Biodiversity reserve networks

With data of the Swiss dry grassland inventory I investigate how (1.) threatened species can be protected better, how (2.) the quality of the reserve network can be maintained under global change, and how (3.) connectivity between biotopes can be optimised.

dry grassland at Merishausen (SH) am Randen. Photo: TWW project (BAFU)

We have presented the first topic at the conference “Monitoring the effectiveness of nature conservation“ (Abstracts: http://www.wsl.ch/publikationen/pdf/8062.pdf). And I give here the abstract of my contribution entitled “How monitoring of nature conservation policy drives dynamic reserve selection of the dry grassland reserve network of Switzerland”:

“The dry grassland (DG) inventory of Switzerland consists of 3’143 sites with a total area of 237 km2 [1]. A preliminary evaluation of the inventory by the federal administration suggests that species-specific conservation aspects and the landscape matrix between the DG patches are currently not represented adequately. On a political level we discuss how the framework of dynamic reserve selection could be embedded in a strategic controlling system to ameliorate reserve selection. On a planning level, we propose a solution to optimise the existing reserve network with respect to individual species and landscape-scale conservation. In the draft of the ordinance to the DG inventory, areas of preference (Vorranggebiete) have been proposed as a promising new implementation tools. Areas of preference allow to flexibly adapt a reserve selection network to satisfy political and ecological goals. We used the connectivity measure developed for DG evaluation to link the DG data with a coarsely grained floristic database [2] to identify appropriate DG clusters. Subsequently, we applied a set covering framework to find optimal floristic mapping units, and a fuzzification operator to contain extend the little concise results delivered by the set covering algorithm so that they may be used by decision makers.”

[1] Eggenberg, Stefan; Dalang, Thomas; Dipner, Michael; Mayer, Cornelia. (2001). Cartography and evaluation of dry grasslands sites of national importance. Technical report. Swiss Agency for the Environment, Forests and Landscape. Berne. (Internet: http://www.bafu.admin.ch/publikationen, Search term „Dalang“)

[2] Welten, Max; Sutter, Ruben. (1982-1994). Verbreitungsatlas der Farn- und Blütenpflanzen der Schweiz. Birkhäuser. Basel.

Respective to the second topic we have estimated how much compensation is needed if dry grassland area get lost. A publication is submitted to “Biological Conservation”. We give here the draft of the abstract.

“Dalang, Thomas and Hersperger, Anna M. How much compensation do we need? Replacement ratio estimates for Swiss dry grassland Biotopes. Development pressure on reserve networks in densely populated countries may lead to the decision to allow for replacement compensation. Replacement ratios used for specifying replacement compensation are usually based on expert judgment. In contrast, we propose a method to estimate replacement ratios based on the set covering framework. The method is applied to presence-absence data of vascular plants of the dry grassland inventory of Switzerland. For the replacement of 60% of a patch's high conservation value species by the same vegetation type ("in-kind" compensation), the estimated replacement ratios are <5 for most vegetation types. These ratios are comparable with replacement ratios usually used in practice. Our replacement ratio estimates for replacement by another vegetation type ("out-of-kind" compensation) are considerable higher than proposed by the literature. For oligotroph dry grassland associations, the replacement rations are extremely high, so that these associations have to be considered irreplaceable. The estimated replacement ratios provide a good starting point for designing compensation measures for unavoidable losses in a reserve system. However, additional biodiversity conservation goals should be considered when designing replacement compensation in practice.”

Concerning the third topic, I investigate with a metapopulation model, how the connectivity in biodiversity reserve networks can be optimised. The results will be useful to ameliorate the chance of long-time survival for butterfly populations in dry grassland hotspots.