The Arbornaut, page 16
In my obsession with how insects impacted the aerial salad bar, I almost overlooked what they might be doing to the rest of the tree, especially the root systems, until I noticed Christmas beetles living in the soil during their grub phase. It seemed important to document their underground activity, to essentially return to that big toe of the trees and determine what was happening below. But how does a field biologist measure root damage? As it turned out, there was only method: demolish the tree and examine its roots. For this activity, as with earlier canopy research, I recruited Earthwatch volunteers, whose eyes and ears made the work more comprehensive. They stayed in our rustic shearers’ huts and helped map both above- and belowground insect damage to gums. Our farm equipment was a boon for root research because a tractor could effortlessly excavate soil to expose roots and beetle grubs. First, using a cherry picker, the team carefully harvested the aboveground parts of one healthy New England peppermint and one identical-sized dying individual approximately one hundred feet away. Every cubic yard of foliage, branches, and trunks was mapped, cut, and bagged or labeled for analysis in our woolshed laboratory. Then we used the farm tractor to extract the roots. My farmer husband carefully dug trenches in and around the two trees so that the citizen scientists could use careful hand-sieving to extract all the roots. We all literally played in the dirt for several days. The results were astounding! Thanks to John Deere plus a team of citizen scientists, we calculated the magnitude of both canopy herbivory plus root damage by Christmas beetles. We weighed cookies (cut sections of trunk), counted every single leaf, and measured the defoliation of each tree. A healthy peppermint had a total canopy area of 161 cubic yards, representing just over 150,000 leaves. In contrast, the dieback tree had one-third of the leaf material, distributed across 90 cubic yards and totaling only 60,000 leaves. Borers had also attacked branches, eating away 19 percent as compared to a more moderate 5 percent loss in the healthy tree. Root damage from beetle larvae was even more vivid: the dying tree had only 20 percent remaining root matter as compared to its healthy counterpart. In short, Christmas beetles and their grubs were consuming peppermints at both ends. It was a double whammy—grubs fed underground and then emerged as adults to eat the leaves.
This research measuring insect damage to both roots and canopies was completed only because of my mom’s heroic assistance. Midway through pregnancy, I developed dreadful vertigo and had to forgo all physical work, including cherry-picker activities. My intrepid mom came all the way over from upstate New York specifically to cook for the Earthwatch teams. In those days, it was at least five flights from Elmira to Walcha, with stopovers in Pittsburgh, Los Angeles, Hawaii, and Sydney to refuel and change planes. We laughed, because she outright refused to replace me in the cherry picker, and she certainly did not appreciate the swarms of blowflies in the kitchen, nor the venomous snakes in the grass. But thanks to her efforts, volunteers were well fed as they measured every inch of those eucalypts.
During pregnancy, I gained fifty pounds. It was considered a sign of good health in the outback for pregnant cows and ewes to gain lots of weight, so I guess the same rules applied to humans. Ten days past the due date, I was not only enormous but also anxious. For three afternoons in a row, I stumbled along the ruts and furrows of our back paddock behind the farm cottage. My mother-in-law insisted that this type of rough walking would incite labor. It was 1985 and farmers were all lamenting about climate extremes wreaking havoc on the agricultural and grazing industries. In a desperate effort to stay ahead of El Niño, we had just planted oats. Our sheep could not live through another season with the native grasses so sparse, so we hoped to offset their impending starvation with a higher-nutrition oats crop, but even that was a gamble because it would need to rain at least a few times for the oats to grow. I tripped and flailed through the rock-hard crusts of dry soil flung onto an undulating landscape by the plow, big enough blocks to break a leg if I was not careful. There were no artificial inducements for labor in our twenty-three-bed outback regional hospital, and despite the absence of technology, I had absolute trust in our country doctor. His simple practice offered no ultrasound, no election for an epidural or cesarean delivery—but many years of practical experience. If complications arose, I would be flown to Sydney via the Flying Doctor Service.
Eddie was born after thirty-six hours of labor. No drugs, no scans, no modern equipment. Most of our cattle did not undergo such an inhumane experience, as my girlfriends murmured. After the first twelve hours of labor, when it seemed obvious my progress was not accelerating, our faithful general practitioner wisely went to bed. I was relieved that at least one of us might get some sleep. At 4:00 a.m., the delivery table at the hospital collapsed when the nurse accidentally bumped it, and I tumbled to the floor. My handy husband got his toolkit out of the truck, fixed the broken joints, and lifted me back onto the repaired table. Some twenty hours later, after excruciating contractions and no painkillers, Dr. MacKinnon said I had his permission to swear. I was so exhausted my brain couldn’t process anything, but I needed to muster one final burst of energy to deliver the baby so meekly said, “Jeepers creepers!” For months afterward, the entire community chuckled over that so-called expletive. After an overwhelming amount of breathing, pushing, and tapping an innermost fortitude, Eddie was born from a breech position, weighing almost nine pounds, but happy and healthy. I required a lot of quilting, as the doctor called it, from excessive tearing during childbirth. In the outback, one can only hope for good health and good luck because the technological trappings of modern medicine are many hundreds of miles away. I spent a week in our rural hospital, barely able to walk after all the stitches. But on the plus side, there was no rush to leave and no suspicion of baby substitution as occasionally reported in large urban facilities. In fact, no other babies were born in our rural hospital over the entire month, so Eddie was spoiled by all the nurses. When I first got home, some American childhood friends making a round-the-world trip showed up at the local gas station while driving from Sydney to Brisbane, hoping to visit. The attendant smiled and told them I never answered the phone between 10:00 and 11:00 a.m. because I was nursing the baby. Such was the level of close-knit knowledge shared in rural communities—everyone knew everything, or so it seemed. And I loved that sense of connection.
After the birth of our first son, Eddie’s dad was proud and my in-laws were beaming, as was Eddie’s Australian great-grandfather. He and I were remarkably close, sharing a love for birds, and despite his age of eighty-six, he drove every afternoon from his house a mile up the dirt road to have tea with me and watch birds at the kitchen window. He died several months after Eddie was born, and I secretly believed he was merely waiting for the arrival of a great-grandson before departing this earth. Even in the late twentieth century, male children were the major currency for successful inheritance of a working farm. Edward Arthur was named after both grandfathers, which were big shoes to inherit. Struggling with a newborn, I was hit hard by cultural attitudes confronting me on all sides, especially from the in-laws, who made it clear that a daughter-in-law’s role was at home with the baby. Period. There was no childcare within a hundred square miles, and no immediate family offering to help. So I was pretty much locked in as a full-time “mum.” A few colleagues at the university noticed my absence, essentially those researchers studying bird populations and tree-planting trials and pretty much comprised our entire dieback team. When I asked my advisor if I could ever resume field research after having a baby, he simply suggested returning after one week off. Fat chance! (He also admitted he was part of a generation where his wife did all the child-rearing in their household.) Fortunately, I had a backlog of data that could be analyzed at home.
Housekeeping for a rural farm operation was already pretty much a full-time gig, but it became double duty with a baby. In the absence of a clothes dryer, the terrycloth diapers needed hanging on that backyard Hills Hoist. I cooked lamb a hundred different ways, and we ate our homegrown livestock almost every day. Baby food required cooking, straining, and sieving; it was not available in cute little jars at the grocery store. Men needed morning and afternoon teas when they dashed home from the paddocks, and because I made real coffee (my mother-in-law preferred instant), our kitchen was the favorite stop. Constant household battles were waged with blowflies, water shortages, dust, and venomous snakes. We found a family of red-bellied black snakes living in our outhouse next to the kitchen; I was not amused, but the men all laughed. We once found a dead sheep in our water supply and smaller bits of biodiversity (aka scum) lived in the roof gutters that drained into the belowground water tank. In hindsight, we probably ingested amazing microbes living in the outback, which may now confer immunity to some unknown pandemic. But there were also immediate dangers, such as when Eddie nearly grasped a brown snake around its neck while helping me turn on a hose in the garden. Both faucet and snake were brown and erect, side by side, but a brown-snake bite could kill such a tiny person. I grabbed Eddie in the nick of time, dashed indoors, and returned with the family shotgun. Andrew taught me how to shoot snakes, although I never really intended to do so. But this encounter made my blood boil. A venomous snake threatening a tiny boy in his own garden. The mom instinct is strong! Lucky for that snake it disappeared before I could take aim. At the best of times, I appreciate snakes, and have even dedicated research time to these important creatures. But as a young mom, I could not reconcile poisonous snakes and toddlers slithering in the same space.
When James was born sixteen months later, the nurse apologized with a wink for “accidentally” breaking my water with her fingernail. Remembering the long labor with Eddie, she could not bear to see me repeat such a prolonged episode. This time, after only ten hours of labor, James was born and immediately cried with hunger. He was big and strong and seemed ready to devour a steak. Having a second boy catapulted me to greatness in the eyes of my in-laws. Despite the scarlet S on my chest for SCIENCE, I briefly became a source of pride and joy. Birthing two boys was akin to winning an Oscar, ensuring succession of the ranch. Our sheep property was entering its sixth generation, all through male bloodlines. Andrew was the only male grandchild, so his life had been predetermined in many ways. Those hundred-plus years of family succession had seen their share of droughts, disease, invasive weeds, rabbits, snakebites, deaths, and financial struggles. Life on the land is truly tied to the weather, making it a lottery for survival and success. Whenever Andrew and I went to a pub, the graziers talked about weather, livestock, and little else; women mostly exchanged recipes and child-centric stories. A few pubs in our district excluded women completely, only offering a ladies’ waiting room. When, on rare occasion, I accompanied my husband into the pub, the men looked at him even if they were talking to me. Such behavior reaffirmed an unspoken sense among men that women were inferior. One weekend, we went to a party hosted by one of Andrew’s mates. Standing around a barbecue in the backyard, the host grabbed me in a very personal place. I immediately bolted back indoors. Unfortunately, the sliding door that was open when I came outside had since been closed, so I smashed into the glass, landing on the ground with my face bleeding. I ended up in the hospital getting stitches. When I whispered to Andrew about the incident, he felt it would not do any good to share the truth of the groping incident. Instead, everyone simply chalked it up to a woman’s weakness with liquor. Although I was tempted to be angry, I had to accept this as a liability of my gender and the culture into which my husband was raised.
Not surprisingly, two toddlers turned my life upside down, especially in the absence of disposable diapers, day care, or convenience foods. Like their mom, the boys learned a great deal from trees in their childhood. We had no near neighbors, sidewalks, or playgrounds, so we spent lots of playtime observing nature around the sheep station. I taught them to sniff the scented juvenile leaves of New England peppermint, hide behind stringybark trees with their hanging bark strips when kangaroos approached, spot koalas feeding in eucalypt crowns, and watch a bowerbird collect blue fruits for his lovingly constructed courtship boudoir under one of our garden elms. What solace for me that my husband’s grandfather had planted English elms along the driveway. Now their giant green canopies provided deep shade in an otherwise parched landscape and reminded me of the elm growing through my childhood lake cabin. Both boys learned to count using gum nuts, smell the fragrances of eucalypt oils, and fine-tune their hearing by learning songs of resident currawongs and kookaburras announcing dawn in our black sallee trees.
One parallel between eucalypts and my young-mom status was the “mother tree” phenomenon. In the scientific literature, some temperate species have been given the affectionate term of “mother trees” because they appear to share underground resources between adults and juveniles. A mature individual with extensive mycorrhizae (fungal associations that advantageously take in water and nutrients from the soil) may share resources with nearby juveniles. In the tropics, however, growing up near a parent tree often leads to greater likelihood of attack by predators because juveniles are easier to find, so seedlings usually have greater success germinating far away from conspecifics. Consequently, the juveniles in tropical forests are not likely to grow close to a parent, making the mother tree behavior unlikely. I did some limited work on mycorrhizae in tropical trees after my PhD was completed, and published a paper with my advisor, Joe Connell, theorizing their underground network conferred a competitive benefit for water and nutrients to certain species that had mycorrhizal partnerships. We formulated this idea because some tree species grew in dominant patches in the tropics and we hypothesized that they outcompeted other species via underground resource-sharing. Tropical forests, however, are renowned for the existence of highly diverse stands, meaning mothers and children of the same species don’t usually live nearby nor do they assist their own kind through an underground network. Scientists now recognize that trees “communicate” in at least two ways: via underground connectivity as well as aboveground emission of volatile oils from the leaves, which are airborne to warn neighboring trees when defoliators are attacking.
Another mother tree concept I observed in tropical trees as well as with eucalypts was a massive reproductive effort after they suffered insect attack or disease. When adults were stressed and close to mortality, they oftentimes flowered and fruited profusely, as a last-ditch parental effort to propagate their genes into the next generation. I could usually predict which ones were close to death because they flowered like crazy, as if flashing a message to confirm their dedication to survival of the species. After massive flowering efforts, they almost always died the following season, creating a mother tree signature on the landscape which allowed accurate prediction of mortality. I felt motherly toward my gums, so it was always bittersweet when a particularly beautiful tree staged an enormous flowering event, signaling the imminent end of its life.
Despite the distractions in everyday life, I moonlighted working on canopy data, which clearly confirmed that the massive defoliation events by Christmas beetles, sawfly larvae, and a few other herbivores ultimately led to massive mortality. The insect attacks were the ultimate last straw in a chain of environmental stresses. During that decade, climate scientists announced that Australia was becoming hotter and drier, and in the outback, we witnessed those environmental extremes culminated by insect outbreaks. Soils were not changed, pollution was not part of the equation, nor had significant clearing on local farms occurred for many decades. Nothing else was glaringly obvious except a double whammy of heat and drought stimulating major insect outbreaks. With defoliation levels of up to 300 percent annual leaf area loss (meaning three flushes eaten by insects per year), the poor trees had no chance. Christmas beetles, the major culprit, thrived under rural pasture conditions and they destroyed both roots and leaves, a scenario almost like “The House That Jack Built.” When farmers thinned pasture trees, less foliage remained for beetles to eat. With fewer nesting sites, the birds that otherwise ate the beetles disappeared. When adult beetles ate leaves on a fewer number of remaining gums, they ate proportionally more, so those individual trees died, and livestock huddled under the ever-shrinking canopy shade. Those sheltering sheep and cattle then saturated the soil with nitrogen via their waste, creating ideal conditions for the next generation of beetle grubs. More larvae hatched to consume a depleting supply of roots and leaves. Ultimately, the increased populations of beetles (both grubs and adults) led to the death of the last remaining trees.
I was glad our findings pinpointed the underlying cause of dieback, and that it was insects, not that charismatic canopy marsupial. What a great day for the koalas, exonerated of all guilt; these furry herbivores did not cause tree deaths as rumored by some graziers. Having had the privilege of encountering koalas throughout my arboreal activities, I felt a special bond to these vegetarians. Their fondness for leaves paralleled mine, and even more so because they not only lived and breathed in the treetops, but they also exclusively ate gum foliage, consuming approximately 400 grams (14 ounces) of leaves each day. On several occasions, I actually patted a koala on its butt, since it was so sluggish after a salad bar feast and did not find my presence threatening. Koalas are now listed as a vulnerable species by the International Union for Conservation of Nature (IUCN). The 2020 fires not only decimated its populations, but also destroyed its canopy habitat. It will require decades to restore eucalypts into adulthood for koala habitats, and successful landscape restoration will need the exclusive species that koalas prefer, including Eucalyptus microcorys, E. camaldulensis, and E. tereticornis. Koalas are great climbers, and I was honored to share the treetops with this largest of arboreal marsupials.
