An Analysis of Vegetation Restoration on Opencast Oil Shale Mines in Estonia

Abstract

We compared four types of 30-year-old forest stands growing on spoil of opencast oil shale mines in Estonia. The stand types were: (1) natural stands formed by spontaneous succession, and plantations of (2) Pinus sylvestris (Scots pine), (3) Betula pendula (silver birch), and (4) Alnus glutinosa (European black alder). In all stands we measured properties of the tree layer (species richness, stand density, and volume of growing stock), understory (density and species richness of shrubs and tree saplings), and ground vegetation (aboveground biomass, species richness, and species diversity). The tree layer was most diverse though sparse in the natural stands. Understory species richness per 100-m 2 plot was highest in the natural stand, but total stand richness was equal in the natural and alder stands, which were higher than the birch and pine stands. The understory sapling density was lower than 50 saplings/100 m 2 in the plantations, while it varied between 50 and 180 saplings/100 m 2 in the natural stands. Growing stock volume was the least in natural stands and greatest in birch stands. The aboveground biomass of ground vegetation was highest in alder stands and lowest in the pine stands. We can conclude that spontaneous succession promotes establishment of diverse vegetation. In plantations the establishment of diverse ground vegetation depends on planted tree species.

Sandpits provide critical refuge for bees and wasps (Hymenoptera: Apocrita)

“…Bees and wasps were clearly When focusing on the more detailed characterization of habitats utilized by the bees and wasps in sandpits, it was possible to notice a significant decrease of both abundance and diversity in sandpits under reclamation and in completely reclaimed sandpits, which was even more prominent when focusing on the rare species alone (Table 5). This is in agreement with the previous observations on the other groups of organisms (Pensa et al 2004;Krauss et al 2009;Tropek et al 2010;Alday et al 2011;Baasch et al 2012;Tropek et al 2012), and argues that the spontaneous or assisted succession should be allowed at least at those sites, which are unlikely to be returned to productive agricultural or horticultural such as those at steep slopes or at the ''poor'' quality soils, where the conflict with any economic interests should be low and the nature conservation benefits prevail.…”

Responses of Soil Seed Bank and Vegetation to the Increasing Intensity of Human Disturbance in a Semi-Arid Region of Northern China

“…Due to the dramatic decreasing of soil quality in desertified land, especially in soil water and nutrients, the degradation of vascular plants and the irreversible rapid decrease of vegetation cover become the most important characteristics of desertification. In the past decades, trees and shrubs planting were traditionally employed to restore vegetation and combat desertification in North China [6], but it did not perform very well, mainly due to its high cost, low survival rate, and high water consumption [7]. A nature-based solution was considered as a cost-effective long-term solution for land degradation; it focused on improving soil quality and restoring vegetation to enhance the sustainability of the degraded land [8].…”

Geoecology of ecosystem recovery at an inactive coal mine site, New Zealand

“…In the past, most mine sites were abandoned, and natural rehabilitation processes were relied upon to develop new ecosystems on the disturbed land (Roberts et al 1981;Bradshaw 1983;Russell and La Roi 1986;Bell 2001;Prach and Pyšek 2001;Wanner and Dunger 2002). All disturbed land will develop new and sustainable ecosystems eventually, but considerable erosion and dispersal of mine site materials may take place before that occurs (Munshower 1994;Wong 2003;Pensa et al 2004). In addition, nearby human populations are becoming progressively less tolerant of long-term disturbed sites in their midst.…”

“…In addition, nearby human populations are becoming progressively less tolerant of long-term disturbed sites in their midst. Hence, rapid development of new ecosystems on mine sites is now a high priority for any mining venture, and commonly a regulatory condition imposed before mining starts (Bell 2001;Prach and Pyšek 2001;Pensa et al 2004). Nowadays, planning of the rehabilitation stage is part of the overall mine plan before the mine opens and simple steps, such as stockpiling topsoil for subsequent plant establishment, can facilitate rapid ecosystem restoration (Carroll et al 2000;Holmes 2001;Bell 2001;Pensa et al 2004).…”

“…Hence, rapid development of new ecosystems on mine sites is now a high priority for any mining venture, and commonly a regulatory condition imposed before mining starts (Bell 2001;Prach and Pyšek 2001;Pensa et al 2004). Nowadays, planning of the rehabilitation stage is part of the overall mine plan before the mine opens and simple steps, such as stockpiling topsoil for subsequent plant establishment, can facilitate rapid ecosystem restoration (Carroll et al 2000;Holmes 2001;Bell 2001;Pensa et al 2004). Planning of the rehabilitation activity can be considerably enhanced by a close knowledge of the natural processes of rehabilitation that occur on disturbed lands, because the natural processes are normally the most efficient and effective for a particular site (Russell and La Roi 1986;Holmes 2001;Bell 2001).…”