Soil and Plant Analysis for Forest Ecosystem Characterization

Daniel John Vogt, Joel P. Tilley, Robert L. Edmonds, Higher Education Press

• Publisher: De Gruyter
• Year: 2015
• ISBN:
  9783110381764
• Edition: 1
• Topic: Biological Sciences
• Subtopic: Environmental Science
• Index: Biological Sciences

This handbook provides an overview of physical, chemical and biological methods used to analyze soils and plant tissue using an ecosystem perspective. The current emphasis on climate change has recognized the importance of including soil carbon as part of our carbon budgets. Methods to assess soils must be ecosystem based if they are to have utility for policy makers and managers wanting to change soil carbon and nutrient pools. Most of the texts on soil analyis treat agriculture and not forest soils and these methods do not transfer readily to forests because of their different chemistry and physical properties. This manual presents methods for soil and plant analysis with the ecosystem level approach that will reduce the risk that poor management decisions will be made in forests. This manual was intended for the instructors that teach students soil and plant analyses; however it can also be used by the research laboratories and by environmental scientists. The laboratory procedures in this manual are outlined in easy-to-follow steps and frequently accompanied with examples of calculations, questions to answer, and also a blank data sheet to use. These methods used in this manual can be used on soil and plant tissues found in agricultural, horticulture, forestry, urban, and natural lands.

Part I

Context of Soil and Plant Analysis

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Chapter 1

Overview of Soil and Plant Analysis for Forest Ecosystems

Humans have become one of the greatest engineers of change to the land and the environment. No other organism has altered its degrees of freedom as drastically as humans. In fact, humans have altered up to 80% of the temperate broadleaved forests and from 25% to 46% of the tropical forests ^[1]. Today, we are asking many questions regarding environmental issues. These issues include: where and how we can detect, monitor, or measure the impacts of land-use changes or the conversion of land archaeas to different vegetation communities and what will be their effects on our environment. These human land-uses changes have triggered many alterations to soil conditions or its health and have also affected what vegetative community will be able to grow or dominate in a particular landscape (see Fig. 1.1).

The connection between forests and soils is especially apparent from looking at the factors that caused past human societies to collapse. Most of the examples that exist are a result of each society altering the soils chemical, biological or physical characteristics due to resource over-exploitation, e.g., intensive deforestation or intensive and long-term agricultural practices. These land-use activities were followed by a significant change in climate, usually a drought or excessive rainfall, which caused the collapse of the society. It is important to note that generally these negative changes in the soil were only recognized to have contributed to societal collapse after some unusual climatic event, such as a mega-drought or excess rainfall. Several recorded examples of societal collapse linked to human’s treatment of the land are:

• – More than 4,000 years before the current epoch the Sumerians of Mesopotamia (modern day Iraq and portions of Syria, Turkey and Iran) cut down cedar forests in the mountains to build their civilization. The hillsides and mountainous areas were bared and the salt-rich sedimentary rocks of the north rapidly eroded into their agricultural fields. This erosion, plus the salts that were transported to their lands, decreased agricultural production by 42% ^[3],[4]. This is the first recorded case of erosion resulting from land-use activities contributing to the collapse of a civilization ^[5].
• – The Nazca people of Peru lived in a dry forest area dominated by Prosopis pallid. This tree played a vital role in maintaining the habitat because its extensive roots pumped water from deep aquifers to the surface of the ground. To expand their agricultural fields, they cut down the trees. This deforestation was followed by a mega El Niño event that hit the southern coast of Peru in about 500 CE and brought excess precipitation. The Nazca’s agricultural fields were washed away because the soil’s stability was lost without the stabilizing effect of the P. pallid forests ^[6].
  

  Fig. 1.1 Factors of human land uses and their influences on our natural ecological systems including soils (modified from Global Land Project ^[2]).
• – The civilization living on Easter Island (off the western coast of South America) collapsed around 900 CE. One theory suggested that they also collapsed because of deforestation that caused soil erosion during rain and windstorms ^[7]. This deforestation also caused the loss of soil carbon and the leaching of soil nutrients so that agricultural production collapsed ^[7]. Deforestation was a result of a rivalry between clans based on which clan could sculpt and transport the largest statue to their territory (immense 8 meter high stone statues called moai). According to Diamond ^[7], trees from their forests were cut to build massive sleds to hold the statues while fibrous tree bark was used to make ropes to pull each statue from the quarry to its intended site. The size of these statues required from 50 to 500 people to move them.
• – The Maya civilization (situated in the southern part of Mexico and large parts of Central America) collapsed between 1,020 and 1,100 CE after an extended period of drought ^[8]. This was preceded by “anomalously high rainfall, which favored unprecedented population expansion and the proliferation of political centers between 440 and 660 CE” ^[8]. This period of population expansion and economic development resulted in over-exploitation of their forests to build their economies. By losing their forests, they lost the buffering that forests would have provided them against the drought.

Even if soil degradation wasn’t the main causal factor of the societal collapse, degraded soils were frequently a major component of societies not being sustainable. Because of the importance of soils to humans, methodology books have been developed to not only present methods for analyses but also to ensure standardization so that relative and valid assessments can be made. These books describe soil and plant analyses and provide a context wherein all possible assessments are considered to help determine which sampling and analytical methodologies should be used. This context helps explain why soils, plants, their interconnectivities, and their analyses are an important element of our assessment toolkit. Soil and plant connections are not just relevant in human managed landscapes but are also part of connections and processes that occur in the natural environments. The natural environment generally maintains a threshold for nutrient applications to any ecosystem so that luxury levels do not pollute our environments. Soil and plant analyses are therefore useful to warn of ecosystems’ approaching the tipping point at which nutrient levels become deficient and will decrease plant growth rates. Thus they can be important explanatory factors or indicate causal drivers of changes that occur in our environment due to multiple human and non-human factors. These analyses can allow humans to assess whether land-use practices may become negative and perhaps even decrease both social and environmental resiliencies. These tools become extremely important given the fact that the Earth has 7 billion plus mouths to feed and its soil health has changed in our attempt to provide the needed food.

One only has to read reports such as the Millennium Ecosystem Assessment [9] put out by the United Nations or the Global Land Project ^[2] to comprehend the large-scale changes to the environment that are attributed to human activities. These changes are occurring globally. Climate change also aggravates and further reduces soil health and its productivity following the impacts that have already resulted from previous land-use changes. This means that there is a need to acquire a better grasp regarding the links between soil conditions and climate change and disturbances in general. Research at the plot level has shown the links that exist between altered soil conditions and the productive capacity of vegetative communities. However, when comparisons are made at a country level, which is the most common scale used, it is difficult to link land-use changes to the loss of a lands productive capacity. When Vogt et al. ^[10] compared nine indices characterizing a country’s environmental and social ranking for 34 countries, few links were identified between the land degradation severity ranking ^[11] and a countries performance index, its total ecological footprint, its environmental vulnerability index, or its global climate risk index. This seems to indicate that the scale at which soils are included in global assessment may have little value in detecting the loss of environmental or social resilience due to land-use activities. However, this is not correct and merely shows that soils are primarily included in environmental assessments at a scale too coarse to perceive any relationships. To observe the relationships between land-use or climate change and soils, the soil analysis should be conducted at the scale where these interconnectivities can be detected, e.g., soil texture groups. The scale of the disturbance may be less relevant since each soil type will respond differently to a disturbance as well as the vegetative community that grows on that soil. It follows then that soil characteristics can determine the inherent limitations of any land and how that land will respond to climate change disturbances.

It is well ac...

Table of contents

• Ecosystem Science and Applications
• Title Page
• Copyright Page
• Acknowledgments
• Acronyms
• Table of Contents
• List of Tables
• Table of Figures
• Table of Contents
• Part I - Context of Soil and Plant Analysis
• Part II - Introductory Methods in Soil and Plant Analyses
• Part III - Soil Physical, Chemical and Biological Analyses
• Appendices
• References
• Subject Index