At the suggestion of Virginia nature friend Pat Bowman, how about wild plants and hurricanes. Do the wild plants care?
Some relocate. It seems that during Hurricane Wilma in 2005, a tropical weedy grass. Steinchisma laxum, previously unknown in North America invaded South Florida Florida arrival was overdue, an easy breezy hurricane hop from the Caribbean, assuming the hurricane did it. Blog co-conspirator John Bradford standing in Halpatioke Park was the first soul in North America to say, “hey this does not fit the measurements of any grasses expected around here.” Now you can hardly escape it.
My lawn today still has on it millions of small leafy twigs shed from Live Oaks. It is obvious to reckon, “well the gusts blew those free.” True, and branches whipping wildly knocked them off too. But there’s more to it than immediate physical damage. That something more is cladoptosis, defined as “planned” twigdrop. It happens in certain trees, notably in Oaks.
Earlier research indicates the tree somehow “decides” which twigs shall live and which shall shed. Determination occurs early in the life of the twig. Those fated to shed follow an odd development: the “veins” connecting them to their parent branch narrow and choke off supply. It looks like a ring of decay girdles the twig at the snap-off point, and the bark appears to pinch in. When the twig separates, the severed base is not fractured and splintered, but rather more of a rounded knob, like your femur joining your pelvis, essentially “designed” to drop free smoothly.
Why? The limited literature indicates a hormonal seasonal reaction abetted by stress. In short, those scattered twiglets were poised to come loose before Irma roared in. The storm merely shortened the timeframe to hours instead of weeks or months. The tree conceivably needs all its leaves during the moist growing season, but can’t support the full canopy as the warm wet season winds down and dry times approach. The hormone ethylene is implicated. The same hormone serves commercially to defoliate crops for easy harvest. The twigdrop helps storm-proof the tree by reducing wind drag. How many wind storms does a 500-year-old Live Oak experience?
Although Slash Pines may fracture or topple, another common probability is shedding, not little twigs, but rather large dead branches low on the trunk. Ever notice how those trees have nice green canopies up high but not many dead branches down low? There’s a perception that the branch-shedding is protection from ground fires, and that maybe those old branches even have some basal weakness to set them free. “Cladoptosis” of large branches? Maybe…more research needed. The break-off is not clean, uniform, and mechanical as the Oak twigs. Walking in The Haney Creek Natural Area today John and I saw the broken pine branches to be all sizes, alive, and dead, and torn and splintered. Less convincingly “preplanned” than Oak twiggies.
Many woodland trees lie prostrate from past thunderstorms and hurricanes. My favorites are in swamps: Red Maples and Sweetbay Magnolias where the fallen tree resurrects multiplied as branches rise vertically to become new trunks. Ex uno plures! From one comes many, a whole new mini-population.
Busted-off branch bases and torn bark on standing tree trunks invite trouble and may or may not heal. Healing comes mostly from above, which is why branch-stumps tend to fare poorly…”above” is gone. Sugars, hormones, and growth processes cover a wound mostly downward, like pulling down a window shade.
After pruning, grazing, or hurricanes new stems grow from the lateral buds situated where the leaf joins a skinny young twig. Repeat, skinny young twig. But on any tree damaged in a storm a few years ago new branches sprout from the thick old trunk. How can that be, that gnarly old trunk lost its lateral buds decades ago. Well, not entirely, that old bark has an amazing emergency repair mechanism known as latent buds. Latent buds creep outward hidden within the bark as the tree expands, waiting for hurricane day. The equivalent of me sprouting a new leg should one be yanked off.
The magical regenerative powers of plants go doubly in an environment where storms and fires are endemic, such as here. Check a wild area after a major storm, and there is likely less damage than expected, in some places no damage is even detectable. That was almost true in Haney Creek today, Liatris all abloom, Hog Plums with plums still attached, and most foliage intact and green. The native flora evolved to stand up to trouble. And where destruction does occur, the ability of life to rise from subterranean structures or from broken plants is quick. Moreover, the soil seed bank is ready to rise. Disturbed dirt never stays bare for long.
If you want to find damage, seek it near the sea. The salty winds “burn” foliage, and sow salt into the soggy earth. The plants mostly recover ok from the saline attack. Guess what species is especially resistant. Live Oak.
Does a big hurricane change the composition of the flora? Sure, within the constant ebb and flow of species in our dynamic world, but, given the fact that our flora has evolved through thousands of hurricanes, one event won’t cause radical mischief, except maybe where human activity has created an unnatural imbalance.
Upon emerging from our bunkers the morning the tempest subsided, one of the most positive sights after, “hey, we still have a fence,” were blue jays and butterflies. Where did those jays ride out the fury, and a butterfly in a hurricane, well, that’s just poetic.