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The role of tree species diversity in drought resistance of oak and beech sapling

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The role of tree species diversity in drought resistance of oak and

beech saplings

Md Masudur Rahman

1, 3

, Kris Verheyen

2

& Monique Carnol

1

Changes in precipitation patterns due to climate change are most likely to expose European forests to drought during the growing season. It has been suggested that stands of higher tree species diversity might be more resistant and resilient to stress compared to monocultures. In this study, we will investigate whether oak and beech sapling performances and ecosystem functions are more resistant to growing season drought when planted in mixed stands.

Study questions:

Can species mixtures improve oak and beech sapling performances

under drought conditions?

What are the mechanisms underlying ecosystem functioning and

sapling performances in mixed species stands subjected to drought?

 Location:15 plots of Zedelgem (Fig. 2)

 Drought duration: April – September, 2015 & 2016

 Target measurements: Both aboveground (study 1) and belowground

parameters (study 2)

Study 1: Aboveground performances of oak and beech saplings in

species mixtures and under drought stress

Figure 2: FORBIO Experimental sites and layout of the Zedelgem site. Detailed plantation design of a 4 species mixed plot is also shown. For details- Verheyen et al. 2013. Plant

Eco. & Evo. 146(1): 26-35 or http://www.treedivbelgium.ugent.be/pl_forbio.html

Study-2: Soil microbial properties and soil biogeochemical

processes in species mixtures and under drought stress

Following parameters will be measured for oak and beech saplings

FORBIO Experimental sites

Background

0-10 cm

0-5 cm 5-10 cm

 Ion-exchange resin bags will

be buried in soil to analyse

in situ NH4+ and NO

3

-availability.

 Green and rooibos tea will

be buried and analysed to

calculate Tea bag index (TBI) (Keuskamp et al. 2013)

Resin & tea bag

Soil moisture Soil pH

Soil organic matter (SOM) content Basal respiration

N mineralization and nitrification Soil microbial biomass (C & N)

Metabolic diversity of bacteria

Target parameters

Sampling time: April & September, 2015 & 2016

1 University of Liège, Laboratory of Plant and Microbial Ecology, Botany, B22, Boulevard du Rectorat 27, 4000 Liège, Belgium. 2 Ghent University, Department of Forest and Water Management, Forest & Nature Lab, Geraardsbergsesteenweg 267, 9090 Gontrode, Belgium. 3 Sylhet Agricultural University, Faculty of

Agriculture, 3100 Sylhet, Bangladesh. Email: mmrahman@ulg.ac.be

Figure 4: Different soil biogeochemical and microbial properties will be measured in 0-10 cm soils. (Keuskamp et al. 2013. Methods in Eco. & Evo. 11(4):

1070-1075)

Plant and Microbial Ecology Botany, B22. University of Liege 4000 Liege, Belgium

Figure 1: Oak and beech sapling performance in diverse stands and under drought condition will be investigated in this study.

 This study will explore underlying mechanisms of ecosystem

functioning under drought stress.

 Our results will lead to better understanding of the link between tree

species diversity and oak and beech sapling performances under drought conditions

Perspectives

Acknowledgement:

The study is financed by the Belgian Science Policy, BELSPO, under the BRAIN-be program.

Planting details of Zedelgem site

Species pool : Betula pendula, Fagus sylvatica, Pinus sylvestris, Tilia cordata and Quercus robur

Diversity level : 1, 2, 3 & 4 species

Planting design : 3 × 3 monoculture patches in a checker board design Density : 784 trees in a plot (42m × 42 m); Plant to plant: 1.5 m Planting year : 2009-2010

Precipitation manipulation

Figure 3: Sketch of a 3m×3m rainout shelter. The frame will be made of wood and about 50% rainfall will be cut off by PVC gutters.

Plant height and diameter

Leaf traits and nutrient status

Leaf area (LA)

Specific leaf area (SLA)

Leaf dry matter content (LDMC) Leaf toughness

Chlorophyll a (chl.a) fluorescence Leaf C/N ratio

Leaf C, N & P content

Pests and pathogens damage

Branch and shoot damage Defoliation

Crown discoloration

Time of measurements:

Leaf and crown: June-July of each year.

Height and diameter: Apr., Sept. 2015 & Sept. 2016.

 12 rainout shelters and

12 control plots for oak and beech target trees.

Will be replicated 3 times FORBIO (FORest BIOdiversity & ecosystem

functioning) plantation sites

Growth & development Litter decomposition

Pest and pathogen damage Biogeochemical processes

Leaf traits Microbial biomass & functioning

Biomass production Nutrient cycling

Ecosystem response Growing season drought

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