The Broadleaf Papers
Trees have stories to tell, their annual growth rings cataloging changes in the environment, including climate. Many tree-ring scientists focus on conifers, but Neil Pederson, a scientist at Lamont-Doherty Earth Observatory, believes that the less-studied broadleaf trees in temperate forests, such as magnolia, tulip-poplar, maple and birch, have much to teach us.
I walked out of the house Thursday morning when my nose detected it – a forest fire! Having worked for two years in the piney woods of southwest Georgia, I had become accustomed to and, actually, come to love forest fires. That classic line kept coming into my mind, “the scent of fire in the morning reminds me of healthy forests.” The scent can be better than a campfire. It can be a little sweeter. That morning, it filled the entire town. Firefighters were just beginning to quench the fire. As of Saturday night, it had burned about 40 ha (ca 100 acres), but was still uncontained on its northern end. I might have been one of the few people to be thrilled to be in a smoke-filled town. It reminded me that we lived in a heavily forested area, and an active ecological event was playing out just up the hill.
It was fascinating to see the coverage of this fire. There were many resources thrown at it. It is understandable. Clausland Mountain is beautiful, beautiful enough that it is ringed by expensive houses. Twenty-six fire units, composed of about 150 firefighters, were actively fighting the fire (about one fire unit for every 1.5 hectares (3.8 acres)). Two helicopters were brought in to douse the flames. The breathless words of the reporter are fascinating as well, “remote areas” and “extremely dangerous.”
The large response is what happens in the wildland-urban interface, especially outside of one of the largest cities in the world. The conflict between humans and ecological processes has been on the rise as we move out into natural areas and as we become more aware of important ecological processes that maintain ecosystems and the services they provide for humanity. Fire is one of these processes.
So, Sunday we went on a hike to see the impact of the fire. Bushwhacking, we went into the northern end where the fire was still smoldering (though the fire took care of many bushes). It is steep and the ash makes the slope a bit slippery. Much of the leaf litter was consumed, though not completely. In some places, logs were consumed down to the mineral soil. Death shadows are evident. The potentially severe rainstorms approaching from the west should put out the fire. (Update: they did.)
It will be interesting to see how the forest responds. Fire is an important ecological process. It reduces the disease and pest load in an ecosystem; it is an antiseptic in a way. It favors some plants more than others. Like me, fire favors blueberries! Oak trees in the eastern United States do not seem to be regenerating very well over the last 40-50 years. The re-introduction of fire is today’s response to a lack of oak regeneration. Much money is being spent on prescribed fires and education about fire. The lack of oak regeneration seems complex. It is said that the rise of mesophytic species, the species “taking the place” of oak, is changing the forest in such a way that it ecologically dampens the forest, making it hard for fire to take hold. However, the re-introduction of fire doesn’t seem to be having its hypothesized impact – oaks still do not seem to be regenerating in experiments employing fire, while mesophytic species seem to be handling the fire pretty well. Important for the context of this ecological scenario, many changes have occurred in the forest over the last 50-100 years, all of which could be a factor of a reduction in oak regeneration – increased deer populations, loss of important megafauna, and changing land-use and cultural patterns (Hello Smoky Bear!). And, climate change might be playing a direct role in the “mesophication” of the East.
One physical mechanism has been detected – flammability of and differential drying of forest fuels (leaves). Fire is a very physical process. The variation in forest fuels, especially the finer fuels that carry fire in wetter regions, plays an important role in flammability. Thinner leaves absorb moisture more easily. Large, curling leaves, especially lobed leaves, dry faster. Curling leaves make the duff (or “litter”*), the fuel layer, fluffier, allowing better oxygenation of fire, to literally fuel the fire even more. One hypothesis for why eastern forests burn less is the loss of the great American icon, the American chestnut tree. Research by Morgan Varner supports this hypothesis.
It will be especially interesting to see how the Clausland forest responds to this fire. It is getting much wetter in this part of the world. Deer populations are high because of the high human density and the amount of forest preserve in the county (there is no hunting in the area, and deer have learned home gardens are a smörgåsbord). And, the diversity in this little patch of woods is pretty amazing. On our 0.5-mile hike, if that (our 2-year-old doesn’t hike great yet), I spotted 13 major broadleaf tree species, one conifer, the fading eastern hemlock, and two small tree species (I wasn’t even trying to seek out species; there must be more). Amazingly, yellow birch, a boreal species more common to the Adirondacks, New England and southeastern Canada, is mixed in with pignut hickory and sweet birch, species more common to Virginia.
The understory might respond a little differently, though in the little patch we hiked, the wineberry looked just fine. Guess we’ll have to go back out and hike a little more next spring. Shucks.
A pictorial of the aftermath of the November 2013 Clausland Mountain fire.
We met a colleague and his wife on the trail. They were out to check out the fire. They live near the burn and watched the fire grow and the efforts to stop the fire. She noted that it was like a ring of fire. Absolutely!
* = really? Can we get rid of the term “litter”? Fallen leaves, twigs, branches, bud scales, etc., enrich the soil by returning nutrients back to the Earth and increasing the soil’s ability to retain moisture. If that is “litter,” call me trash.
It was midday. It was dark. It was June! It was pouring. We were sitting in my folk’s cabin in the Adirondacks when my dad groaned, “This is depressing”. Later on that same day, a hometown friend made a similar exclamation. Elizabeth’s update triggered a deluge of similar sentiments. During that discussion, she made reference to The Long Rain. It was the perfect comparison. Judging from the sentiment in our cabin, in the newspapers, and on Facebook, Central New York was on the edge of insanity because of the unrelenting rain.
It was too early in the season to write this post. Predicting future rainfall is like trying to predict Dennis Rodman’s next career move: It will move in a new direction, but no one can pinpoint the trajectory. But now, as Cortland and Macoun apples grace us with their presence, we can now safely say that summer is over (I do not care what the tilt of the Earth says. It is apple season!). In fact, the Northeast Regional Climate Center and NOAA have completed an early overview of this past summer’s climate. Their conclusion regarding precipitation in the Northeastern US? The Pluvial continues.
Actually, these overviews typically discuss climate of just the most recent month or season year or versus the “climate normal.” While useful, these summaries do not paint the full picture. Consider this: A climate normal is often based on a recent 30-year period, like 1970-2000. Now consider this: Instrumental records for the Northeastern U.S. (below) and analyses for the Catskills region and southern New York State, here and here, indicate that since the 1960s drought, the region has seen a substantial increase in precipitation; in fact, hydroclimate seems quite unusual since 2000. Now really consider this: A tree-ring reconstruction of moisture availability indicates that the recent wetting comes at the end of a 120-180 year trend (and maybe longer). So, the daily comparisons on TV or other media sources are typically based upon recent climate and ignore the past. Thus, based upon paleo records, the full picture indicates that we are sitting in one of the more unusually wet periods of the last 500 years.
I return to this topic because of: 1) the many implications of this climatic shift and, most importantly, 2) what seems to be a limited amount of public awareness of how wet it has become in recent decades (though this awareness is growing). The substantial change in moisture across the Northeastern U.S. (the draft of the 2013 3rd assessment is here) is more commonly known in the scientific literature, but it seems to be less well-known outside of that community. For example, under the tab “Climate Change” on the Northeast Regional Climate Center’s excellent web resource, one can only find minimum and maximum temperatures when seeking to understand how much the climate has changed. An increasing trend in precipitation just doesn’t seem to grip the attention of most people like an intense heat wave or drought. In fact, an editor remarked to a freelance writer that they’d only do a story on the change in precipitation in the NYC region if “they were painting the lawns green on Staten Island.”
For the people in Vermont, the Catskills, Mohawk Valley, and those wishing to use beaches in the summer along the coast, this seems a bit short-sighted. Excess rain is costly. It costs the people still trying to rebuild in the Catskills from the flooding of 2011 (and it isn’t just the two tropical storms that triggered the flooding – new research indicates that because the soils were saturated, the impact of Irene and Lee were worse than they might have been in other times). It costs people in Vermont wanting to rebuild their cultural heritage. It will cost all of us in NY State if tax breaks are given to expand flood relief measures in five counties and restoration and reconstruction of managed water systems; climatic change disregards political boundaries. It might cost us if we are managing forests for a long-gone climatic era. It further erodes trust between country and city folk as well as citizens and their government. Tragically, it costs lives.
So, as we become aware of the impacts of additional rainfall (and certainly there are additional costly impacts than what is listed above), we need to know that precipitation is likely to increase over the coming century. Model projections indicate it is likely that the Northeast will get wetter and have more extreme rain events. This doesn’t mean we will not experience droughts in the future, nor does it mean each summer will be like 2011 or 2013. And, these model projections could be wrong. But, our state of knowledge indicates that these Long Rain conditions could become more common.
This shouldn’t be viewed as more environmental doom and gloom. Humans have enormous brains and know how to use them! See: Klaus Jacob. We have the ability to prepare for potential adversity. And, if it isn’t clear by now, humans are one of the more adaptable and flexible animals on the planet. Heck, we might even celebrate wetter conditions with some enormous fun. And, from my Broadleaf perspective, the Northeast could become a temperate rainforest with bigger trees and a denser forest.* Folks spend enormous money to experience such things.
* unless future warming overwhelms our rain wealth and stunts the future forest…. apologies. It is hard to avoid all of the potential doom and gloom…