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The Acorn Connections I Cary Institute of Ecosystem Studies Page 2 of 3 ln this Project &*crn C*n*eei!*ns ! inke Acorns are a key food for white-footed mice. The mice are key predators on Gypsy Moth pupae. When there are many acorns the mouse population increases, which keeps the moth population low. However if there are no acorns, the mouse population collapses allowing the moth population to increase. Acorns also attract white-tailed deer into oak forests to feed on acorns. The deer carry adult ticks that drop off and spend the winter in the oak forests. The next year the female ticks lay eggs that hatch into larval ticks. The larval ticks are not infected with the bacteria that cause Lyme disease, but become infected when they feed on the mice that have increased because of acorns. This means that the risk of Lyme disease can be higher in oak forests two years after a large acorn crop. Acorns are a key food for white-footed mice. The mice are key predators on Gypsy Moth pupae. When there are many acorns the mouse population increases, which keeps the moth population low. However if there are no acorns, the mouse population collapses allowing the moth population lo increase. Acorns also attract white-tailed deer into oak forests to feed on acorns. The deer carry adult ticks that drop off and spend the winter in the oak forests. The next year the female ticks lay eggs that hatch into larval ticks. The larval ticks are not infected with the bacteria that cause Lyme disease, but become infected when they feed on the mice that have increased because of acorns. This means that the risk of Lyme disease can be higher in oak forests two years after a large acorn crop. Acorns initiate other chain reactions among species (e.9., mice, chipmunks, and songbirds; see R. Ostfeld and K. Schmidt), and Gypsy Moth defoliation has many effects on the forest, including influences on nutrient cycling (see G. Lovett). Because moth defoliation reduces acorn production, understanding how moths are able to persist in the forest amidst intense predation pressure by mice has also been a recent focus of our work. This has led us to study the roles of local dispersal of moths relative to local spatial variation in mouse predation as the primary determinants of moth persistence (see B. Goodwin, E. Schauber). Recent research has shown that there are mouse hot and cold spots in the forest of varying persistence. We are now investigating how these hot and cold spots affect poths, Lyme risk and songbird nesting success. Overall, our research is trying to understand how the complexity of interactions among species - including how they vary in space and time - affects the functioning of oak forest ecosystems wlth important implications for understanding forest ecosystem health, human health and biodiversity. Fig. 1. lnteractions in eastern deciduous forests S*e*' # *dtq f*s*rdt I ny-EY3s bild* T L*XITJ [.X*rre! Lr rw** td& I {hk,n*sdm lrr , t{t * x 1+ ll \ *lisrffi Iffk*l g*J I \L* i -Ttcl* r* \ ary I .-J t w ,f}J nesting songbirds, and gypsy moth dynamics. Arrows indicate the direction of the ellect of one taxon on another. Solid lines indicate positive effects (e.9., mast production on mice), and dashed arrows indicate negative effects (e.9., gypsy moths on oak trees). From Ostfeld & Jones, ln Press. B*a fd**4*w tc; ntr rP*sBur ffii 1 *t* i { { {: I unc*nt*,y { ! *#*p influencing forest dynamics, Lyme-disease risk ("pathogens"), nesting success of some ground- fi&x Tmffiffi* {* ,TJ { % -& http://www.caryinstitute.org/science-program/research-projects/acorn-connections LLt3t2012 ilu bric-Acorn Rollercoaster Poster Due Date: 1. TASK: you are asked to create a poster that will provide the foJlowing information : a. Inforrn hikers and other visitors to Virginia's forests the DANGER YEARS for contracting LYME DISEASE b. Inform hikers and other visitors to Virginia's forests the YEARS for peak infestation of gypsy moths -You are to do so over the 10 year period (1997-2006) 2. Your poster MUST include the following: a. A LINE GRAPH indicating what happens to EACH population of organisms in EACH YEAR listed above b. The graph should include the YEARS along the X-axis and ihe approximate number of'organisms on the Y-axis. NOTE: The graph REQUiRES YOU to PREDICT what will happen based on the information in the article c. ALL 5 ORGANISMS MUST be plotted on the SAME GRAPH: 1. Deer 2. Gypsy moth 3. Tick 4. Mice 5. Acorn NOTE: Be sure to take into account the NUMBER of a specific type of organism generally found within a population. For example, there are generally lots more insects in an ecosystem compared to mammals! (I.E. THINK ABOUT PYRAMID OF NUM BERSIBIOIVTASS!) ACORHJ ROLLERCOAsTER I I + k ffi \€ Learning Experience 4 Population Pressures Date: Name: The Acorn Conneetion Ecologists: Dr. Ostfeld and Dr. Jones Instituie of Ecosystem studies, NY oregon state University, Biologist: Dr. wotff Long term study of gypsy rnoths and the white-foot mouse led to furtherltudi"r of the interactions within an oak forest and the su bsequent "acorn connection." - "Bumper Crop" means lots of acorns. The oak trees produced Iots of seeds, i.e. acorns. . -oak trees have developed a clever plan for reproduction. what is it? . For-example: First year: BumPer crop Acorns rich in Protein and fats Good seeds for Favo'i'ite food of and . So, a lot of acorns = . Second-Fifth year: poor croP List results: . . Deer in oak forest import adult ticks. The tick larvae get dropped Mouse is a host to Tick larvae get the microorganism '*spirochete" from the . Lu*u. ,olts into nymphs, nymphs molt into adulthood, adult n tick gets a ride on the " Contact with humans brings about disease This study confirms the idea that the deer are the transportation system for the infected ticks, not the weather, plant life, or any other factors. " Explain how the life cycle of the gypsy moth is connected to the acorn: April 16. 1996 Ticks and. Moths, Not Just Oaks, Linked to Acorns By LES LINE l A TANGLED cycle of events in northeastern forests that gives a reason for both Lyme disease epidemics and outbreaks of glpsy moths has been unraveled by ecologists. They have traced both events to the bumper crops of acorns that are produced every three or four years and to the r.vhite-footed mice that feed on tlem. The bumper acorn crops influence the life cycles of mice and deer as well as the Srpsy moths and the spirochetes that cause Lyme disease. Based on ttreir theory, the two ecologists, Dr. Richard S. Ostfeld and Dr. Clive G. Jories of the Institute of Ecosystem Studies in Millbrook, N.Y., predict that the glpsy moth population in the Northeast will undergo one of its periodic explosions beginning this year. Theyexpect it to build to a major defoliation in rg99 that will rival the devastating caterpillarblight of.tg79-8r unless one of the moth's natural enemies, like a fungus or parasite, intervenes. The tr,vo ecologists also warn that there will be tremendous numbers of deer tick nyrnphs, the vectors of Lyme disease, in the oak-dominated woodlands of New York and New England this spring and summer. What the two ecologists call "the acorn connection" is laid out in the May issue of the journal Bioseience in an article written by them and Dr. Jerry O. Wolff, a biologist at Oregon State University. The study's principal findings come from long-term studies of grpsy moths and white-footed mice at the Mary Flagler CaryArboretum, site of the Institute of Ecosystem Studies, and a 14-year studv by Dr. Wolff of mouse populations at the Mountain Lake Biological Station in southwestern Virginia. The forests at both sites are dominatedby oaks, which have evolved a cunning strategy for reproduction- Their acorns are rich in the proteins and fats that give them a head start over but that also make them a favorite food of mice and deer. So instead of producing large crops each year, which would foster a steady population of acorn consumers, the oaks have evolved a feast-and-famine regimen: occasional bumper crops, separated by years in which the consumers starve. otler tree seeds, "The evolutionary response of oak trees appears to have been to prod.uce such large crops of acorns that the various forest consumers are simply unable to eat them all, and some survive to become seedlings," the scientists concluded' "Trees aren't as stupid as they look," Dr. Ostfeld said' In the Virginia study, r98o, 1985, rgBB and 1989 were yeals of peak acoln production, while the bumper crops were produced at CaryArboretum in r99r and agg4' By regulartrapping, after a researchers found that white-footed. mice became most numerous in the summer or spring' bumper acorn crop but that their numbers d.ropped sharplythe following winter Except in bumper years, mice run out of stored acorns by January the oak-dominated The next actors in the drama are the white-tailed d.eer, which move into import a cargo of adult areas of the forest duringyeals of bumper acorn crops- The deer also tick larvae, each ticks, which drop offand lay eggs in the leaf litter beneath the oak trees. The with a peak the size of a pinhead, hatch the next summer, just as the woods are overrun population of their preferred host, t]}e white-footed mouse. It is from the mice, not the deer, that the ticklarvae pick up the microorganism, called a meal from the mice, spirochete, that causes LSrme disease. The ticklarvae take a single blood tlen molt a few months later'into n1'mphs. The following spring, these Lyme disease-caffjryng molt to attach themselves to mice and" other mammals, including humans. They nymphs to brush past, and the become adults in late summer; the adult ticks wait in ambush for a deer cycle begins anew. ,,Without mice, the deer ticks woutd be a nuisance," Dr. Ostfeld said, "but they would not cause illness because they hatch from eggs free of the L5'me disease agent'" have shown that the larvae By measuring the number of ticks on the forest floor, the ecologists a bumper acorn crop; they are most numerous in oak-dominated woods in the year following that peakin maple-d,ominated woods in years after poor acorn crops. That confirms the idea d"". ur" the ticks'principal transport system. "There is no evidence whatsoever that other said' factors, particuiarly weather patterns, influence tick abundance," Dr' Ostfeld woodland rodent with The spirochetes' special host, the white-footed mouse, is an appealing the mice measure six to deer-colored fur, big eyes and big ears; from to the tip of their long tail another habit that eight inches. Besides their proclivity for acorns, white-footed mice have influences the forest: a taste for gypsl moth pupae' then make cocoons Glpsy moth caterpiilars feed on oakleaves in the spring and early summer, said, are "tendel, and enter a pupal stage for about Mo weeks. The inch-long pupae, Dr. Jones they will eliminate tasty morsels,' for the mice. As long as the mice are moderately abundant, virtually all of the pupae, keeping gypsy moth populations firmly in check. years of sparse acorn crops, a But when the mouse numbers suffer their inevitable crashes, in great many pupae survive ard the moth population builds over tfre next severa-I years, reaching a peakwhen their hairy caterpillars denude entire hiilsides and damage or kill thousands of trees. At this point, Dr. Jones said, "you can't get enough mice to contool the moti.s." The wide-scale defoliation caused,by gypsy moth outbreaks has many influences on the forest and its creatures. A major impact is on the oala: defoliation may delay or even eliminate the years of bumper acorn crops. The moths may aiso reshuffle the species composition of the forest by killing the oaks, encouraging the growth of saplings from other tree species. "The oak forest system under study is exceedingly comp1ex," the ecologists said. Like the soar-and-sink mouse populations, the number of gypsy moths is also prone to sudden collapse. After caterpillars defoliate many trees, the next caterpillar generation finds that food is short and that their natural insect and fungus parasites abound- The number of moths dwindles until conditions are right for their next sugeTo test the idea that white-footed mice keep gypsy moth populations in eheck, researchers at Millbrook counted. the numbers of each in successive years. In the summer of 1993, tle mouse population was moderately high and consumed almost all the S?sy motl pupae within eight days. But few mice were around the next year, so the pupae could survive uneaten long enough to hatch into motls Dr. Robert CoIwelI, professor of ecology and evolutionary biology at the University of Connecticut in Storrq, said: "This study is-a stunning example of the importance to botl human and ecosystem health of basic research in ecology and natural history." of gpsy infestations? far, it moth So seems not. Supplying exrra L1,rne disease or the severity of gypsymoth feed to the mice in'years of poor acorn crops might minimize outbreaks, the ecologists said, butt}.e risk of tickbites would soar. Lyme disease, they said, has already resulted in "fear and distrust of nature" and has dampened the enthusiasm of many people for Does this insight into the forest's natural mechanisms suggestways to reduce the incidence enjoying tle forests. Photo: Dr. Clive G. Jones and Dr. Richard S. Osffeld of Institute ofEcosystem Studies in Millbrook, N.Y., with white-footed mouse and nesting box. (Les Line for The New York Times) (pS. Cr) Graph/Diagmm: "Of Mice and Trees" shows ttre number of mice found alive on a single five-acre plot at the Institute of Ecosystem Studies rear Millbrook, N-Y. from 1991to Lgg6. (Souree: Institute of Ecosystem Studies)(pg- C8 and Cr) . j,.. l .-,1 ''t :. I I :. .:l .,1 = ,.1 _nlI i:jl .Pl The Acorn Connections I Cary Institute of Ecosystem Studies Page 2 of 3 ln this Project &*crn C*n*eei!*ns ! inke Acorns are a key food for white-footed mice. The mice are key predators on Gypsy Moth pupae. When there are many acorns the mouse population increases, which keeps the moth population low. However if there are no acorns, the mouse population collapses allowing the moth population to increase. Acorns also attract white-tailed deer into oak forests to feed on acorns. The deer carry adult ticks that drop off and spend the winter in the oak forests. The next year the female ticks lay eggs that hatch into larval ticks. The larval ticks are not infected with the bacteria that cause Lyme disease, but become infected when they feed on the mice that have increased because of acorns. This means that the risk of Lyme disease can be higher in oak forests two years after a large acorn crop. Acorns are a key food for white-footed mice. The mice are key predators on Gypsy Moth pupae. When there are many acorns the mouse population increases, which keeps the moth population low. However if there are no acorns, the mouse population collapses allowing the moth population lo increase. Acorns also attract white-tailed deer into oak forests to feed on acorns. The deer carry adult ticks that drop off and spend the winter in the oak forests. The next year the female ticks lay eggs that hatch into larval ticks. The larval ticks are not infected with the bacteria that cause Lyme disease, but become infected when they feed on the mice that have increased because of acorns. This means that the risk of Lyme disease can be higher in oak forests two years after a large acorn crop. Acorns initiate other chain reactions among species (e.9., mice, chipmunks, and songbirds; see R. Ostfeld and K. Schmidt), and Gypsy Moth defoliation has many effects on the forest, including influences on nutrient cycling (see G. Lovett). Because moth defoliation reduces acorn production, understanding how moths are able to persist in the forest amidst intense predation pressure by mice has also been a recent focus of our work. This has led us to study the roles of local dispersal of moths relative to local spatial variation in mouse predation as the primary determinants of moth persistence (see B. Goodwin, E. Schauber). Recent research has shown that there are mouse hot and cold spots in the forest of varying persistence. We are now investigating how these hot and cold spots affect poths, Lyme risk and songbird nesting success. Overall, our research is trying to understand how the complexity of interactions among species - including how they vary in space and time - affects the functioning of oak forest ecosystems wlth important implications for understanding forest ecosystem health, human health and biodiversity. Fig. 1. lnteractions in eastern deciduous forests S*e*' # *dtq f*s*rdt I ny-EY3s bild* T L*XITJ [.X*rre! Lr rw** td& I {hk,n*sdm lrr , t{t * x 1+ ll \ *lisrffi Iffk*l g*J I \L* i -Ttcl* r* \ ary I .-J t w ,f}J nesting songbirds, and gypsy moth dynamics. Arrows indicate the direction of the ellect of one taxon on another. Solid lines indicate positive effects (e.9., mast production on mice), and dashed arrows indicate negative effects (e.9., gypsy moths on oak trees). From Ostfeld & Jones, ln Press. B*a fd**4*w tc; ntr rP*sBur ffii 1 *t* i { { {: I unc*nt*,y { ! *#*p influencing forest dynamics, Lyme-disease risk ("pathogens"), nesting success of some ground- fi&x Tmffiffi* {* ,TJ { % -& http://www.caryinstitute.org/science-program/research-projects/acorn-connections LLt3t2012