Agri-Environmental Schemes and Grassland Biodiversity: Another Side of the Coin

In this paper part of the existing Agri-Environmental Schemes (AES) of the European Union are evaluated by using data on county level instead of applying field studies. The attempt is made to disentangle the effects of AES on land management practice as well as land use on biodiversity. It is argued that subsidies as AES should promote environmental-friendly land use which, in turn, should lead to biodiversity conservation. First results show that AES promotes ecological land use rather than extensive agricultural practice. Furthermore, AES is predominantly allocated in biodiversity rich counties and not in counties with low biodiversity which should be enhanced. Furthermore, no clear evidence is so far found, that land use practice is improving the biodiversity status.AES effectiveness, biodiversity, policy evaluation

About least-squares type approach to address direct and controllability problems

- We discuss the approximation of distributed null controls for partial differential equations. The main purpose is to determine an approximation of controls that drives the solution from a prescribed initial state at the initial time to the zero target at a prescribed final time. As a non trivial example, we mainly focus on the Stokes system for which the existence of square-integrable controls have been obtained in [Fursikov \& Imanuvilov, Controllability of Evolution Equations, 1996]) via Carleman type estimates. We introduce a least-squares formulation of the controllability problem, and we show that it allows the construction of strong convergent sequences of functions toward null controls for the Stokes system. The approach consists first in introducing a class of functions satisfying a priori the boundary conditions in space and time-in particular the null controllability condition at time T-, and then finding among this class one element satisfying the system. This second step is done by minimizing a quadratic functional, among the admissible corrector functions of the Stokes system. We also discuss briefly the direct problem for the steady Navier-Stokes system. The method does not make use of any duality arguments and therefore avoid the ill-posedness of dual methods, when parabolic type equation are considered