CARBON STORAGE AND SEQUESTRATION IN TEA

AGROFORESTRY SYSTEM IN BARAK VALLEY, ASSAM

A THESIS SUBMITTED TO ASSAM UNIVERSITY

IN PARTIAL FULFILMENT OF THE REQUIREMENT FOR THE

DEGREE OF DOCTOR OF PHILOSOPHY IN THE DEPARTMENT OF

ECOLOGY AND ENVIRONMENTAL SCIENCE

By

RINKU MONI KALITA

Ph.D. Registration No. : Ph.D/1202/2010. dated 28.07.2010

DEPARTMENT OF ECOLOGY AND ENVIRONMENTAL SCIENCE

E.P.ODUM SCHOOL OF ENVIRONMENTAL SCIENCES

ASSAM UNIVERSITY, SILCHAR

ASSAM – 788011(INDIA)

2015

iii

Acknowledgements

Foremost, I would like to acknowledge my supervisor Prof. Ashesh Kumar Das for his

guidance, constant inspiration, effective suggestions and motivation throughout my

research tenure. It has been a great pleasure to work with him. I learnt so many things

from him, not only related to research but also in real life. He has taught me to overcome

difficulties with patience. His curiosity and kindness inspire an environment that

encourages creativity and cooperation. His door was always open for any kind of

discussions even at crucial stage of my Ph. D life.

I would like to express my deepest gratitude to Dr. Arun Jyoti Nath, my supervising co-

guide for constant encouragement and valuable discussions with attention and

professionalism. His efficient guidance, support, moral ethics and patience inspired me

greatly.

I sincerely thank respected Dean, E. P. Odum School of Environmental Sciences,

respected Head of the Department of Ecology and Environmental Science, teachers, non-

teaching staff of the department for providing laboratory and equipment facilities to carry

out experimental studies and kind advice and cooperation. I would also thank Mr. I. B.

Ubhadia, Manager of Rosekandy Tea Estate, Management for valuable cooperation and

the field assistants from Rosekandy and Dorgakona villages for their laborious

cooperation in the field work.

I am grateful to the University Grants Commission (UGC) and Council of Scientific and

Industrial Research (CSIR), New Delhi for financial support to undertake this research

work. The financial assistance provided by the CSIR in the form of SRF in a research

project (Scheme number: 38(1349)/13/EMR-II dt.14.02.2013.) has helped in

strengthening the research through field and laboratory work. The equipment purchased

through CSIR project grant helped in the determination of wood density of trees, canopy

cover estimation and also SOC fraction studies. I would like to acknowledge SAIF

(Sophisticated Analytical Instruments Facility), Cochin University, Kerala, India for

providing CHN analyzer data and Tea Research Association, Cachar Advisory Centre for

providing the meteorological data.

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I would also like to express my sincere thanks to Dr. Dhruba Jyoti Chakraborty, Dr.

Manash Pratim Kashyap and Dr. Hemanta Talukdar for their valuable suggestions for

statistical analyses for the study.

I take this opportunity to thank Dr. Tapasi Das, Dr. Nepolion Borah, Mr. Debajit Rabha,

and all the research scholars of Forest and Agricultural Ecology Laboratory for valuable

suggestions and cooperation during the research work. I also like to express my gratitude

to all my friends, well-wishers for their moral support.

Nothing can be accomplished without family support. So, finally I would like to express

my deep sense of gratitude to my parents and family members for their blessings and

affectionate cooperation which encouraged me to overcome the hurdles on my way.

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CERTIFICATE

Certified that the thesis entitled “CARBON STORAGE AND SEQUESTRATION IN

TEA AGROFORESTRY SYSTEM IN BARAK VALLEY, ASSAM’’ submitted by

Rinku Moni Kalita for award of the Degree of Doctor of Philosophy in Ecology and

Environmental Science is the outcome of a bonafide research work. This work has not

been submitted previously for any other degree of this or any other University. It is

further certified that the candidate has compiled with all the formalities as per the

requirements of Assam University. We recommend that the thesis may be placed before

the examiners for consideration of award of the Ph.D. degree of this University.

(Dr. Arun Jyoti Nath)

Co-Supervisor

Department of Ecology & Environmental

Science, Assam University, Silchar

(Prof. Ashesh Kumar Das)

Supervisor

Department of Ecology & Environmental

Science, Assam University, Silchar

Department of Ecology & Environmental Science

E.P.Odum School of Environmental Sciences

ASSAM UNIVERSITY, SILCHAR

(A Central University constituted under Act XIII of 1989)

Silchar - 788 011, Assam, India

ii

ii

DECLARATION

I, Rinku Moni Kalita bearing Registration No. Ph.D/1202/2010 dated 28/07/2010 hereby

declare that the subject matter of the thesis entitled “CARBON STORAGE AND

SEQUESTRATION IN TEA AGROFORESTRY SYSTEM IN BARAK VALLEY,

ASSAM” is the record of the work done by me and that the contents of this thesis did not

form the basis for award of any degree to me or to anybody else to the best of my

knowledge. The thesis has not been submitted in any other University/ Institute.

Place………….. …. (Rinku Moni Kalita)

Date………………

Department of Ecology & Environmental Science

E.P.Odum School of Environmental Sciences

ASSAM UNIVERSITY, SILCHAR

(A Central University constituted under Act XIII of 1989)

Silchar - 788 011, Assam, India

v

Preface

Global warming risks from emissions of Green House Gases by anthropogenic activities

have increased the need for the identification of the ecosystems with high carbon sink

capacity as an alternative mitigation strategy of terrestrial carbon sequestration. Tea

(Camellia sinensis (L.) O. Kuntze) is an intensively managed perennial cash crop grown

under a canopy of trees. Tea agroforestry system have the potential to sequester a

considerable amount of atmospheric CO2 in the plants as well as in the soil and can be a

preferable option for climate change mitigation coupling economic benefits along with

environmental services. Estimation of the sequestered carbon amount in the tea

agroforestry systems is essential for proper evaluation of their role as carbon sinks. The

present study aimed to assess carbon stock in the biomass and soil in tea agroforestry

system and rate of carbon sequestration in biomass compartments. Biomass estimation

involved development of allometric equations through destructive sampling of tea

bushes. Wood density estimation for the shade tree species was adopted for improved

biomass estimation. The study was carried out by laying 100 quadrats of 0.1 ha size in 25

different plantations representing five different age groups. Estimation of aboveground

biomass, belowground biomass, litter carbon and soil organic carbon have been

undertaken to assess total C pool in tea agroforestry system. Structure and composition,

biomass and carbon stocks, comparative assessment of shade tree growth performance,

soil physicochemical properties, soil organic carbon stock and distribution of different

carbon fractions, rate of biomass carbon sequestration were analysed for plantations of

different ages and represented in illustrations and tabular forms in different chapters.

Chapter 1 is the general introduction, presenting agroforestry and climate change

scenario; brief overview and background on tea agroforestry; its origin and distribution in

the context of India and Barak Valley in Assam. Further this chapter provides details of

the problem statement and research objectives.

Chapter 2 covers a literature review on structure, composition and carbon sequestration in

agroforestry systems, study on tea agroforestry systems processes and productivity and

soil study.

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Chapter 3 covers description of study site, materials and methods of sampling, biomass

estimation and carbon estimation, growth study, canopy cover and wood density study.

The chapter further presents methods for soil physicochemical analysis, carbon

sequestration and carbon di oxide mitigation potential.

In Chapter 4, structure and composition of tea agroforestry system is discussed. Shade

tree canopy cover and girth height relationship of different shade trees is also emphasized

in the chapter.

Chapter 5 reports on assessment of biomass and carbon stock in tea agroforestry system.

The results constitutes of development of allometric equations for tea biomass estimation.

and biomass estimation using volume equations and carbon stock estimation on area basis

have been highlighted in this chapter.

Chapter 6 incorporates assessment of shade tree growth in tea agroforestry system. Size

and species wise growth rate, determination of wood density of shade tree species and

interaction of growth with different parameters have been discussed in details.

Chapter 7 deals with details of soil characteristics and assessment of soil organic carbon

in tea agroforestry system. Assessment of different soil organic carbon fractions up to 1

m depth and relation with physical properties is discussed in chronosequence of different

ages of plantations.

Chapter 8 contains discussion on carbon sequestration in tea agroforestry system. C

sequestration in tea, shade tree and soil compartment, carbon di oxide mitigation by

different compartment is assessed. Rate of carbon di oxide mitigation potential of the

agroforestry system is also mentioned in this part.

Chapter 9, which incorporates the general discussion and conclusions of the study, gives

a synthesis of the results of the different chapters of the thesis following references.