The Influence of Drought on Maritime Tree Health

The end of a lazy summer filled heat, drought and smoke events has brought more attention to regional declines in certain tree species, especially when in more exposed conditions such as greenspace and bluff edges. Signs such as brown edged maple leaves, browning needles in conifers, and premature leaf loss and decrease in leaf density in multiple species (both deciduous and coniferous) have been personally observed.

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Trees showing natural resiliency (such as Shore Pine, Maritime Juniper, and Garry Oak) to climatic extremes are doing better than others. Mature Douglas Firs can go into a process of retrenchment to minimize use of available tree structure in response to climatic stresses. 

The current tree owner can promote longer-term tree health in a variety of ways. Some maintenance items that will help improve prospects of a couple of specific species:

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• Clean up dead needles off plant and on ground around Weeping Atlas Cedars and alpine conifers to ward off fungal infection.
• Leave yearly needle mulch around native coniferous species and increase mulched area (not to exceed 3-4” depth) to just beyond dripline if possible.
• Check valued tree stems for little sawdust piles (frass) left by leaving opportunistic beetles.
• Check for fruiting bodies of fungi near your valued trees and try to learn if they are companions, distant friends, or enemies. Supplement friendly relationships while being forewarned about increasing risk from negative relationships.
• Think about adding root shading and a drip watering system around valued trees that are not resilient to heat and drought stresses. It may also be useful to do soil nutrient and pH test to see if the current growth area can be further supported.

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As a winter task, try to inform yourself a little about creation of dead wood habitats for animals and how changes in tree species diversity in this region will affect you as the educated will have yards that outperform others in terms of sustainable tree health and richness of associated living creatures (native habitat).

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Your in trees,

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Sal

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