Ed Tripp's blog

Temperature affects plant growth

The heather that I placed in sand in May has been growing well ever since.

The most striking thing is the difference in size of the plants between the different temperatures. The plants grown in the highest temperature are nearly twice the size of those grown in the coldest temperature (see pictures).

So if temperatures increased in the UK, some plants really would grow much faster, which might mean that some species do better than others under temperature increase. So the fingers of climate change touch far more than we might think.

Next week I will be harvesting the heather plants and measuring their weights to see if the plants from warmer temperatures, like Spain or Portugal, grow better in higher temperatures than those from colder climates, like Norway or Finland.

Here's to some more interesting data....

Climate Change and Heathland

So all the dirt collecting has been done. It took two months and a good few thousand miles to get there, but I finally collected the three hundred soil samples that I needed. I can now work in the lab to find out what my data is showing about enzymes in heathland soils, and how this might be affecting heathland plants.

However, my samples will keep for a while before I analyse them so now I have time for something completely different.

Climate change is affecting everyone. We know that temperatures may be increasing, and rainfall patterns may be changing. Plants notice the changes just as much as we do. With increases in temperature plants grow faster, getting bigger quicker. Heather, which is slow growing, does grow faster when it's warmer, but other plants would respond to a greater extent. Bracken, for example, grows much faster when it's warmer. So if temperatures did increase heather may be forced out by faster growing species like braken and grasses. This means that we might lose even more heathland!

So what can we do about it?
Heather is found in places that are hotter and colder than the UK, like Spain and Finland. These heather populations might have adapted over many years to grow better under local climate conditions. If so, can we not plant heather from a hotter place, like Spain, here in the UK? Might this give heather a better chance to survive because the plants will be used to the hotter weather. Let's find out!

The attached pictures show three growth rooms, each with different daytime temperatures (17, 20 and 23 degrees), full of tiny heather seedlings. These were grown from seed collected from all over Europe, including Spain, Portugal, France, Norway, Finland and Germany.

Over the next few months we will find out it the plants from warmer regions grow better under increased temperatures in relation to plants from colder regions. Let's hope so!

Here also is a picture of me delicately placing seedlings on sand, ready for the growth room.

Results from Results

One good thing about research is that new ideas can come from data collected earlier in the project. The heather experiments that I did right at the start of my project yielded some nice data about nitrogen and phosphorus uptake by the heather plants. So what was so interesting about this data? Well, it seemed that if nitrogen uptake by a plant increased with atmospheric nitrogen deposition, phosphorus uptake seemed to increase in exactly the same way across all heathlands studied. As phosphorus isn't deposited in the same way as nitrogen, these seemed like some unusual results.

There could be any number of reasons for these results. One possibility is that there is something in the soil that is upregulating phosphorus uptake by heather in relation to increased nitrogen deposition. There are a number of enzymes in the soil that could be doing just this, including a group of enzymes called phosphatases. These enzymes work in exactly the same way as enzymes in our own digestive system. They break down phosphorus in the soil to make it available to plants.

This sounded like an interesting hypothesis to investigate. But to do this I need fresh soil from all of my 26 heathland sites. Back into the field then! Five months of travelling from Scotland to Lundy Island, from Norfolk to Northumberland. Same story as before: get on my hands and knees, dig up soil with a trowel, sieve in the field, and bring back to the lab for analysis.

No hiccups so far, except of course for the major snow that we had late last year, which stopped things for a couple of weeks. I will have to wait until April to see if my results show anything interesting, weather permitting. Here's hoping!

In the meantime, here is another video of me collecting soil in Sherwood Forest.

More Ammonia

Here is the latest video in the Dirt Collector series. Here I am checking one of my ammonia posts to make sure that all is well. This particular one is on Clumber Park in Sherwood Forest.

Sampling and Sabotage

Nitrogen deposition comes in many forms. It can be diffuse, deposited in rain or from industry, or it can be more localised, from a single farm stocked with cattle or chickens for example. I have already investigated the former with bioassays and modelled nitrogen data. But the latter can be so localised, a matter of hundreds of meters, that it cannot be modelled. Therefore, it has to be measured in the field.

This localised nitrogen source usually comes in the form of ammonia and can be a significant input of nitrogen pollution to heathland, affecting vegetation composition and soil fertility. I can measure it relatively easily by placing a couple of ammonia samplers atop a 1.5 m wooden post. These samplers are capable of recording cumulative ammonia in the atmosphere for up to a month. So I can leave the samplers in the field, and replace them with new ones every month. To make sure that I include variation throughout the year, including manure spreading season for example, I record ammonia data for a 12 month period. Simple!

Or is it? Cows are curious things. They not only like to scratch up against conveniently placed posts (as do most livestock), but they also eat things readily, and quite happily munch on ammonia samplers!

Consequently, I had to make sure that my posts were out of the way of curious cattle. But there is another curious animal that is more difficult to avoid. People. Fingers stray into samplers, puncturing delicate membranes. Posts also go missing.

One post is even on a scout camp...not a safe place for anything! Little signs tell adults not to touch, but this doesn't work on kids. A sign saying "CHEMICALS! DO NOT TOUCH!!" however, seemed to do the trick.

The dataset will be complete by September 2011, sabotage notwithstanding. Let's hope there is a nice trend in there somewhere!

Not all goes as planned.

As I discussed in my last post, by June I had started to collect lichen samples in order to investigate their recovery in heathlands. This process is simple. You go to a heathland site with some pots, scissors and gloves. After eventually finding a patch of lichen, you carefully cut off a small sample and put it in a pot to take back to the lab.

Once the samples have been collected, I needed to isolate the fungal part of the lichen, grow it on an agar Petri dish, and then do DNA analyses on the resulting culture. Lichens are symbiotic organisms, made up of fungal and algal partners. If I was to try to get DNA from raw lichens, I would get a jumble of fungal and algal DNA. This is why I needed to isolate just the fungal partner from the lichen.

This is where numerous problems began. To isolate the fungus, I ground the lichen up in water, and then, using a microscope, I picked out fragments that appeared to have no algae cells. I then placed the fragments on agar.

Problem 1: The agar is designed to be a perfect place in which to grow fungus. This is fine when growing the fungus that I want, but not if other fungus spores get onto the agar. Unfortunately, lichens are covered with fungal spores. These grew very quickly once the fragements were on agar. Each time a fragment was contaminated with an invading fungus, I had to throw it away.

Problem 2: Algal cells are tiny. It takes just one cell on a lichen fragment in order for the algae to grow. After a couple of months, I could see green algae beginning to grow on some of my fragments. Therefore I looked at some of my "algae-free" fragments under a very high powered microscope. It soon became clear that most of my "algae-free" samples were not actually algae-free at all. Again, any contaminated fragments had to be thrown away.

It takes a long time to work on each lichen sample, so it took me just over three months to complete the work on all my samples. By this point the problems with algae and fungus contamination had caused me to loose a significant number of my samples. After spending time to investigate ways to counteract these problems, which were not successful, by October I had becided that it was best to cut my losses and give-up.

I hate giving-up, and do my best to make sure that I never have to give up on something. But sometimes science doesn't work. With the best of intentions, and all the time in the world, if something just cant be done then you just have to move onto something else.

I hope to come back to my lichen samples in the future. I have a number of different methods that I would like to try...I will just have to hope that these are more successful!

Next time I will talk about what I decided to do for the next chapter of my research.

Below are a couple of pictures of fragments that had been infected with algae and fungi.

The Thesis Begins

By May I was well into the second year of my project. The ultimate aims of a PhD are to produce new science, perhaps publish the data, and to produce a thesis for me to defend in a room full of experts at the end of the three years. The thesis will be a huge body of work, so it's best to start it earlier rather than later.

So May started off with a supervisory meeting to plan a month full of data analysis and thesis writing. By the beginning of June the methods and results sections for two thesis chapters (the soil and vegetation studies) had been drafted and approved. I also found time to write a manuscript for the Lundy Field Society Journal, summarising the work I did on the island.

As soon as that was finished I was straight into planning the next phase of the project. Lichens!!

Lichens are extremely sensitive to environmental pollution. We all know that pollution is a problem at the moment, but the sources of that pollution are changing all the time. Nitrogen pollution is becoming more problematic due to more intensive agriculture, but a reduction in fossil fuel usage, such as coal, means that sulphur pollution is much less of a problem than it used to be. Lichens are responding to this, and as a result some are expanding their ranges within heathlands.

I chose to investigate the reindeer lichen Cladonia portentosa. I will use DNA analysis to determine whether the expansion of this lichen is due to lichens coming into heathland patches from elsewhere, or because the lichen that is already present is simply spreading within the patch. So, firstly I need to collect some lichens from various heathlands around the East Midlands.

By mid-June this process had already begun. What I will actually do with the lichens will be discussed in part 3...

The varied life of a scientist

The end of my second year has passed, the third and final year of my PhD has begun. Time has flown by for two reasons: it's been extremely fun and rewarding, but also extremely busy. There is little time to take stock. My next few blog posts will summarise my experience as a scientist over the past six months.

Last time I updated my blog I was in the middle of a large block of lab work. By the end I was a little stressed and tired of the repetitive nature of the work. However, half way through March the perserverence payed off and I finally finished the work.

I was extremely eager to look at the data, and I was not disappointed. Interesting trends started to pop up and the exciting period of data analysis begun. Science is not done in the lab or the field, it's done in front of a computer. It's all about numbers and graphs. I can't wait to start telling people what I have found.

The rest of March was taken up with demonstrating lab techniqes to undergraduate students, finishing a few bits of fieldwork from earlier in the year, and a nice bit of data analysis.

Science would be useless if nobody has access to your work. So at the start of April I attended a conference in York to present my research to experts in the field. A daunting experience. However, the feedback was excellent and I managed to do some valuable networking to get my name known. I also got some really interesting pointers and ideas from other scientists about how my research could progress. A successful conference!!

Another bit of fieldwork followed later in April, just to collect data about the size of my study sites. Finally there was time enough for a week of holiday with my partner and parents, mixed with work of course. It just so happened that my parents live on the way to one of my sites in Cornwall, so I could travel down there to work on one of my sites while taking some time to relax at my parents.

So the work in March and April was varied, and certainly full. Part 2 documents two further months in the life of a scientist. Coming soon...

The lab work is nearly complete.

I have been extremely busy over the last few months. I am not a chemist, but this PhD required a good chunk of chemistry. It has been a huge learning curve for me.

All my experiments so far have told me how well the heather is growing in the soils that I collected from around the country, all with different nitrogen deposition values. These new experiments will tell me WHY the plants grew the way that they did by telling me how much nitrogen and phosphorus they took in during growth. Both these elements are essential in plant growth.

During December, I was in the lab virtually every day trying to learn the tecniques involved. Things didn't always go to plan. I would fill fifty tubes with all the chemicals, only to find out that the reactions didn't take place. I remade all the reagents, but it still didn't work. It took over a week, and a great deal of research, to find out that one of the dry chemicals isn't stable in solution. It could work for three weeks, and then suddenly stop working.

During January and February I have been putting my techniques into practice. Data collection begun on January 11th. All has gone to well so far, and I hope to be finished by next week. After these experiments are complete I will hopefully start writing my first paper, and start to write my final thesis.

In the meantime, these two videos explain what I have been doing for the last few months.

All 514 seedlings have been harvested.

It took a good week or so to separate all the seedlings from the soil, dry them in an oven to remove the water, and then to weigh them.

It looks like the initial results are OK; there is some relationship between plant size and nitrogen deposition. However, there are still a great many factors that need to be included in the analysis which could explain the differences in plant size.

These include the vegetation survey data, plant chemistry, the size of heathlands, management strategies, and many others.

Currently I am analysing the plants for nitrogen and phosphorus content, both of which indicate soil fertility.

A new video coming soon....