by Noam Ross, 02 July 2012
As I begin to put together material for my thesis proposal, I’m collecting literature on regime shifts in forest ecosystems. I’m interested in the time scale of regime shifts, and how they compare with the time scale of stand dynamics (typically decades), which are the dominant time scale in forestry economics.
Here is a preliminary set of examples and citations. I’ve also created a Mendeley group with the papers I’m collecting for this topic. What other examples do people know of? Leave your thoughts in the comments!
Pests and Disease
Ludwig et al. (1978) modeled outbreaks of the spruce budworm, which occur every several decades and result in large-scale forest mortality. Budworm populations slowly increase as the forest matures and provides greater resources. Periods of warm dry weather can result in budworm numbers large enough to escape the predation of birds, and then large outbreaks occur. More on this at the Resilience Alliance
Raffa et al. (2008) has a pretty good overview of threshold processes involved in bark beetle outbreaks. One of the key threshold processes that results in regime shift is the interaction between host physiology and beetle aggregation (Berryman et al. 1984). Nelson and Lewis (2008) was able to determine this threshold through explicit modeling of tree physiology. See also Okland and Bjø rnstad (2006).
Sudden oak death
Sudden oak death, caused by the water mold Phytophthora ramorum, may exhibit a host-density threshold in its dynamics. When tanoak hosts (Notholithocarpus densiflorus), exceed a critical density (~8% of stems), outbreak may occur and result in elimination of tanoak (Cobb et al. 2012).
Drought in piñon forests
Positive feedbacks between drought stress and bark beetle populations (McDowell 2011) can lead to sudden piñon die-offs following periods of drought, which can result in long-term shifts in forest composition. Allen and Breshears (1998) documented drought-induced shifts from ponderosa forest to piñon-juniper woodland in the great basin area, and similar shifts from piñon to juniper have occurred following the 2002-2003 drought (Mueller et al. 2005, Breshears et al. 2005).
Forest and savanna as alternative stable states
There’s lots of literature about the feedbacks that maintain savannas and control the forest-savanna ecotone and evidence that they represent alternative stable states (Sternberg 2001). Staver et al. (2011) and Staver and Levin (2012) show empirical and modeling evidence that, in areas with medium levels of precipitation, forest and savanna are alternative regimes maintained by fire feedbacks. Fire spreads over open grassy areas, so fire areas with greater grass cover suppresses tree regeneration, while fire is less likely to spread over a critical density of forested area. (See also Baudena and Rietkerk (2012).)
North American forest-prairie transition:
As the North American glaciers retreated ~8000 years ago, some areas appear to have responded to the gradual shift in climate with rapid transitions from forest to prairie, as documented by Williams (2009, 2010, 2011).
Logging Fire Regime changes
Lindenmayer et al. (2011) describe positive feedbacks in mountain ash Forests of Southeastern Australia, where younger forest burns at much greater severity than older forest. Increased disturbance frequency due to logging has resulted in more of these young stands, and greater landscape connectivity between them, resulting in a regime shift to more frequent fires. The authors call this landscape-scale socio-ecological regime shift a “landscape trap”.
Rietkerk and van de Koppel (2008) review work by Hiemstra (2002, 2006) on “ribbon forests” in Wyoming, where alternate forested and non-forested areas form because snow accumulates more in non-forested areas, killing seedlings.
P availability and soil degradation
Lawrence et al. (2007) describe alternative stable states in tropical forest due to P limitation. Mature primary forest traps dust-borne P in the canopy and has lower leaching losses than secondary forest. Deforestation, cultivation, and fallow reduces soil P and replaces primary forest with secondary, resulting in long-term P declines.
This is on a much smaller scale, but there’s hysteresis in the pressure-transport relationship in woody plant xylem (Sperry et al. 2002)
(All of these are in in the Mendeley group)
Allen, C. D., and D. D. Breshears. 1998. Drought-induced shift of a forest-woodland ecotone: rapid landscape response to climate variation.. Proceedings of the National Academy of Sciences of the United States of America 95:14839–42.
Baudena, M., and M. Rietkerk. 2012. Complexity and coexistence in a simple spatial model for arid savanna ecosystems. Theoretical Ecology.
Berryman, A. A., N. C. Stenseth, and D. J. Wollking. 1984. Metastability of forest ecosystems infested by bark beetles. Research in Population Ecology 26:13–29.
Breshears, D. D., N. S. Cobb, P. M. Rich, K. P. Price, C. D. Allen, R. G. Balice, W. H. Romme, J. H. Kastens, M. L. Floyd, J. Belnap, J. J. Anderson, O. B. Myers, and C. W. Meyer. 2005. Regional vegetation die-off in response to global-change-type drought.. Proceedings of the National Academy of Sciences of the United States of America 102:15144–8.
Cobb, R. C., J. a. N. Filipe, R. K. Meentemeyer, C. a Gilligan, and D. M. Rizzo. 2012. Ecosystem transformation by emerging infectious disease: loss of large tanoak from California forests. Journal of Ecology.
Hiemstra, C. A., G. E. Liston, and W. A. Reiners. 2002. Snow Redistribution by Wind and Interactions with Vegetation at Upper Treeline in Medicine Bow Mountains, Wyoming, U.S.A.. Arctic, Antarctic, and Alpine Research 34:262–273.
Hiemstra, C. a, G. E. Liston, and W. a Reiners. 2006. Observing, modelling, and validating snow redistribution by wind in a Wyoming upper treeline landscape. Ecological Modelling 197:35–51.
Lawrence, D., P. D’Odorico, L. Diekmann, M. DeLonge, R. Das, and J. Eaton. 2007. Ecological Feedbacks following Deforestation Create the Potential for a Catastrophic Ecosystem Shift in Tropical Dry Forest. Proceedings of the National Academy of Sciences of the United States of America 104:20696–20701.
Lindenmayer, D. B., R. J. Hobbs, G. E. Likens, C. J. Krebs, and S. C. Banks. 2011. Newly discovered landscape traps produce regime shifts in wet forests.. Proceedings of the National Academy of Sciences of the United States of America 108:15887–91.
Ludwig, D., D. D. Jones, and C. S. Holling. 1978. Qualitative Analysis of Insect Outbreak Systems: The Spruce Budworm and Forest. The Journal of Animal Ecology 47:315.
McDowell, N. 2011. Mechanisms linking drought, hydraulics, carbon metabolism, and vegetation mortality.. Plant physiology 155:1051–1059.
Mueller, R. C., C. M. Scudder, M. E. Porter, R. Talbot Trotter, C. a Gehring, and T. G. Whitham. 2005. Differential tree mortality in response to severe drought: evidence for long-term vegetation shifts. Journal of Ecology 93:1085–1093.
Nelson, W. A., and M. A. Lewis. 2008. Connecting host physiology to host resistance in the conifer-bark beetle system. Theoretical Ecology 1:163–177.
Okland, B. rn, and O. N. Bjø rnstad. 2006. A resource-depletion model of forest insect outbreaks.. Ecology 87:283–90.
Raffa, K. F., B. H. Aukema, B. J. Bentz, A. L. Carroll, J. a Hicke, M. G. Turner, and W. H. Romme. 2008. Cross-scale Drivers of Natural Disturbances Prone to Anthropogenic Amplification: The Dynamics of Bark Beetle Eruptions. BioScience 58:501.
Rietkerk, M., and J. van de Koppel. 2008. Regular pattern formation in real ecosystems.. Trends in ecology & evolution 23:169–75.
Sperry, J. S., U. G. Hacke, R. Oren, and J. P. Comstock. 2002. Water deficits and hydraulic limits to leaf water supply.. Plant, cell & environment 25:251–263.
Staver, A. C., and S. A. Levin. 2012. Integrating Theoretical Climate and Fire Effects on Savanna and Forest Systems. The American Naturalist:1–14.
Staver, a. C., S. Archibald, and S. Levin. 2011. Tree cover in sub-Saharan Africa: rainfall and fire constrain forest and savanna as alternative stable states.. Ecology 92:1063–72.
Sternberg, L. D. S. L. 2001. Savanna-Forest Hysteresis in the Tropics. Global Ecology and Biogeography 10:369–378.
Williams, J. W., J. L. Blois, and B. N. Shuman. 2011. Extrinsic and intrinsic forcing of abrupt ecological change: case studies from the late Quaternary. Journal of Ecology 99:664–677.
Williams, J. W., B. Shuman, P. J. Bartlein, N. S. Diffenbaugh, and T. Webb. 2010. Rapid, time-transgressive, and variable responses to early Holocene midcontinental drying in North America. Geology 38:135–138.
Williams, J. W., B. Shuman, and P. J. Bartlein. 2009. Rapid responses of the prairie-forest ecotone to early Holocene aridity in mid-continental North America. Global and Planetary Change 66:195–207.