Mediterranean forests provide multiple challenges and opportunities to dendroecology. I will cover some of these questions by presenting three examples we have studied. These study cases include different stressors such as drought-induced dieback affecting silver fir forests, winter drought involving Scots pine stands, and defoliations caused by the pine processionary moth. Tree rings allow addressing these disturbance factors following a retrospective approach. However, I will emphasize that such observational studies must be complemented by other sources of information (e.g.
The assumption that a single dominant climatic factor (e.g. water balance or temperature) in extreme sites and locations limits tree growth allows for annually resolved climate reconstruction.
Wildfire activity in the boreal forests of Siberia has been increasing over the past 20 years in response to warming temperatures, with several extreme fire years in the past decade. While extreme fire yeas have a strong association with temperature and drought conditions, smaller human-ignited fires occur almost every year, related to agriculture and logging. To better understand the longer-term context of wildfires and fire-climate relationships of central Siberia, we developed a fire history for the Buryatia province, where we collected 25 sites of fire-scarred material throughout the
The forest biome is expected to shift geographically with anthropogenic climate change. To build species-specific, process-based models for forecasting how trees' geographic distributions will change under future climate scenarios, we see a need to combine two major, complementary sources of information on individual tree performance in response to climate variation: tree-ring and forest plot data.
The National Forest Inventory and Analysis Program (FIA) conducts a congressionally mandated repeat forest inventory implemented on all lands in the conterminous United States. Forested plots (~125,000 nationwide) are revisited on a 5- or 10-year basis for data collection. As part of baseline protocols on initial visits increment cores were collected. Cores were used for aging stands, determining potential productivity in timber forest types and to quantify growth increment.
Mountain snowpack is a critical factor for determining annual streamflow in the upper Colorado River, but other climatic factors can play an important role as well. In particular, spring temperatures appear to be increasingly important, but antecedent fall moisture and early summer rainfall may also influence flows. In the Colorado River basis, where water demand increasingly exceeds supply, water managers are interested in gaining insights on these additional climatic influences.
The southernmost European conifers forests are considered vulnerable areas to climate change. Recent climatic trends towards warmer and drier conditions across the Mediterranean Basin might render some of these populations more vulnerable to drought-induced growth decline at the southernmost limit of the species distribution and in relict forests. In addition to climate drivers, the land use changes and past management drive the growth response to climate change effects.
The tree-ring response to climate change is one of the most interesting problems in modern forest ecology. Despite the large number of papers on tree-ring response to environmental change (temperature increase, irrigation, drought, etc.) there is no reliable answer to how woody plants will respond to such change in different forest stands and biogeographic zones. The process-based tree-ring model developed by Vaganov & Shashkin ( VS-model) can be a key to answering this question.Two new principal approaches are described:
The 1970s were a period of intense activity in the Gallina heartland of north-central New Mexico. Excavations by James Mackey and Sally Holbrook and by Herb Dick documented dozens of Gallina sites and structures in the Llaves Valley alone. Unfortunately, analysis and publication did not always follow excavations, particularly in Herb Dick’s case. His untimely death in 1993 left much of his excavated material in disarray.