Ancient Burial Mounds Provide Safe Havens for Grassland Specialist Plants in Transformed Landscapes—A Trait-Based Analysis

Balázs Deák,Zoltán Rádai,Réka Kiss,Katalin Lukács,Zoltán Bátori,István Elek Maák,Orsolya Valkó,András Kelemen

doi:10.3389/fevo.2021.619812

Abstract

Due to the intensified land use in transformed landscapes, grassland biodiversity is often restricted to habitat fragments inadequate for arable use or for urban development. In continental parts of Eurasia, the ~600,000 ancient burial mounds (called “kurgans”) built by nomadic tribes of the steppes are amongst the most widespread landmarks providing refuge for dry grassland species. In our study by using plant functional groups and functional traits, we aimed at gaining insight into the ecological and evolutionary processes shaping the structure and the composition of assemblages of grassland specialist plant species on kurgans embedded in the agricultural landscapes of East-Hungary. As a comparison, we also studied roadside verges and pristine extensive grasslands in the same region. We found that despite their small size, due to the lack of human disturbances and high microhabitat diversity kurgans can maintain a high species richness and percentage cover of specialists, especially when compared to verges. We revealed that assemblages of specialist plants on kurgans are characterized by traits typical to terrestrial habitat islands such as self-compatibility, large seed mass and tall stature. Kurgans and extensive grasslands were characterized by higher functional diversity (both at the level of single traits and multi-trait based functional dispersion) which is probably due to the higher level of environmental heterogeneity compared to the homogeneous environment in verges.

Highlights

Land use intensification leading to the loss and fragmentation of natural habitats is considered one of the major threats to biodiversity on local, regional and global scales
Plot-level species richness and cover of specialists were high on kurgans and in extensive grasslands, whilst specialist species were underrepresented in verges (Figure 1, Supplementary Table 2)
The amount of functional space occupied by species assemblages was similar in the three studied habitat types, we found that functional dispersion was higher on kurgans and in extensive grasslands compared to verges

Summary

Introduction

Land use intensification leading to the loss and fragmentation of natural habitats is considered one of the major threats to biodiversity on local, regional and global scales. The remnants of formerly widespread natural habitats could persist within the few protected areas, and in small fragments surrounded by intensive croplands, forest plantations or urban areas (Auffret et al, 2015; Batáry et al, 2020; Deák et al, 2020a) This phenomenon is especially valid for dry grasslands often harboring extremely high herbaceous plant diversity and. It has been realized that sites with sacred, historical and cultural values, such as old cemeteries, churchyards, shrines and sacred groves, can act as important safe havens for biodiversity (Bhagwat and Rutte, 2006; Löki et al, 2019; Rath and Ormsby, 2020) These sites are often protected and managed by local people and less affected by negative land-use changes such as tilling or management intensification (Bhagwat and Rutte, 2006). Due to their cultural significance and the fact that their steep slopes hinder tilling, kurgans often preserve the last remnants of dry grassland vegetation and maintain a high diversity of grassland specialist species even in intensively used landscapes (SudnikWójcikowska et al, 2011; Deák et al, 2020a,b; Dembicz et al, 2020)

Methods

Results

Discussion

Conclusion