Research

As ecologists, we are interested in the entire plant community, i.e., all the species found in a specific place (rather than a particular species). We seek to understand patterns of species diversity (e.g., number of species), trait distribution (e.g., the mean and variance in seed mass), and composition.To achieve this, we use an observational approach (going to the field or collecting big data), an experimental approach, and theoretical models. Here are examples of some topics we currently study:

How does disturbance affect plant communities?

Disturbances can increase or decrease diversity depending on many factors. Understanding these factors is a key aim in ecology and is crucial for present and future conservation efforts. We use experimental plant communities (mesocosms) to test the effects of initial composition (the sowing frequency of the different species) and timing of disturbance (early vs. late).

What is the global distribution of plant lifeforms?

Plants have many strategies to cope with the environment and with other organisms. Some species live a single year (annuals) while others live many years (perennials). Some species have long-lived hard tissues (woody species), and some don't (herbs). We aim to quantify the effects of climate and human disturbance on the prevalence of the different strategies on a global scale. So far, we have collected data on 67% of the species on earth!

How do trees interact with herbs?

Trees can facilitate or inhibit the growth of herbs. Similarly, they can increase or decrease plant diversity and change community composition. We are searching for general rules that can explain tree-herb interactions. We have several projects regarding the effects of trees (both native and non-native) on the herbs in their understory. The projects involve theory and field observation, and their outcomes are essential for managing natural communities.

How do feedbacks between plant and soil microbiomes determine the composition of plant communities?

Plants can promote a mutualistic microbiome that favors their growth (positive feedback) but can also enhance pathogens that inhibit growth (negative feedback). The interplay between positive and negative feedbacks has a significant role in determining the structure of plant communities. Understanding these feedbacks is one of the major frontiers of plant ecology.

Does history matter?

The classical view of ecosystems suggests that they are always attracted toward a single equilibrium (the balance of nature). Under such an assumption, the history of a system is not important because, under the same environment, the community composition will always reach the equilibrium state (without perturbation). However, an alternative view suggests that ecosystems are historical-contingent, i.e., under the same environmental conditions, communities can have a very different composition if they have a different history.

These two possibilities cannot be investigated in nature because the history of ecosystems is unknown. We, therefore, manipulate the history of experimental communities (initial frequencies or the order of sowing). We test whether communities with different histories converge over time (becoming more similar, indicating a single equilibrium) or not (indicating that history matters). This project's results are important for restoring the degraded system where we can manipulate the "history" (order of sowing of different species or sowing density).

What are the consequences of climate change to plant communities?

Nowadays, we know climate change is not simply an increase in temperature or a reduction in rainfall. Instead, a major effect of climate change is related to rainfall distribution over the growing season. In Israel, there is a significant trend of decline in the length of the growing season. We, therefore, investigate the consequences of the timing of drought during the rainy season on plant communities.