PackageOverview.RmdThe R package medfateland has been designed to facilitate running model simulations of forest functioning and dynamics at the landscape and regional scales. The package allows executing the stand-level models available in package medfate on points and grid cells within a landscape, in either sequential or parallel computation. In addition, medfateland allows performing simulations while accounting for processes relating different spatial units.
Complete documentation on the design and formulation of the simulation models and their inputs can be found at the medfate reference book.
In previous versions of medfateland package, data structures extended those of older version of meteoland, which in turn depended by then on package sp. Current versions of medfateland (ver. > 2.0.0) use package sf (simple features) to represent spatial structures, both for inputs and outputs. Documentation and examples are given in the package of the variables that need to be represented.
Eco-hydrological processes are fundamental for the simulation models included in the medfate package. Eco-hydrological processes can be divided into local and landscape processes.
By local water balance we refer to the water balance of soils and plants within forest stands. Processes affecting soil water content include rainfall, canopy interception, infiltration and runoff, percolation and deep drainage, soil evaporation and plant transpiration.
In package medfate, the local soil water balance of
a forest is primarily used to predict forest hydrological flows and
drought stress for living plants in it; and the main simulation function
is spwb(). Package medfateland extends the
former function by allowing the simulation of soil water balance for
multiple stands distributed spatially over a given time period using
function spwb_spatial(), which makes internal calls to
spwb() on elements the spatial classes introduced above.
Function spwb_spatial_day() is analogous to the former, but
is used for the simulation of a single day, using internal calls to
function spwb_day() of medfate. Function
spwb_spatial() and its one-day counterpart may be used
to:
Changes in leaf area, plant density and biomass are key to evaluate the influence of climatic conditions on forest function and dynamics. Processes affecting annual changes leaf area and plant size are those involved water and carbon balances, as well as those affecting growth directly. Processes influencing plant water balance include those affecting soil water content, such as rainfall, canopy interception, infiltration and runoff, percolation and deep drainage, soil evaporation and plant transpiration. Carbon balance arises from the relationship between plant photosynthesis and respiration, although carbon reserves play a role in the availability of carbon for growth. Water and carbon balances are coupled through the regulation of transpiration done by stomata. Plant growth is affected by the availability of carbon (source limitation), but also by temperature and water status (sink limitation). Leaf area of plants can be severely decreased by drought stress, causing an increase in dead leaf area and affecting carbon and water fluxes.
Package medfate allows simulating carbon balance,
growth and mortality of a set of plant cohorts (competing for light and
water) in a single forest stand using function growth().
Package medfateland extends the former function by
providing function growth_spatial(), which operates on
spatial classes and makes internal calls to function
growth(). Function growth_spatial_day() is
analogous to the former, but are used for the simulation of a single
day, using internal calls to function growth_day() of
medfate. Function growth_spatial() and its
one-day counterpart may be used to:
Changes in forest structure and composition result from the interplay of natural demographic processes (growth, mortality and recruitment) and natural or anthropogenic disturbances, including the effects of forest management.
Package medfate includes function
fordyn(), which allows simulating these processes at yearly
time steps on a given forest stand, building on previous models. Package
medfateland extends the former function by providing
function fordyn_spatial(), which operates on spatial
classes and make internal calls to function fordyn(). In
addition, medfateland provides function
fordyn_scenario(), which allows performing simulations of
forest dynamics for a set of forest stands, while coordinating
management actions in the set of stands following a timber demand-based
approach, which defines the amount of wood to be cut annually for target
tree species. In addition, stands are classified into management units,
which can be associated with different silvicultural practices.
When input data is in form of continuous spatial variation of forests
over a landscape, the medfateland package allows
performing local process simulations while accounting for lateral water
transfer processes. This is done using functions
spwb_land(), growth_land() and
fordyn_land(). Three lateral water flows are considered in
medfateland:
Functions spwb_land() and growth_land() may
be used to:
Function fordyn_land() may be used to: