Patch size and shape and their relationship with tree and shrub species richness

Se relacionó el tamaño y forma de 10 fragmentos de bosque nativo con la riqueza de especies de árboles y arbustos en la precordillera costera de la provincia de Osorno, sur de Chile. Se ajustaron cuatro modelos de regresión (lineal, logarítmico, exponencial y potencial), entre el tamaño de fragmentos (área = x) y la riqueza de especies de árboles y arbustos (número de especies = y). Se cuantificó la forma de los fragmentos a través de tres índices (índice de diversidad de Patton, índice de compactación y dimensión fractal), y se obtuvieron las correlaciones parciales entre el área y la riqueza de especies controlando el efecto recíproco del área y el perímetro. Los resultados permitieron concluir que: la riqueza de especies tiende a aumentar significativamente con el tamaño del fragmento, relación que fue explicada por los cuatro modelos. No obstante, el mejor ajuste se logró con el modelo de regresión lineal simple, con un R2 de 65,1% (y = 5,9 + 0,15x); las formas de los fragmentos fueron en general complejas asemejándose a la de objetos fractales, y el área fue el factor que explicó de modo más consistente la riqueza de especies (rxy.z = 0,699); la forma no tuvo un efecto significativo en las variaciones de riqueza de especies de árboles y arbustos

Comparative demography and diversity of small mammals in precordilleran temperate rainforests of Southern Chile

Small mammals were studied in two southern Chilean temperate rainforests in the precordillean Andes during 2 low-rainfall years following the 1982 El Niño event. Forests had somewhat different levels of canopy, shrub, and herbaceous cover, and species richness of trees but most of the same plants. Most captures were of four sigmodontine rodents, Akodon olivaceus, Abrothrix longipilis, Abrothrix sanborni, and Oligoryzomys longicaudatus; five other species and a putative hybrid were recorded. Maximum numbers were in January-July (late summer to winter) and lower numbers in August-December (late winter to early summer). All species had seasonal reproduction in September-April (spring to autumn). A. olivaceus and A. longipilis generally were long-lived, whereas survival rates were low for O. longicaudatus. Responses after the 1982 El Niño were small, and some populations increased during 1984. Populations of A. olivaceus fluctuated more than those of A. longipilis; those of A. sanborni were low and O. longicaudatus was sporadic and irruptive. Lower-elevational Chilean and precordilleran Argentine forests have similar species composition, but differences in demography and dominance of the former by more widespread, omnivorous A. olivaceus, animalivorous-fungivorous Abrothrix, and granivorous O. longicaudatus. Opportunities for immigration may explain greater homogeneity of populations of small mammals in Chilean rainforests relative to Argentine ones. Although responses to El Niño and subsequent droughts were weak, flowering episodes of bamboo (Chusquea) can have strong effects due to increased availability of food

Tree and shrub diversity in native rainforest fragments in southern Chile

We sampled the diversity of trees and shrubs, and built the rarefaction and accumulation species curve in 10 native forest fragments in southern Chile. Results indicated that: (1) there were 23 species in all sampled fragments, (2) species richness increased significantly with fragment size, (3) all fragments require a minimal sampling from 40 to 170 individuals to reach the maximum theoretical species richness, and (4) sampling richness was greater than that theoretically expected (20 species)

The conservation status of raptors in Chile

We classified 30 species of raptors in Chile using the technique proposed by Reca et al. (1994) and the conservation categories proposed by Grigera and Úbeda (2000). The results were obtained by means of an index that considers 12 variables that represent factors of importance for the survival or the conservation of the species. Eight species (27%) were classified in the category of maximum priority, nine (30%) in the special attention category, and 13 (43%) in the no priority category. Strix rufipes and Buteo exsul were considered with the highest priority of conservation, and together with Accipiter chilensis, Buteo albigula, Buteo ventralis, Phalcoboenus australis, Vultur gryphus, and Phalcoboenus albogularis conform the category of maximum priority conservation. Diurnal raptors (Falconiformes) need a greater conservation priority than nocturnal raptors (Strigiformes). At the family level, Accipitridae had the highest species richness and also showed major conservation problems. We concluded that the technique is a useful tool with simple application that allows orienting the public conservation decisions on this taxonomic group

Lifetime distributions in the methods of non-equilibrium statistical operator and superstatistics

A family of non-equilibrium statistical operators is introduced which differ by the system age distribution over which the quasi-equilibrium (relevant) distribution is averaged. To describe the nonequilibrium states of a system we introduce a new thermodynamic parameter - the lifetime of a system. Superstatistics, introduced in works of Beck and Cohen [Physica A \textbf{322}, (2003), 267] as fluctuating quantities of intensive thermodynamical parameters, are obtained from the statistical distribution of lifetime (random time to the system degeneracy) considered as a thermodynamical parameter. It is suggested to set the mixing distribution of the fluctuating parameter in the superstatistics theory in the form of the piecewise continuous functions. The distribution of lifetime in such systems has different form on the different stages of evolution of the system. The account of the past stages of the evolution of a system can have a substantial impact on the non-equilibrium behaviour of the system in a present time moment.Comment: 18 page

Exclusion limits on the WIMP-nucleon cross-section from the Cryogenic Dark Matter Search

The Cryogenic Dark Matter Search (CDMS) employs low-temperature Ge and Si detectors to search for Weakly Interacting Massive Particles (WIMPs) via their elastic-scattering interactions with nuclei while discriminating against interactions of background particles. For recoil energies above 10 keV, events due to background photons are rejected with >99.9% efficiency, and surface events are rejected with >95% efficiency. The estimate of the background due to neutrons is based primarily on the observation of multiple-scatter events that should all be neutrons. Data selection is determined primarily by examining calibration data and vetoed events. Resulting efficiencies should be accurate to about 10%. Results of CDMS data from 1998 and 1999 with a relaxed fiducial-volume cut (resulting in 15.8 kg-days exposure on Ge) are consistent with an earlier analysis with a more restrictive fiducial-volume cut. Twenty-three WIMP candidate events are observed, but these events are consistent with a background from neutrons in all ways tested. Resulting limits on the spin-independent WIMP-nucleon elastic-scattering cross-section exclude unexplored parameter space for WIMPs with masses between 10-70 GeV c^{-2}. These limits border, but do not exclude, parameter space allowed by supersymmetry models and accelerator constraints. Results are compatible with some regions reported as allowed at 3-sigma by the annual-modulation measurement of the DAMA collaboration. However, under the assumptions of standard WIMP interactions and a standard halo, the results are incompatible with the DAMA most likely value at >99.9% CL, and are incompatible with the model-independent annual-modulation signal of DAMA at 99.99% CL in the asymptotic limit.Comment: 40 pages, 49 figures (4 in color), submitted to Phys. Rev. D; v.2:clarified conclusions, added content and references based on referee's and readers' comments; v.3: clarified introductory sections, added figure based on referee's comment

Farming with crops and rocks to address global climate, food and soil security

The magnitude of future climate change could be moderated by immediately reducing the amount of CO 2 entering the atmosphere as a result of energy generation and by adopting strategies that actively remove CO 2 from it. Biogeochemical improvement of soils by adding crushed, fast-reacting silicate rocks to croplands is one such CO 2 -removal strategy. This approach has the potential to improve crop production, increase protection from pests and diseases, and restore soil fertility and structure. Managed croplands worldwide are already equipped for frequent rock dust additions to soils, making rapid adoption at scale feasible, and the potential benefits could generate financial incentives for widespread adoption in the agricultural sector. However, there are still obstacles to be surmounted. Audited field-scale assessments of the efficacy of CO 2 capture are urgently required together with detailed environmental monitoring. A cost-effective way to meet the rock requirements for CO 2 removal must be found, possibly involving the recycling of silicate waste materials. Finally, issues of public perception, trust and acceptance must also be addressed