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Another possibility is that the soil was so degraded that only crummy grass could grow there. Perhaps the larger native plants, which are more complex organisms

by kevmo 9y ago

Another possibility is that the soil was so degraded that only crummy grass could grow there. Perhaps the larger native plants, which are more complex organisms, need nutrients in greater quantities than the grass. So it's less about beating back the invasive grass and more about establishing necessary conditions for native growth. These more complex organisms then create shade canopy that other native species can thrive in (and which is bad for grass). This is an extrapolation of my my experiences with composting. A greater number of plants can grow in rich soil, period.

jonchang 9y ago
Yes, this is what I was referring to when I mentioned "massive additional organic nutrient input". Unfortunately the authors experiment design isn't sufficient to show that this is the case since again there are other factors at play. But it's certainly a possibility.
- kevmo 9y ago
  Indeed. The soil pH, while important in and of itself, seems like a bit of a red herring (or maybe a secondary story) when evaluating the macro-changes.
TheSpiceIsLife 9y ago
Pioneer species are hardy species which are the first to colonize previously disrupted or damaged ecosystems, beginning a chain of ecological succession that ultimately leads to a more biodiverse steady-state ecosystem.[1] Some lichens grow on rocks without soil, so may be among the first of life forms, and break down the rock into soil for other plants.[2] Since some uncolonized land may have thin, poor quality soils with few nutrients, pioneer species are often hardy plants with adaptations such as long roots, root nodes containing nitrogen-fixing bacteria, and leaves that employ transpiration.[1] Adding compost speeds the process along by adding nutrients and inoculating the soil with insects, bacteria, and fungi. 1. https://en.wikipedia.org/wiki/Pioneer_species https://en.wikipedia.org/wiki/Pioneer_species

by kevmo 9y ago

jonchang 9y ago

Yes, this is what I was referring to when I mentioned "massive additional organic nutrient input". Unfortunately the authors experiment design isn't sufficient to show that this is the case since again there are other factors at play. But it's certainly a possibility.

kevmo 9y ago
Indeed. The soil pH, while important in and of itself, seems like a bit of a red herring (or maybe a secondary story) when evaluating the macro-changes.

TheSpiceIsLife 9y ago

Pioneer species are hardy species which are the first to colonize previously disrupted or damaged ecosystems, beginning a chain of ecological succession that ultimately leads to a more biodiverse steady-state ecosystem.[1] Some lichens grow on rocks without soil, so may be among the first of life forms, and break down the rock into soil for other plants.[2] Since some uncolonized land may have thin, poor quality soils with few nutrients, pioneer species are often hardy plants with adaptations such as long roots, root nodes containing nitrogen-fixing bacteria, and leaves that employ transpiration.[1] Adding compost speeds the process along by adding nutrients and inoculating the soil with insects, bacteria, and fungi. 1. https://en.wikipedia.org/wiki/Pioneer_species https://en.wikipedia.org/wiki/Pioneer_species