Academic literature on the topic 'Remnant patches'

Australia's little known woodlands once covered huge areas of the eastern side of our continent. Woodlands are distinguished from forests by the fact that their canopies do not touch, tree heights are usually lower and they usually have a grassy understorey. They support a fascinating and diverse array of birds, mammals, reptiles, frogs, invertebrates and plants, and have been under massive pressure from grazing and agriculture over the past 200 years. In many cases only small remnant patches of some types of woodland survive. Understanding and appreciating woodlands is an important way forwar

Rainbow Beach is a small town on the coastal dunes of eastern Australia, near Brisbane. I had travelled there to meet with some colleagues to sample soils from the vast coastal sand dunes that surround the area. It might seem an unusual place to visit to collect soil, but a unique sequence of soils has formed in the sand dunes, which differ greatly in age. As you move inland from the sea, the soils get progressively older and deeper, and more weathered and nutrient-poor. The youngest soils are shallow, having only just started to form in recent sand dunes, whereas the oldest soils are around half a million years old and can reach 25 metres deep. These are among the oldest, deepest, and most weathered soils that I have sampled, and what I recall most vividly is how stunted and sparse the vegetation was that grew there, reflecting their struggle to grow in such ancient, weathered soil. The soils of Rainbow Beach are by no means the oldest on Earth. Hidden beneath ice sheets in Greenland, scientists recently discovered a soil that was 2.7 million years old, a remnant of the fertile tundra that covered the area before the ice sheets came. And scientists working in South Africa recently discovered a soil, now compacted in rock, that is 3 billion years old. One of the most fascinating things about soil is that it is incredibly diverse; soils vary enormously across continents, countries, and from valley to valley and field to field. Even within a small patch of land, such as a field, forest, or vegetable garden, the underlying soil can vary considerably. Over distances of metres, it might differ in its texture and depth, and in its pH, being acid in one patch of a field and neutral in another. Soils also vary greatly in the diversity of living organisms that live within them. I will go into more detail about the diversity of soil life later in this book; but for now suffice to say that it is vast. Soils also change with time.

Agriculture is the mainstay of Kenya’s economic development and accounts for about 30% of the country’s gross domestic product, 60% of export earnings, and 70% of the labor force. This sector is the largest source of employment (Government of Kenya, 1995). More than 85% of the population survives in one way or the other on agricultural activities (crops and livestock). Agriculture in Kenya is mainly rain-fed, with little irrigation. About 46% of the rural population live below the poverty line, with 70% of them below food poverty line. Like many parts of the tropics, the majority of agricultural activities in Kenya are rain dependent. Small-scale farmers, pastoralists, and wildlife are most often affected by drought, with crops withering and livestock as well as wildlife dying. Drought of more than one season overwhelms the social fabric, as crops, livestock, wild animals, and humans die. Such droughts affect pastoral communities (e.g., the Masai in Kenya and Tanzania) by killing livestock and game animals, forcing these communities to invade the nearby towns and cities to find remnants of patches of grass still left there or grass growing at the roadsides. The death of game animals affects ecotourism. Interannual climate variability that often leads to the recurrence of climate extremes such as droughts has far-reaching impacts on agricultural production. Figure 18.1 shows below-normal rainfall during different years that are often associated with droughts in Kenya. These rainfall deficits are caused by the anomalies in the circulation patterns that can extend from local or regional to very large scales. Some patterns that are responsible for spatial and temporal distribution of rainfall in Kenya include the Intertropical Convergence Zone (ITCZ), subtropical anticyclones, monsoonal wind systems, tropical cyclones, easterly/westerly wave perturbations, subtropical jet streams, East African low-level jet stream, extratropical weather systems, teleconnection with El Niño/Southern Oscillation (ENSO), and quasi-biennial oscillation (Ogallo, 1988, 1991, 1994). In addition, complex physical features such as large inland lakes, mountains, and complex orographic patterns (e.g., the Great Rift Valley) influence rainfall patterns. Lake Victoria in western Kenya is also one of the largest freshwater lakes in the world and has its own strong circulation patterns in space and time.

Regular-fractal topography on RF-switch MEMS surface is reported over different scale ranges. Surface topography is crucial in understanding underling physics associated with the surface contacts, switch working performance, and reliability. The complexity of these structures requires new techniques to characterize topography and then replicate the multi-scale regular-fractal structure for analysis. Topography on RF-switch contacting surfaces are scanned by atomic force microscopy (AFM) at different length scales (e.g. 1×1, 10×10 and 60×60 μm2). A sample allocation plan is designed to maximize