% of the Earth’s land area and are the residence of more than 2 billion people of the world. In India, the western part of Rajasthan is mostly affected by desertification process dominated by wind erosion. Kar et al. (2009) reported that 15.2 mha land in western Rajasthan is affected by wind erosion out of total 22.96 mha area under desertification. A brief account on issues and priorities related to wind erosion processes in Thar desert was reported in Santra et al. (2006). Plenty of incident solar energy in the region makes the desert surface very hot especially during summer months. Wind speed also remains very high in the region for most of the time in a year. Therefore, the loss of top fertile soils through wind erosion process is very active in the region. Eroded dust particles during severe wind erosion events commonly known as dust storms not only create the soils poor but also pose several environmental threats through generating aerosols in atmosphere. 

Introduction

The area under salt-affected soils in India is estimated to be 6.73 Mha spread over a number of states across the country. This 6.73 million ha are lying barren or produce very uneconomical yields of crops due to excessive accumulation of salts. These soils are agriculturally unproductive because of the high content of soluble salts which had harmful effects on plant growth due to moisture stress and toxicity/deficiency of some of the ions and the exchangeable sodium ions in clay complex lead to the unfavorable physical conditions of for the plant growth and water movement (Bhumla 1977). Saline and sodic soils have excess concentration of either soluble or exchangeable sodium, calcium and magnesium primarily in the form of chlorides and sulphates. Salt affected areas an expected to increase with spread of waterlogging and salinity due to increase in canal irrigation, and intensive exploitation of poor quality ground waters for agriculture in non canal commands. Certain states like Rajasthan and Haryana located in the western part of the country are endowed with 84 and 62% of poor quality ground waters, respectively. Continuous use of such waters for irrigation to agricultural crops is bound to increase the problem of salinity and sodicity in India (Yadav 1989; Minhas and Bajwa 2001). Introduction of irrigation without making proper provision for drainage is the major cause for the development of salinity in canal commands.It is severe on irrigated lands of the dry zone. It reduces crop yield and in severe cases causes complete abandonment of agriculture (Joshi and Dhir 1989; Joshi et al. 2000; Mahesh Kumar et al. 2016). The present paper deals with extent, causes, characteristics and management options of these soils for sustainability of agriculture in the area.

Introduction

A number of researchers have used morphological descriptors such as growth habit, leaf, shoot, flower, fruit morphology to classify and discriminate different varieties/cultivars and or detect inter and intra-specific variations in different tree species of economic importance (Saran et al. 2006; Holland et al. 2009). Such morphological descriptors are quite homogenous and often found insufficient to distinguish varieties within morphological groups. The choice of suitable cultivars is of paramount importance for its success. The lack of breakthrough has been due to under utilization of genetic variability for superior quality and high yield potential. Most of the fruit tree species demonstrates a rich genetic diversity mainly through natural cross pollination due to self incompatibility (Godara 1980). The elite plant types with desirable traits have been released as varieties, mass multiplied and propagated through standard vegetative multiplication. However, the authenticity of cultivar identification remains unclear (Devanshi et al. 2007).

Introduction

Rain fed agroecosystem occupies 68% of India’s cultivated area and supports 40% of the human beings and 65% of the livestock population. It produces 44% of food requirements, thus has and will continue to play a critical role in India’s agriculture (Singh et al. 2004). Besides their well established role in agriculture, livestock have crucial role in food security and as risk aversion mechanism for sustaining family, whenever there is crop failure. Indian hot arid zone which is about 12% of total geographical area of the landmass of 0.32 million km2 has maximum covering in western Rajasthan i.e. 61% of the total area whereas the other areas in arid region are available in the states of Gujarat, Punjab, Haryana, Andhra Pradesh and Karnataka accounting for 20, 5, 4, 7 and 3% of hot arid area whereas the cold arid area of 8.4 million ha lies in the state of Jammu & Kashmir covering the Leh and Ladakh region.

Introduction

Throughout the arid zones, there is no dearth of problems, but rapidly increasing desertification (some call it land degradation) is a problem of worldwide dimension. Water is a scare commodity in arid zones. Much of rainfall is lost by evapo-transpiration and as a result, ground water recharged only by seepage through soil profile. However, it is a common phenomenon in arid zones of the world that ground water is frequently used at the rate that exceeds recharge. The situation in arid tropics of India, which is spread over an area of 31.7 million ha, is no more different. Considering the role of agriculture in the social and economic progress of developing countries, the vulnerability of agricultural systems to the impacts of climate change has received considerable attention from the scientific community (Fischer et al. 2002; IISD 2003; Kurukulasuriya and Rosenthal 2003). Much of the available literature suggests that the overall impacts of climate change on agriculture especially in the tropics will be highly negative, although in a few areas there may be minor increases in crop yields in the short term (Maddison et al. 2007). Research on agroforestry as an adaptation to climate change and as a buffer against climate variability is in the process of evolving.

Introduction

Human civilization used to undergo several form of disasters throughout its life history. Most of such events are unpredictable, sudden and short in duration, and such events can easily classifiable as either natural (e.g. cyclones, earth quake, natural forest fires and tsunami) or manmade such as spread of toxic chemicals (e.g. Bhopal disaster 1984), nuclear explosions, civil war, diseases (Minamata, itaiitai, etc.). However, climate change is a real time prolonged disaster which is caused by both natural (caused by variation in solar irradiance, variations in orbital parameters of earth, volcanic activities, natural forest fire, methane release from thawing of permafrost from ocean floor, natural wetlands and cattle) and anthropogenic means (by greenhouse gases resulted from human activities-all kinds of combustion, industrial production of greenhouse gases and agricultural water lodging activities such as paddy cultivation and artificial wet lands, and deforestation).

Introduction

Two types of interactions, i.e. competitive and complementary, are found in ecosystems and agroecosystems (Callaway 1998), which shape community structure, plant diversity and system’s functions (Callaway 1995; Pugnaire et al. 1996; Bruno et al. 2003). Competitive interaction in ecosystems (Wedin and Tilman 1993) and agro-ecosystems (Pandey et al. 1999) is well documented. Mechanism of complementary interaction, however, is not much understood so far. Some studies (Bertness and Callaway 1994; Callaway 1998) argue that complementary interaction is facilitative, either facultative or obligatory, and occur generally in harsh physical environments. This suggests that habitat amelioration by neighbours is a common denominator of positive interactions (Bertness and Callaway 1994; Callaway and Walker 1997). Other studies report that complementary interaction is mutualistic (Boucher et al. 1982). Irrespective of whether facultative or mutualistic, it is now well established that complementary interaction is evolutionary (Bertness and Callaway 1994). But, it is still inconclusive how two species exist together in ecosystems and agroecosystems (Bertness and Callaway 1994).

Introduction

India has a long tradition of agroforestry which is widely practiced in all ecological and geographical regions of the country. Traditional agroforestry systems are broadly based on indigenous knowledge and the species are selected as a part of the cultural patterns of the community. The farmers and land owners in different parts of the country integrate a variety of woody perennials in the crop and livestock production systems depending upon the agro-climatic conditions and local requirements.

Introduction

Arid lands are among the world’s most fragile ecosystems, made more so by periodic droughts and increasing over exploitation of meagre resources. Arid and semi-arid lands cover around one-third of the world’s land area and are inhabited by about one billion people, a large proportion of whom are among the poorest in the world (Malagnoux et al. 2007). Arid environments are extremely diverse in terms of their land forms, soils, fauna, flora, water, and human activities. Aridity is usually expressed as ratio of mean annual precipitation (P) to the mean annual potential evapotranspiration (EPT) where potential evapotranspiration is calculated by method of Penman, taking into account atmospheric humidity, solar radiation, and wind speed. UNEP (1997) has recognized four main classes of aridity: hyper-arid (P/EPT < 0.03), arid (0.03 < P/EPT < 0.20), semi-arid (0.20 < P/EPT < 0.50), and dry sub-humid (0.50 < P/EPT < 0.65). Of the total land area of the world, the hyper-arid zone covers 4.2 %, the arid zone 14.6 %, and the semi-arid zone 12.2 % (FAO 1989). Therefore, almost one-third of the total area of the world is “arid land”. 

Introduction

Agriculture has always been vulnerable to fragile environmental conditions of dry areas, where droughts of varying amplitude and frequency influenced by insufficient and uncertain rainfall are common features. Recent anthropogenic activities have accelerated the rate of green house gas (GHGs) accumulation in atmosphere influencing atmospheric temperature and local patterns of temperature and precipitation, which ultimately affect agricultural production and food securities. About 35.5 percent of the total world’s population resides in dry areas, which is facing the problems of land degradation and food securities.

Introduction

Livestock sector plays an important role in the rural economy at national level and this sector is emerging as a driving force in agriculture by contributing towards the income and employment of rural households. Livestock contributed 16% to the income of small farm households that indicates importance of livestock sector as a whole. In 2010-11, livestock generated outputs worth Rs 2075 billion (at 2004-05 prices). Agriculture sector grew at low rate of 4.7% during 2013-14 and contributed 13.9% to National GDP (Economic Survey 2013-14). The livestock sector contributed over 4.1 per cent of the total GDP in 2012-13, that nearly accounts for 29.5% of the agricultural GDP (Economic Survey 2013-14) indicating a significant contribution of the livestock. Sheep and goats are an important livestock species for a large number of rural poor, especially socially backward, marginal and landless labourers in India. Sheep are mostly reared for wool and meat purpose. India ranks third in sheep population and account for nearly 6% of world sheep population, currently India has 65.06 million sheep as per Livestock census 2012.

Introduction

Arid regions of the world are diverse in terms of climate, soils, vegetation, animals and life style and activities of people. The binding feature of all arid regions in the world is aridity. Of the total area of arid zones of the world, Africa, accounts for 46.1 % followed by Asia (35.5 %). Majority of rest 19.4 % of arid zones are spread over in Australia, North America (Mexico and Southern part of USA), and South America. The Indian arid zone covers around 12 % of country’s geographical area occupying 31.8 million ha of land of which major part is in northwestern India (28.57 Mha) and some in southern India (3.13 Mha). It covers parts of Andhra Pradesh, Gujarat, Haryana, Karnataka, Maharashtra, Punjab and Rajasthan states of India (Table 1 and Fig. 1). The arid regions of Rajasthan, Gujarat, Punjab, and Haryana together constitute Great Indian Desert, better known as Thar. As arid western Rajasthan accounts for 61% of hot arid region of country, therefore it is considered principle hot arid region. Major part of it occurs between Aravalli ranges on the east and southeast and Thal desert of Pakistan (Thal desert is simply the western extension of Thar, only name has been changed) which is spread up to Suleman Kithara ranges in extreme west.

Introduction

Rainfall is the principal source of water in arid areas, which augments soil moisture, groundwater and surface flows. Agriculture and several of the other economic activities in arid areas depend on rain. This region is devoid of any well defined perennial river system. Under such circumstances every drop of water becomes very precious. Of the total water use about 85% of water is used for irrigation and remaining 15% is used for drinking, industrial and other purposes. About 65% of irrigation water and 30-40% of drinking water is subjected to serious losses. Hence, increasing water use efficiency coupled with increasing availability of water through rainwater harvesting and management is of prime importance for sustainable development of arid areas. Rainwater harvesting, its conservation and efficient utilization can solve problem of water scarcity to the greater extend. Rainwater harvesting in small ponds (nadis), underground tanks (tankas), Khadins (Low lying areas) etc. is an age-old tradition in arid zone of Rajasthan. These traditional rainwater harvesting structures vary in design, shape and size. These traditional methods have undergone several changes for being more economical and efficient. Central Arid Zone Research Institute (CAZRI), Jodhpur since its inception in year 1959 is continuously working for development and refinement of water efficient techniques for crop production, individuals and for the communities for development in hot arid zone of India.

Introduction

Agroforestry system (AFS) is a form of sustainable land use that combines trees, shrubs, crops and livestock so as to increase and diversify farm and forest production along with conserving natural resources. Microorganisms play a crucial role in improving nutrient availability to plants, thereby decreasing the dependence on chemical fertilizers and achieve sustainable agriculture through agroforestry (Araujo et al. 2012). Arbuscular mycorrhizal (AM) fungi, plant growth-promoting rhizobacteria (PGPR), and the association of rhizobia with leguminous plants are symbiotic associations of high economic importance for increasing agricultural production. Yadav et al. (2010) studied soil biological properties under different tree based traditional agroforestry systems in a semi-arid region of Rajasthan, India and concluded that biological properties can be optimized in the soil under AFS. Many authors have reported that soil microbial biomass and microbial diversity are greater in the AFS due to the ameliorative effects of trees and organic matter inputs and the differences in litter quality and quantity and root exudates (Mungai et al. 2005; Sørensen and Sessitsch, 2007). Also, the presence of a large and diverse soil microbial community is crucial to the productivity of any agroecosystem. Moreover, more than one plant species in AFS have been reported to have shown a larger diversity and/or abundance of mycorrhizal fungi than monocultures (Cardoso and Kuyper 2006) and more efficiency in biological fixation of the nitrogen, especially in tropical soils (Freitas et al. 2010). Also, soil microbial biomass has other important functions in the soil such as nutrient cycling and the degradation of pollutants (Watanabe and Hamamura 2003; Araújo and Monteiro 2006).

Introduction

Arid environs are delineated by extreme and harsh weather conditions due to excessive heat and inadequate, variable precipitation; however, contrasts in climate occur. These climatic disparities are the result of temperature variation, distribution and season of rainfall and the degree of aridity. Moreover, high evapo-transpiration, periodic droughts, low organic matter levels, different associations of vegetative cover and soil enhances the problems of these regions. In general, hot arid climates have excessive heat and strong prevailing winds, unhampered by obstacles on the ground and as result aeolian erosion is common with frequent seasonal drought occurrence (Sharma and Tewari 2005). These climatic limitations make very difficult place for the inhabitants to attain their livelihood. People of these areas have spent their life within these constraints for centuries. They have faced serious challenges due to lack of sufficient resources and very low productivity which has added to the vulnerability of the region. 

Effect on SOC and N losses through runoff and soil erosion

With increase in population, agriculture is being extended to even marginal soils which were hitherto uncultivated. Such soils are more seriously prone to erosion losses (FAO 2008), mostly because of their topographical position. Overall, soil organic matter and nutrient rich surface soil erosion could become more serious threat in the wake of changing climate in future; therefore, it is necessary to find suitable remedy measures to sustainable food production while protecting the soil from erosion.

Introduction

The rate of increase in anthropogenic CO₂ concentration of the atmosphere is increasing at an alarming rate from 1.7 µmol mol-1 yr-1 in 2009 (Tans 2009) to 2.2 µmol mol-1 yr-1 in 2013 (WMO 2013). At this rate, its level in the atmosphere will reach around 450 µmol mol-1 by the turn of century from its current concentration of 400 µmol mol-1, leading to increased global warming and concomitant climate change. There is, thus, a very strong scientific interest in finding ways to slow or reverse this trend. Mitigation strategy of diverting CO₂ from atmosphere to soil by adopting appropriate agricultural practices such as conservation agriculture (CA) is a recognized such method (Lal 2008 a, b). Broadly, CA has three major components- reduced tillage, crop residue management, and intensive cropping. Conservation tillage practices which include reduced tillage (RT) and no-tillage (NT) have been amply demonstrated as the agricultural practices that are very helpful in this direction (West and Post 2002; Franzluebbers 2010).

Introduction

Tree growing in hot arid region is basically concerned with the management of trees for conservation and for limited production objectives like wood for fuel, poles and fencing material; leaves for livestock fodder; and pod/seeds for many types use in human diet. The role of trees to conserve the fragile ecosystems of hot arid regions has been well recognized (Mann and Muthana 1984). The trees also provided so many services to mankind, which make them an intricate part of man-livestock-agriculture continuum, the lifeline of hot arid regions (Saxena 1997). 

Introduction

The green revolution in mid-sixties stirred by research based new technological developments involving new materials, models and ways of organizing farm inputs (water, fertilizer, chemical etc) and government’s policies transformed the agriculture dramatically. The outcome chewed a many fold increase in production and productivity viz. food grain production of 211 million tonnes (which was only 74.23 million tonnes in 1966-67) and food grain productivity of 1697 kg ha-1 (which was only 644 kg ha-1 in 1966-67). The country thus became self-sufficient in food production despite tremendous pressure to sustain 16% of world human population and 10% of cattle population with just 2.4% of total land.

Introduction

India is the seventh-largest country in the world, with a total area of 3,287,263 square kilometres, roughly 2.5 percent of global landmass but is home to 17.9 percent of global human population and 1/5 of the livestock. Most of this increase in human population has occurred in second half of 20th century. Similarly, India has the highest number of cattle (210.2 m), buffaloes (111.3 m) and goats (150.4 m) in the world. It ranks second in sheep (74 m), fifth in chickens (866 m) and sixth in ducks (26 m). The increased population and associated increased demand of resources has led to significant impact on land use-land cover and has consequence in negatively impacting various ecosystem services i.e., hydrology, soil conservation, wildlife support, biodiversity and environmental protection, these agroforestry systems used to provide. Agroforestry has traditionally been a way of life and livelihood in India for centuries. Now it is a modern science inviting deliberate management of trees on farms and surrounding landscape (Bargali et al. 2009; 

Introduction

Agroforestry is the science of designing and developing integrated self-sustainable land management system, which involves introduction or retention of woody components such as trees, shrubs along with agricultural crops including pasture/animals simultaneously or sequentially, on the same unit of land and at the same time, to meet the ecological as well as socio-economic needs of local people. A typical agroforestry system will allow economic and ecological interactions between woody and non-woody components and also increase, sustain and diversify the total land output. Agroforestry systems are very important for the area currently under agriculture, the number of people who depend on land for their livelihoods, and the need for integrating food production with environmental services (Garrity, 2004; Makundi and Sathaye 2004). Agroforestry provides a unique opportunity to combine the twin objectives of climate change adaptation and mitigation. Although agroforestry systems are not primarily designed for carbon sequestration, there are many recent studies that substantiate the evidence that agroforestry systems can play a majorrole in storing carbon in above ground biomass (Sathaye et al. 2001;

Introduction

Agroforestry, the word coined in the early seventies, has made its place in all the developed and the developing countries of the world and is now recognized as an important approach to ensuring food security and rebuilding resilient rural environments (Luedeling et al. 2014).  Agroforestry applies to private agricultural and forest lands and communities that also include highly erodible, flood-prone, economically marginal and environmentally sensitive lands (Continents 1986). The typical situation is agricultural, where trees are added to create desired benefits. Agroforestry allows for the diversification of farm activities and makes better use of environmental resources (Taylor et al. 2007). Agroforestry is defined as a land use system which integrates trees and shrubs on farmlands and rural landscapes to enhance productivity, profitability, diversity and ecosystem sustainability. It is a dynamic, ecologically based, natural resource management system that, through the integration of woody perennials on farms and in the agricultural landscape, diversifies and sustains production and builds social institutions. India has been an all-time leader in agroforestry (Chavan et al. 2015).

Introduction

Low and erratic rainfall, extreme temperatures, long sunshine duration, high wind velocity, high evapotranspiration, low fertility of soil and paucity of water resources characterize hot arid region of India. Despite these hostile conditions, the region supports a large number of human and livestock population. However, the ever increasing human and livestock population and developmental activities exerts enormous pressure on natural resources and posing serious threat to sustainability of the region. In these hostile environmental conditions, several indigenous agroforestry systems are being practiced by farmers of this region (Shankarnarayanan et al. 1987). The agroforestry, which is a dynamic, ecologically based natural resource management practices that, through the integration of trees and other tall woody plants on farms and in the agricultural landscape, diversify production for increased social, economic and environmental benefits (ICRAF 2000). A number of studies have recognized the multiple benefits of agroforestry that include carbon sequestration, reducing forest degradation, biomass production, food security, income diversification, improvement and maintenance of soil biodiversity, provision of wildlife corridors, and a host of other ecological services and social benefits. In the last three decades, agroforestry has been widely promoted in the tropics as a natural resource management strategy that attempts to balance the goals of agricultural development with the conservation of soils, water, local and regional climate

Introduction

It is well known that, over 50% of requirement of food for the entire humanity is obtained from just three crops- rice, maize and wheat though 150 crops are commercialized globally. Ethnobotanically, over 7000 plants species are cultivated or harvested from the wild which represent immense agro-biodiversity. Most of these species are under exploited but have the potential for contributing to food security, health (nutritional/medicinal), income generation and environmental services. Examples include little millets which provide calcium and iron and vitamins like niacin and sulphur containing amino acids, having more fiber than rice and wheat. Some other species which have in the recent past contributed to income generation in Indian arid zone include ber, anola, karonda and gonda. Likewise the perennial grasses in this area are not only source of nutritious fodder but also the grains e.g. gramana (Panicum antidotale) are consumed during famine. They have acquired importance being alternative sources of income as also alternate life support system during crisis. They often have neutraceutical, medicinal uses or often multiple uses. Demand for traditional food in large multi-ethnic cities and metros have brought these species into sharp focus, Hence, these are being viewed now as potential candidate for diversification in the cropping system, conservation of bio-diversity, enhancing the limits of green revolution even during climate change and finally as provider of molecules for curing various ailments of men and animals.

Introduction

Agroforestry is the intentional combination of agriculture and forestry technologies to create integrated, diverse, productive, profitable, and sustainable land-use systems (Rietveld 1995). It creates complex systems with impacts ranging from the site or practice level up to the landscape and beyond (Ellis, 2004). It is one of the most conspicuous land use systems that consists of annual and perennial plants, which are often integrated with livestock. It provides ecosystem services and reduces anthropological impacts on natural forests, arrests soil degradation, enhance soil fertility in many situations and improve farm resilience (Thangataa and Hildebrand 2012; Tewari et al. 2013). Agroforestry is a land management and farming system that are not only capable of fulfilling household needs but also maintaining and improving environmental quality. Itplays a vital role in achieving integrated rural and urban development. The changing climate has potential impacts on ecosystem goods and services by means of increased variability with greater risk of extreme weather events, such as prolonged drought, storms and floods (Lindner et al. 2010). Agroecosystem and forests are the ecosystems which are the most adversely affected by climate change by means of prevalence of pests, diseases, invasive species, species endangerment and high levels of food insecurity.

Introduction

Globally, now scholars accepted that the climate is changing and it has implications on human culture, social systems, economic stress and ecological problems (Ford et al. 2010). The IPCC advocates to search and develop local solutions for climate change adaptations (IPCC 1996; IPCC, 2001), however, it does not recognize the breadth and strength of centuries-tested community knowledge/traditional knowledge systems (Salick et al. 2009) which are available with the people of developing world, and has been for adaptation practices and strategies to extreme weather and climate change (Turner and Clifton 2009; Salick and Ross 2009). It is well recognized that with fragile ecosystems, poor economic status and with less robust technologies required to adapt climate change, marginal and poor people of developing countries are likely to be more vulnerable with the changing climate than the industrialized countries (Tompkin and Adger 2004; Agrawal, 2008).

Introduction

The major environmental issue of global nature is increasing green house effect, which is warming earth. Enhanced green house effect is mainly due to increased emission of carbon dioxide, methane, nitrous oxide and CFCs. Because of the increasing concentrations of these greenhouse gases, there is much concern about future changes in our climate and direct or indirect effect on agriculture (Arora et al. 2011). Increases in atmospheric concentrations of green house gases and additional anthropogenic perturbations of the climate system affect the spatial and temporal distribution of weather regimes which contribute to shaping the diversity of agricultural activities throughout the world (Havlik et al. 2015). Consequences of changing climatic attributes such as rainfall, moisture regimes, temperature etc. affect qualitative and quantitative production of agricultural crops as well as livestock population by altering pasture quality and yield (Thornton et al. 2009). In the context of climate change mitigation, now a days adoption of climate smart agriculture work as an effective practice.

Key facts

Freshwater biotoxins

    
•    Biotoxins are naturally occurring toxic compounds produced by some freshwater cyanobacteria (blue-green algae) and marine algal species (dinoflagellates, diatoms).
    
•    Cyanobacteria are now recognised as a serious water quality problem with regard to drinking water supply and recreational use.
    
•    Environmental conditions that can promote cyanobacterial/blue-green algal blooms are: excessive nutrients (phosphorus and nitrogen); warm water temperatures (15-30OC); sunlight for photosynthesis; and quiescent or stagnant water.
    
•    Outbreak of human poisoning attributed to cyanobacteria are neurotoxins (e.g. anatoxin-a, anatoxin-a(s), saxitoxins) and hepatotoxins (e.g. microcystins, nodularin) produced by some strains of the cyanobacteria including Microcystis, Anabaena, Aphanizomenon spp.

Key facts
    
•    Biotoxins are naturally occurring toxic compounds produced by some freshwater cyanobacteria (blue-green algae) and marine algal species (dinoflagellates, diatoms).
    
•    Tonnes of pharmacologically active substances are used annually in human and veterinary medicines, some of these substances are excreted (human and animal) non-metabolised or an active metabolites and enter into the environment since waste water treatment plant (WWTP) cannot degrade them.
    
•    In Europe, around 4,000 different pharmaceutically active compounds are used as human and veterinary drugs and the annual consumption is about several hundred tonnes.
    
•    European Union and the United States laws require an assessment of potential risks to the environment as part of license application processes for new medicinal products.

•    Pharmaceutical products are generally polar, water soluble and low volatile molecules, it means that they have high mobility in the environment.

Key facts

    
•    Endocrine disrupting chemicals (EDCs) are micropollutants with estrogenic or androgenic activities at very low concentrations and are emerging as a major concern for water quality.
    
•    EDCs include natural and synthetic hormones (Estrone or E1, 17b-estradiol or E2, Estriol or E3, 17a-ethynylestradiol or EE2); alkylphenols (nonylphenol or NP; octyphenol or OP), phenols (bisphenol-A or BPA), phthalates (Di-n-butyl phthalate or DBP, Di-2-(ethylhexyl)-phthalate or DEHP); organotins (tributyltin or TBT); and phytoestrogens (b-sitosterol, coumestrols, genistein). 
    
•    Wastewater treatment plants, intensive livestock effluents, industrial wastewaters, landfill, paper and pulp mill effluents and antifouling paints are important sources of EDCs in the environment.

Key facts
    
•    Dioxins are the most dangerous and ‘super toxic’ chemicals so far known on the earth and three closely related families are collectively known as dioxins. These are Polychlorinated dibenzo-p-dioxin or dioxins (PCDDs), Polychlorinated dibenzofurans or furans (PCDFs) and polychlorinated biphenyls (PCBs).
    
•    2, 3, 7, 8-TCDD (or called TCDD) is the most potent of all the congeners. The toxicity equivalency factor or TEF of TCDD has been assigned as 1, while all other congeners assigned in order of toxicity ranking magnitude relative to TCDD.
    
•    There are 75 compounds/congeners in the dioxin family (PCDD), 135 compounds in the furan family (PCDF) and 209 possible compounds in the PCBs based on the possible number of chlorine atoms.
    
•    The toxicity of dioxins and dioxin-like compounds vary substantially among the different PCDDs, PCDFs and PCBs. It is generally accepted that only 29 out of the 419 congeners of dibenzo-p-dioxins, dibenzofurans and polychlorinated biphenyls are toxic to humans and other organisms. The TCDD is most toxic and registered by the WHO as carcinogenic for humans.

Key facts
    
•    Pesticides are chemicals that are broadly used to protect crops, livestock and other animals and plants from pests and diseases. They are classified according to the type of pest to be controlled (algicides, herbicides, fungicides and insecticides).
    
•    Commercial production of DDT began in 1943. At that time, DDT was considered to be a wonderful invention. It was cheap to produce, very toxic to insects and much less toxic to mammals and its usage resulted in a sharp decline of mosquito borne diseases. In 1962, it was discovered that DDT was causing egg-shell thinning in bird eggs and thus was leading to the near extinction of bird species such as peregrine falcons and bald eagles.
    
•    Pesticides use has greatly helped to increase and improve the world food production. Use of pesticides also increases farmer’s profits by preventing crop losses due to pest attacks and weed infestation.

Key Facts

    •    The heavy metals (HM) or trace metals in an aquatic environment can come from natural (e.g. geological minerals, wind blown silicate dust, volcanic emissions, sea spray and combustion) and anthropogenic sources (e.g. mining, industry and sewage treatment discharges as well as electronic waste and agriculture fertilisers). In aquatic systems, the heavy metals of greatest concerns are cadmium, copper, lead, mercury and zinc.
    •    Metals may exist in a number of physico-chemical states in aqueous systems such as particulate matter and dissolved forms. Metal speciation in freshwater is strongly influenced by hardness, alkalinity, pH, natural dissolved organic matter (DOM) and redox potential. 
    •    Water hardness is quantitatively related to metal toxicity in freshwater (i.e. toxicity of heavy metals decrease with increasing hardness and alkalinity; on the other hand, toxicity increases with decreasing salinity, dissolved organic matter and chelators). The uptake and toxicity of heavy metals of most metals in marine waters is low as compared to freshwater because metals are easily complexed with chloride ions.
    •    The toxicity of HMs is related to the dissolved ionic form of the metal rather than total concentration of the metal. Each different physico-chemical forms of an element has a different toxicity, for example, if the element (e.g. Cu) is absorbed on a colloidal particles it is expected to be of little or no effect on aquatic organisms, however,  if the copper is available as free Cu (II) ion, few aquatic organisms may survive.

Key facts

    
•    Arsenic (As) is a metalloid, with properties intermediate between those of a metal and a non-metal. Arsenic can exit in the environment and biological systems in various inorganic and organic forms (species). These are arsenite - AsIII, arsenate - AsV, monomethyl arsonic acid (MMAA), dimethyl arsinic acid (DMAA), arsenocholine, arsenobetaine and arsenosugars. 
    
•    Arsenicals have a wide range of toxicity. In general, inorganic arsenicals are more toxic than oragnoarsenicals to biota and trivalent arsenic (arsenite) is more acutely toxic than pentavalent (arsenate) form in the following orders:
    
    Arsenous acid (AsIII) ®  arsenic acid (AsV) ® MMAA ®DMAA ® arsenocholine ® arsenobetaine.
    
•    Under oxidizing and aerobic conditions, the predominant form of arsenic (As) in soil and water is arsenate (AsV), whereas under anaerobic and reducing/or waterlogged conditions, arsenite (AsIII) predominates.
    
•    Inorganic AsIII and AsV are the major As species in groundwater, soils, terrestrial plants, whereas the main species found in marine animals is Arsenobetaine (AsB), which is considered to be non-toxic.
    
•    The LD50 values of different arsenicals show that arsenite (AsIII) is most toxic (LD50 range 15-42 mg/kg) and arsenobetaine is least toxic (LD50 > 10,000 mg/kg).

Key facts

    
•    The use of chemicals has many benefits, however, there are potential risks that some of these chemicals may cause harm to organisms and human health if they enter into the environment.
    
•    Harmful chemicals are those chemicals which are persistent, bio-accumulative, as well as toxic (PBT). 
    
•    Environmental or ecological risk assessment (ERA) consists of hazard identification, effect assessment, exposure assessment, risk characterization, risk classification, risk-benefit analysis, risk reduction and monitoring.
    
•    The five types of environmental monitoring are: chemical monitoring, bio-accumulation monitoring, biological effect monitoring, health monitoring and ecosystem monitoring. 
    
•    An integrated monitoring program is a coordinated monitoring activity comprising of both chemical and biological measurements in a variety of environmental compartments. There are four different monitoring levels in an integrated ERA, these are: suborganismals (biomarkers), organisms (bioassays), populations (bio-indicators) and ecosystems (ecological indicators).

Key facts

    
•    The climate change is likely to affect millions of people both directly (via increased deaths, disease and injury from heatwaves, floods, storms, fires and droughts) and indirectly (through changes in the water, air, food quality and quantity and ranges of vectors, such as mosquitoes, water-borne pathogens).
    
•    Recent observed climate change related effects include: (a) an increase in heat related deaths across the globe (Australia, Canada, France, Germany, the Netherlands, Portugal, Switzerland, UK and USA; (b) spread of vector- and rodent-borne diseases such as malaria (Africa, India) and dengue and (c) increase in food poisoning (New Zealand).
    
•    Heatwaves can cause adverse health effects such as heat cramps, fainting, heat exhaustion and heat stroke. Human deaths due to heatwaves are associated with cardiovascular and respiratory diseases and in 2003 in Europe 70,000 deaths were recorded from heatwaves alone.
    
•    Projections : (a) cold temperature is expected to become less frequent, while heat waves will become more frequent; (b) increases in heat related deaths and illness across the globe including Australia, Germany, Portugal, UK, and USA;  (c) malaria zone may expand in Australia, Africa (highlands), India and  260-320 million more people will be affected by malaria by 2080;  (d) dengue area is likely to increase as climate would be more suitable and by 2085, about 6 billion people will be at risk of contracting dengue fever including Australia and New Zealand; (e) diarrhoeal disease may increase with temperature increase; and (f) cholera outbreaks may rise as a result of more plankton blooms providing nutrients for Vibrio cholerae.

Key facts

    
•    Fish is an important source of animal protein for billions of people (estimate 2.6 billion people). About 200 million people and their dependants worldwide, mostly in developing countries, live by fishing and aquaculture. 
    
•    Fish living in temperate and Polar Regions could be benefited from climate changes since an increase in water temperature would extend the fish growing season. Moreover, rising temperature could reduce over-wintering stress normally experienced by temperate fishes.
    
•    Rise of temperature may cause a decrease in dissolved oxygen (DO) or hypoxic conditions (as temperature and DO are inversely related) and can impair fish reproduction and may cause endocrine disruption in fish (increase incidence of malformations and may alter sex differentiation and sex determination in fish).
    
•    Bioavailability and toxicity of common pollutants such as pesticides and heavy metals may be enhanced with increasing temperatures. Therefore, exposure of toxicants at elevated temperatures may cause a decline in recreational and commercial fisheries.

Key facts

    
•    Agriculture is the major land use across the globe. Agriculture production (plant growth) is highly dependent on climate since crop growth is influenced by solar radiation, temperature and precipitation. Agriculture is also sensitive to climate variability and weather extremes (droughts, floods, severe storms).
    
•    The yields of C₃ crops (rice, wheat, and soybean) is expected to increase (10-20%) with predicted doubling of CO₂ concentrations compared to C₄ crops (maize, sorghum, millet, sugarcane) since C₃ plants respond readily/positively to increased CO₂ levels. Therefore, CO₂ enrichment may benefit temperate and humid tropical agriculture compared to semi-arid tropics.
    
•    The predicted rise of temperature could impact crop and horticulture yield if it exceeds optimal temperature range. For example, low latitudes crops are being grown near the limits of temperature tolerance and global warming may put them to higher stress.
    
•    On a world wide basis, global warming would benefit the mid to high latitude zones for agriculture (for a small change of temperature of 1-3^ºC), whereas low latitudes, semi-arid and tropical areas will have much reduced crop and livestock yields. However, adaptation measures may reduce such impacts.

Key facts

    
•    Though water is the most widely occurring substance on earth, freshwater accounts for only 2.5% whereas the rest of water is saltwater. The agriculture sector uses more than 75% of freshwater available. 
    
•    The current observed climate change impacts on water resources include increased precipitation at high latitudes and temperate areas, decreasing precipitation at low latitudes; decreasing snow covers, and glaciers in most regions; decreasing flows in some river basins; floods and droughts in some countries and significant decreases in lake and river size in Africa.
    
•    A number of climate models projected that a doubling of atmospheric concentrations of CO₂ would increase global precipitation by at least 5%.  The precipitation is expected to increase in some areas, such as, at high latitudes and in the tropics (south east monsoon regions and over the tropical Pacific), whereas the precipitation is likely to decrease in the sub-tropics (e.g. much of North Africa and northern Sahara).

Key Facts
    
•    The United Nations Framework Convention on Climate Change (UNFCCC) defines ‘climate change’ as a ‘Change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods’.
    
•    The main green house gases (GHG) that have caused the global climate change or global warming are carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (NO₂).
    
•    CO₂ is the principal anthropogenic greenhouse gas that affects the Earths radiative balance. It is the reference gas against which other GHGs are measured and therefore has a Global Warming Potential (GWP) of 1. CH₄ and N₂O have a GWP of 21 and 310 respectively.
    
•    CO₂ is responsible for most of the enhanced green house effect of more than 50%, CH4 about 10 to 15% and NO2 about 4%.
    
•    The global atmospheric concentrations of carbon-dioxide, methane and nitrous oxide have increased since 1750, CO₂ increased from a pre-industrial value of 280 ppm to 379 ppm in 2005, CH₄ increased from 715 ppb to 1774 ppb and NO₂ increased from 270 ppb to 319 ppb in 2005.

Key facts
        
Agriculture and livestock
    
·    The Intergovernmental Panel on Climate Change (IPCC) defines adaptation as ‘adjustment in natural or human systems in response to actual or expected climatic stimuli or their effects, which moderates harm or exploits beneficial opportunities’. The adaptation can be considered as tackling the effects of climate change, whereas mitigation is tackling the cause of climate change such as reducing the sources or enhancing the sinks of greenhouse gases. There could be different types of adaptation such as autonomous (spontaneous) and planned adaptation (policy decision).
    
·    Autonomous adaptation includes altering varieties and/or species those are more appropriate to the altered thermal regime or with increased resistance to heat shock and drought; altering the timing or location of cropping activities; altering fertilizer rates to maintain grain or fruit quality consistent with the climate and altering amounts and timing of irrigation and other water management practices; diversifying income by integrating other farming activities such as livestock raising, integrated agriculture and aquaculture/fish farming; development and use of varieties and species resistant to pests and diseases, wider use of technologies to ‘harvest’ water, conserve soil moisture (e.g. crop residue retention) and to use water more effectively in areas where rainfall is projected to decrease and using seasonal climate forecasting to reduce production risk.

Key facts
    
·    The Food and Agriculture Organization (FAO) defines food security as a ’situation that exists when all people, at all times, have physical, social and economic access to sufficient, safe and nutritious food that meets their dietary needs and food preferences for an active and healthy life’. There are four dimensions of food security: Food Availability (availability of sufficient food for all people at all times, i.e. production); Food Accessibility (physical and economic access to food at all times, i.e. affordability), Food Utilization (access to food that is nutritious, safe and produced in environmentally sustainable ways, i.e. nutrients in food and food safety); and Food Stability (reliability of adequate food supply).
    
·    Agriculture is important for food security since it provides food for the people and is the primary source of livelihood for 36% of the world’s total workforce. In the heavily populated countries such as Asia and the Pacific, about 40% to 50%, and in sub-Saharan Africa, about two-thirds of the working population make their living from agriculture.
    
·    Agriculture, livestock and fisheries production are all sensitive to climate and are affected by its changes. Climate change will increase hunger and malnutrition, emergence of new pests and diseases and will threaten fishing and aquaculture industries.

Key Facts
        
Agricultural food
    
·    There are multiple pathways through which climate-related factors may impact food contamination and food safety, food quality, foodborne diseases including changes in temperature and precipitation patterns, increased frequency and intensity of extreme weather events, ocean warming and acidification and changes in the transport pathways of complex contaminants.
    
·    All or most foodborne pathogens and their associated diseases are linked to changing environmental conditions, the notable of which are campylobacteriosis, salmonellosis and vibriosis.
    
·    An estimated 30% of reported cases of salmonellosis across much of continental Europe have been attributed to warm temperatures, especially when they exceed a threshold of 6°C above average. Likewise both in Australia and Canada a positive correlation was found between increasing temperature and incidence of salmonellosis.
    
·    Zoonosis such as Rift Valley Fever (RVF), West Nile Fever, tick-borne diseases and non-zoonotic animal diseases such as Blue tongue, African horse sickness, African swine fever are examples of animal diseases whose distribution is expected to be strongly influenced by climate change and variability.
    
·    Mycotoxin is a toxic secondary metabolite produced by filamentous fungi, commonly known as moulds and may contaminate agricultural commodities (food) by growing on them both before and after harvest, whenever the humidity and temperature are permissive. The most prominent mycotoxins are aflatoxins, deoxynivalenol, zearalenone, ochratoxin-A, fumonisin, and patulin.
    
·    The humans ingestion of mycotoxins occur through consumption of the mycotoxin contaminated plant-based foods, such as grains, maize, barley, rice, coffee, nuts and their residues, and metabolites in animal-derived foods, for example aflatoxin M1 (AFM1) in milk and meat products. In addition, mycotoxins may occur in beer and wine.

Key facts

Agriculture
    
·    Agriculture production (plant growth) is highly dependent on climate since crop growth is influenced by solar radiation, temperature and precipitation and sensitive to climate variability and weather extremes (droughts, floods, severe storms).
    
·    Climate change is projected to have an effect on local agriculture and the net result could be harmful (e.g. frequent droughts, salinization of agriculture land due to sea level rise) or beneficial, (e.g. enhance CO₂ and higher yield, longer growing season, increased precipitation) or mixed.
    
·    Climate change or a doubling of GHGs (2 x CO₂) is projected to cause both gains and losses of agriculture land.
    
·    Each crop has a specific temperature range at which vegetative and reproductive growth will proceed at the optimal rate and exposures to extreme temperatures during these phases can impact growth and yield. Higher temperatures during the reproductive stage of development can affect pollen viability, fertilization and grain or fruit formation. 
    
·    Warming generally allow plants to grow faster that are below their optimum temperature, however for cereal crops faster growth means there is less time for the grain itself to grow and mature, reducing yields. 
    
·    Night-time temperatures are rising faster than daytime temperatures and are expected to continue rise in the future. According to International Rice Research Institute (IRRI), Philippines, the rise of night time temperature decreases rice yield by 10% for each 1°C increase in growing-season night time temperature in the dry season.