| mediterranean climate effects. i. conifer water use across a sierra nevada ecotone. | xylem water potential of the midelevation conifers pinus jeffreyi, pinus lambertiana, abies concolor, and calocedrus decurrens, the higher elevation pinus monticola and abies magnifica, and co-occurring evergreen angiosperm shrubs, together with soil moisture under these plants, were monitored at three sites on the kern plateau in the southernmost sierra nevada range of california: site locations spanned the ecotone between the mid- and upper montane forests at elevations of 2230-2820 m. measure ... | 2001 | 11353716 |
| mediterranean climate effects. ii. conifer growth phenology across a sierra nevada ecotone. | growth and xylem water potential of the lower elevation conifers pinus jeffreyi and abies concolor and the higher elevation pinus monticola and abies magnifica were monitored in their montane mediterranean habitat of the southernmost sierra nevada mountains of california: measurements were made across the ecotone between the midmontane and upper montane forests and through light and heavy snowfall years. radial stem growth, averaging approximately 1.5 mm/yr, started 2 wk after snow melt, providi ... | 2001 | 11353717 |
| spatial elements of mortality risk in old-growth forests. | for many species of long-lived organisms, such as trees, survival appears to be the most critical vital rate affecting population persistence. however, methods commonly used to quantify tree death, such as relating tree mortality risk solely to diameter growth, almost certainly do not account for important spatial processes. our goal in this study was to detect and, if present, to quantify the relevance of such processes. for this purpose, we examined purely spatial aspects of mortality for four ... | 2008 | 18589538 |
| electronic properties and the quantum hall effect in bilayer graphene. | in this paper, i review the quantum hall effect (qhe) and far-infra red (fir) absorption properties of bilayer graphene in a strong magnetic field. this includes a derivation of the effective low-energy hamiltonian for this system and the consequences of this hamiltonian for the sequencing of the landau levels in the material: the form of this effective hamiltonian gives rise to the presence of a level with doubled degeneracy at zero energy. the effect of a potential difference between the layer ... | 2008 | 18024357 |
| species richness and stand stability in conifer forests of the sierra nevada. | theoretical and empirical studies have long suggested that stability and complexity are intimately related, but evidence from long-lived systems at large scales is lacking. stability can either be driven by complex species interactions, or it can be driven by the presence/absence and abundance of a species best able to perform a specific ecosystem function. we use 64 years of stand productivity measures in forest systems composed of four dominant conifer tree species to contrast the effect of sp ... | 2006 | 17168023 |
| high root concentration and uneven ectomycorrhizal diversity near sarcodes sanguinea (ericaceae): a cheater that stimulates its victims? | sarcodes sanguinea is a nonphotosynthetic mycoheterotrophic plant that obtains all of its fixed carbon from neighboring trees through a shared ectomycorrhizal fungus. we studied the spatial structuring of this tripartite symbiosis in a forest where sarcodes is abundant, and its only fungal and photosynthetic plant associates are rhizopogon ellenae and abies magnifica, respectively. we found disproportionately high concentrations of abies roots adjacent to sarcodes roots compared to the surroundi ... | 2000 | 11118414 |