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| Description: In chapters 19 and 20 we have provided a foundation for understanding the most basic ecosystem functions: primary production and nutrient cycling. We have discussed how these ecosystem services can be altered by human activities, by the abiotic environment, and by interactions within the ecosystems themselves. The question I am sure that many of you are asking is, so what? Although nutrient cycling is widely recognized by ecologists as one of the most critical aspects of ecosystem ecology, and that alteration of the rates of decomposition can have cascading effects altering a variety of other ecological interactions and patterns of diversity, this message is not often clearly transmitted to undergraduate students and the general population. Instead, decomposition is often viewed as among the dullest of subjects: studying things we can't see eating things that are dead. Why on earth would anyone want to devote their life to the study of the rate at which dead leaves and roots turn into CO2 and other molecules? The answer, quite simply, is that changes in decomposition will more directly and indirectly alter processes humans care about (such as climate change and biomass production) than nearly any other ecological process you will find in this book. Certainly, studying bear and elk in a national park is a great life, and understanding the ecology of these organisms is a worthwhile endeavour. However, a 10% increase or decrease in predation rates or population sizes of these charismatic creatures isn't going to have any impact on global processes. A 10% change in decomposition will. Here we discuss one such example: the potential impact of altered rates of decomposition in the arctic and sub-arctic regions of the world. As we saw in chapters 2 and 3, northern regions are home to large expanses of peatlands and deep organic soils. Additionally, these regions represent a large portion of the land mass on the planet. These areas are also quite cold for much of the year, and in many areas deep layers of permafrost keep the layers of the ground frozen year round (fig. 20.11). What actually is frozen in the north? Is it simply clay, sand, and other layers of mineral soil? No. Although soil particles are certainly frozen, much of the permafrost contains organic matterâ€â€Âdead plants, animals, bacteria, and fungi. Put another way, the north is home to an enormous pool of frozen carbon, which could potentially be liberated into the atmosphere with a bit of liquid water and some warming. Let's try to put this into a larger perspective.
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