1 00:00:12,060 --> 00:00:15,140 - Welcome to the forest pests and diseases tract 2 00:00:16,004 --> 00:00:19,053 at the FEMC 2020 conference. 3 00:00:19,890 --> 00:00:23,963 I will introduce Laura Hancock. 4 00:00:25,280 --> 00:00:29,160 She is with the University of Massachusetts Amherst 5 00:00:29,160 --> 00:00:31,120 and will be presenting 6 00:00:31,120 --> 00:00:34,400 about trait variation and long-term population dynamics 7 00:00:34,400 --> 00:00:36,900 of the invasive garlic mustard 8 00:00:36,900 --> 00:00:40,079 across three forest microhabitats. 9 00:00:40,079 --> 00:00:42,940 - So broadly I want to start my presentation 10 00:00:44,000 --> 00:00:46,040 by talking about some of the theoretical concepts 11 00:00:46,040 --> 00:00:48,720 which underpin much of my study 12 00:00:48,720 --> 00:00:49,870 that I'll be presenting today, 13 00:00:49,870 --> 00:00:51,210 and will hopefully help us 14 00:00:51,210 --> 00:00:53,650 to better understand how certain pests 15 00:00:53,650 --> 00:00:56,470 and invasive species impact our forest ecosystems, 16 00:00:56,470 --> 00:00:58,640 thus allowing us to better protect them. 17 00:00:58,640 --> 00:01:01,490 And so understanding connections between habitats, 18 00:01:01,490 --> 00:01:04,740 especially those of differing suitability or quality, 19 00:01:04,740 --> 00:01:07,110 could be critical to predicting other species ability 20 00:01:07,110 --> 00:01:09,940 to adapt to and persist in new areas and habitats, 21 00:01:09,940 --> 00:01:12,190 whether those be species we want to see in habitats 22 00:01:12,190 --> 00:01:13,780 or species we don't want to see in habitats, 23 00:01:13,780 --> 00:01:15,860 such as invasive species. 24 00:01:15,860 --> 00:01:18,940 And so I'm specifically talking about, 25 00:01:18,940 --> 00:01:20,160 and what my study focuses on, 26 00:01:20,160 --> 00:01:22,850 is source-sink dynamics and metapopulation structure, 27 00:01:22,850 --> 00:01:25,410 specifically in relation to invasion mechanisms 28 00:01:25,410 --> 00:01:27,730 and how source-sink dynamics may play a role 29 00:01:27,730 --> 00:01:30,130 in invasion success of certain species. 30 00:01:30,130 --> 00:01:31,550 And so the picture 31 00:01:31,550 --> 00:01:34,520 on the right is sort of a visual depiction 32 00:01:34,520 --> 00:01:37,050 of what source-sink dynamics is 33 00:01:37,050 --> 00:01:40,480 for anyone who's unfamiliar with that theoretical concept. 34 00:01:40,480 --> 00:01:42,580 So those circles, which are labeled sources 35 00:01:42,580 --> 00:01:45,190 and have the little sun icons 36 00:01:45,190 --> 00:01:46,850 to represent high quality habitat, 37 00:01:46,850 --> 00:01:48,520 which has a lot of light availability say 38 00:01:48,520 --> 00:01:50,440 for plants that need a lot of light, 39 00:01:50,440 --> 00:01:52,250 and then there are these green circles 40 00:01:52,250 --> 00:01:53,120 that are labeled sinks, 41 00:01:53,120 --> 00:01:55,980 which have these little trees and shading. 42 00:01:55,980 --> 00:01:58,310 So maybe indicating lower quality habitat 43 00:01:58,310 --> 00:01:59,230 that's really shaded, 44 00:01:59,230 --> 00:02:01,990 not a lot of resource availability in terms of light. 45 00:02:01,990 --> 00:02:03,870 And so those arrows that are connecting the sources 46 00:02:03,870 --> 00:02:07,130 and the sinks represent propagule dispersal 47 00:02:07,130 --> 00:02:08,400 from those areas. 48 00:02:08,400 --> 00:02:09,320 And so as you can see, 49 00:02:09,320 --> 00:02:14,180 the sources are having allowing propagules, 50 00:02:14,180 --> 00:02:16,400 because sources are such high quality habitat, 51 00:02:16,400 --> 00:02:18,120 species produce a lot of propagules. 52 00:02:18,120 --> 00:02:19,980 So say seeds, if we're talking about plants, 53 00:02:19,980 --> 00:02:21,690 which is what I'm going to focus on, 54 00:02:21,690 --> 00:02:24,300 and those seeds or propagules will disperse 55 00:02:24,300 --> 00:02:25,480 out into sinks. 56 00:02:25,480 --> 00:02:27,070 And so those sinks have populations 57 00:02:27,070 --> 00:02:29,200 which aren't necessarily self-sustaining. 58 00:02:29,200 --> 00:02:30,270 They aren't producing a lot 59 00:02:30,270 --> 00:02:31,640 of propagules in and of themselves. 60 00:02:31,640 --> 00:02:33,030 And so those source populations 61 00:02:33,030 --> 00:02:35,920 or those source habitats are supporting populations growing 62 00:02:35,920 --> 00:02:37,070 in these sink habitats. 63 00:02:38,110 --> 00:02:41,270 And so this can happen on various spatial scales 64 00:02:41,270 --> 00:02:44,410 from landscape level to micro in terms of meters, 65 00:02:44,410 --> 00:02:46,490 depending on whatever is biologically relevant 66 00:02:46,490 --> 00:02:48,540 for the species of interest. 67 00:02:48,540 --> 00:02:51,380 And so this theory 68 00:02:51,380 --> 00:02:55,210 and this theoretical underpinning is particularly relevant 69 00:02:55,210 --> 00:02:58,280 to one species of interest, 70 00:02:58,280 --> 00:02:59,620 I'm sure to possibly many 71 00:02:59,620 --> 00:03:01,760 of you and many people who are interested 72 00:03:01,760 --> 00:03:03,620 in conserving New England forest. 73 00:03:03,620 --> 00:03:05,500 Specifically I'm talking about garlic mustard. 74 00:03:05,500 --> 00:03:09,560 And so you can see garlic mustard growing in both pictures. 75 00:03:09,560 --> 00:03:10,393 And the picture 76 00:03:10,393 --> 00:03:14,480 on the left is sort of the traditional habitat or areas, 77 00:03:14,480 --> 00:03:16,020 the source areas 78 00:03:16,020 --> 00:03:18,000 that we would think of garlic mustard growing. 79 00:03:18,000 --> 00:03:20,820 So sort of these highlight availability environments 80 00:03:20,820 --> 00:03:24,100 that are along anthropogenically disturbed areas, 81 00:03:24,100 --> 00:03:26,744 so parking lots, roads, trails, 82 00:03:26,744 --> 00:03:29,310 places that humans are fairly 83 00:03:29,310 --> 00:03:32,470 consistently disturbing the area and present. 84 00:03:32,470 --> 00:03:36,480 However, within over the past few decades, 85 00:03:36,480 --> 00:03:38,620 garlic mustard has been growing 86 00:03:38,620 --> 00:03:40,810 in much less disturbed areas, 87 00:03:40,810 --> 00:03:43,070 which with less light availability, 88 00:03:43,070 --> 00:03:44,550 and the exact mechanism 89 00:03:44,550 --> 00:03:46,750 or reason for this is really unknown. 90 00:03:46,750 --> 00:03:47,583 But so the picture 91 00:03:47,583 --> 00:03:50,140 on the right shows garlic mustard completely invading 92 00:03:50,990 --> 00:03:53,480 what is generally an intact forest understory, 93 00:03:53,480 --> 00:03:55,450 intact meaning less anthropogenically disturbed. 94 00:03:55,450 --> 00:03:56,400 It's not next to, 95 00:03:56,400 --> 00:03:57,950 right next to a road or a parking lot 96 00:03:57,950 --> 00:03:59,100 or something like that. 97 00:04:01,880 --> 00:04:04,290 And so broadly we know 98 00:04:04,290 --> 00:04:08,140 that garlic mustard is found across most of New England 99 00:04:08,140 --> 00:04:10,760 and much of the United States and North America in general. 100 00:04:10,760 --> 00:04:12,760 So anywhere from the Pacific Northwest 101 00:04:12,760 --> 00:04:14,200 through much of the Midwest, 102 00:04:14,200 --> 00:04:17,640 and as you can see most of New England. 103 00:04:17,640 --> 00:04:18,930 However, maps like this, 104 00:04:18,930 --> 00:04:20,420 which is what you traditionally see 105 00:04:20,420 --> 00:04:23,730 for sort of these range maps of species of interest, 106 00:04:23,730 --> 00:04:28,380 aren't showing that the scale which I was talking about, 107 00:04:28,380 --> 00:04:30,340 which relates to source-sink dynamics 108 00:04:30,340 --> 00:04:32,580 or habitat suitability, 109 00:04:32,580 --> 00:04:34,820 this is just simply showing like broadly geographically 110 00:04:34,820 --> 00:04:36,200 where a species is located, 111 00:04:36,200 --> 00:04:37,240 but within the counties, 112 00:04:37,240 --> 00:04:41,457 which is sort of the the boundaries of geographic 113 00:04:42,648 --> 00:04:45,250 where the species is found 114 00:04:45,250 --> 00:04:47,050 and how this map is like broken out, 115 00:04:48,210 --> 00:04:50,860 this is simply showing like broadly it's found in a county. 116 00:04:50,860 --> 00:04:52,800 It's not showing the habitat types 117 00:04:52,800 --> 00:04:55,190 or the habitats that garlic mustard is found in 118 00:04:55,190 --> 00:04:56,723 within those counties. 119 00:04:58,250 --> 00:04:59,573 And so a little bit more, 120 00:05:00,490 --> 00:05:03,010 and so I'm sort of interested in pulling that apart. 121 00:05:03,010 --> 00:05:06,330 And so a little bit more background on my study species. 122 00:05:06,330 --> 00:05:07,640 So garlic mustard 123 00:05:07,640 --> 00:05:10,300 or Alliaria petiolata is also called "jack by the hedge" 124 00:05:10,300 --> 00:05:11,777 in its native range, 125 00:05:13,246 --> 00:05:14,397 and so garlic mustard is native 126 00:05:14,397 --> 00:05:17,758 to Eurasia and Northern Africa, 127 00:05:17,758 --> 00:05:19,470 and its native range Alliaria petiolata 128 00:05:19,470 --> 00:05:22,100 or garlic mustard usually grows in hedgy areas. 129 00:05:22,100 --> 00:05:24,150 So sort of along those forest edges, 130 00:05:24,150 --> 00:05:29,110 along those areas of sort of dense vegetation, 131 00:05:29,110 --> 00:05:32,330 and often in anthropogenically-disturbed areas. 132 00:05:32,330 --> 00:05:36,003 So it was first recorded in the US circa 1868 in New York. 133 00:05:37,240 --> 00:05:41,210 And it's particularly problematic and of interest 134 00:05:41,210 --> 00:05:44,020 to many New England conservationists and land managers 135 00:05:44,020 --> 00:05:45,190 because it disrupts above 136 00:05:45,190 --> 00:05:47,120 and below ground community composition. 137 00:05:47,120 --> 00:05:50,630 So it disrupts native diversity 138 00:05:50,630 --> 00:05:52,480 and it does this in ways that we can see 139 00:05:52,480 --> 00:05:54,060 and in ways that we can't see, 140 00:05:54,060 --> 00:05:58,830 and this species does this because it disrupts associations 141 00:05:58,830 --> 00:06:01,340 between arbuscular mycorrhiza fungi found in this whale 142 00:06:01,340 --> 00:06:03,960 and native species that often critically depend 143 00:06:03,960 --> 00:06:07,150 on that AMF for survival. 144 00:06:07,150 --> 00:06:08,611 And so the impacts 145 00:06:08,611 --> 00:06:13,560 of especially the microbial disruption can last for years, 146 00:06:13,560 --> 00:06:15,533 and there's even some evidence to show 147 00:06:15,533 --> 00:06:19,760 that areas can't ever recover 148 00:06:19,760 --> 00:06:22,220 to a point of pre invaded status. 149 00:06:22,220 --> 00:06:24,190 But this could obviously vary depending on areas 150 00:06:24,190 --> 00:06:25,573 and lots of factors. 151 00:06:26,550 --> 00:06:27,440 And the picture 152 00:06:27,440 --> 00:06:31,450 on the right just generally shows very broadly 153 00:06:31,450 --> 00:06:33,790 where garlic mustard is found in its native range, 154 00:06:33,790 --> 00:06:38,630 so Eurasia, and in its invaded range, North America, 155 00:06:38,630 --> 00:06:41,530 and it also shows, which I want to specifically call out, 156 00:06:41,530 --> 00:06:44,800 sort of the morphological structures. 157 00:06:44,800 --> 00:06:49,800 So garlic mustard is a small herbaceous ground cover plant. 158 00:06:49,890 --> 00:06:51,490 It has a biennial life cycle. 159 00:06:51,490 --> 00:06:53,680 So its entire life cycle takes place 160 00:06:53,680 --> 00:06:56,030 within two growing seasons or two summers 161 00:06:56,030 --> 00:06:58,200 to over two years before it dies. 162 00:06:58,200 --> 00:07:00,538 Right before it dies, it naturally, 163 00:07:00,538 --> 00:07:02,430 or right before it naturally senescence, 164 00:07:02,430 --> 00:07:06,040 it releases a large amount of propagules, 165 00:07:06,040 --> 00:07:09,283 anywhere between a thousand to tens of thousands of seeds, 166 00:07:10,620 --> 00:07:12,030 but because this will be relevant 167 00:07:12,030 --> 00:07:14,680 to some of my analyses later on that I'm going to present, 168 00:07:14,680 --> 00:07:16,090 I wanted to call out the fact 169 00:07:16,090 --> 00:07:19,700 that garlic mustard has various distinct sort 170 00:07:19,700 --> 00:07:20,860 of morphological structures 171 00:07:20,860 --> 00:07:22,350 throughout its various life stages, 172 00:07:22,350 --> 00:07:24,220 and I specifically wanted to call out 173 00:07:24,220 --> 00:07:25,580 in its first growing season 174 00:07:25,580 --> 00:07:28,040 it has this basil rosette structure, 175 00:07:28,040 --> 00:07:29,747 and then in its second growing season, 176 00:07:29,747 --> 00:07:31,810 its second year of life before natural senescence, 177 00:07:31,810 --> 00:07:35,160 it produces these flowering stocks or reproductive stocks 178 00:07:35,160 --> 00:07:39,270 which house the siliques or fruits which have seeds in them. 179 00:07:39,270 --> 00:07:40,630 And so those siliques are those sort 180 00:07:40,630 --> 00:07:44,163 of narrow yellowy green tissues. 181 00:07:47,050 --> 00:07:51,040 And so specifically with my research project, 182 00:07:51,040 --> 00:07:53,390 I was interested in broadly seeing 183 00:07:53,390 --> 00:07:55,390 how source-sink dynamics plays a role 184 00:07:55,390 --> 00:07:58,430 in A. petiolata success in forest understories 185 00:07:58,430 --> 00:08:02,030 and how that relates to long-term success 186 00:08:02,030 --> 00:08:04,610 and possible management strategies. 187 00:08:04,610 --> 00:08:07,100 And so the specific research questions I asked to get at 188 00:08:07,100 --> 00:08:11,370 that broader interest was does garlic mustard performance, 189 00:08:11,370 --> 00:08:14,460 biomass, allocation, growth and reproductive capacity differ 190 00:08:14,460 --> 00:08:16,060 across forest growth microhabitats? 191 00:08:16,060 --> 00:08:17,700 Which I will show you pictures of what I mean 192 00:08:17,700 --> 00:08:19,700 by these microhabitats in just a second. 193 00:08:20,660 --> 00:08:23,310 And two are there demographic differences 194 00:08:23,310 --> 00:08:25,190 among populations of garlic mustard growing 195 00:08:25,190 --> 00:08:27,930 across microhabitats and over time? 196 00:08:27,930 --> 00:08:29,610 So specifically I was trying to get 197 00:08:29,610 --> 00:08:31,590 at demographic differences 198 00:08:31,590 --> 00:08:35,025 across multiple complete life cycles, 199 00:08:35,025 --> 00:08:37,283 meaning two year periods. 200 00:08:38,570 --> 00:08:42,790 Okay, and so to answer these questions, 201 00:08:42,790 --> 00:08:47,040 I needed to identify focal microhabitats and areas 202 00:08:47,040 --> 00:08:49,430 where I could establish long-term monitoring plots. 203 00:08:49,430 --> 00:08:51,200 And when I say I would establish them, 204 00:08:51,200 --> 00:08:52,970 I really mean my advisor. 205 00:08:52,970 --> 00:08:55,990 So I did this project in conjunction the coauthor 206 00:08:55,990 --> 00:08:58,480 of this talk who originally established these sites. 207 00:08:58,480 --> 00:08:59,810 Otherwise I would not have been able 208 00:08:59,810 --> 00:09:01,950 to do a long-term monitoring project 209 00:09:01,950 --> 00:09:03,733 within a master's degree. 210 00:09:04,720 --> 00:09:06,610 So specifically what I'm talking about, 211 00:09:06,610 --> 00:09:09,920 forest microhabitats, I mean the forest edge, 212 00:09:09,920 --> 00:09:11,710 the forest understory 213 00:09:11,710 --> 00:09:14,310 and sort of an intermediate transition zone between the two. 214 00:09:14,310 --> 00:09:16,190 And so these pictures are either of 215 00:09:16,190 --> 00:09:19,590 or right next to my actual sampling locations, 216 00:09:19,590 --> 00:09:21,290 which I'll show a little bit more information 217 00:09:21,290 --> 00:09:22,730 about in a second, 218 00:09:22,730 --> 00:09:24,710 but so the picture on the left shows 219 00:09:24,710 --> 00:09:26,630 what I mean by forest edge. 220 00:09:26,630 --> 00:09:29,860 So it's an area that's right at the forest edge 221 00:09:29,860 --> 00:09:32,190 where the tree cover, 222 00:09:32,190 --> 00:09:34,587 where there's a high canopy cover, 223 00:09:34,587 --> 00:09:37,760 but most of the area actually has highlight availability. 224 00:09:37,760 --> 00:09:39,710 It's not over shaded by the canopy. 225 00:09:39,710 --> 00:09:41,360 It's mostly herbaceous ground cover, 226 00:09:41,360 --> 00:09:42,670 very little leaf litter, 227 00:09:42,670 --> 00:09:44,930 and generally a lot of anthropogenic activities. 228 00:09:44,930 --> 00:09:47,934 So close to people's yards and your roads, 229 00:09:47,934 --> 00:09:49,750 and so generally there's some sort 230 00:09:49,750 --> 00:09:51,640 of activity happening there. 231 00:09:51,640 --> 00:09:54,680 These intermediate transition zones are areas right 232 00:09:54,680 --> 00:09:57,180 on the other side of that tree line. 233 00:09:57,180 --> 00:09:59,530 So generally there's a mix of herbacious 234 00:09:59,530 --> 00:10:01,030 and woody groundcover. 235 00:10:01,030 --> 00:10:02,657 There's leaf litter on the ground. 236 00:10:02,657 --> 00:10:06,100 There's oftentimes some amount of anthropogenic activity 237 00:10:06,100 --> 00:10:10,350 or evidence of trash or some sort of disturbance. 238 00:10:10,350 --> 00:10:15,350 And there's semi-mature to mature trees creating some amount 239 00:10:15,740 --> 00:10:18,530 of canopy cover and reducing light availability. 240 00:10:18,530 --> 00:10:20,710 And so when I say forest understory, 241 00:10:20,710 --> 00:10:22,560 the picture on the right, 242 00:10:22,560 --> 00:10:24,760 I'm generally talking about areas 243 00:10:24,760 --> 00:10:26,950 that are past these intermediate zones, 244 00:10:26,950 --> 00:10:28,000 where there is little 245 00:10:28,000 --> 00:10:30,410 to no evidence of anthropogenic activity, 246 00:10:30,410 --> 00:10:33,130 there's high leaf litter, very little ground cover, 247 00:10:33,130 --> 00:10:35,050 especially herbaceous ground cover, 248 00:10:35,050 --> 00:10:36,040 and the ground cover 249 00:10:36,040 --> 00:10:38,020 that is there is usually native tree seedlings 250 00:10:38,020 --> 00:10:40,050 that are just starting to grow, 251 00:10:40,050 --> 00:10:42,410 and there's generally mature trees 252 00:10:42,410 --> 00:10:45,853 with a lot of canopy cover and low light availability. 253 00:10:47,370 --> 00:10:51,790 And so specifically to get at both the spatial 254 00:10:51,790 --> 00:10:54,310 and like temporal sampling scheme 255 00:10:54,310 --> 00:10:55,960 that I briefly mentioned earlier, 256 00:10:56,909 --> 00:11:01,909 I established long-term management plots 257 00:11:04,506 --> 00:11:06,210 at the Harvard Forest, 258 00:11:06,210 --> 00:11:09,590 for anyone who is familiar with that site, 259 00:11:09,590 --> 00:11:13,140 and measured various environmental variables, 260 00:11:13,140 --> 00:11:16,987 individual plant performance, and population demography, 261 00:11:16,987 --> 00:11:19,570 both between 2003 and 2006, 262 00:11:19,570 --> 00:11:21,490 so I'll refer to that as sampling period one, 263 00:11:21,490 --> 00:11:24,333 and between 2015 and 2016, sampling period two. 264 00:11:28,460 --> 00:11:30,020 And so I just want to briefly call out that one 265 00:11:30,020 --> 00:11:33,260 of the responses I'm about to show you largely depends 266 00:11:33,260 --> 00:11:35,303 on that sort of life stage, 267 00:11:36,890 --> 00:11:40,530 that various life stage structure that I mentioned earlier. 268 00:11:40,530 --> 00:11:42,880 So you can measure based on survival proportions 269 00:11:42,880 --> 00:11:44,480 between those different life stages 270 00:11:44,480 --> 00:11:46,670 through seedlings, rosettes, and reproductive adults. 271 00:11:46,670 --> 00:11:49,540 You can get at specific rate of replacements 272 00:11:49,540 --> 00:11:51,290 or how an individual 273 00:11:51,290 --> 00:11:54,100 on average contributes to the next generation. 274 00:11:54,100 --> 00:11:55,330 And so I'm happy to answer questions 275 00:11:55,330 --> 00:11:57,590 about that more in just a second, 276 00:11:57,590 --> 00:11:58,990 but so the first result I want 277 00:11:58,990 --> 00:12:00,350 to show you is light availability 278 00:12:00,350 --> 00:12:01,540 across these microhabitats. 279 00:12:01,540 --> 00:12:03,250 So just confirming that 280 00:12:03,250 --> 00:12:04,860 because light is really important 281 00:12:04,860 --> 00:12:07,260 for garlic mustard growth and reproduction, 282 00:12:07,260 --> 00:12:09,020 we know this from various studies, 283 00:12:09,020 --> 00:12:10,770 that these edge habitats do have more light. 284 00:12:10,770 --> 00:12:13,270 So theoretically they are higher quality habitat. 285 00:12:13,270 --> 00:12:14,630 And that the intermediate sites 286 00:12:14,630 --> 00:12:17,170 and forest sites have less light availability, 287 00:12:17,170 --> 00:12:19,190 although it does not represent a gradient 288 00:12:19,190 --> 00:12:20,510 from edge to understory, 289 00:12:20,510 --> 00:12:22,460 the intermediate and forest sites have the same amount 290 00:12:22,460 --> 00:12:25,030 of light availability across two separate metrics, 291 00:12:25,030 --> 00:12:28,963 both photosynthetically active radiation and canopy cover. 292 00:12:30,480 --> 00:12:32,070 And so I'm going to show you some plant performance 293 00:12:32,070 --> 00:12:34,940 and trait variation data just really quickly. 294 00:12:34,940 --> 00:12:36,870 And so by plant performance 295 00:12:36,870 --> 00:12:39,020 and trait variation I measured multiple metrics 296 00:12:39,020 --> 00:12:42,170 for growth, such as height of second-year plants, 297 00:12:42,170 --> 00:12:45,610 and harvested adult plants right before natural senescence, 298 00:12:45,610 --> 00:12:47,600 dried the tissues in drying ovens, 299 00:12:47,600 --> 00:12:50,300 and got various metrics for total biomass, 300 00:12:50,300 --> 00:12:52,010 reproductive biomass, and things 301 00:12:52,010 --> 00:12:54,390 like reproductive to vegetative tissue ratios, 302 00:12:54,390 --> 00:12:56,610 because that can help us get at reproductive capacity 303 00:12:56,610 --> 00:12:58,583 outside of just simple seed production. 304 00:12:59,760 --> 00:13:02,380 And so for the graph, before I show you the actual data, 305 00:13:02,380 --> 00:13:04,530 I just wanted to orient you to the axes. 306 00:13:04,530 --> 00:13:07,220 So the top panel is adult height. 307 00:13:07,220 --> 00:13:09,240 So just simply the height from the bottom of the plant 308 00:13:09,240 --> 00:13:11,500 to the tip top of the reproductive stalk 309 00:13:11,500 --> 00:13:13,830 for an adult second second-year plant. 310 00:13:13,830 --> 00:13:14,890 The middle panel is the number 311 00:13:14,890 --> 00:13:18,060 of fruits produced per plant, just simple count numbers. 312 00:13:18,060 --> 00:13:19,610 And then the bottom panel is the number 313 00:13:19,610 --> 00:13:20,443 of branches per plant. 314 00:13:20,443 --> 00:13:22,310 So just another metric for general growth. 315 00:13:22,310 --> 00:13:24,760 And then along the x-axis, you have the edge, 316 00:13:24,760 --> 00:13:27,300 the intermediate, and the forest microhabitats. 317 00:13:27,300 --> 00:13:30,000 And so all of this data is pooled across all 318 00:13:30,000 --> 00:13:33,350 of those sampling periods that I had mentioned earlier. 319 00:13:33,350 --> 00:13:36,423 And as you can see, not surprisingly, 320 00:13:37,630 --> 00:13:39,070 sort of what we were expecting, 321 00:13:39,070 --> 00:13:40,790 'cause we were expecting these edge microhabitats 322 00:13:40,790 --> 00:13:43,020 to be these source populations based simply 323 00:13:43,020 --> 00:13:44,380 on light availability and the fact 324 00:13:44,380 --> 00:13:46,900 that they're more anthropogenically disturbed. 325 00:13:46,900 --> 00:13:50,258 The results do confirm that the edge microhabitats, 326 00:13:50,258 --> 00:13:52,690 when we pulled all of this data across years, 327 00:13:52,690 --> 00:13:54,180 showed that plants across all 328 00:13:54,180 --> 00:13:57,090 of these metrics were the largest and perform the best. 329 00:13:57,090 --> 00:13:59,910 And generally the forest plants performed the worst. 330 00:13:59,910 --> 00:14:02,590 Although in one metric for adult height, 331 00:14:02,590 --> 00:14:05,540 the intermediate and forest plans performed about the same. 332 00:14:06,970 --> 00:14:11,890 So moving on to per plant biomass, 333 00:14:11,890 --> 00:14:14,700 total biomass is this top panel on the left, 334 00:14:14,700 --> 00:14:18,750 reproductive biomass, meaning the entire biomass 335 00:14:18,750 --> 00:14:22,420 of fruiting tissue, seeds, and any flowering tissues 336 00:14:22,420 --> 00:14:23,820 that were harvested, 337 00:14:23,820 --> 00:14:27,050 and then reproductive to vegetative biomass ratios. 338 00:14:27,050 --> 00:14:29,649 So simply all vegetative tissues compared 339 00:14:29,649 --> 00:14:31,860 to all reproductive tissues, 340 00:14:31,860 --> 00:14:35,290 which I just mentioned what that was a second ago. 341 00:14:35,290 --> 00:14:37,190 And so again, you see the same sort of trend 342 00:14:37,190 --> 00:14:39,550 for total and reproductive biomass, 343 00:14:39,550 --> 00:14:42,700 where the edge plants were the largest, performed the best, 344 00:14:42,700 --> 00:14:46,710 the intermediate sites had intermediate-sized plants, 345 00:14:46,710 --> 00:14:50,500 and then the forest sites had the smallest plants. 346 00:14:50,500 --> 00:14:51,630 What's particularly interesting, 347 00:14:51,630 --> 00:14:53,280 and what I want to call your attention to 348 00:14:53,280 --> 00:14:55,220 on the graph on the right, 349 00:14:55,220 --> 00:14:56,053 is that the edge 350 00:14:56,053 --> 00:14:58,050 and the intermediate plants actually allocated 351 00:14:58,050 --> 00:15:02,670 about the same amount of tissue 352 00:15:02,670 --> 00:15:04,510 or about the same amount of resources 353 00:15:04,510 --> 00:15:06,840 to reproductive tissues. 354 00:15:06,840 --> 00:15:09,810 However, the forest plants showed decreased allocation 355 00:15:09,810 --> 00:15:11,010 to reproductive tissues, 356 00:15:12,320 --> 00:15:13,760 possibly indicating that 357 00:15:13,760 --> 00:15:15,390 this environment was really low quality 358 00:15:15,390 --> 00:15:16,410 and the plants were stressed out 359 00:15:16,410 --> 00:15:17,880 before they could get to that second year 360 00:15:17,880 --> 00:15:21,210 to be able to produce seeds and reproductive tissues. 361 00:15:21,210 --> 00:15:23,810 And so this is sort of showing the exact same story, 362 00:15:25,846 --> 00:15:29,920 that plants in the edge across time. 363 00:15:29,920 --> 00:15:33,330 So the x-axis now shows 2004 and 2016. 364 00:15:33,330 --> 00:15:34,163 So bringing in a little bit 365 00:15:34,163 --> 00:15:36,810 of that temporal component is showing 366 00:15:36,810 --> 00:15:39,300 that again the edge plants produced the most number 367 00:15:39,300 --> 00:15:40,920 of seeds consistently across time, 368 00:15:40,920 --> 00:15:42,800 although there is some variation. 369 00:15:42,800 --> 00:15:45,160 The intermediate plants produced an intermediate amount 370 00:15:45,160 --> 00:15:48,150 of seeds and the forest plants produced the fewest, 371 00:15:48,150 --> 00:15:50,680 and you can see the P values were significant 372 00:15:50,680 --> 00:15:52,510 for both the effect of microhabitat, 373 00:15:52,510 --> 00:15:54,080 the effect of year, 374 00:15:54,080 --> 00:15:56,993 and the interactive effect of microhabitat and year. 375 00:16:00,090 --> 00:16:01,760 And so just to quickly go over some 376 00:16:01,760 --> 00:16:04,360 of the demographic responses that I measured, 377 00:16:04,360 --> 00:16:08,010 I'm going to show you a graph that is plant density 378 00:16:08,010 --> 00:16:09,070 for various life stages. 379 00:16:09,070 --> 00:16:11,350 So just the number of plants per square meter. 380 00:16:11,350 --> 00:16:13,280 And then population growth rate or lambda 381 00:16:13,280 --> 00:16:15,530 for anyone who's familiar with that analysis. 382 00:16:16,370 --> 00:16:19,740 So similarly following the trends that I just showed you 383 00:16:19,740 --> 00:16:22,014 for individual plant performance, 384 00:16:22,014 --> 00:16:24,461 most of the life stages 385 00:16:24,461 --> 00:16:27,530 for especially seedling density and rosette density, 386 00:16:27,530 --> 00:16:30,450 so those earlier life stages which take place 387 00:16:30,450 --> 00:16:31,580 within the first growing season 388 00:16:31,580 --> 00:16:34,080 and at the very beginning of the second growing season, 389 00:16:34,080 --> 00:16:37,020 plants had the highest densities in the edge, 390 00:16:37,020 --> 00:16:40,150 which you can see by this gray circle, 391 00:16:40,150 --> 00:16:41,410 both in sampling period one, 392 00:16:41,410 --> 00:16:44,640 which was any data collected between 2003 and 2006, 393 00:16:44,640 --> 00:16:45,910 and for sampling period two, 394 00:16:45,910 --> 00:16:48,500 which was data collected in 2015 and 2016. 395 00:16:48,500 --> 00:16:50,490 However, the fruiting adult density, 396 00:16:50,490 --> 00:16:52,800 this story isn't quite as clear 397 00:16:52,800 --> 00:16:54,850 but there was significant declines 398 00:16:54,850 --> 00:16:57,730 for all microhabitat types in sampling period two. 399 00:16:57,730 --> 00:16:59,670 I think that's probably 400 00:16:59,670 --> 00:17:02,610 because sampling period two unfortunately was 401 00:17:02,610 --> 00:17:04,670 during some pretty dry conditions. 402 00:17:04,670 --> 00:17:08,350 So I think just generally plants weren't able to survive 403 00:17:08,350 --> 00:17:10,050 in those really dry hot conditions 404 00:17:11,250 --> 00:17:13,260 in any of the microhabitats. 405 00:17:13,260 --> 00:17:15,520 So the last piece of data that I'm going to show you 406 00:17:15,520 --> 00:17:18,560 before wrapping up is population growth rate, 407 00:17:18,560 --> 00:17:19,830 and so the population growth rate 408 00:17:19,830 --> 00:17:22,600 or lambda is essentially a rate of replacement, 409 00:17:22,600 --> 00:17:24,940 an average rate of replacement for an individual, 410 00:17:24,940 --> 00:17:26,350 meaning one individual 411 00:17:26,350 --> 00:17:28,830 in the current generation is going to produce 412 00:17:28,830 --> 00:17:31,920 how many individuals on average in the next generation. 413 00:17:31,920 --> 00:17:34,400 So going off of that logic, 414 00:17:34,400 --> 00:17:36,330 a stable population size would mean 415 00:17:36,330 --> 00:17:38,840 that one plant in this generation would produce 416 00:17:38,840 --> 00:17:40,890 on average one plant in the next generation, 417 00:17:40,890 --> 00:17:43,260 but if they're producing more than one plant 418 00:17:43,260 --> 00:17:44,093 in the next generation, 419 00:17:44,093 --> 00:17:46,350 the populations are predicted to grow, 420 00:17:46,350 --> 00:17:48,450 and if they're going to produce slightly less 421 00:17:48,450 --> 00:17:51,350 or way less than one individual in the next generation, 422 00:17:51,350 --> 00:17:53,700 the population sizes are predicted to decrease. 423 00:17:53,700 --> 00:17:55,571 So what's really important is that anything above 424 00:17:55,571 --> 00:17:58,070 this horizontal green line means 425 00:17:58,070 --> 00:18:01,010 that populations are still predicted to increase in size 426 00:18:01,010 --> 00:18:03,050 and anything below that one means 427 00:18:03,050 --> 00:18:05,130 that populations are predicted to decrease, 428 00:18:05,130 --> 00:18:08,900 and so what we found looking across space and time 429 00:18:08,900 --> 00:18:10,757 between sampling period one in the early 2000s 430 00:18:10,757 --> 00:18:14,230 and sampling period two in 2015-2016 431 00:18:14,230 --> 00:18:15,560 and across microhabitats, 432 00:18:15,560 --> 00:18:18,770 so the edge, the lighter gray, the intermediate, 433 00:18:18,770 --> 00:18:20,510 the medium gray triangles, 434 00:18:20,510 --> 00:18:23,830 and in the forest these darker gray squares, 435 00:18:23,830 --> 00:18:25,880 was that the intermediate populations 436 00:18:25,880 --> 00:18:28,120 are stable across time. 437 00:18:28,120 --> 00:18:31,130 The edge populations have the highest rate of replacement, 438 00:18:31,130 --> 00:18:34,620 and even though they have declined between sampling periods, 439 00:18:34,620 --> 00:18:35,645 their individual rate 440 00:18:35,645 --> 00:18:37,970 of replacement is still well above one. 441 00:18:37,970 --> 00:18:40,370 So the populations are still predicted to increase. 442 00:18:40,370 --> 00:18:42,900 However, the forest populations, 443 00:18:42,900 --> 00:18:46,310 while sampling in sampling period one they were above one, 444 00:18:46,310 --> 00:18:48,980 have significantly declined far below one 445 00:18:48,980 --> 00:18:51,000 and are predicted to decrease. 446 00:18:51,000 --> 00:18:53,800 And I specifically just want to call out using the last 447 00:18:53,800 --> 00:18:55,200 like 10 seconds that I have 448 00:18:55,200 --> 00:18:56,970 that these declines between the edge 449 00:18:56,970 --> 00:19:01,150 and forest populations track really closely, 450 00:19:01,150 --> 00:19:03,000 which is sort of a little bit more evidence 451 00:19:03,000 --> 00:19:07,720 that the edge microhabitat could be sourcing propagules 452 00:19:07,720 --> 00:19:10,040 into the forest understory. 453 00:19:10,040 --> 00:19:12,690 So just in sort of summary, the edge microhabitat, 454 00:19:12,690 --> 00:19:14,560 it was found to be the most optimal 455 00:19:14,560 --> 00:19:16,350 for plant performance growth and fecundity 456 00:19:16,350 --> 00:19:17,950 across multiple metrics. 457 00:19:17,950 --> 00:19:19,980 Forest plants show depressed growth and performance 458 00:19:19,980 --> 00:19:22,190 with less allocation to reproduction. 459 00:19:22,190 --> 00:19:23,580 Garlic mustards are still growing 460 00:19:23,580 --> 00:19:27,440 in the forest edge and intermediate microhabitats, 461 00:19:27,440 --> 00:19:30,430 but they are predicted to decline in the forest sites. 462 00:19:30,430 --> 00:19:31,760 And source-sink population dynamics 463 00:19:31,760 --> 00:19:33,020 are likely playing a role 464 00:19:33,020 --> 00:19:35,310 into garlic Mustard's incursion into New England forests 465 00:19:35,310 --> 00:19:37,780 at least within this one tract of land 466 00:19:37,780 --> 00:19:39,090 that I was looking at. 467 00:19:39,090 --> 00:19:40,030 And because of that, 468 00:19:40,030 --> 00:19:42,380 management efforts should consider invasion 469 00:19:42,380 --> 00:19:44,870 across these heterogeneous habitats, 470 00:19:44,870 --> 00:19:46,230 because like I mentioned earlier 471 00:19:46,230 --> 00:19:48,170 and just sort of reiterating that graph 472 00:19:48,170 --> 00:19:49,610 from the introduction, 473 00:19:49,610 --> 00:19:51,610 source sites are producing propagules, 474 00:19:51,610 --> 00:19:54,420 which then go into these sink sites. 475 00:19:54,420 --> 00:19:56,290 So decreasing propagule pressure 476 00:19:56,290 --> 00:19:57,980 within source sites could lead 477 00:19:57,980 --> 00:19:59,570 to extinctions of populations 478 00:19:59,570 --> 00:20:01,410 or at least decreases in population size 479 00:20:01,410 --> 00:20:02,653 within the sink sites. 480 00:20:04,750 --> 00:20:06,990 And so with that acknowledgement, 481 00:20:06,990 --> 00:20:08,220 so I just want to thank my lab 482 00:20:08,220 --> 00:20:10,293 and I'm happy to take any questions. 483 00:20:12,950 --> 00:20:14,610 - [Facilitator] You have a question from John Cart. 484 00:20:14,610 --> 00:20:18,680 So what do I do if I'm managing a small riparian site 485 00:20:18,680 --> 00:20:20,463 with an established infestation? 486 00:20:22,860 --> 00:20:24,605 - So that's a great question. 487 00:20:24,605 --> 00:20:29,605 I do not specifically study sort of management responses, 488 00:20:30,450 --> 00:20:31,283 so I'm not sure 489 00:20:31,283 --> 00:20:32,920 if I would be the best person to answer that, 490 00:20:32,920 --> 00:20:34,250 but I would say based on 491 00:20:34,250 --> 00:20:38,010 what my little experience I guess is with that, 492 00:20:38,010 --> 00:20:39,990 my lab mate's much more focused 493 00:20:39,990 --> 00:20:41,820 on sort of management efforts 494 00:20:41,820 --> 00:20:44,110 and the implications for garlic mustard populations. 495 00:20:44,110 --> 00:20:46,670 So what is effective management strategies? 496 00:20:46,670 --> 00:20:49,080 But within the context of what I presented, 497 00:20:49,080 --> 00:20:51,130 I would say that largely it has to do 498 00:20:51,130 --> 00:20:52,100 with what your goals are. 499 00:20:52,100 --> 00:20:54,420 So if it's to eradicate populations 500 00:20:54,420 --> 00:20:56,790 versus decrease the population size, 501 00:20:56,790 --> 00:20:59,480 if you're trying to bring back native species 502 00:20:59,480 --> 00:21:01,990 versus simply decrease the presence 503 00:21:01,990 --> 00:21:03,663 of garlic mustard in an area. 504 00:21:05,160 --> 00:21:08,320 And I think it also depends on, well, 505 00:21:08,320 --> 00:21:10,040 there's a lot of factors that have been shown 506 00:21:10,040 --> 00:21:11,980 to impact sort of invasion success. 507 00:21:11,980 --> 00:21:12,970 So the source-sink dynamics 508 00:21:12,970 --> 00:21:15,700 that I was presenting would just be one mechanism 509 00:21:15,700 --> 00:21:17,120 by which garlic mustard could be 510 00:21:17,120 --> 00:21:20,440 possibly successful invading say forest understories, 511 00:21:20,440 --> 00:21:22,820 or various other habitat types, 512 00:21:22,820 --> 00:21:27,660 but I think to be able to specifically answer your question, 513 00:21:27,660 --> 00:21:30,023 I would need sort of site specific information. 514 00:21:32,836 --> 00:21:34,620 I'm not sure if that really answers your question, 515 00:21:34,620 --> 00:21:38,260 but that's sort of what I can tell you I think based 516 00:21:38,260 --> 00:21:39,810 on the information that I have. 517 00:21:47,410 --> 00:21:48,243 - [Facilitator] Another question, 518 00:21:48,243 --> 00:21:50,300 which native species would do best 519 00:21:50,300 --> 00:21:52,463 at competing against garlic mustard? 520 00:21:54,330 --> 00:21:55,320 - That's a great question. 521 00:21:55,320 --> 00:21:58,790 So again, that's sort of outside of what I study. 522 00:21:58,790 --> 00:22:03,580 So I really do like population sort of population dynamics 523 00:22:03,580 --> 00:22:07,520 of species, but I would say that, 524 00:22:07,520 --> 00:22:09,930 so since garlic mustard is really good at disrupting 525 00:22:09,930 --> 00:22:12,620 like I said that AMF, the arbuscular mycorrhizal fungi, 526 00:22:12,620 --> 00:22:14,920 associations with native plant species, 527 00:22:14,920 --> 00:22:18,160 garlic mustard is non-mycorrhizal. 528 00:22:18,160 --> 00:22:19,930 So it doesn't need those associations. 529 00:22:19,930 --> 00:22:24,594 It would likely be species that are not going to be overly, 530 00:22:24,594 --> 00:22:27,170 that would not be dependent on AMF, 531 00:22:27,170 --> 00:22:30,500 that would not be overly browsed by say deer, 532 00:22:30,500 --> 00:22:31,740 because it's been shown 533 00:22:31,740 --> 00:22:35,210 that deer browsing also helps to contribute 534 00:22:35,210 --> 00:22:37,510 to garlic mustard's invasion success because especially 535 00:22:37,510 --> 00:22:40,440 like ungulates will preferentially browse native species 536 00:22:40,440 --> 00:22:41,390 over garlic mustard, 537 00:22:41,390 --> 00:22:44,260 which just increases its competitive ability. 538 00:22:44,260 --> 00:22:45,900 So I would say species that fall 539 00:22:45,900 --> 00:22:47,860 into those sorts of categories, 540 00:22:47,860 --> 00:22:52,860 not attractive to deer browsers or other native herbivores, 541 00:22:53,440 --> 00:22:55,913 not dependent on AMF associations. 542 00:22:56,780 --> 00:22:58,493 Hopefully that answers your question. 543 00:23:01,260 --> 00:23:02,630 - [Facilitator] Great. 544 00:23:02,630 --> 00:23:03,864 Another similar question 545 00:23:03,864 --> 00:23:06,710 in the very few remaining minutes, 546 00:23:06,710 --> 00:23:08,800 do you notice any other invasive species that seem 547 00:23:08,800 --> 00:23:10,763 to grow well alongside garlic mustard? 548 00:23:12,530 --> 00:23:14,160 - Yes, that's a great question. 549 00:23:14,160 --> 00:23:18,958 So specifically in the areas that I was in, no. 550 00:23:18,958 --> 00:23:20,800 Garlic mustard was pretty much 551 00:23:20,800 --> 00:23:23,010 the most pervasive invasive species. 552 00:23:23,010 --> 00:23:24,973 I know in other areas I've seen, 553 00:23:26,020 --> 00:23:28,240 especially Japanese knotweed, 554 00:23:28,240 --> 00:23:30,370 I'll see garlic mustard growing right along areas 555 00:23:30,370 --> 00:23:33,823 where just Japanese knotweed is in a massive monoculture. 556 00:23:36,990 --> 00:23:38,330 Also multiflora rose, 557 00:23:38,330 --> 00:23:40,330 I'll see that in association with garlic mustard 558 00:23:40,330 --> 00:23:41,510 in at least some of the areas 559 00:23:41,510 --> 00:23:44,160 that I've sort of anecdotally surveyed, 560 00:23:44,160 --> 00:23:45,380 but outside of that, no. 561 00:23:45,380 --> 00:23:47,090 But there is definitely evidence 562 00:23:47,090 --> 00:23:50,220 to show that garlic mustard does grow in areas 563 00:23:50,220 --> 00:23:53,090 with various other invasive species. 564 00:23:53,090 --> 00:23:55,290 But I can't necessarily tell you more specific information 565 00:23:55,290 --> 00:23:57,690 about if the invasive species, 566 00:23:57,690 --> 00:23:59,200 if there are specific invasive species 567 00:23:59,200 --> 00:24:01,733 it grows with commonly.