Hunting Increases Dispersal Limitation in the Tree Carapa procera, a Nontimber Forest Product

Abstract:  The sustainability of seed extraction from natural populations has been questioned recently. Increased recruitment failure under intense seed harvesting suggests that seed extraction intensifies source limitation. Nevertheless, areas where more seeds are collected tend to also have more intense hunting of seed-dispersing animals. We studied whether such hunting, by limiting disperser activity, could cause quantitative dispersal limitation, especially for large crops and for crops in years of high seed abundance. In each of four Carapa procera (Meliaceae) populations in French Guiana and Surinam, two with hunting and two without, we compared seed fate for individual trees varying in crop size in years of high and low population-level seed abundance. Carapa seeds are a nontimber forest product and depend on dispersal by scatter-hoarding rodents for survival and seedling establishment. Hunting negatively affected the proportion of seeds dispersed and caused greater numbers of seeds to germinate or be infested by moths below parent trees, where they would likely die. Hunting of seed-dispersing animals disproportionally affected large seed crops, but we found no additional effect of population-level seed abundance on dispersal rates. Consistently lower rates of seed dispersal, especially for large seed crops, may translate to lower levels of seedling recruitment under hunting. Our results therefore suggest that the subsistence hunting that usually accompanies seed collection is at the cost of seed dispersal and may contribute to recruitment failure of these nontimber forest products. Seed extraction from natural populations may affect seedling recruitment less if accompanied by measures adequately incorporating and protecting seed dispersers.     

Sustainable Development and Strategic Thinking

From an economic point of view, the industrial economy is efficient to overcome situations of a scarcity of goods. From a technological point of view, the resource efficiency of the manufacturing processes of the industrial economy has been permanently improved during the last 200 years. In addition, cleaner processes have been developed. However, from an ecologic point of view, an increasing world population with increasing consumption has produced a ＂global footprint＂ which approaches the carrying capacity of the planet. A circular economy and its high-value spin-offs-a lake economy and a performance or functional service economy-can fulfil customers＇ needs with considerably less resource consumption, less environmental impairment in production and considerably less end-of-life product waste, especially in situations of affluence, when a considerable stock of physical goods and infrastructures exists. Also, in situations of a scarcity of natural resources, both energy and materials, often characterised by rapidly rising resource prices, the economic actors of a circular economy have a high competitive advantage over the actors of the industrial economy, due to much lower procurement costs for materials and energy. From a social point of view, a circular economy increases the number of skilled jobs in regional enterprises. However, the shift from a linear manufacturing economy to a circular or service economy means a change in economic thinking from flow （throughput） management to stock （asset） management： in a manufacturing economy with largely unsaturated markets, total wealth increases through accumulation as resource throughput （flow） is transformed into a higher stock of goods of better quality （but in a manufacturing economy with largely saturated markets, wealth represented by the stock of goods will no longer increase）; in a circular or service economy, total wealth increases through a smart management of existing physical assets （stock） that are adapted to changes in both technology and customer demand. This second approach not only applies to physical capital but equally to social capital, such as health and education and green GDP. To measure the social wealth of a population, it is not the amount of money spent on schools and hospitals that matters, butif this expenditure has led to a better education of the students, and a better health of the people.     

Geochemical characteristics of surficial sediments in a tropical estuary, south-west India

Geochemical characteristics of surficial sediments in the Panangad region of Cochin estuary, the largest brackish-water humid ecosystem in the south-west coast of India, were analysed. Temporal variations in nutrient stoichiometry, seasonal characteristics of redox elements Fe and S, and the phosphorus geochemistry were employed for the purpose. The stoichiometric analysis pointed towards autochthonous origin of organic matter, possibility of nitrogen limitation, and allochthonous modification of redox conditions. Seasonal variations were not statistically significant for all the geochemical parameters, whereas significant spatial variations were observed with lower values at sandy stations, suggesting that the texture of the sediments is the main factor influencing the sediment geochemistry. Significant inter-relations between the geochemical parameters also suggest a common control mechanism. Based on these geochemical characteristics, the study region can be effectively categorized into two distinct zones, viz. (1) erosion and transportation and (2) deposition zones.     

DDT in fish from the Bulgarian region of the Black Sea

In spite of a worldwide reduction in the utilization of organochlorine pesticides (OCPs), they are still a problem for the aquatic environment and human health. The Black Sea is still being polluted with persistent chemicals, including OCPs. Aquatic organisms (sprat, scad, bluefish, shad, belted bonito, goby, and black mussel) with different feeding behaviours were sampled on a seasonal basis from the Bulgarian region of the Black Sea, and the concentrations of 13 OCP residues were determined. Although many of the OCPs were not detected in the samples, in all samples 1,1,1-trichloro-2,2-bis(4-chlorophenyl) ethane (DDT) was present mainly in the form of its metabolites 1,1-dichloro-2,2-bis(4-chlorophenyl) ethane (DDD) and 1,1-dichloro-2,2-bis(4-chlorophenyl) ethylene (DDE). Only about 12% of the total DDT was present as the parent compound pp-DDT, which suggests that it was not being used recently in the region. The total DDT concentrations were generally below 150 μg kg^-1 fresh weight, but higher levels—up to 354 μg kg^-1 fresh weight—were also measured for fish species with a high fat content. Between-species differences were observed, even when the concentrations were presented on a fat-level basis. DDT concentrations did not show any significant changes over the 2-yr sampling period. Fish sampled in the northern areas of the Bulgarian Black Sea coast seemed to contain higher DDT levels than those from the southern areas, suggesting a major (historical) influence of the Danube River. For permanent monitoring purposes, the utility of Black Sea gobies and scad should be considered.