Donaldson Jason E, Anderson T Michael, Munuo Norbert, Holdo Ricardo M
Odum School of Ecology, University of Georgia, Athens, Georgia, USA.
Nicholas School of the Environment, Duke University, Durham, North Carolina, USA.
Ecology. 2025 Jan;106(1):e4473. doi: 10.1002/ecy.4473. Epub 2024 Nov 28.
Smaller grazers consistently show greater preference for recently burned patches than larger species. Energy optimization theory posits that this pattern is driven by small- versus large-bodied herbivores seeking to maximize energy intake by choosing high-quality recently burned grasses, or high-quantity unburned grasses, respectively. We propose that if burn preference is driven by an energy-maximization mechanism, then preference should change over time as grass regrows and progresses across the optimal feeding heights of herbivores of increasing body size. To test this, we used a camera trap array in the Serengeti National Park to quantify changes in the relative preference for burned patches of seven ruminant herbivore species. We compared observed patterns to simulation results from a grass production-herbivore patch selection model. Burn preference and herbivore body size scaled negatively for 6 months after fire, but this relationship disappeared after 7 months when smaller species stopped selecting burns, and larger herbivores selected burns after 10 months, in a reversal of classic grazer succession. Simulations recreated the former but not the latter relationship, suggesting that an energy-maximization mechanism can drive allometric scaling of burn preference immediately after fire, but over longer periods, grazer-driven feedbacks are required to explain large herbivore burn preferences.
体型较小的食草动物一直比体型较大的物种对近期被火烧过的区域表现出更强的偏好。能量优化理论认为,这种模式是由小型和大型食草动物分别通过选择高质量的近期被火烧过的草或数量更多的未被火烧过的草来寻求能量摄入最大化所驱动的。我们提出,如果火烧偏好是由能量最大化机制驱动的,那么随着草的生长并跨越体型不断增大的食草动物的最佳采食高度,偏好应该会随时间发生变化。为了验证这一点,我们在塞伦盖蒂国家公园使用了一个相机陷阱阵列,以量化七种反刍食草动物物种对火烧区域的相对偏好变化。我们将观察到的模式与一个草产量 - 食草动物斑块选择模型的模拟结果进行了比较。火烧后6个月,火烧偏好与食草动物体型呈负相关,但7个月后这种关系消失了,此时较小的物种不再选择火烧区域,而较大的食草动物在10个月后选择火烧区域,这与经典的食草动物演替情况相反。模拟重现了前者但没有重现后者的关系,这表明能量最大化机制可以在火烧后立即驱动火烧偏好的异速生长缩放,但在更长的时期内,需要食草动物驱动的反馈来解释大型食草动物的火烧偏好。