LTSER NETWORK ROMANIA – Covering diverse ecoregions and integrating socio-ecological systems

The Danube Delta Biosphere Reserve, located in Romania, encompasses a diverse range of ecosystems, including wetlands, waterways, lakes, and coastal areas. It covers approximately 580,000 hectares and is characterized by its low-lying
terrain, with much of it below sea level. The delta formed over thousands of years, with successive lobes extending from the original delta due to sediment deposition from the Danube River. Vegetation in the reserve includes reed
marshes, aquatic plants, and willow forests, while soils consist mainly of alluvial, gley, and histosols, emphasizing the area’s importance as a wetland. The hydrology of the delta is influenced by the Danube River’s water discharge,
with a complex network of streams and canals shaping the landscape. However, human activities such as agriculture and drainage have altered some aspects of the delta’s morphology and ecology.

The Braila Islands site, covering over 2600 km2 in Southeast Romania along a 78 km stretch of the Danube River between Harsova and Braila cities, is home to approximately 300,000 people. This socio-ecological system includes both heavily
modified ecosystems, such as the Big Island of Braila transformed into agricultural land, and natural systems like the Small Islands of Braila, which hold crucial natural and socio-economic value. The Danube River in this region
has undergone significant modifications, with embankment and regulation works affecting over 79% of the river stretch. The remaining natural floodplains are primarily found in the Small Island of Braila Natural Park and the floodplains
between riverbanks and dikes. Vegetation in the area includes deciduous native forest, wetlands, and open grasslands, with a diverse range of plant species identified. Soils consist of various types including Calcaric Fluvisol and
Haplic Phaeozem. Historically, the area contained extensive floodplains and wetlands, providing habitats for numerous species and supporting fisheries and agriculture. However, large-scale agricultural development since the 1960s
has led to the conversion of many water bodies and floodplains into crop production systems, heavily subsidized by energy. Despite this, significant wetland areas remain, including the Small Island of Braila wetlands and floodplains
along the riverbanks.

The Bucegi-Piatra Craiului site, situated in the south-central region of Romania, within the Bucegi and Piatra-Craiului Mountains of the Southern Carpathians, comprises two national parks: Bucegi NP (32,500 ha) and Piatra-Craiului
NP (13,800 ha). Designated as ILTER Sites in 2003 and later as LTER – Europe sites in 2008, these areas are renowned for their diverse vegetation, including many endemic species, and rich fauna, including endangered species like
chamois, bear, lynx, and wolf. The karst topography of the region, particularly evident in the Piatra Craiului limestone massif, features spectacular formations such as gorges, caves, ravines, and sinkholes. The geological composition
of the area comprises the Bucegi Conglomerate, a thick conglomerate-sandstone unit of Albian age, and massive limestone formations. Vegetation consists of beech, conifers, mixed forests, alpine grasslands, and herbaceous vegetation.
Hydrology is strongly influenced by erosion processes due to the geological structure, and economic activities such as overgrazing and tourism.

The Neajlov River and its catchment area, located in southern Romania, are vital components of the region’s hydrological system. With a geological composition characterized by porous rocks and diverse soil types, including Luvisols
and Chernozems, the area supports a rich ecosystem. Hydrotechnical projects implemented over decades have resulted in the creation of numerous water reservoirs, such as Gradinari and Facau, catering to various needs, including irrigation
and household water supply. Certain regions exhibit notably high surface runoff and total water yield, driven by factors like soil properties and precipitation patterns. Although variations in infiltration, and evapotranspiration
rates across the catchment, groundwater discharge remains significant, highlighting the complex hydrological dynamics of the Neajlov River basin.

The Retezat LTER site, nestled in the western Southern Carpathians, features a rich array of natural wonders. Declared a biosphere reserve in 1979, Retezat National Park is renowned for its diverse landscape, geological intricacies,
and vibrant flora. Encompassing majestic peaks and verdant forests, the park is home to over 1190 plant species, including beech, spruce, fir, and alpine pine. Its long-term research network, established in 2000, spans 11 research
plots across representative forest and alpine ecosystems; it spans both forest and alpine ecosystems. The geological makeup features granodioritic massifs, crystalline schists, and sedimentary deposits, creating a mosaic of habitats
for diverse plant life. The botanical treasures of Retezat include over 90 endemic species, contributing significantly to Romania’s plant conservation efforts. However, threats such as sheep grazing endanger delicate ecosystems,
particularly alpine pastures. Hydrologically, Retezat is characterized by an extensive network of rivers, including Lapusnicul Mare, and pristine glacial lakes like Bucura and Zanoaga, which play a crucial role in regulating river
flow. Human interventions, such as the construction of dam lakes, have altered the landscape, underscoring the need for sustainable management practices to preserve Retezat’s ecological integrity.

The Rodna-Calimani site, nestled in the northern Eastern Carpathians, comprises two national parks (Rodna Mountain National Park and Calimani National Park) and one Biosphere Reserve (Pietrosul Rodnei). Forests blanket over 50% of
the site, hosting a diverse array of species including beech, spruce, mountain pine, and fir. Notably, the Pinus cembra population is unique to the Eastern Carpathians, representing one of the region’s most iconic species. Since
2007, the site has been a hub for long-term research, focusing on climate and tree growth through continuous monitoring. Additionally, since 1976, several permanent plots have been established to study natural forest stand dynamics.
Geologically, the Rodna Mountains are predominantly composed of crystalline layers, with limestone formations fostering the development of karst landscapes and notable caves. High-altitude lakes, such as Iezer and Taurile Buhaiescului,
dot the landscape, adding to its allure. The site’s rich flora boasts over 1100 species of flowering plants, including glacial relics, with the endemic Lychnis nivalis standing as a testament to its botanical richness.