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9. Model ing Eelgrass (Zostera marina L.) Distributi ons in Great Bay
New leaves are generated based on the plastochrone interval of leaf generation (PI Model) and the number of shoots in the eelgrass bed:
Where:
Per_oLmax_light =percent of maximum light that reaches eelgrass (unitless)
ratio =average amount of new leaves created per new shoot
(leaves/ shoot)
Nrcf sboots =number of shoots (#)
PI_Model =plastochrone interval model (day)
Leaves are lost based on the plastochrone interval of leaf loss (PI Discard)
and the loss of shoots. Conceptually, when shoots are lost, leaves will be
lost as we ll:
loss ofleaues =IF Disca rded_shoot >0 THEN (Nr_oLleaves/(PI_discard))
+Loss_oL shoots*lvs-per_shoot ELSELossofsboots'luspersboot. (12)
Where :
Nrofleaoes = number of leaves in the bed (#)
PI_Discard =plastochrone interval of leaf loss (day)
Loss ofsboots =loss of shoots (#/ day)
Lvs_per_shoot =average number of leaves per shoot in the bed (#)
The number of nodes forms the basis for which new shoots form in an
eelgrass bed. The total number of nodes is calculated as the difference between the generation of new nodes and the loss of nodes when rhizomes
are lost:
Nr_oLNodes(tJ =NrcfNodestt-dt) + (Neui Nodes-Lost Nodes) *dt.
Where:
(13)
Nr_oLNodes =number of nodes (#)
New_Nodes =generation of new nodes (#/day)
LostNodes = loss of old nodes (#/day)
New nodes are formed when new leaves form (New_Nodes =New_leaves).
Nodes are lost when rhizome s are lost (as calculated in the roots and rhizomes subrnodel):
LostNodes =3 .0*(discarded_R&R'/Length _between_Nodes). (14)
Where :
Length_between_Nodes = average length between nodes (centimeters)
Discarded_R&R = discarded rhizomes (centimeters)