A Neotropical Savanna

In June we experienced a record rainfall of 43 inches. The previous record was 41 inches and the average for this area is 22 inches in June. Here’s a graph of the erratic 2010 rainfall (red line) compared to a 16-year average (blue line).

Back in May, I noted the early blooming of Miconia rubiginosa after the heavy rains in April.

Now, in July, I’ve seen two plants in bloom that I normally see bloom in August: a tree with large bunches of yellow flowers, Senna hayesiana, and a miniature relative of the Elephant Ear herb, Xanthosoma mexicanum. I’m also seeing flower buds on an unidentified Miconia that usually blooms in September. I’m sure more’s going on along this line than I’m seeing.

Maybe these large swings in time of blooming are relatively normal for the tropics. But I’m starting to think that it’s more than coincidence that different plants from three unrelated families (Senna = Fabaceae or bean family, Xanthosoma = Araceae or arum family, Miconia = Melastomataceae or “black mouth” family)  are blooming immediately after uncommonly large monthly rainfalls.

One of the events I look forward to in June is the blooming of the iconic tree of our area – a canillo. It is Miconia rubiginosa. It has a distinctive look – trunk a little gnarled, bark rough and reddish, leaves in clumps at the ends of the branches.

When it blooms, in June as I said, the whole grove lights up.

But this year it bloomed in early May, nearly six weeks earlier than usual. (Sorry, but my pictures from that day are horrible. The blooms, though, looked like these, above and below, taken in June last year.)

Why such an early bloom?
Plants may not bloom at exactly the same time every year, but it struck me that this year’s early blooms might possibly have something to do with the heavy rains in April.

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One of the more common trees in our area is this one, often called sangrillo in Panama. Sangrillo means “a little red” from sangre, for blood, and -illo giving it the diminutive form. But when you first see the tree you don’t see its little red blood. What you notice are the brown or light green undersides of the leaves and, most of the year, the globular buds at the ends of the branches.

When I first thought about identifying this tree, I zoomed in on those leaves. The color of their undersides reminded me of many of the Miconia leaves around here. At least one species in Panama is called dos caras – named for the “two faces” of the leaves.

But a quick look shows that the sangrillo (left image below) lacks the longitudinal veins of the Miconia (right image below).

      

Since those longitudinal veins are characteristic of the entire family to which Miconia belongs – the Melastomataceae – and the sangrillo doesn’t have them, then I thought I’d better start the identification from scratch.

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The winds earlier this month caused more damage than a downed Miconia tree, and the damage was more extensive than I realized until I compared the most severely injured area with an earlier photograph. Here are the before (November 2008) and after (February 2009) shots. (Click on image to enlarge.)

The wind damage is compounded by the contrast between the conditions at the end of the rainy season and conditions two months into the dry season. Before I go into that, I should explain the sticks leaning against the banana plants. These are crutches put there to support the plant once a bunch of bananas develops. If the plant is not supported, the bananas will pull the plant down. The bag is placed over the ripening bananas in an attempt to keep the birds away (Black-chested Jays are especially noisy and destructive).

Okay, here’s the damage report. (Click on image to enlarge.)

In the upper left corner is a leaf-less tree (deciduous in the dry season) that I have not yet identified. A large limb split off it and fell onto an already fallen Miconia and onto one of the banana plants. The Miconia has been mostly cleared away, but it also damaged banana plants and for awhile provided a highway for squirrels to get to the ripening bananas under the bag. The Miconia also pretty much demolished the fern stand. As noted, banana leaves normally take on a shredded appearance in the dry (and normally windy) season. They are designed to do that without causing damage to their vascular systems.

And here’s the comparison between the seasons.

At the end of the rainy season the grass is green; in February it is brown. The banana leaves are fairly intact in the rainy season and are shredded in the dry season.

The bijao (the large-leafed plant at the extreme right of both images, Calathea lutea) is bright green in the rainy season, and not all of the leaves are erect. In the dry season, the leaves are grayish, shredded like the bananas, and nearly all are completely erect to expose themselves to less sun than if they were more parallel to the ground (this movement of the leaves is a characteristic of this groups of plants and for this reason they are known as “prayer” plants).

Between the bijao and the bananas is an Eugenia biflora, which has just finished blooming and so looks a little paler than it normally would because it is studded with pale green developing berries.

All in all, with the wind damage and the normal drying impact, the pleasant little area looks pretty devastated. However, it’s a miniature ecological event as well. At the edge of our tiny forest, a new “gap” has been created. It will be interesting to watch as it responds to this new situation.