It is also possible that the germination process for the pines is very slow and the first year or two takes place out of site. It might be that once there was adequate light and moisture, it still took a long time for the seedlings to become visible. Trillium plants, for example, take 7 years to go from seed to flowering plant.

Martha

Oaks are somewhat allelopathic, though less so than, say, black walnut. Perhaps it's some mixture of that plus what gardengal48 says -- competition for sunlight/water. It would make sense that some time might be required for allelopathic compounds in dead leaves/roots to break down. It could also be weather: a warmer/colder or wetter/drier season that favors pine germination.

You're wanting something more open/diverse? If so I would think continual disturbance would be necessary in your neck of the woods.

I have english oak in my woodland (Quercus robur) and, while it does offer a canopy of dense shade, there are numerous early spring carpeters growing under the canopy. Allelopathy is an interesting phenomenon - I am beginning to suspect that nearly all plants have a degree of allelopathy once I started thinking of plants as communities rather than isolated specimens. A sort of throwback to my old veggie growing days where we talked ofcompanion pairings, both favourable and not (alliums always featured prominently) I imagine that the obvious contenders such as black walnut are allelopathic to a wider range of plants but would be unsurprised to learn that allelopathy occurs on a wider spectrum and, along with the microbial life of the soil, interacts on a contingent basis as the environment changes. In other words, not a fixed syndrome but one which can be triggered into play much like enforced dormancy or even gender changes.

A boring dreary english afternoon - do feel free to pass by these ramblings.

Campanula, I think you're likely onto something. Just as with mycorrhizae, a group of organisms once relegated to the sideline of what's going on in numerous plant communities, but now understood to be everywhere and of immense significance to forest health. I suspect that acid precipitation across parts of Europe, leading to declines in the suitability of the site for the microorganisms, is behind recent and widespread tree health declines there.

And the almost unbelievable findings in terms of an almost "neural network" linking the trees within a stand to one another via these same hyphal strands is beyond cool. no reason why we wouldn't be equally ignorant about the allelopathic thing.

+oM

I am beginning to suspect that some trees are allopathic to their own kind or maybe a mature tree has eaten up a certain nutrient in the soil that is needed by the young seedlings to thrive. I am trying to encourage red Spanish Oaks ( Quercus buckleyi) and they Never ever come up close to the parent. I now make my brush piles down hill from the parent to create deer protection, soil, water and compost capturing structure to encourage sproutage. I used to think under the canopy was a good place but it did not bear fruit.. Juniperus ashei have no problem spouting under the oaks. Can you tell, I have never studied plants except in my own school of The Outback Academy. Someone please give me a scientific explanation so I can sound smart in the future. LOL.

A glorious sunny make believe spring day, 76F

A common, easily seen factor is competition through shading.

Oddly enough...or not odd at all as it's turning out... individual trees in the forest can actively shunt nutrients, not only to others of their kind, but across species and genera. This via the hyphal network of those fungal species involved in mycorrhizal relationships with the trees. I already knew momma tree could send photosynthate and other materials to little baby tree of same species, but now it's turning out these fungi are far more likely to cross-connect with a range of species. Trees, in this sense, really and truly could be said to communicate with one another. Very likely, many of the same processes are underway in grasslands too. So long as the substrate has not had one or more nutrient levels unnaturally hyped up via overuse of fertilizers, these organisms will be present, quietly doing their work.

+oM

Here the baby will not sprout unless it is a distance from the oak canopy. But it is not a shade issue because under the oak canopy gets more light than under a cedar canopy where they do sprout. the winter time has the oak loosing its leaves. Cedar come up like a vengeance under the oaks and end up out competing the oak.

You might find the introduction of this paper interesting:

Effects of germination inhibition on the dynamics of Quercus ilex stands

It's not about your specific Q. species, but they find some evidence of auto-allelopathy. They don't really get into the why of it. I can imagine that it might be advantageous for new seedlings to be some distance away so that they are not competing with the parent for resources.

Very interesting. My woods are in transition but it is a non burnt fire dependent ecosystem that has been historically over grazed and now "managed" by a dilettante.. God knows what stage of disturbance it is in.