Indeed, distrubances can increase plant diversity. Biodiversity in general, not only phytodiversity. Disturbances can be perceived as a heterogenous environment providing available habitats, food and shelter and thus increasing the biodiversity.

Destructive processes lead to degradation of the original ecosystem and create a new one at the same time.  

Wiezik M., Wieziková A., Svitok, M., Vegetation structure, ecological stability, and low-disturbance regime of abandoned dry grasslands support specific ant assemblages in Central Slovakia. Tuexenia, 2011, 31, 301-315

I personally disagree with positive effects of disturbance, that often masks land clearing aims for making short term profits. The side effetcs like fragmentation and alien invasion modify the original equilibria and sinbioses and litter cycle are destryed. For grassland vegetation there could bepositive effects provided a level of intermediate disturbance. Soil erosion and water drainage are side effects. http://scholar.google.it/scholar_url?url=http://www.myxyz.org/phmurphy/dog/DisturbanceDiversityInvasion.pdf&hl=it&sa=X&scisig=AAGBfm1S-O_AgD7wIs2jnzG78DKWVH61eg&nossl=1&oi=scholarr&ved=0ahUKEwisg5rx98TMAhWDJhoKHRg-CiYQgAMIGygAMAA

Dear Abhishek Raj, Tomáš Lepeška, and Guido Bongi

Thank you very much for your guidance.

According to the intermediate disturbance hypothesis (IDH), plant diversity should be highest at intermediate levels of disturbance intensity (i.e. grazing). In addition, the dynamic equilibrium model (DEM) suggests that moderate grazing intensity should have positive effects on diversity in high-productivity systems and negative effects in low-productivity systems.

But, Dose high severity/intensity of disturbance lead to increase in diversity, too?

Does anyone know any reference or study in this regards.

Best regards

Reza

I would not say the effects of disturbances are only positive (positive for what? nature? human kind?). I completely agree that effects can have also very significant consequences on an original ecosystem. But isn´t resistivity and resiliance one of main ecosystem´s answers to the disturbances? E.g. natural ecosystems of Norway spruce do need disturbances for their evolution through patchiness with a small grain of mosaic. Thanks to disturbances (avalanches, nival erosion, water erosion,debris slides etc.) there is a huge diversity of spieces in (and not only) the Western Carpathians. Thanks to this multi-source and multidimensional heterogeneity the timberline was not closed, coherent, but it was a shifting mosaic of succession and forest-free area.

In 2002, in southern France,was a study in a protected area. To protect the reserve it was banned the grazing hay fields and it was observed a decrease from 210 to 130 plant taxa in 3-4 years. Protected area administration tried to explain the decline of plant diversity and they have reintroduced grazing. After 5-6 years the plant diversity increased again to over 200 taxa. By grazing some species that produce more seeds and dispersed in time are eaten by animals before all the seeds become mature a reasonable number of seed came matures  and do not become numerically dominant and  eliminate other species in competitive system.

How is "disturbance" defined? Is a wildfire a disturbance or is control/suppression of wildfire the disturbance. Is grazing a disturbance or the abandonment of a pasture (Iuliana Answer)?  And so on.

Is the disturbance a human intervention, a natural catastrophic invent, or both?

At what frequency, disturbance becomes part of the ecosystem?

Currently we are testing a published hypothesis on post-fire tree biodiversity of a fire. See also my project on RG

Article From monospecific to mixed forest after fire?: An early fore...

Disturbance can have a plethora of effects on plant diversity. The response depends upon multiple factors including forest type, forest canopy layer, and diversity index.

From the study that I conducted the effect of a pulse perturbation can be hierarchically influenced by background press perturbations.

Wayne

Disturbance facilitates the highest level of diversity when it occurs at intermediate levels of frequency as stated in the intermediate disturbance hypothesis. Terrestrial disturbances such as those that you mentioned (fire, grazing, etc.) allows for the clearing of land area and colonization of new species (as is the case for secondary succession). Too much and too little of disturbance can lead to low diversity. If disturbance occurs at a high frequency, the community is dominated by the good colonizers while low frequency allows for competitive exclusion. A textbook example of a study that may be of relevance to your question is one done by April Whicker and James Detling in 1988 wherein they proposed prairie dogs as an importance source of disturbance in prairies as their burrow systems created patches that allowed for new colonization of plants. Another animal that acts as a source of disturbance for plant communities may be pocket gophers. You may check this link for a related study:https://link.springer.com/article/10.1007%2FBF00324644?LI=true

Hope I answered your question! 

In early stages, different anthropic activities can increase the diversity of species. For example:

- discharge into a river  the water  industrial effluent  with a temperature of 10 degrees Celsius higher may change habitat conditions allowing the installation of more thermophilous species.

- Intake of additional nutrients in oligotrophic lakes produces in the initial stages the increase in the number of phytoplankton species.

- Bringing the seeds of ruderal and invasive plants, through human activities,  in natural plant communities.

etc.

Iuliana

Hello to all

Thank you for your guidance.

whithbest wishes

Reza

According to some authors, in some bitopes and plant communities, the disturbance can rise the biodiveristy. Disturbance increases the chance for colonising the habitat by new species. However, disturbance also  increases the invasibility  of communities by alien plants and invasive aliens can reduce native diversity at the community scale and the final reslut is the decrease of the diversity.

Here are some helpful articles to this topic:

Hobbs, R. J., & Huenneke, L. F. (1992). Disturbance, diversity, and invasion: implications for conservation. Conservation Biology, 6(3), 324–337 https://doi.org/10.1046/j.1523-1739.1992.06030324.x

Catford et al. (2011). The intermediate disturbance hypothesis and plant invasions: implications for species richness and management. Perspectives in Plant Ecology, Evolution and Systematics, 14(3), 231–241 http://www.sciencedirect.com/science/article/pii/S1433831911000758?via%3Dihub