Objectives of this research were to determine the effect of altered hydrology on species composition and radial growth of trees in floodplain forests of the Lower Kaskaskia River. The Carlyle Dam caused significant changes in hydrology below the site of installation. Flood frequency and duration at a site 6.4 km below the dam was significantly reduced. Flood frequency was more variable at the site 6.4 km below the dam prior to dam installation. Post-dam flood frequency and duration were related to overstory and midstory species composition for all sites, whereas pre-dam hydrology was not related. This indicates that the current species composition has adjusted to post-dam river hydrology. Medium to high post-dam mean annual flood frequency and flood duration, were related to Acer negundo/Acer saccharinum, Acer saccharinum , and Acer saccharinum/Fraxinus pennsylvanica overstory assemblages. Low to medium post-dam mean annual flood frequency and flood duration were related to Betula nigra/Ulmus americana and Celtis occidentalis overstory assemblages. The overstory stratum could potentially succeed to Celtis occidentalis, a shade tolerant species dominant in the midstory strata if current conditions continue. Increasing % clay was related to Acer negundo/Acer saccharinum, Acer saccharinum , and Acer saccharinum/Fraxinus pennsylvanica overstory assemblages. Increasing % sand was related to Betula nigra/Ulmus americana and Celtis occidentalis overstory assemblages. Soil texture was not significantly related to midstory species composition. Increasing Quercus palustris basal area was related to increasing pre-dam flood duration, and no post-dam Quercus spp. relationships to hydrology were found. Significant relationships of radial growth to flood and climate variables were found, although variables were not always related in the same manner to radial growth. Generally, the relationships of climate and flood factors were different after dam installation than before. The Carlyle Dam has altered hydrology and changed tree species composition and radial growth along the Lower Kaskaskia River. Further research concerning the central floodplain forest is needed at the landscape scale to address the consequences of hydrologic alterations throughout our large river systems.

Of all the outputs of forests, water may be the most important. Streamflow from forests provides two-thirds of the nation's clean water supply. Removing forest cover accelerates the rate that precipitation becomes streamflow; therefore, in some areas, cutting trees causes a temporary increase in the volume of water flowing downstream. This effect has spurred political pressure to cut trees to increase water supply, especially in western states where population is rising. However, cutting trees for water gains is not sustainable: increases in flow rate and volume are typically short-lived, and the practice can ultimately degrade water quality and increase vulnerability to flooding. Forest hydrology, the study of how water flows through forests, can help illuminate the connections between forests and water, but it must advance if it is to deal with today's complexities, including climate change, wildfires, and changing patterns of development and ownership. This book identifies actions that scientists, forest and water managers, and citizens can take to help sustain water resources from forests.

Trees are among the longest-living organisms. They are sensitive to extreme climatic events and document the effects of environmental changes in form of structural modifications of their tissues. These modifications represent an integrated signal of complex biological responses enforced by the environment. For example, temporal change in stem increment integrates multiple information of tree performance, and wood anatomical traits may be altered by climatic extremes or environmental stress. Recent developments in preparative tools and computational image analysis enable to quantify changes in wood anatomical features, like vessel density or vessel size. Thus, impacts on their functioning can be related to climatic forcing factors. Similarly, new developments in monitoring (cambial) phenology and mechanistic modelling are enlightening the interrelationships between environmental factors, wood formation and tree performance and mortality. Quantitative wood anatomy is a reliable indicator of drought occurrence during the growing season, and therefore has been studied intensively in recent years. The variability in wood anatomy not only alters the biological and hydraulic functioning of a tree, but may also influence the technological properties of wood, with substantial impacts in forestry. On a larger scale, alterations of sapwood and phloem area and their ratios to other functional traits provide measures to detect changes in a tree’s life functions, and increasing risk of drought-induced mortality with possible impacts on hydrological processes and species composition of plant communities. Genetic variability within and across populations is assumed to be crucial for species survival in an unpredictable future world. The magnitude of genetic variation and heritability of adaptive traits might define the ability to adapt to climate change. Is there a relation between genetic variability and resilience to climate change? Is it possible to link genetic expression and climate change to obtain deeper knowledge of functional genetics? To derive precise estimates of genetic determinism it is important to define adaptive traits in wood properties and on a whole-tree scale. Understanding the mechanisms ruling these processes is fundamental to assess the impact of extreme climate events on forest ecosystems, and to provide realistic scenarios of tree responses to changing climates. Wood is also a major carbon sink with a long-term residence, impacting the global carbon cycle. How well do we understand the link between wood growth dynamics, wood carbon allocation and the global carbon cycle? Papers contribution to this Research Topic will cover a wide range of ecosystems. However, special relevance will be given to Mediterranean-type areas. These involve coastal regions of four continents, making Mediterranean-type ecosystems extremely interesting for investigating the potential impacts of global change on growth and for studying responses of woody plants under extreme environmental conditions. For example, the ongoing trend towards warmer temperatures and reduced precipitation can increase the susceptibility to fire and pests. The EU-funded COST Action STREeSS (Studying Tree Responses to extreme Events: a SynthesiS) addresses such crucial tree biological and forest ecological issues by providing a collection of important methodological and scientific insights, about the current state of knowledge, and by opinions for future research needs.

Southeastern floodplain forests are species-rich ecosystems that respond to dynamic interactions between disturbance and hydrologic regimes. Large-scale natural disturbances such as hurricanes influence forest composition and structure not only by damaging and killing overstory trees, but also by altering environmental conditions on the forest floor. In this dissertation, I examined how the composition and structure of floodplain forest ecosystems are regulated by these disturbances, with a particular emphasis on understanding how large woody vines interact with natural disturbances in floodplain forest ecosystems. Lianas are a long-neglected aspect of floodplain forests that influence tree mortality, recruitment, and growth rates and may be responding to environmental changes. Long-term studies of forest dynamics in the Congaree National Park and the Savannah River floodplains in South Carolina, U.S.A., provide ideal settings to study the interactions of hydrologic and disturbance regimes in species-rich forests with a significant large woody vine component.