Marcelo Sternberg's homepage

Edwin Lebrija-Trejos, PhD

Postdoctoral Fellow

Since my BSc. studies, I have been interested in plant community ecology, nature conservation, and resource management. Awareness of the impact of human activities on nature’s functioning is fortunately on the rise, but much is to be done from the scientific front to understand and face the challenges imposed by human-driven ecosystem changes.
Currently I hold a Post-doctoral position within the GLOWA Jordan River project - Phase III (www.glowa-jordanriver.de), a multidisciplinary and international research project dealing with the impact of global change on water resources.
The general objective of Phase III and the postdoctoral research is to integrate the results from different disciplines and participants into coherent scientific products that will support theoretically, and help to validate, predictive models for the response of natural plant communities to climate and land use changes.

e-mail: elebrija@post.tau.ac.il

Professional Education:

BSc Biology (Hons.), Facultad de Ciencias, Universidad Nacional Autónoma de México, 1995-2000.
MSc Forest and Nature Conservation (Hons.), Wageningen University, 2002-2004.
PhD Product Ecology & Resource Conservation, Forest Ecology and Forest Management Group, Wageningen University, 2004 – 2009.

http://www.fem.wur.nl/UK/Staff/PhD+students/trejos/
http://www.fem.wur.nl/UK/Research/Theme+1/trejos/

Publications:

Lebrija Trejos, E. 2001. Composición y estructura de la vegetación ribereña de la región de Nizanda, Oaxaca, México. Biology thesis, Universidad Nacional Autónoma de México
Lebrija Trejos, E. 2006. Secondary succession in a tropical dry forest of Southern Mexico. MSc thesis Wageningen University.
Lebrija-Trejos, E., F. Bongers, E. A. Pérez-García and J. A. Meave. 2008. Successional change and resilience of a very dry tropical deciduous forest following shifting agriculture. Biotropica 40: 422-431.
Brienen, R. J. W., E. Lebrija-Trejos, M. van Breugel, E. A. Pérez-García, F. Bongers, J. A. Meave and M. Martínez-Ramos. 2009. The potential of tree rings for the study of forest succession in southern Mexico. Biotropica 41:186-195.
Lebrija-Trejos, E., E. A. Pérez-García, J.A. Meave, F. Bongers and L. Poorter. Functional traits and environmental filtering drive community assembly in a species-rich tropical system (Ecology, in press).
Pérez-García, E. A., J. A. Meave, J. L. Villaseñor, J. A. Gallardo-Cruz and E. Lebrija-Trejos. Vegetation heterogeneity and life-strategy diversity in the flora of the heterogeneous landscape of Nizanda, Oaxaca, Mexico (submitted to Folia Geobotanica).
Brienen, R. J. W., E. Lebrija-Trejos, P. A. Zuidema and M. Martínez-Ramos. Rainfall and ENSO sensitivity of a tropical dry forest tree indicate future growth decreases due to climate change (submitted to Global Change Biology).
Lebrija-Trejos, E., E. A. Pérez-García, J.A. Meave, L. Poorter and F. Bongers. Community Dynamics of a Secondary Tropical Dry Forest: successional pathways and variability (in prep.).
Lebrija-Trejos, E., E. A. Pérez-García, J.A. Meave, L. Poorter and F. Bongers. Successional and Seasonal Changes in the Abiotic Environment of a Tropical Dry Forest (in prep.).

Carly Golodets

PhD Student

Throughout Europe and the Mediterranean Basin, agricultural lands have been abandoned, mainly for economic reasons. Some of these lands were managed as controlled grazing systems, supporting sheep, goats and/or cattle. The change in land use from grazing to natural vegetation raises many pertinent research questions relating to ecosystem functioning and management. My PhD examines the changes in vegetation composition and dominant plant traits resulting from land abandonment, and how these changes affect ecosystem functioning, as expressed via 1) primary productivity and 2) litter decomposition. The research is being carried out at the Karei Deshe experimental farm in the Upper Galilee, which is grazed by cattle under a controlled grazing system. I measured biomass production and several functional plant traits (leaf and seed characteristics, and whole plant traits), and conducted an experiment on litter decomposition, in both grazed and ungrazed plots. Differences in vegetation between treatments are determined largely by changes in dominance of the common species, as opposed to presence/absence. Therefore I have found that indices which take account of the differences in the proportional representation of species are able to reflect changes in species composition far more effectively than those based on presence/absence. For example, community-level trait values (weighted by species biomass) instead of species-level average trait values, or the Shannon diversity index (based on plant biomass) instead of species richness.

Email: adonis@agri.huji.ac.il

Joint supervision with Prof. Jaime Kigel, The Hebrew University of Jerusalem

Publications:

Golodets, C., Sternberg, M. and Kigel, J. (2009). A community-level test of the Leaf-Height-Seed ecology strategy scheme in relation to grazing conditions. Journal of Vegetation Science 20: 392-402
Golodets, C., Sternberg, M. and Kigel, J. (2008). A community-level test of the L-H-S ecology strategy scheme, and the link to ecosystem processes. In: Proceedings of the Thirty-Sixth Meeting of the Israel Society of Ecology and Environmental Quality Sciences (Iseeqs). Israel Journal of Ecology and Evolution 53(2): 257-278.
Golodets, C., Kigel, J. and Sternberg, M. (2009). Recovery of plant species composition and ecosystem function after cessation of grazing in a Mediterranean grassland. Plant & Soil (in press) DOI 10.1007/s11104-009-0164-1
Golodets, C., Sternberg, M. and Kigel, J. Diversity partitioning in a grazed Mediterranean grassland (in prep.)

Or-Leyl Har-Edom

PhD Student

Email: adonis@agri.huji.ac.il

Tzofnat Gal

MSc Student

I am interested in forest management and the combination of fungi and litter decomposition, and the associated soil properties. Factors that may affect the resilience capacity of the forest ecosystem following a forest fire are the removal of natural and planted vegetation, plant litter and dead wood material, soil exposure, run-off and reduction in soil organic matter. Previous studies have confirmed the use of wood chips can be used as covering agents to reduce soil erosion and improve the hydrological regime regulation. Therefore, this research focuses on the use of local fungi species (Pleurotus pulmonarius and Pleurotus ostreatus) to accelerate wood decomposition processes following a fire in a planted forest in order to prevent soil degradation and improve soil characteristics. In addition, the use of fungi has the potential to enhance nutrients cycling in soil while preventing soil erosion and run-off. The aim of this research is to optimize the use of wood chips by returning the woody debris material to the forest and by preventing soil degradation and consequent damage to potential vegetation growth. Understandings of the mechanisms and patterns involved in fungi decomposition processes of burnt trees and woody chips are of crucial importance for the sustainable management of forests in our region.

Joint supervision with Dr. Gil Eshel, The Soil Erosion Research Station, Ministry of Agriculture

Email: tzofi82@gmail.com

David Lifschitz

MSc Student

My research aims to quantitatively estimate the effects of soil cultivation practices (conventional tillage vs. no tillage) and climatic conditions on carbon sequestration (organic and inorganic) in wheat fields at arid and semiarid calcareous soils. We monitor soil CO2 partial pressures profiles up to a depth of two meters, and soil CO2 fluxes, as measures of root and microbial respiration. Furthermore we study soil organic and inorganic carbon changes to estimate the soil carbon cycle and its influence on the atmosphere carbon balance exchange. The research takes place in a long-term (over 30 years) experimental wheat field at the Gilat research station in the northern Negev (arid area, with mean annual rainfall of 220 mm). Four different cultivation practices are studied: 1) conventional tillage and fertilized, 2) conventional tillage non-fertilized, 3) no tillage fertilized and 4) no tillage non-fertilized. This study site is compared to a more mesic region (Bitzaron) in the southern coastal plain of Israel. This area is semiarid area, with mean annual rainfall of 450 mm and under standard commercial practices where conventional tillage and fertilization is applied.

Joint supervision with Dr. Gil Eshel, The Soil Erosion Research Station, Ministry of Agriculture

Email: davids_bar@hotmail.com

Assaf Inbar

MSc Student

Research Interests Effects of forest vegetation on soil in arid and semi arid regions Effects of forest fire on soil properties Soil amendments as method of stabilizing forest soils after wildfires Regeneration of forest natural flora after wildfires Current research Forest fires are a major environmental problem in the Mediterranean region because it implies the loss of vegetation cover, changes in biodiversity and a potential increase of soil erosion. These processes lead to the loss of soil nutrients, and consequently affect the functioning of the ecosystem. Moreover, it can lead to soil desertification. The current research focuses on the addition of synthetic polymers to prevent soil erosion and to stabilize soil structure. The combination of these two processes will potentially favor a faster recovery of the vegetation structure. The outcome of this study may provide important tools for forest fire management.

Joint supervision with Dr. Marcos Lado and Meni Ben-Hur, Agricultural Research Organization, The Volcani Center

Email: asinbar@gmail.com

Former Lab Members

Yuval Sapir, PhD

Porter Research Fellow

I am interested in processes at the interface of ecology, evolution and genetics. My research covers topics in ecological determinants of evolutionary processes, as well as the genetics of ecological adaptations. My main focus is on flowering plants and their interactions with biotic and a-biotic conditions. Currently I have two main projects. In one project, I am studying the pollination network associated with the Royal Irises (Iris sect. Oncocyclus) within the context of fragmentation and habitat destruction in the coastal plains of Israel. This study, funded by the Israeli NSF, is also looking at plant and bee biodiversity associated with the fragmentation of the natural habitat. This research could be useful both as an indicator for the conservation status for each fragmented habitat, as well as an explanatory variable for the functioning of the pollination network. I am also studying the scale and extent of cross-fertilization among Iris plants within and among populations in order to understand the balance between the mating system and local adaptation in an attempt to determine the process of speciation. In a second project I am studying possible evolutionary consequences of climate changes. Rapid change in the amount of precipitation in the Mediterranean and semi-arid climate regions may alter the selection exerted on plants, thereby affecting evolutionary trajectories. I am measuring phenotypic selection exerted on plants under experimental increase/decrease rain regimes in the Mediterranean and semi-arid climatic zones in Israel. These measurements, performed in both common garden and in the wild, are accompanied by a gene-expression study in order to identify the genes and processes most affected by the selection.

Email: sapiry@post.tau.ac.il

Representative publications:

Y. Sapir (2009) Pollination genetics: Using molecular genetic underlying floral traits to study pollination ecology in an evolutionary context. Israel Journal of Plant Sciences (accepted). Baack, E. J., Y. Sapir, M. A. Chapman, J. M. Burke, and L. H. Rieseberg (2008) Selection on domestication traits and QTLs in crop-wild sunflower hybrids. Molecular Ecology 17:666-677. Sapir, Y., M. L. Moody, L. C. Brouillette, L. A. Donovan, and L. H. Rieseberg (2007) Patterns of genetic variation and heterozygosity and candidate genes for ecological divergence in a homoploid hybrid sunflower, Helianthus anomalus. Molecular Ecology 16: 5017-5029. Sapir, Y., A. Shmida and G. Ne’eman (2006) Morning floral heat as reward to the pollinators of the Oncocyclus irises. Oecologia. 147:53-59. Sapir, Y., A. Shmida and G. Ne’eman (2005) Pollination of the Oncocyclus irises (Iris: Iridaceae) by night-sheltering male bees. Plant Biology. 7(4):417-424. Frumkin, R., A. Shmida, Y. Sapir, O. Fragman-Sapir and N. Levin (2004) Extinct plant species of Israel. pp. 41-43 in: Frumkin, R., Khenin, D. and A. Idelman (eds.) Vital Signs 2003 – Israel (WorldWatch Institute). Heschel Center, Tel-Aviv. Sapir, Y., A. Shmida and O. Fragman (2003) Constructing Red Numbers for endangered plant species - Israeli flora as a test case. Journal for Nature conservation 11(2):91-108.

Miguel J. Schwartz, PhD

Postdoctoral Fellow

NSF International Research Fellowship Program George S. Wise Faculty of Life Science, Tel Aviv University & Nicholas School of the Environment, Duke University

Current work Plant invasions and species range shifts in the face of climate change: An experimental and modeling study in Mediterranean ecosystems. Climate change is altering natural ecosystems in diverse ways. Shifts in species ranges and biological invasions are two of the most consequential of these impacts. These processes are associated with regional reductions in biodiversity, altered ecosystem function and reorganized species interactions. Because the mechanisms of species range shifts and exotic species invasions share common characteristics we are using an experimental and modeling framework that allow us to study both in a highly diverse ecosystem. Understanding the potential of species (be they exotics or immigrants from a neighboring region) to invade natural communities is key to predicting species, community, and ecosystem changes in a changing future. The Mediterranean basin, a biological hotspot, lies at the border between temperate and arid regions. Regional climate models indicate a significant reduction in precipitation with unknown consequences for natural systems. The main question we ask is: what might plant communities look like, given this dramatic climatic change.

Email: mjs21@duke.edu

Education:

Ph.D. Ecology, Duke University (2002 – 2007) Dissertation: Climactic changes over decadal and century scales in the North Carolina Piedmont Advisor: Norm Christensen Coursework: Bayesian predictive modeling, Time series statistics, Spatial Ecology & Spatial statistics, Geographical Information Systems, Ecological Data and Theory, Environmental law & policy B.Sc. Biology, Cornell University (1994 – 1998)

Recent grants and awards:

NSF IRFP Post Doctoral Fellowship (2007 – 2009) DISCCRS IV participant (2008) James B. Duke Graduate Fellowship (2002 – 2006) F.K. Weyerhaeuser Forest Fellowship (2005 – 2006) National Science Foundation Fellowship (2002 – 2005) Center for Tropical Conservation Research Grant (2004) Garden Club of America Research Grant (2003) Sigma Xi Grant-in-Aid of Research (2002)

Danny Harel

PhD Student

My main research interest focuses on the way annuals plant species cope with climatic variability, especially during the germination process. The germination process is a critical event in plants life, particularly for annuals occupying regions with high climatic variability combined with unpredictable precipitation. In order to increase fitness between years and reduce risks during germination, annual species have developed bet-hedging strategies. These strategies include syndromes of life traits such as seed dormancy, seed mass and dispersal. Theoretical models predict that along climatic gradients, with increasing climatic variability, the optimal strategy will consist of increasing seed dormancy and seed size. In addition, the importance of dispersal will reach its highest point at the intermediate part of the gradient. The aims of the present study are to define and quantify germination strategies used by annual species along the North-South rainfall gradient in Israel and to confront empirical data with the theoretical models. In contrast to the predictions of theoretical models, our results show the opposite effect of climatic variability and seed characteristics. Specifically, with the increase of climatic variability seed weight is decreasing and seed germination rates are increasing. In addition no significant difference was found in seed dispersal abilities rates along the climatic gradient.

Email: harel_danny@yahoo.com

Ranit Kirschenbaum

PhD Student

The encroachment of woody species in Mediterranean forests into open habitats has created concern regarding loss of biodiversity in herbaceous communities and cascading effects on other trophic levels. The patterns of biodiversity in relation to change in heterogeneity have previously been examined in these ecosystems, yet the mechanisms have yet to be defined. My research focuses, however, on experimental manipulation of spatial heterogeneity to determine the mechanisms influencing resources exploitation that result in the dominance of woody vegetation. Our hypothesis states that in the absence of disturbance, woody cover will increase, affecting resources availability to other components of the ecosystem. Alternatively, in the incidence of disturbance, the removal of the woody vegetation will increase spatial heterogeneity through the release of resources thus allowing higher biodiversity and ecosystem stability. This knowledge will be reflected in different landscapes formations that will support conservation strategies and adaptive management for natural Mediterranean forests.

Email: ranitkir@post.tau.ac.il

Orly Perry

MSc Student

The aim of this research is to examine the natural regeneration characteristics of a planted Mediterranean pine forest following fire and the effects of salvage logging operations on the renewal of natural vegetation. Salvage logging of burned forest stands is widely used to reduce economic losses following fire and assist ecosystem recovery by resetting the successional clock to zero. However, assumptions that this operation has no negative effect on forest systems have been questioned. The decision of whether to salvage include the assumption that naturally disturbed areas have: a) limited value for biota, b) that damaged trees will attract insects that will attack adjacent undisturbed stands and, c) that dead trees create abundant fuel and increased fire risk with the consequent threat to public safety. Nevertheless, salvage logging creates a major disturbance in the forest due to the dragging of burnt trees and heavy machinery used that may cause significant changes in the area. These disturbances include increase in the soil density, physical damage to emerging seedlings and exposure of soil to rain and run-off. The extraction of logs reduces the availability of organic matter to the animals and vegetation, therefore resulting in soil impoverishment. The goal of the research is to determine the effects of salvage logging on the natural regeneration of planted pines and the natural vegetation.

Email: orlyperry1@gmail.com

r10 - 02 Dec 2009 - 11:53:29 - IdoGan

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