CHAPTER 1 INTRODUCTION

Ecology: Study of relationships between organisms and the environment. Ecosystem: all organisms that live in an area and the physical environment with which those organisms interact. Nutrients: the raw materials that an organisms must acquire from the environment to live.

Ecology Understand the relationships between organisms and the environment. We are not fully understand the relationships and the changes that we do in earth. Broad scientific discipline under ecology (study individuals, entire lake, or even whole earth) Ecologist could study: organisms Non-biological Theoretical models of ecological systems Ecological research in the laboratory

Using Field Studies to test theory Warbler study case 1 Robert MacArthur 1955, bird-watcher test for theory of warbler feeding on insects of spruce trees. Fig. 1.1

Fig. 1.1

Warbler study case 2 Figure 1.2 Douglass Morse 1980, 1989. address questions on feeding zones and whether warblers use the same feeding zones in the absence of others. Compared warbler on mainland to small islands inhabited by one to three species. Feeding zones are partially maintained by aggressive interactions Aggressiveness help maintain different feeding zones. Figure 1.2

Fig. 1.2

Contributions of field and laboratory studies Bumblebees study case Bernd Heinrich (1979, 1993) Combination of laboratory & field study. Measure Energy budget. Oxidation Time of flying Types of flowers visited Figure 1.3, 1.4

Forest Nutrient Budgets Inventories and large-scale experiments 1 Nalini Nadkarni (1981, 1984a, 1984b). Studied budget of nutrients in rain forest of C R. Correlation of epiphytes with nutrient budget. Epiphytes store nutrients estimated to be half of nutrients content of the foliage of the canopy trees. The research showed that ; Both temperate & tropical rain forest, trees access to nutrient stored by epiphytes by sending out roots from their trunks and branches above the ground. The roots grow into the epiphyte mats and extract nutrients from them.

Fig. 1.5

large-scale experiments 2 Gene Likens and Robert Bormann (1994, 1995) Hubbard brook experimental forest of New Hampshire. Their hypothesis suggest that organisms, specially plants will regulate the rate of nutrient loss from forest. Measuring nutrients before and after deforestation. They estimated the rate at which some organisms fix atmospheric nitrogen and rates at which weathering release nutrient from granite bed-rock of the stream basins. They found that over 90% of the nutrients are tied up in soil organic matter. While the rest 9.5% was in vegetation. Following cutting the trees they found that 40-50 of Nitrate where lost. Major elements in stream draining increased by 177% to 1,558%. Show clearly influence of vegetation on nutrient movements.

Fig. 1.6

Vegetation change Information from pollen record and modeling Margaret Davis (1983,1989). Theoretical models provide long-term ecological changes. Study of different lake sediments provide historical changes of vegetations (spatial & temporal). Ecotones : transitions from one type of ecosystem to another (e.g. woodland to grassland or vise versa) Phase transition model include change in the state of matter such as water from liquid to solid state as temperature decrease. Phase transition take place abruptly under some critical condition, water shifts to solid at 0 ° C. Critical densities regulate the transition from one vegetation to another. The research indicated there are a relationships between ecotones and their sensitivities to environmental changes . Also distance between edges are defined by different plant densities. Edges defined by different densities of vegetation are more widely spaced, the environmental gradients is likely to be more gradual.

Fig. 1.8

Fig. 1.9