**About the Editor**

**Laszlo Erdos** graduated from the University of Szeged (Hungary) as a biologist in 2005. He earned his PhD in vegetation ecology at the University of Pecs (Hungary). His main area of ´ interest is the vegetation ecology of Eurasian forest-steppes. Currently, he is a research fellow at the Centre for Ecological Research (Vacr ´ at´ ot) and at the University of Debrecen (Debrecen). He also ´ serves as visiting lecturer at the Eotv ¨ os Lor ¨ and University (Budapest). ´

#### **Preface to "Spatial Heterogeneity of Forest-Steppes"**

Situated between the closed-canopy forests and the open steppes, forest-steppes feature a highly complex mosaic of woody and herbaceous habitats. Though forest-steppes exits in North and South-America, the largest forest-steppes are found in Eurasia, where they extend as an almost continuous belt from the Carpathian Basin in Eastern Central Europe to the Far East in China and Russia. Despite its tremendous biogeographical, ecological and even economic importance, the forest-steppe zone has received surprisingly little scientific attention. As forest-steppe landscapes are composed of a high variety of different forest, scrub and grassland communities and the ecotones among them, spatial heterogeneity is a key issue if we are to understand how forest-steppe ecosystems work and how they may react to environmental changes at the local, regional, and global scales.

Forest-steppes exist in a transitional semi-humid to semi-arid climate that enables the long-term coexistence of forests and grasslands, as these have roughly equal chances to develop. The competition outcome at every given site depends on minor differences in terrain, soil and microclimate characteristics. Once established, grassland species probably modify the environment to favor the continued existence of the grassland patch, while trees and shrubs support the persistence of woody vegetation. This seems to stabilize forest-steppe mosaics, though modifications in climate, herbivore pressure or fire frequency and intensity may alter the balance. Unfortunately, it is not known how strong these feedbacks are, thus we do not know if and where the current patterns are able to resist natural and anthropogenic changes.

Forest-steppes host exceptional taxonomic diversity from local to landscape to regional scales. In addition, they harbor a large number of rare, nationally protected, and internationally threatened species. Moreover, the functional diversity of forest-steppes is very high, with a large variety of life-forms.

Forest-steppes provide us with a number of vital ecosystem services, including a large carbon sequestration capacity, protection from soil erosion, and aesthetic value.

Unfortunately, large forest-steppe areas, especially in the most populous regions, have been destroyed and replaced with (mostly non-native) tree plantations or arable fields, while the remaining near-natural areas are threatened by the spread of invasive species, fragmentation, and overexploitation. Thus, preserving forest-steppe ecosystems presents a grea<sup>t</sup> challenge to conservationists. May we hope that a better understanding of this unique ecosystem will contribute to its more efficient conservation.

> **Laszlo Erdos** *Editor*
