The effect of plants on the abundance and distribution of soil resources

Ecologist tend to see soil resources as a control of vegetation structure and function, but the interaction between plants and soils has a more circular nature with plants having a very active role on soil resources abundance and distribution. As a central part of my dissertation, I am interested on how plant recycling rates and allocation and rooting depth patterns affect the abundance and distribution of soil nutrients and carbon. I approach this issue based on 1) existing data for soil profiles from all over the world, 2) simple simulation models, 3) direct observations of ecosystems that have experienced drastic vegetation changes in the last decades. This project is providing some clues about the potential use of soil profile data to infer aspects of vegetation functioning like nutrient limitation and allocation. In addition to soil nutrients and carbon, I am interested in the redistribution of soil water by plants (i.e. hydraulic lift). I conduct an experiment to evaluate the ability of plants to cope with incongruent distributions of water and nutrients through hydraulic lift.

Jobbágy EG and RB Jackson. The vertical distribution of soil organic carbon and its relation to climate and vegetation. Ecological Applications, in press   -abstract-

Jackson RB et al. Belowground consequences of vegetation change and its treatment in models. Ecological Applications, in press  -abstract-
 
 
 
 

Vegetation-climate relationships in the northern and southern hemispheres

Comparisons between hemispheres offer the possibility to test how organism that evolved independently adjusted to the same climatic constraints. I am particularly interested in the response of plant distributions to temperature. Recently I performed a global analysis of forest line distributions in mountain ranges from temperate areas of both hemispheres. After the key thermal variables that explain forest line elevation were established (mean annual temperature and seasonal thermal amplitude), no differences between hemispheres were found, suggesting a high degree of convergence. Previous work in this line focused on primary production controls, and C3/C4 grasses and shrub distributions and yielded similar results.

Jobbágy EG and RB Jackson. Global controls of forest line elevation in the northern and southern hemispheres. Global Ecology and Biogeography, in press  -abstract-

Paruelo JM, EG Jobbágy, OE Sala, WK Lauenroth and IC Burke. 1998. Functional and structural convergence of temperate grassland and shrubland ecosystems. Ecological Applications, 8:194-206  -abstract-
 
 
 
 

Ecology of the Patagonian steppe

Since 1991 I have been working on different aspects of the ecology of the arid grasslands of Patagonia. My main interest has been the understanding of net primary production (NPP) patterns and controls. At a regional scale I described the association between NPP and climate in space and time using satellite data. At a local scale I followed biomass dynamics and leaf and tiller demography to establish the role of climate on the NPP of the two dominant plant functional types, grasses and shrubs. On another line I studied how floristic composition and diversity respond to water availability at a local scale and to landscape configuration at a regional scale. I also worked on the characterization of the ecological regions of Patagonia.

Jobbágy EG, OE Sala, and JM Paruelo. Patterns and controls of primary production in the Patagonian steppe: A remote sensing approach. Ecology, in press  -abstract-

Jobbágy EG and OE Sala. Controls of grass and shrub production in the Patagonian steppe. Ecological Applications, in press  -abstract-

Paruelo JM, EG Jobbágy, and OE Sala. 1998. Biozones of Patagonia (Argentina). Ecología Austral 8:145-153  -abstract-

Paruelo JM, A Beltrán, EG Jobbágy, OE Sala, and RA Golluscio. 1998. The climate of Patagonia: General patterns and controls on biotic processes. Ecología Austral 8:85-101 -abstract-

Jobbágy EG, JM Paruelo and RJC León. 1996. Vegetation heterogeneity and diversity in flat and mountain landscapes of Patagonia (Argentina). Journal of Vegetation Science, 7:599-608   -abstract-

Schulze ED et al. 1996. Water availability, rooting depth, and vegetation zones along an aridity gradient in Patagonia. Oecologia, 108:503-511  -abstract-

Jobbágy EG, JM Paruelo and RJC León. 1995. Estimación de la precipitación a partir de la distancia a la cordillera en el noroeste de la Patagonia. Ecología Austral 5:47-53  -abstract-