Unearthing Habitats: Transforming Sand Mines into Bee Havens (Ep. 57)

As our wild bee populations face worldwide declines, innovative approaches to conservation are more critical than ever. Dr. Nicola Seitz shares her remarkable findings of bee communities thriving in reclaimed sand mines and roadside meadows in Maryland. Surprising to many, reclaimed sand mines outshine roadside meadows in terms of bee diversity and abundance. Nicola explains how these seemingly barren landscapes can offer a promising future for bee conservation. Despite having less floral abundance, sand mines hosted a higher diversity of bee species than the adjacent meadows. A significant portion of their bee population consists of ground-nesting species, which find favorable nesting conditions in the open, sandy soil of abandoned mines.

Nicola conducted her PhD studies at the University of Maryland in the United States and the University of Würzburg in Germany. She has worked as a scientific counselor and in conservation management with a strong focus on connecting humans, data, and nature conservation. She currently works at the German Network for Plant Diversity. Read the full study we discussed here.

Nicola joined The Bee’s Knees to discuss the pollinator friendliness of native vs. non-native plants. For more listening on unconventional bee habitats, listen to our episode about quarries and one about pollinator-friendly solar farms.

Good to know

Despite their degraded appearance, reclaimed sand mines offer valuable nesting grounds for bees. Most bee species are ground nesters, and the loose, sandy soils in these sites provide ideal conditions for burrowing. As Nicola’s research found it was remarkable that even with limited floral resources, bee abundance and diversity thrived—particularly where vegetative cover was sparse, allowing more nesting access. Nicola also touched on the fact that scientists still lack nesting data for some species, underscoring how much remains to be discovered about bee ecology and the subtle needs of their habitats.

Transcript

Jacy: [00:00:00] Welcome to the Bees Knees a podcast wild about native bees. Wild and native bees are under threat worldwide. In each episode, we look at actionable things we can do to support these adorable little guys whose pollination work is crucial for maintaining biodiversity. I’m Jacy Meyer and I thank you for being here.

Last episode, we explored quarries and their surprising role in supporting wild bee populations, but they aren’t the only seemingly barren landscapes offering unexpected havens for pollinators. Sand mines too. Hold promise for bee conservation. Researchers have found that despite their human made origins, sand mines provide crucial nesting grounds for wild bees, including rare and declining species.

Today we’re joined by Dr. Nicola Seitz whose research on bee communities in reclaimed sand mines and roadside meadows in Maryland [00:01:00] unveils fascinating insights. We’ll discuss why sand mines might actually be better suited for bees than the adjacent meadows. How ground nesting species thrive in these spaces and the broader implications for conservation.

So what motivated you to explore bee Communities in Sand Mines and Roadside Meadows? Yes.

Nicola: So, uh, thank you first of all for inviting me once again to this podcast and I’m really happy to be able to speak about this study that I conducted where we compared. Reclaimed sand mine habitats as as bee habitats with roadside meadows.

And I think there were two main reasons that motivated me to conduct this study. First of all, I mean, overall I have been very much interested in bee conservation and due to. The declines of wild bee populations, I got [00:02:00] really interested in understanding better the actual habitat requirements that Wild Bees have.

And then the second reason was I spoke to Sam Droege, who is a bee expert. Working for the US Geological Survey and runs a bee lab in Maryland in the US where I also conducted my study. And so he told me that he thought he had the impression that there was a lot of bee activity in or around old sand mines.

And so I got really curious and he said, uh, though that no one had really. Really looked into this in a deeper way. So yeah, I thought this would be a very interesting study system and I wanted to assess the bee communities in those, uh, reclaimed set mines. But then for comparison, I wanted to compare it also to another bee habitat, and I decided to go [00:03:00] with roadside Meadows because this was all set in rural Maryland, where actually roadside meadows do represent a pretty.

Good bee habitat, let’s say, because they represent they’re like long meadows, like longer corridors with. Kind of diverse and abundant flora, and they’re also relatively undisturbed. So we knew already, okay, the roadside meadows are actually good, kind of bee habitat. So let’s compare that to the reclaimed sand mines.

And now I. Maybe I should also explain a little better what I mean by reclaimed sand mine. So sand mines are areas where certain soil layers are extracted, um, the sandy soil layers, and they’re used then, for example, for concrete production. And that is also why we do find them worldwide a lot. And then once the mining is finished, you are left with.[00:04:00]

Often empty, uh, pits in the landscape, and it depends on what they’re designated for then after the mining and if they’re being developed or not. But then some part of those are simply designated or left as green spaces, let’s say. And what that means is they usually add topsoil, which is typically taken from that site also.

So that is still very sandy soil, rather low in nutrients. Then they are usually required to seed that area. Um, there’s, in Maryland at least, there’s no specification what exactly they need to seed this area with. So this is often a very low plant diversity seed mix. Often also non-native plants. And I worked at three different sand mines, reclaimed sand mines, I should say in Maryland.

And then the roadside meadows, they were always adjacent to those sand mines. So just a few hundred meters away. And that’s important to know [00:05:00] because that means that in general they were, the both habitat types were in the same larger area, so they could be colonized potentially by the same pool of bee species.

Jacy: So you found perhaps, surprisingly, that the sand mines hosted a more diverse bee community compared to these adjacent roadside meadows. Why do you think the sand mine provided such a favorable environment for these wild bees? Yes, that

Nicola: is very interesting indeed. So maybe let’s start with just looking exactly at, we’ve found the differences that we’ve found.

So we found in fact. A higher number of bee species at the sand mines, which. Might be a bit surprising at first because we know, uh, we also recorded the flowering at both different habitats site. And of course, I mean, as expected we had more floral abundance and [00:06:00] diversity at the roadside meadows compared to the sand mine.

Still, we found many more bee species and more bee individuals at the sand mines. And it was not just more bees at the sand mines also, the species composition actually differed, uh, significantly differed between the two habitat types. So it was not that the meadows were just missing a few species, but really the bee species composition was different.

At the sand mines we had. 111 different bee species and at the roadsides 88 different bee species. I do not wanna say that roadside meadows were not a good bee habit. So yes, in my comparison, the sand mines had hosted a more diverse and more abundant bee community. That does not mean that the roadside meadows are are not a good habitat though.

They hosted 88 species, which is for Maryland, [00:07:00] where we have a total of 430 more or less bee species. That’s a fairly high number of bee species, and that is a very diverse bee community. I mean, that represents 20% of all Maryland bees. And yeah, given that this was only like one small habitat, that was already a very good result too.

When we then took an even deeper look into like what kind of bee species we found we, there was one very interesting uh, point, which was we analyzed them according to what their nesting behavior was. And what we found that actually in both habitat types, a large proportion of the bees, which was 63% were ground nesters.

So in that regard, both habitats were actually. Similar or, or the same, let’s say. However, when we then looked at the bee individuals and the [00:08:00] proportions of bees. Of those species, we found that the ground nesting bee species occurred in much higher numbers in both, uh, habitats, but then even more, a lot more at the sand mines.

So at the sand mines, 95% of individuals were ground nesting bees. So that’s really the vast majority. Uh, still at the roadside we also had a fairly high proportion of ground nesting bees. So even there we found 81% of the bees, to be uh, ground nesting. And yeah, so now we can see already, okay, maybe this has something to do with their nesting behavior.

And then of course, the nesting is also influenced by how much, uh, vegetation free ground we have. And so that was one of the variables that we looked at, and actually that was the Vegetational ground cover was the variable that best explained [00:09:00] the, bee abundance that we found, and also the bee species richness and the Shannon Diversity.

Jacy: So based on what you found, how can sand mines be managed or maybe modified to further support the conservation efforts? Are there specific practices you would recommend to land managers or the owners of these reclaimed sand mines?

Nicola: Yes. Uh, I think definitely we could do something about the floral resources, because in the end, yes, the nesting sites are very important and maybe more important than we have previously thought.

However, still, of course the bees also need some food. And right now, or at least that’s the situation in, in Maryland. There were, at the time of my study at least, those kind of low diversity seed mixes that were brought in. And then they even often contain non-native plants. And I [00:10:00] would really like. To see more spontaneous recolonization of native plants from the rims of those habitats.

And I think that would be really nice if we would allow more spontaneous, um, natural succession of these areas. However, if plans are brought in, I would strongly encourage to first of all, use uh, native plans. Native to that area. And then also in order to support the bees better, it would be a good idea to use some pollinator friendly plants.

Of course.

Jacy: So when thinking about. Conservation strategies, we could probably call, uh, sand mines an unconventional habitat. But given the ongoing decline of our wild bee populations, do you see a role for habitats like this fitting into broader strategies?

Nicola: Yes, [00:11:00] definitely. I think what this study clearly showed that also unconventional habitats and maybe also habitats that for us at first glance.

Do not even look at all like a valuable habitat can be valuable habitats for the bees and the main conservation efforts nowadays often focus on agricultural and urban context. And I think what this study has shown that simply open new perspectives and to look beyond those agriculture and, and urban contexts and yeah, so also other.

Anthropogenically altered habitats such as quarries or power lines, strips could be actually play important roles in the future. So where would you like

to

Jacy: see the research

Nicola: go in this

Jacy: area?

Nicola: I think we need to better understand the nesting requirements of bees. I mean, we have known for a long time that nesting, um, is [00:12:00] of course important for the bees also.

We have known for a long time that um, most bees are ground nesting bees more, much more than cavity nesters. Still a lot of research and conservation efforts have not taken this much into account or, or looked deeper. Also, in general, the research has focused. Much more on, uh, the flora resources, which of course are super, super important.

And there is still the need to find out more about bee nutrition too. Definitely. And that’s maybe another point that I would like to mention here, even in my study. There were four bee species of which the nesting behavior was simply not known. And so that already shows us, okay, there is a lack of knowledge here and that is something that deserves further attention.

Jacy: So if you could encourage people to do just one thing to support native bees, what would it be? [00:13:00]

Nicola: Well, I think as we have seen in this study, nesting sites are very important. So I would definitely encourage people to pay attention to that and maybe if possible, to provide some nesting sites. So even if you have your.

Own little backyard garden. Maybe consider leaving some patches of just barren ground where bees can nest and you will be surprised how quickly they actually come and use those spaces if they’re

Jacy: appropriate. A huge thank you to Nicola for this important reminder. Nature thrives in unexpected places when given the right conditions.

Her actionable advice. Remember, our ground nesters. bee hotels help, but most bee species prefer the comfort of bare ground, so let’s create more of those nesting spaces for them. Head to the Bees knees.website to find our previous episode with Nicola, where we talked about whether native and [00:14:00] non-native pollinator friendly plants offer equal value to wild bee communities.

Thank you for tuning in. If you enjoyed this episode, please consider sharing the bees knees with your friends. Until next time, keep looking for unexpected ways to support the bees.