New classification systems for tropical organic-rich deposits based on studies of the Tasek Bera Basin, Malaysia

Most schemes in common use for field and laboratory classification of peats were developed in boreal and humid temperate regions and do not recognize the distinctive features and specific uses of tropical peats, such as those of the Tasek Bera Basin in tropical Peninsular Malaysia. The important aspects of peat texture (morphology of constituents and their arrangement) and laboratory ash content (residue after ignition) need modification to be valuable for classifying these and other tropical peat deposits. In the Tasek Bera Basin, most of the deposits would not be considered as peat according to some classification schemes, even though most have C contents >25%. We propose a new three-group (fibric, hemic, sapric) field texture classification applicable to tropical organic deposits, which is similar to the system of the US Soil Taxonomy. The classification is based on the following factors: (1) visual examination of the morphology of the peat constituents (texture); and (2) estimates of fiber content and matrix (finest fraction of peat consisting of highly humified organic matter and inorganic material). The classification is applicable to all organic deposits with <65% ash (i.e., >35% loss on ignition). We also present a new laboratory classification of organic soils based on ash and C content. The US Soil Taxonomy classifies organic soils as having more than 12–18% organic C, depending on clay content. Ash content and these limits for organic soils allow the discrimination of four main groups: peat, muck, organic-rich soil/sediment and mineral soil/sediment. Peat is defined as having an ash content of 0–55%, muck 55–65%, organic-rich soil/sediment 65–80% and mineral soil/sediment 80–100%. The peat class is further subdivided into very low ash (0–5%), low ash (5–15%), medium ash (15–25%), high ash (25–40%) and very high ash (40–55%) subclasses

Stream closure and water allocation in the Colombian Andes

In the Andean region water for human activities is commonly extracted from small streams. When water is abundant, equity considerations in water allocation arrangements are not apparent; but when streams approach closure, a closer look at water distribution and use are necessary to diagnose and address allocation concerns. This paper presents a case study in the Colombian Andes where water during periods of scarcity is not equitably distributed, disproportionally impacting rural users that depend on agricultural activities for their livelihoods. Although concessions do not allocate water on a first come first served basis, the distribution system favours urban over rural users. It is argued that allocation of water should be based on reliable information regarding water availability, the physical infrastructure for storage and distribution, and the water use requirements of different land use activities

Assessing the Potential for Pocket Agriculture in Mountainous Regions: A Case Study in West Kootenay, British Columbia, Canada

Food security is a growing concern for rural communities that rely on imported food. Increasing a region's food self-reliance is a strategy to address this concern, but is a challenge in regions with limited arable lands as a result of topographically diverse, mountain-dominated landscapes. Mechanized, large-scale agriculture relies on contiguous areas of arable land, rather than small parcels of dispersed arable soils and suitable climates. The Kootenay region of British Columbia, Canada, serves as an example of the opportunities for mountainous, rural communities to increase their food self-sufficiency by considering the potential for agriculture on small parcels of land. Soil capability survey maps that provide a biophysical assessment of arable lands were used as a basis for determining (a) the potential land base available for small-scale agriculture, and (b) the potential for niche crops that may be grown on poorer capability lands in the Kootenay region. The soil capability criteria, coupled with farm survey data, were used to measure and quantify the distribution of underutilized farmland in the region. Results indicate that up to 90 percent of land capable of agriculture and 69 percent of high quality farm land protected under the Agricultural Land Reserve is not under production for crops or pasture. Global Climate Model scenarios for 2050 indicate that the region will have a longer growing season, hotter summers, and more frost-free days, which could increase the region's capacity to grow food but might require additional water for irrigation. The assessment suggests that soil surveys based on biophysical attributes can assist mountainous regions in assessing their potential for agriculture

VIRTUAL WATER: A FRAMEWORK FOR COMPARATIVE REGIONAL RESOURCE ASSESSMENT

New developments in water resource allocation techniques range from local management of green water to international trade in water. A further extension of this is through the virtual water concept, which is the water required to produce a crop or product. The virtual water content of many products is now available at a national and global scale. While these calculations are meaningful in international trade debates, they are not useful to water managers since regional climatic and management conditions are highly variable. The utility of the virtual water concept at a smaller scale is illustrated by a comparison of agricultural crops in the driest and wettest agro-climatic regions in Canada. Results were compared to national and international global calculations. The calculations are highly sensitive to local conditions, and locally collected data needs to be aggregated and compared in order to be made useful to water managers and land use planners.Virtual water, resource assessment, water footprint, crop water requirement, British Columbia

Tree diversity, site index, and carbon storage decrease with aridity in Douglas-fir forests in western Canada

Forests are important for biodiversity, timber production and carbon accumulation, but these ecosystem services may be impacted by climate change. Field data collected from individual forest types occurring across a climatic gradient can contribute to forecasting these consequences. We examined how changes in temperature, precipitation and aridity affect ecosystem services in 23 mature Douglas-fir (Pseudotsuga menziesii) forests in nine climatic regions across a 900 km gradient in British Columbia, Canada. Using Canadian National Forest Inventory methodology, we assessed richness and diversity of plant functional groups, site index, and above- and below-ground carbon stocks. As aridity increased, ecosystem-level tree species richness declined on average from four to one species, Douglas-fir site index declined from 30 to 15 m, and ecosystem carbon storage decreased from 565 to 222 Mg ha-1. Tree species richness was positively and herb species richness negatively correlated with carbon storage. Carbon storage by ecosystem compartment was largest in aboveground live tree biomass, declining in the following order: mineral soils > coarse woody debris and dead standing trees > forest floor > small and fine woody debris > understory plants. Mineral soil carbon at depths of 0-15 cm, 15-35 cm, and 35-55 cm increased with increasing mean annual precipitation and decreasing aridity. Our results indicate that as aridity increases and precipitation decreases, tree species richness, site index and carbon storage in existing Douglas-fir forests declines. However, assisted or natural migration of Douglas-fir into more humid regions could be associated with more diverse, productive, carbon-rich forests. This study informs carbon stock vulnerability and provides empirical data essential for carbon stock forecasts