Ch. 2— Importance of Biological Diversity • 39 



BENEFITS TO ECOLOGICAL PROCESSES 



Ecological processes include— 



• regulation: monitoring the chemistry and 

 climate of the planet so it remains habitable; 



• production: conversion of solar energy and 

 nutrients into plant matter; 



• consumption: conversion of plant matter 

 into animal matter; 



• decomposition: breakdown of organic 

 wastes and recycling of nutrients; 



• protection processes: protection of soil by 

 grasslands and forests and protection of 

 coastlines by coral reefs and mangroves, 

 for example; and 



• continuation of life: processes of feeding, 

 breeding, and migrating. 



Knowledge of the relationship between di- 

 versity and ecological processes is fragmentary, 

 but it is clear that diversity is crucial to the func- 

 tioning of all major life processes, for diversity 

 helps maintain productivity and buffers eco- 

 systems against environmental change. Diversity 

 within ecosystems is essential for protective, 

 productive, and economic benefits. Species 

 diversity is necessary for a stable food web. And 

 diversity of genetic material allows species to 

 adapt to changing environmental conditions. 



Ecosystem Diversity 



Ecosystems are systems of plants, animals, 

 and micro-organisms, together with the non- 

 living components of their environment (45). 

 It can be recognized on many scales, from 

 biome— the largest ecological unit— to micro- 

 habitat (box 2-B). Ecosystem diversity refers to 

 the variety that occurs within a larger land- 

 scape. Loss of ecosystem diversity can result 

 in both the loss of species and genetic resources 

 and in the impairment of ecological processes. 



In eastern and southern Africa, for instance, 

 the mosaic of ephemeral ponds, flood plains, 

 and riparian woodlands enable antelope, ele- 

 phant, and zebra to survive long cycles of wet 

 and dry years (16,23). On the American conti- 

 nent, many animal species cope with oscilla- 

 tions in weather and climate by migrating be- 

 tween biomes— spending the rainy season in 



Box 2-B. — Scales of Ecosystem Diversity 



Several ways exist to classify the many 

 scales of ecosystem diversity. An example 

 using the Pacific Northwest to illustrate four 

 levels of ecosystems is shown below. Animal 

 species characteristic of each level are noted. 



1. Biome: temperate coniferous forest 

 —Rufous hummingbird 

 — Mountain beaver 



2. Zone: western hemlock 

 — Coho salmon 

 —Oregon slender salamander 



3. Habitat: old growth forest 

 — Vaux's swift 

 — Spotted owl 



4. Microhabitat: fallen tree 

 —Clouded salamander 

 —California red-backed vole 



The fallen tree component of old growth and 

 mature forests illustrates the contribution of 

 ecosystem diversity to ecological processes. 

 Fallen trees provide a rooting medium for 

 western hemlock and other plants that is moist 

 enough for growth to continue during the sum- 

 mer drought, a reserve of nitrogen and other 

 nutrients, and a source of food and shelter for 

 animals and micro-organisms that play key 

 roles in redistributing and returning the nu- 

 trients to the regenerating forest. For exam- 

 ple, the rotten wood provides habitat for truf- 

 fles, and the truffles are eaten by the California 

 red-backed vole, which spreads the truffle 

 spores, so helping the growth of Douglas fir 

 trees, which require mycorrhizal fungi (such 

 as truffles) for uptake of nutrients (56). 



the tropical dry forest and the dry season in 

 the rain forest, that is, summer in temperate 

 forest and winter in tropical forest. Others use 

 different habitats within the same biome; for 

 example, leaf-eating primates and flower-pol- 

 linating bats move from dry sites in the rainy 

 season to evergreen riparian trees in the dry 

 season (32,48). 



Several types of ecosystems are closely asso- 

 ciated with protective and productive processes 

 of direct economic benefit. Cloud forests, for 



