[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:10.72,0:00:13.62,Default,,0000,0000,0000,,Most of the forest lives in the \Nshadow of the giants
Dialogue: 0,0:00:13.62,0:00:15.76,Default,,0000,0000,0000,,that make up the highest canopy.
Dialogue: 0,0:00:15.76,0:00:17.38,Default,,0000,0000,0000,,These are the oldest trees,
Dialogue: 0,0:00:17.38,0:00:21.00,Default,,0000,0000,0000,,with hundreds of children and \Nthousands of grandchildren.
Dialogue: 0,0:00:21.00,0:00:24.32,Default,,0000,0000,0000,,They check in with their neighbors, \Nsharing food, supplies,
Dialogue: 0,0:00:24.32,0:00:27.47,Default,,0000,0000,0000,,and wisdom gained over their long lives.
Dialogue: 0,0:00:27.47,0:00:33.56,Default,,0000,0000,0000,,They do all this rooted in place, unable \Nto speak, reach out, or move around.
Dialogue: 0,0:00:33.56,0:00:37.13,Default,,0000,0000,0000,,The secret to their success lies \Nunder the forest floor,
Dialogue: 0,0:00:37.13,0:00:41.13,Default,,0000,0000,0000,,where vast root systems support the \Ntowering trunks above.
Dialogue: 0,0:00:41.13,0:00:45.94,Default,,0000,0000,0000,,Partnering with these roots are symbiotic \Nfungi called mycorrhizae.
Dialogue: 0,0:00:45.94,0:00:49.96,Default,,0000,0000,0000,,These fungi have countless branching, \Nthread-like hyphae
Dialogue: 0,0:00:49.96,0:00:52.96,Default,,0000,0000,0000,,that together make up the mycelium.
Dialogue: 0,0:00:52.96,0:00:57.33,Default,,0000,0000,0000,,The mycelium spreads across a much larger \Narea than the tree root system
Dialogue: 0,0:00:57.33,0:01:00.42,Default,,0000,0000,0000,,and connect the roots of different \Ntrees together.
Dialogue: 0,0:01:00.42,0:01:03.52,Default,,0000,0000,0000,,These connections form \Nmycorrhizal networks.
Dialogue: 0,0:01:03.52,0:01:05.16,Default,,0000,0000,0000,,Through mycorrhizal networks,
Dialogue: 0,0:01:05.16,0:01:10.65,Default,,0000,0000,0000,,fungi can pass resources and signaling \Nmolecules between trees.
Dialogue: 0,0:01:10.65,0:01:13.83,Default,,0000,0000,0000,,We know the oldest trees have the \Nlargest mycorrhizal networks
Dialogue: 0,0:01:13.83,0:01:16.06,Default,,0000,0000,0000,,with the most connections to other trees,
Dialogue: 0,0:01:16.06,0:01:19.44,Default,,0000,0000,0000,,but these connections are incredibly \Ncomplicated to trace.
Dialogue: 0,0:01:19.44,0:01:23.78,Default,,0000,0000,0000,,That’s because there are about a hundred \Nspecies of mycorrhizal fungi–
Dialogue: 0,0:01:23.78,0:01:28.48,Default,,0000,0000,0000,,and an individual tree might be colonized \Nby dozens of different fungal organisms,
Dialogue: 0,0:01:28.48,0:01:31.68,Default,,0000,0000,0000,,each of which connects to a \Nunique set of other trees,
Dialogue: 0,0:01:31.68,0:01:36.10,Default,,0000,0000,0000,,which in turn each have their own unique \Nset of fungal associations.
Dialogue: 0,0:01:36.10,0:01:39.29,Default,,0000,0000,0000,,To get a sense of how substances flow \Nthrough this network,
Dialogue: 0,0:01:39.29,0:01:41.14,Default,,0000,0000,0000,,let’s zoom in on sugars,
Dialogue: 0,0:01:41.14,0:01:45.01,Default,,0000,0000,0000,,as they travel from a mature tree to a \Nneighboring seedling.
Dialogue: 0,0:01:45.01,0:01:47.52,Default,,0000,0000,0000,,Sugar’s journey starts high above \Nthe ground,
Dialogue: 0,0:01:47.52,0:01:50.55,Default,,0000,0000,0000,,in the leaves of the tallest trees \Nabove the canopy.
Dialogue: 0,0:01:50.55,0:01:55.43,Default,,0000,0000,0000,,The leaves use the ample sunlight up there\Nto create sugars through photosynthesis.
Dialogue: 0,0:01:55.43,0:01:58.02,Default,,0000,0000,0000,,This essential fuel then travels \Nthrough the tree
Dialogue: 0,0:01:58.02,0:02:00.75,Default,,0000,0000,0000,,to the base of the trunk in the thick sap.
Dialogue: 0,0:02:00.75,0:02:04.07,Default,,0000,0000,0000,,From there, sugar flows down to the roots.
Dialogue: 0,0:02:04.07,0:02:06.72,Default,,0000,0000,0000,,Mycorrhizal fungi encounter the \Ntips of the roots
Dialogue: 0,0:02:06.72,0:02:10.10,Default,,0000,0000,0000,,and either surround or penetrate \Nthe outer root cells,
Dialogue: 0,0:02:10.10,0:02:12.63,Default,,0000,0000,0000,,depending on the type of fungi.
Dialogue: 0,0:02:12.63,0:02:17.47,Default,,0000,0000,0000,,Fungi cannot produce sugars, though they \Nneed them for fuel just like trees do.
Dialogue: 0,0:02:17.47,0:02:18.48,Default,,0000,0000,0000,,They can, however,
Dialogue: 0,0:02:18.48,0:02:22.23,Default,,0000,0000,0000,,collect nutrients from the soil much \Nmore efficiently than tree roots—
Dialogue: 0,0:02:22.23,0:02:25.76,Default,,0000,0000,0000,,and pass these nutrients into \Nthe tree roots.
Dialogue: 0,0:02:25.76,0:02:26.57,Default,,0000,0000,0000,,In general,
Dialogue: 0,0:02:26.57,0:02:30.42,Default,,0000,0000,0000,,substances flow from where they are more \Nabundant to where they are less abundant,
Dialogue: 0,0:02:30.42,0:02:32.32,Default,,0000,0000,0000,,or from source to sink.
Dialogue: 0,0:02:32.32,0:02:36.23,Default,,0000,0000,0000,,That means that the sugars flow from the \Ntree roots into the fungal hyphae.
Dialogue: 0,0:02:36.23,0:02:38.04,Default,,0000,0000,0000,,Once the sugars enter the fungus,
Dialogue: 0,0:02:38.04,0:02:41.33,Default,,0000,0000,0000,,they travel along the hyphae through \Npores between cells
Dialogue: 0,0:02:41.33,0:02:44.41,Default,,0000,0000,0000,,or through special hollow \Ntransporter hyphae.
Dialogue: 0,0:02:44.41,0:02:46.59,Default,,0000,0000,0000,,The fungus absorbs some of the sugars,
Dialogue: 0,0:02:46.59,0:02:50.11,Default,,0000,0000,0000,,but some travels on and enters \Nthe roots of a neighboring tree,
Dialogue: 0,0:02:50.11,0:02:53.40,Default,,0000,0000,0000,,a seedling that grows in the shade and \Nhas less opportunity
Dialogue: 0,0:02:53.40,0:02:56.05,Default,,0000,0000,0000,,to photosynthesize sugars.
Dialogue: 0,0:02:56.05,0:02:59.54,Default,,0000,0000,0000,,But why does fungus transport resources \Nfrom tree to tree?
Dialogue: 0,0:02:59.54,0:03:02.95,Default,,0000,0000,0000,,This is one of the mysteries of the \Nmycorrhizal networks.
Dialogue: 0,0:03:02.95,0:03:07.26,Default,,0000,0000,0000,,It makes sense for fungus to exchange soil\Nnutrients and sugar with a tree—
Dialogue: 0,0:03:07.26,0:03:09.35,Default,,0000,0000,0000,,both parties benefit.
Dialogue: 0,0:03:09.35,0:03:13.35,Default,,0000,0000,0000,,The fungus likely benefits in less obvious\Nways from being part of a network
Dialogue: 0,0:03:13.35,0:03:17.76,Default,,0000,0000,0000,,between trees, but the exact ways \Naren’t totally clear.
Dialogue: 0,0:03:17.76,0:03:20.05,Default,,0000,0000,0000,,Maybe the fungus benefits from \Nhaving connections
Dialogue: 0,0:03:20.05,0:03:22.46,Default,,0000,0000,0000,,with as many different trees as possible,
Dialogue: 0,0:03:22.46,0:03:26.38,Default,,0000,0000,0000,,and maximizes its connections by shuttling\Nmolecules between trees.
Dialogue: 0,0:03:26.38,0:03:29.21,Default,,0000,0000,0000,,Or maybe plants reduce their \Ncontributions to fungi
Dialogue: 0,0:03:29.21,0:03:32.78,Default,,0000,0000,0000,,if the fungi don’t facilitate exchanges \Nbetween trees.
Dialogue: 0,0:03:32.78,0:03:34.13,Default,,0000,0000,0000,,Whatever the reasons,
Dialogue: 0,0:03:34.13,0:03:38.58,Default,,0000,0000,0000,,these fungi pass an incredible amount \Nof information between trees.
Dialogue: 0,0:03:38.58,0:03:42.96,Default,,0000,0000,0000,,Through the mycorrhizae, trees can tell \Nwhen nutrients or signaling molecules
Dialogue: 0,0:03:42.96,0:03:46.30,Default,,0000,0000,0000,,are coming from a member of their \Nown species or not.
Dialogue: 0,0:03:46.30,0:03:49.51,Default,,0000,0000,0000,,They can even tell when information is \Ncoming from a close relative
Dialogue: 0,0:03:49.51,0:03:51.72,Default,,0000,0000,0000,,like a sibling or parent.
Dialogue: 0,0:03:51.72,0:03:54.98,Default,,0000,0000,0000,,Trees can also share information \Nabout events like drought
Dialogue: 0,0:03:54.98,0:03:57.52,Default,,0000,0000,0000,,or insect attacks through their \Nfungal networks,
Dialogue: 0,0:03:57.52,0:04:00.82,Default,,0000,0000,0000,,causing their neighbors to increase \Nproduction of protective enzymes
Dialogue: 0,0:04:00.82,0:04:03.35,Default,,0000,0000,0000,,in anticipation of threats.
Dialogue: 0,0:04:03.35,0:04:08.04,Default,,0000,0000,0000,,The forest’s health relies on these \Nintricate communications and exchanges.
Dialogue: 0,0:04:08.04,0:04:10.70,Default,,0000,0000,0000,,With everything so deeply interconnected,
Dialogue: 0,0:04:10.70,0:04:14.95,Default,,0000,0000,0000,,what impacts one species is bound \Nto impact others.