Paul E. Waggoner

Returning forests analyzed with the forest identity

Amid widespread reports of deforestation, some nations have nevertheless experienced transitions from deforestation to reforestation. In a causal relationship, the Forest Identity relates the carbon sequestered in forests to the changing variables of national or regional forest area, growing stock density per area, biomass per growing stock volume, and carbon concentration in the biomass. It quantifies the sources of change of a nations forests. The Identity also logically relates the quantitative impact on forest expanse of shifting timber harvest to regions and plantations where density grows faster. Among 50 nations with extensive forests reported in the Food and Agriculture Organizations comprehensive Global Forest Resources Assessment 2005, no nation where annual per capita gross domestic product exceeded

Economic benefits from research: an example from agriculture

4,600 had a negative rate of growing stock change. Using the Forest Identity and national data from the Assessment report, a single synoptic chart arrays the 50 nations with coordinates of the rates of change of basic variables, reveals both clusters of nations and outliers, and suggests trends in returning forests and their attributes. The Forest Identity also could serve as a tool for setting forest goals and illuminating how national policies accelerate or retard the forest transitions that are diffusing among nations.

Anticipating the frequency distribution of precipitation if climate change alters its mean

In this article we examine the economic benefits of the long history of public research in agriculture. Agricultural productivity continues to grow. Annual rates of return on research expenditure are of the order of 50 percent. Research oriented to science is profitable when associated with technological research. Decentralization, as in the system of state agricultural experiment stations and substations, has allowed close association of research oriented to science with that oriented to technology and to farming. The high rate of return shows that investment in public research in agriculture is too low. This is at least partially because research benefits spill over to other regions and to consumers, reducing the incentives for local support.

A National and International Analysis of Changing Forest Density

Abstract The relationship between the shape and dispersion of the frequency distributions of precipitation amounts and their means among present climates gives a clue as to how the probabilities of extremes will change if the mean changes. The distribution is limited at zero and, as the means decrease, the standard deviations decrease and the distributions become more skewed. The gamma distribution function fits these distributions from the nearly normal of annual amounts in humid climates to the skewed of monthly in arid ones. Its mean, M , is BG and variance, V , is B 2 G , where B is the scale and G the shape parameter. Among 660 cases of 12 monthly distributions at 55 diverse stations, the variance increased as M 1.3 ( r 2 =0.90), which specifies relationships between the mean and B and G . Thus, probabilities are specified by the mean and among 660 cases, 572 specified probabilities of amounts less than half the mean were not significantly different from observed. For precipitation more than three halves the mean, 653 were not significantly different from observed. The relationships among parameters specify a dimensionless elasticity or relative increase in the probability of extremes with a relative decrease in the mean. For amounts below a threshold, the elasticity is greater for lower thresholds and higher means, and it is often >1, signifying a relatively greater rise in the probability of extremes than a fall in the mean.

Lightening the tread of population on the land: American examples.

Like cities, forests grow by spreading out or by growing denser. Both inventories taken steadily by a single nation and other inventories gathered recently from many nations by the United Nations confirm the asynchronous effects of changing area and of density or volume per hectare. United States forests spread little after 1953, while growing density per hectare increased national volume and thus sequestered carbon. The 2010 United Nations appraisal of global forests during the briefer span of two decades after 1990 reveals a similar pattern: A slowing decline of area with growing volume means growing density in 68 nations encompassing 72% of reported global forest land and 68% of reported global carbon mass. To summarize, the nations were placed in 5 regions named for continents. During 1990–2010 national density grew unevenly, but nevertheless grew in all regions. Growing density was responsible for substantially increasing sequestered carbon in the European and North American regions, despite smaller changes in area. Density nudged upward in the African and South American regions as area loss outstripped the loss of carbon. For the Asian region, density grew in the first decade and fell slightly in the second as forest area expanded. The different courses of area and density disqualify area as a proxy for volume and carbon. Applying forestry methods traditionally used to measure timber volumes still offers a necessary route to measuring carbon stocks. With little expansion of forest area, managing for timber growth and density offered a way to increase carbon stocks.

Dematerialization: Variety, caution, and persistence

The authors search the past century for principles and trends influencing land use in the United States and contemplate the future when Americans might number an additional 100 million. Examples from American cities counties and states suggest that land covered by the built environment increases less than in proportion to population. For example despite the rising use of paper relative to gross national product the declining use of lumber combined with improved forestry kept the area of forest land fairly steady as population rose. Similarly rising yields and changing tastes have countered the impact of rising population and wealth on crop-land area. All told a lightening tread of Americans on the land in the next century could spare for nature over 90 million hectares an area equal to 100 times the size of Yellowstone National Park. (SUMMARY IN FRE AND SPA) (EXCERPT)

How gypsy moth eggs freeze

Dematerialization, represented by declining consumption per GDP of energy or of goods, offers some hope for rising environmental quality with development. The declining proportion of income spent on staples as affluence grows, which income elasticity <1.0 measures, makes dematerialization widespread. Further, as learning improves efficiency of resource use, the intensity of environmental impact per production of staples often declines. We observe that combinations of low income elasticity for staples and of learning by producers cause a variety of dematerializations and declining intensities of impact, from energy use and carbon emission to food consumption and fertilizer use, globally and in countries ranging from the United States and France to China, India, Brazil, and Indonesia. Because dematerialization and intensity of impact are ratios of parameters that may be variously defined and are sometimes difficult to estimate, their fluctuations must be interpreted cautiously. Nevertheless, substantial declining intensity of impact, and especially, dematerialization persisted between 1980 and 2006.

Calibration of a porometer in terms of diffusive resistance

Abstract Although eggs of the gypsy moth Lymantria dispar (L.) supercool, a steady and substantial portion freezes and dies at a steady temperature below −26°C. The rate of freezing at steady temperature is about 1% per min at −27°C and changes about tenfold per degree. The freezing of the eggs at varying temperature is predicted by integration of the rates observed at steady temperature.

The hatching of gypsy moth eggs, a phenological model

Abstract The rate of pressure drop in a convenient leaf-porometer is shown to be a simple function of several separable components of flow resistance. Those due to stomata are arrived at by measuring or estimating the others. Stomatal resistance is also calculated from viscous flow theory and the observed dimensions of sample stomata or their replicas. Measured and calculated values for barley agree moderately well, thus justifying the model used in calculation. With standard molecular diffusion theory, the same dimensions give the diffusive resistance of the stomata, which is the quantity of interest in transpiration or assimilation studies. With suitable averaging procedures to relate the properties of single pores to those of whole leaves, a simplified theoretical relation between viscous and diffusive resistance is found permitting conversion of porometer readings directly into diffusive resistances.

Comparison of simulated and actual evaporation from maize and soil in a lysimeter

Abstract The skewed course of hatching of gypsy moth eggs is represented by a mathematical model embodying the conception that the eggs begin at location 0 in development space and progress at a rate that is the reciprocal of the time when the first eggs hatch because they reach location 1 in space. During their progress, a daily fraction is delayed for a period and then progresses again from the location in space from which it was delayed. Theoretically, the course of hatching is represented by a Poisson function, with the usual mean replaced by the product of the daily fraction delayed and the time of first hatch. A time referred to the time of first hatch and adjusted for the period of delay replaces the usual number whose frequency is calculated. Skewness significantly exceeded the expected 0 of the Normal curve in 79% of 91 experiments at steady temperature, whereas it exceeded the expected skewness of the Poisson in only 35%. The times of first hatch and of delay and the daily fraction delayed changed in an orderly fashion from 12 to 33°C. In 43 experiments with changing temperature in the laboratory, the course of hatching was predicted by numerical integration of the parameters observed at steady temperature. The standard deviation of the difference between observation and prediction was 2 3 day for the time of first hatch and the mean time of individual hatches; it was 1 2 3 days-squared for the variance and 1 2 unit for the skewness. In six outdoor experiments from spring to autumn, the entire courses of hatching were predicted reasonably well, and the means were predicted more consistently than by a method of degree-days.