Kevin Faccenda Elizabeth Aquino Peterson Kelsey C. Brock Lucas B. Fortini Curtis Daehler 2026 <h3 id="ddi70190-sec-0001-title" class="article-section__sub-title section1">Aim</h3><p>Grasses comprise three main photosynthetic pathway variants (C₃-BOP, C₃-PACMAD and C₄-PACMAD hereafter referred to as C₄). We sought to confirm climate niche differences among these photosynthetic pathway variants and assessed whether predicted non-native grass range shift patterns with climate change differ among photosynthetic pathway variants.</p><h3 id="ddi70190-sec-0002-title" class="article-section__sub-title section1">Location</h3><p>Hawaiian Islands.</p><h3 id="ddi70190-sec-0003-title" class="article-section__sub-title section1">Methods</h3><p>We used a species distribution modelling (SDM) approach that uses global occurrence records to inform local SDM based on local (Hawaiian Islands) occurrences. We compared climate niches and projected climate-driven range shifts, assuming moderate climate change (RCP 4.5, end of century), among 22 non-native grasses representing C₃-BOP, C₃-PACMAD and C₄<span>&nbsp;</span>photosynthetic pathway variants.</p><h3 id="ddi70190-sec-0004-title" class="article-section__sub-title section1">Results</h3><p>C₄<span>&nbsp;</span>grasses exhibited the warmest temperature niches on average, but did not differ substantially in rainfall niche versus C₃-BOP grasses. C₃-PACMAD species averaged high suitability across a broad range of temperatures and rainfall conditions, except extreme aridity. In response to projected climate change, C₄<span>&nbsp;</span>grasses had projected range increases. C₃-BOP grasses typically responded with net range decreases, while C₃-PACMAD grasses had variable range responses. However, patterns were contingent on elevation: for instance, the projected expansion of C₄<span>&nbsp;</span>grasses was generally limited to elevations below 2000 m, with the largest increases in areas up to ~750 m. Areas of greatest reduction for C₃-BOP and C₃-PACMAD were projected at 750–1900 m and 100–1100 m elevation, respectively. Above 2000 m, range increases were projected for both C₃<span>&nbsp;</span>grass variants.</p><h3 id="ddi70190-sec-0005-title" class="article-section__sub-title section1">Main Conclusions</h3><p>Our projections suggest that non-native C₄<span>&nbsp;</span>grasses pose the greatest risk for increasing spread and impacts under RCP 4.5, while certain C₃-PACMAD grasses may endanger valuable high-elevation habitats. Photosynthetic pathway may be a useful component of weed risk assessment to evaluate how species may respond to climate change as similar range response patterns may be expected for other non-native grasses in other tropical and subtropical regions.</p> application/pdf 10.1111/ddi.70190 en Wiley Predicted range shifts of non‐native grasses in response to climate change are influenced by photosynthetic pathway: A case study in the Hawaiian Islands article