MATREEX

MATREEX aims to explore interactions between spatial complexity, in the form of fragmented clustered active planting, and species diversity (alpha and beta) in relation to growth, mortality and recruitment and the microclimatic conditions within plots and between, in what we call the matrix to optimize forest restoration strategies. Integrating advanced monitoring technologies, this experiment proposes to develop practical, scalable reforestation strategies that support long-term ecological sustainability grounded in ecological theory.

Overview of experimental location. Top left, Costa Rica, top right, zoomed in Limon Province area with on the Eastern side the Atlantic Ocean. Bottom, zoomed in area for the experiment. Different colored polygons represent each block/replicate. Each polygon will be subdivided in 9 subplots, each 16 x 16 meters with a core 10x10 to be measured and a 3-meter buffer zone around.

Design

The experiment starts from a pasture, remaining trees will be avoided in the placement of matrices and, if necessary, removed prior to the experiment. The experiment has two treatments: density of planting clusters (i.e. plots) with three levels and tree diversity with 3 levels (rows), applied in a full factorial, randomized block design with four blocks/replicates. Each unit of experimental treatment is called a matrix. Each is composed of 9 plots with a 10 x 10 m (0.01 ha) core and a buffer of 3 meters on all sides. Each plot will be planted with a hexagonal spaced saplings on a 2.5 m grid, for a total of approximately 65-70 trees per plot (25-30 trees per core). Plot density treatment consists of three density levels: 0 plots (no restoration), 5 or 9 plots (complete restoration) out of the 9 per matrix. Tree diversity treatment (D1-3) consists of three tree diversity levels that differ based on alpha and beta but not gamma diversity. Gamma diversity consists of five different tree species per matrix. D1 consists of monoculture plots (alpha = 1) planted with all trees of the same species within each plot but with different species among the plots from all five species available. As a result, additive (Beta_a = 4) and multiplicative (Beta_m = 5) beta diversity are maximized under this diversity treatment. D2 consists of 3 species per plot but with different combination of the 5 species among the plots (5 or 9 random combinations of 3 species selected from the 5 species depending on the plot density level), resulting in intermediate beta diversity (Beta_m = 1.7 and Beta_a = 2). D3 consists of 5 species within each plot and among plots with the same five species in each plot, resulting in the lowest beta diversity (Beta_m = 1 and Beta_a = 0). The 0-plot density level (left side margin column) consist of only one matrix as there is no diversity treatment. This results in a total of 9 matrices of approximately 0.23 ha each per block for a total of 1.6 ha per block. Each block is replicated four times and randomized for placement with respect to both elevation and distance to forest edge. Species planted are those often used in reforestation projects.

Site characteristics

	MATREEX (San Miguel)
Country	Costa Rica
Biome	tropical
Latitude	9.99
Longitude	-83.37
Soil type	Ultisol
Former land use	cattle pasture
Altitude	330-37 0m
Design	stem-wise randomisation
Plot shape	square
Plot size (m^2)	256 m²
Plant distance (m)	2.5
Number of trees planted	10000
Diversity variables	species richness
Diversity gradient	1,3,5 species
Size species pool	5
Species pool	Dipteryx oleifera Vochysia guatemalensis Terminalia amazonia Hyeronima alchorneoides Pentaclethra macroloba
Contact person	Edwin Pos Yann Hautier
Email	e.t.pos@uu.nl y.hautier@uu.nl

Research

Experimental objectives

To assess the effect of spatial configuration in a fragmented fashion based on nucleation theory (e.g. from cleared land to clustered plantings or bush islands and continuous forest) and tree species diversity (alpha and beta) on secondary succession across taxonomic groups, below and above-ground.
To evaluate the effect of these treatments on aboveground and belowground microclimate conditions (e.g. temperature, humidity, nutrient cycling etc.) towards better understanding of facilitation effect of reforestation efforts.

Theoretical objectives

To understand how disturbance influences relationships between observed and predicted macroscopic state variables such as species diversity and (total) biomass using forest inventory data from secondary rainforest with different land use history and primary rainforest (both are part of a larger research project; see below) as well as the experiment for the long-term prospects of the project.
To quantify whether restoration efforts can restore not only these quantifiable macroscopic state variables but also restore their relationships as predicted, studying not only the return of ecosystems metrics as often studied but also their relationships.

Expected outcomes

We aim to gain deeper insights into how spatial complexity and biodiversity gradients affect ecosystem processes and resilience from first principles in ecology, grounding experimental and empirical results in a strong theoretical framework.
Guide reforestation strategies by developing guidelines for optimizing reforestation practices, considering plot density and species diversity.
Promote long-term sustainability and functionality of reforested areas, contributing to mitigation and conservation in collaboration with the local community and involving the next generation of scientists in the form of student projects.

Extra information

Send an e-mail to the contact person, or explore the publications that utilized data from this experiment.

Research papers

This experiment is working hard on the first international publications