Role of fine roots and soil microbes in C, N & P dynamics in a humid tropical forest ecosystem of Northeast India

Doctoral Thesis / Dissertation , 2006 , 174 Pages , Grade: none

Biology - Botany

The tropical rainforests are dense, evergreen vegetation characterized by high
diversity of plant and animal species. They are one of the most fragile and complex
terrestrial ecosystems on Earth, presently occupying less than 7% area of Earth’s surface
in America, Southeast Asia and Africa (Richards 1952; Whitmore 1998). Within
continental Asia, patches of tropical rainforests are found in Indo-China, South China and
northeast India (Whitmore 1998). The tropical wet evergreen forest patches also occur in
the Western Ghats of India. In northeast India, tropical rainforests are restricted to the far
eastern part of the region, particularly in Tirap and Changlang districts of Arunachal
Pradesh and Tinsukia and Dibrugarh districts of Assam. Although a major portion of
these forests has been brought under protected area management, they are still threatened
by anthropogenic activities.
Tropical forests worldwide are exposed to a variety of disturbances ranging from
frequent localized events to less frequent, landscape level or multiple disturbance events.
Natural disturbances and concomitant recovery are integral aspects of normal ecosystem
behaviour (White 1979). Human disturbances, on the other hand, differ in kind, scale,
intensity and frequency and sometimes they may be more severe and extensive than the
natural disturbances. Shifting cultivation and extraction of timber and NTFP’s species are
major causes of disturbance in the humid tropics (Reiners 1980), which have destroyed
vast tracts of the humid tropical forest ecosystem. Logging and timber removal or conversion of forest to other land uses has long-term consequences on secondary
vegetation, nutrient cycles and water balance (Turner et al. 1997).
Several workers have reported that removal or loss of forest cover alters physicochemical
characteristics of soil (Joergensen and Raubuch 2002) and adversely affects the
soil hydrological regime, microclimate, energy balance and enhances soil erodibility
(Fenn et al. 1993). Input of organic matter and nutrients to soil through litter and root
mass help improve nutrient availability by favourably altering the hydrology and
physico-chemical and biological properties of the soil. The periodicity, extent and pattern
of litter fall and litter decomposition are important in this respect (Ambasht 1985).[...]

Inhaltsverzeichnis (Table of Contents)

• CHAPTER 1. INTRODUCTION
• CHAPTER 2. REVIEW OF LITERATURE
• CHAPTER 3. STUDY SITE: LOCATION, GEOLOGY AND SITE CHARACTERISTICS
• CHAPTER 4. VEGETATION AND SOIL
• CHAPTER 5. BIOMASS AND NUTRIENT DYNAMICS OF FINE AND COARSE ROOTS
• CHAPTER 6. DYNAMICS OF SOIL MICROBIAL POPULATION AND BIOMASS -C, -N AND -P
• CHAPTER 7. IN SITU N AND P MINERALIZATION
• CHAPTER 8. GENERAL DISCUSSION
• SUMMARY
• REFERENCES

Zielsetzung und Themenschwerpunkte (Objectives and Key Themes)

This doctoral thesis investigates the role of fine roots and soil microbes in the dynamics of carbon, nitrogen, and phosphorus in a humid tropical forest ecosystem in Northeast India. The study aims to understand the interconnectedness of these components within this specific environment. The key themes explored within this research include:

• The biomass and nutrient dynamics of fine and coarse roots in both undisturbed and disturbed stands of the tropical forest.
• The dynamics of soil microbial populations and biomass in relation to carbon, nitrogen, and phosphorus.
• The in-situ rates of nitrogen and phosphorus mineralization in the forest ecosystem.
• The relationship between vegetation characteristics and soil nutrient content.
• The impact of disturbance on the cycling of carbon, nitrogen, and phosphorus within the forest ecosystem.

Zusammenfassung der Kapitel (Chapter Summaries)

• Chapter 1. Introduction: This chapter provides an overview of the significance of tropical forests in global carbon cycling and their importance as biodiversity hotspots. It highlights the crucial role of fine roots and soil microbes in nutrient dynamics within these ecosystems. The chapter outlines the research objectives and the specific questions addressed in the study.
• Chapter 2. Review of Literature: This chapter reviews the existing scientific literature on the role of fine roots and soil microbes in nutrient cycling in tropical forest ecosystems. It focuses on the key processes involved, such as decomposition, mineralization, and nutrient uptake. It also examines the influence of disturbance on these processes and the potential consequences for ecosystem function.
• Chapter 3. Study Site: Location, Geology and Site Characteristics: This chapter describes the study site in Northeast India, including its geographical location, geological history, and specific climatic and edaphic characteristics. It also provides information on the vegetation and soil conditions within the study area.
• Chapter 4. Vegetation and Soil: This chapter presents data on the vegetation and soil characteristics of the study site. It includes detailed information on the species composition, density, and biomass of different vegetation layers. The chapter also analyzes the physical and chemical properties of the soil, highlighting variations between undisturbed and disturbed stands.
• Chapter 5. Biomass and Nutrient Dynamics of Fine and Coarse Roots: This chapter focuses on the biomass and nutrient dynamics of fine and coarse roots in both undisturbed and disturbed stands of the tropical forest. It analyzes seasonal variations in root biomass and production, as well as the accumulation and turnover of carbon, nitrogen, and phosphorus within different root size classes.
• Chapter 6. Dynamics of Soil Microbial Population and Biomass -C, -N and -P: This chapter investigates the dynamics of soil microbial populations and biomass in relation to carbon, nitrogen, and phosphorus. It examines the abundance and activity of bacteria and fungi in different soil depths and stands, as well as the contribution of microbial biomass to the total soil nutrient pool.
• Chapter 7. In Situ N and P Mineralization: This chapter analyzes the in-situ rates of nitrogen and phosphorus mineralization in the forest ecosystem. It examines the effects of season, stand type, and soil depth on mineralization rates and explores the relationships between these rates and soil physico-chemical and microbial characteristics.

Schlüsselwörter (Keywords)

This research focuses on the important ecological processes of carbon, nitrogen, and phosphorus cycling in a humid tropical forest ecosystem of Northeast India. It examines the role of fine roots and soil microbes in these processes, analyzing biomass, nutrient dynamics, microbial population, and in-situ mineralization rates. Key concepts include forest disturbance, ecosystem function, nutrient availability, and the interconnectedness of different components within this tropical forest ecosystem.

• College: North-Eastern Hill University
• Grade: none
• Author: Atiqur Barbhuiya (Author)
• Publication Year: 2006
• Pages: 174
• Catalog Number: V188679
• ISBN (eBook): 9783656144755
• ISBN (Book): 9783656144793
• Language: English
• Tags: role, northeast, india