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2.1: Plant Habitats - Biology

2.1: Plant Habitats - Biology


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Learning Objectives

  • Identify plants used in all segments of horticulture.

The horticultural use of plants for decoration, food, medicine, and materials spans the history of human development on earth. While early European explorers to North America described the new world as untouched wilderness, generations of Indigenous residents used plants for decoration and ritual and managed growing conditions for food for thousands of years. The relationship between people, plants, and the environment on the Pacific coast of North America is described at this link to the Garry oak ecosystem [New Tab][1].

The early European plant explorer, Archibald Menzies has been credited as the first discoverer, describer, and collector of a number of plants whose provenance is the Pacific Northwest. Provenance refers to the populations of plants that occur naturally in local regions. For example, Pseudotsuga menziesii (Douglas fir) and Arbutus menziesii (Pacific madrone) both occur naturally in the Pacific Northwest. A plant’s nativity or provenance can be determined either geographically or politically. Acer saccharum (sugar maple), is native to central eastern North America, in other words, a Canadian native, but not a Pacific Northwest native. Similarly, Artemisia tridentata (big sagebrush) and Rhusglabra (smooth sumac) are native to interior British Columbia, but only to the dry interior valleys, not to the coast.

Native Plants

Plants that occur naturally in a place are considered native or indigenous to a place. Native plants have undergone genetic adaptations that have allowed them to evolve within the physical, chemical, and biological conditions of local ecosystems. As such, they function as part of a biodiverse community of organisms that includes plants, animals, and microorganisms adapted to local environmental conditions.

In North America, an indigenous designation is usually applied to plants that were present before first contact with Europeans. Thus, Plantago spp. (plantains), although widespread here, are not considered native since they were brought here as a result of immigration by early European settlers. However, the influences of climate change and globalization will likely redefine what it means to be indigenous.

Native gardening with indigenous plants that are appropriate to the conditions and geography of a given area can simulate the biodiversity of a natural habitat. Native plant gardens locally frequently include plants that are not native to the Lower Mainland of British Columbia, but also include plants native to other parts of the Pacific Northwest. For instance, Quercusgarryana (Garry oak), also discovered and described by Archibald Menzies, is now grown in gardens in the Lower Mainland, but is only found naturally in rain shadow climates, such as on southern Vancouver Island.

While not all native plants may be garden worthy for ornamental impact, those chosen from the regional locality of a garden will often blend appropriately and will be among the best adapted to local moisture, soil, and climatic conditions. Although native plants are not immune to pest and disease problems, the majority of locally native plants seem to attract fewer problems than many exotics do. Efforts to restore natural habitats using provenance-specific plants grown from locally sourced seed perform better than non-natives when established in these areas. However, changing climate patterns and the impacts of urbanization will likely have consequences for plant provenance.

Natural Habitats

Natural habitats provide the resources that enable indigenous plants to persist and thrive in existing growing conditions. Examples of natural habitats commonly used as horticultural garden themes include alpine, woodland, Mediterranean, and bog. The growth characteristics of plants native to these habitats have been shaped by differences in elevation, temperature range, precipitation, soil types and geology, and biological and chemical factors. Over time, indigenous species successfully adapted to the habitat conditions by developing specialized features for survival. Some features associated with alpine, woodland, Mediterranean, and bog plants are described below. Additional information about how evolution and natural habitats have influenced plant adaptations is available at this link to the Missouri Botanical Garden [New Tab][2].

Alpine plants

True alpine plants are well adapted to the harsh environments of high elevations. Above tree line, low temperatures, high sunlight, constant wind, dryness, and a short growing season are typical. Plant adaptations include growth low to the ground, a compact cushion or mat habit, and thick, waxy evergreen or pubescent (hairy), or curly leaves. Alpines, such as Campanula spp. (bell flower) flower in late spring and early summer and may have deep or extensive roots or below ground storage organs to persist in thin, low nutrient mountain soils. Although well adapted for extreme temperatures, alpine plants are typically intolerant of constant wetness around the roots and warm and humid summer conditions. Information about these specialized plants is available at this link to Adaptations to Alpine Plants [New Tab][3].

Woodland understory plants

The temperate woodland habitat is characterized by distinct growing seasons, a dormant period, relatively consistent precipitation, and rich soils. Trees dominate this habitat forming an overhead canopy that shades and cools the understory and forest floor to varying degrees. Woodland understory plants include layers of woody shrubs and herbaceous plants that are adapted in size, form, shade tolerance, and slow growth or dormancy when light and water are limited. Understory plants such as Hydrangea quercifolia (oakleaf hydrangea) flower in late winter to early summer, before the leaves of deciduous shade trees fully emerge. Depending on the amount of light available, some understory plants have distinctive leaf color and patterns of ornamental interest in gardens. Examples of understory plants for garden use are shown at this link to Creative Woodland Garden Ideas [New Tab][4].

Mediterranean plants

Mediterranean plants, such as Cotinus coggygria (smoke bush) and Lavandula spp. (lavender)are adapted to short, mild, and wet winters and long, warm, and dry summers. Some are short, dense, and shrubby evergreens that are suited to well drained soils, drought, and fire. Leaves may be leathery or reduced in size, and aromatic with thick, waxy or hairy coverings to reduce water loss, and bluish-grey (glaucous) or light in color to reflect excessive light. Some examples of naturally occurring vegetation are listed at this link to the Mediterranean climate Wikipedia [New Tab][5].

Bog plants

Bogs and freshwater habitats are typically oxygen and nutrient poor with acidic pH conditions. Quercus palustris (pin oak) is an example of a tree that naturally grows in these conditions. Bog plants are adapted to growing in standing water while marginal plants such as Irissiberica (Siberian iris) and Typha spp. (cattail) thrive in waterlogged soils and shallow waters with short term dryness. Some bog and marginal plants such as Juncus effusus ‘Spiralis’ have striking foliage and make good choices for planting areas with limited or poor drainage. Information about the bog habitat is available at this link to Plants of the Bog [New Tab][6].



Using an Outdoor Activity on Local Plant Biodiversity to Teach Conservation Ecology and Promote Environmentally Responsible Behaviors

McKenzie L. Doup Using an Outdoor Activity on Local Plant Biodiversity to Teach Conservation Ecology and Promote Environmentally Responsible Behaviors. The American Biology Teacher 1 May 2018 80 (5): 359–364. doi: https://doi.org/10.1525/abt.2018.80.5.359

Children today do not spend as much time outside as they did in previous generations consequently, they are not building connectedness to nature and are less likely to engage in pro-environmental behaviors. Environmental education is one way to ameliorate this problem. However, teachers are limited by their access to natural habitats, time, and field expertise. To address both of these issues, I present an inquiry-based activity for both Advanced Placement and general high school biology that requires students to spend time in nature, use authentic field methods for collecting data, and apply their findings to pertinent conservation issues. This four-day activity uses a simplified approach, called the meter stick random sampling method, to measure plant biodiversity of different local habitats. Time-efficient and not reliant on species identification, this method is designed so students can repeat this procedure in their backyards or at a local nature preserve. The data can be used to discuss how human disturbance of habitat affects biodiversity, the importance of biodiversity for the stability of ecosystems, and how to restore biodiversity locally.


What Is the Average Plant Biologist Salary?

According to same BLS survey data from 2015, the median salary for plant biologist was $82,150. The lowest 10% recorded a salary of $44,640 and the highest recorded a salary of $153,810. Despite employing amongst the fewest in numbers, management consultancy and technical services paid the highest salaries with an average of $105,430. Research and development paid the second highest and still above the median at $87,650. Third was pharmaceutical employment and lower than the median at $77,960. Chemical manufacturing was fourth at $74,840. Much lower than the other pay bands was education with an average salary of $55,560.


Minimum Academic Requirements

The Faculty of Graduate and Postdoctoral Studies establishes the minimum admission requirements common to all applicants, usually a minimum overall average in the B+ range (76% at UBC). The graduate program that you are applying to may have additional requirements. Please review the specific requirements for applicants with credentials from institutions in:

Each program may set higher academic minimum requirements. Please review the program website carefully to understand the program requirements. Meeting the minimum requirements does not guarantee admission as it is a competitive process.

English Language Test

Applicants from a university outside Canada in which English is not the primary language of instruction must provide results of an English language proficiency examination as part of their application. Tests must have been taken within the last 24 months at the time of submission of your application.

Minimum requirements for the two most common English language proficiency tests to apply to this program are listed below:

TOEFL: Test of English as a Foreign Language - internet-based

Overall score requirement: 90

IELTS: International English Language Testing System

Overall score requirement: 6.5

Other Test Scores

Some programs require additional test scores such as the Graduate Record Examination (GRE) or the Graduate Management Test (GMAT). The requirements for this program are:

Prior degree, course and other requirements

Prior Degree Requirements

Students admitted to the Ph.D. degree program normally possess a M.Sc. degree in plant science or a related area, with clear evidence of research ability, and a strive for research excellence. Transfer from the M.Sc. to the Ph.D. program is permitted under Faculty of Graduate and Postdoctoral Studies regulations.


2 METHODS

2.1 Study sites

Sampling was conducted in three small (first or second order) urban gravel-bed rivers in Leicestershire and Nottinghamshire, U.K.: the River Leen, Black Brook, and Saffron Brook (Figure 1). Each river was sampled over two consecutive days in September and October 2018. Straightened reaches with homogenous substrate grain-size and morphology were selected to minimise any effect of natural morphological heterogeneity. Sites were similar in dimension, water quality, and discharge, but differed in urbanisation intensity (Table S1).

The predominant natural substrate (substrate is defined here as riverbed material on which an organism lives) at all sites was gravel and cobbles (hereafter rocks), with some interstitial fine sediment (sand and silt). Rocks were comparable in size to anthropogenic litter pieces and could be easily isolated from the riverbed to collect the macroinvertebrates inhabiting them (similar to anthropogenic litter). Hence rocks were chosen for comparison with anthropogenic litter. Both rocks and anthropogenic litter were sampled from the riverbed surface for consistency. There was not any discernible structure to the bed sediments, such as armouring, as subsurface sediments were visually similar to those on the surface.

2.2 Field methods

Anthropogenic litter density was assessed at each site by measuring the area of riverbed (average channel width × river length surveyed) containing 100 pieces of anthropogenic litter. Rock and anthropogenic litter samples were collected from the full width of the channel and the surface layer of the riverbed. Whilst moving upstream in a grid pattern, we collected alternately encountered anthropogenic litter items (providing 50 samples at each site), and a representative sub-sample of 50 rocks by pacing through the sampling area and taking the rock immediately at the sampler's foot (Wolman, 1954 ). Only items larger than 1 cm in their b-axis length were sampled, as smaller items were difficult to consistently collect and macroinvertebrate numbers would be low on such items. Items were described in terms of their material composition (fabric, glass, metal, plastic, masonry, rock, or other). Pieces of masonry (e.g. brick, concrete, and roofing tiles) were classified as rocks in comparisons of all anthropogenic litter types against all rocks, as it was thought that they may function like natural mineral substrates. However, masonry and rock samples were considered as separate materials in analyses of material types to test this assumption.

Macroinvertebrates were collected by transferring items (anthropogenic litter or rocks) from the riverbed into a 1-mm mesh kicknet held directly downstream (following Benke and Wallace’s [ 2003 ] methodology for sampling macroinvertebrates on large wood). The contents of the net were placed into a sampling bag, along with the item, and preserved with industrial methylated spirit. Large or embedded items were cleaned of macroinvertebrates in the field by scrubbing a set area of 0.03 or 0.06 m 2 depending on their exposed area (0.03 m 2 was roughly equivalent to the median surface area of anthropogenic litter pieces) with a brush to dislodge macroinvertebrates into a kicknet held downstream (Pilotto et al., 2016 ).

2.3 Laboratory methods

All anthropogenic litter and rock items were individually washed through a 500-µm mesh sieve, then manually processed to collect macroinvertebrates. Macroinvertebrates were identified to species or genus level where possible. Exceptions were Diptera and Sphaeriidae, which were identified to family, Oligochaeta to subclass, and Acarina to order. Taxonomic levels were consistent between samples and sites. Identification followed Holland ( 1972 ), Ellis ( 1978 ), Friday ( 1988 ), Wallace et al. ( 1990 ), Edington and Hildrew ( 1995 ), Reynoldson and Young ( 2000 ), Killeen et al. ( 2004 ), Elliott and Humpesch ( 2010 ), Cham ( 2012 ), Dobson et al. ( 2012 ), and Elliott and Dobson ( 2015 ). Trichoptera (caddisfly) pupae, unlike larvae, could only be identified to family level so were excluded from further analysis. The data analyses outlined in Section 2.4 were repeated with family level data, which included caddisfly pupae, and findings were qualitatively identical (Table S2).

The surface area of each item (anthropogenic litter or rock) was approximated by wrapping the item in tin foil and weighing the resultant foil pieces (1 g: 0.0214 m 2 Dudley et al., 2001 ). The surface area of flexible materials or items with complex shapes (e.g. plastic bags) was determined using equations for the surface area of the approximate geometric shape (Bergey & Getty, 2006 ). Items that were too large or embedded to be collected from the field were measured in situ.

2.4 Data analysis

All statistical analysis was conducted using R statistical software (version 3.6.3 R Core Team, 2020 ). Completeness of sampling was assessed by calculating coverage for anthropogenic litter and rocks at each site. This measure of sample completeness estimates the proportion of total individuals in a community that belong to taxa in the sampled community (Chao & Jost, 2012 ). Macroinvertebrate density was calculated by dividing the total macroinvertebrate abundance across taxa by the sampled surface area of an item (0.03 or 0.06 m 2 for partially sampled items). Macroinvertebrate diversity was assessed by calculating Hill's numbers in vegan (Oksanen et al., 2019 ). The Hill series are defined to the order q (D q ), which determines the weighting of rare to abundant taxa for each index. D 0 is equivalent to observed taxa richness, which places greater emphasis on rare taxa as it is insensitive to relative frequencies (i.e. evenness) D 1 is equivalent to the exponential of Shannon's entropy, which is weighted towards common taxa and D 2 to the inverse of Simpson's diversity, which is weighted towards highly abundant taxa (Tuomisto, 2010 ). Each point in the series therefore provides complementary information on taxa richness and evenness.

The mean surface area of rocks (including masonry) was four times smaller than that of anthropogenic litter items (rocks: 0.03 m 2 ± 0.01 [SE], anthropogenic litter: 0.12 m 2 ± 0.02 two-sample Wilcoxon W = 16,899, p < 0.001). Given that a strong positive relationship exists between item surface area and total macroinvertebrate abundance (Spearman's rank [Rs] = 0.80, p < 0.001), as well as between surface area and observed taxa richness (D 0 Rs = 0.79, p < 0.001), all subsequent analysis controlled for surface area (by including area in linear mixed effect models and generalised linear models) to account for this difference between substrates.

To test for differences in density and diversity (D 0 , D 1 , and D 2 ) between anthropogenic litter and rocks, linear mixed effects analysis was performed using lme4 (Bates et al., 2015 ) with significance calculated for parameter estimates using lmerTest (Kuznetsova et al., 2017 ). To compare diversity, substrate (anthropogenic litter or rock) and sampled surface area were entered as fixed effects, and site (River Leen, Black Brook, or Saffron Brook) included as a random effect. Linear mixed effects models for density excluded surface area, as this factor is already incorporated into the calculation of density for each item, but otherwise model structure was identical. Model validation and checking followed the protocol in Zuur et al. ( 2009 ). Significance values for the effect of substrate type were identified by likelihood ratio tests (distributed as χ 2 ) of the full model against a null model without the substrate factor. Linear mixed effects analyses were repeated, substituting the substrate factor for material composition using a single factor with seven levels: fabric, glass, metal, masonry, plastic, rock, and other. Significant differences between material types were examined using parameter estimates and associated p values calculated using Satterthwaite approximation in lmerTest. Thus, we looked for differences between substrates (anthropogenic litter and rock), and between material types (fabric, glass, metal, masonry, plastic, rock, or other) in separate analyses.

Macroinvertebrate community composition was compared using the manyglm function in mvabund (Wang et al., 2020 ). The function fits generalised linear models (GLMs) to the raw counts for each taxa assuming a negative binomial distribution, with substrate type, sampled surface area, and site as explanatory variables without interactions. A sum-of-LR test statistic was obtained with significance assigned using randomisation (999 permutations), where the p value is adjusted for multiple testing using step-down resampling. This approach deliberately specifies a mean–variance relationship, inherent to count data, meaning that it can address the problems of confounded location and dispersion effects and difficulty detecting effects expressed in low-variance taxa, common to distance-based community analysis such as SIMPER and PERMANOVA (Warton et al., 2012 ). Manyglm tests were also repeated substituting substrate for material composition.

Differences between communities were visualised using boral (Hui, 2020 ) a model-based approach to unconstrained ordination that fits a latent variable model to raw abundance data and can be interpreted in a similar way to non-metric multidimensional scaling ordination (Hui, 2015 ). Ordination assumed a negative binomial distribution, and sample identity effects were included so ordination is based on composition rather than relative abundance. Site was included as a fixed effect. Ordination was repeated for individual sites to visualise differences between material types within each site.


A Brief History of Plant Habitats in Space

It’s fairly common knowledge: where you grow a plant makes all the difference. Botanists, gardeners, and farmers alike have worked for thousands of years to perfect plant growth in any environment. From the fields of the Midwestern United States to the arid climate of the Middle East, humans will grow plants wherever they’re needed. And as technology has only gotten better and better, its ushered in a new era of “we can grow plants anywhere” . Timed lighting and watering systems have made indoor gardening a real option for urban environments. Vertical gardening is being discussed to remedy spacing issues. Hydroponics is becoming ever more popular. These are the solutions being created to address the challenge of -growing plants anywhere we damn well please- and solidifying our status as the true masters of plant science. But, for an even greater challenge, we look no further than our solar system. The real question is: can we grow plants in space? What tools will be used to grow our plants in space?

These are the questions that are essential for astrobotany (the study of plants in space) research. They are the questions that academic botanists ask themselves daily, and they are questions that may have crossed your mind as well. While astrobotany is generally considered to be a younger discipline, its history is richer than one might expect. For as long as we’ve had dreams of space travel, we’ve recognized the need for our plants. And as long as we’ve tried to grow plants in space, we’ve needed a place to grow them.

Here is a brief history of plant habitats in space.

1946 – Inside V-2 Rockets

Using the term very loosely, the first “space plant habitat” could technically be considered V-2 rockets. No actual plant growth occurred in 1946, when NASA launched maize seeds on repurposed V-2 rockets, but this is the first time plant material was ever subject to spaceflight. A true plant habitat? Maybe not so much. The first attempt at spaceflight plant biology? Yes, very much so.

1973 – “Unnamed Plant Growth Compartment” on Skylab

One of the oldest spaceflight plant biology experiments was a student project and joint collaboration with NASA. A true feat of engineering, and one of the oldest space stations, “Skylab” was a modified Saturn V rocket in which early spaceflight research was performed. Among them, the growth of rice in their plant growth chamber. Here is a description of the chamber from NASA experiment archives.

“The growth container for this experiment consisted of eight compartments arranged in two parallel rows of four. The growth container was similar to cardboard potting cartridges found at plant nurseries. Each compartment had two windowed surfaces, which allowed periodic photography of the developing seedlings from both a front and side view. The study of light intensities on plants was accomplished by using light filters. For this purpose, five windows were covered with special filters with different degrees of light transmittance, two windows were blocked to prevent any light from reaching the seeds, and the remaining window had no filter, allowing 100 percent transmission of light. Three rice seeds were inserted into each compartment through covered holes. Twenty-four seeds were inserted into a nutrient agar medium with the aid of an automatic seed planter. Photographs were taken at regular intervals for 30 days.” – Plant Growth/Plant Phototropism (ED61_62)

This pioneering experiment addressed one of the major variables that influence plant growth: lighting. As early as 1973, plant space habitats already included light filters, nutrient agar, and an automatic seed planter.

1971 – Oasis Series Growth Chambers

The Soviet Oasis series marked the first biological life support flight experiments, flying from 1971 to 1986. These Oasis chambers were beneficial to astronauts’ mental health, with British astronaut Mike Foale commenting on how encouraging it was to see his seedlings sprout. One cosmonaut even placed his sleeping bag next to an Oasis, so he could check plant growth as soon as he awoke. Cosmonaut Yuri Artyukhin described how the Oasis was the brightest place on the station, so crew members spent considerable time near it. There were four iterations of Oasis.

1973 – Vazon

In 1979, cosmonauts received a very special gift: a Vazon growth chamber with a kalanchoe plant inside. They were so pleased with this plant that they named it “life tree”. Although it was used for a variety of plant species, the Vazon was initially designed to grow bulbous plants in space, like onions and tulips. The Vazon first flew to the Salyut 6 in 1973, and continued to support plant research on Salyut 7 and the Mir space station. Although the Vazon was a successor to the Oasis series growth chambers, it was simpler in many ways. It had no lighting system or environmental controls, and instead relied on light and air from the space station cabin. Learn more here!

1973 – Malachite

Orchid flowers can seem otherworldly, but did you know that the Soviet Space Program once sent blooming orchids into orbit?! Epidendrum orchids were cultivated in Malachite, a small growth chamber flown on Salyut 6 for 110 days. This 1973 orchid experiment was designed to investigate the psychological comfort that cosmonauts felt when interacting with the plants. The orchids were launched in bloom, but unfortunately the flowers immediately fell off the stems. These orchids produced no additional flowers in orbit, so no seeds resulted from this experiment. At that time Malachite was one of the largest plant growth chambers ever sent to space, and although its orchid experiment was largely unsuccessful, it paved the way for even larger growth chambers that were yet to come. Learn more here!

1982 – Svetoblok

Svetoblok was the first airtight, sterile growth chamber for spaceflight, and its experiments helped us understand that plants can develop flowers in space. This chamber was compact, with a small removable cylinder that could be returned to Earth independently from the chamber. To return the plants to Earth, cosmonauts simply held the removable cylinder in their laps on the trip down! Svetoblok was first flown in 1982, and was used on both the Salyut and the Mir space stations. Svetoblok’s sterile environment was believed to be a big reason for its success. In 1982 cosmonauts successfully grew the first flowers in space from Arabidopsis, a tiny mustard species used commonly in research. Although these flowers bloomed and began to develop fruit the male and female organs degenerated, so no viable seeds were produced. The success of flowering in Svetoblok demonstrated that the seed-to-seed life cycle should be possible in microgravity, given the right environmental conditions. Svetoblok was one of the key growth chambers that laid the groundwork for plant reproduction in space. Learn more here!

1982 – Phyton/Fiton on Салют-7 (Salyut 7)

Phyton (occasionally called Fiton) was designed to support seed-to-seed experiments, with the intention of demonstrating that plants can reproduce normally in space. Phyton was successful: it produced the first space-grown seeds, achieving what we call ontogenesis (seed-to-seed growth) with Arabidopsis. It grew plants inside glass cylinders with nutrient agar, had a powerful lamp, and used an air filter to remove air contaminants. It even included an automatic apparatus that could plant seeds in orbit! Python was also highly adaptable: scientists could adjust individual cylinders, so they could test different light treatments, water quantities, plant species, and nutrient solutions. Phyton was developed by the Ukrainian Institute of Molecular Biology, and ran flight experiments on Salyut 6 and Salyut 7. There were three iterations of Phyton.

The literature also states that there was a centrifuge aboard Salyut 7. Lettuce was examined under 0.01, 0.1 and 1 g conditions using this equipment.

* Quick searches of Soviet era space equipment often yield few results. This could be a consequence of strict science rules imposed upon Russian scientists to prevent American technology theft during the Cold War. During this time, many researchers were forbidden to release detailed papers about their experiments.

1982 – Plant Growth Unit (PGU)

For 15 years, the Plant Growth Unit (PGU) was a highly successful platform for shuttle-era astrobotany experiments (1982-97). The PGU was the first American platform to run regular flight experiments on biological life support systems, and its experiments examined seedling growth, lignification, and reproduction. The PGU was designed and built by Lockheed Missiles and Space Company for the Ames Research Center, and was eventually upgraded into its successor, the Plant Growth Facility (PGF). Learn more here!

1990 – “SVET” on Мир (Mir)

The plant habitat SVET (Russian: light) was installed in 1990 aboard the spacecraft Mir. SVET was located in the Kristall module of Mir and consisted of 4 basic units:

  • the plant growth chamber itself
  • the root module
  • the light and control unit
  • the GEMS (Gas Exchange Measurement System)

Plant varieties such as dwarf wheat and Brassica rapa were grown in SVET, with important variables being controlled and measured using these equipment. Substrate moisture was one of those being studied.

1997 – Plant Growth Facility (PGF)

For years, the Plant Growth Unit (PGU) was the best plant growth chamber for studying tiny plants in space. Yet, scientists and engineers found numerous ways to upgrade the PGU, enhancing many pieces of equipment while maintaining the same dimensions, and they called this upgraded version the Plant Growth Facility (PGF). This system had a much higher-output lighting system, could accommodate experiment-specific growth media, and was capable of controlling humidity, temperature, and CO2 concentration. Like the PGU, the PGF was a platform for plant reproduction experiments, and it helped demonstrate how ventilation and extra CO2 are needed for seeds to develop normally in space. In 1997 the PGF flew on the shuttle for 15 days to test the effects of microgravity on plant growth for the Collaborative Ukraine Experiment (CUE). Learn more here!

2002 – Biomass Production Chamber (BPS)

The Biomass Production System (BPS) was developed by Orbital Technologies Corporation in partnership with NASA engineers and scientists. It was initially designed for the Shuttle and SpaceHab, but was later modified to fit in the International Space Station (ISS), and it contained two experiments on the ISS in 2002 during expedition 4. The first experiment was a Technology Validation Test (TVT), where the BPS validated several subsystems and technologies that were later used to design the Plant Research Unit (PRU). The second experiment was called Photosynthesis Experiment and System Testing and Operation (PESTO). The PESTO demonstrated that plant productivity (photosynthetic rate, transpiration rate, and biomass) does not differ from ground controls. From this experiment, scientists learned that gas exchange is not directly affected by microgravity, but is affected indirectly by the lack of gravity-driven convection in microgravity. Learn more here!

2002 – Lada Plant Growth System

Lada, named for the Slavic Goddess of Fertility, is the oldest greenhouse system on the International Space Station. Lada is a traditional spaceflight plant habitat with two different growth compartments for growth comparison. It design and technology are modeled after its predecessor “SVET” on Mir.

“Lada consists of four major components (a control module, two vegetation modules and a water tank) and is designed to be deployed on a cabin wall. This deployment scheme was chosen to provide the crew therapeutic viewing and easy access to the plants. The two independently controlled vegetation modules allow comparisons between two vegetation or substrate treatments. The vegetation modules consist of three sub-modules, a light bank, the leaf chamber, and a root module.”
Lada: The ISS Plant Substrate Microgravity Testbed [accessed May 27 2018]

2002- Plant Generic Bioprocessing Apparatus (PGBA)

The Plant Generic Bioprocessing Apparatus (PGBA) was a plant growth habitat on the International Space Station. Plants grown on the PGBA include Arabidopsis thaliana, wheat, tomatoes, loblolly pine, spinach, periwinkle, white clover, pepper, sage, and purple cone flower.

2006 – European Modular Cultivation System (EMCS)

The European Modular Cultivation System (EMCS) was built for plant research, but could also hold experiments on small animals (insects and small invertebrates). It was funded by the European Space Agency (ESA), and was developed by an industrial team led by the German company EADS-ST Friedrichshafen. Specialists at NASA’s Ames Research Center optimized it for certain experiments by developing experiment-unique hardware. It was installed on the ISS in the US Destiny module (2006-08), and the European Columbus module (2008). The EMCS hosted a wide variety of plant experiments that helped scientists understand imaging systems, plant movement, plant membrane proteomes, plant growth and development, cell-wall genetics, and plant tropisms in space. Learn more here!

2009 -Plant Experimental Unit (PEU)

The Japanese Plant Experimental Unit (PEU) was designed for the Space Seed experiment, to test the seed-to-seed life cycle of Arabidopsis in microgravity. Eight units were launched to the ISS in 2009, and were mounted in the Cell Biology Experiment Facility (CBEF) inside the Kibo laboratory for 62 days. Arabidopsis is a very small plant, so each PEU was also quite small: the growth area of one PEU was only 4.8 cm tall, 5.6 cm wide, and 4.6 cm deep. Learn more here!

2011 – SIMBOX

The Science in Microgravity Box (SIMBOX) is scientific hardware developed by DLR (German Aerospace) in cooperation with CMSEO (China Manned Space Engineering Office). SIMBOX was flown on a Shenzhou 8 mission in 2011 and contained biological experiments including a study on Arabidopsis with 1g centrifugal control for Arabidopsis in SIMBOX (onboard Shenzhou). SIMBOX has an RNAlater injection system, lights, temperature control and a centrifuge.

2014 – “VEGGIE” on the International Space Station

The VEGGIE vegetable production unit was developed by Sierra Nevada subsidiary ORBITEC and installed on the ISS in 2014. There are currently two VEGGIE modules on the ISS. Plants are grown with root mats and ‘plant pillows’, which are small, wicked pillows that contained calcined clay and fertilizer for the plants to grow in. The lights on VEGGIE are primarily red and blue light, which are LEDS optimized for plant growth, because they have the highest energy wavelengths. Air flow and pressure are also controlled in each of the VEGGIE systems. Below, NASA describes the process of beginning a plant experiment in the growth compartment.

“Wearing sunglasses, Swanson activated the red, blue and green LED lights inside Veggie on May 8. A root mat and six plant “pillows,” each containing ‘Outredgeous’ red romaine lettuce seeds, were inserted into the chamber. The pillows received about 100 milliliters of water each to initiate plant growth. The clear, pleated bellows surrounding Veggie were expanded and attached to the top of the unit.”NASA KSC 05/16/14

Summary

The timeline of plant habitats for space has ebbed and flowed with the construction and maintenance of space stations, research vessels, and spacecraft. Plant biologists involved with these projects have largely (and rightly) stuck to their wheelhouse. The control over as many variables as possible is key in the development of these plant habitats. This is a common thread amongst all the discussed equipment above. Air flow, pressure, watering, nutrients, and light are all closely controlled and monitored. In addition to this, sterilization from start to finish as a plant goes through its life cycle is essential. Contamination could jeopardize important data. These are concepts realized and practiced as early as the 70s and they are still continued to this day.

This overview of important plant habitats left out hardware such as BRIC (Biological Research In Canisters) and SIMBOX, as those are less “greenhouse”, but more petri-dish, or biological organism related. These smaller research tools have less specificity when it comes to growing plants, but yield equally important data when it comes to astrobotany research.

There is still much to learn when it comes to our endeavors in space agriculture. Despite a history spanning nearly six decades, the world’s space programs still have yet to produce the first bioregenerative life support system. As our rocket technology advances, our biological sciences must keep up. We must push for the development of more and more advanced plant habitats. To further our space legacy, we will continue to learn, continue to build, and continue to grow plants in space.


Watch the video: 1. Classification of plants based on habitats (November 2022).