Dataset Information

Improving distribution models of riparian vegetation with mobile laser scanning and hydraulic modelling.

ABSTRACT: This study aimed at illustrating how direct measurements, mobile laser scanning and hydraulic modelling can be combined to quantify environmental drivers, improve vegetation models and increase our understanding of vegetation patterns in a sub-arctic river valley. Our results indicate that the resultant vegetation models successfully predict riparian vegetation patterns (Rho = 0.8 for total species richness, AUC = 0.97 for distribution) and highlight differences between eight functional species groups (Rho 0.46-0.84; AUC 0.79-0.93; functional group-specific effects). In our study setting, replacing the laser scanning-based and hydraulic modelling-based variables with a proxy variable elevation did not significantly weaken the models. However, using directly measured and modelled variables allows relating species patterns to e.g. stream power or the length of the flood-free period. Substituting these biologically relevant variables with proxies mask important processes and may reduce the transferability of the results into other sites. At the local scale, the amount of litter is a highly important driver of total species richness, distribution and abundance patterns (relative influences 49, 72 and 83%, respectively) and across all functional groups (13-57%; excluding lichen species richness) in the sub-arctic river valley. Moreover, soil organic matter and soil water content shape vegetation patterns (on average 16 and 7%, respectively). Fluvial disturbance is a key limiting factor only for lichen, bryophyte and dwarf shrub species in this environment (on average 37, 6 and 10%, respectively). Fluvial disturbance intensity is the most important component of disturbance for most functional groups while the length of the disturbance-free period is more relevant for lichens. We conclude that striving for as accurate quantifications of environmental drivers as possible may reveal important processes and functional group differences and help anticipate future changes in vegetation. Mobile laser scanning, high-resolution digital elevation models and hydraulic modelling offer useful methodology for improving correlative vegetation models.

SUBMITTER: Nylen T

PROVIDER: S-EPMC6894786 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:The primary objective of this study was to test the relevance of hydrological classification and class differences to the characteristics of woody riparian vegetation in a subtropical landscape in Queensland, Australia. We followed classification procedures of the environmental flow framework ELOHA - Ecological Limits of Hydrologic Alteration. Riparian surveys at 44 sites distributed across five flow classes recorded 191 woody riparian species and 15, 500 individuals. There were differences among flow classes for riparian species richness, total abundance, and abundance of regenerating native trees and shrubs. There were also significant class differences in the occurrence of three common tree species, and 21 indicator species (mostly native taxa) further distinguished the vegetation characteristics of each flow class. We investigated the influence of key drivers of riparian vegetation structure (climate, depth to water table, stream-specific power, substrate type, degree of hydrologic alteration, and land use) on riparian vegetation. Patterns were explained largely by climate, particularly annual rainfall and temperature. Strong covarying drivers (hydrology and climate) prevented us from isolating the independent influences of these drivers on riparian assemblage structure. The prevalence of species considered typically rheophytic in some flow classes implies a more substantial role for flow in these classes but needs further testing. No relationships were found between land use and riparian vegetation composition and structure. This study demonstrates the relevance of flow classification to the structure of riparian vegetation in a subtropical landscape, and the influence of covarying drivers on riparian patterns. Management of environmental flows to influence riparian vegetation assemblages would likely have most potential in sites dominated by rheophytic species where hydrological influences override other controls. In contrast, where vegetation assemblages are dominated by a diverse array of typical rainforest species, and other factors including broad-scale climatic gradients and topographic variables have greater influence than hydrology, riparian vegetation is likely to be less responsive to environmental flow management.

Project description:This data article is on riparian vegetation species richness in four different streams located in the Sultan Mahmud Hydroelectric dam, also known as Kenyir dam and commonly referred to as Tasik Kenyir, Terengganu. The dataset consists of three reservoir-island streams and the other is a small stream located on the mainland. A total of 41 families and 90 species of riparian plants were reported for the first time after 34 years of the establishment of the Sultan Mahmud Hydroelectric dam. Trees contributing 60% of the species recorded in this study and the others were non-tree species, including climbers, ferns, epiphyte, herbs, shrub, strangling trees and palms. Among the recorded riparian plant species, two are introduced which are Clidemia hirta and Mimosa pigra. The highest diversity of riparian plant found in the stream of Sungai Kiang, followed by Sungai Ikan and Sungai Saok with 46, 29 and 17 species respectively for the reservoir-island streams. The mainland stream, Sungai Siput recorded 37 species. These riparian plants provide important ecosystem services, among others soil stabilization, habitat and food for aquatic fauna and water filtration. In terms of plant utilization potential and values, 47 species are identified having medicinal value, 10 species with ornamental value and another 36 species are timber trees. Our study demonstrates that the riparian plants are closely linked to stream size with variability associated with types of stream systems. The data collected also demonstrates that the riparian plant community is at the seral stages of riparian forest. This is indicated by the increase in plant species richness as the vegetation gradually changes from riparian towards mature forest composition. To secure ecological functions of Tasik Kenyir riparian plant assemblages, particularly in stabilizing the lake's margin and riverbank, it is recommended that monitoring and legal protection may need to be imposed by local authority.

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Improving distribution models of riparian vegetation with mobile laser scanning and hydraulic modelling.

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