Secondary ecological succession in Palikir

With all due thanks to the maintenance crew up front, the area across the road from the campus is, at present, providing an excellent laboratory for secondary succession. Work done last term on leveling the terrain there provided bare soil of poor quality.


One of the early arrivals was Nostoc, a surface dwelling cyanobacteria.


Other small grasses and herbs also moved in quickly to the open terrain.


The textbook mentioned lycophytes as being early colonizers of infertile open ground, and indeed Lycopodiella cernua is a first arrival in this area, a pioneer plant.


Another early arrival is the sun loving fern Dicranopteris linearis


Along with the lycophytes, ferns, and grasses, trees are also quick to exploit this open terrain, especially the nitrogen fixing tree Falcataria moluccana. Morinda citrifolia is also quick to move into open spaces.


Falcataria moluccana quickly forms a lightweight canopy which has the effect of reducing the growth of Ischaemum polystachion (paddle grass) under the trees.


The area to the west is transitioning towards Falcataria dominated forest, but this is not a final stage. 



Trees which provide more shade such as Campnosperma brevipetiolatum establish themselves. Under their dark shade the grasses cannot thrive.




In the distance Campnosperma brevipetiolatum rises up above the Falcataria trees and has taken over dominance in this older growth area. 


Close up of Campnosperma brevipetiolatum.

Comments

  1. That is so interesting! Which photo shows what it is today? And how many years did it take? I am commenting her from far a way a different climate. The area I was posting Nostoc from was also from a destroyed area. It burned totally (soil incl) 70 years ago, now there are small trees, but as you saw still some areas with Nostoc.

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    1. The photos were all taken on the same day. The area with the Nostoc was leveled with a bulldozer last year. An area to the west was leveled with a front loader about a decade ago. And further west, where the trees are, is an area that was leveled back circa 1995. Many of the trees are fast growing Falcataria moluccana. The area is an accidental succession laboratory with some areas undisturbed for almost a quarter century, others more recently disturbed. That I have taught here since 1992 helps me know the history of the landscape!

      The Campnosperma brevipetiolatum in the distant background of the one shot are the oldest of the trees and predate the 1995 land clearing. Most of the Falcataria moluccana is very young, a decade old or so. By 20 years F. moluccana is a towering tree with a height over 30 meters. The tree is a very soft wooded member of Fabaceae and grows exceptionally quickly. Technically an invasive plant, the tree is burns green. As a result local residents use F. moluccana as a source of firewood, which keeps pressure off of the slower growing, less competitive endemics.

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