PARENT SESSION
Poster Session #50: Climate Change.
Thursday, August 8. Presentation from 8:00 AM to 9:30 AM. Exhibit Hall B & C, TCC

Climate control of annual plant-shrub coexistence.

Sternberg, Marcelo^*,1, Holzapfel, Claus¹, PARAG, HADAS², TIELBRGER, KATJA², KIGEL, JAIME³, ¹ Tel Aviv University, Tel Aviv, Israel² University of Potsdam, Potsdam, Germany³ Hebrew University of Jerusalem, Rehovot, Israel

ABSTRACT- Annual plants of semi-arid and arid areas are often closely associated with shrubs. The degree of association largely depends on the balance of positive and negative effects between these different plant life-forms ranging from interference to facilitation. This interaction balance is expected to shift with changing climatical conditions as positive interactions are predicted to become more important with increasing aridity. Here we describe production, diversity and richness, and soil seed bank characteristics of annual plant communities in four contrasting sites along a steep Mediterranean to desert gradient in Israel: a humid Mediterranean, a Mediterranean, a semi-desert, and a desert site. Annual biomass and diversity in open patches between shrubs increases from the humid Mediterranean sites to the Mediterranean site and decreases again towards the more arid sites. Annual production and diversity in association with shrubs (under shrub canopies) peaks in the semi-desert, while lower production and diversity was found on both extreme ends of the gradient. This pattern suggests that in different parts of the gradient contrasting interaction types are shaping the association of annuals with shrubs. This study is part of a large-scale climate change field experiment. We are currently experimentally testing whether climate change (e.g., increase and decrease in rainfall amounts) will shift shrub-annual associations in a similar pattern as observed in the present gradient study. Such information is essential to model impending effects of global climate change on complex species interactions, yet is currently still very scarce. The future dynamics of coexisting species can be only predicted based on such experimental data.

KEY WORDS: climate change