Andy Holdsworth, conservation biologist
Wednesday, 3 Sep 2003
I woke up half-paralyzed by all of the things I could do with my day. This is all too common. It may become more common because last week I successfully passed my oral preliminary exams — two hours of interrogation by four professors. Fun! With that exam and my coursework behind me, I am free to focus on research. This is a great change, but it comes with a lot of time to structure. Even with today’s scheduled plant census at a suburban forest site, I am always scheming for ways to fit more in the day.
And there is good reason to fit more in my day. I recently estimated that I have five more weeks of intensive fieldwork this fall and more than 850 hours of lab work to do before next spring. I have been incredibly lucky to have a lab assistant help me identify and measure thousands and thousands of earthworms, sort and weigh leaf litter samples, conduct soil analyses, and enter reams and reams of data into the computer. However, as our research funding from the National Science Foundation and private contributions to my advisor’s Center for Hardwood Ecology run low, I will be doing much of this winter’s lab work myself. And then there is all of the data analysis and outreach to organizations and agencies interested in my results. After three intense years of fieldwork and increasing interest in the work, I am especially excited about starting this phase. Meanwhile, the summer field season is coming to a close as the Minnesota temperatures finally drop into the 50s at night and the leaves start falling.
Time to focus on today’s fieldwork in a suburban old-growth forest remnant, the Wood-Rill Scientific and Natural Area. How much biodiversity can urban and suburban nature reserves really preserve? As we struggle to find successful ways to coexist with a diversity of native species in an increasingly urbanized and suburbanized world, this question continues to gain relevance. Wood-Rill is a beautiful forest of stately trees, some of which are about 400 years old. However, it has virtually no plants growing on its forest floor. As it used to have them, what happened? The three major actors we suspect are deer, nonnative earthworms, and other effects of fragmentation. Urban and suburban reserves such as Wood-Rill are typically small fragments that are affected by what happens around them as much as what happens in them.
In the last several decades, deer populations have skyrocketed in the region (and the eastern United States in general). There are many reasons for this including the lack of natural predators and limited hunting of deer by humans and the residential “habitats” that suit deer so well. In these settings, hungry deer can significantly reduce the populations of herbs growing in forest fragments. Urban and suburban reserves are also susceptible to nonnative invasive species escaping from people’s yards. Finally, because these areas are fragments, it can be very difficult for some native plant species to recolonize an area that has suffered from such “disturbances” as high levels of deer browsing or an invasion of nonnative earthworms.
All summer I’ve been driving to various forest reserves in the Twin Cities area trying to sort out how deer, earthworms, and other actors could be affecting these forests’ present and future. How do I do this? One way is to exclude deer and see how the forest plant community responds. Seven years ago a generous neighboring landowner at Wood-Rill contributed funds to install two one-acre fences to keep the deer out. We installed plots inside and outside these exclosures to measure plant abundance and diversity with and without deer. Today I am heading out to conduct the late summer survey. As we had an incredible profusion of sugar maple seedlings in the spring survey and now an intense late summer drought, it will be very interesting to see what has happened.
Always attempting to pack more in the day, after my fieldwork I will be entering data and preparing for another plant census at Wood-Rill. This is part of a new field experiment that I informally call “electro-shock therapy for forests.” Join me tomorrow as I wrangle with the challenges of removing tens of thousands of nonnative earthworms from a forest.