eChapters

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.