Benjamin R. Stinner

Invertebrates as bioindicators of soil use

Abstract We face an increasing demand from administrative, technical and environmental authorities for bioindicators. Animals, plants and community patterns, which register quantitative and qualitative environmental changes need to be monitored. This can range from simple chemical and physical sampling to quantifying the patterns of animal and plant communities. These techniques for analysing soil communities were first developed for aquatic systems. Protozoans, earthworms, woodlice, myriapods, Acari, springtails and other groups of invertebrates seem to respond to chemical residues and other environmental stresses in many different ways. Although a rich literature on interactions is available, only limited information exists at the community level and little is known of the food chain level in the soil. Research is needed to find appropriate patterns which could model different situations.

Agroecosystem biodiversity: matching production and conservation biology

Abstract A review of the existing literature on biodiversity connected with agricultural activities has been developed, and the possible sustainable alternatives have been looked into. Following recent evaluations, only one-twentieth to one-sixtieth of the planets species have yet been described and most of these will be lost if the destruction of the environment continues at its present rate. Most of the terrestrial environment (up to 95%) is affected by human activities including agriculture and the terrestrial habitats provide up to 98% of human food on the planet. Sustainable strategies in food production in agriculture improve the existing biodiversity and include the following items: increased porosity of the landscape through proper management of natural vegetation, better use and recycling of organic residues, introduction of integrated farming systems, reduced tillage, rotation, biological control, increased number of biota involved in human food-webs.

Diversity of soil fauna in the canopy and forest floor of a Venezuelan cloud forest

Arboreal and terresterial soil and lilter were sampled for macro-and microinvertebrates at two locations in a Venezuelan cloud forest. Fauna were most abundant in forest floor soil and associated litter. However, media suspended in the canopy and particularly those trapped in bromeliad shoots were most densely populated, while the diversities of the arboreal and terrestrial soil fauna were indistinguishable. Rates of leaf litter decomposition in the arboreal and terrestrial soils were similar, but the arboreal soils contained higher concentrations of mineral nutrients and carbon. Implications of these findings for the definition of soil in humid tropical forests, and related differences between temperate and tropical forests are discussed. The similarities in diversity and differences in species composition between arboreal and terrestrial soil fauna raise questions concerning the evolution of tropical soil fauna, as well as the estimate of global biotic diversity.

Biodiversity as an organizing principle in agroecosystem management: Case studies of holistic resource management practitioners in the USA

Abstract Holistic Resource Management (HRM) is a process of goal setting, decision making and monitoring which integrates social, ecological and economic factors. Biodiversity enhancement is a fundamental principle in HRM and students are taught that biodiversity is the foundation of sustainable profit. In the HRM process, practitioners develop a holistic goal which includes: (1) quality of life values, (2) forms of production to support those values, and (3) landscape planning, which should protect and enhance biodiversity and support ecosystem processes of succession, energy flow, hydrological and nutrient cycling. We present an overview of the HRM model and results of interviews with 25 HRM farmers and ranchers from across the USA in which perceptions and experiences with respect to the role of biodiversity in the sustainability of their operations were explored. An ethnographic approach and qualitative research methods were used in the interviews. While only 9% of the interviewees reported thinking about biodiversity in the context of their operations before being exposed to HRM, now all of them think biodiversity is important to the sustainability of their famrs and ranches. Of the people interviewed, 95% perceived increases in biodiversity (particularly with respect to plants) and 80% perceived increase in profits from their land since HRM began influencing their decisions. In addition to perceiving increases in biodiversity, all of the interviewees reported observing indications of positive changes in some of the ecosystem processes on their farms or ranches. In addition, 91% of the interviewees reported improvements in their quality of life because of changes in their time budgets. Three of the interviewees who had quantitative data on changes in numbers of plant species and economic indicators are discussed in detail. We conclude that holistic management approaches like HRM are worthy of further study.

Corn and weed residue decomposition in northeast Ohio organic and conventional dairy farms

Increasingly, farmers claim that management practices can significantly influence soil quality. For instance, it is common practice for dairy farms in their rotation cycle to harvest grain and then leave stubble and weeds over winter on the soil surface before ploughing in spring ahead of planting crops. Corn stubble and weeds protect soil in winter, decompose through the seasons, and release nutrients that are utilized by crops and microorganisms. Also, plant residues may harbor increased soil decomposing organisms that feed up on them. Both conventional and organic farmers tend to follow these practices with the major difference that in the conventional systems, inorganic fertilizers and pesticides are applied. Organic matter breakdown in soils under different management (organic versus conventional as in this case) may be different because some inorganic chemicals are known to affect soil decomposers and also these might be less abundant in soils with less food resources, since the organic farmers rely totally on soil fertility derived from organic source. This hypothesis was tested in an on-farm decomposition study conducted in an organic and a conventional farm that grew corn (Zea mays L.) for dairy cattle feed, in Wayne County, OH. Mesh bags containing crop and weed residues were laid on the soil surface at the onset of winter and sampled thereafter to determine decomposition. Mass loss was significantly different among substrates, with crop residues decomposing faster than weeds. Mass and nitrogen (N) loss varied among substrates and variations were greater in summer. Between farms mass and N loss were significantly higher in the organic farm in summer. Earthworm population density was significantly higher in the organic farm. In summary, corn residues decomposed faster than weed residues, and differences in decomposition among substrates increased in summer. Decomposition was faster in summer at both farms, however, it was higher at the organic one, where more soil decomposers were found. The higher metabolic activity in the soil of the organic farm in warmer weather suggests a more active soil biota, which may be crucial for farms whose main or sole source of nutrients derives from organic matter decomposition.

Implications of Land Use Changes on Carbon Dynamics and Sequestration—Evaluation from Forestry Datasets, India

Forests and soils are a major sink of carbon, and land use changes can affect the magnitude of above ground and below ground carbon stores and the net flux of carbon between the land and the atmosphere. Studies on methods for examining the future consequences of changes in patterns of land use change and carbon flux gains importance, as they provide different options for CO2 mitigation strategies. In this study, a simulation approach combining Markov chain processes and carbon pools for forests and soils has been implemented to study the carbon flows over a period of time. Markov chains have been computed by converting the land use change and forestry data of India from 1997 to 1999 into a matrix of conditional probabilities reflecting the changes from one class at time t to another class time t+1. Results from Markov modeling suggested Indian forests as a potential sink for 0.94 Gt carbon, with an increase in dense forest area of about 75.93 Mha and decrease of about 3.4 Mha and 5.0 Mha in open and scrub forests, if similar land use changes that occurred during 1997–1999 would continue. The limiting probabilities suggested 34.27 percent as dense forest, 6.90 as open forest, 0.4 percent mangrove forest, 0.1 percent scrub and 58 percent as non-forest area. Although Indian forests are found to be a potential carbon sink, analysis of results from transition probabilities for different years till 2050 suggests that, the forests will continue to be a source of about 20.59 MtC to the atmosphere. The implications of these results in the context of increasing anthropogenic pressure on open and scrub forests and their contribution to carbon source from land use change and forestry sector are discussed. Some of the mitigation aspects to reduce greenhouse gas emissions from land use change and forestry sector in India are also reviewed in the study.