{"id":4668,"date":"2021-12-13T09:53:10","date_gmt":"2021-12-13T07:53:10","guid":{"rendered":"https:\/\/blogs.sun.ac.za\/cib\/?p=4668"},"modified":"2021-12-13T09:53:10","modified_gmt":"2021-12-13T07:53:10","slug":"mountain-roads-as-conduits-for-ongoing-exotic-species-expansion","status":"publish","type":"post","link":"https:\/\/blogs.sun.ac.za\/cib\/mountain-roads-as-conduits-for-ongoing-exotic-species-expansion\/","title":{"rendered":"Mountain roads as conduits for ongoing exotic species expansion"},"content":{"rendered":"

A recent study by Jesse Kalwij, former C\u2219I\u2219B MSc student, Sophia Turner, and C\u2219I\u2219B Core Team member, Karen Esler, shows that human activities are the primary cause of exotic species introduction and expansion up the Sani Pass, as well as from the disturbed road verges into the adjacent natural area. Despite a surge of research on exotic species in alpine habitats, a lack of reliable baseline data has inhibited long-term understanding about exotic species dynamics in mountain ecosystems across the world. A longitudinal study of species invasion in the Drakensberg region of South Africa provides an important exception.<\/p>\n

By resurveying exotic species richness and composition in transects ten years after an initial survey, conducted in 2007, the authors were able to uncover \u00a0in exotic species richness and composition.<\/p>\n

They found that over time, not only has exotic species richness remained spatially clustered around four points of introduction \u2013 the two passport control areas, a picnic site, and an old trading post \u2013 but has also increased along the entire elevational gradient. This shows that human-mediated dispersal is the primary cause of exotic species increase along the pass.<\/p>\n

Furthermore, the exotic species composition between road verge and natural transects has begun homogenizing over the past decade. Most of the exotic species occurring in this area are hardy species that thrive in disturbed habitats. So, the combination of regular colonization pressure with suitable habitat has allowed for their spread beyond the confines of the road verge, compromising the adjacent natural vegetation.<\/p>\n

These results show that mountain roads are far better conduits for exotic species expansion than previously assumed, which is likely due to the continual road maintenance. Since private vehicles are generally cleaned more regularly than construction vehicles, road maintenance rather than regular traffic introduces more propagules to the area.<\/p>\n

\u201cEach new invasion starts with a single propagule<\/em>,\u201d said Dr Jesse Kalwij. \u201cFor example,<\/em> we observed a<\/em>n individual<\/em> Parthenium hysterophorus at<\/em> an active construction site<\/em> \u2014 the<\/em> first <\/em>recorded <\/em>observation of this invasive<\/em> alien species in the study area<\/em>. <\/em>Since these construction<\/em> vehicles originated from an area where <\/em>P. hysterophorus is particularly<\/em> abundant (Richards Bay, South Africa; approximately 400 km from<\/em> the study area), it is a plausible assumption that a construction vehicle<\/em> was the dispersal vector in this case<\/em>.\u201d<\/p><\/blockquote>\n

The Sani Pass is part of one of South Africa\u2019s eight World Heritage Sites, therefore preserving its ecosystem integrity of this area is of high value. The fact that the spread of exotic species is human-mediated means that it can be managed.<\/p>\n

\u201cThe temporal nature of this study allowed us to identify which species were successful colonizers over a decade<\/em>,\u201d said Sophia Turner, \u201cin doing so, we were able to identify invasion pathways specific to those successful species, thereby aiding targeted management<\/em>.\u201d<\/p><\/blockquote>\n

Read the full paper<\/strong><\/h4>\n

Turner, S.C, Esler, K.J.E. and Kalwij, J.M. (2021) Road verges facilitate exotic species expansion into undisturbed natural montane grasslands. Applied Vegetation Science<\/em>. https:\/\/doi.org\/10.1111\/avsc.12615<\/a><\/p>\n

For more information, contact Sophia Turner at sturne62@vols.utk.edu<\/a><\/p>\n

\"\"
The study site \u2013 the Sani Pass Road, surveyed from 1500 m \u2013 2874 m above sea level in 2007 and 2017. (Photo credit: Sophia Turner)<\/figcaption><\/figure>\n","protected":false},"excerpt":{"rendered":"

A study by Jesse Kalwij, former C\u2219I\u2219B MSc student, Sophia Turner, and C\u2219I\u2219B Core Team member, Karen Esler, shows that human activities are the primary cause of exotic species introduction and expansion up the Sani Pass, as well as from the disturbed road verges into the adjacent natural area.<\/p>\n","protected":false},"author":11009,"featured_media":4672,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"ocean_post_layout":"","ocean_both_sidebars_style":"","ocean_both_sidebars_content_width":0,"ocean_both_sidebars_sidebars_width":0,"ocean_sidebar":"","ocean_second_sidebar":"","ocean_disable_margins":"enable","ocean_add_body_class":"","ocean_shortcode_before_top_bar":"","ocean_shortcode_after_top_bar":"","ocean_shortcode_before_header":"","ocean_shortcode_after_header":"","ocean_has_shortcode":"","ocean_shortcode_after_title":"","ocean_shortcode_before_footer_widgets":"","ocean_shortcode_after_footer_widgets":"","ocean_shortcode_before_footer_bottom":"","ocean_shortcode_after_footer_bottom":"","ocean_display_top_bar":"default","ocean_display_header":"default","ocean_header_style":"","ocean_center_header_left_menu":"","ocean_custom_header_template":"","ocean_custom_logo":0,"ocean_custom_retina_logo":0,"ocean_custom_logo_max_width":0,"ocean_custom_logo_tablet_max_width":0,"ocean_custom_logo_mobile_max_width":0,"ocean_custom_logo_max_height":0,"ocean_custom_logo_tablet_max_height":0,"ocean_custom_logo_mobile_max_height":0,"ocean_header_custom_menu":"","ocean_menu_typo_font_family":"","ocean_menu_typo_font_subset":"","ocean_menu_typo_font_size":0,"ocean_menu_typo_font_size_tablet":0,"ocean_menu_typo_font_size_mobile":0,"ocean_menu_typo_font_size_unit":"px","ocean_menu_typo_font_weight":"","ocean_menu_typo_font_weight_tablet":"","ocean_menu_typo_font_weight_mobile":"","ocean_menu_typo_transform":"","ocean_menu_typo_transform_tablet":"","ocean_menu_typo_transform_mobile":"","ocean_menu_typo_line_height":0,"ocean_menu_typo_line_height_tablet":0,"ocean_menu_typo_line_height_mobile":0,"ocean_menu_typo_line_height_unit":"","ocean_menu_typo_spacing":0,"ocean_menu_typo_spacing_tablet":0,"ocean_menu_typo_spacing_mobile":0,"ocean_menu_typo_spacing_unit":"","ocean_menu_link_color":"","ocean_menu_link_color_hover":"","ocean_menu_link_color_active":"","ocean_menu_link_background":"","ocean_menu_link_hover_background":"","ocean_menu_link_active_background":"","ocean_menu_social_links_bg":"","ocean_menu_social_hover_links_bg":"","ocean_menu_social_links_color":"","ocean_menu_social_hover_links_color":"","ocean_disable_title":"default","ocean_disable_heading":"default","ocean_post_title":"","ocean_post_subheading":"","ocean_post_title_style":"","ocean_post_title_background_color":"","ocean_post_title_background":0,"ocean_post_title_bg_image_position":"","ocean_post_title_bg_image_attachment":"","ocean_post_title_bg_image_repeat":"","ocean_post_title_bg_image_size":"","ocean_post_title_height":0,"ocean_post_title_bg_overlay":0.5,"ocean_post_title_bg_overlay_color":"","ocean_disable_breadcrumbs":"default","ocean_breadcrumbs_color":"","ocean_breadcrumbs_separator_color":"","ocean_breadcrumbs_links_color":"","ocean_breadcrumbs_links_hover_color":"","ocean_display_footer_widgets":"default","ocean_display_footer_bottom":"default","ocean_custom_footer_template":"","ocean_post_oembed":"","ocean_post_self_hosted_media":"","ocean_post_video_embed":"","ocean_link_format":"","ocean_link_format_target":"self","ocean_quote_format":"","ocean_quote_format_link":"post","ocean_gallery_link_images":"off","ocean_gallery_id":[],"footnotes":""},"categories":[76019,3256],"tags":[71719,76376,76377,76378,71812,76379,76380],"class_list":["post-4668","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-76019","category-news","tag-alien-species","tag-biodiversity-monitoring","tag-high-elevation-environments","tag-montane-grasslands","tag-non-native-species","tag-road-construction","tag-road-verge","entry","has-media"],"acf":[],"_links":{"self":[{"href":"https:\/\/blogs.sun.ac.za\/cib\/wp-json\/wp\/v2\/posts\/4668","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blogs.sun.ac.za\/cib\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.sun.ac.za\/cib\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.sun.ac.za\/cib\/wp-json\/wp\/v2\/users\/11009"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.sun.ac.za\/cib\/wp-json\/wp\/v2\/comments?post=4668"}],"version-history":[{"count":2,"href":"https:\/\/blogs.sun.ac.za\/cib\/wp-json\/wp\/v2\/posts\/4668\/revisions"}],"predecessor-version":[{"id":4673,"href":"https:\/\/blogs.sun.ac.za\/cib\/wp-json\/wp\/v2\/posts\/4668\/revisions\/4673"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blogs.sun.ac.za\/cib\/wp-json\/wp\/v2\/media\/4672"}],"wp:attachment":[{"href":"https:\/\/blogs.sun.ac.za\/cib\/wp-json\/wp\/v2\/media?parent=4668"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.sun.ac.za\/cib\/wp-json\/wp\/v2\/categories?post=4668"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.sun.ac.za\/cib\/wp-json\/wp\/v2\/tags?post=4668"}],"curies":[{"name":"wp","href":"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