Richard K. Kobe

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To investigate effects of green-leaf nutrient status on senesced-leaf nutrient concentrations and resorption efficiency, we developed a database of nitrogen (N) and phosphorus (P) concentrations in green and senesced leaves from 92 published studies. We fit power functions (i.e., [nutrient]sen 5 A [nutrient] ) separately for N and P. The database gr(More)
We examined interspecific and intraspecific variation in tree seedling survival as a function of allocation to carbohydrate reserves and structural root biomass. We predicted that allocation to carbohydrate reserves would vary as a function of the phenology of shoot growth, because of a hypothesized tradeoff between aboveground growth and carbohydrate(More)
To assess potential forest compositional responses to exchangeable soil calcium (Caexch) and aluminum (Alexch), we characterized light-dependent growth and mortality of tree seedlings under amendments of CaCl2 and AlCl3 at Hubbard Brook Experimental Forest (HBEF), New Hampshire, U.S.A. Seedlings of Acer saccharum Marsh., Fagus grandifolia Ehrh., Betula(More)
Under optimal partitioning theory (OPT), plants preferentially allocate biomass to acquire the resource that most limits growth. Within this framework, higher root mass under low nutrients is often assumed to reflect an allocation response to build more absorptive surface. However, higher root mass also could result from increased storage of total(More)
We have developed models of sapling mortality for the eight dominant tree species of northwestern British Columbia in order to better understand forest community dynamics and succession in this important forest region. The species-specific models characterize an individual’s probability of mortality as a function of recent growth (a surrogate for(More)
Interspecific differences in sapling growth responses to soil resources could influence species distributions across soil resource gradients. I calibrated models of radial growth as a function of light intensity and landscape-level variation in soil water and foliar N for saplings of four canopy tree species, which differ in adult distributions across soil(More)
Density-dependent seedling mortality could increase with a species relative abundance, thereby promoting species coexistence. Differences among species in light-dependent mortality also could enhance coexistence via resource partitioning. These compatible ideas rarely have been considered simultaneously. We developed models of mortality as functions of(More)
Tree species can differ in their responses to resource availability during the critical phase of establishment, which could influence forest dynamics. In Mediterranean forests, most of the attention has focused on the effects of shade and summer drought on seedling survival, but little is known about the effect of autumn to spring rains on earlier stages of(More)
A negative feedback between local abundance and natural enemies could contribute to maintaining tree species diversity by constraining population growth of common species. Soil pathogens could be an important mechanism of such noncompetitive distance and density-dependent (NCDD) mortality, but susceptibility to local pathogens may be ameliorated by a life(More)
I. M. Pérez-Ramos (, I. R. Urbieta, and T. Marañón, IRNAS, CSIC, P.O. Box 1052, ES-41080 Sevilla, Spain. Present address for IMPR: Centre d’Ecologie Fonctionnelle et Evolutive, CNRS, 1919 Route de Mende, FR-34293 Montpellier 5, France. M. A. Zavala and present address for IRU: Depto de Ecologı́a, Edificio de Ciencias, Univ.(More)