A rapid warming in Himalayas is predicted to increase plant upper distributional limits, vegetation cover and abundance of species adapted to warmer climate. We explored these predictions in NW Himalayas, by revisiting uppermost plant populations after ten years (2003–2013), detailed monitoring of vegetation changes in permanent plots (2009–2012), and age analysis of plants growing from 5500 to 6150 m. Plant traits and microclimate variables were recorded to explain observed vegetation changes. The elevation limits of several species shifted up to 6150 m, about 150 vertical meters above the limit of continuous plant distribution. The plant age analysis corroborated the hypothesis of warming-driven uphill migration. However, the impact of warming interacts with increasing precipitation and physical disturbance. The extreme summer snowfall event in 2010 is likely responsible for substantial decrease in plant cover in both alpine and subnival vegetation and compositional shift towards species preferring wetter habitats. Simultaneous increase in summer temperature and precipitation caused rapid snow melt and, coupled with frequent night frosts, generated multiple freeze-thaw cycles detrimental to subnival plants. Our results suggest that plant species responses to ongoing climate change will not be unidirectional upward range shifts but rather multi-dimensional, species-specific and spatially variable.

Questions (1) How do seres differ with respect to vegetation changes? (2) What are the directions of succession? (3) How do species numbers change? (4) How do target species, i.e. those typical of natural and semi‐natural vegetation, participate in succession? (5) Are spontaneously developed successional stages acceptable from the point of view of ecosystem restoration? Location Extracted peatlands, bulldozed sites in forests destroyed by air pollution, an emerged bottom of a water reservoir, corridors of former Iron Curtain, artificial fishpond islands and barriers, sedimentary basins, spoil heaps from mining, stone quarries, forest clearings, road verges, sand and gravel‐sand pits, ruderal urban sites, river gravel bars and abandoned arable fields, located in various parts of the Czech Republic in Central Europe. Methods Phytosociological relevés were recorded in 10–25 m2 plots located in the centre of representative successional stages defined by their age, ranging from 1 to 100 yrs. In total, we obtained 2392 vegetation samples containing 951 species. We performed DCA ordination to compare 19 seres. Desirable target species were considered as those representing (semi)‐natural vegetation and all Red List species. Results The seres studied are more similar in their species composition in the initial and early stages, in which synathropic species prevail, than in the later stages when the vegetation differentiates. This divergence is driven mainly by local moisture conditions. In most cases, succession led to woodland, which usually established after ca. 20 yrs. In very dry or wet places (with limited presence of woody species) open vegetation developed, often highly valuable from the restoration and conservation point of view. The total number of species and the number of target species increased in the majority of seres with successional age. Conclusions The vegetation in the sites studied formed a continuum along a moisture gradient and by successional age. The individual seres largely overlapped in their species composition; the sere identity was not significant. Spontaneous succession usually proceeded towards woodland, except at very dry or wet sites, and generally appeared to be an ecologically suitable way of ecosystem restoration of disturbed sites because target species became dominant over time.

Linking diversity to biological processes is central for developing informed and effective conservation decisions. Unfortunately, observable patterns provide only a proportion of the information necessary for fully understanding the mechanisms and processes acting on a particular population or community. We suggest conservation managers use the often overlooked information relative to species absences and pay particular attention to dark diversity (i.e., a set of species that are absent from a site but that could disperse to and establish there, in other words, the absent portion of a habitat-specific species pool). Together with existing ecological metrics, concepts, and conservation tools, dark diversity can be used to complement and further develop conservation prioritization and management decisions through an understanding of biodiversity relativized by its potential (i.e., its species pool). Furthermore, through a detailed understanding of the population, community, and functional dark diversity, the restoration potential of degraded habitats can be more rigorously assessed and so to the likelihood of successful species invasions. We suggest the application of the dark diversity concept is currently an underappreciated source of information that is valuable for conservation applications ranging from macroscale conservation prioritization to more locally scaled restoration ecology and the management of invasive species.