Offering the appetite for the monitoring of European forests a diversified diet

Abstract

Key message Forest monitoring in Europe is turning matter of renewed political concern, and a possible role for ICP Forests health monitoring has been suggested to meet this goal (Ann For Sci 78:94, 2021). Multipurpose national forest inventory (NFI) surveys yet offer a sampling effort by two orders of magnitude greater than ICP level 1, have accomplished substantial methodological and harmonization progresses in the recent years, and therefore form a decisive contributor to future European forest monitoring incentives. Possible paths for the future development of a pan-European, comprehensive and more accurate monitoring are designed that stress a crucial need to build on the assets of the existing forest monitoring programs and favor their cooperation, in order to limit the co-existence of distinct forest monitoring processes.

A square-grid sampling support to reconcile systematicity and adaptivity in the periodic spatial survey of natural resources

“…They are also a support to organize successive hierarchical samplings in multi-phased sampling designs as shown in the French NFI case. We surmise that these grids will receive more attention in the future, with the increased diversi cation of the target populations and observational variables, echoing increased preoccupations at EU levels (Ferretti 2021, Bontemps et al 2022). In particular, the need for biodiversity monitoring in forest rises simultaneously two challenges: i) that repeated but coordinated samples need to be carried out to observe population dynamics and ii) that all observations may not be realized with the same spatial intensity, some being too expensive to be carried out on a dense network of eld plots.…”

“…Many spatial surveys of natural resources, while ensuring a constant sampling effort over time, are also periodic (Olsen et al 1999, Vidal et al 2016. The need to report on a higher frequency has also been put forward in recent debates (e.g., Bontemps et al 2022) and thereby underlines the need to ensure systematicity in the sampling at different temporal resolutions. Besides, a certain degree of adaptability of the sampling effort across space and time is highly desirable for repeated or continuous surveys, for the optimization of their sampling or for practical reasons related to the survey environment (de Gruijter et al 2006).…”

“…In view of global environmental issues, monitoring requirements tend to prioritize a high temporal frequency in a variety of surveys of natural resources and the environment (Olsen et al 1999 in the USA). The renewed interest for forest monitoring to support multifunctionality in Europe (UN EN 2021, Bontemps et al 2022) not only stresses the interest for a periodic monitoring, as implemented by most National Forest Inventory (NFI) surveys (Tomppo et al 2010), but also suggests to increase its temporal frequency, paving the way for enforcing monitoring systems operating at different time periods (van Deusen 2002). Thus, the trivial approach of measuring all sampling units from a grid sampling frame once over each monitoring period (still largely implemented in surveys such NFIs) may be abandoned in favor of a constant and systematic subsampling effort over each year of a period.…”

“…Beyond heuristic developments encountered in existing spatial surveys, this theoretical approach to adaptive spatial and temporal sampling also intends to frame the set of possible options for a larger use in surveys envisioning both high-frequency and periodic reporting. Last, we develop an original application of grid-based sampling, whereby nested grids are shown to allow gradual tuning of the sampling effort while ensuring spatial quasi-systematicity, properties that recently emerged as keys to address future needs of forest ecosystems monitoring (Bontemps et al 2022). The practical implementation of these fundaments is illustrated with a large-scale repeated survey also based on these concepts, namely the French National Forest Inventory.…”

Square‐grid sampling support to reconcile systematicity and adaptivity in periodic spatial surveys of natural populations

“…Hence, we surmise that nested square grids will receive more attention in the future with increased diversification of target populations and observational variables, echoing increased preoccupations at the EU level (Ferretti, 2021;Bontemps et al, 2022). In particular, the need for biodiversity monitoring in forests simultaneously presents two challenges: (i) repeated but coordinated sampling needs to be carried out to observe population dynamics, and (ii) not all observations may be realized with the same spatial intensity, some being too expensive to be carried out on a dense network of field plots.…”