Soil carbon content along a rainfall gradient and inhibition of germination: a potential mechanism for regulating distribution of Plantago coronopus

The distribution of plant species in desert landscapes may be affected by inhibition of seed germination by factors in the soil. We tested the inhibition of Plantago coronopus seed germination on cyanobacterial soil crusts under laboratory conditions. Samples were collected from 10 locations along a rainfall gradient in the Negev Desert, Israel and soil crust and soil samples were collected from porcupine diggings in one location. We hypothesized that germination inhibition varies along this gradient as well as at a particular location mainly due to soil carbon content. We tested the hypothesis that soil carbon content has the same inhibition effect at both local and regional scales. There were strong negative relationships between germination and soil carbon content suggesting that this variable is at least a strong predictor of germination success for P. coronopus in Negev landscapes. Germination inhibition and its control by soil carbon content, may be an important influence on the distribution and dominance of plant species in this region.