Traits influence detection of exotic plant species in tropical forests

Abstract

Detecting exotic plant species is essential for invasive species management. By accounting for factors likely to affect species’ detection rates (e.g. survey conditions, observer experience), detectability models can help choose search methods and allocate search effort. Integrating information on species’ traits can refine detectability models, and might be particularly valuable if these traits can help improve estimates of detectability where data on particular species are rare. Analysing data collected during line transect distance sampling surveys in Indonesia, we used a multi-species hierarchical distance sampling model to evaluate how plant height, leaf size, leaf shape, and survey location influenced plant species detectability in secondary tropical rainforests. Detectability of the exotic plant species increased with plant height and leaf size. Detectability varied among the different survey locations. We failed to detect a clear effect of leaf shape on detectability. This study indicates that information on traits might improve predictions about exotic species detection, which can then be used to optimise the allocation of search effort for efficient species management. The innovation of the study lies in the multi-species distance sampling model, where the distance-detection function depends on leaf traits and height. The method can be applied elsewhere, including for different traits that may be relevant in other contexts. Trait-based multispecies distance sampling can be a practical approach for sampling exotic shrubs, herbs, or grasses species in the understorey of tropical forests.

Application of distance sampling for assessing abundance and habitat relationships of a rare Sonoran Desert cactus

“…Understanding factors that influence P is useful for guiding survey design because optimal survey techniques have a high and consistent probability of detecting the target species and low sampling error (Thompson et al 1998;Williams et al 2002). Although few studies assess factors that influence detectability of plants, traits such as color, flowering time, leaf size, height, and observer ability can influence the detection process (Chen et al 2013;Garrard et al 2013;Junaedi et al 2018). We found that detectability during DS was explained by variation in soil substrate size, with lower detectability on rockier soils.…”

“…Distance sampling has been used successfully to assess abundance and detection probability (P) in animal systems, often at much larger spatial scales than that considered here (Thomas et al 2002(Thomas et al , 2010Buckland et al 2015;Roberts et al 2016). To our knowledge, however, this study represents just its eighth application in a plant system (Marsden and Pilgrim 2003;Buckland et al 2007;Crase et al 2010;Jensen and Meilby 2012;Kissa and Sheil 2012;Schorr 2013;Phama et al 2014;Junaedi et al 2018), and is the first to compare estimates from DS with what we assumed were parametric values of abundances from intensive censuses.…”

“…For uncommon and cryptic plants, however, accurate estimates of population parameters can be costly to obtain, and thus developing new more efficient methods is useful. Although many species of plants are readily detectable in the field, probability of detecting individuals that are present and available for sampling is rarely perfect and can vary with species' traits, and environmental and survey conditions (Chen et al, 2009(Chen et al, , 2013Garrard et al 2013;Junaedi et al 2018). Understanding factors that influence the detection process can help guide survey and sampling designs, and explicitly modeling these factors can improve the accuracy of inferences (Buckland et al 2001;Chen et al 2009;Dénes et al 2015).…”

SEBARAN POPULASI Cobaea scandens CAV. SEBAGAI TUMBUHAN INVASIF DI KEBUN RAYA CIBODAS DAN SEKITARNYA

“…Jenis tersebut juga telah dianggap sebagai salah satu tumbuhan invasif di kawasan hutan di Indonesia, yaitu TNGGP dan kawasan hutan di Sumatera Utara (Tjitrosoedirdjo et al, 2016). Meskipun demikian, dalam sejumlah studi terkini mengenai jenis tumbuhan invasif di kawasan KRC dan sekitar kawasan TNGGP (Mutaqien et al, 2011;Zuhri & Mutaqien, 2013;Junaedi, 2014;Junaedi et al, 2018), jenis tersebut luput dari perhatian. Oleh karena itu, penelitian ini bertujuan memberikan informasi persebaran populasi dan karakteristik habitat dari C. Scandens di kawasan KRC dan TNGGP.…”

“…Kondisi tersebut dapat memberikan dampak negatif terhadap ekosistem yang berada di sekitarnya, seperti yang ditemukan pada tumbuhan pemanjat lainnya (Hu & Li, 2014). Selain itu, rapatnya vegetasi C. quadringularis dan keberadaan jenis invasif lainnya (Mutaqien et al, 2011;Wahyuni & Tjitrosoedirdjo, 2013;Junaedi, 2014;Damayanto & Muhaimin, 2017;Tjitrosoedirdjo et al, 2016;Junaedi et al, 2018), menjadi hambatan dalam pengendalian C. scandens lebih lanjut.…”