May 28, 2020

Did fill kill a large American linden in Washington Square Park?

American linden, Washington Square Park

The title of this post is a rhetorical question. While I cannot say definitely that fill killed the 35-inch American linden in the northwest woodland of Washington Square Park, fill contributed to the death of this tree. In summer 2019, the soil grade in the northwest woodland was changed (fill was added) as part of a lawn repair project. I voiced concerns about the impact of soil mounding on mature trees on this blog and directly with the NYC Parks administrator of the park.

The critical root zone (CRZ) of a tree is just that: it is essential to the health of a tree and every effort should be made to prevent disturbance in this area. A quick estimate of the CRZ is the area below a tree's drip line or the area underneath the tree's canopy spread. NYC Parks requires a CRZ ratio of "½ foot per one inch DBH (diameter at breast height) to 1½ foot per one inch DBH." The agency provides a stricter calculation of 1½ foot per one inch DBH standard if a species fill tolerance is unknown. It is known that lindens have a low tolerance for grade change so I would argue that the higher standard should be used. The American linden in the northwest woodland is 35 inches in diameter. Even using the lowest ratio of 1/2 foot per 1 inch DBH, disturbance should not have occurred within 17 feet of the trunk of the linden. Fill was added with the CRZ of the linden tree.

Photographic evidence shows a dramatic change in the canopy health of the large American linden in the northwest woodland. The tree has not leafed out as of the writing of this post. Photographs taken in previous seasons show the tree in leaf. 

JULY 2017 via Google Maps user

AUGUST 2019 via

American linden, Washington Square Park

MAY 15,2020 via

It is unfortunate to lose another large tree from the canopy in Washington Square Park. In June 2019, I reported on the removal of 10 large trees from the park between 2017 and 2019. The linden had several dead limbs, but the branches were relatively small and did not have a pattern which might indicate an existing abiotic or biotic stressor. If the linden was stressed prior to the grade change, the layering of fill above its critical root zone would have intensified the stress and reduced the tree's coping ability and gas and water exchange. Arboricultural standards are evidence based and are recommended to protect trees, especially vulnerable species and mature trees. The loss of a mature tree is significant; its size related to its age has conferred numerous benefits both quantified and unnamed to its biophysical and cultural environments. The preservation of existing canopy on public land seems like an easy task, the proverbial low-hanging fruit. The case of this dead linden in a celebrate public park shows that my assumption is naive. There is much work to be done to preserve our existing urban tree canopy.

April 3, 2020

Observe nature from home

It’s spring! Migratory birds are on the move and plants are flowering and leafing out. Typically, our public landscapes would be teeming with people, some of whom would be outside to count brightly colored warblers, to watch cherry trees reach peak bloom, and to track the “green wave” of maples, oaks, and poplars pushing out new leaves. In the global wake of Covid-19, however, human movement is largely on pause. In the U.S., several states have orders and advisories to stay home. Despite this incredibly necessary limitation, if you have a room with a view (or a private outdoor space), you can make nature observations from home.

binoculars and field guides

Observation tools

Observing nature while inside might require binoculars depending on how close birds or plants are to your windows. If you have bird feeders next to your windows or in your private outdoor space, you will be able to bird watch without binoculars. If you have neither, and birds will congregate at some distance beyond your windows, then binoculars or telephoto lenses will be essential. The same is true if you want count a tree’s leaves or see the details of its flowers.

Nature watch station

Once you’ve decided on your observation tool, set up your nature watching station. Find the window in your home that offers the best views of sky and nearby habitats—vegetation and/or water. Stock your observation deck with binoculars and field guides. Other tools to consider are a camera and art materials, in case birds or other animals linger.

Share your nature finds

While some birders and botanizers have dedicated places in which they track nature through the seasons, some bird and plant watchers like to go to the latest super bloom or bird fallout sites. Since human travel is restricted now, it’s unlikely that people will be trekking locally or regionally to catch these natural phenomenon. However, from your indoor perch, you might be witness to flowers and birds that are of high interest to other nature observers. Furthermore, seasonal data about bird and plant activity are still important to scientists and land managers. Share what you are seeing. Upload your plant photographs to iNaturalist. List your bird sightings with eBird. Use SciStarter to find other community science projects.

Think beyond listing, though. For those of us whose rooms don’t have the best views of the diversity of birds that will move through North America or of the blooms and expanding green canopies, stream what you are seeing on Instagram or YouTube. Publish your photos and stories on a blog or in a Twitter thread.

Virtual nature encounters

If your living situation precludes direct nature observation, online nature cameras can deliver nature’s wonders to you. Universities on both coasts host raptor cams. The Campanile Tower at the University of California, Berkeley is home to a pair of peregrine falcons. The Cornell Lab of Ornithology hosts a bonanza of bird cams, 15 in total. If forest canopies are more your thing, watch a New England forest leaf out courtesy of the Harvard Forest Phenocam. The mother lode of live nature cams is hosted by lode To see, and even to help identify, what people are seeing worldwide, head to the Explore section of iNaturalist.

Let’s join in the study of seasonal activity in plants, birds, and other animals, known as phenology. It’s another way to connect to each other and to nature during this time of physical distancing.

March 24, 2020

Birding for beginners

Image: Screenshot of (Cardinal photo by Bruce Jastrow/Unsplash)

A spot of good news: I've got a new story--a how to guide for beginning birders! It was published by Popular Science as How to start birding in any U.S. city. Thanks to DIY editors John Kennedy and Sandra Gutierrez. Let me know what you think about the bird watching guide. Be well.

March 3, 2020

Kindergarten Tree Walk

Not only is leaf litter an important resource for forest function, fallen leaves can also spark environmental learning experiences. One day, a kindergarten-aged boy was walking through Washington Square Park and saw a large leaf on the ground. He collected the leaf to bring to his kindergarten teacher. His class was studying trees. The teacher and the students identified the leaf as an oak but did not know if the lead belonged to a pin oak or a red oak. (Note: a pin oak is in the red oak group.) The teacher reached out to me because of my connection to the park. We agreed on a tree walk with a classroom tree lesson and an outdoor identification session. I visited with the class twice; I worked with one half of the class, about 10 students, on each visit.

I started off each visit asking the children to describe a tree. Their answers reminded me of the story of the blind men and the elephant. No child offered a complete definition, but the list of features they generated was comprehensive. On one of the days, the teacher had a debrief session and noted additional student observations on the board. All of the student responses where interesting but I particularly appreciated the following description: “big piece of wood standing up where animals can live.”

Our tree walk occurred on the south side of the block on which the school sits. I had walked both sides of the block before meeting with the students so was familiar with the species and the seasonal changes each tree was undergoing. I paired trees and compared and contrasted the species along the block to teach and illustrate basic tree identification. We talked about leaf arrangement (opposite versus alternate), flowers (showy versus inconspicuous), fruit, bark patterns, and new twig growth. The most appealing trees had showy flowers (the Callery pears on the street and the Kwanzan cherries in the small front yards). The students were also fascinated by the herbaceous plants in the tree beds, most of which were growing spontaneously, as well as the trash on the soil.

I would like to replicate this workshop for other early childhood education programs. The students were engaged indoors and outside, and the head teacher provided positive feedback. The tree walk was a valuable experience for me as I grow my outdoor educator skills.

Photos courtesy of the classroom teacher.

February 20, 2020

Family Field Trip - Pelham Bay Park

For our second family field trip of 2020, we visited Pelham Bay Park in the Bronx. Our original itinerary was to spend time on Orchard Beach and to go to nearby City Island. We came for the beach and discovered woods and islands.

Related Link - Family Field Trip - Shirley Chisholm State Park

The sand at Orchard Beach is wide and deep. We collected shells, watched the gentle waves, and marveled at the calm gulls. After getting chilled on the beach, we went to City Island to warm up with food and drink. We thought we would be able to get down to the water on City Island but we did not find a way to do so. We returned to Ocean Beach to explore the woods we saw on the other side of the vast parking lot. The amount of space devoted to black top is shocking and seems wasteful, but my husband pointed out to me that it must be heavily used during beach season. Over the course of our day at Pelham Bay, we noticed many people using the parking lot in many different ways: boxing arena, kite flying, drag racing, and driving lessons. The gulls also rested on the parking lot.

Our woodland walk kicked off  on Hunter Island, a 166-ac peninsula, and former island. I blissed out on all the trees, though the stretch of canopy we walked under was not the old growth that the park is known for. The leaf litter was composed mostly of oaks. We saw a stand of pines early on, and fungi, too.

On Hunter Island we felt isolated from the bustling city, though the park is in a flight path. We heard and saw lots of airplanes. We saw four people while walking at a very slow pace, and our paths only briefly overlapped.

At a fork in the trail, we turned downhill observing more fungi and a spinney of spruce as we went.

The trail brought us alongside the shore where we saw geese, ducks, gulls, and other islands. We crossed a dilapidated causeway, walked on a marshy beach (aka Twin Island, an island at high tide only), and clambered up and around Two Tree Island. The view from Two Tree Island was spectacular! After the kiddos interacted with the various shells and pools of water, we descended Two Tree Island. We walked back across Twin Island, but instead of taking the causeway, we took the trail to Orchard Beach.

I highly recommend visiting Pelham Bay Park! There's more to discover than I shared here.

Sources further reading:
(1) Hunter Island (Bronx) - Wikipedia
(2) Bronx Islands: A Brief Guide - Welcome 2 The Bronx

January 28, 2020

Family Field Trip - Shirley Chisholm State Park

Last Sunday, my family and I visited Shirley Chisholm State Park in Brooklyn, NY. I've been wanting to visit this park since before it opened because...Shirley Chisholm: so many firsts as a Black woman politician. Read Chisholm's bio at the National Women's History Museum.

Before visiting the state park, I didn't know much beyond the park's namesake. Once there, we picked up a map which showed trails and provided the park's history. Formerly the Pennsylvania and Fountain landfills, which were decommissioned in 1983, the land is now a 407-acre public park! Approximately 1.2 million cubic yards of clean soil at a depth of four feet was used to cap the former landfills. The park peaks at 130 feet above sea level. The landscape is a mosaic of three ecosystems: coastal meadows, wetlands, and woodlands. The agencies involved in the landfill conversion to parkland are the City of New York, the National Park Service, and New York State Parks.

As soon as we picked up our map, I strapped on my binoculars, and opened the eBird and iNaturalist apps on my phone. My kiddos led the way. I stopped often to list birds and to photograph plants. I got some grousing about my stop-and-go pace.

We walked to Penn Pier where we ate a snack, and watched gulls and ducks. Gull and duck ID are not my strong suit but I still enjoyed watching these birds.

From Penn Pier, we walked along Hendrix Creek Road towards the Pennsylvania Entrance. On this leg, the children were the ones who dawdled! They stopped to collect worms, pill bugs, soil, and dew-covered grass. My daughter has been keeping a bug catcher in her coat. We saw a mockingbird, a Northern flicker, and 2 red-tails on this trail.

Unfortunately, we didn't know that the larger section of the park, on the other side of Hendrix Creek, was open. We would have loved to extend this family field trip. There will be more to explore on future visits to New York City's newest state park.

Tell me about your family field trips in the comments.

January 16, 2020

Eating Ginkgo biloba seeds

Ginkgo biloba is one of my favorite trees. The bi-lobed, fan shape leaves are pretty, its winter silhouette and straight bole are striking, and its has a very ancient pedigree. I have written about the ginkgo "fruit", ginkgo in art and culture, and a brief natural history of the ginkgo. In each of these previous posts, I have mentioned the Ginkgo biloba "fruit." The Ginkgo biloba "fruit" is not a botanical fruit. Ginkgo biloba is a gymnosperm meaning it has naked seeds. The tree's seeds are not enclosed in an ovary. (The fruits we eat are ripe ovaries, FYI.) The botanical term for the flesh that covers the ginkgo seed is sarcotesta. When this flesh is crushed underfoot, it releases an off-putting odor. The flesh can also irritate human skin.

Until last fall, I had not ginkgo seeds. My first experience eating ginkgo seeds was at a C.U.R.B. banquet held on Governor's Island in October 2019. The seeds were chewy and tasted nutty, similar in flavor to a pistachio. Yum! I vowed then to harvest fallen seeds and cook them. One day last November on a walk in my local park, I saw two women of Chinese descent collecting fallen seeds. I walked over to the tree and took out two plastic zip bags from my back pack. I noticed the women were only collecting the seeds that did not have much or any of the pulp so I did the same. The women were warm; they offered gloves and plastic bags and told me about other seed locations in the park. I did not collect many seeds. I picked up about a dozen or so which I thought would be the right amount for me and my family for a first tasting. I had read that the recommended daily amount to eat was a handful of nuts. When I returned home I stored the seeds in the refrigerator.

A few days later I found a straightforward roast recipe on the Kitchn. I washed the dirt and remaining pulp from the ginkgo seeds then dried them. I heated a tablespoon of olive oil in a skillet to which I added the seeds and salt. I cooked them until the seed coat split then turned off the heat. I transferred the seeds to a plate to cool then removed the nuts. The vibrant green nuts (the true color was not captured in the above photo) were beautiful and looked appetizing. Opinions varied on the flavor. I really liked the nuts. I found them chewy and nutty, and wish I had collected many more to make additional batches. One member of my family refused to try the nuts.

Ginkgo biloba lose their most of their leaves in a single leaf drop in the fall but the nuts can linger on the tree through the winter. There are still trees in fruit in my neighborhood. There have been recent fruit falls, too.

Have you cooked and/or eaten Ginkgo biloba nuts? Please share your experience in the comments.