Root-surface phosphatase activity in shrublands across a European gradient: effects of warming.

Root-surface phosphatase activities were measured in natural and semi-natural shrublands across an European climatic gradient of temperature and rainfall including Wales (WL), Denmark (DK), Netherlands (NL), Hungary (HU), Italy (IT) and Spain (SP). In each site a warming experiment was conducted since 1999 or 2001 by means of passive night-time warming using reflective curtains that covered the vegetation at night. The treatments increased yearly average soil temperatures around 0. 8 degrees C in most of sites. Root-surface phosphatase activity values ranged between 56 mg PNP g(-1) h(-1) in IT and 3.5 mg PNP g(-1) h(-1) in HU. Warming had no effect on root-surface phosphatase activity across the sites and only in Hungary a slight increase was detected. Plants at Mediterranean sites (IT, SP) showed a higher root-surface phosphatase activity than plants at temperate sites (WL, NL, DK). We suggest it might be an adaptation of plant species evolved under Mediterranean climate that allows them a) to compensate in wet period for the decrease in phosphatase activity, and thus P uptake, during drought periods, and/or b) to benefit from soluble organic P flushes following the frequent drying-rewetting episodes experienced by soils in Mediterranean ecosystems.

Towards a long-term integrated monitoring programme in Europe: network design in theory and practice.

Long-term integrated monitoring is an important approach for investigating, detecting and predicing the effects of environmental changes. Currently. European freshwaters, glaciers, forests and other natural and semi-natural ecosystems and habitats are monitored by a number of networks established by different organisations. However, many monitoring programmes have a narrow focus (e.g. targeting individual ecosystems) and most have different measurement protocols and sampling design. This has resulted in poor integration of ecosystem monitoring at a European level, leading to some overlapping of efforts and a lack of harmonised data to inform policy decisions. The need for a consistent pan-European long-term integrated monitoring of terrestrial systems programme is recognised in the scientific community. However, the design of such a system can be problematic, not least because of the constraints imposed by the need to make maximum use of existing sites and networks. Based on the outcomes of the NoLIMITS project (Networking of Long-term Integrated Monitoring in Terrestrial Systems). this article reviews issues that should be addressed in designing a programme based on existing monitoring sites and networks. Four major design issues are considered: (i) users' requirements, (ii) the need to address multiple objectives, (iii) role of existing sites and (iv) operational aspects.