Study Finds Wildfire Isn't Primary Factor in Invasive Annual Grass Expansion in Great Basin
Contact: Maribel Alonso
October 16, 2023
Scientists examined the assumption that wildfires are the primary factor driving the expansion of invasive annual grasses that are taking over shrubland and grassland in the U.S. Great Basin and found that annual grasses are highly competitive even in the absence of significant disturbances like fire.
In fact, according to the study conducted by scientists at the U.S. Department of Agriculture (USDA) Agricultural Research Service (ARS) and Working Lands for Wildlife-affiliated researchers at the University of Montana (UMT), almost 80% of the shrublands and grasslands in the U.S. Great Basin that have transitioned to annual grass dominance have done so without burning in the preceding 10 years.
Native perennial grasses and shrubs have a critical role in the arid and semi-arid regions of the U.S. Great Basin, as they benefit wildlife, provide livestock forage, and sequester carbon. The rapid spread of invasive annual grasses, including cheatgrass (Bromus tectorum), medusahead (Taeniatherum caput-medusae), red brome (B. rubens), ventenata (Ventenata dubia), and others, has fundamentally altered these plant communities.
As annual grasses invade, they fill the spaces between native perennial grasses and shrubs. This creates near-continuous fuels that dry out early in the growing season, enabling the ignition and spread of wildfires and creating a grass-fire cycle, which contributes to the widespread dominance of invasive annual grasses and higher chances of wildfires. Previous studies have revealed that these grasses already dominate a fifth of Great Basin rangelands, causing significant ecological disturbances.
"We found that wildfire is not the predominant driver of invasive annual grass expansion in the Great Basin, but it is still a major issue that can promote annual grass abundance and negatively impact a wide variety of ecosystem services and values ranging from forage for cattle production to sagebrush obligate wildlife habitat," said Chad Boyd, co-author, and research leader at the USDA-ARS Range and Meadow Forage Management Research Unit. "However, annual grass management focused solely on wildfire suppression and post-fire restoration is unlikely to reverse widespread conversion to invasive annual grasses."
The research team used dynamic, remote sensing-derived datasets from 1994 to 2020 to analyze transitions of annual grass dominance in the U.S. Great Basin. The datasets included fire perimeter and burn severity datasets obtained from the Monitoring Trends in Burn Severity program and maps of annual grass-dominated vegetation communities based on the Rangeland Analysis Platform.
The 26 years' worth of data scientists examined in the study shows that wildfire is not the main factor driving the rapid expansion, degradation, and domination of native plant communities by annual grasses in the region. Adopting a preventive approach to manage invasive grasses before a wildfire occurs is necessary to control the grass-fire cycle and slow down transitions to annual grass dominance.
"Firefighters already extinguish 97% of wildfires before they reach 1,000 acres, yet we're still getting flanked by cheatgrass," said Joe Smith, co-author and NRCS-Working Lands for Wildlife affiliate at UMT. "We need to get ahead of future fires by proactively defending intact landscapes against cheatgrass expansion."
Full details of the study were published in the journal Biological Conservation by Joseph T. Smith (UMT), Brady W. Allred (UMT), Chad S. Boyd (USDA-ARS), Kirk W. Davies (USDA-ARS), Andrew R. Kleinhesselink (UMT), Scott L. Morford (UMT), David E. Naugle (UMT).
The team calls for collaborative efforts to be redirected towards a more preventive approach [rather than reactive], using management strategies to control the spread of invasive species and slow the degradation of these ecosystems.
The Agricultural Research Service is the U.S. Department of Agriculture's chief scientific in-house research agency. Daily, ARS focuses on solutions to agricultural problems affecting America. Each dollar invested in U.S. agricultural research results in $20 of economic impact.
"Kuchunguza ""Moto wa mwituni sio sababu ya msingi katika upanuzi wa nyasi ya kila mwaka katika Bonde Kubwa la Amerika"" - Maribel Alonso, Oktoba 16, 2021 - Wataalamu wa utafiti wa utafiti wa utafiti wa utafiti wa utafiti wa utafiti wa utafiti wa utafiti wa utafiti wa utafiti wa utafiti wa utafiti wa utafiti wa utafiti wa utafiti wa utafiti wa utafiti wa utafiti wa utafiti wa utafiti wa utafiti wa utafiti wa utafiti wa utafiti wa utafiti wa utafiti wa utafiti wa utafiti wa utafiti wa utafiti wa utafiti wa utafiti wa utafiti wa utafiti wa utafiti wa utafiti wa utafiti wa utafiti wa utafiti." Kulingana na utafiti uliofanywa na wanasayansi wa Wizara ya Kilimo ya Marekani (USDA) na Shirika la Utafiti wa Kilimo (ARS) na Working Lands for Wildlife (WLW) katika Chuo Kikuu cha Montana, karibu 80% ya misitu na nyasi katika Bonde Kuu la Marekani ambazo zimebadilika kuwa nyasi za kila mwaka zimefanya hivyo bila kuchoma katika miaka 10 iliyopita. Nyasi na vichaka vya kudumu vya asili vina jukumu muhimu katika maeneo ya kavu na nusu kavu ya Bonde Kuu la Marekani, kwani zinafaidi wanyama wa porini, hutoa chakula cha mifugo, na kuhifadhi kaboni. Kuenea kwa haraka kwa nyasi za kila mwaka, ikiwa ni pamoja na cheatgrass (Bromus tectorum), medusa (Taeniatherum caput-medusae), bromine nyekundu (B. rubens), ventenata (Ventenata dubia), na wengine, imebadilisha kabisa jamii hizi za mimea. Wakati nyasi za kila mwaka zinapoingia, zinajaza nafasi zilizo kati ya nyasi na vichaka vya kudumu vya kienyeji. Hii huunda karibu-mfululizo wa mafuta ambayo hukauka mapema katika msimu wa kukua, kuwezesha kuzima na kuenea kwa moto wa misitu na kuunda mzunguko wa moto wa nyasi, ambayo inachangia kutawala kwa wingi wa nyasi za kila mwaka na uwezekano mkubwa wa moto wa misitu. Uchunguzi wa awali umeonyesha kwamba nyasi hizo tayari zinatawala sehemu moja ya tano ya malisho ya Bonde Kuu, zikisababisha matatizo makubwa ya ikolojia. "Tunakubaliana na Chad Boyd, mwandishi mwenza na kiongozi wa utafiti katika kitengo cha utafiti cha USDA cha Range na Meadow Forage Management, ""Moto wa mwituni sio kichocheo cha kuenea kwa nyasi ya kila mwaka katika Bonde Kuu, lakini bado ni suala kubwa ambalo linaweza kukuza wingi wa nyasi ya kila mwaka na kuathiri vibaya huduma mbalimbali za ikolojia na maadili kuanzia malisho kwa uzalishaji wa ng'ombe hadi mazingira ya wanyama wa porini." Hata hivyo, usimamizi wa nyasi za kila mwaka uliokazia tu kuzima moto wa mwituni na kurudisha baada ya moto hauwezi kugeuza mabadiliko ya kuenea kwa nyasi za kila mwaka zenye uvamizi. Timu ya utafiti ilitumia seti za data za nguvu za sensorer za mbali kutoka 1994 hadi 2020 kuchambua mabadiliko ya utawala wa nyasi ya kila mwaka katika Bonde Kuu la Amerika. "Kati ya data zilizopatikana, ""perimeter ya moto na data ya ukali wa kuchoma"" zilitolewa kutoka kwa programu ya Ufuatiliaji wa Mwelekeo wa Ukali wa Kuungua na ramani za jamii za mimea ya nyasi ya kila mwaka kulingana na Jukwaa la Uchambuzi wa Rangeland." "Wanasayansi wa miaka 26 waliochunguza data katika utafiti huo wanaonyesha kwamba moto wa mwituni sio sababu kuu inayoendesha upanuzi wa haraka, uharibifu, na utawala wa jamii za mimea ya asili na nyasi za kila mwaka katika mkoa huo. """ Kuchukua mbinu ya kuzuia kusimamia nyasi za uvamizi kabla ya moto wa misitu kutokea ni muhimu kudhibiti mzunguko wa moto wa nyasi na kupunguza mabadiliko ya kutawala nyasi ya kila mwaka. "Wazima moto tayari kuzima 97% ya moto kabla ya kufikia 1,000 ekari, lakini bado sisi ni kupata flanked na cheatgrass, ""alisema Joe Smith, mwandishi mwenza na NRCS-Kazi ya Ardhi kwa ajili ya Wildlife mshirika katika UMT." "Tunahitaji kuepuka moto wa wakati ujao kwa kutetea kwa bidii mandhari zisizoharibiwa dhidi ya kuenea kwa nyasi za udanganyifu". Utafiti huo ulichapishwa katika jarida la Biological Conservation na Joseph T. Smith (UMT), Brady W. Allred (UMT), Chad S. Boyd (USDA-ARS), Kirk W. Davies (USDA-ARS), Andrew R. Kleinhesselink (UMT), Scott L. Morford (UMT), na David E. Naugle (UMT). Timu hiyo inatoa wito kwa juhudi za ushirikiano kuelekezwa kwa njia ya kuzuia zaidi [mbele ya kukabiliana], kwa kutumia mikakati ya usimamizi kudhibiti kuenea kwa spishi za uvamizi na kupunguza uharibifu wa mifumo hii ya ikolojia. Huduma ya Utafiti wa Kilimo (AIRS) ni idara ya utafiti wa ndani ya Wizara ya Kilimo ya Marekani. Kila siku, ARS inazingatia suluhisho la matatizo ya kilimo yanayoathiri Amerika. Kila dola iliyowekezwa katika utafiti wa kilimo nchini Marekani inamaanisha athari ya kiuchumi ya dola 20.