The study of species coexistence and community assembly has been a hot topic in ecology for decades. Disentangling the hierarchical role of abiotic and biotic filters is crucial to understand community assembly processes. The most critical environmental factor in semi-arid environments is known to be water availability, and perennials are usually described as nurses that create milder local con...

Seasonal changes in day length are used by plants and animals to synchronize annual rhythms in reproduction, physiology, and behavior to the environment. Increasing day length during spring causes sudden changes in the mammalian reproductive system once the critical photoperiod is reached. The molecular mechanism behind this switch is now quickly being elucidated.

We introduce a theoretical framework that predicts the optimum planting density and maximal yield for an annual crop plant. Two critical parameters determine the trajectory of plant growth and the optimal density, N(opt), where canopies of growing plants just come into contact, and competition: (i) maximal size at maturity, M(max), which differs among varieties due to artificial selection for d...

Previous studies have examined the decoupling of C, N, and P under rapid changes in climate. While this may occur in different environment types, such climactic changes have been reported over short distances in mountainous terrain. We hypothesized that the decoupling of C, N, and P could also occur in response to increases in altitude. We sampled soil and plants from Mount Gongga, Sichuan Prov...

Fractal symmetry is symmetry across scale. If one looks at a branch of a tree its branching pattern is reminiscent of the tree as a whole. Plants exhibit a number of different symmetries, including bilateral, rotational, translational, and fractal; deviations from each of these types has been associated with organisms developing in stressful environments. Here, we explore the utilization and me...

This article presents some statistical methods for estimating the parameters of a population dynamics model for annual plants. The model takes account of reproduction, immigration, seed survival in a seed bank, and plant growth. The data consist of the number of plants in several developmental stages that were measured in a number of populations for a few consecutive years; they are incomplete ...

The paper estimates the effect of SO2 pollution on infant mortality in Germany, 1985-2003. To avoid endogeneity problems, I exploit the natural experiment created by the mandated desulfurization at power plants and power plants' location and prevailing wind directions, which together determine treatment intensity for counties. Estimates translate into an elasticity of 0.07-0.13 and the observed...

In Yokkaichi-city, where power stations, oil refining and related chemical plants exist, growing number of cases of asthmatic patients has been reported since these plants were put in operation in 1955. At Isozu, where air pollution is most severe, incidence of asthma reached up to 2.5% of total population in 1964. In whole Yokkaichi-city, annual average of sulphur dioxide level by lead peroxid...

Lolium rigidum (annual or rigid ryegrass) is a widespread annual weed in cropping systems of southern Australia, and herbicide resistance in L. rigidum is a common problem in this region. In 2010, a random survey was conducted across the grain belt of Western Australia to determine the frequency of herbicide-resistant L. rigidum populations and to compare this with the results of previous surve...