How to Extract Climate Variability from Tree-Rings

Summary

Tree-ring climate reconstructions can be helpful to better understand past climate variability beyond instrumental records. This protocol shows how to reconstruct past climate using tree rings and meteorological instrumental records.

Abstract

Tree rings have been used to reconstruct climatological variables in many locations around the world. Moreover, tree-rings can provide valuable insights into climatic variability of the last few centuries and, in some areas, several millennia. Despite the important development, that dendrochronology has had in recent decades to study the dendroclimatic potential of a large number of species present in different ecosystems, much remains to be done and explored. In addition to this, in the last few years more people (students, teachers and researchers) around the world are interested in implementing this science to extend the timeline of climate information backwards and understand how climate has changed on scales of decades, centuries or millennia. Therefore, the objective of this work is to describe the general aspects and basic steps needed to conduct a tree-ring climate reconstruction, from site selection and field sampling to laboratory methods and data analysis. In this method's video and manuscript, the general basis in tree-ring climatic reconstructions is explained so newcomers and students can use it as an available guide into this field of research.

Introduction

Tree rings are fundamental to our understanding of how trees respond to their environment. In addition, because climate affects tree growth, trees serve as environmental gauges recording the temporal variations during their lifespan. Thus, tree rings have been valuable to reconstruct past climates far beyond any instrumental climate record.

Growth processes in roots, stems, branches, leaves, and reproductive strategies in trees are regulated by environmental factors such as water, light, temperature, and soil nutrients¹. For example, stems grow radially and the vascular cambium controls radial growth

Protocol

Before the field trips have the permission of the owners, in case of a conservation area, or the corresponding authorities. It is very important that some personnel representing the authority participate in the field work to avoid any problem.

1. Sampling strategy

1. Determining the study area
   1. Select the most appropriate sampling area based on climatic information and forest composition (forests can be highly heterogeneous; Figure 1A,B).
   2. Check that the sampling site shows evident annual climatic seasonality and inter-annual climatic variation inc....

Results

Following steps 1.1 and 1.2 of the protocol, Pinus lumholtzii B.L. Rob. & Fernald was selected for this study. Among the most important aspects that were considered, a few are as follows: It is a conifer of the genus Pinus with a wide geographical distribution and very few studies from the dendrochronological point of view; it develops in poor sites with rocky outcrops, with low water storage capacity, and its growth is limited by low water and nutritional availability, which causes slow growth rate.......

Discussion

Proxy records are natural systems that depend on the weather, which were present in the past and still exist, such as lake and marine sediments, pollen, coral reefs, ice cores, packrat middens, and tree rings, so information can be derived from them²⁴. However, from most climate-sensitive proxies, tree rings represent the proxy with the highest precision and interannual resolution, allowing the dating of climatic and ecological events to the exact year of occurrence, spanning for centuries, and so.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
ARSTAN Software			https://www.ldeo.columbia.edu/tree-ring-laboratory/resources/software
Belt Sander		Dewalt Dwp352vs-b3 3x21 PuLG	For sanding samples
Chain Saw Chaps	Forestry Suppliers	PGI 5-Ply Para-Aramid	https://www.forestry-suppliers.com/Search.php?stext=Chain%20Saw%20Chaps
Chainsaw	Stihl or Husqvarna for example	MS 660	Essential equipment for taking cross sections samples (Example: 18-24 inch bar)
Clinometer	Forestry Suppliers	Suunto PM5/360PC with Percent and Degree Scales	https://www.forestry-suppliers.com/Search.php?stext=Clinometer
COFECHA Software			https://www.ldeo.columbia.edu/tree-ring-laboratory/resources/software
Compass	Forestry Suppliers	Suunto MC2 Navigator Mirror Sighting	https://www.forestry-suppliers.com/Search.php?stext=compass
Dendroecological fieldwork programs		Programs where dating skills can be acquired or honed	http://dendrolab.indstate.edu/NADEF.htm
Diameter tape	Forestry Suppliers	Model 283D/10M Fabric or Steel.	https://www.forestry-suppliers.com/Search.php?stext=Diameter%20tape
Digital camera	CANON	EOS 90D DSLR	To take pictures of the site and the samples collected (https://www.canon.com.mx/productos/fotografia/camaras-eos-reflex)
Digital camera for microscope	OLYMPUS	DP27	https://www.olympus-ims.com/es/microscope/dp27/
Electrical tape or Plastic wrap to protect samples	uline.com		https://www.uline.com/Product/Detail/S-6140/Mini-Stretch-Wrap-Rolls/
Field format		There is no any specific characteristic	To collect information from each of the samples
Field notebook			To take notes on study site information
Gloves			For field protection
Haglöf Increment Borer Bit Starter	Forestry Suppliers		https://www.forestry-suppliers.com/Search.php?stext=Increment%20borer
Hearing protection	Forestry Suppliers	There is no any specific characteristic	https://www.forestry-suppliers.com/Search.php?stext=Hearing%20protection
Helmet	Forestry Suppliers	There is no any specific characteristic	https://www.forestry-suppliers.com/Search.php?stext=Wildland%20Fire%20Helmet
Increment borer	Forestry Suppliers	Haglof	https://www.forestry-suppliers.com/Search.php?stext=Increment%20borer
Large backpacks		There is no any specific characteristic	Strong backpack for transporting cross-sections in the field
Safety Glasses	Forestry Suppliers	There is no any specific characteristic	https://www.forestry-suppliers.com/Search.php?stext=Safety%20Glasses
Sandpaper			From 40 to 1200 grit
Software Measure J2X		Version 4.2	http://www.voortech.dreamhosters.com/projectj2x/tringSubscribeV2.html
STATISTICA	Kernel Release 5.5 program (Stat Soft Inc. 2000)		Statistical analysis program
Stereomicroscope	OLYMPUS	SZX10	https://www.olympus-ims.com/en/microscope/szx10/
Topographic map, land cover map			Obtained from a public institution or generated in a first phase of research
Tube for drawings		There is no any specific characteristic	Strong tube for transporting samples in the field
Velmex equipment	Velmex, Inc.	0.001 mm precision	www.velmex.com