Skip to main content

 

NFDRS

Home

Goals & Objectives

Document Templates

Library

Curriculum

Incident Action Plans

Data Introduction

Fire Occurrence

Weather

GIS & NIFC AGOL

Calendar Events

FireFamilyPlus

WIMS

Links

Fuel Models

Nelson Model

Models Introduction

Growing Season Index

WFAS

Policy Docs & Agency Guidelines

Growing Season Index (GSI)

NFDRS header graphic. Decorative.

 

The Growing Season Index (GSI) In NFDRS 2016, controls live fuel moistures, replacing the 1000-hour and X1000 controls in the 1978/88 versions. The moisture bounds  (30-250 for herbaceous and 50-200 for woody shrubs) and behavior of annuals versus perennials are maintained.

nfdrs-gsi_us.png The Growing Season Index is a simple metric of plant physiological limits to photosynthesis. It is highly correlated to the seasonal changes in both the amount and activity of plant canopies. It predicts the green-up and senescence of live fuels and the influence of water stress events on vegetation. Increasing values of GSI indicate periods of improving conditions for live fuels and decreasing values indicate periods of detrimental weather conditions. GSI is calculated as a function of the three indicators of important weather factors that regulate plant functions. These indicators are combined into a single indicator that integrates the limiting effects of temperature, water and light deficiencies. The importance of each of the three indicators is explained below and a summary of the Growing Season is given at the conclusion.

Minimum Temperature

Many of the biochemical processes of plants are sensitive to low temperatures. Although ambient air temperatures certainly influence growth, constraints on phenology appear to be more closely related to restrictions on water uptake by roots when soil temperatures are sub optimal and many field studies show variable ecosystem responses over a range of minimum temperatures.

Vapor Pressure Deficit (VPD)

Water stress causes partial to complete stomatal closure, reduces leaf development rate, induces the shedding of leaves, and slows or halts cell division. Although models are available to calculate a soil water balance, they require knowledge of rooting depth, soil texture, latent heat losses, and precipitation. As a surrogate, we selected an index of the evaporative demand, the vapor pressure deficit (VPD) of the atmosphere.

Photoperiod or Daylength

Photoperiod provides a plant with a reliable annual climatic cue because it does not vary from year to year at a given location. We assume that photoperiod provides the outer envelope within which other climatic controls may dictate foliar development. Studies have shown that photoperiod is important to both leaf flush and leaf senescence throughout the world.

Upper and lower limits of the indicator functions used to calculate the Growing Season

Input Variable Unconstrained (1) Completely Limiting (0)
Minimum Temperature 5ºC /41º F -2ºC /28º F
Vapor Pressure Deficit (Pascals) 900 Pascals 4100 Pascals
Photoperiod (Daylength) 11 hours 10 hours

Learn more about the Growing Season Index (GSI)

 

NWCG Latest Announcements

NWCG Training Catalog now on Wildland Fire Learning Portal

Date: April 25, 2023
Contact: NWCG Training  

The National Wildfire Coordinating Group (NWCG) has migrated the training catalog from the NWCG website to the Wildland Fire Learning Portal (WFLP) as part of our ongoing efforts to streamline processes and improve efficiency. To facilitate this transition, the training catalog remains available on www.nwcg.gov through April 2024.

Starting May 2024, the training catalog will no longer be accessible on www.nwcg.gov. However, you can still access the complete training catalog by logging in as a guest to the WFLP.

References:

Wildland Fire Learning Portal

 

NWCG Website Migration

Date: April 01, 2024
Contact: NWCG Webmaster

The National Wildfire Coordinating Group is thrilled to announce a significant upgrade to https://www.nwcg.gov, involving a comprehensive redesign of over 7,000 web pages. This enhancement is focused on improving user experience. The migration to the new NWCG website will commence on April 2, 2024, starting at noon EST and is expected to take a few hours. 

During the migration period, as the www.nwcg.gov domain-name-location updates across the Internet, you might encounter either the current or the new site depending on your location. We request your patience during this transition. If you are not redirected to the new site by April 3, 2024, we recommend clearing your browser’s cache and refreshing the page.

Please note that while navigating the revamped website, there may be instances of broken links or errors. Our dedicated web migration team has made significant efforts to minimize such issues prior to launch and will promptly address any that arise via use of analytic reports. We value your patience and understanding as we work towards enhancing your overall website experience.

WFSTAR 2023 Year in Review and 2024 Core Component Module Packages Available

Date: March 6, 2024
Contact: Joe Schindel 

The 2023 Fire Year in Review module and 2024 Core Component Module Packages for RT-130, Wildland Fire Safety Training Annual Refresher (WFSTAR) are now available on the NWCG website. The 2024 Core Component Module Package provides all content needed to deliver RT-130.

 

References:

WFSTAR 2023 Fire Year in Review module

WFSTAR 2024 Core Component Module Packages

2024 NWCG Executive Board Annual Letter

Date: March 6, 2024
Contact: NWCG

The NWCG Executive Board is privileged to share with you the 2024 NWCG Executive Board Annual Letter. As we look into the future and navigate an incredibly complex and dynamic environment, we must remain focused on our mission while actively engaging in national conversations regarding numerous wildland fire initiatives. In 2024, we prioritize building upon our successes and committing to continuous improvement. Key priorities and considerations for this year include: 

  • Determining Core Workload
  • Ensuring Incident Performance and Training Modernization (IPTM) Success
  • Improving Efficiencies
  • Firefighter Health and Wellness
  • Engagement in National Conversations

Together we will continue to make significant strides in the challenging and vital work that lies ahead. 

 

References:

2024 NWCG Executive Board Annual Letter