2017 Solved Old Paper (BOT-103)
Habitat (आवास):- It is a place or area where a species grows, lives or thrives. It is a natural environment where an animal utilizes the resources to find food to eat, shelter from heat and cold, and protection from predators and mates.
(यह वह स्थान या क्षेत्र है जहां कोई जाति बढ़ती है, रहती है या पनपती है। यह एक प्राकृतिक वातावरण है जहां एक जन्तु खाने के लिए भोजन, गर्मी व ठंड से आश्रय, शिकारियों व साथियों से सुरक्षा खोजने के लिए संसाधनों का उपयोग करता है।)
Continuous Change (सतत परिवर्तन):- Habitats might change over time either due to important environmental changes like -
(निम्न महत्वपूर्ण पर्यावरणीय परिवर्तनों के कारण समय के साथ आवास बदल सकते हैं -)
i. Volcanoes (ज्वालामुखी)
ii. Tornadoes (तूफ़ान)
iii. Changes in climate over a lengthy period
(लम्बी अवधि में जलवायु में परिवर्तन)
iv. Deforestation (वनों की कटाई)
v. Urbanization (शहरीकरण)
vi. Pollution (प्रदूषण)
vii. Availability of food and water
(भोजन और जल की उपलब्धता)
Types of Habitat (आवास के प्रकार):-
a. Terrestrial Habitats (स्थलीय आवास):- Habitats on land. Many types -
(भूमि पर आवास. कई प्रकार -)
i. Grassland (घास के मैदान):- Grassland habitats are dominated by grass, small trees and shrubs. They get moderate rain, usually windy and dry.
(घास के मैदानों में घास, छोटे पेड़ और झाड़ियाँ प्रमुख हैं। उनमें मध्यम वर्षा होती है, जो आमतौर पर हवादार और शुष्क होती है।)
ii. Mountains (पर्वत):- Mountains are habitats found at higher altitudes where the climate is extremely cold and windy.
(पर्वत उच्च ऊंचाई पर पाए जाने वाले आवास हैं जहां की जलवायु अत्यधिक ठंडी और तेज़ हवा वाली होती है।)
iii. Forests (वन):- Forest habitats are divided into three sub-division. They are Tropical forests, Temperate forests and Boreal forests. They are dominated by the presence of a large number of plants and trees.
(वन आवासों को तीन उपविभागों में विभाजित किया गया है। वे उष्णकटिबंधीय वन, शीतोष्ण वन और बोरियल वन हैं। इनमें बड़ी संख्या में पौधों और पेड़ों की उपस्थिति का प्रभुत्व है।)
iv. Deserts (रेगिस्तान):- Deserts are sandy lands that receive very little rainfall, and the regions are hot and dry.
(रेगिस्तान रेतीली भूमि हैं जिनमें बहुत कम वर्षा होती है, और क्षेत्र गर्म और शुष्क होते हैं।)
v. Polar regions (ध्रुवीय क्षेत्र):- Polar regions are totally covered with snow and can experience very cold temperatures.
(ध्रुवीय क्षेत्र पूरी तरह से बर्फ से ढके होते हैं और वहां बहुत ठंडे तापमान का अनुभव हो सकता है।)
b. Aquatic Habitats (जलीय आवास):- Habitats in water. 2 types-
(जल में आवास. 2 प्रकार-)
i. Freshwater Habitat (शुद्धजल आवास):- Freshwater habitat includes rivers, streams, ponds and lakes.
(मीठे जल के आवास में नदियाँ, झरने, तालाब और झीलें शामिल हैं।)
ii. Marine Habitat (समुंद्री आवास):- The saltwater habitat is called marine habitat. Planktons, seaweeds, fish, whales, crabs, octopuses, turtles, starfish, etc., are present in this habitat.
(खारे जल के आवास को समुद्री आवास कहा जाता है। इस आवास में प्लवक, समुद्री शैवाल, मछली, व्हेल, केकड़े, ऑक्टोपस, कछुए, तारामछली आदि मौजूद हैं।)
Niche (निच):- It is defined as a functional role played by an organism in its ecosystem. It is the effective role and position of a species in its environment that describes how the species responds to the location of resources and competitors or predators.
(इसे किसी जीव द्वारा उसके पारिस्थितिकी तंत्र में निभाई जाने वाली कार्यात्मक भूमिका के रूप में परिभाषित किया गया है। यह अपने पर्यावरण में किसी जाति की प्रभावी भूमिका और स्थिति है जो बताती है कि जाति संसाधनों और प्रतिस्पर्धियों या शिकारियों के स्थान पर कैसे प्रतिक्रिया करती है।)
> Joseph Grinnel coined the term “Niche”. He described a niche as the distributional unit specific to each species.
(जोसेफ़ ग्रिनेल ने "निच" शब्द दिया। उन्होंने प्रत्येक जाति के लिए विशिष्ट वितरण इकाई के रूप में एक निच का वर्णन किया।)
Characreristics of niche (निच के अभिलक्षण):-
i. Interactions (अंतरक्रियाएं):- A niche may also involve what that individual eats, how it interacts with other living things, and also how it connects with the non-living factors.
(एक निच में यह भी शामिल हो सकता है कि वह जीव क्या खाता है, वह अन्य जीवित चीजों के साथ कैसे संपर्क करता है, और यह भी कि वह निर्जीव कारकों से कैसे जुड़ता है।)
ii. Energy flow (ऊर्जा प्रवाह):- Niche consumes the flow of energy from one species to another, and thus it is very important to accept how a species eats or interacts with other organisms in an ecosystem to maintain ecological balance.
(निच एक जाति से दूसरी जाति में ऊर्जा के प्रवाह का उपभोग करता है, और इस प्रकार पारिस्थितिक संतुलन बनाए रखने के लिए यह स्वीकार करना बहुत महत्वपूर्ण है कि एक जाति पारिस्थितिक तंत्र में अन्य जीवों को कैसे खाती है या उनके साथ कैसे अंतरक्रिया करती है।)
iii. Balance (संतुलन):- Without ecological niches, there would be less biological variety, and the ecosystem would not be in balance. For example, a population in an environment make use of the resources and breeds to produce more animals or organisms, which then escalate the resources for the predators.
(पारिस्थितिक निचों के बिना, जैविक विविधता कम होगी, और पारिस्थितिकी तंत्र संतुलन में नहीं होगा। उदाहरण के लिए, किसी पर्यावरण में एक आबादी अधिक जंतुओं या जीवों को पैदा करने के लिए संसाधनों और नस्लों का उपयोग करती है, जो फिर शिकारियों के लिए संसाधनों को बढ़ाती है।)
iv. Factors (कारक):- The full span of biotic and abiotic factors utilized by species for duration form the fundamental niche, and the element that limits the population, like competition and predators, are called limiting factors.
(जाति द्वारा उपयोग किए जाने वाले जैविक और अजैविक कारकों की पूरी अवधि मौलिक निच बनाती है, और जो तत्व जनसंख्या को सीमित करते हैं, जैसे प्रतिस्पर्धा और शिकारियों को सीमित कारक कहा जाता है।)
Types of Niches (निच के प्रकार):- 5 types - (5 निच -)
i. Habitat Niche (Spatial Niche) आवास निच (स्थानिक निच):- It accounts for the physical space occupied by an organism. This explains the different microhabitats owned by several species having similar general habitats. E.g. seven species of millipedes reside in the same general habitat of the forest floor of a maple oak forest, and all are decomposers, i.e. occupy the same trophic level but predominate in their specific microhabitat that is created by several gradients in the decomposition stage.
(यह किसी जीव द्वारा घेरे गए भौतिक स्थान का वर्णन करता है। यह समान सामान्य आवास वाली कई जातियों के विभिन्न सूक्ष्म आवासों की व्याख्या करता है। जैसे मिलिपीड की 7 जातियाँ मेपल ओक वन के वन तल के एक ही सामान्य निवास स्थान में रहती हैं, और सभी अपघटक हैं, अर्थात एक ही पोषक स्तर पर रहते हैं लेकिन अपने विशिष्ट सूक्ष्म आवास में प्रबल होते हैं जो कि अपघटन चरण में कई प्रवणता द्वारा बनाया जाता है।)
ii. Trophic Niche (पोषक निच):- It tells about the functional role or trophic position occupied by a species. It explains how different species share the same habitat but occupy different trophic niches. E.g. Darwin’s finches of the Galapagos islands. These birds belong to the same genera and live in the same general habitat but differ in their eating habits, i.e. trophic position. One species is vegetarian, feeding on buds and fruits, and, others are insect eaters, feeding on insects of different sizes. There is a woodpecker finch, which has a wood-pecking beak.
(यह किसी जाति की कार्यात्मक भूमिका या पोषी स्थिति के बारे में बताता है। यह बताता है कि कैसे विभिन्न जातियाँ एक ही निवास स्थान साझा करती हैं लेकिन विभिन्न पोषी निचों पर कब्जा कर लेती हैं। जैसे गैलापैगोस द्वीप समूह के डार्विन के फिंच। ये पक्षी एक ही वंश के हैं और एक ही सामान्य आवास में रहते हैं, लेकिन उनके खाने की आदतों, अर्थात पोषन स्थिति में भिन्न होते हैं। एक जाति शाकाहारी है, जो कलियों और फलों को खाती है, और दूसरी कीटभक्षी है, जो विभिन्न आकार के कीड़ों को खाती है। एक कठफोड़वा फिंच है, जिसकी चोंच लकड़ी पर चोंच मारने जैसी होती है।)
iii. Hypervolume Niche (Multidimensional Niche) हाइपरवॉल्यूम निच (बहुआयामी निच):- It represents the position of a species in the environmental gradient. There are a large number of environmental factors, both abiotic and biotic, that affect the population. This is the fundamental niche of the species and refers to the totality of abiotic and biotic factors to which a given species is uniquely adapted.
(यह पर्यावरणीय प्रवणता में एक जाति की स्थिति का प्रतिनिधित्व करता है। बड़ी संख्या में पर्यावरणीय कारक हैं, अजैविक और जैविक दोनों, जो जनसंख्या को प्रभावित करते हैं। यह जाति का मौलिक निच है और सभी अजैविक व जैविक कारकों को संदर्भित करता है जिसके लिए एक दी गई जाति विशिष्ट रूप से अनुकूलित होती है।)
iv. Fundamental Niche (आधारभूत निच):- It is recognized by Hutchinson. The fundamental niche of a species is the hypervolume that a population can fill in the absence of competitors. So each species has a fundamental niche within a community.
(इसे हचिंसन ने पहचान दी है। किसी जाति का आधारभूत हाइपरवॉल्यूम है जिसे एक आबादी प्रतिस्पर्धियों की अनुपस्थिति में भर सकती है। इसलिए प्रत्येक जाति का एक समुदाय के भीतर एक मौलिक स्थान होता है।)
v. Realized Niche (वास्तविक निच):- It is also recognized by Hutchinson. Because of competition, due to similar essentials along the niche dimension, the competitor niches will be overlying one another. As a result of these biotic constraints, only a part of the niche is realized by the species. These smaller hyper volumes occupied by a species are termed the realized niche.
(इसे भी हचिंसन ने पहचान दी है। प्रतिस्पर्धा के कारण, निच आयाम में समान अनिवार्यताओं के कारण, प्रतिस्पर्धी क्षेत्र एक-दूसरे पर अध्यारोपित हो जाएंगे। इन जैविक बाधाओं के परिणामस्वरूप, जातियों द्वारा निच का केवल एक हिस्सा ही उपयोग किया जाता है। किसी जाति द्वारा कब्जा किए गए इन छोटे हाइपर वॉल्यूम को वास्तविक निच कहा जाता है।)
Relationship Between Habitat and Niche (आवास और निच के बीच संबंध):-
> Habitats can exist without niches. Habitat is the sum of all conditions for an animal to live in (potential habitat).
[आवास बिना निचों के भी अस्तित्व में रह सकते हैं। आवास किसी जन्तु के रहने के लिए सभी स्थितियों (संभावित आवास) का योग है।]
> A habitat is only engaged (realized habitat) when an ecosystem grows, and niches are integrated into it. This is called habitat differentiation and is deeply interconnected with the presence of a thriving ecosystem.
[एक निवास स्थान केवल तभी उपयोग होता है (वास्तविक निवास स्थान) जब एक पारिस्थितिकी तंत्र बढ़ता है, और इसमें निचे एकीकृत होते हैं। इसे आवास विभेदीकरण कहा जाता है और यह एक संपन्न पारिस्थितिकी तंत्र की उपस्थिति के साथ गहराई से जुड़ा हुआ है।]
> It is possible that two animals can have the same niche (same role) in an ecosystem, provided they live in various habitats. For example, deer and rabbits both play the role of herbivores (an animal that feeds only on plants), but you find deer in the woody areas of a forest while rabbits are found in the open areas.
[यह संभव है कि किसी पारिस्थितिकी तंत्र में दो जंतुओं की एक ही निच (समान भूमिका) हो सकती है, बशर्ते वे विभिन्न आवासों में रहते हों। उदाहरण के लिए, हिरण और खरगोश दोनों शाकाहारी (जन्तु जो केवल पौधों पर भोजन करते हैं) की भूमिका निभाते हैं, लेकिन आपको हिरण जंगल के जंगली इलाकों में मिलते हैं जबकि खरगोश खुले इलाकों में पाए जाते हैं।]
Difference between Habitat and Niche (आवास और निच के बीच अंतर):-
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What Would Happen if Organisms Evolved into the Same Niche and the Same Habitat?
(यदि जीव एक ही निच और एक ही आवास में विकसित हों तो क्या होगा?)
> When two animals occupy the same niche in the same habitat, they begin to contest.
(जब दो जन्तु एक ही आवास में एक ही निच पर कब्जा कर लेते हैं, तो वे प्रतिस्पर्धा करना शुरू कर देते हैं।)
> If deer were brought into an open area, both deer and rabbits would begin to fight for the same system.
(यदि हिरणों को खुले क्षेत्र में लाया जाए, तो हिरण और खरगोश दोनों एक ही व्यवस्था के लिए लड़ना शुरू कर देंगे।)
> Eventually, one would get rid of the other (survival of the fittest) or develop a new niche within a niche.
[अंततः, एक को दूसरे से छुटकारा मिल जाएगा (योग्यतम की उत्तरजीविता) या एक निच के भीतर एक नया निच विकसित होगा।]
> Hence, niches play a major role in keeping the diversity alive in a species.
(इसलिए, किसी जाति में विविधता को जीवित रखने में निच प्रमुख भूमिका निभाते हैं।)
> Niches ensure organisms have definite roles and the roles do not overlap to escape competition and elimination.
(निच यह सुनिश्चित करते हैं कि जीवों की निश्चित भूमिकाएँ हों और भूमिकाएँ प्रतिस्पर्धा और उन्मूलन से बचने के लिए अध्यारोपित न हों।)
Plant succession (पादप अनुक्रमण):- A series of changes in an ecological system across time. It is the process of gradual replacement of one plant community by another plant community which is of stable type.
(समय-समय पर पारिस्थितिक तंत्र में परिवर्तनों की एक श्रृंखला। यह एक पादप समुदाय की दूसरे पादप समुदाय द्वारा क्रमिक प्रतिस्थापन की प्रक्रिया है जो स्थायी प्रकार का होता है।)
3 types of communities are developed in plant succession (पादप अनुक्रमण में 3 प्रकार के समुदाय विकसित होते हैं):-
i. Pioneer community (अग्रणी समुदाय):- It is the first plant community which develops in a bare area.
(यह पहला पादप समुदाय है जो बंजर क्षेत्र में विकसित होता है।)
ii. Seral communities (सीरल समुदाय):- These are the plant communities that develop during the succession.
(ये वे पादप समुदाय हैं जो अनुक्रमण के दौरान विकसित होते हैं।)
iii.Climax community (चरमोत्कर्ष समुदाय):- It is the last invading community.
(यह अंतिम आक्रमणकारी समुदाय होता है।)
Causes of Plant succession (पादप अनुक्रमण के कारण):-
i. Initial or initiating causes (प्रारंभिक या शुरुआती कारण):- These causes include both biotic and climatic. It has factors like erosion, wind, fire, natural disasters, etc. These causes heavily affect the population of that locality.
(इन कारणों में जैविक और जलवायु दोनों शामिल हैं। इसमें कटाव, हवा, आग, प्राकृतिक आपदाएं आदि जैसे कारक हैं। ये कारण उस इलाके की आबादी को भारी प्रभावित करते हैं।)
ii. Ecesis causes (इकैसिस कारण):- These causes are also known as continuing causes. These can modify the population to adapt to several conditions of the environment. It includes several factors like aggregation, competition, migration, etc.
(इन कारणों को सतत कारणों के रूप में भी जाना जाता है। ये पर्यावरण की कई स्थितियों के अनुकूल होने के लिए जनसंख्या को रूपांतरित कर सकते हैं। इसमें एकत्रीकरण, प्रतिस्पर्धा, प्रवासन आदि जैसे कई कारक शामिल होते हैं।)
iii. Stabilizing causes (स्थायीकरण कारण):- These causes bring stability to the communities. It has several factors like the nature of the climatic condition of the area, fertility of land and abundance of availability of minerals, etc.
(ये कारण समुदायों में स्थिरता लाते हैं। इसके कई कारक हैं जैसे क्षेत्र की जलवायु स्थिति की प्रकृति, भूमि की उर्वरता और खनिजों की प्रचुर उपलब्धता आदि।)
Process of Plant succession (पादप अनुक्रमण की प्रक्रिया):- It consists of nine steps -
(इसमें नौ चरण होते हैं -)
i. Nudation (बंजरीकरण):- It is the development of bare area or nudation without any form of life. It may be caused due to several factors like volcanic eruptions, landslides, floods, erosion, earthquake, forest fire, the spread of disease, etc.
(यह जीवन के किसी भी रूप के बिना बंजर क्षेत्र या बंजरीकरण का विकास है। यह कई कारकों के कारण हो सकता है जैसे ज्वालामुखी विस्फोट, भूस्खलन, बाढ़, कटाव, भूकंप, जंगल की आग, रोग का फैलना आदि।)
ii. Migration (प्रवास):- It is the arrival of reproductive bodies or propagules of various species in the new or bare area occurs by air, water, etc.
(इसमें नए या बंजर क्षेत्र में विभिन्न जातियों की जनन संरचनाओं या प्रवर्धों का आगमन हवा, जल आदि के माध्यम से होता है।)
iii. Germination (अंकुरण):- It is the settlement of reproductive bodies or propagules of various species in the new or bare area occurs by air, water, etc.
(यह नए या बंजर क्षेत्र में विभिन्न जातियों की जनन संरचनाओं या प्रवर्धों का स्थिरीकरण है जो हवा, जल आदि द्वारा होता है।)
iv. Ecesis (इकैसिस):- It is the adjustment of establishing species with the prevailing conditions.
(यह मौजूदा परिस्थितियों के साथ जातियों की स्थापना का समायोजन है।)
v. Colonization and Aggregation (कॉलोनीकरण और एकत्रीकरण):- Individual species are multiplied by reproduction and increase their numbers.
(व्यक्तिगत जातियाँ जनन द्वारा बहुगुणित होती हैं और उनकी संख्या में वृद्धि होती है।)
vi. Competition and Co-action (प्रतिस्पर्धा और सहयोग):- The individuals of a species compete with other organisms for food, space and other resources. The intraspecific and interspecific competition takes place along with interaction with the environment.
(एक जाति के जीव भोजन, स्थान और अन्य संसाधनों के लिए अन्य जीवों के साथ प्रतिस्पर्धा करते हैं। पर्यावरण के साथ अंतःक्रिया के साथ-साथ अंतरजातीय और अंतराजातीय प्रतिस्पर्धा होती है।)
vii. Invasion (आक्रमण):- New invasion by plants and animals takes place.
(पौधों और जंतुओं द्वारा नया आक्रमण होता है।)
viii. Reaction (अभिक्रिया):- It is the modification of the environment through the influence of living organisms on it.
(यह जीवित जीवों के प्रभाव के माध्यम से पर्यावरण का रूपान्तरण है।)
ix. Stabilization (स्थायीकरण):- The stage at which the final or climax community becomes more or less stabilized for a longer time in that particular environment.
(वह चरण जिस पर अंतिम या चरमोत्कर्ष समुदाय उस विशेष पर्यावरण में लंबे समय तक अधिक या कम स्थायी हो जाता है।)
Types of succession (अनुक्रमण के प्रकार):-
1. Based upon origin (उत्पत्ति के आधार पर):- 2 types - (2 प्रकार)
a. Primary succession (प्राथमिक अनुक्रमण):- It starts in a barren area, never having vegetation of any type where no living organism ever existed. It is a slow process. It usually takes several hundred to a thousand years.
(इसकी शुरुआत एक बंजर क्षेत्र से होती है, जहां किसी भी प्रकार की वनस्पति नहीं होती, जहां कभी कोई जीवित जीव मौजूद नहीं था। यह एक धीमी प्रक्रिया है. इसमें आमतौर पर कई सौ से एक हजार साल लग जाते हैं।)
barren areas (बंजर क्षेत्र):-
i. Newly exposed seafloor (नव उजागर समुद्री तल)
ii. Igneous rocks (आग्नेय चट्टानें)
iii. Sand dunes (रेत के टीले)
iv. New cooled lava sediments (नई ठंडी लावा तलछटें)
v. Newly submerged areas (नये जलमग्न क्षेत्र)
b. Secondary succession (द्वितीयक अनुक्रमण):- It starts in areas that somehow lost all the living organisms that existed there. It is a fast process. It usually takes 50-100 years to complete a grassland and 100-200 years to develop a forest.
(यह उन क्षेत्रों से शुरू होता है जहां किसी तरह वहां मौजूद सभी जीवित जीव नष्ट हो गए थे। यह एक तेज़ प्रक्रिया है। आमतौर पर एक घास के मैदान को पूर्ण करने में 50-100 साल और एक जंगल को विकसित करने में 100-200 साल लगते हैं।)
Causes of destruction of the previous community (पूर्व समुदाय के विनाश के कारण):-
i. Forest fire (जंगल की आग)
ii. Flooded lands (बाढ़ग्रस्त भूमि)
iii. Landslides (भूस्खलन)
iv. Earthquakes (भूकंप)
v. Drought (सूखा)
vi. Overgrazed areas (अतिचारा क्षेत्र)
vii. Storms (तूफान)
2. Based upon factors responsible for environment changes (पर्यावरण परिवर्तन के लिए उत्तरदायी कारकों पर आधारित):-
a. Autogenic succession (ऑटोजेनिक अनुक्रमण):- The succession in which organisms themselves bring change in the environment during succession. The organisms cause change in the soil.
(वह अनुक्रमण जिसमें जीव-जन्तु अनुक्रमण के दौरान स्वयं पर्यावरण में परिवर्तन लाते हैं। जीव-जंतु मृदा में परिवर्तन का कारण बनते हैं।)
Changes in the soil (मृदा में परिवर्तन):-
i. Accumulation of organic matter in form of humus or litter.
(ह्यूमस या कूड़े के रूप में कार्बनिक पदार्थ का संचय।)
ii. Alteration of soil nutrients.
(मृदा के पोषक तत्वों में परिवर्तन।)
iii. Change in pH of soil.
(मृदा के pH में परिवर्तन।)
b. Allogenic succession (एलोजेनिक अनुक्रमण):- The succession in which external environmental factors cause change in the environment during succession.
(वह अनुक्रमण जिसमें बाह्य पर्यावरणीय कारक अनुक्रमण के दौरान पर्यावरण में परिवर्तन का कारण बनते हैं।)
Factors which cause changes in the soil (कारक जो मृदा में परिवर्तन का कारण बनते हैं):-
i. Soil erosion (मृदा अपरदन)
ii. Leaching (लीचिंग)
iii. deposition of silt (गाद का जमाव)
iv. Clays (चिकनी मृदा)
v. Animals (जन्तु):- They act as pollinators, seed dispersers and herbivores. They can also increase nutrient content of the soil in certain areas.
(ये परागकारक, बीज फैलाने वाले और शाकाहारी के रूप में कार्य करते हैं। ये कुछ क्षेत्रों में मृदा में पोषक तत्वों की मात्रा भी बढ़ा सकते हैं।)
3. Based upon habitats (आवास के आधार पर):-
a. Hydrosere or Hydrarch (हाइड्रोसीयर या हाइड्रार्च):- Succession occurs where water is plenty, e.g. pond.
(अनुक्रमण वहां होता है जहां जल प्रचुर मात्रा में होता है, जैसे तालाब।)
b. Xerosere or Xerarch (जीरोसीयर या जीरार्च):- Succession occurs on dry habitat.
(अनुक्रमण शुष्क आवास पर होता है।)
i. Lithosere (लिथोसीयर):- Succession on newly exposed rock surface.
(नई उजागर चट्टान की सतह पर अनुक्रमण।)
ii. Psammosre (सेमोसीयर):- Succession which occurs on sand dunes.
(अनुक्रमण जो रेत के टीलों पर होता है।)
iii. Halosere (हेलोसीयर):- Succession which occurs on saline soil.
(अनुक्रमण जो लवणीय मिट्टी पर होता है।)
iv. Oxylosere (ओक्सीलोसीयर):- Succession on acidic soil.
(अम्लीय मृदा पर अनुक्रमण।)
Food Chain (खाध्य शृंखला):- Flow of energy in an ecosystem is one way process. The sequence of organism through which the energy flows, is known as food chain.
(किसी पारिस्थीतिक तंत्र में ऊर्जा का प्रवाह एक तरफ़ा प्रक्रिया है। जीवों का वह क्रम जिसके माध्यम से ऊर्जा प्रवाहित होती है, खाद्य श्रृंखला कहलाती है।)
> Food chains were first introduced by the Arab scientist and philosopher Al-Jahiz in the 10th century and later popularized in a book published in 1927 by Charles Elton, which also introduced the food web concept.
(खाद्य श्रृंखलाएं पहली बार 10वीं शताब्दी में अरब वैज्ञानिक और दार्शनिक अल-जाहिज़ द्वारा पेश की गईं और बाद में चार्ल्स एल्टन द्वारा 1927 में प्रकाशित एक पुस्तक में लोकप्रिय हुईं, जिसने खाद्य वेब अवधारणा भी पेश की।)
> Each food chain is made up of different trophic levels.
(प्रत्येक खाद्य श्रृंखला विभिन्न पोषक स्तरों से बनी होती है।)
> Each organism represents a trophic level.
(प्रत्येक जीव एक पोषक स्तर का प्रतिनिधित्व करता है।)
> Each organism obtains energy from the organism of its lower trophic level.
(प्रत्येक जीव अपने निचले पोषक स्तर के जीव से ऊर्जा प्राप्त करता है।)
> Plants are called producers because they create their own food through photosynthesis.
(पौधों को उत्पादक कहा जाता है क्योंकि वे प्रकाश संश्लेषण के माध्यम से अपना भोजन स्वयं बनाते हैं।)
> Animals are consumers because they cannot create their own food, they must eat plants or other animals to get the energy that they need.
(जन्तु उपभोक्ता होते हैं क्योंकि वे अपना भोजन स्वयं नहीं बना सकते, उन्हें आवश्यक ऊर्जा प्राप्त करने के लिए पौधों या अन्य जंतुओं को खाना पड़ता है।)
Trophic levels in a food chain (खाद्य श्रृंखला में पोषक स्तर):- Each food chain is made up of different trophic levels. Each organism represents a trophic level. They are represented as T1, T2, T3 etc.
(प्रत्येक खाद्य श्रृंखला विभिन्न पोषक स्तरों से बनी होती है। प्रत्येक जीव एक पोषक स्तर का प्रतिनिधित्व करता है। इन्हें T1, T2, T3 आदि के रूप में दर्शाया जाता है।)
a. Producers (उत्पादक) (T1)
b. Consumers (उपभोक्ता):-
i. Primary consumers (प्राथमिक उपभोक्ता) (T2)
ii. Secondary consumers (द्वितीयक उपभोक्ता) (T3)
iii. Tertiary consumers (तृतीयक उपभोक्ता) (T4)
iv. Quaternary consumers (चतुर्थक उपभोक्ता) (T5)
c. Decomposers (अपघटक)
Types of Food Chain (खाध्य श्रखला के प्रकार):-
Soil pollution:- It refers to the contamination of soil with anomalous concentrations of toxic substances.
Sources of soil pollution:-
1. Agricultural sources:- Agricultural practices such as the use of non-organic products in crop and livestock production lead to soil pollution. These substances include artificial chemical pesticides, herbicides, fungicides, and fertilizers, as discussed below:
a. Pesticides, herbicides, and insecticides:-
> The introduction of modern pesticides, herbicides, and insecticides has resulted in an increase in the use of agricultural chemicals. These chemicals are used to control the pests, insects, weeds, fungi, and diseases that attack crops.
> Most of these chemicals are non-biodegradable, while others decompose to products that are toxic to soil. These products seep into the ground and act on the soil, thereby changing its structure, composition, and pH.
b. Improper use of fertilizer:-
> Fertilizers are mostly used to correct the deficiency of soil nutrients. A soil that is deficient of potassium, calcium, nitrogen, and sulfur, among other important macro-nutrients, should be treated with the right fertilizer and at the right amount.
> However, some farmers use fertilizers indiscriminately, leading to soil pollution. What is more, the materials used to manufacture fertilizers contain impurities that add to soil toxicity. For instance, the rock phosphates mineral used for the manufacture of mixed fertilizers contain traces of Asbestos, Cadmium, and Lead, which are transferred to the fertilizer during production. These metals are non-biodegradable and, with time, accumulate to toxic levels.
2. Industrial sources:-
> Industrial wastes or byproducts are among the leading causes of soil pollution. They can be in the form of gas, liquid, or solid substances. Carbon dioxide, nitrogen dioxide, sulfur dioxide, and carbon monoxide are some of the gases produced from industrial activities that cause considerable pollution to soil indirectly.
> These byproducts combine with the rainwater causing the production of acidic rain, which changes the soil pH and, after that, affects the overall crop production. Industries also dump their solid and liquid effluents into the soil.
3. Urban waste:-
> Most developing countries have a problem controlling the disposal of municipal garbage. The garbage is dumped anyhow and contains wastes such as food waste, plastics, industrial wastes, e-waste, and general household wastes.
> It appears as if the urban administrators do not know that most of the non-biodegradable waste materials could be recycled and the organic materials disposed of in areas designated for natural decomposition.
4. Sewer sludge:-
> Sewage plants also contribute to soil pollution owing to how they dispose of sewage sludge from domestic and commercial waste. The sewage sludge is usually treated before being disposed of into land or water bodies.
> When disposed of on land, the sludge can release high amounts of nutrients depending on the source that may surpass the natural soil nutrient requirement, thus posing a risk to human health and/or the ecosystem at large. Sewer sludge may also contain high levels of metals, further polluting the soil.
5. Mining and Smelting sources:-
> Mining activities cause soil pollution on a large scale. The operations cause a change of the landscape and expose the previously undisturbed soils to the elements of weather.
> Erosion of the soil containing some traces of mineral ores and fine materials around the mining areas results in sediment loading in the water sources and drainage ways. They end up in the soil through irrigation and flowing stormwater.
> There are also other hazardous materials that leak from mining activities, including harmful dust particles that are deposited on the surrounding soils. In developing countries, the pollution levels are even higher because activities such as gold mining are done using traditional methods, which lead to the release of mercury and other heavy metals into rivers and neighboring lands.
> Some of the polluted rivers are also used for irrigation, further leading to the pollution of the irrigated soils.
6. Nuclear sources:-
> Every living organism is continuously exposed to background radiation. If the levels of these radiations exceed a given limit, they lead to disastrous effects. Radiation pollution results from two sources, that is, the natural and anthropogenic actions.
> In nature, there are radioactive minerals that contribute to soil pollution such as radionuclides of radon-222 and Radium -226, Thorium, Uranium, isotopes of Potassium (K-40) and Carbon (C-14) are commonly found in soil, rock, water and air. All the radionuclides deposited on the soil emit gamma radiations.
> The explosion of hydrogen weapons and cosmic radiations include neutron, proton reactions by which Nitrogen (N-15) produces C-14. This C-14 participates in Carbon metabolism of plants, which is then transmitted into animals and human beings.
> Radioactive waste contains several radionuclides such as Strontium90, Iodine129, Cesium-137 and isotopes of Iron, which are most injurious. Strontium gets deposited in bones and tissues instead of calcium.
> Improper disposal of wastes from nuclear reactors containing Ruthenium-106, Iodine-131, Barium140, Cesium-144 and Lanthanum-140 along with primary nuclides Sr-90 with a half-life 28 years and Cs-137 with a half-life 30 years can, therefore, result in soil pollution and contamination.
> Rainwater carries Sr-90 and Cs-137 to be deposited on the soil, where they are held firmly with the soil particles by electrostatic forces.
7. Deforestation:- Though not a direct contributing factor to soil pollution, deforestation leads to the removal of the shield that protects the soil against the agents of erosion. The exposed soil is easily eroded and exposed to artificial chemical pollutants from the air, wind, and rain.
8. Biological agents:- Soil gets a large amount of human, animal and bird excreta, which constitute a major source of land pollution by biological agents.
9. Acid rain:- When pollutants in the air such as sulfur dioxide and nitrogen oxide mix with rain acid rain occurs, which has been found to impact soil negatively by dissolving important nutrients and even changing the soil’s structure.
Causes of soil pollution:-
1. Industrial Pollution:- The discharge of industrial waste into soils can result in soil pollution. In India, as mining and manufacturing activities are increasing rapidly, soil degradation is also increasing. The extraction of minerals from the earth is responsible for affecting soil fertility. Whether it is iron ore or coal, the by-products are contaminated, and they are disposed of in a manner that is not considered safe. As a result, the industrial waste stays on the soil surface for a long duration and makes it unsuitable for further use.
2. Agricultural Activities:- The use of insecticides and pesticides for a long period can cause soil pollution. Repetitive use can cause insects and pests to become resistant to it. Instead of killing pests and insects, it degrades the soil quality. They are full of chemicals that are not produced in nature and cannot be broken down by them. As a result, they seep into the ground after they mix with water and slowly reduce the fertility of the soil. Plants absorb many of these pesticides, and after decomposition cause soil pollution.
3. Waste Disposal:- Disposal of plastics and other solid waste is a serious issue that causes soil pollution, disposal of electrical items such as batteries causes an adverse effect on the soil due to the presence of harmful chemicals. Eg: lithium present in batteries can cause the leaching of soil. Human waste such as urine, faeces, diapers, etc is dumped directly in the land. It causes both soil and water pollution.
4. Acid Rain:- It is caused when pollutants present in the air mix with the rain and fall back on the ground. The polluted water could dissolve away some of the essential nutrients found in soil and change the structure of the soil thus making it unsuitable for agriculture.
5. Heavy Metals:- The presence of heavy metals (such as lead and mercury) in very high concentrations present in soils can cause them to become highly toxic for human beings.
6. Nuclear Waste:- It can also lead to soil degradation.
7. Oil Spills:- Oil leaks can happen during the storage or transport of chemicals, the chemicals present in the fuel deteriorates the quality of soil and make them unsuitable for further cultivation, chemicals can also enter into the groundwater through the soil, and hence it will make water undrinkable.
Control of soil pollution:- Soil pollution is a complex issue that must be addressed. It is important that we all understand the importance of soil to our survival. The earlier we recognize the problem, the simpler it will be to solve the problem of soil pollution. It's a complicated problem that requires everyone's participation, from individuals to the government.
A few methods for reducing soil pollution are listed below.
1. Reduced Use of Chemical Fertilizers:- Chemical fertilizers are more damaging than helpful. While the right quantity can help the soil become more fertile, too much might potentially poison it. Chemical fertilizers in excess could harm the soil in a variety of ways. It has the ability to affect the soil's pH values.
2. Reforestation and Afforestation Should be Promoted:- Soil erosion, which is produced by deforestation, is one of the major sources of soil pollution. With an ever-increasing population, it is only logical that mankind requires more and more room to expand their civilization. It is frequently accomplished at the expense of soil health. Reforestation of a deforested area should be encouraged to prevent this from happening.
3. Recycle and Reuse Products:- These measures not only reduce waste output, but they also reduce soil pollution. Plastic now makes up a significant portion of the waste flow. The great majority of these wastes are buried in landfills.
4. Promote Use of Natural Manure:- One of the best sources of nutrients for the soil is natural manure. It's 100% natural and safe. It restores the soil's critical nutrients and improves its overall health. It doesn't produce any toxic by-products that could harm the soil or the environment.
Effect of Air Pollution on Plants:-
1. Damaging the plants:- Air pollution means the introduction of harmful chemicals into the air, like sulfur, nitrogen oxides and carbons. These chemicals cause damage to plants, with the plants physically showing the damage in a variety of ways, for instance through stunted growth, necrotic lesions, and changes in colors. Change in color could be represented by chlorosis which is when plant leaves turn yellow, reddening, mottling or bronzing.
2. Obstructing a plant’s growth:- Ozone is harmful to the atmosphere as it leads to holes in the upper atmosphere. In doing so, ultraviolet light is able to pass through the atmosphere, causing further damage to plants. Destruction by the ozone in the lower atmosphere restricts respiration, obstructs stomata, prevents photosynthesis and stunts plant growth.
3. Reduced yields and damage to crops:- Plants absorb pollutants from the air, making the air cleaner. With a build-up of too many pollutants, plants may fail to grow as they should, including being unable to perform photosynthesis. This, in turn, will mean plants will fail to have fewer yields than they should. Reduced yields especially in agricultural crops will mean hunger for the people and animals, and will also drive prices of such commodities up, destabilizing the economy.
4. Contributing to global warming:- With air pollution affecting plants and their leaves, it means they will be unable to absorb carbon dioxide as they should. This means more carbon dioxide will escape into the atmosphere, which will further damage the ozone layer, and cause a build-up of more greenhouse gases. This will also contribute to global warming and subsequently climate change.
Effect of Water Pollution on Plants:-
1. Denying plants essential nutrients:- Plants require specific nutrients, which they get from the soil, water and air. Polluted waters might kill some of those nutrients, further denying the plant the ability to get them.
2. Poisoning the soils:- Water pollution will introduce toxins that are harmful to plants. An accumulation of such toxins in the water will poison the soils even for other crops or plants. This will in turn negatively affect the solubility of essential nutrients and ions, like magnesium, calcium and potassium, which are particularly vital for proper plant growth. Water pollution also introduces large amounts of aluminum to the soil, which harms plants.
3. Facilitating the growth of rival plants:- Water pollution gives rise and ample room for other plants to grow. These new plants may not be native to a region and could be detrimental to the existing plants. These weeds will grow well because the nutrients they require for survival are collected in the polluted water.
4. Killing and harming plants:- Water pollution changes the growing conditions of plants, including eroding necessary nutrients and bringing in new and hazardous ones. This means the normal growth of plants will be affected and the plants themselves will be harmed. If the condition is persistent, the plants will eventually die. Water pollution can also alter a plant’s surrounding pH levels, such as acid rain, which also harms and kills plants.
Effect of Soil Pollution on Plants:-
1. Poisoning the soils:- Toxins will enter the soil and poison it, causing a chain reaction. The result will be an alteration in the soil’s biodiversity, reduction in the soil’s organic matter, as well as its capacity to act as a filter. With regards to plants, the soil becomes weak and is not able to sustain plants as compared to previous years. This explains why most farms which rely on fertilizers, have been giving out lower yields year after year. Soil pollution increases the salinity of the soil making it unfit for vegetation, thus making it useless and barren.
2. Poisoning the plants:- As mentioned underwater pollution, toxins poison the soil and in turn, poison the plants themselves. Land pollution through oil spills, pesticides, landfills, illegal dumping and many other sources results in chemicals seeping into the soil and eventually into the plants. These chemicals and metals damage plant cells and hinder them from obtaining the necessary nutrients for growing. This explains why soil pollution also leads to lower yields and poor quality harvests.
3. The effects reach our food chain:- Soil pollution, affects plants, meaning they will absorb the pollutants. If we feed on such plants or crops, like vegetables, we inadvertently end up poisoning ourselves. It also means we do the same by consuming animal products like meat and milk if the animals themselves fed on these compromised plants.
4. Affecting waterways:- When the soil is contaminated, water that is stored in the soil and below it is also affected, causing a lot more issues. This water is used by millions directly and indirectly. The indirect part is that other people will grow crops using the same contaminated water, spreading the problem to more people who may be many miles away.
Effect of air pollution on animals:-
1. Altered animal behavior:- An increasing number of studies demonstrated that pollutants can trigger bizarre behavior in animals. For example, endocrine disruptors, heavy metals, and PCBs have a direct influence on the social and mating behaviors of animals.
2. Diseases and Mortality:- In most cases, the effect is indirect but slowly kills animals by disrupting biological processes. Air pollutants disrupt endocrine function, cause organ injury, increase vulnerability to stresses and diseases, lower reproductive success. Prolonged exposure to air pollutants can increase the expression of markers of neurodegenerative disease pathologies.
3. Biodiversity loss:- Air pollution is a major driving force changing the basic structure and function of ecosystems. For example, excess deposition of airborne nitrogen (N) in the form of ammonia is among the main stressors to biodiversity. Biodiversity is critical for animals because an impairment can result in alterations in the food chain and loss of certain species. Biodiversity loss can also increase the risk of infectious diseases.
4. Change in species distribution:- Industrial air pollution can cause a change in the abundance of a particular species. For example, the loss of certain fish species due to higher aluminum levels may allow insect species to increase, which may in turn benefit ducks that feed on insects. But this loss could be detrimental to eagles, ospreys, and other animals that depend on fish as their food.
Effect of water pollution on animals:-
> Chemical contaminants carried by industrial wastes kill a lot of smaller aquatic organisms, such as frogs, fish, tadpoles, etc. This, in turn, causes a loss of food source for bigger aquatic creatures, leading them to either consume poisoned, dead fish and perish, or leave their natural habitat to go in search of food in other aquatic quarters. Often, this leads to sickness and death of these animals due to the inability to adapt to changed water temperatures, unfavorable tides, as well as exposure to new predators.
> An excess of nutrients, such as nitrogen and phosphorus in the water, leads to an increased growth of toxic algae and aquatic plants, that cause poisoning and death in fish and other animals who feed on them.
> Presence of huge quantities of mercury in water has led to a lot of undesirable changes in aquatic species. Too much mercury leads to hormonal imbalances and glandular damage, leading to abnormal behavioral shifts. Also, mercury is a toxic metallic chemical that gives a huge blow to the reproductive functions, growth and development of animals, that are continuously exposed to high doses of it.
> Oil spills that introduce unhealthy amounts of oil into the marine environment also make marine animals sick and lead to their unnatural deaths.
> Dumping solid trash such as plastic, metallic scrap, garbage, etc., may block aquatic channels, and can also cause small animals to get trapped in the debris. Most water-dwelling animals tend to suffocate or drown on being trapped and unable to swim.
> Polluted water used for irrigation also contaminates the soil and the agricultural produce. This may lead to health issues in herbivorous animals who feed on agricultural plants and leftovers.
> These pollutants can radically alter the metabolism of a number of soil-dwelling bacteria and insects, making them perish or unsuitable for consumption by common predators of the local ecosystem.
> Atmospheric pollutants may get mixed with clouds and fall back on earth as acid rain. This toxic shower is potent enough to inflict mortal injuries to any life form that gets exposed to it.
Effect of noise pollution on animals:-
> Animals rely heavily on sounds to communicate, to find food, avoid predators etc.
> Pets react more aggressively due to exposure to constant noise. They become disoriented more easily and face many behavioral problems.
> Overexposure to high intensity of noise affects the hearing ability of many animals.
> Man-made noise affects mating calls and echolocation. This leads to reduction in survival and reproduction rates.
> At an ecosystem level, noise pollution could lead to migration of animals. Their migration can affect the crop production. Because many animals such as bats pollinate bananas, peaches, agave and other cash crops.
Resources:- All the materials present in our environment which are used by living beings. These are very useful raw materials found in the environment.
Natural Resources:- Humans require many useful things available in nature to live on this planet. These are referred to as natural resources.
Types of Natural Resources:- The most general category is the amount of resources available for human consumption. They are two types:
1. Renewable resources
2. Non-renewable resources
1. Renewable resources:- Those resources that cannot be depleted. They are always available and thus could be reused. They can be replenished or renewed naturally over time.
i. Solar energy:- Sun is a big source of energy. The energy that we get from the Sun is called solar energy. All the natural phenomenon like the flowing of wind, water cycle, photosynthesis etc are possible only due to solar energy. Now a day, solar energy is being used to cook food with the help of solar cookers, heat water, light streets, pump water for irrigating fields etc.
ii. Hydro-Energy:- Water is important natural resources. All living organisms need water to live. Humans need water for many purposes such as drinking, cleaning, cooking and for growing crops. Water flowing into the river or water stored in a dam is sources of hydro energy. The Simple method to use hydro energy is to convert it into electrical energy.
iii. Wind energy:- Winds are constantly being created in nature. The windmill is a source of electrical energy. These windmills are generally established only at places where most of the days in a year experience strong winds. The energy from this wind is used for grinding grain, pumping water and to produce electricity. In India, many windmills have been set up in different places such as Tamil Nadu, Maharashtra, Rajasthan, Kerala, West Bengal and Gujarat.
iv. Biogas:- Biogas is a type of fuel which is a mixture of gases such as methane, carbon dioxide, hydrogen etc which is obtained by decomposition of animal and plant wastes like animal dung, with the help of micro-organisms in the presence of water. It is used as fuel in gas stove especially in rural areas.
v. Wood:- Wood is an ancient and traditional source of energy. It is mainly a mixture of many carbohydrate compounds. Wood is used to cook food. It leads to deforestation and pollutes air also. In India, still in many villages, they use wood chullas to cook food every day. While having ill effects on the environment, it is also harmful to human health.
vi. Hydrogen:- It is a good source of energy because it does not create pollution and produce maximum energy on burning. Hydrogen has the potential to be the answer to all our energy and fuel troubles. Technology is currently being developed to fully utilize hydrogen efficiency.
vii. Alcohol:- Alcohol has many commercial and medical purposes. It can use for producing energy. It can be obtained while making sugar from sugarcane. Thus it is a very cheap source of energy. A mixture of petrol and alcohol is being used as a fuel in automobiles. This mixture is called ‘Gasohol’.
viii. Air:- All living things need air to breathe. Therefore, air is an important natural resource.
ix. Water:- All living things water in order to survive. And the water cycle means we will essentially never run out of the water. But we must be careful not to pollute water and make it unusable. Drinking and clean water are already scarce in the world.
x. Soil:- It is an important resource as this is the layer where plants grow. We all need food in order to survive. We get most of our food from crops grown in the soil.
2. Non-renewable resources:- Those natural resources that are available in limited quantity. These resources cannot be renewed or replenished in short duration. Therefore they are also known as exhaustible resources.
a. Fossil fuel:- Fossil fuels like coal and petroleum are non-renewable resources. They are found deep inside the earth and are made by natural processes over many centuries. Their quantity is limited and they take thousands of years to get renewed. Example of fossil fuels is coal, petroleum, natural gas etc.
i. Coal:- It is also known as black diamond. Coal is used as a fuel, to generate electricity, and in factories and steam engines.
ii. Natural gas:- Natural gas is used as a fuel called Compressed Natural Gas or CNG. Some wells dug into the earth produce only natural gas. Natural gases are a good alternative to petrol and diesel and it is used as Compressed Natural Gas. It burns easily and produces a lot of heat. It is a good source of hydrogen.
iii. Petroleum:- Petroleum is also known as mineral oil or crude oil. This liquid mineral is refined to make fuels such as petrol, diesel, cooking gas and kerosene. Plastic, cosmetics, and lubricants are also products of petroleum. It is found deep inside the Earth or under the sea floor. It is taken out by drilling wells deep into the Earth or under the seabed.
b. Nuclear energy:- In the classification of resources, nuclear energy is classified as non-renewable. The fuel used for nuclear energy is generally uranium, which is in a limited supply. So we classify it as non-renewable. Production of electricity from nuclear energy does not release carbon dioxide. Thus, use of nuclear energy is safe for the environment.
Distribution of vegetation:-
a. Continuous distribution
b. Discontinuous distribution
a. Continuous distribution:- Some taxa are uniformly distributed in the area and give rise to continuous distribution. The area of a taxon or of a vegetation feature is never really continuous. It is of four main types:
i. Cosmopolitan:- These taxa are distributed all over the globe. They occur in all six widely inhabited continents, Eg.- many weeds and lower groups of cryptogams.
ii. Circumpolar:- These taxa are distributed around the North or South Pole Eg.- Saxifraga oppositaefolia, Eutrema edwardsii.
iii. Circumboreal:- These taxa are distributed around the boreal zone Eg.- Ribes (Gooseberries) and Danthonia (poultry grass).
iv. Pantropic:- These taxa occurring practically throughout the tropics and sub-tropics or at least widespread in the tropical region of Asia, Africa and America, Eg.- Palm family (Arecaceae).
b. Discontinuous distribution:- Most taxa may have isolated patches of areas widely separated apart. These constitute discontinuous distribution pattern. The plants are separated by wider gaps which cannot be overcome or crossed by the propagules. The main causes of discontinuity are environmental (due to particular topographic, climatic, edaphic or biotic characteristics of tracts separating the areas). Following are the familiar discontinuous types:
i. Arctic – Alpine:- Taxa are distributed in arctic region and in mountainous system of temperate zone. Eg.- Salix herbacea, Saxifraga oppositaefoilia.
ii. North Atlantic:- Taxa are distributed in North America and Europe and also some times locally in Asia. Eg.- Lycopodium inundatum and Spiranthes sp.
iii. North Pacific:- Taxa are distributed chiefly in North America and Eastern Asia, Eg.- Torreya (Torrey pine) Symplocarpus foetida.
iv. North—South American:- Taxa are distributed in North and South America but lacking continuity in between, Eg.- Sarraceniaceae (pitcher-plant family)
v. Europe – Asian:- Taxa are distributed in Europe and Asia but lacking continuity between. Eg.- Leontice altaica, Cimicifuga foetida.
vi. Mediterranean:- Taxa are distributed at European and African shore of Mediterranean sea. Eg.- Platanus
vii. Tropical:- Taxa are distributed in two or more separate tropical regions. Eg.- Buddleia
viii. South pacific:- Taxa are distributed at least in South America and New Zealand. Eg.- Jovellana
ix. South Atlantic:- Taxa are distributed at least in South America and Africa. Eg.- Asclepias
x. Antarctic:- Taxa are distributed on Arctic mainland and parts of South America, New Zealand and Austral islands. Eg.- Nothofagus
xi. Gondwana type:- Taxa are distributed in more than one continent which tends to embrace Africa, Madagascar, India and Australia. Eg.- Some sedges.
Geographical barriers:- They include the formation of a mountain range, the movement of a glacier, and the division of a large lake into several smaller lakes.
> Ecologists who study biogeography examine patterns of species distribution.
> No species exists everywhere; for example, the Venus flytrap is endemic to a small area in North and South Carolina.
> Endemic species:- It is one which is naturally found only in a specific geographic area that is usually restricted in size.
> Generalized species:- Species which live in a wide variety of geographic areas. The raccoon, for example, is native to most of North and Central America.
> Species distribution patterns are based on biotic and abiotic factors and their influences during the very long periods of time required for species evolution. Therefore, early studies of biogeography were closely linked to the emergence of evolutionary thinking in the eighteenth century.
> Some of the most distinctive assemblages of plants and animals occur in regions that have been physically separated for millions of years by geographic barriers.
> Biologists estimate that Australia, for example, has between 600,000 and 700,000 species of plants and animals. Approximately 3/4 of living plant and mammal species are endemic species found solely in Australia.
> Sometimes ecologists discover unique patterns of species distribution by determining where species are not found. Hawaii, for example, has no native land species of reptiles or amphibians, and has only one native terrestrial mammal, the hoary bat. Most of New Guinea, as another example, lacks placental mammals.
> Plants can be endemic or generalized.
> Endemic plants are found only on specific regions of the Earth, while generalists are found on many regions.
> Isolated land masses—such as Australia, Hawaii, and Madagascar—often have large numbers of endemic plant species.
> Some of these plants are endangered due to human activity. The forest gardenia (Gardenia brighamii), for instance, is endemic to Hawaii, only an estimated 15–20 trees are thought to exist.