Abstract
Summary Terrestrial laser scanning (TLS) captures the three‐dimensional structure of habitats. Compared to traditional methods of forest mensuration, it allows quantification of structure at increased resolution, and the derivation of novel metrics with which to inform ecological studies and habitat management. Lowland woodlands in the UK have altered in structure over the last century due to increased abundance of deer and a decline in management. We compared whole‐canopy profiles between woodlands with high (>10 deer km−2) and low deer density (c. 1 deer km−2), and in stands with and without records of management interventions in the last 20 years, providing a test case for the application of TLS in habitat assessment for conservation and management. Forty closed‐canopy lowland woodlands (height range 16·5–29·4 m) were surveyed using TLS in two regions of the UK, divided into areas of high‐ and low‐deer abundance, and between plots which had been recently managed or were unmanaged. Three‐dimensional reconstructions of the woodlands were created to document the density of foliage and stem material across the entire vertical span of the canopy. There was a 68% lower density of understorey foliage (0·5–2 m above‐ground) in high‐deer woodlands, consistent in both regions. Despite this, total amounts of foliage detected across the full canopy did not differ between deer density levels. High‐deer sites were 5 m taller overall and differed in the distribution of foliage across their vertical profile. Managed woodlands, in contrast, exhibited relatively minor differences from controls, including a lower quantity of stem material at heights from 2 to 5 m, but no difference in foliage density. All main effects were replicated equally in both regions despite notable differences in stand structures between them. Synthesis and applications. Terrestrial laser scanning allows ecologists to move beyond two‐dimensional measures of vegetation structure and quantify patterns across complex, heterogeneous, three‐dimensional habitats. Our findings suggest that reduction of deer populations is likely to have a strong impact on woodland structures and aid in restoring the complex understorey habitats required by many birds, whereas management interventions as currently practiced have limited and inconsistent effects.
Highlights
Deer densities in north-temperate forests are at extraordinarily high levels (Côté et al, 2004; Takatsuki, 2009; McShea, 2012)
Our findings suggest that reduction of deer populations is likely to have a strong impact on woodland structures and aid in restoring the complex understorey habitats required by many birds, whereas management interventions as currently practiced have limited and inconsistent effects
Through terrestrial laser scanning we have revealed a marked difference in the foliage profile of high-deer forests which extends beyond the understorey
Summary
Deer densities in north-temperate forests are at extraordinarily high levels (Côté et al, 2004; Takatsuki, 2009; McShea, 2012). This is due to a combination of factors including the absence of large predators, a decline in hunting pressure, concentration of populations in habitat fragments and the widespread invasion of non-native, smaller deer species such as Chinese muntjac Muntiacus reevesi (Côté et al, 2004; Dolman & Wäber, 2008). The increased density of deer has direct impacts on the structure of forests, most markedly through the creation of browse lines where edible foliage has been removed from the understorey, and the imposition of severe recruitment limitation on trees, whose seedlings are damaged and unable to establish (Côté et al, 2004; Gill & Morgan, 2010). The removal of gap-colonising seedlings increases understorey light levels, favouring the growth of herbaceous plants that subsequently impede tree regeneration (Royo & Carson, 2006)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
