WEBVTT 1 00:00:00.691 --> 00:00:03.274 (lively music) 2 00:00:10.325 --> 00:00:15.194 line:15% Change and life is something we can all count on. 3 00:00:15.194 --> 00:00:19.788 line:15% As a plant ecologist, believe it or not, I study change. 4 00:00:19.788 --> 00:00:21.350 In particular, I study the way 5 00:00:21.350 --> 00:00:25.426 that we as a species change our environment. 6 00:00:25.426 --> 00:00:27.376 As humans move round the planet, 7 00:00:27.376 --> 00:00:30.477 we introduce species to new ecosystems. 8 00:00:30.477 --> 00:00:31.847 This is a global phenomenon 9 00:00:31.847 --> 00:00:34.077 that also occurs here in Mississippi. 10 00:00:34.077 --> 00:00:38.247 As you can see in the bar graph at the top left of the slide 11 00:00:38.247 --> 00:00:41.821 as of 2016, there are 15 times as many introduced species 12 00:00:41.821 --> 00:00:45.946 in the state as there were at the turn of the 20th century. 13 00:00:45.946 --> 00:00:49.157 Now about a decade ago, my advisor, Dr. Gary Ervin, 14 00:00:49.157 --> 00:00:53.086 sampled 472 sites across the state of Mississippi, 15 00:00:53.086 --> 00:00:56.084 using funding from the USGS and USDA to compile 16 00:00:56.084 --> 00:00:59.370 the invasive plant atlas of the mid-South. 17 00:00:59.370 --> 00:01:01.764 This database contains information about the ways 18 00:01:01.764 --> 00:01:04.191 that land use and introduced species interact 19 00:01:04.191 --> 00:01:06.467 with natural plant communities. 20 00:01:06.467 --> 00:01:09.479 I used this database to study those relationships, 21 00:01:09.479 --> 00:01:12.768 but I'd like to take the work a step further. 22 00:01:12.768 --> 00:01:15.770 See, plant communities change naturally through time. 23 00:01:15.770 --> 00:01:18.939 It's a process ecologists call succession. 24 00:01:18.939 --> 00:01:23.153 A fire or a storm kills a stand of trees, opens up space 25 00:01:23.153 --> 00:01:27.297 in the canopy and allows sunlight to hit the forest floor. 26 00:01:27.297 --> 00:01:28.996 Plant species that were unable to survive 27 00:01:28.996 --> 00:01:32.754 in the shade of the tall trees, are now able to thrive. 28 00:01:32.754 --> 00:01:34.749 But in time they're overtaken by other species 29 00:01:34.749 --> 00:01:37.863 that are themselves overtaken by the very same tall trees 30 00:01:37.863 --> 00:01:40.103 that fell in the first place. 31 00:01:40.103 --> 00:01:42.465 It's a cyclical process. 32 00:01:42.465 --> 00:01:45.549 I liken this process to that of a dance. 33 00:01:45.549 --> 00:01:48.262 A dance takes a lot of practice to coordinate, 34 00:01:48.262 --> 00:01:50.700 and likewise these species evolved over a long period 35 00:01:50.700 --> 00:01:55.285 of time together to form complex successional relationships. 36 00:01:55.285 --> 00:01:59.221 Introduced species did not evolve in the same context, 37 00:01:59.221 --> 00:02:00.235 and therefore their impact 38 00:02:00.235 --> 00:02:03.652 on natural succession is often not known. 39 00:02:05.467 --> 00:02:09.892 Some of them may join the natural dance of succession. 40 00:02:09.892 --> 00:02:12.969 Others might out compete or duel native species 41 00:02:12.969 --> 00:02:17.136 so thoroughly as to halt or change succession altogether. 42 00:02:18.944 --> 00:02:21.439 This database is a snapshot of what plant communities 43 00:02:21.439 --> 00:02:25.381 looked like 10 years ago, and as such is extremely valuable. 44 00:02:25.381 --> 00:02:28.441 But with your help, it can be made even more valuable 45 00:02:28.441 --> 00:02:31.488 by allowing me to revisit a targeted group of sites, 46 00:02:31.488 --> 00:02:33.798 sample the vegetation communities, 47 00:02:33.798 --> 00:02:35.393 and see how introduced species 48 00:02:35.393 --> 00:02:37.278 are affecting natural succession, 49 00:02:37.278 --> 00:02:39.517 and allow me to answer the question, 50 00:02:39.517 --> 00:02:42.017 do they duel or do they dance?