Implementation and application of multiple potential natural vegetation models – a case study of Hungary

Abstract

QuestionsMultiple Potential Natural Vegetation (MPNV) is a framework for the probabilistic and multilayer representation of potential vegetation in an area. How can an MPNV model be implemented and synthesized for the full range of vegetation types across a large spatial domain such as a country? What additional ecological and practical information can be gained compared to traditional Potential Natural Vegetation (PNV) estimates? Location Hungary MethodsMPNV was estimated by modelling the occurrence probabilities of individual vegetation types using gradient boosting models (GBM). Vegetation data from the Hungarian Actual Habitat Database (MÉTA) and information on the abiotic background (climatic data, soil characteristics, hydrology) were used as inputs to the models. To facilitate MPNV interpretation a new technique for model synthesis (rescaling) enabling comprehensive visual presentation (synthetic maps) was developed which allows for a comparative view of the potential distribution of individual vegetation types. ResultsThe main result of MPNV modelling is a series of raw and rescaled probability maps of individual vegetation types for Hungary. Raw probabilities best suit within-type analyses, while rescaled estimations can also be compared across vegetation types. The latter create a synthetic overview of a location's PNV as a ranked list of vegetation types, and make the comparison of actual and potential landscape composition possible. For example, a representation of forest vs grasslands in MPNV revealed a high level of overlap of the potential range of the two formations in Hungary. ConclusionThe MPNV approach allows for viewing the potential vegetation composition of locations in far more detail than the PNV approach. Rescaling the probabilities estimated by the models allows easy access to the results by making potential presence of vegetation types with different data structure comparable for queries and synthetic maps. The wide range of applications identified for MPNV (conservation and restoration prioritisation, landscape evaluation) suggests that the PNV concept with the extension towards vegetation distributions is useful both for research and applications.

Restoration prioritization for industrial area applying multiple potential natural vegetation modeling

“…In the course of the modeling, Gradient boosting models (Elith et al ) were used to relate the abiotic conditions to the observed presence of natural vegetation types. The statistical relationships identified were used to estimate presence probabilities of vegetation types as defined in the national habitat classification system (Bölöni et al ) for the whole country including areas currently devoid of natural vegetation (Somodi et al ). The same 35 ha resolution (of adjacent hexagons) was used for the predictions as the input vegetation data were available in this scale (MÉTA database; Molnár et al ).…”

“…In the course of the modeling, Gradient boosting models (Elith et al 2008) were used to relate the abiotic conditions to the observed presence of natural vegetation types. The statistical relationships identified were used to estimate presence probabilities of vegetation types as defined in the national habitat classification system (Bölöni et al 2011) for the whole country including areas currently devoid of natural vegetation (Somodi et al 2017 also on the data characteristics per vegetation type, which is an undesirable property. Habitats with few occurrences due to specific environmental requirements but not due to human intervention and widespread zonal types achieve high probabilities in absolute, but those with few occurrences due to conversion by humans have lower probabilities even where they are relatively probable compared to their own distribution.…”

“…MPNV may be estimated by expert knowledge or by automatic methods, such as predictive vegetation modeling. Such a model‐based estimation is available for Hungary for all broad vegetation types in a resolution of 35 ha hexagons (for overviews visit http://www.novenyzetiterkep.hu/node/1411; estimated values are available as a database through the gateway of the MÉTA database; Somodi et al ). The MPNV estimation can be considered as a multilayer map depicting the suitability of present conditions regarding individual vegetation types, as it formalizes on the relationship of vegetation with a synthesis of climate, hydrology, soil, and terrain variability.…”

Model‐based reconstruction of the succession dynamics of a large river floodplain

“…Despite these simplifications, the model accuracy is good. The validation of ecological models against expert‐based PNV maps in areas where the actual vegetation cannot be used because of strong anthropogenic modification is common practice (Hickler et al, ; Somodi et al, ). We chose the fuzzy approach to assess the agreement because it allowed the consideration of similarities between the vegetation communities along the successional gradient from “initial phase” to the “terminal stage” and the consideration of spatial proximity between cells.…”

Incorporation of potential natural vegetation into revegetation programmes for sustainable land management

“…Potential natural vegetation (PNV) is that which grows in a natural environment without human intervention (Tüxen, 1956). PNV could serve as a restoration reference (Loidi et al, 2010;Somodi et al, 2017;Zerbe, 1998), but there have been objections to its implementation.…”